Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
449
Meeting
International Skeletal Society: Course, September 1991 Elizabeth
Eighteenth
Annual
News
Refresher
Whale&
The 1 8th annual meeting
and refresher course of the InterSkeletal Society (ISS) was held September 25-28, 1 991 , at The Hotel Del Coronado, Coronado (San Diego), California. For more than 500 participants, the meeting sessions included the presentation of annual awards and the Founders Lecture; 64 lectures presented by Society members on special topics of interest; one panel discussion, one minisymposium, and one focus session; quizzes on unknown
Minisymposium
on Bone-Surface
Lesions:
Terminology
national
cases;
and simultaneous
“break-out”
sessions
that allowed
among three reviews of clinical data and research in specific areas of musculoskeletal medicine. The course was designed to cover both current knowledge and attendees
to choose
future directions in the identification of musculoskeletal disorders. The faculty represented an interdisciplinary group of radiologists,
researchers appropriate emphasis
pathologists,
orthopedic
surgeons,
and
Coverage in the AJR is particularly because the program gave special concepts and to new developments including current studies of MR imaging,
Journal
Ste. 103, 2223
discussions
has produced of surface
some
lesions
of
“proliferated
and osteocartilaginous
exostosis
(often
a benign
neoplasm, but much of bone). Of the true
the most important-both the
neoplasms
periosteal include
in frequency
osteosarcoma.
parosteal
mistakenly
osteoma;
consid-
more common than true neoplastic bone-surface and
implica-
Other bone-surface parosteal lipoma; pa-
rosteal
(juxtacortical) chondroma; parosteal hemangioma; subperiosteal osteoid osteoma and osteoblastoma; subperiosteal aneurysmal bone cysts; periosteal or subperiosteal ganglion; parosteal osteosarcoma; periosteal chondrosar-
and sonography.
of Roentgenology,
as they have
lesions,
space limitations preclude a comprehensive descripof the entire meeting; however, the following pages contain summaries of many of the presentations, including the Society awards and Founders Lecture.
editor, American
use of terminology
scientific
in number and name.” Bonesurface lesions can be categorized generally as either pseudoneoplastic (reactive) or neoplastic; the reactive lesions are seen far more often. Subcategories of reactive lesions are juxtacortical myositis ossificans; florid reactive penostitis (Ossifying fasciitis, parosteal fasciitis); turret exostosis (probably an end stage of one of the reactive lesions in the periosteum); bone
tion-is
AJA
Contributing
out that in the
neoplasms
this year, to diagnostic
tion
1
NY) pointed confusion
ered
other
in osteology.
in skeletal radiology, CT, arthrography, bone scanning,
In this minisymposium that was organized and chaired by Peter G. Bullough (New York, NY), Howard Dorfman (Bronx,
coma;
Avenida
and high-grade
do Ia Playa,
Editor’s note.-Meeting
surface
osteosarcoma.
This
list
illus-
La Jolla, CA 92037.
News” articles report the highlights of important national radiology meetings. The intent is to provide Journal readers with succinct, substantive, and accurate reviews of topics of current interest, written in a readable fashion and published promptly after the meeting. The articles will not undergo the peer review usually required of AiR publications, nor will they offer a critique of the information proved. The sole purpose of the series is to apprise AJR readers of topics of current concern in an interesting and timely fashion. 158:449-455,
February
1992 0361-803X/92/i582-0449
© American Roentgen Ray Society
450
trates
MEETING
the importance
of Dr. Dortman’s chaos. Dr. Dortman emphasized
objective,
to create
some order from this terminology In particular,
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
differentiating
from the periosteum
lesions
that
are
the importance
periosteal,
which
are
of
derived
deep layer of the penosteum from the cortex, from those
and separate the that are parosteal, which are derived from the outer (fibrous) layer of the penosteum and grow in an exophytic pattern. Moreover, juxtacortical, often used interchangeably with periosteal and parosteal, simply indicates that the lesion has an extracortical point of origin. Also of note, a paraosseous lesion is one located in soft tissue near a bone; this type of lesion arises outside the bone and the bone’s coverings. Sample images helped illustrate the use of these terms. In one example, a radiograph showed juxtacortical myositis ossificans, which is characterized by its ovoid shape, heavy mineralization more dense in the periphery than in the center of the lesion, central radiolucency, and a soft-tissue cleavage plane between the lesion and the surface or cortex of the bone. Whereas juxtacortical myositis ossificans is a rather common posttraumatic bone-surface lesion, parosteal benign lipoma is far less common, consisting primarily offat but often showing ossification within the fatty tissue and sometimes showing focal areas of cartilaginous differentiation with a cartilage cap. Imaging features of other bone-surface lesions were illustrated, such as subperiosteal benign bone-forming lesions, a rare form of osteoblastoma, frequently seen in the femur, that erodes the cortex of the bone. A much more common lesion, periosteal (juxtacortical) chondroma, develops in the deep layer of the bone; it is a sauceror cupshaped deformity with erosion of the cortex and prominent
solid buttressing of solid reactive bone formation that most often occurs in young adults (third decade of life); it may be difficult to recognize as benign histologically because of its appearance. Also occurring in adults, parosteal osteois a very important bone-surface lesion characterized by a bulky round shape with a radiodense center and an overhanging edge without osteal reaction or buttressing at the borders. Periosteal osteosarcoma may occur in younger patients (second decade of life). A lesion that occurs entirely on the bone’s surface, its usual appearance includes spiculation, poorly defined borders, and tenting. Finally, periosteal (juxtacortical) chondrosarcoma is a bulky lesion that has high cellular
sarcoma
signal
intensity
on T2-weighted
acteristics
is a high degree
periosteal
and
parosteal
some may extend Musculoskeletal
MR
of cellularity lesions
may
into the medullary
images;
one
of its char-
and calcification. invade
the
cortex,
Both and
cavity.
Trauma
Child Abuse The responsibility of radiologists in recognizing ing child abuse was emphasized by M. Joyce CA). Dr. Pais noted that the right of children to from abuse has been recognized only within the although children have always been victims of glect, abandonment, slavery, and murder. In New York City, a child was removed from a
and reportPais (Irvine, be protected past century, violence, nethe 1 870s in very abusive
NEWS
AJA:i58,
February 1992
home by the only legal means possible at that time: reporting the problem to the Society for the Prevention of Cruelty to Animals. Although much progress has been made since then and reported cases have dramatically increased in the past decade (in California, 175,000 cases were reported in 1980 and >500,000 were reported in 1 989), Dr. Pais maintains that physicians still need to do more to recognize and prevent this type of trauma. According to California law (state laws differ), it is the act of abuse rather than the degree of injury that determines whether intervention by medical professionals is appropriate. Dr. Pais discussed several findings that are highly specific for child abuse, and she stressed that the radiologist is obligated to know these signs and to report possible abuse. For example, rib fractures are among the highly specific signs for abuse, especially those occurring either laterally in the posterior ribs or at the costal articulation. Good-quality radiographs are absolutely necessary in these cases; any film that does not penetrate the ribs and spine will certainly not show
these fractures.
(However,
Dr. Pais warned
that the sternal
overlie the ribs and look like rib fractures on radiographs; if the radiologist straightens out the child and takes another image, these “fractures” will disappear.) Multipie fractures have long been considered a sign of abuse; radiologists should note, though, that one large study showed that single fractures were found in 50% of abuse cases. Therefore, the fact that a child has only one fracture does not rule out the possibility of abuse. Other specific signs of possible child abuse include unsuspected lesions, buckethandle fractures, fractures in different stages of healing, metaphyseal fractures, diaphyseal fractures, vertebral body fractures, history that is incompatible with the injury, and sometimes failure to thrive. Dr. Pais noted that the lateral view of the spine is very useful because some fractures cannot be seen on any other view. Other data given by Dr. Pais that might help the physician decide whether to report possible abuse included the following: in abused children, the incidence of fractures varies from 1 1 % to 55%, but (in one series), the largest percentage of fractures (78%) was seen in abused children less than 3 years old and 50% of fractures found in these cases were in children less than 1 year old. Finally, beyond recognizing and reporting suspected child abuse, the radiologist’s role includes documenting data for court (such as the type and location of fracture, a specific indication that the injury is unusual, and the existence of other fractures and their healing stages); careful perusal of the contents of the film jacket; exclusion of other diseases; and the sequestering of films in a legal file so they cannot be obtained and destroyed by the parents. Dr. Pais also stressed the risks of not reporting findings that indicate possible abuse: 40-50% of battered children will be battered again if returned to their home; of these children, 35% will sustain permanent physical damage, 10% will be fatally injured, and 30% will have siblings who also suffer significant injuries. The physician may be embarrassed to confront the parents with a suspicion of abuse, but embarrassment is not sufficient reason to risk the possibility of further injury or even death. segment
may
Stress
MEETING
February 1992
AJR:158,
Ewing
Fractures
Richard
Daffner
(Pittsburgh,
PA)
started
his
talk
with
his
take-home
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
NEWS
message: stress fractures are exceedingly cornmon and are very specific to both location and activity. The two types of stress fractures are fatigue fractures (caused by the effects of a new, strenuous, or frequent activity on normal bone) and insufficiency fractures (caused by the effects of normal activity on abnormal bone). Any force put on a structure affects the structure within its elastic range; once this elastic range is exceeded, fatigue begins and results in fractures ranging from bone microfractures to catastrophic frac-
451
tumor
should
be included
in the differential
diagnosis
because neither has the same imaging characteristics as a stress fracture. If stress fracture is suspected, the physician should not rush into doing a biopsy. Dr. Daffner suggests allowing the “old tincture of time” to work: after 2-4 weeks, a second study should be done to determine the best course of action.
