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889
Meeting
News
“..
The Fleischner Society 22nd Annual Symposium Disease: Scientific Session, May 1992 Elizabeth
Whalen1
The Scientific
Session
of the 22nd
Annual
Symposium
on
Chest Disease presented by the Fleischner Society was held May 1 1 -1 2, 1992, at the Ch#{226}teau Launien, Ottawa, Canada. The Fleischner Society is, by its own description, “an international fellowship of radiologists, physicians, and scientists dedicated to advancing knowledge of the normal and diseased chest, and fostering chest radiology as an art and a science.” Preceding the Scientific Session, the annual Fleischner group
Society course was attended by a multidisciplinary of participants and offered sessions that encompassed
chest anatomy, pathology, physiology, and clinical management, as well as chest imaging. This course included plenary sessions, state-of-the-art sessions, lectures and refresher courses, focus sessions, “family feud” case presentations and film
analyses,
and the annual
Fleischnen
Lecture.
However, the Fleischnen Society annual course is not the subject of this report. The Scientific Session covered herea session open only to members and to the winner of the annual course
Fleischnen Memorial Award-followed the annual and featured the presentation of the paper that won
the award, along with presentations of papers by three new members of the society; also, members of the society presented 22 papers, including three case reports. Coverage of all the papers presented is impossible because of AJR page limitations;
synopses
on Chest
however,
the
following
summary
does
include
of the award paper, the three presentations by new and eight of the other presentations. The descnip-
members, tions of the talks
will be categorized
by general
topic:
specific
lung
diseases,
MR
and approaches
Specific
Lung
Solitary
imaging
of the chest,
in chest
and
new
technology
imaging.
Diseases
Pulmonary
Nodules
Probability of Malignancy Based on Bayesian Analyses.The winner of this year’s Memorial Fleischnen Award, Jud Gurney (Omaha, NB), presented a summary of a study by himself,
J. Mckay,
nancy
in solitary
Bayesian sidens
and
analysis.
Bayesian
all radiologic
and
nary
nodules,
these
istics
(e.g.,
calcification,
cavitation)
Bayes’ nodules
hemoptysis,
purpose
of the
on the
likelihood
of malig-
nodules
as calculated
by
analysis
is a technique
that con-
clinical
findings
findings.
include
growth,
and the patient’s
ing history, The
D. Lyddon
pulmonary
For
size,
and
previous was
(e.g.,
pulmo-
character-
location,
characteristics
study
solitary
the nodule’s
using
edge,
and
age, smok-
malignancy). to
investigate
the
use
of
theorem to predict malignancy of solitary pulmonary and to compare that prediction with the subjective
evaluation
by board-certified
radiologists.
First,
the
research-
ens derived the relevant likelihood ratios (which measure the degree of malignancy or benignity of a test result or clinical finding: likelihood ratio = [sensitivity]/[1 specificity]). Likelihood ratios were derived from a literature review. To be included in the literature review, a study must have been published within the last 30 years (1 962-1 992), must have -
Contributing editor, American Journal of Roentgenology, Ste. 1 03, 2223 Avenida de Ia Playa, La Jolla, CA 92037. Editor’s note.-”Meeting News” articles report the highlights of important national radiology meetings. The articles will not undergo the peer review usually required of AJR publications, nor will they offer a critique of the information provided. The sole purpose of the series 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. 1
AJR 159:889-895,
October
1992
036i-803X/92/1
594-0889
© American
Roentgen
Ray Society
MEETING
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890
included more than 1 00 nodules, and must have evaluated both benign and malignant nodules. Fifteen studies fulfilled all these criteria. Results from these studies were used to obtain likelihood ratios for radiologic and clinical characteristics. For example, two studies (n = 903) presented data on CT appearance of nodule edge (smooth, lobular, or inregular/spicu-
lated); from that data, likelihood ratios were calculated, showing a likelihood ratio of 0.37 for smooth edges, 0.60 for lobular edges, and 5.77 for irregular/spiculated edges. Intuitively, a likelihood
ratio
benignity
and
greater
chance
ratio
less
than
one indicates
a likelihood
of exactly
ratio
for malignancy one
do
a greater
greater
not
than
one
chance
of
indicates
a
(test results
with a likelihood
change
pretest
the
odds
of
NEWS
AJR:159,
Third,
in the
gists evaluated characterizing ings.
They
then
second
method
these same them according applied
October
of assessment,
two
1992
radiolo-
solitary pulmonary nodules by to radiologic and clinical find-
the previously
derived
likelihood
ratios
and Bayes’ theorem to estimate the probability of malignancy. Fourth, the accuracies of predictions of malignancy by the two groups were compared. The two readers who used Bayesian analysis more accurately assessed the probability of malignancy than did the four experts; the two also misclassified
fewer
nodules
as benign
(mean
of six misclassifications
vs mean of 1 6 misclassifications for the four experts). These data indicate that likelihood ratios and the use of Bayes’ theorem have potential for improving the accuracy of
malignancy; therefore, the data above translate into the qualitative statements that (1 ) smooth-edged nodules are more
predicting
the
Moreover,
if radiologists
benign than those with lobular edges and (2) irregular/spiculated edges are highly associated with malignancy. Likelihood ratios were calculated for clinical and nadiologic charactenistics, the most malignant of which were as follows: size >3.0 cm (likelihood ratio = 1 0.03), irregulan/spiculated edges on
malignancy (rather than using such terms as “most likely benign” or “possibly malignant”), physicians may better be able to determine the best course of patient care. Fractal analysis of solitary pulmonary nodules.-John H. M. Austin (New York, NY) introduced his presentation as a “tool talk,” saying that it looks like radiologists will be able to use fractal analysis based on thin-section CT to evaluate solitary pulmonary nodules, but this study is definitely a preliminary one. The word “fractal” is short for “fractional” and comes from the Latin “frangere” (meaning “to create irregular forms”). Fractals are irregularly shaped objects, and fractal geometry has been developed by Mandelbrot and others to study these objects. One example of a fractal is the island of Great Britain; to try to determine the length (L) of the entire coast of Great Britain, the equation in fractal geometry would be L = N x r, where r = the length of one ruler unit and N = number of units. Note that the shorter the ruler length, the higher the result will be for the length of the coast,
CT (5.77), hemoptysis (5.08), and previous malignancy (4.95). Second, after the likelihood ratios were derived for use in Bayes’ theorem, the researchers assessed the clinical and radiologic
findings
66
of
patients
with
solitary
pulmonary
nodules. Two groups assessed the data for probability of malignancy: (1) four expert academic radiologists (median experience, 24 years) used traditional methods of evaluation and (2) two observers (one academic radiologist and one resident-in-training) assessed the findings by using likelihood ratios. Of the 66 patients studied, 44 had malignant nodules
(32 bronchogenic
carcinoma,
nine metastases,
two carcinoid,
and one bronchoalveolar cell cancer); 22 had benign nodules (nine confirmed benign by biopsy, nine by presence of a benign pattern of calcification and absence of growth, and four by absence of growth over a minimum of 2 years). Findings among the study population include the following differences between those with malignant and benign solitary pulmonary nodules: the average ages of the patients were 66
and 59 years, benign
nodules
respectively, (not
smokers
(or ex-smokers)
and
average
the
for those
significantly
sizes
with
different);
malignant
and
percentages
of
were 57% and 37%, respectively; of nodules
were
2.4
and
1 .4 cm,
respectively.
