Search

Purpose: To evaluate prospectively the diagnostic accuracy of non-enhanced and gadolinium-enhanced magnetic resonance (MR) imaging in characterization of hepatic lesions., Materials and Methods: Fifty-five patients with benign and 52 patients with malignant focal liver lesions underwent examination at 1.5 T that comprised nonenhanced and dynamic contrast material-enhanced images. Four experienced radiologists independently read the different sets of images without and with knowledge of clinical history., Results: Receiver operating characteristic analysis showed that dynamic contrast-enhanced MR imaging added information to nonenhanced MR studies and thereby improved distinction between benign and malignant lesions (P < .05). Knowledge of clinical data further improved lesion characterization with nonenhanced and combined nonenhanced and contrast-enhanced MR imaging (P < .05)., Conclusion: Dynamic contrast-enhanced MR imaging is a useful adjunct for characterization of hepatic lesions. Knowledge of clinical history still has a decisive effect on interpretation of MR images of the liver.

Purpose: To determine whether the addition of computed tomographic (CT) angiography to CT arterial portography would improve lesion detection and heighten confidence in interpreting perfusion abnormalities., Materials and Methods: The two examinations were performed sequentially in 10 candidates for surgical resection of hepatic tumors. Arterial vascular access was obtained with bilateral punctures of the common femoral artery and selective placement of angiographic catheters in the hepatic artery and superior mesenteric artery (SMA). CT scans were obtained first during injection of contrast material into the SMA, followed by repeated imaging of the liver during injection of contrast material into the hepatic artery., Results: The procedure demonstrated, among other results, three additional lesions in two patients, a possibly nontumorous abnormality as tumorous in one, and a suspected tumorous abnormality as nontumorous in one. Suspected nontumorous abnormalities in four patients were confirmed at CT angiography., Conclusion: These preliminary data support a trial of this technique in a larger population.

Purpose: Magnetic resonance (MR) images were correlated with results of fine-needle aspiration (FNA) to determine the role of MR imaging in evaluating hepatic neoplasms treated with percutaneous ethanol ablation therapy (PEAT)., Materials and Methods: Contrast material-enhanced and unenhanced MR images were obtained in 11 patients with hepatic neoplasms before PEAT (13 studies) and at intervals after PEAT (25 studies). FNA was performed at each follow-up visit., Results: After PEAT, the MR appearance of the lesions was extremely variable. Also, the signal characteristics of most lesions did not change significantly with any sequence over time. Of eight lesions that demonstrated contrast enhancement before therapy, four demonstrated persistent enhancement and four showed loss of enhancement. Six of these lesions had no viable tumor at FNA. T2-weighted sequences most often showed mixed signal intensity regardless of T2-weighted imaging appearance before therapy., Conclusion: The MR appearance of PEAT-treated hepatic lesions is not a reliable indicator of residual or recurrent tumor.

Fifty-eight patients suspected of having focal hepatic disease were studied prior to and following the intravenous administration of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP), a hepatobiliary magnetic resonance (MR) contrast agent. Four doses (3, 5, 8, or 10 mumol/kg) of Mn-DPDP were used to test the hypothesis that Mn-DPDP-enhanced MR imaging would display enhancement in tumors of hepatocellular origin. A total of 203 lesions were evaluated. Histologic proof was available in 32 cases, and in 26 cases lesions were evaluated on the basis of characteristic imaging findings. Statistical calculations for distinction of tumors of hepatocellular origin yielded a sensitivity of 100%, a specificity of 92.0%, an accuracy of 93.6%, a positive predictive value of 75.9%, and a negative predictive value of 100%. The authors conclude that the presence and patterns of enhancement at Mn-DPDP-enhanced MR imaging permit reliable distinction between hepatocellular and nonhepatocellular tumors.