Avulsion
Injuries
fractures are often normal until the stress has continued for some time. However, radionuclide scans, CT scans, and MR
In introducing the topic of avulsion injuries, Helene Pavlov (New York, NY) defined these injuries, according to L. F. Rogers, as “bone failure from tensile force that occurs to the musculoskeletal system, in which bone is the weakest component.” Avulsion injuries are most often seen in adolescent athletes and extremely osteopenic older adults. The athletic injuries occur primarily at the time of closure of the epiphysis and apophyses, or 2.0-2.5 years after closure. Lack of improper warm-up before exercise most often causes avulsion injuries; mechanisms of injury are a single violent contraction of muscle or a repetitive cycle of loading. Most groin pain in adolescents is related to pulls (avulsion injuries) of the large muscular tendons at the insertion sites in the pelvis. The most common site of avulsion injury is the ischial tuberosity, where the hamstrings and abductor musdes originate; this injury results from the attempt to violently
images patient
of edema or change when the pain (i.e., when the bone’s elastic
flex the hip while the knee is extended hurdles).
Even in the symptomatic
Findings in the typical avulsion injury include the crescentshape avulsed bone that is pulled from the origin of the other bone and, during the healing process of the injury, a mottled appearance (areas of radiolucency and increased density). Dr. Pavlov suggests that following Dr. Daffner’s prescription of “a tincture of time” is important with these injuries, also. The injury may look like a tumor, but rather than immediately ordering a biopsy during this active phase, the physician would ask the patient for a history of activities in the past 23 weeks. Indeed, interpretation ofa biopsy specimen obtained during the active phase of avulsion injury is tricky, because these biopsy results may show patterns of abnormal cells that look like tumor to an inexperienced pathologist. MR findings in avulsion injuries of the ischial tuberosity include increased signal within the marrow of the abnormal side compared with the normal side and an increased signal pattern of edema in the surrounding soft tissues.
tures. The mechanisms of stress fracture include direct muscle pull, fatigue, poor posture and stress, and poor posture and abnormal muscle pull. If activity is continued after a stress fracture has begun to develop, the fracture may be completed, the bone fragment may be distracted, or another fracture may occur in the same bone in the opposite limb or in another bone in the same limb. Radiologic findings of stress fracture depend on the stage of the fracture; in general, they include
vague radiolucent ening. Dr. Daffner
cortical
pointed
areas, callus, and endosteal
out that
will show evidence begins to experience
range has been exceeded).
radiologic
findings
thick-
in stress
patient,
radiologic findings may still be normal or include only vague cortical irregularities until the fracture has progressed much further and the patient’s pain has increased significantly. MR imaging and radionuclide imaging can be very useful in the diagnosis of stress fractures of the sacrum. In one study of such fractures, all patients were elderly, osteoporotic women with lower back pain; several had had radiation therapy for pelvic malignancies. Such patients with lower back pain often undergo extensive, unnecessary workups for disk disease or tumor, when actually a diagnosis of stress fracture can be made easily with the appropriate examinations. In this study, radionuclide scans showed unilateral or bilateral areas of tracer activity. When bilateral areas formed the easily recognized “butterfly” or “Honda” sign, CT scans offered confirming evidence of stress fracture. In all these patients, Ti -weighted MR images showed symmetric or asymmetric
areas of low signal within the marrow
area on the sacral side
of the sacroiliac joints; enhanced Ti -weighted
increased; Radiologic the diagnosis.
on T2-weighted images and contrastimages, the intensity of this low signal no associated soft-tissue masses were seen. findings provided no help in making or confirming
The differential myelitis guished
diagnoses
for stress fracture
include osteo-
and osteoid osteoma. Osteomyelitis can be distinby its involvement of both cortices and a radiolucent it generally goes farther through the bone and causes
nidus; more sclerosis
than does stress fracture.
Osteoid
osteomas
involve one cortex, are fusiform, and show a radiolucent nidus that may be quite thick. Neither osteogenic sarcoma nor
Other common superior
sites of avulsion
and anterior
inferior
(e.g., as in jumping
injuries include the anterior
iliac spine,
symphysis
pubis,
and
iliac crest. With injuries to the anterior superior iliac spine, the lesion may not be included on the radiograph of the hip, and so Dr. Pavlov recommends imaging at least one entire half of the pelvis of the involved side in the initial examination of young athletes with groin or hip pain. Avulsion injuries to the symphysis pubis are seen in participants in ice hockey, basketball, and track; two diagnostic patterns are seen: (1) widening of the symphysis pubis, involvement of only one side, sclerotic changes, loss of a smooth cortex, and hypertrophy of the involved side and (2) the same signs plus a visibly avulsed fragment inferiorly at the insertion site of the gracilis
452
MEETING
muscle (the gracilis syndrome). Avulsion injuries of the iliac crest occur when an athlete tries to change direction quickly (e.g., as in figure
skating
or football).
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
found in the lesser trochanter,
Avulsion
injuries
are also
the knee, in which sometimes are avulsed, and the foot, includ-
both the origin and insertion ing the site where the bifurcate ligament originates at the superior anterior spine of the calcaneus, the external digitorum brevis, the peroneus brevis, the plantar aponeurosis, and the sesamoid (where the fracture is typically caused by hyperfiexion, sometimes referred to as “turf toe” because of the effects of playing on artificial turf).
Metabolic
Diseases
and
Anemias
Osteoporosis As a part of a focus session on osteoporosis, Harry K. Genant (San Francisco) presented a discussion of the appropriate applications of bone densitometry in osteoporosisthe “silent epidemic.” He discussed four major applications, the first three of which are well supported by the literature. The first application is assessment of patients with metabolic disorders known to affect the skeleton-disorders that involve secondary osteoporosis (rather than typical senile osteoporosis). Not all patients in this category should be studied with bone densitometry, but this technique should be used in patients in whom the information derived from the study could have specific prognostic and therapeutic implications. Even then, bone densitometry is only part of the clinical evaluation, and the densitometric technique needs to be matched with the clinical issues of the specific disorder (e.g., in Cushing disease, densitometry measurements should be made in a bone such as the spine). The second application of bone densitometry is the assessment of perimenopausal women for whom estrogen replacement therapy (ERT) is being considered. The decision about ERT is based on physician or patient preference, severity of menopausal symptoms, cardiovascular considerations, laboratory evidence of bone loss, and clinical factors. By itself, calcium has not proved to be effective therapy for bone loss
after menopause,
but
a combination
of calcium
and
estrogen
therapy seems to work well; women who have been on EAT for i 5 years show 30-40% more bone density than do control subjects. To determine the need for EAT, the physician should
know that the most specific clinical risk factors for osteoporosis are that the patient is female, Caucasian or Asian, menopausal, elderly, and has a history of atraumatic fracture. The best osteoporosis predictor at menopause is bone density, so bone densitometry appears to be justified as part of the determination of whether EAT is appropriate. Establishing the diagnosis and severity of osteoporosis in
the context
of clinical care is the third common
application
of
bone densitometry. In the diagnosis of osteoporosis, clinical and radiologic findings are important, but bone densitometry results can also help when they are compared with agematched groups and fracture threshold and considered in the context of a continuum of osteopenia with a gradient of risk (i.e., lower bone density indicates higher risk of fracture). Bone densitometry is important in these patients because
NEWS
AJR:158,
February
1992
bone density (bone density
is directly proportional to bone strength in vitro accounts for 70-90% of variance in strength), it correlates highly with fracture severity and prevalence, and it predicts future fracture risk. The consideration of bone
densitometry
results
together
with
radiologic
findings
can
determine appropriate management, ranging from corrective (e.g., calcium and exercise) for a patient with no osteopenia and no fracture to aggressive (e.g., calcitonin, NaFi , bisphosphonates) for a patient with severe osteopenia and fracture. The fourth possible application of bone densitometry is the
most controversial: treatment. Average
serial
assessment
to monitor
disease
bone-density gains after treatment with calcitonin, NaFi , EHDP, or PTH are 2-i 0% (DPA treated) to 4-20% (OCT treated). It has been shown that bone densitometry with 2-point measurement and 2% precision can detect changes above 4% in bone density with 90% confidence (one-tailed test); a 20% change during a relatively short time can be measured easily by bone densitometry. Finally, Dr. Genant mentioned four prerequisites for implementation of wider screening applications of bone densitometry: dissemination of knowledge about osteoporosis management, access of the involved patients to adequate medical care, availability of reliable instruments at a reasonable cost, and uniformity of technical performance.