For evaluating malignancy in the 66 patients, the following images were available: 156 individual chest radiognaphs, 57 CT scans, three fluoro/tomograms, and seven reference phantom studies. On the basis of the radiographic findings, the four expert radiologists subjectively decided whether the nodules were benign or malignant. Then, the experts were
asked to quantify (on a scale ranging from 1 to 100) their estimates as to whether the nodule identified was malignant. After this decision, the experts were provided with the patient’s
age and smoking
history
and were
asked,
“Does
this
change your decision?” If they answered “Yes,” they made a new quantitative estimate about the probable malignancy of the nodule. For nodules that proved to be malignant, the average
probability of malignancy given by the experts was 70%; for nodules that proved to be benign, the average probability of malignancy given by the experts was 18%.
i.e.,
N
malignancy
f(n). This
=
of
solitary
provide
function
pulmonary
a quantitative
is determined
fractional dimension D, which is characteristic shape, and yields L = k x nl_D.
nodules. probability
by the
of
noninteger
of the specific
In this work, Dr. Austin and coresearchers (J. Chen, F. Czegledy, J. katz, L. Boxt) examined 1 5 CT scans of nine solitary pulmonary nodules (parameters included the following: 1 .5-cm slice thickness, 1 3-cm field of view, use of bone algorithm, 1 :1 blow up, 1 4 x 1 7 in. film). After outlining the
shape of the lesion onto tracing
paper, the researchers
digi-
tized the image and, using a box-counting algorithm, calculated the fractional dimension, D. They found that they were able to assign to each image an individual D (mean r = .996 ± .001); the lowest D (1 .2346) was found for a smoothly rounded gnanuloma, and the highest D (1 .4287) for a spiculated alveolar cell carcinoma. These pilot results show the feasibility of using fractal analysis of the “coastline” of a solitary pulmonary nodule on
CT images; nodule Studies
however,
may prove are needed
the variability
D of a tumor and clinical variables, Respiratory
Distress
of the D of any individual
to limit the usefulness to investigate possible
of the analysis. correlates of the
e.g., prognosis.
Syndrome
Epithelial sodium transport in the developing lung: potential role in respiratory distress syndrome.-One of the new mem-
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AJR:159,
MEETING
October 1992
NEWS
891
bers of the society, Hugh O’Brodovich (Toronto, Canada) presented a hypothesis based on his work over the last 5-6 years: when neonates have inadequate lung epithelial sodium transport, this may be a pathogenic factor rather than a complication of respiratory distress syndrome. Fetal lungs are always filled with salt water at birth; abnormal clearance of this fluid leads to respiratory distress. Although fluid secretion promotes lung development, at some point secretion must be
and (2) dilate both shunt and normal regions, whereas nitric oxide would dilate normal regions but reduce shunt regions. After Dr. Zapol and coworkers had performed successful
stopped
studies in several ARDS patients with either chronic or acute pulmonary hypertension in which inhalation of nitric oxide (18
and
absorption
started
so that
the
formerly
water-
filled air space becomes an air-filled space for gas exchange. In a study using pregnant guinea pigs, Dr. O’Brodovich found that animals born with their lungs filled with the sodium transport blocker amilonide were blue and in respiratory distress; the degree to which fluid was blocked depended on the dose of amilonide. The experiment was repeated but sodium
channel
or other
sodium
transport
blockers
were was seen only in
given to some animals; respiratory distress those neonates whose mothers received the specific channel through
blocker, sodium
Observations
sodium
which confirmed that active sodium transport channels was a key to respiratory distress.
from further animal experiments
included
the
following: (1) fetal-derived alveolar epithelial cells were sodium-absonbing cells; (2) there are some high-amilonide affinity
preliminary studies in lambs (in which nitric oxide reduced experimentally induced pulmonary hypertension), nitric oxide
was used in hypoxic human infants and it raised arterial oxygen tensions in some infants within minutes of inhalation. Their
ppm)
hypotheses
were
confirmed
and IV prostacyclin
by
the
(4 ng/kg/min)
results
were
of
used.
their
Although
pulmonary pressure was reduced significantly by both methods, systemic pressure was reduced significantly only by IV prostacyclin (from 86 ± 13 to 79 ± 19 mm Hg); the reduction in systemic
pressure
significant
(from
with
85
±
nitric
oxide
1 2 to
82
was
±
not
statistically
1 3 mm
Hg).
The
IV
prostacyclin
treatment resulted in dilatation of the shunting lung regions (QS/QT increased from 36% ± 1 5 to 45% ± 13); however, nitric oxide decreased the shunt blood flow significantly (Q/Q1 decreased from 36% ± 1 5 to 31 % 14). Therefore, inhalation of nitric oxide by ARDS patients at a small, safe dose reduced pulmonary artery pressure without affecting systemic pressure and improved pulmonary gas
sodium channels, but there was evidence of additional members ofthefamily ofsodium channels; (3) each sodium channel has a “trap door” that opens and shuts, and its presence and characteristics can be determined by patch clamp electrophy-
exchange by redistributing blood flow away from shunting regions to normal regions. The safety of this dose of nitric oxide was shown by treatments in several patients who
siology;
effects.
and
(4) amiloride
inhibits
nonselective
cation
chan-
nels, which were found in fetal alveolar cells. Surfactant is also an important factor in lung development. In neonates, immature surfactant and immature ion transport may cause premature respiratory distress syndrome, although Dr. O’Brodovich is not dismissing other possible mechanisms for this disease. However, he did stress that doctors should be aware that ion transport is important in lung disease
and warrants
of future
study
channels,
RNA homology
further
in this area
C-section versus mechanisms.
investigation.
include
of sodium
pelvic delivery
Other
regulation channels,
areas
of sodium the effects
of
on lung fluid, and lung repair
Use of nitric oxide to reduce pulmonary hypertension and improve gas exchange in severe adult respiratory disease syndrome-Warren M. Zapol (Boston, MA) discussed a study in which he and his coworkers (R. Rossaint, K. Falke,
Berlin, Germany) investigated using inhalation of to help patients with adult respiratory disease (ARDS) and pulmonary hypertension. Although has been considered a toxic substance, the obtained positive results with tiny, nontoxic doses which
Environmental
Protection
Agency
nitric oxide syndrome nitric oxide researchers
( 2.1 in asthma patients; and 4 (n = 14), normal, PC20 > 8.0 in normal subjects. FEV1 increased more than 6% in 58% of group 1,
this relationship.
induced by oxygen radicals, but only at certain doses (for example, H2O2 at concentrations of 1 0_6 M or lower will induce a CBF inhibition that is reversible by protein kinase inhibitors, but at a concentration
AJR:159, October 1992
with cystic fibrosis to investigate the relationship the response to inhaled salbutamol and bronchial
hyperactivity, which was assessed by determining what concentration of inhaled methacholine would decrease FEV1 by 20% from baseline (PC20). In 50 children referred for confirmation of clinical suspicion of asthma and in 14 healthy control subjects, results of pulmonary function tests were within the normal range. On day 1 of the study, baseline pulmonary function tests were
assessment of the effects of radiotherapy/chemotherapy treatment (coauthors: S. Adachi, M. kusumoto, E. Sakai, M. Endo, k. Imanaka, M. Fujii, k. Yamasaki, E. Itouji). The three purposes of their study were as follows: to describe the gadolinium-enhanced MR appearance of lung cancer after
conservative treatment, to use gadolinium-enhanced MR imaging to differentiate residual or recurrent tumor from radiation pneumonitis, and to evaluate imaging the rate of reduction radiotherapy/chemotherapy.