The authors retrospectively analyzed clinical records to determine the safety and complication rate of percutaneous ethanol ablation therapy with more than 10 mL of ethanol administered per session for treatment of malignant hepatic tumors. Ten patients underwent a total of 35 sessions with 10 mL or more of ethanol, and four underwent 18 sessions with 10 mL or less. No serious complications occurred with any dose. Pain and fever were the most common complications at all doses, and the higher frequency of these at larger ethanol volumes may be related to the greater degree of tumor necrosis induced by the larger volume.

Nine patients with biopsy-proved hepatocellular carcinoma underwent percutaneous ethanol ablation therapy (PEAT) with computed tomographic (CT) guidance. Twenty-five ablation sessions were performed in nine lesions ranging in size from 1.8 to 6.5 cm. Repeat biopsy was performed in seven of those nine lesions between 1 and 2 months after completion of therapy. CT scans obtained immediately after ablation demonstrated a necrotic area equal in size to the target lesion in five patients; four of those five patients have had negative findings at biopsy and are free of known disease. None of the patients with CT evidence of limited necrosis are currently free of disease. Peripheral nodularity was demonstrated after ablation in three patients at CT; none are free of disease. All four patients in whom there was no peripheral nodularity are free of known disease. Thus, CT evidence of necrosis and lack of nodularity immediately after PEAT are suggestive of absence of disease.

Ninety-six patients with known or suspected focal hepatic disease were evaluated in a multiinstitutional study of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'bis(phosphate) (DPDP) as a hepatic-specific contrast agent for magnetic resonance (MR) imaging. The patients were divided into four dose groups, receiving 3, 5, 8, or 10 mol/kg of Mn-DPDP. Half of the patients in each dose group received Mn-DPDP as an intravenous bolus (0.25 mL/sec) and the other half as an infusion (1 mL/min). Patients were evaluated with T1-weighted imaging parameters. No serious side effects were noted. In 76 patients, both Mn-DPDP-enhanced and nonenhanced T1-weighted images depicted the same number of lesions, but one additional lesion was depicted with enhanced imaging in 12 patients, two additional lesions in three patients, and three additional lesions in three patients. Enhanced, T1-weighted images depicted no more lesions than nonenhanced, T2-weighted images in 77 patients, but one more lesion was depicted in nine patients, two more lesions in two patients, three more lesions in one patient, and four more lesions in one patient.

Fifty computed tomographic (CT) arterial portography (CTAP) examinations were retrospectively reviewed to determine the prevalence of a pseudolesion, defined as a focal low-attenuation area located in the medial segment of the left hepatic lobe immediately anterior to the porta hepatis. This pseudolesion was considered to be present if the described low-attenuation area was detected with CTAP but was not confirmed with one or more of the following: delayed-iodine hepatic CT (DICT), magnetic resonance (MR) imaging, surgery, and routine follow-up abdominal CT. A pseudolesion was suspected in seven of 50 (14%) cases. Correlation was made with findings at DICT in all seven cases and at MR imaging in five of the seven cases. In addition, correlation with findings at pathologic examination was made in four of the seven cases (57%). Correlation with findings on one or more follow-up abdominal CT scans was also made in three of the seven cases.

The authors evaluated the safety and efficacy of a biopsy gun for performance of image-guided percutaneous biopsy of hepatic allografts in liver transplant recipients. Two hundred fifty-two liver biopsies were performed in 58 transplant recipients over a 27-month period by using this instrument with an 18-gauge needle. Major complications occurred in two of the 252 biopsies (0.8%): One hemopneumothorax necessitated drainage with a chest tube, and one hemorrhage necessitated transfusion. No patient required surgical exploration because of a complication of the biopsy. Specimens were adequate for accurate histopathologic diagnosis in 248 of 252 procedures (98.4%). The authors conclude that image-guided percutaneous biopsy of hepatic allografts with use of the biopsy gun is a safe and accurate method of obtaining hepatic tissue from liver transplant recipients for histopathologic analysis.

