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Objective: The purpose of this study was to compare liver signal-to-noise ratio (SNR), lesion SNR, and lesion-liver contrast-to-noise-ratio (CNR) in patients with malignant liver lesions after the administration of a standard dose (0.1 mmol/kg of body weight) or a triple dose (0.3 mmol/kg) of a gadolinium chelate (gadoteridol). We hypothesized that the higher dose would produce a higher lesion-liver CNR and therefore increase the conspicuity of hepatic lesions., Materials and Methods: A total of 85 patients with malignant hepatic masses (61 metastases, 22 hepatocellular carcinomas, and two lymphomas) proved by histologic or follow-up studies underwent MR imaging at 1.5 T. T1-weighted spin-echo imaging and gradient-echo imaging were done before and within 1 min after (gradient echo) as well as 5 (spin echo) and 15 (spin echo) min after the injection of 0.1 or 0.3 mmol of gadoteridol per kg, randomized before the start of the study (39 patients received the standard dose, and 46 received the triple dose). The signal intensities of the liver and lesions and the SD of background noise were measured by use of regions of interest to calculate the SNR of the liver and malignant lesions and the lesion-liver CNR., Results: The lesion-liver CNR was increased significantly at 5 and 15 min after the administration of gadoteridol. No significant differences in the liver SNR, lesion SNR, and lesion-liver CNR (after 1 min: standard dose, -5 +/- 8, and triple dose, -4 +/- 14; after 5 min: standard dose, -1 +/- 5, and triple dose, 2 +/- 8; and after 15 min: standard dose, 1 +/- 5, and triple dose, 6 +/- 20) were found between the doses at all time points., Conclusion: Triple-dose gadoteridol does not improve the lesion-liver contrast of malignant hepatic lesions over that provided by the standard dose and is not warranted for liver MR imaging.

Objective: Because of pending efforts to reform health care in the United States, judicious use of low-osmolality contrast media is important. We studied the effects of using various concentrations and volumes of iohexol, compared with the conventional dose and concentration of diatrizoate meglumine used for CT, to determine if a more cost-effective dose results in diagnostically efficacious liver enhancement., Subjects and Methods: A total of 902 patients received one of nine different doses of IV contrast media. Eight doses of iohexol were used: 125 ml of iohexol 350 (350 mg l/ml, 44 g l/dose), 100 ml of iohexol 350 (35 g l/dose), 150 ml of iohexol 300 (300 mg l/ml, 45 g l/dose), 120 ml of iohexol 300 (36 g l/dose), 100 ml of iohexol 300 (30 g l/dose), 175 ml of iohexol 240 (240 mg l/ml, 42 g l/dose), 150 ml of iohexol 240 (36 g l/dose), and 125 ml of iohexol 240 (30 g l/dose). A single dose (150 ml) of diatrizoate meglumine 60% (w/v) was used (42 g l/dose). Contrast material was injected at a rate of 2 ml/sec. Scanning began 35-45 sec after injection. Quantitative analysis of enhancement was performed by obtaining region-of-interest measurements through the liver on scans obtained before and after injection of contrast material. Mean and maximum changes in hepatic density and mean time to maximum enhancement were measured. Mean time-density curves were subsequently derived for each dose of contrast material. Qualitative analysis of enhancement was performed by using subjective, previously defined criteria. All studies were interpreted in a double-blind fashion., Results: Mean hepatic enhancement was greater with 125 ml of iohexol 350 and 150 ml of iohexol 300 than with other doses of contrast material (p < .05). Both 125 ml of iohexol 350 and 150 ml of iohexol 300 produced actual hepatic enhancement of more than 50 H for over 60 sec. The greatest maximum increase in hepatic density occurred with 125 ml of iohexol 350. When analyzed qualitatively, 150 ml of iohexol 300 resulted in the highest percentage of optimum enhancement., Conclusion: According to quantitative analysis, 125 ml of iohexol 350 administered at a rate of 2 ml/sec produces the best enhancement, whereas according to qualitative analysis, 150 ml of iohexol 300 produces the best enhancement. All doses of iohexol 240 provide poor enhancement compared with a conventional dose of contrast material of 150 ml of diatrizoate meglumine 60% or 150 ml of iohexol 300. A moderate cost savings can be achieved by using 125 ml of iohexol 350 for dynamic sequential CT.