Gaucher
Disease
Daniel I. Rosenthal (Boston) discussed the clinical, skeletal, and radiologic features of Gaucher disease. Clinical features includes visceral signs (massive organomegaly, especially splenomegaly and less often hepatomegaly) and systemic anemia and thrombocytopenia (leading to increased susceptibility to infections, including osteomyeiitis). Three-quarters of the patients with this disease will have skeletal findings, including pathologic
the
Erlenmeyer
fractures,
flask focal
lytic
deformity, lesions,
diffuse
osteopenia,
osteonecrosis
(50%
of these patients
have hip replacement at some point), osteomyelitis, and bone pain and crisis. The MR features of Gaucher disease are quite striking. The marrow replacement is not random but centrifugal with relative sparing of the epiphysis. The replacement progresses from proximal to distal locations, and this feature allows a i 9 grading system according to involvement shown on MR images: patients with Gaucher disease less than MR grade 5 tend to have no risk of skeletal complications. Imaging methods to diagnose this disease include plain films, dual-energy CT, xenon CT scanning, and MA imaging (including three-dimensional studies). The size of the spleen and amount of bone marrow fat (shown by dual-energy CT and MR imaging) correlate highly with the severity of Gaucher disease. The effects of therapy can also be measured by imaging parameters. After 6 months of IV enzyme replacement therapy, the change in spinal fat content is apparent on either MR images or CT scans. Dr. Rosenthal concluded by saying that radiologists now have the ability to quantify bone marrow in ways not possible in the past; this capability has important implications in the diagnosis and treatment of Gaucher dis-
ease and other diseases.
Paget
MEETING
February 1992
AJR:158,
Disease
George K. Chapman (Hunters Hill, Australia) reviewed current knowledge of Paget disease, which was first described almost
120 years
ago. Although
the medical
community
has
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
not discovered
much more about the nature of this disorder since then, more has been learned about its diagnosis. A wide variety
of imaging
disease’s
techniques
features:
is now
available
to show
the
plain film is the most helpful in diagnosis, and CT may be used for further evaluation;
and bone scanning the disease may be found incidentally imaging does not play a large part
on MR images, in the diagnosis
but MR at this
time. Dr. Chapman
disease, bone
emphasized
which involves
margin
is perhaps
finding
radiologic
the most
this disease:
in diagnosing
important
two
a wide variation
findings
of Paget
of focal disease.
The
important
site to examine margin is an of this disease; a “blade of
A V- or U-shaped
for the diagnosis
grass” margin is often found in younger
patients
(20-40
years
old). Another important phase i (the osteolytic subtle, but bone scans
sign is change in bone density. In phase), bone destruction may be allow early diagnosis by showing
changes
Osteolytic
in bone density.
particularly can cause
evident; difficulties
changes
in flat bones are
Paget disease occurring in diagnosis, but enlarged
one clue, and a clear-cut feature of the disease. enlarged and sclerotic bent cortex.
margin
in long bones bones provide
is once again a diagnostic
Other findings include altered arch, bone, and thickened and sometimes
When Paget disease involves a “bare area” (radiolucent area with no bone), the physician may have difficulty distinguishing the disease from tumor. In one such case, the CT numbers showed the abnormality to have the attenuation of fat, and the patient’s pain was relieved by steroid injections. On the other hand, the physician must stay alert for bare areas where they are not expected; one patient with such findings had a sarcoma with cortical destruction. Prominence of bony structures can also occur in Paget disease, and further imaging examinations may be needed to rule out
sarcoma
and to avoid biopsy.
Rheumatoid
Arthritis,
Psoriatic
Arthritis,
The distinctions rheumatoid
between
arthritis,
teoarthritis
were
Rheumatoid which
psoriatic
presented
the often confused entities of arthritis, and inflammatory osby William Martel (Ann Arbor).
arthritis
causes are characteristic,
juxtacortical bare-area but not specific. These
“wipe
of erosion.
out” the cortex
rather
When rheumatoid
articulating
surfaces,
than show
arthritis it almost
occurs
a discrete
eroero-
ofthe
disease),
and malalignment,
area
in a joint with
always
than one surface. The end stage of rheumatoid characterized by subchondral erosion, osteopenia
arthritis
and
Aeiter
syndrome.
Also,
occasionally
bone apposition
may obscure
bone erosion.
In psoriatic
ar-
thritis, the erosions occur in bare areas, and when these are associated with fuzzy bone apposition at the bases of the distal phalanges in the hands, they cause the “mouse ears” appearance. Erosions may be present without osteopenia, but in advanced disease, osteopenia is frequently present. In approximately 25% of patients with psoriatic arthritis, the “single-ray” pattern is seen (in which joints of one ray are selectively affected); also in 20-25% of patients, a polyarticular unilateral pattern appears that is virtually pathognomonic for psoriatic arthritis (as opposed to rheumatoid arthritis). A commonly affected joint in the foot is the interphalangeal joint of the great toe. Posterior calyceal spurs are often irregular
and indistinct
in outline
as contrasted
to spaces
with sharp
margins that may be seen in rheumatoid arthritis. Osteoarthritis usually affects both proximal and terminal joints; in erosive osteoarthritis, the striking inflammation may last for months and my be confusing to clinicians. However, some features that can help distinguish osteoarthritis include sparing of metacarpophalangeal joints and the pattern of subchondral rather than juxtachondral bone erosion. Also, in osteoarthritis, bone apposition is not common; when it does occur, it is linear and minimal and always associated with severe destruction of adjacent joints. It is never associated with fuzzy bone apposition, as is often seen in psoriatic arthritis.
of Osteoarthritis Forrester
(Los
Angeles) discussed the radiology the investigation of the underlying of cartilage. She first urged that physicians eliminate the concept that overuse of a joint can cause osteoarthritis; no evidence (e.g., studies on the hands of players of string instruments and on the feet of longdistance runners) indicates that placing great stress on a joint results in a higher incidence of this disease, and “even doctors who hate running” have been unable to prove that running causes osteoarthritis. Whereas rheumatoid arthritis is a synovial disease, osteoarthritis is a disease of the cartilage. Aadiologic findings of osteoarthritis include nonuniform cartilage loss and segmental cartilage narrowing; secondary to this denuded area, bone
of osteoarthritis, including cause for the destruction
sions occur in other articular diseases (but not in osteoarthritis). Erosion usually occurs earlier in the metacarpal areas than in the articulating phalanges. The erosive process may
multiple
in psoriatic
almost never occurs in osteoarthritis). occur in rheumatoid arthritis, but are rare
in rheumatoid arthritis, erosions develop in the feet before they develop in the hands; however, it is atypical for severe erosions to be present in the foot in the absence of any erosions in the hand. Periosteal bone apposition is typically absent in rheumatoid arthritis, but may be minimal (possibly at sites of tenosynovitis). Often confused with rheumatoid arthritis because arthritis may precede skin lesions, psoriatic arthritis differs from rheumatoid arthritis in its tendency to involve the terminal interphalangeal joints and produce bone apposition. Concomitant
Deborah
and Inflammatory
Osteoarthritis
simply
(volar subluxation Pseudocysts may
The Radiology
Arthritis
sions,
453
NEWS
affects more arthritis is
(a hallmark
often with volar subluxation
formations cysts. thritis,
result
in subchondral
sclerosis
and subchondral
When these features indicate the diagnosis of osteoarthe radiologist should then consider the causes of the
454
MEETING
disease and determine whether or secondary. Unfortunately, making these
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
difficult
or impossible.
Dr.
the osteoarthritis
is primary
determinations
is sometimes
described
a patient
with
may
not
reveal
the
cause.
In
one series, no clue was provided about the cause of degeneration but the classic progression of osteoarthritis was illustrated nicely: initial typical radiographic findings of superior segmental narrowing and subchondral cysts, followed 2 years later by not much change except for some change in the cysts, and then end-stage disease with huge osteophytes seen 4 years after the original radiograph. Given these difficulties, radiologists should look for specific evidence of secondary osteoarthritis: trauma, alteration of the articular surfaces so that they become incongruent (which leads to uneven wear and tear), and deposition of something in the cartilage to initiate the destruction with fissuring. In the case of a gunshot victim, one bullet caused osteoarthritis in
ways:
by avascular
necrosis
from the damage
actually done by the bullet and by lead arthropathy (which always leads to secondary degenerative disease). Abnormalities of articular surfaces seen in secondary osteoarthritis most commonly result from an untreated, congenital dislocated hip; a less common cause is avascular necrosis; and a very rate cause is spondyloepiphyseal dysplasia. Calcification in the cartilage provides a hint that cartilage deposition of crystals of pigmentation has occurred; the “Milwaukee shoulder” is a complication of hydroxyapatite deposition disease. Also, overgrowth of cartilage, rather than deposition in it, may cause joint degeneration. Neuropathic joints can look like osteoarthritis with absence of osteoporosis and presence of narrowing with little proliferative change. To distinguish between these two entities, the radiologist should check for the huge chronic effusions characteristic of neuropathic arthropathy. If these effusions can be tapped, they are noninflammatory, and this is diagnostic of neuropathy-a diagnosis that becomes even more evident as the neuropathic joints crumble, possibly within
weeks. MR Imaging
Adult
and
Skeletal
February
1992
limitations
end-stage hip disease, in whom the radiograph showed multiple metallic densities around the hip joint that represented acupuncture needles left in attempts to resolve hip pain over many years. One could not tell from this one film the cause of the disease; it may have resulted from infection, avascular necrosis, or treatment with remedies that contained prednisone. One expert (Hams) has hypothesized for years that end-stage hip disease without obvious cause is usually the result of unrecognized disease in childhood.