The enhancement characteristics in different portions of the liver during dynamic sequential bolus computed tomography (CT) with iodinated contrast material (DSBCT) were prospectively evaluated in 75 patients by using iothalamate meglumine, iopamidol, and iohexol (25 patients received each agent). After baseline noncontrast CT was performed, DSBCT was performed with a 180-mL intravenous bolus administered at 2 mL/sec. Scanning was started 25 seconds after the bolus was initiated, by using a 3-second scan time and rapid cephalocaudal table incrementation, yielding contiguous 8-mm-thick sections at a rate of nine sections per minute. On postcontrast images, peak enhancement was 115% for iopamidol and 117% for iohexol, both of which were superior to iothalamate meglumine at 95% (P less than .05). After peaking, enhancement then decreased for all three contrast agents, although the decline was more precipitous for iothalamate meglumine. Enhancement on the more caudal sections with both iopamidol and iohexol was superior to that with iothalamate meglumine (P less than .05). The data suggest that the enhancement characteristics for the two nonionic agents may be more optimal for detection of focal hepatic lesions than the ionic agent.

The authors retrospectively studied 36 hepatic masses in 20 patients who underwent computed tomography during arterial portography (CTAP) and subsequent hepatic tumor resection. The authors used the right main and left main portal veins as landmarks for the transverse scissura, along with the hepatic veins, the gallbladder fossa, and the umbilical fissure to blindly predict the segmental location of each tumor confirmed at surgery. The right main and left main portal veins were found to be consistently near the middle sections through the liver. CTAP findings and surgical descriptions agreed on the primary segmental location of 33 of 36 focal lesions (92%) but disagreed on the extent of 11 of 36 lesions (31%). Further review of the CTAP scans of the 11 lesions revealed that the extent of the lesion was more correctly described at surgery in six masses and at CTAP in four masses; in one lesion, opposite margins of the same mass were correctly described at both surgery and CTAP. Since it may be difficult or impossible to localize deep hepatic lesions intraoperatively by means of palpation or inspection, CTAP is a helpful preoperative tool for determining the segmental location of lesions and for planning the surgical approach.

The results of computed tomographic (CT)-guided percutaneous drainage in eight patients with tubo-ovarian abscesses are reported. Seven patients (88%) recovered without surgery and required no further treatment. One patient had marked clinical improvement but still required a posterior colpotomy. No complications occurred. One patient had a recurrence of symptoms 20 months after the procedure that represented a new infection. The role of CT-guided percutaneous drainage in tubo-ovarian abscesses as well as an analysis of the technical aspects associated with a successful procedure are discussed.

Twenty-nine patients with known or suspected malignancy were studied with identical T1-weighted (spin echo [SE] and inversion recovery [IR]) and T2-weighted SE magnetic resonance (MR) imaging at 0.5 and 1.5 T to evaluate the relative sensitivities of these sequences for detecting focal hepatic lesions. At 0.5 T, 98 lesions were detected with the IR sequence, 86 with the T1-weighted SE sequence, and 96 with the T2-weighted sequence. At 1.5 T, 93 lesions were detected with the IR sequence, 70 with the T1-weighted SE sequence, and 99 with the T2-weighted sequence. Although the lack of pathologic correlation precluded establishment of true sensitivity and specificity rates, data showed that magnetic field strength resulted in no significant difference for detecting focal hepatic lesions. No single sequence was shown to be significantly superior, although the T1-weighted SE sequence at 1.5 T was significantly inferior to the other sequences for detecting focal hepatic lesions. T1-weighted SE imaging at 0.5 T was significantly inferior to T1-weighted IR and T2-weighted imaging at both magnetic field strengths for detecting focal lesions in the left lobe of the liver. The authors conclude that T1-weighted IR and T2-weighted sequences alone will result in optimal MR imaging for the detection of focal hepatic lesions at 0.5 and 1.5 T.