Objective: Spiral CT allows rapid hepatic imaging during a single breath-hold. The increase in imaging speed potentially allows contrast material to be used more efficaciously than with conventional dynamic CT, perhaps allowing a decrease in the volume of required contrast agent. To determine how this can be accomplished, we studied the effect of different bolus IV injection rates and amounts of contrast material on early hepatic enhancement during dynamic bolus spiral CT., Subjects and Methods: A group of 20 healthy male volunteers were divided into four groups of five each. The groups received 75, 100, 125, or 150 ml of contrast material (Omnipaque 300, 300 mg l/ml). Each person within each group was scanned as contrast material was injected at rates of 3, 4, and 5 ml/sec. Hepatic enhancement was evaluated by comparing quantitative regions of interest before and after bolus injection of contrast material. Variations in enhancement produced by changes in volume and injection rate of contrast material were evaluated on early, middle, and late sections of the spiral, corresponding to 32-34, 41-43, and 51-53 sec, respectively, after the injection of contrast material was begun., Results: Hepatic enhancement increased more rapidly when the bolus of contrast material was given at a rate of 5 ml/sec than at the slower rates of 3 or 4 ml/sec. Enhancement of the liver was greatest at the late portion of the spiral (51-53 sec after start of the bolus injection), averaging 73 and 79 H for volumes of 125 and 150 ml, respectively, at 5 ml/sec, and the enhancement was still increasing at that time. Enhancement curves predict 50- and 70-H mean increases in hepatic attenuation on initial slices with scan delays of approximately 40 and 50 sec, respectively, for these two protocols., Conclusion: Our results demonstrate that there is a marked dependence on early hepatic enhancement produced by variations in volume and injection rate of contrast material. We found no difference in the results produced by 125- and 150-ml volumes. These results are important for maximizing the effectiveness of IV contrast material during rapid hepatic spiral CT scanning.

Objective: A multiinstitutional study was performed to evaluate the efficacy of CT during arterial portography for determining the resectability of hepatic tumors. The impact of findings from CT during arterial portography on patients' treatment (i.e., surgical vs nonsurgical) was assessed. In patients considered to have resectable tumors, the accuracy of CT during arterial portography for predicting surgical findings was also evaluated., Materials and Methods: A retrospective study was done of 404 patients from three institutions who had CT during arterial portography during the period 1985-1991 as part of preoperative staging to determine the resectability of hepatic tumors. The tumors included metastases from colorectal carcinoma in 197 patients (49%); other hepatic metastases, mostly from adenocarcinoma of the stomach, pancreas, and biliary tree in 123 (30%); and primary hepatocellular carcinoma in 84 (21%). Imaging results were correlated with results of percutaneous biopsy of at least one hepatic lesion in patients whose tumors were considered unresectable. In patients whose tumors were considered resectable, results were correlated with preoperative percutaneous biopsy (obtained in almost all cases) and pathologic examination of a surgical specimen (all cases). Although each case was considered individually, four criteria were used for resectability: (1) accessibility of all lesions to lobar or wedge resection that would yield clear margins, (2) anticipation that residual liver tissue after resection would provide sufficient function, (3) the absence of invasion of central hepatic vascular or biliary structures, and (4) the absence of extrahepatic disease. No specific restriction was made with respect to the number of hepatic lesions present. The accuracy of findings by CT during arterial portography for predicting resectability was assessed in the 146 patients who had tumors that were considered resectable on the basis of imaging findings and had surgery., Results: Of 404 patients, only 146 (36%) were thought to be candidates for resection on the basis of findings from CT during arterial portography. Of these, 122 (84%) actually had resection. The 24 patients who did not have resection included 22 patients with disease understaged or overstaged by CT during arterial portography, one with true-negative findings by CT during arterial portography, and one who died during surgery. The accuracy of findings by CT during arterial portography for predicting results at surgery was 85% for all patients and 91% for the subset of patients who had primary colorectal tumors with hepatic metastases., Conclusion: Our experience shows that CT during arterial portography is a useful procedure for assessing the resectability of hepatic tumors. In our study, 64% of patients were spared unnecessary surgery.(ABSTRACT TRUNCATED AT 400 WORDS)

The purpose of our study was to determine the frequency of detection of small hepatic lesions (less than or equal to 15 mm) in outpatients who had abdominal CT and to assess the significance of these lesions in the presence or absence of known malignant tumors. Contrast-enhanced abdominal CT scans in 1454 patients were reviewed. In 254 patients (17%), hepatic lesions 15 mm or smaller were detected. In 51% of these patients, lesions were judged benign on the basis of other imaging studies, biopsy results, or stability for at least 6 months as shown by CT. Lesions were judged malignant on the basis of progression seen on radiologic studies or biopsy in 22%. The other 27% of the patients had lesions that could not be classified. The majority of patients with small hepatic lesions (82%) were known to have a malignant tumor; in 51% of these patients, lesions were diagnosed as benign. No patient without a known malignant tumor had a small hepatic lesion that was determined to be malignant. Multiple small lesions were more likely to represent malignant disease than were single small lesions. We conclude that small hepatic lesions are common (seen in 17% of our patients), and that there is a high probability that hepatic lesions smaller than 15 mm are benign, even in patients known to have an extrahepatic malignant tumor.