two distinct
AJR:i58,
in depicting fine details of structures with tightly hydrogen, such as bone, its inability to be used in patients who have pacemakers, and its high cost. MA imaging is an ideal tool for studying the anatomy of the hip: individual muscles and tendons can be identified better than with any other method. The use of multiplanar imaging enhances the depiction of many structures, especially tendons. MR findings in adult hip disease should be correlated with clinical and pathologic results to optimize diagnostic accuracy. Although MA results are highly sensitive for detecting abnormalities within high signal intensity marrow, the low signal intensity of the abnormalities is often nonspecific (trauma, tumor, and infection may all look similar). Also, the low signal intensity of active hematopoietic bone marrow may be mistaken to be abnormal. MA imaging can be used preoperatively to show marrow and soft-tissue extent of tumors; MA images can also identify skip lesions in the marrow and invasion of the hip joint. MA has a high sensitivity for detection of metastases, and can be used as an adjunct to radionuclide scanning and radiography in equivocal cases. For trauma to the adult hip, CT is more effective in depicting acetabular fractures and intraarticular fragments. However, MA images may show the viability of the bone marrow of the femoral head after its fracture and may be useful in showing injuries to ligaments and tendons. Also, MA imaging is capable of showing small fluid collections within and around the hip. In concluding, Dr. Bassett noted that, despite the advantages of MR imaging, it should be used routinely in adult hip disease but should be reserved for cases in which it can provide clinically useful information that is not available with less expensive methods.
bound
Forrester
Even a series of radiographs
NEWS
Diseases
Hip Diseases
In his discussion, Lawrence W. Bassett (Los Angeles) first listed the advantages of MA imaging in adult hip disease: the high sensitivity of MA in detection of bone marrow lesions (due to the high signal intensity of normal bone marrow); the inherently high contrast, resulting in exquisite depiction of soft-tissue structures, and the capability for direct imaging in any plane. The disadvantages of MA imaging include its
Detection
of Occult
Injuries
In her presentation, Dr. Frieda Feldman (New York, NY) focused on the use of MA imaging in cases of acute, severe, persistent lower back pain (especially in older patients). Her first example was that of a 60-year-old woman (5 years after a mastectomy) who arrived with several studies, including a hard-to-evaluate
pelvic
study
that
was
perhaps
suggestive
of
sclerosis; this study led to CT scanning, which in turn led to biopsy, interpretations of which ranged from diagnoses of metastases and primary tumor to nondiagnosis (“insufficient tissue”). Actually, the cause of this patient’s pain was an insufficiency stress fracture, and it was clearly identified by MR imaging. In another of many similar cases, a 50-year-old woman with lower back pain “came in with stacks of films and CTs done by the unwary” and a biopsy diagnosis of metastases; the MA image definitively showed the sacral fracture that was causing the pain. Dr. Feldman emphasized the importance of using MR imaging to ensure that stress fractures are not misdiagnosed as tumor and that identification of a possible insufficiency stress fracture can be aided by looking for associated fractures in typical locations, including the spine, pubic pelvis, and supraacetabular region. A traumatic hip fracture in a 70-year-old woman was missed on “initial, cost-conscious” tomograms. Coronal and axial MR images definitively identified the fracture and provided the
diagnosis.
Follow-up
corroborate
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
MEETING
February 1992
AJR:158,
tomograms
the fracture.
(2-mm
The weakened
cuts)
still
femoral
failed
to
neck was
pinned on the strength of the MA findings. In the section of her talk that she called “the really esoteric, and occult: the skeletal symptom in search of a cause,” Dr. Feldman discussed those patients with vague plain films. She gave several cases in which tomograms were unable to provide diagnosis for symptomatic patients, so that MR im-
aging was requested as somewhat of a last resort. In one emergent case, a 50-year-old man with a painful knee effusion had inconclusive radiographic and tomographic studies; when MR imaging was done, the results revealed a “multitude of soft-tissue sins,” including the known effusion, a medial meniscal tear, abnormal signal in the posterior tibial plateau mdicating a fracture, along with an abnormal lateral ligament, increased buckling of the posterior cruciate ligament, absence of a definite anterior cruciate ligament, and a lateral meniscal
tear.
Based
concluded
Awards
on this and other
that MR imaging
experiences,
is a “heaven-sent
of the International
Skeletal
Dr. Feldman problem
solver.”
Society
Two awards are given at each annual meeting of this society: The highest award is the Founders Medal and the second
highest
The 155 Founders
is the Founders
Gold Medal
Walter BossIer (Winterthur, presented
the
Lecture.
Founders
Switzerland),
Medal
to John
the ISS president, A. Kirkpatrick, Jr.,
(Boston) a charter member of the ISS and its fourth president, whom Dr. Bessler described as a “perfect gentleman from top to toe.” Dr. Kirkpatrick was awarded this honor not only for his contributions to the 155 in particular and to the body of knowledge concerning skeletal radiology in general but
also for his publications (1 07 journal articles, 27 book chapters, and the book Orthopedic Diseases); his editorial services to many medical publications; his active memberships in other professional societies (including the John Caffey Society for Pediatric Radiology, the Fleischner Society, the American Roentgen Ray Society [past president, ARRS], The Society for Pediatric Radiology [past president, SPA], and honorary
memberships in 22 other societies); and his receipt Gold Medals of both the ARAS and the SPA.
of the
NEWS
455
Dr. Pitt began his Founders Lecture, “Rickets and Osteomalacia,” with a history of rickets, which he called our first
real “environmental monplace prevalence
is reflected
disease”
by a i 900 study
Lecture
For the second highest award, Michael J. Pitt (Tucson) gave the Founders Lecture in honor of Jack Edeiken (Houston), one of the three founders of the ISS.
Dr. Pitt’s introduction accomplishments
to his lecture focused
of Dr. Edeiken,
ing teacher, accomplished scholar nosis of Diseases of the Bones], friend.”
Besides
being
a founder
“superior
[author
on the life and
clinician,
outstand-
of Roentgen
founder of the ISS, of the ISS, Dr. Edeiken
Diag-
and has
held many other important posts in the organization, including secretary-treasurer and president. Dr. Pitt summarized Dr. Edeiken’s contribution to ISS by saying, “Without him, ISS would not be what it is today.”
it first became
corn-
the Industrial Revolution. Its in the early part of this century
that found
that 80% of infants
less than 2 years old in Boston had rickets. Vitamin Ddeficiency rickets virtually disappeared in the early 1 920s with the discovery and synthesis of vitamin D. Rickets refractory
to vitamin
D comprise
the cases seen by physicians
today.
(We now know that “vitamin D” is not a vitamin at all, but a prohormone formed naturally in the body that paradoxically both breaks down bone and creates new bone.) The terms rickets and osteomalacia represent a group of diseases with similar gross, radiologic, and histologic abnormalities; more than 50 reported diseases have changes characteristic of rickets and osteomalacia. Originally, these two diseases were considered separate entities, rickets occurring in the skeletally immature, and osteomalacia occurring in the cortical and spongy bone; they are, however, aspects of the same disease, and the physician needs to realize that rickets
and osteomalacia immature patients. systemic
coexist
diseases.
rickets
in the long
bones
of skeletally
Also, both rickets and osteomalacia Dr. Pitt also discussed the diagnosis
and osteomalacia.
In rickets,
the increase
are of
in the num-
ber of cells in the physeal zone of hypertrophy is haphazard (both in axial and latitudinal directions); also, there are fewer than normal cartilaginous bars laid down, and they cannot be mineralized. These characteristics contrast dramatically with the orderly columns in the normally developing growth plate. The radiologic diagnosis of rickets includes increased longitudinal and latitudinal radiolucency in the growth plate, decreased mineralization in the zones of primary and secondary spongiosa, and disorganization. In osteomalacia, the amount of bone is less than in the cortex of the normal medullary cavity, the canals are widened, and a pink-staining substance (osteoid seams) borders the canals. Radiologically, osteomalacia is characterized by osteopenia, decreased bone in cortex, Looser zones, osteoid accumulation, bending, and secondary hyperthyroidism. Finally, Dr. Pitt discussed the approach that the radiologist can take to discover the cause of diagnosed rickets or osteomalacia. Although many of the findings are nonspecific for any one disease in this group of diseases, he recommended a systematic consideration of the three main types of causes
for the diagnostician The ISS Founders
because
in England during in the United States
to consider:
difficulties,
including
or kidney
problems;
usually
phosphate
hypophosphatemia,
or tumor-associated with either tumors
(i)
gastrointestinal
(2) phosphate (a renal tubular uremic
D metabolism
vitamin
malabsorption
or calcium disorder,
osteopathy,
disorder, including or tumor treatment);
and liver
disorders-
such as X-linked Fanconi
disorders
syndrome,
associated
and (3) other (a small
of patients whose radiologic findings look like but who do not have biochemical features of rickets),
percentage
rickets including
cases
of metaphyseal
chondroplasia,
axial osteo-
malacia, and hyperphosphatasemia. Some characteristics seen in these categories are more specific than others, but using such systematic classification may help make the physician more comfortable with diagnosing and treating patients with the end-stage diseases of rickets and osteomalacia.
