Accuracy of Ultrasound in Diagnosing Abdominal Robert
Richardson, MD; Lawrence
W.
Norton, MD; John Eule, MD;
B-mode ultrasonography was performed in 246 patients with suspected abdominal masses over a seven-year period. In 105 (43%), the accuracy of ultrasonic diagnosis was evaluated surgically. Sonography was proven correct in 60 (57%) patients who had undergone operation. Among 141 patients who had not undergone operation and whose diagnoses were established by other means, ultrasonography agreed with the clinical diagnosis in 69 (31%). Ultrasound accuracy, as confirmed by operation, was highest for splenic masses (100%) and for aortic aneurysm (88%). Liver masses were correctly identified in 56% of patients and gallbladder lesions in 38%. While only a 48% accuracy was obtained in diagnosing pancreatic disease, 64% of all pseudocysts were localized. Ultrasonography correlated positively with operative findings in 56% of renal masses. Intraperitoneal abscess was accurately diagnosed in 61% of patients but retroperitoneal adenopathy in only 33%. Abdominal ultrasonography, while accurately diagnosing splenic and aortic masses, failed to identify approximately half of other mass lesions. Improved techniques hold promise of improving this diagnostic accuracy.
simple, available, and rela¬ of diagnosing abdominal mass lesions. This noninvasive technique has proved help¬ ful in detecting obscure masses that cannot be defined by routine roentgenography.1 Previously reported experience with abdominal sonography suggests that certain masses, such as abdominal aortic aneurysm, can be diagnosed easily,2 while others, such as intraperitoneal abscess, are less frequently de¬ tected.2 While much attention has been given to sonographic technique and application, less emphasis has been
scanning Ultrasound tively inexpensive
Accepted
is
a
means
for publication March 14, 1975. From the Department of Surgery, Denver General Hospital and the University of Colorado School of Medicine, Denver. Read before the 32nd annual meeting of the Central Surgical Association, Chicago, Feb 28, 1975. Reprint requests to Department of Surgery, Denver General Hospital, Denver, CO 80204 (Dr. Norton).
Ben
Masses Eiseman, MD
placed
nosis. This
on
determining the
accuracy of ultrasound
diag¬
study reviews our experience with ultrasound scanning for identification of abdominal masses in nonobstetric patients. It assesses the accuracy of ultrasound diagnosis in patients with and without subsequent oper¬ ative confirmation.
METHODS
During the seven years, 1967 to 1974, B-scan ultrasound was used to diagnose abdominal mass lesions in 246 patients at the Denver General Hospital. Ages ranged from 1 day to 85 years, with a mean of 49 years. Males (63%) outnumbered females (37%). Only four examinations were performed in the first year of the study compared to 101 in the seventh year (Fig 1). The frequency of ultrasonic study of abdominal masses increased sharply during the fifth year (1971) when information regarding the technique became widely disseminated among surgical staff and a radiol¬ ogist devoted his efforts exclusively to sonography. The exact nature of the abdominal mass studied ultrasonically was established by subsequent laparotomy in 105 (43%) patients (Fig 2). Among these patients who underwent operation, nine had masses in the liver, eight in the gallbladder, five in the spleen, and 23 in the pancreas. Sixteen had renal masses and eight had ab¬ dominal aortic aneurysm. Other intraperitoneal mass lesions, in¬ cluding abscess (23), were found in 33 patients and retroperitoneal masses were discovered in three (Table 1). The 141 patients who did not undergo operation were studied ul¬ trasonically for known or suspected abdominal masses. In two thirds of them, the nature and site of the mass was indicated by physical examination, routine roentgenography, angiography, or endoscopy. In the others, the identity of the mass was more ob¬ scure, although a clinical diagnosis was made (Table 1). Fiftyfour patients who did not undergo operation were thought to have masses of the liver (11), gallbladder (three), or pancreas (40). Re¬ nal lesions were suspected in 37 and aortic aneurysm in 18. In¬ traperitoneal masses, including abscesses, were diagnosed clini¬ cally in 31 and a retroperitoneal mass in one patient. The accuracy of ultrasound diagnosis was determined by com¬ paring sonographic findings of the nature and site of an abdomi¬ nal mass to tissue diagnosis obtained at operation or to the clinical impression in patients who had not undergone operation. Com-
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parison was made by a physician reviewer who had no prior knowledge of patients or sonographic technique. Sonograms were not reexamined for purposes of revising diagnosis but were re¬ viewed for possible explanation of false-positive or false-negative interpretation. Operations confirming ultrasound diagnosis were performed be¬ tween one and 31 days (mean, eight days) after examination. Fol¬ low-up of patients who did not undergo operation ranged from two weeks to 49 months (mean, 7.7 months). The final clinical im¬ pression of the nature of the abdominal mass in such patients was used for comparison to sonographic diagnosis. No substantial change in scanning technique occurred during the study period. Interpretation of sonograms prior to the fourth year (1971) involved four radiographers, while only one (J.E.) was responsible for diagnosis thereafter. RESULTS In 60 (57%) of 105 patients who underwent operation, ul¬ trasound diagnosis of an abdominal mass was shown to be correct (Table 2). Among 141 patients who did not un¬ dergo operation, ultrasound findings agreed with the clini¬ cal diagnosis in 69 (49%) (Table 3). Liver
The accuracy of sonography in diagnosing a liver mass in patients who were later operated on is tabulated in Table 4. Among nine such patients, overall accuracy was 56%. Five of seven patients (71%) shown to have liver mé¬ tastases at laparotomy were correctly diagnosed preoper¬ atively by ultrasound. Two other patients with either liver abscess or cyst were not diagnosed. Among 11 patients who did not undergo operation and who were thought to have a liver mass, ultrasound corre¬ lated positively with clinical diagnosis in only four (36%). One patient had a palpable liver mass, thought to be hepatoma, which was not shown sonographically. Four had clinical evidence of hepatic abscess, but in only one did ul¬ trasound suggest this diagnosis. Liver métastases were identified by technetium Tc 99m scan in four patients, two of whom were also diagnosed by ultrasound. In two oth¬ ers, a clinical impression of hepatomegaly (Riedel lobe) was
not
supported by sonography.
Gallbladder In three of eight (38%) patients who underwent oper¬ ation, ultrasound had diagnosed lesions of the gallbladder. Three of four patients with gallbladder distention were so diagnosed prior to operation (Table 4). In four others, the presence of gallstones, measuring 1.5 cm in diameter or was missed. Distention of the gallbladder was not found by ul¬ trasound in two of three patients who were not operated on and who had enlarged gallbladders as shown by cho-
more,
lecystography.