Six hundred patients were prospectively randomized and given either diatrizoate meglumine 60 or iohexol 300 during dynamic contrast-enhanced body CT in order to compare image quality, contrast reactions, and the number of aborted studies or studies in which images had to be repeated. Three hundred two patients received iohexol 300, and 298 patients received diatrizoate meglumine 60. Thirty-nine percent (119/302) of the patients given iohexol 300 and 63% (188/298) of the patients given diatrizoate meglumine 60 had at least one adverse reaction thought to be related to contrast material during, or within 24 hr of, the body CT scan. When reactions of discomfort (heat or warmth, flushing, bad taste) were excluded, 16% (48/302) of the patients who received iohexol and 33% (99/298) of the patients who were given diatrizoate meglumine 60 had at least one adverse reaction. The differences in both types of reactions between the two agents were significant (p less than .001). Among scans evaluated for study quality, 71% (214/302) of the iohexol 300 group and 62% (184/298) of the diatrizoate meglumine 60 group had optimal enhancement (p = .02). However, when the optimal and adequate categories were combined, 301 of 302 patients given iohexol 300 and 292 of 298 patients given diatrizoate meglumine 60 had diagnostic-quality studies (no statistical difference). Studies were not terminated nor were images repeated in 97% (292/302) of the patients given iohexol 300 and in 94% (280/298) of those given diatrizoate meglumine 60. The CT study was repeated because of movement during the contrast injection or aborted because of contrast-related reactions in 0.7% of the patients given iohexol 300 and in 3.0% of the patients given diatrizoate meglumine 60. This difference was statistically significant (p = .04). Our results suggest that the difference in image quality, number of adverse reactions, and number of aborted/repeated CT scans performed with iohexol 300 or diatrizoate meglumine 60 are not sufficiently different to warrant conversion to nonionic agents for body CT scans.

Sixteen MR studies performed in four patients who had undergone combined pancreatic and renal transplantation were reviewed retrospectively to determine if dynamic gadopentetate dimeglumine-enhanced gradient-echo imaging is useful in the early diagnosis of pancreatic transplant rejection. The MR studies were performed between 3 days and 6 months after transplantation and consisted of T1- and T2-weighted spin-echo images as well as a gradient-echo image prior to administration of an IV bolus of gadopentetate dimeglumine (0.1 mmol/kg). After injection of gadopentetate dimeglumine, a static dynamic gradient-echo scan was obtained. Signal-intensity measurements were determined for each of the gradient-echo images and used to generate an enhancement curve. Because T2 values have previously been used as an objective indicator of rejection, the mean T2 of each pancreatic transplant was calculated also. The MR results were compared with clinical and laboratory data and/or percutaneous biopsy results. In six studies of normally functioning pancreatic allografts, the percent enhancement during the first minute of the enhancement curve was 98 +/- 23% (1 SD). In six episodes of acute dysfunction (rejection or infarction), the first-minute enhancement was 42 +/- 20%. In four cases of dysfunction, the finding of an abnormal enhancement curve preceded a significant drop in urinary amylase by 1-4 days. The calculated T2 value was prolonged in only two cases in which biopsy-proved pancreatic infarction had occurred. No prolongation of T2 was evident in four cases of rejection alone. These results suggest that mean T2 calculation at 1.5 T may not be a reliable indicator of pancreatic transplant rejection, but that gadopentetate dimeglumine-enhanced gradient-echo MR imaging of the pancreatic transplant may be a reliable early indicator of pancreatic transplant dysfunction.

We determined the density in Hounsfield units of the mesenteric, retroperitoneal, and subcutaneous fat on CT scans made in 41 patients with biopsy-proved cirrhosis and compared the results with the density of the fat in these locations in 34 control subjects, in an attempt to quantify changes in fat density in patients with cirrhosis. The mean densities of mesenteric, retroperitoneal, and subcutaneous fat in patients with cirrhosis were -56, -107, and -111 H, respectively. The corresponding mean densities in control subjects were -107, -118, and -124 H. The mean density of mesenteric fat in patients with cirrhosis was 50% greater than that of their subcutaneous fat (p less than .0001), 48% greater than that of their retroperitoneal fat (p less than .0001), and 48% greater than that of the mesenteric fat in control subjects (p less than .0001). The mean density of subcutaneous fat in the anterior abdominal wall in patients with cirrhosis was -96 H compared with -119 H for that in their posterior abdominal wall. The corresponding mean densities in control subjects were -109 and -131 H. Density of subcutaneous fat in the anterior abdominal wall for all subjects (patients and controls) was 18% greater than that of subcutaneous fat in the posterior abdominal wall (p less than .05). In all locations, the statistical trend was for patients with cirrhosis to have higher density fat than did control subjects. These changes in density are thought to represent diffuse fat edema, most prominently in the mesentery because of portal hypertension.