Before and after treatment, enhanced
Ti -weighted
tients
had
(31
nocarcinoma
cell carcinoma).
squamous
and small
Three
evident: homogeneous squamous cell tumors,
by gadolinium-enhanced and necrosis resulting
unenhanced
MR images
and IV gadolinium-
were
obtained
cell carcinoma,
call carcinoma,
patterns
MR from
nine
each
and three
of tumor
in 52 pahad
ade-
had large
appearance
were
(which was seen after treatment in 13 four adenocarcinomas, six small cell
MEETING
AJR:159, October 1992
tumors, and one large cell tumor); mottled (which was seen after treatment in 10 squamous cell tumors, two adenocarcinomas, three small cell tumors, and one large cell tumor); and
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ninglike
(which
was
seen
after
treatment
in eight
squamous
cell carcinomas, three adenocarcinomas, no small cell carcinomas, and one large cell carcinoma). After treatment, gadolinium-enhanced MR imaging showed that, in 15 of the 24 homogeneous tumors, tumor size was less than or equal to 50% of its pretreatment size; a lower rate of reduction was found in the other nine homogeneous tumors. For mottled tumors, after conservative treatment, only four of 16 lesions had decreased more than 50% in size, and for ninglike tumors, a reduction of 50% or more was found in only three of 12 cases. The significance of reduction of tumor size is shown by survival rates: of the patients with homogeneous tumors, those whose tumors had decreased in size more
than
50%
survived
and those whose tumors 50% survived an average with
mottled
tumors,
whose
tumors
of 1 0.6 months,
those
whose
tumors
an average
had decreased
had decreased
of 12.5 months,
in size
less
than
in
and 50%
survived an average of 14.5 months. Finally, of the patients with ringlike tumors, those whose tumors had decreased in size more than 50% survived an average of 10.3 months, and those whose tumors had decreased in size less than 50% survived an average of 18.2 months. Therefore, this study showed that gadolinium-enhanced MR imaging had defined three lung tumor patterns and had shown the effects of conservative treatment on tumors with these patterns. Radiation pneumonitis occurred in 13 of the 52 cases. In 8% of these cases, tumor enhanced more than the pneumonitis. In 23%, enhancement was equal, and monitis enhanced more than tumor. Moreover, linium-enhanced MR images, viable tumor
in 69%, pneuon the gadodid enhance,
necrotizing areas either did not enhance or showed delayed enhancement, and radiation pneumonitis showed remarkable enhancement. Thus, gadolinium-enhanced MR imaging did help differentiate recurrent tumor from radiation pneumonitis. These researchers also performed MR spectroscopy on some of these patients for follow-up studies. MR spectroscopy may prove helpful in delineating even further the therapeutic effects of radiotherapy and chemotherapy on lung cancer.
MR Imaging
in Venous
A prospective conventional
Thromboembolic
Disease
study of 61 consecutive
venography
was
patients
presented
referred
for
by H. Dink Sostman
NC; coauthors: A. S. Evans, J. R. MacFall, T. k. F. Foo, J. F. Debatin, C. E. Spritzer, T. M. Grist). In these
(Dunham,
patients, both conventional venography performed within 1 2 hr (mean, 2.6
and MR imaging hr). MR images
were were
obtained first in 43% of cases, and conventional venograms were obtained first in 57% of cases. Results of all the imaging studies
were
conventional was
considered
interpreted
blindly.
If both
MR
venography
findings
were
positive,
if both
MR
a true
positive;
imaging
and
the result imaging
893
conventional
and
venognaphy
findings
were
negative,
the result
was considered a true negative. In cases in which MR imaging results disagreed with those of conventional venography concerning thromboembolic disease in the calf and/or thigh, results
from
conventional
venography
were
considered
con-
rect and MR imaging results were considered incorrect. However, in cases of pelvic vein disease, the correctness of discordant results was determined by direct puncture of femoral vein or follow-up. As stated above, conventional venography was considered to be the gold standard for detecting thromboembolic in the thigh and calf veins. In thigh veins, MR imaging
disease showed
a sensitivity of 100% and a specificity of 100%. However, the values were somewhat lower for MR imaging in calf veins (sensitivity, 87%; specificity, 97%). In pelvic veins, the sensitivity of MR imaging was 100%; for conventional venography, sensitivities
had decreased in size less than of 1 7.2 months. Of the patients
size more than 50% survived those
an average
NEWS
were
78%
by direct
up confirmations.
Specificity
for conventional
venography;
puncture
or 64%
by follow-
for pelvic vein disease was 100% for
MR
imaging,
specificities
were 95% by direct puncture or 98% by follow-up confirmations. In summary, for assessing deep vein thrombosis, MR imaging
is less sensitive
than conventional
veins, equal to conventional
venography
venography
in assessing
in thigh veins, and more sensitive than conventional raphy in assessing disease in the pelvic veins.
in calf
disease venog-
Dr. Sostman also discussed promising trends in the use of MR imaging of pulmonary circulation in the evaluation of pulmonary emboli. In one example, a three-dimensional MR data set from a dog model showed the advantage of the ability to change the plane and angle different parts of the vessels. Possible
in order to examine new techniques en-
compass vascular imaging, thrombus imaging, two-dimensional and three-dimensional techniques, cine MR imaging, breathhold procedures, and black-blood methods.
Three-dimensional Left Ventricular
MR Tagging to Indicate Myocardial Strain
Elias A. Zerhouni
Veigh, C. Moore)
(Baltimore,
MD) and colleagues
used three-dimensional
of
(E. Mc-
(3D) MR tagging
try to resolve a long-standing that is, the inability
Homogeneity
problem in cardiac to measure the deformation
to
physiologyof the heart.
In the study of an object such as the heart, which generates force, one needs to know its mechanical properties and to understand exactly its deformation. Because in traditional
imaging methods,
the heart moves through
the imaging
plane,
the point-to-point vestigate whether
deformation cannot be determined. left ventricular strain is temporally
To inand
spatially
heterogeneous
in the normal heart (as suggested by and implanted bead these researchers “tagged” the heart by labeling little
angiocardiographic,
studies), planes
echocardiographic,
in six directions
entire ventricle
(1 2 segments)
in three dimensions.
and then examined
the
After they had obtained
all the MR images needed, they defined the volume elements in the computer and performed a complete finite strain analysis to study the strain in the radial, longitudinal, and circumferential directions and to therefore obtain a “map” of the
deformation
of the heart in all directions.
A color scale was
MEETING
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894
used for display, in which blue indicated the lowest amount of strain and yellow (red/yellow) the highest amount of strain. By use of this method in 12 normal subjects, an enormous amount of heterogeneity of deformation was seen from the start (no stress, diastole) to strain (systole) of the heart cycle. The strain in the radial direction was very heterogeneous; however, the deformation was homogeneous in the longitudinal or circumferential directions. Moreover, despite the lack of change in total volume of the heart, changes were found in single-volume elements. Therefore, Dr. Zerhouni and colleagues concluded that the heterogeneity seen must be the result of an error introduced in the radial direction in measuring endocardial surface. When the error in the radial direction was corrected
(i.e., when
the volume
was
maintained),
they
found that the normal heart contracted homogeneously. This need for correction in the radial direction in assessing the heterogeneity of heart contraction indicates two things: tremendous uncertainty still exists as to the location of the endocardium
on MR
differently
images,
and the endocandium
may
NEWS
AJR:159,
and sometimes
airways
Dynamic,
and Approaches
uation
with
exhalation,
Ultrafast,
High-Resolution
with bronchiolitis
exhalation
obliterans,
in a patient
new technique to be resolved
by W.