449
Meeting
International Skeletal Society: Course, September 1991 Elizabeth
Eighteenth
Annual
News
Refresher
Whale&
The 1 8th annual meeting
and refresher course of the InterSkeletal Society (ISS) was held September 25-28, 1 991 , at The Hotel Del Coronado, Coronado (San Diego), California. For more than 500 participants, the meeting sessions included the presentation of annual awards and the Founders Lecture; 64 lectures presented by Society members on special topics of interest; one panel discussion, one minisymposium, and one focus session; quizzes on unknown
Minisymposium
on Bone-Surface
Lesions:
Terminology
national
cases;
and simultaneous
“break-out”
sessions
that allowed
among three reviews of clinical data and research in specific areas of musculoskeletal medicine. The course was designed to cover both current knowledge and attendees
to choose
future directions in the identification of musculoskeletal disorders. The faculty represented an interdisciplinary group of radiologists,
researchers appropriate emphasis
pathologists,
orthopedic
surgeons,
and
Coverage in the AJR is particularly because the program gave special concepts and to new developments including current studies of MR imaging,
Journal
Ste. 103, 2223
discussions
has produced of surface
some
lesions
of
“proliferated
and osteocartilaginous
exostosis
(often
a benign
neoplasm, but much of bone). Of the true
the most important-both the
neoplasms
periosteal include
in frequency
osteosarcoma.
parosteal
mistakenly
osteoma;
consid-
more common than true neoplastic bone-surface and
implica-
Other bone-surface parosteal lipoma; pa-
rosteal
(juxtacortical) chondroma; parosteal hemangioma; subperiosteal osteoid osteoma and osteoblastoma; subperiosteal aneurysmal bone cysts; periosteal or subperiosteal ganglion; parosteal osteosarcoma; periosteal chondrosar-
and sonography.
of Roentgenology,
as they have
lesions,
space limitations preclude a comprehensive descripof the entire meeting; however, the following pages contain summaries of many of the presentations, including the Society awards and Founders Lecture.
editor, American
use of terminology
scientific
in number and name.” Bonesurface lesions can be categorized generally as either pseudoneoplastic (reactive) or neoplastic; the reactive lesions are seen far more often. Subcategories of reactive lesions are juxtacortical myositis ossificans; florid reactive penostitis (Ossifying fasciitis, parosteal fasciitis); turret exostosis (probably an end stage of one of the reactive lesions in the periosteum); bone
tion-is
AJA
Contributing
out that in the
neoplasms
this year, to diagnostic
tion
1
NY) pointed confusion
ered
other
in osteology.
in skeletal radiology, CT, arthrography, bone scanning,
In this minisymposium that was organized and chaired by Peter G. Bullough (New York, NY), Howard Dorfman (Bronx,
coma;
Avenida
and high-grade
do Ia Playa,
Editor’s note.-Meeting
surface
osteosarcoma.
This
list
illus-
La Jolla, CA 92037.
News” articles report the highlights of important national radiology meetings. The intent is to provide Journal readers with succinct, substantive, and accurate reviews of topics of current interest, written in a readable fashion and published promptly after the meeting. The articles will not undergo the peer review usually required of AiR publications, nor will they offer a critique of the information proved. The sole purpose of the series is to apprise AJR readers of topics of current concern in an interesting and timely fashion. 158:449-455,
February
1992 0361-803X/92/i582-0449
© American Roentgen Ray Society
450
trates
MEETING
the importance
of Dr. Dortman’s chaos. Dr. Dortman emphasized
objective,
to create
some order from this terminology In particular,
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
differentiating
from the periosteum
lesions
that
are
the importance
periosteal,
which
are
of
derived
deep layer of the penosteum from the cortex, from those
and separate the that are parosteal, which are derived from the outer (fibrous) layer of the penosteum and grow in an exophytic pattern. Moreover, juxtacortical, often used interchangeably with periosteal and parosteal, simply indicates that the lesion has an extracortical point of origin. Also of note, a paraosseous lesion is one located in soft tissue near a bone; this type of lesion arises outside the bone and the bone’s coverings. Sample images helped illustrate the use of these terms. In one example, a radiograph showed juxtacortical myositis ossificans, which is characterized by its ovoid shape, heavy mineralization more dense in the periphery than in the center of the lesion, central radiolucency, and a soft-tissue cleavage plane between the lesion and the surface or cortex of the bone. Whereas juxtacortical myositis ossificans is a rather common posttraumatic bone-surface lesion, parosteal benign lipoma is far less common, consisting primarily offat but often showing ossification within the fatty tissue and sometimes showing focal areas of cartilaginous differentiation with a cartilage cap. Imaging features of other bone-surface lesions were illustrated, such as subperiosteal benign bone-forming lesions, a rare form of osteoblastoma, frequently seen in the femur, that erodes the cortex of the bone. A much more common lesion, periosteal (juxtacortical) chondroma, develops in the deep layer of the bone; it is a sauceror cupshaped deformity with erosion of the cortex and prominent
solid buttressing of solid reactive bone formation that most often occurs in young adults (third decade of life); it may be difficult to recognize as benign histologically because of its appearance. Also occurring in adults, parosteal osteois a very important bone-surface lesion characterized by a bulky round shape with a radiodense center and an overhanging edge without osteal reaction or buttressing at the borders. Periosteal osteosarcoma may occur in younger patients (second decade of life). A lesion that occurs entirely on the bone’s surface, its usual appearance includes spiculation, poorly defined borders, and tenting. Finally, periosteal (juxtacortical) chondrosarcoma is a bulky lesion that has high cellular
sarcoma
signal
intensity
on T2-weighted
acteristics
is a high degree
periosteal
and
parosteal
some may extend Musculoskeletal
MR
of cellularity lesions
may
into the medullary
images;
one
of its char-
and calcification. invade
the
cortex,
Both and
cavity.
Trauma
Child Abuse The responsibility of radiologists in recognizing ing child abuse was emphasized by M. Joyce CA). Dr. Pais noted that the right of children to from abuse has been recognized only within the although children have always been victims of glect, abandonment, slavery, and murder. In New York City, a child was removed from a
and reportPais (Irvine, be protected past century, violence, nethe 1 870s in very abusive
NEWS
AJA:i58,
February 1992
home by the only legal means possible at that time: reporting the problem to the Society for the Prevention of Cruelty to Animals. Although much progress has been made since then and reported cases have dramatically increased in the past decade (in California, 175,000 cases were reported in 1980 and >500,000 were reported in 1 989), Dr. Pais maintains that physicians still need to do more to recognize and prevent this type of trauma. According to California law (state laws differ), it is the act of abuse rather than the degree of injury that determines whether intervention by medical professionals is appropriate. Dr. Pais discussed several findings that are highly specific for child abuse, and she stressed that the radiologist is obligated to know these signs and to report possible abuse. For example, rib fractures are among the highly specific signs for abuse, especially those occurring either laterally in the posterior ribs or at the costal articulation. Good-quality radiographs are absolutely necessary in these cases; any film that does not penetrate the ribs and spine will certainly not show
these fractures.
(However,
Dr. Pais warned
that the sternal
overlie the ribs and look like rib fractures on radiographs; if the radiologist straightens out the child and takes another image, these “fractures” will disappear.) Multipie fractures have long been considered a sign of abuse; radiologists should note, though, that one large study showed that single fractures were found in 50% of abuse cases. Therefore, the fact that a child has only one fracture does not rule out the possibility of abuse. Other specific signs of possible child abuse include unsuspected lesions, buckethandle fractures, fractures in different stages of healing, metaphyseal fractures, diaphyseal fractures, vertebral body fractures, history that is incompatible with the injury, and sometimes failure to thrive. Dr. Pais noted that the lateral view of the spine is very useful because some fractures cannot be seen on any other view. Other data given by Dr. Pais that might help the physician decide whether to report possible abuse included the following: in abused children, the incidence of fractures varies from 1 1 % to 55%, but (in one series), the largest percentage of fractures (78%) was seen in abused children less than 3 years old and 50% of fractures found in these cases were in children less than 1 year old. Finally, beyond recognizing and reporting suspected child abuse, the radiologist’s role includes documenting data for court (such as the type and location of fracture, a specific indication that the injury is unusual, and the existence of other fractures and their healing stages); careful perusal of the contents of the film jacket; exclusion of other diseases; and the sequestering of films in a legal file so they cannot be obtained and destroyed by the parents. Dr. Pais also stressed the risks of not reporting findings that indicate possible abuse: 40-50% of battered children will be battered again if returned to their home; of these children, 35% will sustain permanent physical damage, 10% will be fatally injured, and 30% will have siblings who also suffer significant injuries. The physician may be embarrassed to confront the parents with a suspicion of abuse, but embarrassment is not sufficient reason to risk the possibility of further injury or even death. segment
may
Stress
MEETING
February 1992
AJR:158,
Ewing
Fractures
Richard
Daffner
(Pittsburgh,
PA)
started
his
talk
with
his
take-home
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
NEWS
message: stress fractures are exceedingly cornmon and are very specific to both location and activity. The two types of stress fractures are fatigue fractures (caused by the effects of a new, strenuous, or frequent activity on normal bone) and insufficiency fractures (caused by the effects of normal activity on abnormal bone). Any force put on a structure affects the structure within its elastic range; once this elastic range is exceeded, fatigue begins and results in fractures ranging from bone microfractures to catastrophic frac-
451
tumor
should
be included
in the differential
diagnosis
because neither has the same imaging characteristics as a stress fracture. If stress fracture is suspected, the physician should not rush into doing a biopsy. Dr. Daffner suggests allowing the “old tincture of time” to work: after 2-4 weeks, a second study should be done to determine the best course of action.