Pneumothorax is the most common complication after CT-guided pulmonary interventional procedures and should be promptly diagnosed and treated. Because it is easier to obtain CT scans than chest radiographs after CT-guided interventional procedures, it is important to know the sensitivity of CT in detecting pneumothoraces. To determine the sensitivity of CT for detecting procedure-induced pneumothoraces, we retrospectively reviewed 70 pulmonary interventional procedures performed under CT guidance. The sensitivity for detecting pneumothoraces with CT was compared with the detection rate with expiratory chest radiographs. Thirty-two (46%) of 70 procedures resulted in pneumothorax. Twenty-nine (91%) of the pneumothoraces were detected on CT scans and 27 (84%) were detected on chest radiographs. The difference between these two detection rates was not statistically significant (p less than .90). We conclude that postprocedure CT scans can replace expiratory chest radiographs for the detection of pneumothoraces after CT-directed pulmonary procedures.

Ultrasonic characteristics of 21 adrenal neoplasms (19 patients) examined by gray scale ultrasonography are reviewed. The significance of the adrenal-renal cleavage plane is discussed. In our experience the cleavage plane only has definite localization value when it separates the adrenal gland from the kidney on all ultrasonographic sections. Compression of the posterior wall and/or anterior displacement of the inferior vena cava was seen in about two-thirds of the right adrenal tumors. The difficulty in examining left adrenal masses is emphasized. Ultrasonography has proved to be an excellent screening procedure for adrenal tumors.

We conducted a randomized, blinded, prospective study evaluating hepatic parenchymal density changes during dynamic bolus CT (180 ml of contrast material given IV) and delayed CT (5 hr after 60 g of iodine) in order to compare the enhancement characteristics of an ionic contrast agent (iothalamate-60) and two nonionic agents (iohexol-300 and iopamidol-300). A total of 75 patients with known or suspected cancer were studied (25 patients per contrast agent). After a baseline unenhanced CT scan was obtained, dynamic bolus and delayed CT scans were obtained for all patients with one of the three contrast agents. The density of the liver and spleen was measured in Hounsfield units (H) for unenhanced CT, dynamic bolus CT, and delayed CT. The average percentage of enhancement was calculated as follows: postcontrast density minus precontrast density was divided by precontrast density and then multiplied by 100. For dynamic bolus CT, the average percentage of enhancement of the liver was 105% when iohexol-300 was used, 98% when iopamidol-300 was used, and 83% when iothalamate-60 was used. No significant difference was seen between the postcontrast enhancement of the three contrast agents on dynamic bolus CT scans (p greater than .05). For delayed CT, the average percentage of enhancement of the liver was 34% when iothalamate-60 was used, 28% when iopamidol-300 was used, and 16% when iohexol-300 was used. Both iothalamate-60 and iopamidol-300 showed superior enhancement on delayed CT, compared with iohexol-300 (p = .0001). We conclude that for dynamic bolus CT, all three contrast agents are similar, with no statistically significant differences in postcontrast enhancement of the liver. For delayed CT, however, hepatic enhancement with iothalamate-60 and iopamidol-300 is statistically superior to that with iohexol-300.

Twenty-one human hepatic liver biopsy samples were evaluated by nuclear magnetic resonance spectroscopy. This spectroscopy was performed by obtaining multiple and not single T2 values (T2-long and T2-short). Neoplastic tissue had greater T2-long and T2-short values than diffuse liver disease. The T2-short correlated, r = 0.947 (p less than 0.01), with the percentage of cancer cellularity within the tissue specimens. There was no correlation between the multiple T2 values and the degree of fibrosis and inflammation. Minimal correlation was noted between the T2-long and percentage of fat within the diffuse disease (cirrhotic) specimens, r = 0.636 (p less than 0.05). The possible reasons for the above findings are discussed.

Experience with computed tomography (CT) in 25 patients with histologically proven osteosarcoma is presented. CT was as accurate as conventional radiographic methods in determining the presence of a lesion, but it was definitely superior in defining the extent of disease, particularly intramedullary extension and soft tissue extraosseous tumor component. CT was capable of demonstrating skip metastases in one patient. CT plays a key role in the preoperative evaluation of osteosarcoma patients, particularly when less than radical surgery is planned as primary treatment and when postoperative recurrence is suspected. CT is also useful in assessing the response to therapy in nonsurgical cases. The technique involved in the performance of this examination is discussed.

Fifty-eight percutaneous needle biopsies of adrenal masses were performed in 53 patients. The technique was initially successful in 44 (83%) of 53 patients. Five patients had second procedures because of initial failure or the possibility of sampling error. Fourteen biopsies were performed in nononcologic patients and 39 in patients with a known malignancy. None of the adrenal masses in nononcologic patients were malignant. Only 18 (46.1%) of the 39 masses in oncologic patients were metastases; the rest represented a variety of nonneoplastic conditions. Seven minor complications occurred in six patients. Two of these patients required transfusions for hypotension or decreases in hematocrit. No correlation was noted between needle size and complications. There were no pneumothoraces. The procedure is an accurate and safe alternative to surgical biopsy.