Richard
CT of the Lung
Webb
E. J. Stern,
G. Gamsu).
lution
CT involves
obtaining
(San
Francisco,
Dynamic,
CA;
ultrafast
10 1 00-msec
coau-
high-reso-
high-resolution
CT
scans in 6 sec while the patient performs a forced vital capacity maneuver. The scans are evaluated qualitatively by viewing the scan sequence in the “movie mode, noting the lung-attenuation changes and volume changes during exhal“
ation,
and selecting
for analysis
regions
of interest
to show air trapping. Quantitative evaluation attenuation curves, lung-attenuation values units)
plotted
vs time
for
selected
regions
that appear
includes time(in Hounsfield of interest,
and
changes in lung attenuation from maximum inhalation to maximum exhalation. Dynamic, ultrafast, high-resolution CT scans of the lung were obtained in 1 0 healthy, nonsmoking men with normal spirometry results. The increase in lung-attenuation values from maximum inhalation to maximum exhalation ranged from 84 to 372 H (average, 200 H). Also, with one exception in the normal subjects, the dependent lung showed a greater increase during exhalation than did the nondependent lungthis held true for all areas of the lung and for both prone and supine positions. In patients namic,
with
ultrafast,
obstructive
lung disease,
high-resolution
CT
studies
showed
an
with
dy-
increase
in
lung-attenuation values that averaged only about 50 H from maximum inhalation to maximum exhalation; moreover, in some patients, lung-attenuation values decreased from maximum inhalation to maximum exhalation. This technique detected
air trapping
ary lobule,
in the
bronchial
lung
collapse
that
was
as small
associated
In a patient
and it showed
air trapping
with endobronchial
with
during
metastasis.
This
appears to be very promising, and issues still include explanations for air trapping in normal
subjects and for the decrease exhalation in some patients.
in lung-attenuation
values
on
Thoracocardiography
tions)
thors,
airways.
A. Sackner
(Miami
discussed
Beach,
FL;
coauthons,
K. E.
the use of thonacocardiography
for the noninvasive assessment of ventricular diastolic function and its respiratory variation. If an inductive plethysmographic transducer is placed around the nib cage below on near the ziphoid process, “little lumps” (candiogenic oscilla-
Imaging
A study of a new technique for diagnosing lung diseases characterized by airways obstruction and air trapping was described
and patent
lymphangitic carcinomatosis, dynamic, ultrafast, high-resolution CT showed bronchial occlusion and subsegmental air trapping on exhalation. Dynamic, ultrafast, high-resolution CT showed secondary pulmonary lobular air trapping in patients
Marvin
in Chest
in pa-
move
than does the nest of the heart.
Technologies
and air trapping
tients with normal pulmonary function tests. On dynamic, ultrafast, high-resolution CT, normal lung had homogeneous parenchyma, homogeneous increase in atten-
Bloch, S. Jungoon) New
obstruction
1992
October
as a second-
with air trapping,
are
shown
oscillations,
on the
respiratory
curve;
these
candiogenic
which have been
known about for many years, constitute up to 4% of the total respiratory signal. Candiogenic oscillations increased with inspiration (and decreased with expiration) ifthe transducer band was placed below the nipple line; the reverse was true (oscillations decreased with inspiration and increased with expiration) when the transducer band was placed below the xiphoid. These researchers there-
fore concluded that, by placing the band in different locations, they could judge whether they were measuring the volume of the left on night ventricle. In 1 2 normal subjects, function were obtained
then compared literature.
with the same measures
For example,
on inspiration
several measures of left ventricular by use of thoracocardiognaphy and
and expiration
were compared
as reported
thonacocardiognaphic
stroke
of 1 .0- and
with baseline
stroke
1 .5-I tidal
volumes
in the volumes
volumes
of 0.5 I. At 1.5
I, stroke volume on inspiration was 84% of baseline, stroke volume on expiration was 1 26% of baseline, and average stroke volume was 1 03% of baseline. Also at 1 .5-I tidal
volumes, isovolumic relaxation time on inspiration was 77 msec; on expiration, 82 msec; and on average, 83 msec, all of which were comparable with measurements obtained by Doppler echo studies. Other measurements obtained by thoracocandiography were heart rate, early filling rate/atnial filling
rate, early filling rate/stroke volume, and atnial filling rate/ stroke volume. Moreover, imposed mechanical ventilation showed reversed respiratory amplitudes on thonacocandiography (e.g., with mechanical the left ventricle is greaten
Dr. Sackner
pointed
ventilation, on inspiration
the stroke volume of than on expiration).
out that, if such values can be obtained
accurately by the noninvasive method of thoracocandiognaphy, wedge pressure could be indirectly calculated and,
in
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AJR:159,
MEETING
1992
October
some cases, use of the Swan-Ganz catheter could therefore be avoided. Finally, in 1 0 normal subjects, thoracocardiognaphic results were compared with those from an automatic edge detector echocardiographic device (HP-Somnos 1500). (Dr. Sackner noted that this part of the study took 1 .5 days to perform and 3 months to analyze because of the difficulty of translating HP-Somnos data to analog values.) Stroke volumes found with
the two
methods
were
within
20%
of each
other,
good
agreement was found in both inspiratory and expiratory stroke volumes, the mean difference in isovolumic relaxation time between the two methods was only 2 msec, and the mean difference in peak and atrial filling rates between the two methods was zero. These researchers concluded that thoracocardiography can measure the function of the right on left ventricle both accurately
and
noninvasively.
Furthermore,
they
found
that
their normal values obtained by thoracocardiography for isovolumic relaxation time and early filling rate/atrial filling rate agreed closely with those published in the literature.
NEWS
895
racic Society has provided guidelines for obtaining measures of peak expiratory flow and forced expiratory volume at 1 sec (FEV1), no instructions are given concerning the inspiratory pattern
before
the
forced
expiration.
Course
of Maximal
of Preceding
Flow-Volume
Curves
on Time
Inspiration
A study on maximal expiratory flow-volume maneuvers was by E. D’Angelo(Milan, Italy), E. Prandi (Milan, Italy), and J. Milic-Emili (Montreal, Quebec, Canada) and presented to the society by Dr. Milic-Emili. Although the American Thoperformed
these
re-
vital capacity maneuvers after four different inspiratory maneuvers: 1 , breathe in as fast as possible and then breathe out immediately and as quickly as possible; 2, breathe in as
fast as possible, hold your breath for quickly; 3, breathe in slowly, do not breathe out quickly; and 4, breathe in for 5 sec, then breathe out quickly. In all subjects, the results of the
5 sec, then breathe out hold your breath, then slowly, hold your breath test were similar:
peak
flow and FEV1 were significantly higher with maneuver 1 than with any other inspiratory maneuver and were lowest with
maneuvers both
FEV025
2 and 4. Similar and FEV0.
differences
(forced
and 0.50 sec). Such results Dependence
Therefore,
searchers conducted a study in 13 naive medical students in which volume was measured with body plethysmography and flow was measured at the mouth with a heated Fleisch pneumotachograph. Each subject performed forced expired
could
expiratory
were
also seen in
volumes
be explained
at 0.25
by a simple
viscoelastic model of the respiratory system that was introduced 50 years ago. The data provided by this study indicate that standardization of the forced vital capacity maneuver must take into account the pattern of the preceding inspiration. With such standardization, the measurements will be more reproducible and comparable than they are currently.