Spleen
patients surgically proven splenomegaly diagnosed correctly by B-scanning (Table 4). A subcapsular hematoma of the spleen was identified in another patient prior to splenectomy. Actual splenic rupture was All three
were
with
diagnosed in a patient whose sonogram is reproduced in Fig 3. Sound echos were detected in the midst of the nor¬ mally sonolucent spleen area giving evidence of hema¬ toma dividing splenic pulp. There were no patients who did not undergo operation who had a suspected spleen mass. Pancreas
Twenty-three patients had operative evaluation of a son¬ ographic diagnosis made in regard to pancreatic disease. A correct diagnosis was made in 11 (48%). Only nine (64%) of 16 suspected pseudocyst patients were accurately diag¬ nosed by ultrasound (Table 4). In three of the five misses, a false-positive diagnosis was made, and in two a falsenegative interpretation was given. Figure 4 shows an ex¬ ample of the latter. The sonolucent area in the head of the pancreas actually proved to be a pseudocyst at operation. Six patients who underwent operation had carcinoma of the pancreas proved by biopsy examination. In two, prior sonography revealed a solid pancreatic tumor. One patient had pancreatitis with marked peripancreatic inflamma¬ tion creating a palpable abdominal mass that was not de¬ tected by ultrasound before operation. Two other patients, diagnosed as having pancreatitis by ultrasound, had a normal pancreas at exploration. A clinical diagnosis of pancreatic mass was supported by sonography in 13 (33%) of 40 patients who did not un¬ dergo operation (Table 3). Pseudocyst was suspected in 25, of whom eight (32%) had sonograms making this diag¬ nosis. Six additional patients were thought to have carci¬
noma of the pancreas. Ultrasound showed a solid mass in two. Of nine patients with pancreatitis and a palpable mass who did not undergo operation, three were similarly
diagnosed by
ultrasound.
Kidney Masses within the kidney were identified by operation in 16 patients. Sonography diagnosed the lesion preopera¬ tively in nine (56%). Two of five patients with renal carci¬ noma were so diagnosed (Table 4). In each of four cases of solitary cyst, ultrasound scanning detected the lesion. Re¬ nal calculi were diagnosed in two of three patients but perinephric abscess was missed in two others. One of two patients with multiple renal cysts who had undergone op¬ eration was diagnosed sonographically. Thirty-seven patients had evidence of a renal mass on the basis of pyelography or angiography. In 26 (70%) ul¬ trasound diagnosis correlated positively with these find¬ ings. A solitary cyst was shown roentgenographically in 18 patients, seven of whom had supporting sonograms. Seven others had a clinical diagnosis of solid renal tumor that could be seen sonographically in three. Polycystic kid¬ ney was suspected in five with 60% ultrasound correlation. Hematoma was the clinical diagnosis in three patients, one of whom had a confirmatory sonogram. Aorta
Of 26 patients examined ultrasonically for possible abdominal aortic aneurysm, eight were operated on subse-
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quently. Seven (88%) of these had been diagnosed as hav¬ ing an aneurysm by ultrasound (Table 4). In one success¬ fully diagnosed patient, aneurysm was not shown by aortography but was obvious on the sonogram (Fig 5). By increasing gain of the B-scanner, clot lining the aneu¬ rysm, which had led to mini-interpretation of the aortogram, was identified. The single patient who underwent operation in whom the diagnosis of aneurysm was missed had a technically unsatisfactory examination. Only seven (39%) of the 18 operated patients thought to have abdominal aortic aneurysm who did not undergo op¬ eration had sonograms suggesting this diagnosis. These patients have been observed by periodic ultrasound exam¬ ination for evidence of increasing aneurysm size. No pa¬ tient clinically diagnosed as having aortic aneurysm who had a normal sonogram has developed an expanding aortic mass.
Fig 1 .—Frequency of ultrasonic diagnosis of abdominal masses increased markedly during fifth year (1971) of study. Half-year figures for 1974 are not shown.
Fig 2.—Ultrasound diapnosis (DX) of abdominal mass was eval¬ operatively in 43% of patients. In remainder, sonography was compared to nonopeiative clinical diagnosis. uated
Intraperitoneal
Thirty-three patients, studied preoperatively by ul¬ trasound, were found at laparotomy to have intraperito¬ neal masses in areas not previously described. Nineteen (58%) were diagnosed correctly by ultrasound. A total of 23 patients who underwent operation were found to have one or more intraperitoneal abscesses measuring at least 3 cm in diameter. In 14 (61%) the size and location of the ab¬ scess was accurately predicted by sonography (Table 4). The success of ultrasound in localizing intraperitoneal pus is tabulated in Table 5. Subphrenic abscess was identified in six (75%) of eight patients. Subhepatic abscess was found in two of four patients and appendiceal abscess in three of four. Abscesses of the lesser sac and the right paracolic area were missed in separate patients. Intraperitoneal masses in other patients who had un¬ dergone operation included ovarian cyst (two), uterine myoma (one), colon carcinoma (two), mesenterie cyst (one), urinary bladder carcinoma (one), hematoma (two), and metastatic cervix carcinoma (one) (Table 4). A preop¬ erative sonographic diagnosis identified the mass in five (50%) of ten patients. Twenty-one patients had a clinical diagnosis of intra¬ peritoneal abscess but did not undergo laparotomy.
Table 2.—Ultrasound Accuracy in Patients Who Underwent Operation*
Table 1,—Site of Abdominal Masses* Site Liver Gallbladder
Correct
Patients
Patients Not
Operated On
Operated On
Total
9 8
11 3
20 11
23 16 8 33
40 37 18 31
63 53 26 64
Site of Mass Liver Gallbladder
Spleen Pancreas
Kidney Aorta
Intraperitoneal Retroperitoneal
Spleen
Site confirmed in 105 patients who were operated pected in 141 patients who were not operated on. *
Pancreas
Kidney Aorta
Intraperitoneal·
Diagnosis 5 (56%) 3 (38%) 5 (100%) 11 (48%) 9 (56%) 7 (88%)
Patients 9 8 5 23 16 8 33
on
and
sus¬
Ultrasonic diagnosis of abdominal patients who underwent operation. *
correct in
_
mass
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(58%) (33%) 60 (57%) of
19 1
Retroperitoneal_3
Twelve (57%) of these patients had ultrasonic evidence of abscess. Among ten other patients with suspected in¬ traperitoneal lesions who did not undergo operation, six (60%) had sonograms that agreed with the clinical diag¬ nosis. Positive correlation of ultrasound with the clinical diagnosis in a total of 31 patients with intraperitoneal mass who did not undergo operation was 58% (Table 3).
Table 3.—Ultrasound Accuracy in Patients Who Did Not Undergo Operation* Correct
Site of Mass Liver Gallbladder
Kidney
Para-aortic adenopathy constituting a palpable abdomi¬ nal mass was discovered surgically in three patients. One had been diagnosed by preoperative ultrasound scan
False-Positive
40 37
13 26 7
31
18 0
Aorta
Intraperitoneal Retroperitoneal
Ultrasonic diagnosis agreed with clinical diagnosis patients who did not undergo operation.
vs
False-Negative
Table
The nature of ultrasonic misdiagnosis is analyzed in Table 6. Among 45 patients who underwent operation, 25 (56%) had a false-positive diagnosis and 20 (44%) had a false-negative interpretation of sonograms. False-posi¬ tive diagnoses were more common with renal masses and intraperitoneal abscess. A false-negative impression was responsible for four of five missed gallbladder diagnoses.