Fifty-six MR studies were obtained in 32 renal transplant patients, by using T1-weighted, spin-echo, and inversion-recovery pulse sequences. The findings, particularly the loss of corticomedullary differentiation, and the extent of vascular penetration into the renal parenchyma, were compared with the clinical and histologic diagnosis of transplant rejection. Thirteen MR studies on 11 patients with clinically normal renal transplants demonstrated normal corticomedullary differentiation. Renal vessels extended into the parenchyma in all 11 patients and to the cortex in 38%. In 37 MR studies on 22 patients with a clinical or histologic diagnosis of acute and/or chronic transplant rejection, the corticomedullary differentiation was normal in 8%, faint in 24%, and absent in 68%. Renal parenchymal vessels were visualized in 32%, but extended to the level of the cortex in only 8%. In 68% of the studies with transplant rejection, no parenchymal vessels were seen. When the corticomedullary differentiation was either faint or absent, the vascular pattern was normal in 6%; in 68% of cases no parenchymal vessels could be identified. We conclude the corticomedullary differentiation and the renal vascular pattern are useful parameters in the evaluation of renal transplant rejection.

Seven patients with necrotic liver metastases were evaluated by computed tomography. The metastases demonstrated low attenuation areas varying from a small central portion to the entire lesion. Other findings included mural nodules and fluid-fluid levels. Possible etiologies for necrotic metastases are presented and their differential diagnosis is discussed.

Aortic calcification, either mural or thrombus, is a common finding in patients with abdominal aortic aneurysms. Differentiating between the two sites of calcification is necessary in order to avoid confusing simple thrombus calcification with displaced calcified intima in aortic dissection. The CT scans of 145 cases of abdominal aortic aneurysm and seven cases of abdominal aortic aneurysm with dissection were analyzed with respect to the location of the calcification: mural only or mural and thrombus. Mural calcification was seen in all 152 patients with aneurysms whereas thrombus calcification was identified in only 33 (24%) of the 136 patients with thrombus. Displaced intimal calcification caused by aortic dissection can either appear similar to or, at times, be indistinguishable from thrombus calcification. Thrombus calcification was present in four (57%) of the seven patients with abdominal aortic aneurysms and dissection. To avoid the possibility of a false-positive diagnosis of aortic dissection in patients with abdominal aortic aneurysm, other signs of aortic dissection should be sought such as separation of the true and false lumina by an intimal flap.

Forty-two MR examinations and hepatic panangiograms in 38 patients with portal hypertension were correlated with MR images to determine the ability of MR to detect portal vein hemodynamics. These studies were prospectively analyzed for degree of portal perfusion and direction of flow, portal vein thrombosis, and presence and type of shunt surgery. Thirty-three MR examinations were determined to have grade I (good) or II (fair) portal blood flow. Twenty-nine of these were grade I or II by angiography; the other four were grade IV. Of the eight cases documented as grade IV (hepatofugal portal blood flow) by angiography, none were considered grade IV by MR, suggesting that MR was unable to detect retrograde flow. The other case was not graded because of cavernous transformation of the portal vein. MR correlated well with angiography for the detection or absence of portal vein thrombus, agreeing with angiography in 41 of 42 cases. Two angiographically proven cases of portal vein thrombosis were correctly identified on MR. MR correctly identified the absence of portal vein clot in 39 of 40 angiographically negative cases. MR and angiography also agreed in 41 of 42 cases that a shunt was either present/absent or patent/occluded. The single error was due to inadequate MR scanning in the region of interest. The results show that MR cannot be used to grade blood flow in the portal vein. However, MR accurately detects portal vein thrombosis and the patency of surgical shunts.

In seven (18%) of 39 liver transplantation patients, serial Doppler sonographic examinations performed in the first 2 weeks after the transplantation showed transient, highly echogenic nonshadowing particles moving within the portal vein, believed to be portal venous air. This finding was associated with sepsis in one patient, a positive stool culture for Clostridium difficile in another, and postoperative ileus in a third patient. A fourth patient had primary graft failure and required a second transplant. No potential cause was found in the other three patients. None of the patients had bowel infarction or necrosis. The finding was not associated with transplant rejection or graft infection. We conclude that the sonographic finding of portal venous gas is common in the first 2 weeks after hepatic transplantation and may not have grave prognostic significance.

Sonographic image manipulation became a possibility with the advent of digital equipment. Depending on the manufacturer, this manipulation may be called pre-data processing, post-data processing, or both. It involves changing the normal assigned gray scale curve to accentuate defined decibel ranges. Sixty consecutive patients were examined who had technically adequate hepatic sonograms using the normal linear gray scale range and post-data processing (PDP). Sonograms were considered normal in 32 patients, while 28 were believed abnormal. In 10 of the 28 abnormal scans, hepatic metastases were better visualized with post-data processing (one false-positive). These were patients in whom there was a minimal echogenic difference between the surrounding normal liver and the lesion. However, in no case was a lesion seen after post-data processing that was not recognizable on the linear gray scale scan. In the other 18 abnormal scans (one false-positive study), the echogenic difference between the lesion and the liver was large enough that PDP was not helpful. The possible pitfalls in the use of PDP, such as poor technique, are discussed and demonstrated. Improvement in hepatic sonographic sensitivity will require more fundamental improvement of equipment than provided by post-data processing.