889
Meeting
News
“..
The Fleischner Society 22nd Annual Symposium Disease: Scientific Session, May 1992 Elizabeth
Whalen1
The Scientific
Session
of the 22nd
Annual
Symposium
on
Chest Disease presented by the Fleischner Society was held May 1 1 -1 2, 1992, at the Ch#{226}teau Launien, Ottawa, Canada. The Fleischner Society is, by its own description, “an international fellowship of radiologists, physicians, and scientists dedicated to advancing knowledge of the normal and diseased chest, and fostering chest radiology as an art and a science.” Preceding the Scientific Session, the annual Fleischner group
Society course was attended by a multidisciplinary of participants and offered sessions that encompassed
chest anatomy, pathology, physiology, and clinical management, as well as chest imaging. This course included plenary sessions, state-of-the-art sessions, lectures and refresher courses, focus sessions, “family feud” case presentations and film
analyses,
and the annual
Fleischnen
Lecture.
However, the Fleischnen Society annual course is not the subject of this report. The Scientific Session covered herea session open only to members and to the winner of the annual course
Fleischnen Memorial Award-followed the annual and featured the presentation of the paper that won
the award, along with presentations of papers by three new members of the society; also, members of the society presented 22 papers, including three case reports. Coverage of all the papers presented is impossible because of AJR page limitations;
synopses
on Chest
however,
the
following
summary
does
include
of the award paper, the three presentations by new and eight of the other presentations. The descnip-
members, tions of the talks
will be categorized
by general
topic:
specific
lung
diseases,
MR
and approaches
Specific
Lung
Solitary
imaging
of the chest,
in chest
and
new
technology
imaging.
Diseases
Pulmonary
Nodules
Probability of Malignancy Based on Bayesian Analyses.The winner of this year’s Memorial Fleischnen Award, Jud Gurney (Omaha, NB), presented a summary of a study by himself,
J. Mckay,
nancy
in solitary
Bayesian sidens
and
analysis.
Bayesian
all radiologic
and
nary
nodules,
these
istics
(e.g.,
calcification,
cavitation)
Bayes’ nodules
hemoptysis,
purpose
of the
on the
likelihood
of malig-
nodules
as calculated
by
analysis
is a technique
that con-
clinical
findings
findings.
include
growth,
and the patient’s
ing history, The
D. Lyddon
pulmonary
For
size,
and
previous was
(e.g.,
pulmo-
character-
location,
characteristics
study
solitary
the nodule’s
using
edge,
and
age, smok-
malignancy). to
investigate
the
use
of
theorem to predict malignancy of solitary pulmonary and to compare that prediction with the subjective
evaluation
by board-certified
radiologists.
First,
the
research-
ens derived the relevant likelihood ratios (which measure the degree of malignancy or benignity of a test result or clinical finding: likelihood ratio = [sensitivity]/[1 specificity]). Likelihood ratios were derived from a literature review. To be included in the literature review, a study must have been published within the last 30 years (1 962-1 992), must have -
Contributing editor, American Journal of Roentgenology, Ste. 1 03, 2223 Avenida de Ia Playa, La Jolla, CA 92037. Editor’s note.-”Meeting News” articles report the highlights of important national radiology meetings. The articles will not undergo the peer review usually required of AJR publications, nor will they offer a critique of the information provided. The sole purpose of the series 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. 1
AJR 159:889-895,
October
1992
036i-803X/92/1
594-0889
© American
Roentgen
Ray Society
MEETING
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890
included more than 1 00 nodules, and must have evaluated both benign and malignant nodules. Fifteen studies fulfilled all these criteria. Results from these studies were used to obtain likelihood ratios for radiologic and clinical characteristics. For example, two studies (n = 903) presented data on CT appearance of nodule edge (smooth, lobular, or inregular/spicu-
lated); from that data, likelihood ratios were calculated, showing a likelihood ratio of 0.37 for smooth edges, 0.60 for lobular edges, and 5.77 for irregular/spiculated edges. Intuitively, a likelihood
ratio
benignity
and
greater
chance
ratio
less
than
one indicates
a likelihood
of exactly
ratio
for malignancy one
do
a greater
greater
not
than
one
chance
of
indicates
a
(test results
with a likelihood
change
pretest
the
odds
of
NEWS
AJR:159,
Third,
in the
gists evaluated characterizing ings.
They
then
second
method
these same them according applied
October
of assessment,
two
1992
radiolo-
solitary pulmonary nodules by to radiologic and clinical find-
the previously
derived
likelihood
ratios
and Bayes’ theorem to estimate the probability of malignancy. Fourth, the accuracies of predictions of malignancy by the two groups were compared. The two readers who used Bayesian analysis more accurately assessed the probability of malignancy than did the four experts; the two also misclassified
fewer
nodules
as benign
(mean
of six misclassifications
vs mean of 1 6 misclassifications for the four experts). These data indicate that likelihood ratios and the use of Bayes’ theorem have potential for improving the accuracy of
malignancy; therefore, the data above translate into the qualitative statements that (1 ) smooth-edged nodules are more
predicting
the
Moreover,
if radiologists
benign than those with lobular edges and (2) irregular/spiculated edges are highly associated with malignancy. Likelihood ratios were calculated for clinical and nadiologic charactenistics, the most malignant of which were as follows: size >3.0 cm (likelihood ratio = 1 0.03), irregulan/spiculated edges on
malignancy (rather than using such terms as “most likely benign” or “possibly malignant”), physicians may better be able to determine the best course of patient care. Fractal analysis of solitary pulmonary nodules.-John H. M. Austin (New York, NY) introduced his presentation as a “tool talk,” saying that it looks like radiologists will be able to use fractal analysis based on thin-section CT to evaluate solitary pulmonary nodules, but this study is definitely a preliminary one. The word “fractal” is short for “fractional” and comes from the Latin “frangere” (meaning “to create irregular forms”). Fractals are irregularly shaped objects, and fractal geometry has been developed by Mandelbrot and others to study these objects. One example of a fractal is the island of Great Britain; to try to determine the length (L) of the entire coast of Great Britain, the equation in fractal geometry would be L = N x r, where r = the length of one ruler unit and N = number of units. Note that the shorter the ruler length, the higher the result will be for the length of the coast,
CT (5.77), hemoptysis (5.08), and previous malignancy (4.95). Second, after the likelihood ratios were derived for use in Bayes’ theorem, the researchers assessed the clinical and radiologic
findings
66
of
patients
with
solitary
pulmonary
nodules. Two groups assessed the data for probability of malignancy: (1) four expert academic radiologists (median experience, 24 years) used traditional methods of evaluation and (2) two observers (one academic radiologist and one resident-in-training) assessed the findings by using likelihood ratios. Of the 66 patients studied, 44 had malignant nodules
(32 bronchogenic
carcinoma,
nine metastases,
two carcinoid,
and one bronchoalveolar cell cancer); 22 had benign nodules (nine confirmed benign by biopsy, nine by presence of a benign pattern of calcification and absence of growth, and four by absence of growth over a minimum of 2 years). Findings among the study population include the following differences between those with malignant and benign solitary pulmonary nodules: the average ages of the patients were 66
and 59 years, benign
nodules
respectively, (not
smokers
(or ex-smokers)
and
average
the
for those
significantly
sizes
with
different);
malignant
and
percentages
of
were 57% and 37%, respectively; of nodules
were
2.4
and
1 .4 cm,
respectively.