Avulsion
Injuries
fractures are often normal until the stress has continued for some time. However, radionuclide scans, CT scans, and MR
In introducing the topic of avulsion injuries, Helene Pavlov (New York, NY) defined these injuries, according to L. F. Rogers, as “bone failure from tensile force that occurs to the musculoskeletal system, in which bone is the weakest component.” Avulsion injuries are most often seen in adolescent athletes and extremely osteopenic older adults. The athletic injuries occur primarily at the time of closure of the epiphysis and apophyses, or 2.0-2.5 years after closure. Lack of improper warm-up before exercise most often causes avulsion injuries; mechanisms of injury are a single violent contraction of muscle or a repetitive cycle of loading. Most groin pain in adolescents is related to pulls (avulsion injuries) of the large muscular tendons at the insertion sites in the pelvis. The most common site of avulsion injury is the ischial tuberosity, where the hamstrings and abductor musdes originate; this injury results from the attempt to violently
images patient
of edema or change when the pain (i.e., when the bone’s elastic
flex the hip while the knee is extended hurdles).
Even in the symptomatic
Findings in the typical avulsion injury include the crescentshape avulsed bone that is pulled from the origin of the other bone and, during the healing process of the injury, a mottled appearance (areas of radiolucency and increased density). Dr. Pavlov suggests that following Dr. Daffner’s prescription of “a tincture of time” is important with these injuries, also. The injury may look like a tumor, but rather than immediately ordering a biopsy during this active phase, the physician would ask the patient for a history of activities in the past 23 weeks. Indeed, interpretation ofa biopsy specimen obtained during the active phase of avulsion injury is tricky, because these biopsy results may show patterns of abnormal cells that look like tumor to an inexperienced pathologist. MR findings in avulsion injuries of the ischial tuberosity include increased signal within the marrow of the abnormal side compared with the normal side and an increased signal pattern of edema in the surrounding soft tissues.
tures. The mechanisms of stress fracture include direct muscle pull, fatigue, poor posture and stress, and poor posture and abnormal muscle pull. If activity is continued after a stress fracture has begun to develop, the fracture may be completed, the bone fragment may be distracted, or another fracture may occur in the same bone in the opposite limb or in another bone in the same limb. Radiologic findings of stress fracture depend on the stage of the fracture; in general, they include
vague radiolucent ening. Dr. Daffner
cortical
pointed
areas, callus, and endosteal
out that
will show evidence begins to experience
range has been exceeded).
radiologic
findings
thick-
in stress
patient,
radiologic findings may still be normal or include only vague cortical irregularities until the fracture has progressed much further and the patient’s pain has increased significantly. MR imaging and radionuclide imaging can be very useful in the diagnosis of stress fractures of the sacrum. In one study of such fractures, all patients were elderly, osteoporotic women with lower back pain; several had had radiation therapy for pelvic malignancies. Such patients with lower back pain often undergo extensive, unnecessary workups for disk disease or tumor, when actually a diagnosis of stress fracture can be made easily with the appropriate examinations. In this study, radionuclide scans showed unilateral or bilateral areas of tracer activity. When bilateral areas formed the easily recognized “butterfly” or “Honda” sign, CT scans offered confirming evidence of stress fracture. In all these patients, Ti -weighted MR images showed symmetric or asymmetric
areas of low signal within the marrow
area on the sacral side
of the sacroiliac joints; enhanced Ti -weighted
increased; Radiologic the diagnosis.
on T2-weighted images and contrastimages, the intensity of this low signal no associated soft-tissue masses were seen. findings provided no help in making or confirming
The differential myelitis guished
diagnoses
for stress fracture
include osteo-
and osteoid osteoma. Osteomyelitis can be distinby its involvement of both cortices and a radiolucent it generally goes farther through the bone and causes
nidus; more sclerosis
than does stress fracture.
Osteoid
osteomas
involve one cortex, are fusiform, and show a radiolucent nidus that may be quite thick. Neither osteogenic sarcoma nor
Other common superior
sites of avulsion
and anterior
inferior
(e.g., as in jumping
injuries include the anterior
iliac spine,
symphysis
pubis,
and
iliac crest. With injuries to the anterior superior iliac spine, the lesion may not be included on the radiograph of the hip, and so Dr. Pavlov recommends imaging at least one entire half of the pelvis of the involved side in the initial examination of young athletes with groin or hip pain. Avulsion injuries to the symphysis pubis are seen in participants in ice hockey, basketball, and track; two diagnostic patterns are seen: (1) widening of the symphysis pubis, involvement of only one side, sclerotic changes, loss of a smooth cortex, and hypertrophy of the involved side and (2) the same signs plus a visibly avulsed fragment inferiorly at the insertion site of the gracilis
452
MEETING
muscle (the gracilis syndrome). Avulsion injuries of the iliac crest occur when an athlete tries to change direction quickly (e.g., as in figure
skating
or football).
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
found in the lesser trochanter,
Avulsion
injuries
are also
the knee, in which sometimes are avulsed, and the foot, includ-
both the origin and insertion ing the site where the bifurcate ligament originates at the superior anterior spine of the calcaneus, the external digitorum brevis, the peroneus brevis, the plantar aponeurosis, and the sesamoid (where the fracture is typically caused by hyperfiexion, sometimes referred to as “turf toe” because of the effects of playing on artificial turf).
Metabolic
Diseases
and
Anemias
Osteoporosis As a part of a focus session on osteoporosis, Harry K. Genant (San Francisco) presented a discussion of the appropriate applications of bone densitometry in osteoporosisthe “silent epidemic.” He discussed four major applications, the first three of which are well supported by the literature. The first application is assessment of patients with metabolic disorders known to affect the skeleton-disorders that involve secondary osteoporosis (rather than typical senile osteoporosis). Not all patients in this category should be studied with bone densitometry, but this technique should be used in patients in whom the information derived from the study could have specific prognostic and therapeutic implications. Even then, bone densitometry is only part of the clinical evaluation, and the densitometric technique needs to be matched with the clinical issues of the specific disorder (e.g., in Cushing disease, densitometry measurements should be made in a bone such as the spine). The second application of bone densitometry is the assessment of perimenopausal women for whom estrogen replacement therapy (ERT) is being considered. The decision about ERT is based on physician or patient preference, severity of menopausal symptoms, cardiovascular considerations, laboratory evidence of bone loss, and clinical factors. By itself, calcium has not proved to be effective therapy for bone loss
after menopause,
but
a combination
of calcium
and
estrogen
therapy seems to work well; women who have been on EAT for i 5 years show 30-40% more bone density than do control subjects. To determine the need for EAT, the physician should
know that the most specific clinical risk factors for osteoporosis are that the patient is female, Caucasian or Asian, menopausal, elderly, and has a history of atraumatic fracture. The best osteoporosis predictor at menopause is bone density, so bone densitometry appears to be justified as part of the determination of whether EAT is appropriate. Establishing the diagnosis and severity of osteoporosis in
the context
of clinical care is the third common
application
of
bone densitometry. In the diagnosis of osteoporosis, clinical and radiologic findings are important, but bone densitometry results can also help when they are compared with agematched groups and fracture threshold and considered in the context of a continuum of osteopenia with a gradient of risk (i.e., lower bone density indicates higher risk of fracture). Bone densitometry is important in these patients because
NEWS
AJR:158,
February
1992
bone density (bone density
is directly proportional to bone strength in vitro accounts for 70-90% of variance in strength), it correlates highly with fracture severity and prevalence, and it predicts future fracture risk. The consideration of bone
densitometry
results
together
with
radiologic
findings
can
determine appropriate management, ranging from corrective (e.g., calcium and exercise) for a patient with no osteopenia and no fracture to aggressive (e.g., calcitonin, NaFi , bisphosphonates) for a patient with severe osteopenia and fracture. The fourth possible application of bone densitometry is the
most controversial: treatment. Average
serial
assessment
to monitor
disease
bone-density gains after treatment with calcitonin, NaFi , EHDP, or PTH are 2-i 0% (DPA treated) to 4-20% (OCT treated). It has been shown that bone densitometry with 2-point measurement and 2% precision can detect changes above 4% in bone density with 90% confidence (one-tailed test); a 20% change during a relatively short time can be measured easily by bone densitometry. Finally, Dr. Genant mentioned four prerequisites for implementation of wider screening applications of bone densitometry: dissemination of knowledge about osteoporosis management, access of the involved patients to adequate medical care, availability of reliable instruments at a reasonable cost, and uniformity of technical performance.