Twenty-five patients with pancreatic pseudocysts had therapeutic intervention procedures that included diagnostic aspiration, short-term drainage (aspiration until completely drained), and long-term catheter drainage. Diagnostic aspirations were used to classify the pseudocysts as infected or noninfected. Short-term drainage was performed on six pseudocysts (two infected and four noninfected) with little success. One resolved and five recurred. Fifteen pseudocysts were treated by long-term catheter drainage. Eight of these (four infected and four noninfected) resolved after initial long-term drainage; two others resolved after additional drainage. The cure rate in these 15 patients was 67%. The other five patients were treated surgically after they had been stabilized but not cured by percutaneous drainage. Complications were few and uniformly minor except for one pneumothorax. Percutaneous aspiration should be used in the diagnosis of pancreatic fluid collections. In noninfected pseudocysts, drainage can be curative. In infected pseudocysts, percutaneous drainage is useful to stabilize the patient and can be either a cure or a temporizing measure until surgery can be performed.

The computed tomographic findings of 30 mesenteric masses are presented. To delineate the mesentery accurately, oral contrast material must fill the entire small bowel. Of the masses, 23 were secondary to non-Hodgkin's lymphoma. These masses were irregular in shape and homogeneous in their tissue attentuation. Two of the 23 had a normal lymphangiogram in the upper paraaortic area. Both lymphangiography and CT were necessary to define the extent of disease in such patients. The six mesenteric metastases were irregular in shape. Four of these had areas of decreased attentuation eccentrically located within the mass which may be secondary to necrosis. One mesenteric cyst had a circular shape with smooth, sharp borders, and a centrally located area of decreased attenuation.

The computed tomographic (CT) findings in 10 patients with pheochromocytoma are presented. Three of 10 patients had multiple endocrine adenomatosis, all with bilateral adrenal masses. One other patient had bilateral adrenal masses, four had right, and one had left sided adrenal masses. One tumor was extraadrenal. CT, when used as the initial imaging study, correctly identified nine of nine pheochromocytomas in six patients. In another four patients, recurrent or metastatic disease was identified. CT findings of use in diagnosis were mass lesions, some with areas of decreased attenuation indicating hemorrhage, and metastases identified in liver, mediastinum, lung, and spine. CT differentiation of benign from malignant lesions is facilitated by demonstration of local invasion or metastasis. CT is recommended as the initial radiographic procedure in the evaluation of patients with clinical or biochemical suspicion of pheochromocytoma, and for follow-up examination in patients with evidence of recurrent disease.

One hundred and two follow-up CT studies in 50 patients with a diagnosis of lymphoma were reviewed to determine the efficacy of limited CT studies for determining therapy. The overall correlation between the limited CT study and the complete CT study was 98%. No mixed responses occurred in 102 cases. Two patients, both with diffuse histocytic lymphoma treated by chemotherapy, showed progression of disease outside a stable tumor bed not detected by a limited CT study. The economic implications, technique, and limitations of limited CT studies are presented.

Orbital pseudotumor is a benign inflammatory lesion of the orbit. Computed tomography is a new method for evaluation of orbits. Scleral uveal rim thickening with contrast enhancement was found in eight of 15 patients with pseudotumor (53%). Similar rim thickening was seen in one postoperative patient and two cases of recent trauma. Therefore, the sign presumably represents inflammation. It was not seen in 47 cases of thyroid disease and 66 cases of neoplasm.

A prospective study was undertaken to determine the incidence of spontaneous extravasation of contrast in 82 patients with acute renal colic. The extravasation rate among 37 patients receiving 75 ml of contrast was 8.1%, while the rate among 45 patients receiving either 300 ml of 30% solution by infusion or a 140 ml bolus dose was 24.4%; overall the rate was 17%. Thus the incidence of extravasation was shown to increase with higher doses of contrast media. The primary dose in acute renal colic or other forms of obstructive uropathy should be in the low range (20-25 g 1-); reinjection after screening can be undertaken if necessary.

For evaluation of the feasibility and clinical potential of using the phase data from standard MR imaging sequences to measure blood flow, 11 vessels with diameters of 4 to 7 mm were imaged in seven dogs. The flow in either the superior mesenteric vein or the inferior vena cava was measured first at laparotomy (in ml/min) with electromagnetic flow meters. Immediately thereafter, these vessels were imaged by MR in 25-mm thick sections by using a standard spin echo (SE) 750/30 sequence with a Philips 0.5-T imager. Previous phase-flow calibration of the imager and sequence allowed calculation of the blood flow rates from the phase images that were used to measure the vessels' cross-sectional areas and blood phase values. Comparison of the measurements obtained with each technique showed a significant correlation (r = .977, p less than .05) between MR-imaging values and flow-meter measurements when the blood velocity was less than approximately 40 cm/sec, the known upper limit of the flow dynamic range for the MR hardware and sequence used. There was no correlation for blood velocities greater than 40 cm/sec. However, the range of blood flow velocities in dogs and man extends to more than 100 cm/sec. Thus, these results suggest that this technique might yield valuable adjunctive flow data in routine clinical imaging provided that improvements in hardware and software permit a larger dynamic range.