For evaluating malignancy in the 66 patients, the following images were available: 156 individual chest radiognaphs, 57 CT scans, three fluoro/tomograms, and seven reference phantom studies. On the basis of the radiographic findings, the four expert radiologists subjectively decided whether the nodules were benign or malignant. Then, the experts were
asked to quantify (on a scale ranging from 1 to 100) their estimates as to whether the nodule identified was malignant. After this decision, the experts were provided with the patient’s
age and smoking
history
and were
asked,
“Does
this
change your decision?” If they answered “Yes,” they made a new quantitative estimate about the probable malignancy of the nodule. For nodules that proved to be malignant, the average
probability of malignancy given by the experts was 70%; for nodules that proved to be benign, the average probability of malignancy given by the experts was 18%.
i.e.,
N
malignancy
f(n). This
=
of
solitary
provide
function
pulmonary
a quantitative
is determined
fractional dimension D, which is characteristic shape, and yields L = k x nl_D.
nodules. probability
by the
of
noninteger
of the specific
In this work, Dr. Austin and coresearchers (J. Chen, F. Czegledy, J. katz, L. Boxt) examined 1 5 CT scans of nine solitary pulmonary nodules (parameters included the following: 1 .5-cm slice thickness, 1 3-cm field of view, use of bone algorithm, 1 :1 blow up, 1 4 x 1 7 in. film). After outlining the
shape of the lesion onto tracing
paper, the researchers
digi-
tized the image and, using a box-counting algorithm, calculated the fractional dimension, D. They found that they were able to assign to each image an individual D (mean r = .996 ± .001); the lowest D (1 .2346) was found for a smoothly rounded gnanuloma, and the highest D (1 .4287) for a spiculated alveolar cell carcinoma. These pilot results show the feasibility of using fractal analysis of the “coastline” of a solitary pulmonary nodule on
CT images; nodule Studies
however,
may prove are needed
the variability
D of a tumor and clinical variables, Respiratory
Distress
of the D of any individual
to limit the usefulness to investigate possible
of the analysis. correlates of the
e.g., prognosis.
Syndrome
Epithelial sodium transport in the developing lung: potential role in respiratory distress syndrome.-One of the new mem-
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AJR:159,
MEETING
October 1992
NEWS
891
bers of the society, Hugh O’Brodovich (Toronto, Canada) presented a hypothesis based on his work over the last 5-6 years: when neonates have inadequate lung epithelial sodium transport, this may be a pathogenic factor rather than a complication of respiratory distress syndrome. Fetal lungs are always filled with salt water at birth; abnormal clearance of this fluid leads to respiratory distress. Although fluid secretion promotes lung development, at some point secretion must be
and (2) dilate both shunt and normal regions, whereas nitric oxide would dilate normal regions but reduce shunt regions. After Dr. Zapol and coworkers had performed successful
stopped
studies in several ARDS patients with either chronic or acute pulmonary hypertension in which inhalation of nitric oxide (18
and
absorption
started
so that
the
formerly
water-
filled air space becomes an air-filled space for gas exchange. In a study using pregnant guinea pigs, Dr. O’Brodovich found that animals born with their lungs filled with the sodium transport blocker amilonide were blue and in respiratory distress; the degree to which fluid was blocked depended on the dose of amilonide. The experiment was repeated but sodium
channel
or other
sodium
transport
blockers
were was seen only in
given to some animals; respiratory distress those neonates whose mothers received the specific channel through
blocker, sodium
Observations
sodium
which confirmed that active sodium transport channels was a key to respiratory distress.
from further animal experiments
included
the
following: (1) fetal-derived alveolar epithelial cells were sodium-absonbing cells; (2) there are some high-amilonide affinity
preliminary studies in lambs (in which nitric oxide reduced experimentally induced pulmonary hypertension), nitric oxide
was used in hypoxic human infants and it raised arterial oxygen tensions in some infants within minutes of inhalation. Their
ppm)
hypotheses
were
confirmed
and IV prostacyclin
by
the
(4 ng/kg/min)
results
were
of
used.
their
Although
pulmonary pressure was reduced significantly by both methods, systemic pressure was reduced significantly only by IV prostacyclin (from 86 ± 13 to 79 ± 19 mm Hg); the reduction in systemic
pressure
significant
(from
with
85
±
nitric
oxide
1 2 to
82
was
±
not
statistically
1 3 mm
Hg).
The
IV
prostacyclin
treatment resulted in dilatation of the shunting lung regions (QS/QT increased from 36% ± 1 5 to 45% ± 13); however, nitric oxide decreased the shunt blood flow significantly (Q/Q1 decreased from 36% ± 1 5 to 31 % 14). Therefore, inhalation of nitric oxide by ARDS patients at a small, safe dose reduced pulmonary artery pressure without affecting systemic pressure and improved pulmonary gas
sodium channels, but there was evidence of additional members ofthefamily ofsodium channels; (3) each sodium channel has a “trap door” that opens and shuts, and its presence and characteristics can be determined by patch clamp electrophy-
exchange by redistributing blood flow away from shunting regions to normal regions. The safety of this dose of nitric oxide was shown by treatments in several patients who
siology;
effects.
and
(4) amiloride
inhibits
nonselective
cation
chan-
nels, which were found in fetal alveolar cells. Surfactant is also an important factor in lung development. In neonates, immature surfactant and immature ion transport may cause premature respiratory distress syndrome, although Dr. O’Brodovich is not dismissing other possible mechanisms for this disease. However, he did stress that doctors should be aware that ion transport is important in lung disease
and warrants
of future
study
channels,
RNA homology
further
in this area
C-section versus mechanisms.
investigation.
include
of sodium
pelvic delivery
Other
regulation channels,
areas
of sodium the effects
of
on lung fluid, and lung repair
Use of nitric oxide to reduce pulmonary hypertension and improve gas exchange in severe adult respiratory disease syndrome-Warren M. Zapol (Boston, MA) discussed a study in which he and his coworkers (R. Rossaint, K. Falke,
Berlin, Germany) investigated using inhalation of to help patients with adult respiratory disease (ARDS) and pulmonary hypertension. Although has been considered a toxic substance, the obtained positive results with tiny, nontoxic doses which
Environmental
Protection
Agency
nitric oxide syndrome nitric oxide researchers
( 2.1 in asthma patients; and 4 (n = 14), normal, PC20 > 8.0 in normal subjects. FEV1 increased more than 6% in 58% of group 1,
this relationship.
induced by oxygen radicals, but only at certain doses (for example, H2O2 at concentrations of 1 0_6 M or lower will induce a CBF inhibition that is reversible by protein kinase inhibitors, but at a concentration
AJR:159, October 1992
with cystic fibrosis to investigate the relationship the response to inhaled salbutamol and bronchial
hyperactivity, which was assessed by determining what concentration of inhaled methacholine would decrease FEV1 by 20% from baseline (PC20). In 50 children referred for confirmation of clinical suspicion of asthma and in 14 healthy control subjects, results of pulmonary function tests were within the normal range. On day 1 of the study, baseline pulmonary function tests were
assessment of the effects of radiotherapy/chemotherapy treatment (coauthors: S. Adachi, M. kusumoto, E. Sakai, M. Endo, k. Imanaka, M. Fujii, k. Yamasaki, E. Itouji). The three purposes of their study were as follows: to describe the gadolinium-enhanced MR appearance of lung cancer after
conservative treatment, to use gadolinium-enhanced MR imaging to differentiate residual or recurrent tumor from radiation pneumonitis, and to evaluate imaging the rate of reduction radiotherapy/chemotherapy.