Gaucher
Disease
Daniel I. Rosenthal (Boston) discussed the clinical, skeletal, and radiologic features of Gaucher disease. Clinical features includes visceral signs (massive organomegaly, especially splenomegaly and less often hepatomegaly) and systemic anemia and thrombocytopenia (leading to increased susceptibility to infections, including osteomyeiitis). Three-quarters of the patients with this disease will have skeletal findings, including pathologic
the
Erlenmeyer
fractures,
flask focal
lytic
deformity, lesions,
diffuse
osteopenia,
osteonecrosis
(50%
of these patients
have hip replacement at some point), osteomyelitis, and bone pain and crisis. The MR features of Gaucher disease are quite striking. The marrow replacement is not random but centrifugal with relative sparing of the epiphysis. The replacement progresses from proximal to distal locations, and this feature allows a i 9 grading system according to involvement shown on MR images: patients with Gaucher disease less than MR grade 5 tend to have no risk of skeletal complications. Imaging methods to diagnose this disease include plain films, dual-energy CT, xenon CT scanning, and MA imaging (including three-dimensional studies). The size of the spleen and amount of bone marrow fat (shown by dual-energy CT and MR imaging) correlate highly with the severity of Gaucher disease. The effects of therapy can also be measured by imaging parameters. After 6 months of IV enzyme replacement therapy, the change in spinal fat content is apparent on either MR images or CT scans. Dr. Rosenthal concluded by saying that radiologists now have the ability to quantify bone marrow in ways not possible in the past; this capability has important implications in the diagnosis and treatment of Gaucher dis-
ease and other diseases.
Paget
MEETING
February 1992
AJR:158,
Disease
George K. Chapman (Hunters Hill, Australia) reviewed current knowledge of Paget disease, which was first described almost
120 years
ago. Although
the medical
community
has
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
not discovered
much more about the nature of this disorder since then, more has been learned about its diagnosis. A wide variety
of imaging
disease’s
techniques
features:
is now
available
to show
the
plain film is the most helpful in diagnosis, and CT may be used for further evaluation;
and bone scanning the disease may be found incidentally imaging does not play a large part
on MR images, in the diagnosis
but MR at this
time. Dr. Chapman
disease, bone
emphasized
which involves
margin
is perhaps
finding
radiologic
the most
this disease:
in diagnosing
important
two
a wide variation
findings
of Paget
of focal disease.
The
important
site to examine margin is an of this disease; a “blade of
A V- or U-shaped
for the diagnosis
grass” margin is often found in younger
patients
(20-40
years
old). Another important phase i (the osteolytic subtle, but bone scans
sign is change in bone density. In phase), bone destruction may be allow early diagnosis by showing
changes
Osteolytic
in bone density.
particularly can cause
evident; difficulties
changes
in flat bones are
Paget disease occurring in diagnosis, but enlarged
one clue, and a clear-cut feature of the disease. enlarged and sclerotic bent cortex.
margin
in long bones bones provide
is once again a diagnostic
Other findings include altered arch, bone, and thickened and sometimes
When Paget disease involves a “bare area” (radiolucent area with no bone), the physician may have difficulty distinguishing the disease from tumor. In one such case, the CT numbers showed the abnormality to have the attenuation of fat, and the patient’s pain was relieved by steroid injections. On the other hand, the physician must stay alert for bare areas where they are not expected; one patient with such findings had a sarcoma with cortical destruction. Prominence of bony structures can also occur in Paget disease, and further imaging examinations may be needed to rule out
sarcoma
and to avoid biopsy.
Rheumatoid
Arthritis,
Psoriatic
Arthritis,
The distinctions rheumatoid
between
arthritis,
teoarthritis
were
Rheumatoid which
psoriatic
presented
the often confused entities of arthritis, and inflammatory osby William Martel (Ann Arbor).
arthritis
causes are characteristic,
juxtacortical bare-area but not specific. These
“wipe
of erosion.
out” the cortex
rather
When rheumatoid
articulating
surfaces,
than show
arthritis it almost
occurs
a discrete
eroero-
ofthe
disease),
and malalignment,
area
in a joint with
always
than one surface. The end stage of rheumatoid characterized by subchondral erosion, osteopenia
arthritis
and
Aeiter
syndrome.
Also,
occasionally
bone apposition
may obscure
bone erosion.
In psoriatic
ar-
thritis, the erosions occur in bare areas, and when these are associated with fuzzy bone apposition at the bases of the distal phalanges in the hands, they cause the “mouse ears” appearance. Erosions may be present without osteopenia, but in advanced disease, osteopenia is frequently present. In approximately 25% of patients with psoriatic arthritis, the “single-ray” pattern is seen (in which joints of one ray are selectively affected); also in 20-25% of patients, a polyarticular unilateral pattern appears that is virtually pathognomonic for psoriatic arthritis (as opposed to rheumatoid arthritis). A commonly affected joint in the foot is the interphalangeal joint of the great toe. Posterior calyceal spurs are often irregular
and indistinct
in outline
as contrasted
to spaces
with sharp
margins that may be seen in rheumatoid arthritis. Osteoarthritis usually affects both proximal and terminal joints; in erosive osteoarthritis, the striking inflammation may last for months and my be confusing to clinicians. However, some features that can help distinguish osteoarthritis include sparing of metacarpophalangeal joints and the pattern of subchondral rather than juxtachondral bone erosion. Also, in osteoarthritis, bone apposition is not common; when it does occur, it is linear and minimal and always associated with severe destruction of adjacent joints. It is never associated with fuzzy bone apposition, as is often seen in psoriatic arthritis.
of Osteoarthritis Forrester
(Los
Angeles) discussed the radiology the investigation of the underlying of cartilage. She first urged that physicians eliminate the concept that overuse of a joint can cause osteoarthritis; no evidence (e.g., studies on the hands of players of string instruments and on the feet of longdistance runners) indicates that placing great stress on a joint results in a higher incidence of this disease, and “even doctors who hate running” have been unable to prove that running causes osteoarthritis. Whereas rheumatoid arthritis is a synovial disease, osteoarthritis is a disease of the cartilage. Aadiologic findings of osteoarthritis include nonuniform cartilage loss and segmental cartilage narrowing; secondary to this denuded area, bone
of osteoarthritis, including cause for the destruction
sions occur in other articular diseases (but not in osteoarthritis). Erosion usually occurs earlier in the metacarpal areas than in the articulating phalanges. The erosive process may
multiple
in psoriatic
almost never occurs in osteoarthritis). occur in rheumatoid arthritis, but are rare
in rheumatoid arthritis, erosions develop in the feet before they develop in the hands; however, it is atypical for severe erosions to be present in the foot in the absence of any erosions in the hand. Periosteal bone apposition is typically absent in rheumatoid arthritis, but may be minimal (possibly at sites of tenosynovitis). Often confused with rheumatoid arthritis because arthritis may precede skin lesions, psoriatic arthritis differs from rheumatoid arthritis in its tendency to involve the terminal interphalangeal joints and produce bone apposition. Concomitant
Deborah
and Inflammatory
Osteoarthritis
simply
(volar subluxation Pseudocysts may
The Radiology
Arthritis
sions,
453
NEWS
affects more arthritis is
(a hallmark
often with volar subluxation
formations cysts. thritis,
result
in subchondral
sclerosis
and subchondral
When these features indicate the diagnosis of osteoarthe radiologist should then consider the causes of the
454
MEETING
disease and determine whether or secondary. Unfortunately, making these
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
difficult
or impossible.
Dr.
the osteoarthritis
is primary
determinations
is sometimes
described
a patient
with
may
not
reveal
the
cause.
In
one series, no clue was provided about the cause of degeneration but the classic progression of osteoarthritis was illustrated nicely: initial typical radiographic findings of superior segmental narrowing and subchondral cysts, followed 2 years later by not much change except for some change in the cysts, and then end-stage disease with huge osteophytes seen 4 years after the original radiograph. Given these difficulties, radiologists should look for specific evidence of secondary osteoarthritis: trauma, alteration of the articular surfaces so that they become incongruent (which leads to uneven wear and tear), and deposition of something in the cartilage to initiate the destruction with fissuring. In the case of a gunshot victim, one bullet caused osteoarthritis in
ways:
by avascular
necrosis
from the damage
actually done by the bullet and by lead arthropathy (which always leads to secondary degenerative disease). Abnormalities of articular surfaces seen in secondary osteoarthritis most commonly result from an untreated, congenital dislocated hip; a less common cause is avascular necrosis; and a very rate cause is spondyloepiphyseal dysplasia. Calcification in the cartilage provides a hint that cartilage deposition of crystals of pigmentation has occurred; the “Milwaukee shoulder” is a complication of hydroxyapatite deposition disease. Also, overgrowth of cartilage, rather than deposition in it, may cause joint degeneration. Neuropathic joints can look like osteoarthritis with absence of osteoporosis and presence of narrowing with little proliferative change. To distinguish between these two entities, the radiologist should check for the huge chronic effusions characteristic of neuropathic arthropathy. If these effusions can be tapped, they are noninflammatory, and this is diagnostic of neuropathy-a diagnosis that becomes even more evident as the neuropathic joints crumble, possibly within
weeks. MR Imaging
Adult
and
Skeletal
February
1992
limitations
end-stage hip disease, in whom the radiograph showed multiple metallic densities around the hip joint that represented acupuncture needles left in attempts to resolve hip pain over many years. One could not tell from this one film the cause of the disease; it may have resulted from infection, avascular necrosis, or treatment with remedies that contained prednisone. One expert (Hams) has hypothesized for years that end-stage hip disease without obvious cause is usually the result of unrecognized disease in childhood.