A prospective multiinstitutional study was performed to compare the ability of dynamic sequential contrast material-enhanced computed tomography (CT), delayed contrast material-enhanced CT, and two T1-weighted magnetic resonance (MR) sequences (spin echo and inversion recovery) to demonstrate metastatic disease in the liver and abdomen in patients with cancer. All four techniques had comparable rates of hepatic lesion detection when compared individually or when the combined CT techniques were compared with the combined MR techniques. The sensitivity to hepatic disease was 96% (27 of 28 patients) for the combined MR techniques versus 93% (26 of 28 patients) for the combined CT techniques. However, CT was statistically superior in the detection of extrahepatic disease, with significant extrahepatic findings demonstrated by CT in only 12 of 59 patients (20%). For this reason, the authors continue to recommend CT in the initial screening of patients with cancer for upper abdominal metastatic disease.

Two hundred abdominal CT and angiographic examinations were performed on 137 patients with portal hypertension. These patients were being evaluated before or after a distal splenorenal shunt. CT increased the detection of umbilical and retroperitoneal varices. Angiography better detected peripancreatic varices and cavernous transformation. Both modalities together added more information than either alone in identification of coronary and/or gastroesophageal, retrogastric, and perisplenic-mesenteric varices. This additional anatomic information helped in the patient's management pre- and postoperatively.

The ability of a T1-weighted spin-echo magnetic resonance (MR) sequence to allow differentiation of benign from malignant adrenal masses at 0.5 T was investigated in 28 patients with 35 adrenal masses. All nine lesions with an adrenal mass-liver signal intensity ratio of 0.71 or less were metastases, and all 15 with a ratio of 0.78 or more were adenomas. Eleven masses (31%)--including six adenomas, three metastases, a pheochromocytoma, and a neuroblastoma--had ratios between these values. Nine of ten masses with adrenal mass-fat intensity ratios of 0.35 or less were metastases, and all 12 with ratios of 0.42 or more were benign. Eleven masses (31%), four malignant and one benign, had ratios between these values. The ratios for two masses could not be calculated due to lack of fat. The specificity of T1-weighted MR imaging in differentiating benign from malignant adrenal masses appears similar to that reported for T2-weighted imaging. However, significant overlap occurred, as has also been reported for T2-weighted imaging. While both imaging sequences may help distinguish benign from malignant adrenal masses in some cases, biopsy is still necessary when an accurate histologic diagnosis is essential.

Thirty-nine patients with lymphoma were evaluated prospectively to determine the usefulness of Ethiodol-Oil-Emulsion-13 (EOE-13) in the detection of hepatosplenic lymphoma by computed tomography. The detection rate in the spleen increased from 8% (before EOE-13 infusion) to 92% (after EOE-13 infusion). In ten of 39 patients (25%) in this series, lymphomatous disease was recognized only on the postinfusion computed tomographic scan. The postinfusion EOE-13 study demonstrated additional visceral abnormalities in 38% of the patients. The potential usefulness, limitations, and toxicity of this hepatosplenic-specific imaging agent are discussed.

Sixty patients underwent CT scanning of the liver prior to, immediately after, and four hours after intravenous administration of 60% meglumine diatrizoate. Twenty patients received a 50 ml bolus of contrast material (14.6 g of iodine), 20 received 100 ml (29.2 g of iodine), and 20 received 200 ml (58.4 g of iodine). In each group, delayed CT scanning safely raised the inherent density of the liver significantly (increase of 14.3% using 50 ml; 23.9% using 100 ml; and 40.7% using 200 ml). Thus, delayed scanning with doses presently used in abdominal and neurological CT examinations may be helpful in detecting hepatic lesions.

The role of ultrasonography in the evaluation of 12 patients who had previously undergone nephrectomy for renal carcinoma is discussed. Ultrasonography is a useful, noninvasive means of evaluating such patients for recurrence of disease. The ultrasonographic features of retroperitoneal recurrence and a potential diagnostic pitfall of bowel loops in the renal bed are emphasized.

Three hundred and thirty-four hepatic ultrasonograms were obtained in 93 patients to evaluate the chemotherapeutic response of their metastatic lesions. Four patterns of response were noted. The ultrasonographic results were correlated with those of other diagnostic modalities and found to be extremely accurate when lesions were judged to have improved, worsened, or remained unchanged. However, a fourth type of response, a change in the initial ultrasonographic pattern, was difficult to evaluate, and its significance is discussed.