Twenty-four patients with carcinoma of the uterine cervix examined by lymphangiography followed by computed tomography (CT) were reviewed to assess the findings and their impact on management. The lymphangiogram was of value in detecting metastases in relatively small nodes, (less than 1.5 cm maximum diameter) and in differentiating metastases from reactive hyperplasia in the larger lymph nodes which were opacified. Although as yet unable to define alterations in the internal architecture of lymph nodes. CT detected masses of lymph nodes totally replaced by neoplasm or those not visualized by lymphangiography. In addition, the local extension of the primary neoplasm and distant metastases, such as to the urinary tract, liver, and skeleton, were readily demonstrated by CT. In advanced or recurrent disease, CT provided new information on 10 of 17 patients but resulted in a change in management for only one.

The computed tomographic findings of four patients with neoplastic disease of the global rim are discussed. All four patients demonstrated eccentric thickening of the scleraluveal rim with extension into the globe. Possible ways of differentiating these lesions from other orbital conditions are discussed. Window widths below 100 EMI units are best to visualize neoplasms of the global rim. For evaluation of the orbits, multiple window widths with varying window levels should be used.

Pulsed Doppler sonography and liver panangiography were performed in 43 patients with cirrhosis. Fourteen patients were evaluated preoperatively, and 28 patients were evaluated after a variceal decompressive shunt. One patient was studied before and after undergoing a shunt. The direction of portal blood flow by Doppler sonography was compared with both the grading pattern and direction of flow by angiography. When portal blood flow was determined to be antegrade by Doppler sonography, angiography showed antegrade flow in 84% (grade I, II, or III portal venous pattern). Six percent had retrograde flow (grade IV), and 10% had portal vein thrombosis. When the portal blood flow was determined to be retrograde by Doppler sonography, angiography showed retrograde flow (grade IV portal venous pattern) in 80% and antegrade flow (grade I, II, or III) in 20%. When an inadequate Doppler tracing was obtained from the portal vein, angiography showed either grade I, II, or III in 38%; grade IV in 50%, and portal vein thrombosis in 13%. There was poor correlation between the calculated mean flow rates, as determined by Doppler sonography, and the angiographic grade. We conclude that pulsed Doppler sonography is accurate in determining the direction of portal flow when an adequate tracing is obtained (36 of 44 studies). When an inadequate tracing is obtained, retrograde portal flow or portal vein thrombosis is likely.

Ascites, hepatomegaly, and abdominal pain constitute the classic triad of the Budd-Chiari syndrome of hepatic-vein or inferior-vena-cava obstruction. This condition was first mentioned by Budd in the mid 1800s and additional information was provided by Chiari in the 1890s. In nearly two-thirds of patients the exact etiology cannot be determined. The syndrome has, however, been associated with hypercoagulable states, neoplasms, trauma, medications, and congenital abnormalities. The diagnosis is difficult to make clinically; therefore, radiology plays a critical role in the workup of these patients. Nuclear medicine, sonography, CT, angiography, and MRI all provide valuable diagnostic information. These data combined with hepatic biopsy determine which patients should be treated by percutaneous angioplasty or surgery, and also determine the type of shunt to be performed (such as the mesoatrial shunt when the inferior vena cava is occluded or severely compressed). Noninvasive imaging is also useful in the follow-up of patients after both percutaneous angioplasty and surgery.

The presence of ascites has been considered a contraindication to percutaneous biopsy of the liver. To determine the validity of this assumption, we performed percutaneous biopsies of the liver under CT or sonographic guidance in 28 patients who had ascites and in 28 patients who did not have ascites and compared the complication rates in the two groups. Twenty-two patients (79%) in the group with ascites and 19 patients (68%) in the group without ascites had biopsies to determine the cause or extent of chronic liver disease. The remainder were oncologic patients who had biopsies to determine the cause of a focal hepatic mass. The complication rate in the patients who had ascites (32%) was less than that in the patients who did not have ascites (43%) (the difference did not reach statistical significance, p less than .30). In the ascites group, complications included transient hypotension (five patients), a mild-to-moderate fall in hematocrit (three patients), and a small leak of ascites from the biopsy site (one patient). In the control group, minor complications included transient hypotension (three patients), a mild-to-moderate fall in hematocrit (seven patients), and a small subcapsular hematoma (one patient). One major complication occurred in the control group: a patient required a blood transfusion because of the fall in his hematocrit. We conclude that the complication rate in liver biopsies guided by CT or sonography in the presence of ascites is not higher than similar biopsies done in the absence of ascites. Ascites should not be considered a contraindication for performing such biopsies.