two distinct
AJR:i58,
in depicting fine details of structures with tightly hydrogen, such as bone, its inability to be used in patients who have pacemakers, and its high cost. MA imaging is an ideal tool for studying the anatomy of the hip: individual muscles and tendons can be identified better than with any other method. The use of multiplanar imaging enhances the depiction of many structures, especially tendons. MR findings in adult hip disease should be correlated with clinical and pathologic results to optimize diagnostic accuracy. Although MA results are highly sensitive for detecting abnormalities within high signal intensity marrow, the low signal intensity of the abnormalities is often nonspecific (trauma, tumor, and infection may all look similar). Also, the low signal intensity of active hematopoietic bone marrow may be mistaken to be abnormal. MA imaging can be used preoperatively to show marrow and soft-tissue extent of tumors; MA images can also identify skip lesions in the marrow and invasion of the hip joint. MA has a high sensitivity for detection of metastases, and can be used as an adjunct to radionuclide scanning and radiography in equivocal cases. For trauma to the adult hip, CT is more effective in depicting acetabular fractures and intraarticular fragments. However, MA images may show the viability of the bone marrow of the femoral head after its fracture and may be useful in showing injuries to ligaments and tendons. Also, MA imaging is capable of showing small fluid collections within and around the hip. In concluding, Dr. Bassett noted that, despite the advantages of MR imaging, it should be used routinely in adult hip disease but should be reserved for cases in which it can provide clinically useful information that is not available with less expensive methods.
bound
Forrester
Even a series of radiographs
NEWS
Diseases
Hip Diseases
In his discussion, Lawrence W. Bassett (Los Angeles) first listed the advantages of MA imaging in adult hip disease: the high sensitivity of MA in detection of bone marrow lesions (due to the high signal intensity of normal bone marrow); the inherently high contrast, resulting in exquisite depiction of soft-tissue structures, and the capability for direct imaging in any plane. The disadvantages of MA imaging include its
Detection
of Occult
Injuries
In her presentation, Dr. Frieda Feldman (New York, NY) focused on the use of MA imaging in cases of acute, severe, persistent lower back pain (especially in older patients). Her first example was that of a 60-year-old woman (5 years after a mastectomy) who arrived with several studies, including a hard-to-evaluate
pelvic
study
that
was
perhaps
suggestive
of
sclerosis; this study led to CT scanning, which in turn led to biopsy, interpretations of which ranged from diagnoses of metastases and primary tumor to nondiagnosis (“insufficient tissue”). Actually, the cause of this patient’s pain was an insufficiency stress fracture, and it was clearly identified by MR imaging. In another of many similar cases, a 50-year-old woman with lower back pain “came in with stacks of films and CTs done by the unwary” and a biopsy diagnosis of metastases; the MA image definitively showed the sacral fracture that was causing the pain. Dr. Feldman emphasized the importance of using MR imaging to ensure that stress fractures are not misdiagnosed as tumor and that identification of a possible insufficiency stress fracture can be aided by looking for associated fractures in typical locations, including the spine, pubic pelvis, and supraacetabular region. A traumatic hip fracture in a 70-year-old woman was missed on “initial, cost-conscious” tomograms. Coronal and axial MR images definitively identified the fracture and provided the
diagnosis.
Follow-up
corroborate
Downloaded from www.ajronline.org by 117.244.28.87 on 11/06/15 from IP address 117.244.28.87. Copyright ARRS. For personal use only; all rights reserved
MEETING
February 1992
AJR:158,
tomograms
the fracture.
(2-mm
The weakened
cuts)
still
femoral
failed
to
neck was
pinned on the strength of the MA findings. In the section of her talk that she called “the really esoteric, and occult: the skeletal symptom in search of a cause,” Dr. Feldman discussed those patients with vague plain films. She gave several cases in which tomograms were unable to provide diagnosis for symptomatic patients, so that MR im-
aging was requested as somewhat of a last resort. In one emergent case, a 50-year-old man with a painful knee effusion had inconclusive radiographic and tomographic studies; when MR imaging was done, the results revealed a “multitude of soft-tissue sins,” including the known effusion, a medial meniscal tear, abnormal signal in the posterior tibial plateau mdicating a fracture, along with an abnormal lateral ligament, increased buckling of the posterior cruciate ligament, absence of a definite anterior cruciate ligament, and a lateral meniscal
tear.
Based
concluded
Awards
on this and other
that MR imaging
experiences,
is a “heaven-sent
of the International
Skeletal
Dr. Feldman problem
solver.”
Society
Two awards are given at each annual meeting of this society: The highest award is the Founders Medal and the second
highest
The 155 Founders
is the Founders
Gold Medal
Walter BossIer (Winterthur, presented
the
Lecture.
Founders
Switzerland),
Medal
to John
the ISS president, A. Kirkpatrick, Jr.,
(Boston) a charter member of the ISS and its fourth president, whom Dr. Bessler described as a “perfect gentleman from top to toe.” Dr. Kirkpatrick was awarded this honor not only for his contributions to the 155 in particular and to the body of knowledge concerning skeletal radiology in general but
also for his publications (1 07 journal articles, 27 book chapters, and the book Orthopedic Diseases); his editorial services to many medical publications; his active memberships in other professional societies (including the John Caffey Society for Pediatric Radiology, the Fleischner Society, the American Roentgen Ray Society [past president, ARRS], The Society for Pediatric Radiology [past president, SPA], and honorary
memberships in 22 other societies); and his receipt Gold Medals of both the ARAS and the SPA.
of the
NEWS
455
Dr. Pitt began his Founders Lecture, “Rickets and Osteomalacia,” with a history of rickets, which he called our first
real “environmental monplace prevalence
is reflected
disease”
by a i 900 study
Lecture
For the second highest award, Michael J. Pitt (Tucson) gave the Founders Lecture in honor of Jack Edeiken (Houston), one of the three founders of the ISS.
Dr. Pitt’s introduction accomplishments
to his lecture focused
of Dr. Edeiken,
ing teacher, accomplished scholar nosis of Diseases of the Bones], friend.”
Besides
being
a founder
“superior
[author
on the life and
clinician,
outstand-
of Roentgen
founder of the ISS, of the ISS, Dr. Edeiken
Diag-
and has
held many other important posts in the organization, including secretary-treasurer and president. Dr. Pitt summarized Dr. Edeiken’s contribution to ISS by saying, “Without him, ISS would not be what it is today.”
it first became
corn-
the Industrial Revolution. Its in the early part of this century
that found
that 80% of infants
less than 2 years old in Boston had rickets. Vitamin Ddeficiency rickets virtually disappeared in the early 1 920s with the discovery and synthesis of vitamin D. Rickets refractory
to vitamin
D comprise
the cases seen by physicians
today.
(We now know that “vitamin D” is not a vitamin at all, but a prohormone formed naturally in the body that paradoxically both breaks down bone and creates new bone.) The terms rickets and osteomalacia represent a group of diseases with similar gross, radiologic, and histologic abnormalities; more than 50 reported diseases have changes characteristic of rickets and osteomalacia. Originally, these two diseases were considered separate entities, rickets occurring in the skeletally immature, and osteomalacia occurring in the cortical and spongy bone; they are, however, aspects of the same disease, and the physician needs to realize that rickets
and osteomalacia immature patients. systemic
coexist
diseases.
rickets
in the long
bones
of skeletally
Also, both rickets and osteomalacia Dr. Pitt also discussed the diagnosis
and osteomalacia.
In rickets,
the increase
are of
in the num-
ber of cells in the physeal zone of hypertrophy is haphazard (both in axial and latitudinal directions); also, there are fewer than normal cartilaginous bars laid down, and they cannot be mineralized. These characteristics contrast dramatically with the orderly columns in the normally developing growth plate. The radiologic diagnosis of rickets includes increased longitudinal and latitudinal radiolucency in the growth plate, decreased mineralization in the zones of primary and secondary spongiosa, and disorganization. In osteomalacia, the amount of bone is less than in the cortex of the normal medullary cavity, the canals are widened, and a pink-staining substance (osteoid seams) borders the canals. Radiologically, osteomalacia is characterized by osteopenia, decreased bone in cortex, Looser zones, osteoid accumulation, bending, and secondary hyperthyroidism. Finally, Dr. Pitt discussed the approach that the radiologist can take to discover the cause of diagnosed rickets or osteomalacia. Although many of the findings are nonspecific for any one disease in this group of diseases, he recommended a systematic consideration of the three main types of causes
for the diagnostician The ISS Founders
because
in England during in the United States
to consider:
difficulties,
including
or kidney
problems;
usually
phosphate
hypophosphatemia,
or tumor-associated with either tumors
(i)
gastrointestinal
(2) phosphate (a renal tubular uremic
D metabolism
vitamin
malabsorption
or calcium disorder,
osteopathy,
disorder, including or tumor treatment);
and liver
disorders-
such as X-linked Fanconi
disorders
syndrome,
associated
and (3) other (a small
of patients whose radiologic findings look like but who do not have biochemical features of rickets),
percentage
rickets including
cases
of metaphyseal
chondroplasia,
axial osteo-
malacia, and hyperphosphatasemia. Some characteristics seen in these categories are more specific than others, but using such systematic classification may help make the physician more comfortable with diagnosing and treating patients with the end-stage diseases of rickets and osteomalacia.