Patients
Liver Metastatic carcinoma
Abscess
Cyst Gallbladder Distention
During the seven years of this study, B-scan ultrason¬ ography was introduced and popularized as a means of diagnosing abdominal masses. Errors of interpretation during early experience were due to limited training, lack of diagnostic criteria, and variability of equipment. Such factors no longer pertain, but it is obvious that ultrasound is still of limited value in defining the nature of many ab¬
Spleen Splenomegaly
sources
of error in
diagnosing aortic an¬
eurysm are (1) enlarged periaortic lymph nodes that can¬ not be acoustically separated from aorta and (2) excessive
(49%)
Operation* Diagnosis 5 0 0
(71%)
3 0
(75%)
Rupture Pancreas
Pseudocyst Carcinoma Pancreatitis
14 6 3
9 2 0
(64%) (33%)
2 4 2 1 0
(40%) (100%) (67%) (50%)
7
(88%)
Kidney Carcinoma
techniques.
in 69
3 (100%) 1 (100%) 1 (100%)
Hematoma
masses.
Other potential
(33%) (70%) (39%) (58%)
Correct Mass
Stones
Surprisingly few studies have evaluated the accuracy of ultrasound diagnosis of nonobstetric abdominal masses since the initial report of the technique by Howry and Bliss in 1952.4 Limitations of sonography were described by Holm1 in his review of patients with lesions in the up¬ per part of the abdomen. While solid or cystic masses mea¬ suring at least 2 to 3 cm in diameter were readily de¬ tected, smaller lesions or those covered by gas-filled intestine were not. Recently, attention has been drawn to the accuracy of ultrasound in detecting abdominal aortic aneurysm.2 The elastic walls of the aorta constitute a distinct acoustic density making the structure easy to identify. Aneurysms can be measured with an accuracy of ± 3 mm and echoes from thrombi within the vessel often can be demonstrated. Our experience confirms that ultrasonography is an ideal means of diagnosing and following up abdominal aortic aneurysm. The only false-negative result was due to bowel gas, which prevented adequate sound penetration of the aneurysm. To a great extent, this error can be obviated by
(33%)
4.—Accuracy of Ultrasound in Diagnosing Abdominal Mass in Patients Who Underwent
COMMENT
newer
1
*
single patient who had not undergone operation was presumed to have retroperitoneal adenopathy but this was not confirmed sonographically.
dominal
11
0
Pancreas
A
Diagnosis 4 (36%:
Spleen
Retroperitoneal
(Table 4).
Patients
Single cyst Stones
Multiple cysts
Abscess Aorta
Aneurysm
Intraperitoneal Abscess
Ovary-uterus Colon Other
23 3 2 5
14 (61%) 2 (67%) 1 2
(50%) (40%)
1
(33%:
Retroperitoneal Nodes
*
Among patients who underwent operation, accuracy of ultrasonog¬ raphy was highest for splenic masses and aortic aneurysm and lowest for gallstones.
gain settings on B-scan equipment that obscure the aneu¬ rysm, since intraluminal thrombus produces echoes at high gain. The ability of ultrasound to define the nature of splenic masses in all patients studied was an unexpected finding of this study. The high posterior position of the spleen should make it less acoustically accessible than other ab¬ dominal organs. Scanning is done between the ribs so that
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Fig 3.—Line of echoes patient (arrow). Diagnosis
laparotomy.
within sonolucent of splenic rupture
spleen was
of trauma confirmed by
bone echo artifacts do not produce false-positive echoes within the spleen. Small splenic lesions shadowed by the ribs might be obscured altogether. Gas in either the splenic flexure of the colon or the fundus of the stomach might also prevent adequate sound penetration for vis¬ ualization of the spleen. The diagnostic detail seen in two patients with splenic trauma suggests that sonography be used routinely to evaluate trauma patients suspected of having delayed rupture of the spleen. The repeatable, noninvasive nature of the technique has special application in such patients. The usefulness of ultrasound for diagnosis of hepatic masses is considerably less than for aortic and splenic masses. With present equipment, the diameter of solid le¬ sion, such as liver métastases, must exceed 3 to 4 cm be¬ fore the mass can be identified. Such extensive metastatic disease was present in our patients with abnormal scans. Métastases may appear (1) as patches of echoes within the sonolucent liver, (2) as sonolucent areas when the liver is scanned at high gain settings, or (3) as doughnut-like echoes with an outer ring of acoustical density and an in¬ ner sonolucent area. At present, ultrasound cannot con¬ tribute decisively to the differential diagnosis between cirrhosis and métastases.1 We were disappointed that sonography failed to detect fluid-filled spaces in the livers of two patients. Subsequent
Table 5.—Ultrasound
Accuracy In Localizing Intraperitoneal Abscess* Correct
Abscess Site
Patients
Subphrenic, right Subphrenic, left Subhepatic Lesser
Fig 4.—Sonolucent area (arrow), in head of pancreas, which, contrary to ultrasound diagnosis, proved to be small pseudocyst.
3 5 4 1 4
sac
Appendiceal Paracolic Pelvic *
0 3 2
4 1
Abdominal wall
Overall accuracy of ultrasound in 61%.
Diagnosis 2 (67%) 4 (80%) 2 (50%)
1
(75%) (50%) (100%)
localizing intraperitoneal ab¬
scess was
in
Fig 5.—Sonolucent space (arrow) representing aortic aneurysm patient
whose
aortogram showed
no
Table 6.—Nature of Ultrasonic Misdiagnosis in Patients Who Underwent Operation*
aneurysm.
Site of Mass Liver (4) Gallbladder (5)
False-Positive
False-Negative
3
1
Spleen (0) Pancreas (12)
Kidney (7) Aorta (1)
Intraperitoneal (14) Retroperitoneal (2)
10
Of 45 patients who underwent operation and who were misdiagnosed by ultrasound, 25 (56%) had false-positive and 20 (44%) had *
false-negative interpretations.
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that intrahepatic abscesses of less than 3 cm diameter will be missed in half of the patients studied by B-mode scanning. As confirmed in this study, ultrasound appears to have no advantage over roentgen cholecystography in detect¬ ing gallstones.5 Respiratory motion can obscure echoes from gallstones. Furthermore, a stone must be of suffi¬ cient size (0.5 to 1.0 cm) and have adequate acoustic differ¬ ence from bile to produce detectable echoes. Reverber¬ ation artifacts from ribs and the anterior body wall can produce echoes within the gallbladder that might be mis¬ taken for gallstones. Ultrasound may be of value, how¬ ever, in cases of roentgenographic nonvisualization of the gallbladder or in patients who cannot tolerate cholecystog¬ raphy.6 Since sonography does identify gallbladder dis¬ tention with reasonable accuracy, it may prove to be of some use in patients with obstructive jaundice. Also disappointing was the low rate of accuracy of ul¬ trasound in diagnosing pancreatic disease. Other reported experience suggests that pseudocysts might be detected with accuracy approaching 90%.79 Instead, only two thirds of our pseudocyst patients were correctly diagnosed. False-positive errors were reduced in more recent experi¬ ence by recognizing the echo pattern of massive edema surrounding the inflamed pancreas. Occasional false-posi¬ tive or false-negative interpretations are apt to continue since differentiating between small pseudocysts in the head of the pancreas and edema of that portion of the gland may not be possible with B-mode equipment. There is no doubt that ultrasound is of great help in fol¬ lowing up the development of pancreatic pseudocyst once a sonolucent mass has appeared.10 Our results suggest that B-mode scanning has appli¬ cation in the diagnosis of both solid and cystic renal
experience suggests
Whether it has advantage over established tech¬ as pyelography and angiography has not been such niques shown. While admittedly not a screening technique, ultra¬ sonography might have application in the treatment of cystic renal lesions. A mass detected by pyelography, shown to be cystic by sonography, could be aspirated with¬ out the need for prior angiography. Holm et al11 have pre¬ viously described the use of ultrasound in localizing perinephric abscesses and other masses. Ultrasound provides one means of finding localized pus in the abdomen. Initial reports of its use for this purpose were encouraging.2 Successful diagnosis occurred in 61% of our patients. Intraperitoneal abscesses and hematomas can be identified by the presence of echo-free areas that disturb the normal shape or position of organs. Air-filled intestine overlying the abscess might reflect sound, pre¬ venting diagnosis. Another problem in patients with ab¬ scess is the frequency with which multiple incisions and wound appliances prevent adequate abdominal scanning. It is unlikely that intraperitoneal abscesses measuring less than 2 to 3 cm in diameter will be detected with accuracy by current ultrasonic techniques. Retroperitoneal masses have only a limited chance of being detected by ultrasound. A retroaortic mass dis¬ placing the abdominal aorta from the lumbar vertebrae can be found with greater accuracy.12 New developments in ultrasound technology hold prom¬ ise of improving sonographic diagnosis of abdominal masses. One such advance is the use of gray scale ultra¬ sonography by which lesions as small as 1 cm may be dis¬ covered in previously obscure areas such as liver. It is likely, therefore, that ultrasound will retain a place among various diagnostic techniques to identify and localize the obscure abdominal mass. masses.