Clinical staging by computed tomography (CT) and lymphangiography was compared in 27 patients with pathologically staged testicular carcinoma, primarily nonseminomatous tumors. The overall accuracy of CT was 89%; the sensitivity, 90%; and the specificity, 83%. The accuracy of lymphangiography for detecting nodal abnormalities was 70%; the sensitivity, 71%; and the specificity, 67%. In 48% of cases, CT provided better delineation of tumor margins. Also, CT detected retrocrural nodal enlargement in 14% of patients and hepatic metastasis in 5%. The usefulness and limitations of both methods are discussed along with their clinical implications.

The construction of a mesoatrial shunt for portal decompression is one of the surgical procedures used for the treatment of Budd-Chiari syndrome. The results of the imaging procedures performed in eight patients treated in this fashion were retrospectively analyzed. All of the patients had angiography; seven had MR imaging and two had Doppler sonography. The demonstration of shunt patency, stenosis, or occlusion by MR and Doppler sonography was confirmed by angiography in all cases. We conclude that MR imaging may serve as an accurate screening method to assess shunt patency and to determine which patients require angiography to obtain hemodynamic data. Doppler sonography may also be a useful screening method, but additional data must be obtained to assess its role in evaluation of shunt patency.

The CT findings in 14 patients who underwent hepatic or renal embolizations are presented. In 11 patients who had postinfarction CT studies, linear, branching air collections were noted within the embolized tumor. In two patients the amount of air increased on later CT studies. This configuration of air suggested an abscess, but in no case was an abscess encountered. This air was located distal to the high density embolization material in four cases. In four cases the infarcted organ appeared denser due to "trapped contrast." The seven embolized livers did not change in size on follow-up examinations, while three renal tumors demonstrated variable size changes after embolization.

Real-time sonography was performed on 94 patients the day before and at 24 and 48 hr after extracorporeal shock-wave lithotripsy (ESWL) therapy. The ability of sonography to detect renal stones before ESWL, changes in the calculi after ESWL, and the occurrence of pre- and post-ESWL hydronephrosis was evaluated. Abdominal radiographs and linear renal tomography were used as the standard of comparison. Six other patients had sonography only either before or after ESWL. One hundred patients had a total 105 kidneys treated; 18 kidneys with more than three stones were not included. The other 87 kidneys had 102 stones evaluated by sonography before having ESWL; 66 stones (65%) were identified and 36 were not. Of those calculi not seen, 10 were less than or equal to 5 mm in diameter. Nineteen of the other 26 stones were in the ureter or at the ureteropelvic junction. Comparison of sonograms of 80 kidneys obtained before and after ESWL revealed no change in 37 (46%), more stones or fragments detected in 23 (29%), fewer stones or a change in location in 12 (15%), and an apparent decrease in the size of the original stone in eight (10%). Hydronephrosis was detected by pre-ESWL sonography in 16 kidneys (20%) and was noted to develop after ESWL in 20 (31%) of the 64 other kidneys. These results indicate that the ability of sonography to detect renal calculi is related not only to stone size but also to location. The clinical significance of pre- and post-ESWL hydronephrosis found by sonography must be considered in conjunction with the patient's symptoms, laboratory data, and other radiographic studies. Therefore, the routine use of sonography in the post-ESWL patient does not seem warranted.

Percutaneous biopsies are the most frequent interventional radiographic procedure. Their increased use is related to new imaging techniques facilitating needle placement, greater safety of small needles, and advances in cytology. Many commonly biopsied sites could not be biopsied 10 years ago. Percutaneous biopsies can be performed with both safety and accuracy. Accuracy rates vary among institutions and according to the organ biopsied, but in general they depend on operator expertise, patient cooperation, number of samples obtained, and close cooperation of the pathologist. The contribution of percutaneous biopsies to more efficient diagnosis and treatment planning indicates they will be used increasingly in the future. The yield and risks of percutaneous biopsy are reviewed, and technical considerations in applications to specific sites are discussed.

Five patients with sonographic evidence of a dilated renal vein are described. The etiology of the dilated renal vein was tumor thrombus in two patients, neoplastic arteriovenous shunting in two, and portal systemic shunting into the left renal vein in one. Tumor thrombus had echogenic enlargement of the renal vein, whereas anechoic enlargement of the renal vein was secondary to increased blood flow within the renal vein. Portorenal shunting can be differentiated from a neoplastic renal arteriovenous fistula by the presence of thrombus within the portal system and the absence of a renal mass. Pitfalls in the diagnosis of renal vein enlargement are discussed.

The sonographic findings in four patients with gynecomastia are presented. The sonographic appearance is correlated with previously described pathologic and x-ray mammographic findings. Sonographically, early, focal gynecomastia appears as a triangular, hypoechoic mass in the retroareolar area. As gynecomastia become diffuse, it results in a hyperechoic increase in the glandular parenchyma. Awareness of the various etiologies and variations in appearance is important for the sonographic diagnosis of gynecomastia.