Seven patients with computed tomographic (CT) evidence of cystic hepatic lesions are presented. In these cases, CT could not reliably distinguish benign hepatic cysts from other intrahepatic and extrahepatic cystic lesions. The attenuation coefficients of simple cysts and inflammatory or neoplastic lesions were similar, and smooth margins occurred in all three of these conditions. It was not possible to visualize and differentiate lesion walls from the surrounding normal hepatic parenchyma in some cases. It is concluded that the specificity of CT in the differentiation of benign cysts and other lesions is lower in the liver than it is in other areas, such as the kidney, and that in cases of diagnostic uncertainty, biopsy should be performed.

A transhepatic computed-tomographic-guided biopsy of a right adrenal mass is described. This method is simpler to perform than the usual posterior biopsy carried out with the patient prone and is less likely to cause a complicating pneumothorax. In seven of eight patients with right adrenal masses, adrenal tissue was obtained and an accurate diagnosis was possible. No complications resulted.

To determine if magnetic resonance imaging with Gd-DTPA could be used to assess renal and hepatic perfusion and possibly function, a fast-field-echo technique was used to perform sequential imaging of the kidney and liver of five subjects. Sixteen 3-second images of the same section were obtained at 13-second intervals immediately after Gd-DTPA administration, and again at 30 or 50 minutes after injection. From these images, curves of renal and hepatic signal versus time were generated. In each case the renal signal intensity peaked within 2 minutes and decreased to 60% or less by 3.4 minutes, and 35% or less by 50 minutes. Hepatic curves peaked within 2 minutes and approached initial levels by 30 minutes. These results suggest that transit and clearance of the contrast agent can be imaged by this technique.

A review was made of 365 abdominal computed tomographic (CT) examinations in 125 patients with a histologic diagnosis of lymphoma who had undergone CT before and after therapy. Clinical correlation immediately preceding the follow-up CT examination was obtained in 100 patients. In these 100 patients, five distinct subgroups emerged: (a) reduction in extent of disease without changes in internal nodal characteristics; (b) reduction in extent of disease with change in internal nodal characteristics; (c) no change in extent of disease and no change in internal nodal characteristics; (d) no change in extent of disease but change in internal nodal characteristics; and (e) disease progression. Changes in internal nodal architecture consisted of diminished attenuation or mesenteric "stranding." A 91% correlation existed between the CT findings and the clinical course. Of those patients with a worsening clinical course, and follow-up CT studies suggesting a stable or improved response to therapy, relapse in the majority (57%) involved the central nervous system. The authors conclude that limited abdominal CT examination is satisfactory in the posttherapy follow-up of lymphoma patients.

Hepatic sonography is improved when static B scanning is combined with a real-time examination, eliminating possible "blind spots" and "pseudolesions." At present, sonography is used to augment radionuclide scanning, to detect masses, and for follow-up. Because of its versatility, sonography should replace radionuclide liver scanning as the initial diagnostic procedure in patients with liver neoplasms. However, if sonography is to retain its utility in the future when compared with computed tomography, significant improvements in equipment are needed. Two other areas in which developments might be made are: (a) data representation other than echo-amplitude, and (b) the availability of liver-specific contrast agents.

A prospective study compared the efficacy of Doppler ultrasonography (US) and magnetic resonance (MR) imaging in evaluating 38 renal allografts, with specific attention to transplant rejection. Forty-three Doppler US and 42 MR examinations were performed and interpreted. Histologic correlation was obtained from 22 biopsy or nephrectomy specimens. Clinical correlation or a response to instituted therapy was used as confirmation in the remaining allografts. Accuracy in identifying cyclosporine toxicity or acute tubular necrosis could not be evaluated because there were few such cases, with concomitant rejection in most. The ability to predict and identify presence or absence of rejection was not affected by different serum creatinine values. Doppler US was significantly superior to MR imaging in identifying allograft rejection, demonstrating a higher sensitivity (95% vs. 70%), specificity (95% vs. 73%), and accuracy (95% vs. 71%). Because of its low cost and accessibility, Doppler US should become the primary modality for renal transplant screening.