References 1. Holm HH: Ultrasonic scanning in the diagnosis of space-occupying lesions of the upper abdomen. Br J Radiol 44:24-36, 1971. 2. Leopold GR, Goldberger LE, Bernstein EF: Ultrasonic detection and evaluation of abdominal aortic aneurysms. Surgery 72:939-945, 1972. 3. Jensen F, Pedersen JF: The value of ultrasonic scanning in the diagnosis of intra-abdominal abscesses and hematomas. Surg Gynecol Obstet 139:326-328, 1974. 4. Howry DH, Bliss WR: Ultrasonic visualization of soft tissue structures of the body. J Lab Clin Med 40:579-592, 1952. 5. Doust BD, Maklad NF: Ultrasonic B-mode examination of the gallbladder: Technique and criteria for the diagnosis of gallstones. Radiology
110:643-647. 1974. 6. Goldberg BB, Harris K, Broocker W: Ultrasonic and radiographic cholecystography. Radiology 111:405-409, 1974. 7. Bradley EL, Clements JL: Implications of diagnostic ultrasound in the
of pancreatic pseudocysts. Am J Surg 127:163-173, 1974. 8. Stuber JL, Templeton AW, Bishop K: Sonographic diagnosis of pancreatic lesions. Am J Roentgenol Radium Ther Nucl Med 116:406-412,1972. 9. Filly RA, Freimanis AK: Echographic diagnosis of pancreatic lesions, ultrasound scanning techniques and diagnostic findings. Radiology 96:575\x=req-\ 582, 1970. 10. Bradley EL, Clements LJ: Spontaneous resolution of pancreatic pseudocysts: Implications for timing of operative intervention. Am J Surg 129:23-28, 1975. 11. Holm HH, Kristensen JK, Rasmussen SN, et al: Ultrasonic diagnosis of juxtarenal masses. Scand J Urol Nephrol 15(suppl 6): 83-88, 1972. 12. Spirt BA, Skolnick ML, Carsky EW, et al: Anterior displacement of the abdominal aorta: A radiographic and sonographic study. Radiology 111:399-403, 1974.
surgical management
Discussion Roger F. Smith, Md, Detroit: I am in agreement that ul¬ trasound examination is becoming an increasingly important ad¬ junct in the differential diagnosis of abdominal masses. Our chief experience at the Henry Ford Hospital with echography has been in patients with abdominal aortic aneurysms, where it appears to have some definite limitations. Fortunately, most abdominal aneurysms can be diagnosed by
physical examination or by an anteroposterior and lateral roentgenograms for aortic calcification. When the problem of the diagnosis of a pulsatile mass cannot be resolved by these simpler means, we prefer to go directly to a translumbar aortogram as the definitive study. We have found in the case of an abdominal aortic aneurysm that the added information obtained by this method as to the state of the vesical, pelvic, and distal circulation is of great careful
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benefit to us in planning a proper operation. In contrast, however, if a nonpulsatile midabdominal mass is felt, then an echogram is our first choice as the least noninvasive form of examination to rule out an abdominal aneurysm and to determine if the lesion is solid or cystic. One serious limitation that we have observed in the diagnostic use of ultrasound has been in its inability to accurately differ¬ entiate between a retroperitoneal lymphoma and an abdominal aneurysm. This has not been a rare clinical problem in our concen¬ trated vascular practice. It is our opinion that ultrasound, at its present level of perfec¬ tion, must assume a secondary role to aortography in the differ¬ ential diagnosis and management of abdominal aneurysms. Alexander J. Walt, MD, Detroit: We have used a fair amount of ultrasound in one of our affiliated hospitals, and recently had the radiologist who does it there give us an update. I think one has to look at the state of the art, and if it is possible to make some predictions, I would suggest (as others have) that ten years from now ultrasound will have replaced possibly 40% to 50% of what we currently are doing in our radiological departments. If one looks at this in the light of roentgenograms where roent¬ genograms were in the year 1910—and see the distance roentgen¬ ography has come since then, I suspect we are looking at ul¬ trasound in terms of a similar infancy. With the new gray scale types of techniques, the experts are able to show all sorts of de¬ tails. We even had stones in the common duct beautifully shown to us, and lesions in the aorta, the takeoff of the superior mesenterie artery, and even the inferior mesenterie. We, too, have had some disappointments in trying to delineate pseudocysts of the pan-
creas, but it may well be that we ask too much of the technique at present. I am not sure whether Dr. Norton is disappointed with
or pleased with them. We have, on occasion, had some great triumphs where ultrasound has helped our surgery. Dr. Norton, have you analyzed your cases in terms of the value
his results
of sonography to you in the years 1967 to 1972 and the years from 1972 until now? I suspect your radiologists are much more helpful to you today than they were then. I enjoyed the paper, and wish to reiterate that I believe that within five years sonography will be a very common and invalu¬ able investigation in the delineation of abdominal surgical condi¬ tions. Dr. Norton: Dr. Smith's much wider experience with aneurysm confirms our general position that ultrasound is currently of sec¬ ondary importance in diagnosing abdominal masses, although for aortic disease it is probably more accurate than for other organs. In answer to Dr. Walt's question, we agree entirely that the success of diagnosis has been improving, and in recent years with experience our ultrasonographer, I think, is more accurate. There is no question that gray scale scanning should improve our ability to pick up smaller lesions. We are talking about detection in the area of 0.5 to 1.0 cm vs our current B-mode accuracy of about 3 to 4 cm. That is hopeful. We were disappointed in our accuracy of detecting pseudocysts. Sixty-four percent, we thought, was disappointing in view of ar¬ ticles that had suggested an accuracy as high as 90%. Compared to reports published previously, we were disappointed, but perhaps we are asking too much.