Before and after treatment, enhanced
Ti -weighted
tients
had
(31
nocarcinoma
cell carcinoma).
squamous
and small
Three
evident: homogeneous squamous cell tumors,
by gadolinium-enhanced and necrosis resulting
unenhanced
MR images
and IV gadolinium-
were
obtained
cell carcinoma,
call carcinoma,
patterns
MR from
nine
each
and three
of tumor
in 52 pahad
ade-
had large
appearance
were
(which was seen after treatment in 13 four adenocarcinomas, six small cell
MEETING
AJR:159, October 1992
tumors, and one large cell tumor); mottled (which was seen after treatment in 10 squamous cell tumors, two adenocarcinomas, three small cell tumors, and one large cell tumor); and
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ninglike
(which
was
seen
after
treatment
in eight
squamous
cell carcinomas, three adenocarcinomas, no small cell carcinomas, and one large cell carcinoma). After treatment, gadolinium-enhanced MR imaging showed that, in 15 of the 24 homogeneous tumors, tumor size was less than or equal to 50% of its pretreatment size; a lower rate of reduction was found in the other nine homogeneous tumors. For mottled tumors, after conservative treatment, only four of 16 lesions had decreased more than 50% in size, and for ninglike tumors, a reduction of 50% or more was found in only three of 12 cases. The significance of reduction of tumor size is shown by survival rates: of the patients with homogeneous tumors, those whose tumors had decreased in size more
than
50%
survived
and those whose tumors 50% survived an average with
mottled
tumors,
whose
tumors
of 1 0.6 months,
those
whose
tumors
an average
had decreased
had decreased
of 12.5 months,
in size
less
than
in
and 50%
survived an average of 14.5 months. Finally, of the patients with ringlike tumors, those whose tumors had decreased in size more than 50% survived an average of 10.3 months, and those whose tumors had decreased in size less than 50% survived an average of 18.2 months. Therefore, this study showed that gadolinium-enhanced MR imaging had defined three lung tumor patterns and had shown the effects of conservative treatment on tumors with these patterns. Radiation pneumonitis occurred in 13 of the 52 cases. In 8% of these cases, tumor enhanced more than the pneumonitis. In 23%, enhancement was equal, and monitis enhanced more than tumor. Moreover, linium-enhanced MR images, viable tumor
in 69%, pneuon the gadodid enhance,
necrotizing areas either did not enhance or showed delayed enhancement, and radiation pneumonitis showed remarkable enhancement. Thus, gadolinium-enhanced MR imaging did help differentiate recurrent tumor from radiation pneumonitis. These researchers also performed MR spectroscopy on some of these patients for follow-up studies. MR spectroscopy may prove helpful in delineating even further the therapeutic effects of radiotherapy and chemotherapy on lung cancer.
MR Imaging
in Venous
A prospective conventional
Thromboembolic
Disease
study of 61 consecutive
venography
was
patients
presented
referred
for
by H. Dink Sostman
NC; coauthors: A. S. Evans, J. R. MacFall, T. k. F. Foo, J. F. Debatin, C. E. Spritzer, T. M. Grist). In these
(Dunham,
patients, both conventional venography performed within 1 2 hr (mean, 2.6
and MR imaging hr). MR images
were were
obtained first in 43% of cases, and conventional venograms were obtained first in 57% of cases. Results of all the imaging studies
were
conventional was
considered
interpreted
blindly.
If both
MR
venography
findings
were
positive,
if both
MR
a true
positive;
imaging
and
the result imaging
893
conventional
and
venognaphy
findings
were
negative,
the result
was considered a true negative. In cases in which MR imaging results disagreed with those of conventional venography concerning thromboembolic disease in the calf and/or thigh, results
from
conventional
venography
were
considered
con-
rect and MR imaging results were considered incorrect. However, in cases of pelvic vein disease, the correctness of discordant results was determined by direct puncture of femoral vein or follow-up. As stated above, conventional venography was considered to be the gold standard for detecting thromboembolic in the thigh and calf veins. In thigh veins, MR imaging
disease showed
a sensitivity of 100% and a specificity of 100%. However, the values were somewhat lower for MR imaging in calf veins (sensitivity, 87%; specificity, 97%). In pelvic veins, the sensitivity of MR imaging was 100%; for conventional venography, sensitivities
had decreased in size less than of 1 7.2 months. Of the patients
size more than 50% survived those
an average
NEWS
were
78%
by direct
up confirmations.
Specificity
for conventional
venography;
puncture
or 64%
by follow-
for pelvic vein disease was 100% for
MR
imaging,
specificities
were 95% by direct puncture or 98% by follow-up confirmations. In summary, for assessing deep vein thrombosis, MR imaging
is less sensitive
than conventional
veins, equal to conventional
venography
venography
in assessing
in thigh veins, and more sensitive than conventional raphy in assessing disease in the pelvic veins.
in calf
disease venog-
Dr. Sostman also discussed promising trends in the use of MR imaging of pulmonary circulation in the evaluation of pulmonary emboli. In one example, a three-dimensional MR data set from a dog model showed the advantage of the ability to change the plane and angle different parts of the vessels. Possible
in order to examine new techniques en-
compass vascular imaging, thrombus imaging, two-dimensional and three-dimensional techniques, cine MR imaging, breathhold procedures, and black-blood methods.
Three-dimensional Left Ventricular
MR Tagging to Indicate Myocardial Strain
Elias A. Zerhouni
Veigh, C. Moore)
(Baltimore,
MD) and colleagues
used three-dimensional
of
(E. Mc-
(3D) MR tagging
try to resolve a long-standing that is, the inability
Homogeneity
problem in cardiac to measure the deformation
to
physiologyof the heart.
In the study of an object such as the heart, which generates force, one needs to know its mechanical properties and to understand exactly its deformation. Because in traditional
imaging methods,
the heart moves through
the imaging
plane,
the point-to-point vestigate whether
deformation cannot be determined. left ventricular strain is temporally
To inand
spatially
heterogeneous
in the normal heart (as suggested by and implanted bead these researchers “tagged” the heart by labeling little
angiocardiographic,
studies), planes
echocardiographic,
in six directions
entire ventricle
(1 2 segments)
in three dimensions.
and then examined
the
After they had obtained
all the MR images needed, they defined the volume elements in the computer and performed a complete finite strain analysis to study the strain in the radial, longitudinal, and circumferential directions and to therefore obtain a “map” of the
deformation
of the heart in all directions.
A color scale was
MEETING
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894
used for display, in which blue indicated the lowest amount of strain and yellow (red/yellow) the highest amount of strain. By use of this method in 12 normal subjects, an enormous amount of heterogeneity of deformation was seen from the start (no stress, diastole) to strain (systole) of the heart cycle. The strain in the radial direction was very heterogeneous; however, the deformation was homogeneous in the longitudinal or circumferential directions. Moreover, despite the lack of change in total volume of the heart, changes were found in single-volume elements. Therefore, Dr. Zerhouni and colleagues concluded that the heterogeneity seen must be the result of an error introduced in the radial direction in measuring endocardial surface. When the error in the radial direction was corrected
(i.e., when
the volume
was
maintained),
they
found that the normal heart contracted homogeneously. This need for correction in the radial direction in assessing the heterogeneity of heart contraction indicates two things: tremendous uncertainty still exists as to the location of the endocardium
on MR
differently
images,
and the endocandium
may
NEWS
AJR:159,
and sometimes
airways
Dynamic,
and Approaches
uation
with
exhalation,
Ultrafast,
High-Resolution
with bronchiolitis
exhalation
obliterans,
in a patient
new technique to be resolved
by W.