Obstruction of blood flow through the inferior vena cava and portal vein may produce venous collaterals. These include the paravertebral venous system and its communications with the ascending lumbar veins and azygous/hemiazygous system; gonadal, periureteric, and other retroperitoneal veins; abdominal wall veins; hemorrhoidal venous plexus; and the portal venous system. The anatomic location of these vessels is discussed. Computed tomography demonstrates them as round or tubular structures that are isodense when compared with other venous structures following contrast material administration. Techniques of examination and methods of differentiation of these vascular structures from other abnormalities, especially lymphadenopathy, are discussed.

Renal peripelvic extravasation is a known complication of intravenous urography in patients with acute ureteral obstruction. A case of bilateral peripelvic extravasation during arteriography is presented. Possible causes for the extravasation are discussed.

Twenty-one CT examinations were performed in 19 patients who had undergone previous nephrectomy for renal carcinoma or retroperitoneal malignancy. Nine patients were free of disease and 10 had recurrence. Findings of recurrent disease included masses in the vacant renal fossa, inability to visualize the inferior vena cava or aorta, and ipsilateral psoas muscle thickening. Possible pitfalls in diagnosis are discussed.

Forty-three patients with known primary or secondary neoplastic involvement of the liver underwent evaluation to determine the number, size, and location of focal lesions before possible tumor resection. Imaging studies included computed tomography (CT) during arterial portography (CTAP), delayed CT, and magnetic resonance (MR) imaging at various pulse sequences. Results of radiologic studies were compared with surgical and pathologic findings. In the combined group of surgical and nonsurgical patients, CTAP was significantly more sensitive (85%) than all other techniques except 1.5-T T2-weighted spin-echo imaging (64%). Combining the information from all MR pulse sequences yielded a cumulative sensitivity of 68%. Combining the information from two modalities yielded sensitivity of 96% for CTAP plus MR imaging, 85% for CTAP plus delayed CT, and 77% for delayed CT plus MR imaging. The authors conclude that when it is vital to know the precise number, size, and location of focal hepatic lesions before tumor resection, CTAP has the highest sensitivity, but MR imaging is an important adjuvant.

Computed tomographic arteriography (CTA) of the liver performed during intra-arterial infusion of contrast material improved the detection of hepatic lesions in 10 of 12 patients and was the only method that accurately determined the extent of disease in 6. This technique has significant advantages over conventional hepatic computed tomography with or without intravenous contrast enhancement, or selective hepatic angiography. It is recommended in the evaluation of selected patients, especially when there is a discrepancy between the findings obtained by other methods.

Computed tomography has become an important diagnostic modality in the preoperative staging of patients with bronchogenic carcinoma. The adrenal glands represent one of the most frequent sites of metastasis. Therefore, an isolated adrenal mass discovered on preoperative thoracoabdominal CT poses a diagnostic problem. Three hundred thirty patients with histologically proved nonsmall-cell bronchogenic carcinoma were evaluated. Thirty-two had adrenal masses without further evidence of disease in the abdomen. Eight of these 32 masses were metastases, 17 were proved adenomas, and seven did not undergo biopsy. Thus, in the patients with nonsmall-cell bronchogenic carcinoma, an isolated adrenal mass is more likely benign than metastatic, and biopsy is advocated prior to withholding potentially curative surgery.

The computed tomographic (CT) angiograms of 44 patients who were being evaluated for possible hepatic surgery were studied. All patients were imaged with CT arterial portography (CTAP), delayed CT of the liver, and magnetic resonance (MR) imaging. All CTAP studies were evaluated for a "straight line," a linear variation in contrast within the liver. Sixteen patients (36%) demonstrated the straight line sign. All 16 had a mass at the proximal portion of the defect. Nine of 16 had defects that clearly correlated with portal venous distribution seen at limited digital angiography. Fourteen of the 16 patients showed loss of the straight line sign at delayed CT and/or MR imaging of the liver. These defects are thought to be due to vascular obstruction. The straight line sign will probably be seen more frequently as CTAP is more commonly used. Recognition of the sign is important in the evaluation of primary liver carcinomas, since it signifies that the tumor may be inoperable. Also, if metastatic disease is present, it alerts the surgeon to the proximity of the portal vein to the neoplasm.