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Richardson, MD; Lawrence
W.
Norton, MD; John Eule, MD;
B-mode ultrasonography was performed in 246 patients with suspected abdominal masses over a seven-year period. In 105 (43%), the accuracy of ultrasonic diagnosis was evaluated surgically. Sonography was proven correct in 60 (57%) patients who had undergone operation. Among 141 patients who had not undergone operation and whose diagnoses were established by other means, ultrasonography agreed with the clinical diagnosis in 69 (31%). Ultrasound accuracy, as confirmed by operation, was highest for splenic masses (100%) and for aortic aneurysm (88%). Liver masses were correctly identified in 56% of patients and gallbladder lesions in 38%. While only a 48% accuracy was obtained in diagnosing pancreatic disease, 64% of all pseudocysts were localized. Ultrasonography correlated positively with operative findings in 56% of renal masses. Intraperitoneal abscess was accurately diagnosed in 61% of patients but retroperitoneal adenopathy in only 33%. Abdominal ultrasonography, while accurately diagnosing splenic and aortic masses, failed to identify approximately half of other mass lesions. Improved techniques hold promise of improving this diagnostic accuracy.
simple, available, and rela¬ of diagnosing abdominal mass lesions. This noninvasive technique has proved help¬ ful in detecting obscure masses that cannot be defined by routine roentgenography.1 Previously reported experience with abdominal sonography suggests that certain masses, such as abdominal aortic aneurysm, can be diagnosed easily,2 while others, such as intraperitoneal abscess, are less frequently de¬ tected.2 While much attention has been given to sonographic technique and application, less emphasis has been
scanning Ultrasound tively inexpensive
Accepted
is
a
means
for publication March 14, 1975. From the Department of Surgery, Denver General Hospital and the University of Colorado School of Medicine, Denver. Read before the 32nd annual meeting of the Central Surgical Association, Chicago, Feb 28, 1975. Reprint requests to Department of Surgery, Denver General Hospital, Denver, CO 80204 (Dr. Norton).
Ben
Masses Eiseman, MD
placed
nosis. This
on
determining the
accuracy of ultrasound
diag¬
study reviews our experience with ultrasound scanning for identification of abdominal masses in nonobstetric patients. It assesses the accuracy of ultrasound diagnosis in patients with and without subsequent oper¬ ative confirmation.
METHODS
During the seven years, 1967 to 1974, B-scan ultrasound was used to diagnose abdominal mass lesions in 246 patients at the Denver General Hospital. Ages ranged from 1 day to 85 years, with a mean of 49 years. Males (63%) outnumbered females (37%). Only four examinations were performed in the first year of the study compared to 101 in the seventh year (Fig 1). The frequency of ultrasonic study of abdominal masses increased sharply during the fifth year (1971) when information regarding the technique became widely disseminated among surgical staff and a radiol¬ ogist devoted his efforts exclusively to sonography. The exact nature of the abdominal mass studied ultrasonically was established by subsequent laparotomy in 105 (43%) patients (Fig 2). Among these patients who underwent operation, nine had masses in the liver, eight in the gallbladder, five in the spleen, and 23 in the pancreas. Sixteen had renal masses and eight had ab¬ dominal aortic aneurysm. Other intraperitoneal mass lesions, in¬ cluding abscess (23), were found in 33 patients and retroperitoneal masses were discovered in three (Table 1). The 141 patients who did not undergo operation were studied ul¬ trasonically for known or suspected abdominal masses. In two thirds of them, the nature and site of the mass was indicated by physical examination, routine roentgenography, angiography, or endoscopy. In the others, the identity of the mass was more ob¬ scure, although a clinical diagnosis was made (Table 1). Fiftyfour patients who did not undergo operation were thought to have masses of the liver (11), gallbladder (three), or pancreas (40). Re¬ nal lesions were suspected in 37 and aortic aneurysm in 18. In¬ traperitoneal masses, including abscesses, were diagnosed clini¬ cally in 31 and a retroperitoneal mass in one patient. The accuracy of ultrasound diagnosis was determined by com¬ paring sonographic findings of the nature and site of an abdomi¬ nal mass to tissue diagnosis obtained at operation or to the clinical impression in patients who had not undergone operation. Com-
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parison was made by a physician reviewer who had no prior knowledge of patients or sonographic technique. Sonograms were not reexamined for purposes of revising diagnosis but were re¬ viewed for possible explanation of false-positive or false-negative interpretation. Operations confirming ultrasound diagnosis were performed be¬ tween one and 31 days (mean, eight days) after examination. Fol¬ low-up of patients who did not undergo operation ranged from two weeks to 49 months (mean, 7.7 months). The final clinical im¬ pression of the nature of the abdominal mass in such patients was used for comparison to sonographic diagnosis. No substantial change in scanning technique occurred during the study period. Interpretation of sonograms prior to the fourth year (1971) involved four radiographers, while only one (J.E.) was responsible for diagnosis thereafter. RESULTS In 60 (57%) of 105 patients who underwent operation, ul¬ trasound diagnosis of an abdominal mass was shown to be correct (Table 2). Among 141 patients who did not un¬ dergo operation, ultrasound findings agreed with the clini¬ cal diagnosis in 69 (49%) (Table 3). Liver
The accuracy of sonography in diagnosing a liver mass in patients who were later operated on is tabulated in Table 4. Among nine such patients, overall accuracy was 56%. Five of seven patients (71%) shown to have liver mé¬ tastases at laparotomy were correctly diagnosed preoper¬ atively by ultrasound. Two other patients with either liver abscess or cyst were not diagnosed. Among 11 patients who did not undergo operation and who were thought to have a liver mass, ultrasound corre¬ lated positively with clinical diagnosis in only four (36%). One patient had a palpable liver mass, thought to be hepatoma, which was not shown sonographically. Four had clinical evidence of hepatic abscess, but in only one did ul¬ trasound suggest this diagnosis. Liver métastases were identified by technetium Tc 99m scan in four patients, two of whom were also diagnosed by ultrasound. In two oth¬ ers, a clinical impression of hepatomegaly (Riedel lobe) was
not
supported by sonography.
Gallbladder In three of eight (38%) patients who underwent oper¬ ation, ultrasound had diagnosed lesions of the gallbladder. Three of four patients with gallbladder distention were so diagnosed prior to operation (Table 4). In four others, the presence of gallstones, measuring 1.5 cm in diameter or was missed. Distention of the gallbladder was not found by ul¬ trasound in two of three patients who were not operated on and who had enlarged gallbladders as shown by cho-
more,
lecystography.