Richard
CT of the Lung
Webb
E. J. Stern,
G. Gamsu).
lution
CT involves
obtaining
(San
Francisco,
Dynamic,
CA;
ultrafast
10 1 00-msec
coau-
high-reso-
high-resolution
CT
scans in 6 sec while the patient performs a forced vital capacity maneuver. The scans are evaluated qualitatively by viewing the scan sequence in the “movie mode, noting the lung-attenuation changes and volume changes during exhal“
ation,
and selecting
for analysis
regions
of interest
to show air trapping. Quantitative evaluation attenuation curves, lung-attenuation values units)
plotted
vs time
for
selected
regions
that appear
includes time(in Hounsfield of interest,
and
changes in lung attenuation from maximum inhalation to maximum exhalation. Dynamic, ultrafast, high-resolution CT scans of the lung were obtained in 1 0 healthy, nonsmoking men with normal spirometry results. The increase in lung-attenuation values from maximum inhalation to maximum exhalation ranged from 84 to 372 H (average, 200 H). Also, with one exception in the normal subjects, the dependent lung showed a greater increase during exhalation than did the nondependent lungthis held true for all areas of the lung and for both prone and supine positions. In patients namic,
with
ultrafast,
obstructive
lung disease,
high-resolution
CT
studies
showed
an
with
dy-
increase
in
lung-attenuation values that averaged only about 50 H from maximum inhalation to maximum exhalation; moreover, in some patients, lung-attenuation values decreased from maximum inhalation to maximum exhalation. This technique detected
air trapping
ary lobule,
in the
bronchial
lung
collapse
that
was
as small
associated
In a patient
and it showed
air trapping
with endobronchial
with
during
metastasis.
This
appears to be very promising, and issues still include explanations for air trapping in normal
subjects and for the decrease exhalation in some patients.
in lung-attenuation
values
on
Thoracocardiography
tions)
thors,
airways.
A. Sackner
(Miami
discussed
Beach,
FL;
coauthons,
K. E.
the use of thonacocardiography
for the noninvasive assessment of ventricular diastolic function and its respiratory variation. If an inductive plethysmographic transducer is placed around the nib cage below on near the ziphoid process, “little lumps” (candiogenic oscilla-
Imaging
A study of a new technique for diagnosing lung diseases characterized by airways obstruction and air trapping was described
and patent
lymphangitic carcinomatosis, dynamic, ultrafast, high-resolution CT showed bronchial occlusion and subsegmental air trapping on exhalation. Dynamic, ultrafast, high-resolution CT showed secondary pulmonary lobular air trapping in patients
Marvin
in Chest
in pa-
move
than does the nest of the heart.
Technologies
and air trapping
tients with normal pulmonary function tests. On dynamic, ultrafast, high-resolution CT, normal lung had homogeneous parenchyma, homogeneous increase in atten-
Bloch, S. Jungoon) New
obstruction
1992
October
as a second-
with air trapping,
are
shown
oscillations,
on the
respiratory
curve;
these
candiogenic
which have been
known about for many years, constitute up to 4% of the total respiratory signal. Candiogenic oscillations increased with inspiration (and decreased with expiration) ifthe transducer band was placed below the nipple line; the reverse was true (oscillations decreased with inspiration and increased with expiration) when the transducer band was placed below the xiphoid. These researchers there-
fore concluded that, by placing the band in different locations, they could judge whether they were measuring the volume of the left on night ventricle. In 1 2 normal subjects, function were obtained
then compared literature.
with the same measures
For example,
on inspiration
several measures of left ventricular by use of thoracocardiognaphy and
and expiration
were compared
as reported
thonacocardiognaphic
stroke
of 1 .0- and
with baseline
stroke
1 .5-I tidal
volumes
in the volumes
volumes
of 0.5 I. At 1.5
I, stroke volume on inspiration was 84% of baseline, stroke volume on expiration was 1 26% of baseline, and average stroke volume was 1 03% of baseline. Also at 1 .5-I tidal
volumes, isovolumic relaxation time on inspiration was 77 msec; on expiration, 82 msec; and on average, 83 msec, all of which were comparable with measurements obtained by Doppler echo studies. Other measurements obtained by thoracocandiography were heart rate, early filling rate/atnial filling
rate, early filling rate/stroke volume, and atnial filling rate/ stroke volume. Moreover, imposed mechanical ventilation showed reversed respiratory amplitudes on thonacocandiography (e.g., with mechanical the left ventricle is greaten
Dr. Sackner
pointed
ventilation, on inspiration
the stroke volume of than on expiration).
out that, if such values can be obtained
accurately by the noninvasive method of thoracocandiognaphy, wedge pressure could be indirectly calculated and,
in
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AJR:159,
MEETING
1992
October
some cases, use of the Swan-Ganz catheter could therefore be avoided. Finally, in 1 0 normal subjects, thoracocardiognaphic results were compared with those from an automatic edge detector echocardiographic device (HP-Somnos 1500). (Dr. Sackner noted that this part of the study took 1 .5 days to perform and 3 months to analyze because of the difficulty of translating HP-Somnos data to analog values.) Stroke volumes found with
the two
methods
were
within
20%
of each
other,
good
agreement was found in both inspiratory and expiratory stroke volumes, the mean difference in isovolumic relaxation time between the two methods was only 2 msec, and the mean difference in peak and atrial filling rates between the two methods was zero. These researchers concluded that thoracocardiography can measure the function of the right on left ventricle both accurately
and
noninvasively.
Furthermore,
they
found
that
their normal values obtained by thoracocardiography for isovolumic relaxation time and early filling rate/atrial filling rate agreed closely with those published in the literature.
NEWS
895
racic Society has provided guidelines for obtaining measures of peak expiratory flow and forced expiratory volume at 1 sec (FEV1), no instructions are given concerning the inspiratory pattern
before
the
forced
expiration.
Course
of Maximal
of Preceding
Flow-Volume
Curves
on Time
Inspiration
A study on maximal expiratory flow-volume maneuvers was by E. D’Angelo(Milan, Italy), E. Prandi (Milan, Italy), and J. Milic-Emili (Montreal, Quebec, Canada) and presented to the society by Dr. Milic-Emili. Although the American Thoperformed
these
re-
vital capacity maneuvers after four different inspiratory maneuvers: 1 , breathe in as fast as possible and then breathe out immediately and as quickly as possible; 2, breathe in as
fast as possible, hold your breath for quickly; 3, breathe in slowly, do not breathe out quickly; and 4, breathe in for 5 sec, then breathe out quickly. In all subjects, the results of the
5 sec, then breathe out hold your breath, then slowly, hold your breath test were similar:
peak
flow and FEV1 were significantly higher with maneuver 1 than with any other inspiratory maneuver and were lowest with
maneuvers both
FEV025
2 and 4. Similar and FEV0.
differences
(forced
and 0.50 sec). Such results Dependence
Therefore,
searchers conducted a study in 13 naive medical students in which volume was measured with body plethysmography and flow was measured at the mouth with a heated Fleisch pneumotachograph. Each subject performed forced expired
could
expiratory
were
also seen in
volumes
be explained
at 0.25
by a simple
viscoelastic model of the respiratory system that was introduced 50 years ago. The data provided by this study indicate that standardization of the forced vital capacity maneuver must take into account the pattern of the preceding inspiration. With such standardization, the measurements will be more reproducible and comparable than they are currently.