Twenty-eight patients with selective and nonselective shunts for portal hypertension were evaluated using magnetic resonance (MR) imaging. Angiographic correlation was obtained in 25 patients. MR imaging enabled the detection of a patent shunt by visualizing the "flow void" phenomenon in 21 patients. Two patients had thrombosed shunts. In these 23 patients, there was no discrepancy between the findings from MR imaging and those from angiography. In the remaining five patients, there was an area of artifact in which no signal was noted, and the shunt could not be evaluated. In all five patients who had this artifact, steel coils were noted in the area of the phenomenon. Thus, MR imaging seems to be an accurate method for detecting shunt patency in all patients with shunts except those who have had prior embolization with steel coils.

The ultrasound patterns of primary hepatocellular carcinoma are described. Three types were found: a densely echogenic mass, diffuse disease, and a mixture of the two. These three patterns correspond to the previously reported angiographic and pathological manifestations of disease. The differential diagnosis is discussed.

Twenty-five extremity soft-tissue lesions were evaluated by ultrasound (US), computed tomography (CT), and xeroradiography (XR). The lesion was detected by CT in 20 of 25 cases. In five cases, a soft-tissue tumor was not identified by CT due to small lesion size, isodensity, or the inability to distinguish scar tissue from recurrent tumor. Of the three modalities, the vascular bundle was most reliably defined by CT. In 20 of 25 cases, the lesion was detected by XR, but the size was accurately determined in only 13 cases.

The hepatic sonograms of 443 patients with lymphoma were reviewed. Of these patients, 357 had nonHodgkin lymphoma, while 86 had Hodgkin disease. Sonography was able to detect disease in 5.2% of the total patient population. Disease was found in 5.8% of Hodgkin patients and 5.0% of nonHodgkin patients. The various sonographic patterns of disease are described. Hypoechoic and diffuse disease were seen in both types of lymphoma, while target and echogenic lesions were only seen in nonHodgkin lymphoma.

The occurrence of changes in the kidneys after extracorporeal shock wave lithotripsy (ESWL) was evaluated with magnetic resonance (MR) imaging in 34 patients, utilizing T1-weighted spin-echo pulse sequences. Five of the 34 patients underwent bilateral ESWL therapy before MR imaging. Of the 39 kidneys studied, 29 (74%) showed one or more changes on MR imaging: subcapsular or perinephric fluid (n = 10), focal (n = 16) or diffuse (n = 8) loss of the corticomedullary junction (CMJ), and focal areas of increased (n = 7) or decreased (n = 3) signal intensity. The CMJ changes were more prominent with increasing numbers of shock waves administered during the procedure. These relatively subtle changes detected on MR imaging may not be apparent with other imaging techniques. The long-term clinical significance of these findings is not yet known, although no apparent serious renal pathologic condition was detected.

Fifty oncologic patients with suspected hepatic metastases were prospectively evaluated by dynamic sequential hepatic computed tomography (DSHCT) and by delayed iodine hepatic computed tomography (DICT) scanning. DICT scanning was performed 4-6 hours following administration of 60 g of intravenous iodine. Both techniques were evaluated for lesion definition relative to the adjacent hepatic parenchyma and for numbers of metastases detected. Metastases were detected by both techniques in 26 patients. Fifteen patients (58%) had lesions better defined by DICT. DICT scanning detected more metastases in seven of these 15 patients. In eight patients (31%), there was no difference between the two techniques in numbers of masses detected or lesion definition. In three cases (11%), metastases were more confidently identified on the initial or DSHCT scan. DICT scanning, as described, is useful in defining and detecting hepatic metastases, especially where there is questionable hepatic involvement or better quantification of size is necessary.