Spleen
patients surgically proven splenomegaly diagnosed correctly by B-scanning (Table 4). A subcapsular hematoma of the spleen was identified in another patient prior to splenectomy. Actual splenic rupture was All three
were
with
diagnosed in a patient whose sonogram is reproduced in Fig 3. Sound echos were detected in the midst of the nor¬ mally sonolucent spleen area giving evidence of hema¬ toma dividing splenic pulp. There were no patients who did not undergo operation who had a suspected spleen mass. Pancreas
Twenty-three patients had operative evaluation of a son¬ ographic diagnosis made in regard to pancreatic disease. A correct diagnosis was made in 11 (48%). Only nine (64%) of 16 suspected pseudocyst patients were accurately diag¬ nosed by ultrasound (Table 4). In three of the five misses, a false-positive diagnosis was made, and in two a falsenegative interpretation was given. Figure 4 shows an ex¬ ample of the latter. The sonolucent area in the head of the pancreas actually proved to be a pseudocyst at operation. Six patients who underwent operation had carcinoma of the pancreas proved by biopsy examination. In two, prior sonography revealed a solid pancreatic tumor. One patient had pancreatitis with marked peripancreatic inflamma¬ tion creating a palpable abdominal mass that was not de¬ tected by ultrasound before operation. Two other patients, diagnosed as having pancreatitis by ultrasound, had a normal pancreas at exploration. A clinical diagnosis of pancreatic mass was supported by sonography in 13 (33%) of 40 patients who did not un¬ dergo operation (Table 3). Pseudocyst was suspected in 25, of whom eight (32%) had sonograms making this diag¬ nosis. Six additional patients were thought to have carci¬
noma of the pancreas. Ultrasound showed a solid mass in two. Of nine patients with pancreatitis and a palpable mass who did not undergo operation, three were similarly
diagnosed by
ultrasound.
Kidney Masses within the kidney were identified by operation in 16 patients. Sonography diagnosed the lesion preopera¬ tively in nine (56%). Two of five patients with renal carci¬ noma were so diagnosed (Table 4). In each of four cases of solitary cyst, ultrasound scanning detected the lesion. Re¬ nal calculi were diagnosed in two of three patients but perinephric abscess was missed in two others. One of two patients with multiple renal cysts who had undergone op¬ eration was diagnosed sonographically. Thirty-seven patients had evidence of a renal mass on the basis of pyelography or angiography. In 26 (70%) ul¬ trasound diagnosis correlated positively with these find¬ ings. A solitary cyst was shown roentgenographically in 18 patients, seven of whom had supporting sonograms. Seven others had a clinical diagnosis of solid renal tumor that could be seen sonographically in three. Polycystic kid¬ ney was suspected in five with 60% ultrasound correlation. Hematoma was the clinical diagnosis in three patients, one of whom had a confirmatory sonogram. Aorta
Of 26 patients examined ultrasonically for possible abdominal aortic aneurysm, eight were operated on subse-
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quently. Seven (88%) of these had been diagnosed as hav¬ ing an aneurysm by ultrasound (Table 4). In one success¬ fully diagnosed patient, aneurysm was not shown by aortography but was obvious on the sonogram (Fig 5). By increasing gain of the B-scanner, clot lining the aneu¬ rysm, which had led to mini-interpretation of the aortogram, was identified. The single patient who underwent operation in whom the diagnosis of aneurysm was missed had a technically unsatisfactory examination. Only seven (39%) of the 18 operated patients thought to have abdominal aortic aneurysm who did not undergo op¬ eration had sonograms suggesting this diagnosis. These patients have been observed by periodic ultrasound exam¬ ination for evidence of increasing aneurysm size. No pa¬ tient clinically diagnosed as having aortic aneurysm who had a normal sonogram has developed an expanding aortic mass.
Fig 1 .—Frequency of ultrasonic diagnosis of abdominal masses increased markedly during fifth year (1971) of study. Half-year figures for 1974 are not shown.
Fig 2.—Ultrasound diapnosis (DX) of abdominal mass was eval¬ operatively in 43% of patients. In remainder, sonography was compared to nonopeiative clinical diagnosis. uated
Intraperitoneal
Thirty-three patients, studied preoperatively by ul¬ trasound, were found at laparotomy to have intraperito¬ neal masses in areas not previously described. Nineteen (58%) were diagnosed correctly by ultrasound. A total of 23 patients who underwent operation were found to have one or more intraperitoneal abscesses measuring at least 3 cm in diameter. In 14 (61%) the size and location of the ab¬ scess was accurately predicted by sonography (Table 4). The success of ultrasound in localizing intraperitoneal pus is tabulated in Table 5. Subphrenic abscess was identified in six (75%) of eight patients. Subhepatic abscess was found in two of four patients and appendiceal abscess in three of four. Abscesses of the lesser sac and the right paracolic area were missed in separate patients. Intraperitoneal masses in other patients who had un¬ dergone operation included ovarian cyst (two), uterine myoma (one), colon carcinoma (two), mesenterie cyst (one), urinary bladder carcinoma (one), hematoma (two), and metastatic cervix carcinoma (one) (Table 4). A preop¬ erative sonographic diagnosis identified the mass in five (50%) of ten patients. Twenty-one patients had a clinical diagnosis of intra¬ peritoneal abscess but did not undergo laparotomy.
Table 2.—Ultrasound Accuracy in Patients Who Underwent Operation*
Table 1,—Site of Abdominal Masses* Site Liver Gallbladder
Correct
Patients
Patients Not
Operated On
Operated On
Total
9 8
11 3
20 11
23 16 8 33
40 37 18 31
63 53 26 64
Site of Mass Liver Gallbladder
Spleen Pancreas
Kidney Aorta
Intraperitoneal Retroperitoneal
Spleen
Site confirmed in 105 patients who were operated pected in 141 patients who were not operated on. *
Pancreas
Kidney Aorta
Intraperitoneal·
Diagnosis 5 (56%) 3 (38%) 5 (100%) 11 (48%) 9 (56%) 7 (88%)
Patients 9 8 5 23 16 8 33
on
and
sus¬
Ultrasonic diagnosis of abdominal patients who underwent operation. *
correct in
_
mass
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(58%) (33%) 60 (57%) of
19 1
Retroperitoneal_3
Twelve (57%) of these patients had ultrasonic evidence of abscess. Among ten other patients with suspected in¬ traperitoneal lesions who did not undergo operation, six (60%) had sonograms that agreed with the clinical diag¬ nosis. Positive correlation of ultrasound with the clinical diagnosis in a total of 31 patients with intraperitoneal mass who did not undergo operation was 58% (Table 3).
Table 3.—Ultrasound Accuracy in Patients Who Did Not Undergo Operation* Correct
Site of Mass Liver Gallbladder
Kidney
Para-aortic adenopathy constituting a palpable abdomi¬ nal mass was discovered surgically in three patients. One had been diagnosed by preoperative ultrasound scan
False-Positive
40 37
13 26 7
31
18 0
Aorta
Intraperitoneal Retroperitoneal
Ultrasonic diagnosis agreed with clinical diagnosis patients who did not undergo operation.
vs
False-Negative
Table
The nature of ultrasonic misdiagnosis is analyzed in Table 6. Among 45 patients who underwent operation, 25 (56%) had a false-positive diagnosis and 20 (44%) had a false-negative interpretation of sonograms. False-posi¬ tive diagnoses were more common with renal masses and intraperitoneal abscess. A false-negative impression was responsible for four of five missed gallbladder diagnoses.
Patients
Liver Metastatic carcinoma
Abscess
Cyst Gallbladder Distention
During the seven years of this study, B-scan ultrason¬ ography was introduced and popularized as a means of diagnosing abdominal masses. Errors of interpretation during early experience were due to limited training, lack of diagnostic criteria, and variability of equipment. Such factors no longer pertain, but it is obvious that ultrasound is still of limited value in defining the nature of many ab¬
Spleen Splenomegaly
sources
of error in
diagnosing aortic an¬
eurysm are (1) enlarged periaortic lymph nodes that can¬ not be acoustically separated from aorta and (2) excessive
(49%)
Operation* Diagnosis 5 0 0
(71%)
3 0
(75%)
Rupture Pancreas
Pseudocyst Carcinoma Pancreatitis
14 6 3
9 2 0
(64%) (33%)
2 4 2 1 0
(40%) (100%) (67%) (50%)
7
(88%)
Kidney Carcinoma
techniques.
in 69
3 (100%) 1 (100%) 1 (100%)
Hematoma
masses.
Other potential
(33%) (70%) (39%) (58%)
Correct Mass
Stones
Surprisingly few studies have evaluated the accuracy of ultrasound diagnosis of nonobstetric abdominal masses since the initial report of the technique by Howry and Bliss in 1952.4 Limitations of sonography were described by Holm1 in his review of patients with lesions in the up¬ per part of the abdomen. While solid or cystic masses mea¬ suring at least 2 to 3 cm in diameter were readily de¬ tected, smaller lesions or those covered by gas-filled intestine were not. Recently, attention has been drawn to the accuracy of ultrasound in detecting abdominal aortic aneurysm.2 The elastic walls of the aorta constitute a distinct acoustic density making the structure easy to identify. Aneurysms can be measured with an accuracy of ± 3 mm and echoes from thrombi within the vessel often can be demonstrated. Our experience confirms that ultrasonography is an ideal means of diagnosing and following up abdominal aortic aneurysm. The only false-negative result was due to bowel gas, which prevented adequate sound penetration of the aneurysm. To a great extent, this error can be obviated by
(33%)
4.—Accuracy of Ultrasound in Diagnosing Abdominal Mass in Patients Who Underwent
COMMENT
newer
1
*
single patient who had not undergone operation was presumed to have retroperitoneal adenopathy but this was not confirmed sonographically.
dominal
11
0
Pancreas
A
Diagnosis 4 (36%:
Spleen
Retroperitoneal
(Table 4).
Patients
Single cyst Stones
Multiple cysts
Abscess Aorta
Aneurysm
Intraperitoneal Abscess
Ovary-uterus Colon Other
23 3 2 5
14 (61%) 2 (67%) 1 2
(50%) (40%)
1
(33%:
Retroperitoneal Nodes
*
Among patients who underwent operation, accuracy of ultrasonog¬ raphy was highest for splenic masses and aortic aneurysm and lowest for gallstones.
gain settings on B-scan equipment that obscure the aneu¬ rysm, since intraluminal thrombus produces echoes at high gain. The ability of ultrasound to define the nature of splenic masses in all patients studied was an unexpected finding of this study. The high posterior position of the spleen should make it less acoustically accessible than other ab¬ dominal organs. Scanning is done between the ribs so that
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Fig 3.—Line of echoes patient (arrow). Diagnosis
laparotomy.
within sonolucent of splenic rupture
spleen was
of trauma confirmed by
bone echo artifacts do not produce false-positive echoes within the spleen. Small splenic lesions shadowed by the ribs might be obscured altogether. Gas in either the splenic flexure of the colon or the fundus of the stomach might also prevent adequate sound penetration for vis¬ ualization of the spleen. The diagnostic detail seen in two patients with splenic trauma suggests that sonography be used routinely to evaluate trauma patients suspected of having delayed rupture of the spleen. The repeatable, noninvasive nature of the technique has special application in such patients. The usefulness of ultrasound for diagnosis of hepatic masses is considerably less than for aortic and splenic masses. With present equipment, the diameter of solid le¬ sion, such as liver métastases, must exceed 3 to 4 cm be¬ fore the mass can be identified. Such extensive metastatic disease was present in our patients with abnormal scans. Métastases may appear (1) as patches of echoes within the sonolucent liver, (2) as sonolucent areas when the liver is scanned at high gain settings, or (3) as doughnut-like echoes with an outer ring of acoustical density and an in¬ ner sonolucent area. At present, ultrasound cannot con¬ tribute decisively to the differential diagnosis between cirrhosis and métastases.1 We were disappointed that sonography failed to detect fluid-filled spaces in the livers of two patients. Subsequent
Table 5.—Ultrasound
Accuracy In Localizing Intraperitoneal Abscess* Correct
Abscess Site
Patients
Subphrenic, right Subphrenic, left Subhepatic Lesser
Fig 4.—Sonolucent area (arrow), in head of pancreas, which, contrary to ultrasound diagnosis, proved to be small pseudocyst.
3 5 4 1 4
sac
Appendiceal Paracolic Pelvic *
0 3 2
4 1
Abdominal wall
Overall accuracy of ultrasound in 61%.
Diagnosis 2 (67%) 4 (80%) 2 (50%)
1
(75%) (50%) (100%)
localizing intraperitoneal ab¬
scess was
in
Fig 5.—Sonolucent space (arrow) representing aortic aneurysm patient
whose
aortogram showed
no
Table 6.—Nature of Ultrasonic Misdiagnosis in Patients Who Underwent Operation*
aneurysm.
Site of Mass Liver (4) Gallbladder (5)
False-Positive
False-Negative
3
1
Spleen (0) Pancreas (12)
Kidney (7) Aorta (1)
Intraperitoneal (14) Retroperitoneal (2)
10
Of 45 patients who underwent operation and who were misdiagnosed by ultrasound, 25 (56%) had false-positive and 20 (44%) had *
false-negative interpretations.
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that intrahepatic abscesses of less than 3 cm diameter will be missed in half of the patients studied by B-mode scanning. As confirmed in this study, ultrasound appears to have no advantage over roentgen cholecystography in detect¬ ing gallstones.5 Respiratory motion can obscure echoes from gallstones. Furthermore, a stone must be of suffi¬ cient size (0.5 to 1.0 cm) and have adequate acoustic differ¬ ence from bile to produce detectable echoes. Reverber¬ ation artifacts from ribs and the anterior body wall can produce echoes within the gallbladder that might be mis¬ taken for gallstones. Ultrasound may be of value, how¬ ever, in cases of roentgenographic nonvisualization of the gallbladder or in patients who cannot tolerate cholecystog¬ raphy.6 Since sonography does identify gallbladder dis¬ tention with reasonable accuracy, it may prove to be of some use in patients with obstructive jaundice. Also disappointing was the low rate of accuracy of ul¬ trasound in diagnosing pancreatic disease. Other reported experience suggests that pseudocysts might be detected with accuracy approaching 90%.79 Instead, only two thirds of our pseudocyst patients were correctly diagnosed. False-positive errors were reduced in more recent experi¬ ence by recognizing the echo pattern of massive edema surrounding the inflamed pancreas. Occasional false-posi¬ tive or false-negative interpretations are apt to continue since differentiating between small pseudocysts in the head of the pancreas and edema of that portion of the gland may not be possible with B-mode equipment. There is no doubt that ultrasound is of great help in fol¬ lowing up the development of pancreatic pseudocyst once a sonolucent mass has appeared.10 Our results suggest that B-mode scanning has appli¬ cation in the diagnosis of both solid and cystic renal
experience suggests
Whether it has advantage over established tech¬ as pyelography and angiography has not been such niques shown. While admittedly not a screening technique, ultra¬ sonography might have application in the treatment of cystic renal lesions. A mass detected by pyelography, shown to be cystic by sonography, could be aspirated with¬ out the need for prior angiography. Holm et al11 have pre¬ viously described the use of ultrasound in localizing perinephric abscesses and other masses. Ultrasound provides one means of finding localized pus in the abdomen. Initial reports of its use for this purpose were encouraging.2 Successful diagnosis occurred in 61% of our patients. Intraperitoneal abscesses and hematomas can be identified by the presence of echo-free areas that disturb the normal shape or position of organs. Air-filled intestine overlying the abscess might reflect sound, pre¬ venting diagnosis. Another problem in patients with ab¬ scess is the frequency with which multiple incisions and wound appliances prevent adequate abdominal scanning. It is unlikely that intraperitoneal abscesses measuring less than 2 to 3 cm in diameter will be detected with accuracy by current ultrasonic techniques. Retroperitoneal masses have only a limited chance of being detected by ultrasound. A retroaortic mass dis¬ placing the abdominal aorta from the lumbar vertebrae can be found with greater accuracy.12 New developments in ultrasound technology hold prom¬ ise of improving sonographic diagnosis of abdominal masses. One such advance is the use of gray scale ultra¬ sonography by which lesions as small as 1 cm may be dis¬ covered in previously obscure areas such as liver. It is likely, therefore, that ultrasound will retain a place among various diagnostic techniques to identify and localize the obscure abdominal mass. masses.
References 1. Holm HH: Ultrasonic scanning in the diagnosis of space-occupying lesions of the upper abdomen. Br J Radiol 44:24-36, 1971. 2. Leopold GR, Goldberger LE, Bernstein EF: Ultrasonic detection and evaluation of abdominal aortic aneurysms. Surgery 72:939-945, 1972. 3. Jensen F, Pedersen JF: The value of ultrasonic scanning in the diagnosis of intra-abdominal abscesses and hematomas. Surg Gynecol Obstet 139:326-328, 1974. 4. Howry DH, Bliss WR: Ultrasonic visualization of soft tissue structures of the body. J Lab Clin Med 40:579-592, 1952. 5. Doust BD, Maklad NF: Ultrasonic B-mode examination of the gallbladder: Technique and criteria for the diagnosis of gallstones. Radiology
110:643-647. 1974. 6. Goldberg BB, Harris K, Broocker W: Ultrasonic and radiographic cholecystography. Radiology 111:405-409, 1974. 7. Bradley EL, Clements JL: Implications of diagnostic ultrasound in the
of pancreatic pseudocysts. Am J Surg 127:163-173, 1974. 8. Stuber JL, Templeton AW, Bishop K: Sonographic diagnosis of pancreatic lesions. Am J Roentgenol Radium Ther Nucl Med 116:406-412,1972. 9. Filly RA, Freimanis AK: Echographic diagnosis of pancreatic lesions, ultrasound scanning techniques and diagnostic findings. Radiology 96:575\x=req-\ 582, 1970. 10. Bradley EL, Clements LJ: Spontaneous resolution of pancreatic pseudocysts: Implications for timing of operative intervention. Am J Surg 129:23-28, 1975. 11. Holm HH, Kristensen JK, Rasmussen SN, et al: Ultrasonic diagnosis of juxtarenal masses. Scand J Urol Nephrol 15(suppl 6): 83-88, 1972. 12. Spirt BA, Skolnick ML, Carsky EW, et al: Anterior displacement of the abdominal aorta: A radiographic and sonographic study. Radiology 111:399-403, 1974.
surgical management
Discussion Roger F. Smith, Md, Detroit: I am in agreement that ul¬ trasound examination is becoming an increasingly important ad¬ junct in the differential diagnosis of abdominal masses. Our chief experience at the Henry Ford Hospital with echography has been in patients with abdominal aortic aneurysms, where it appears to have some definite limitations. Fortunately, most abdominal aneurysms can be diagnosed by
physical examination or by an anteroposterior and lateral roentgenograms for aortic calcification. When the problem of the diagnosis of a pulsatile mass cannot be resolved by these simpler means, we prefer to go directly to a translumbar aortogram as the definitive study. We have found in the case of an abdominal aortic aneurysm that the added information obtained by this method as to the state of the vesical, pelvic, and distal circulation is of great careful
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benefit to us in planning a proper operation. In contrast, however, if a nonpulsatile midabdominal mass is felt, then an echogram is our first choice as the least noninvasive form of examination to rule out an abdominal aneurysm and to determine if the lesion is solid or cystic. One serious limitation that we have observed in the diagnostic use of ultrasound has been in its inability to accurately differ¬ entiate between a retroperitoneal lymphoma and an abdominal aneurysm. This has not been a rare clinical problem in our concen¬ trated vascular practice. It is our opinion that ultrasound, at its present level of perfec¬ tion, must assume a secondary role to aortography in the differ¬ ential diagnosis and management of abdominal aneurysms. Alexander J. Walt, MD, Detroit: We have used a fair amount of ultrasound in one of our affiliated hospitals, and recently had the radiologist who does it there give us an update. I think one has to look at the state of the art, and if it is possible to make some predictions, I would suggest (as others have) that ten years from now ultrasound will have replaced possibly 40% to 50% of what we currently are doing in our radiological departments. If one looks at this in the light of roentgenograms where roent¬ genograms were in the year 1910—and see the distance roentgen¬ ography has come since then, I suspect we are looking at ul¬ trasound in terms of a similar infancy. With the new gray scale types of techniques, the experts are able to show all sorts of de¬ tails. We even had stones in the common duct beautifully shown to us, and lesions in the aorta, the takeoff of the superior mesenterie artery, and even the inferior mesenterie. We, too, have had some disappointments in trying to delineate pseudocysts of the pan-
creas, but it may well be that we ask too much of the technique at present. I am not sure whether Dr. Norton is disappointed with
or pleased with them. We have, on occasion, had some great triumphs where ultrasound has helped our surgery. Dr. Norton, have you analyzed your cases in terms of the value
his results
of sonography to you in the years 1967 to 1972 and the years from 1972 until now? I suspect your radiologists are much more helpful to you today than they were then. I enjoyed the paper, and wish to reiterate that I believe that within five years sonography will be a very common and invalu¬ able investigation in the delineation of abdominal surgical condi¬ tions. Dr. Norton: Dr. Smith's much wider experience with aneurysm confirms our general position that ultrasound is currently of sec¬ ondary importance in diagnosing abdominal masses, although for aortic disease it is probably more accurate than for other organs. In answer to Dr. Walt's question, we agree entirely that the success of diagnosis has been improving, and in recent years with experience our ultrasonographer, I think, is more accurate. There is no question that gray scale scanning should improve our ability to pick up smaller lesions. We are talking about detection in the area of 0.5 to 1.0 cm vs our current B-mode accuracy of about 3 to 4 cm. That is hopeful. We were disappointed in our accuracy of detecting pseudocysts. Sixty-four percent, we thought, was disappointing in view of ar¬ ticles that had suggested an accuracy as high as 90%. Compared to reports published previously, we were disappointed, but perhaps we are asking too much.
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