Intracranial germinomas: correlation of imaging findings with tumor response to radiation therapy

OBJECTIVE: The purpose of this study was to correlate imaging characteristics of intracranial germinomas with response to radiation therapy. MATERIALS AND METHODS: Using tumor size at the completion of irradiation, we classified 23 patients with histologically proven germinomas in the pineal gland (n = 6), the suprasellar region (n = 7), and the basal ganglia (n = 10) into two groups: excellent response group (n = 14) and good response group (n = 9). Excellent response was defined as complete resolution or residual tumor less than 1.0 cm in diameter, and good response was defined as residual tumor of 1.0-3.0 cm in diameter. CT (n = 53) and MR (n = 32) images obtained before, during, and after radiation therapy were retrospectively analyzed with particular attention to the location, size, presence of cystic change, and CSF seeding of the tumors. RESULTS: In all 23 patients, the tumors decreased 85-100% in size at the completion of irradiation with 40-56 Gy. A significant factor in the different responses to irradiation between patients in the excellent and good response groups was cystic change of the tumor. Tumors with cystic components responded more slowly and had larger residual lesions than did tumors without cystic components (p < .01). In eight of 12 cystic tumors, the cystic portion of the tumor responded more slowly than did the solid portion and remained visible on imaging 6-12 months after irradiation. We found no significant differences between the two groups in location, size, and CSF seeding of tumors. In 12 patients with residual lesions at the completion of irradiation, the tumors proceeded to resolve after completion of treatment. CONCLUSION: In our study, tumor response to radiation therapy correlated negatively with the presence of a cystic region.     

Preoperative transarterial embolization of spinal tumor: embolization techniques and results

BACKGROUND AND PURPOSE: The techniques of preoperative embolization of hypervascular spinal tumors, which has been known to be helpful for completing tumor resection, have not been described in detail. The purpose of this study was to analyze the technique and to evaluate the safety and value of preoperative transarterial embolization of hypervascular spinal tumors. METHODS: Eighteen patients with hypervascular spinal tumors underwent transarterial embolization before surgery. The lesions were located between the upper cervical and lower lumbar spine: C1-T1 (n = 6), T5-L3 (n = 11), and L5 (n = 1); they arose intradurally in six patients and extradurally in 12. Thirty-one arteries were embolized with polyvinyl alcohol (PVA) particles (150-500 microm), and, in 18 of these, pieces of gelatin sponge were added for proximal pedicular embolization. The criteria for judging the effectiveness of embolization were completeness of tumor removal and estimated blood loss during surgery. RESULTS: Tumor embolization was total in eight patients, nearly total in seven, subtotal in one, and partial in two. There were no symptomatic complications associated with embolization. Tumors were totally removed in 17 patients and nearly totally removed in one. The average estimated blood loss during surgery was 1100 mL (range, 200-6000 mL) for all 18 patients, and 1540 mL in patients with extradural tumors. CONCLUSION: Preoperative embolization of hypervascular spinal tumors is safe and effective. It can make complete resection of a tumor possible and can make an unresectable tumor resectable. Superselection or flow control is necessary to achieve effective devascularization and to avoid complications.     

Animal model of bile duct dilatation created with minimally invasive surgery

RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate a method of producing obstruction of the common bile duct and concomitant biliary duct dilatation in an animal model. MATERIALS AND METHODS: Laparoscopic placement of a double-balloon occlusion device was used to produce common bile duct obstruction and bile duct dilatation in pigs. RESULTS: One week after the procedure, common bile duct obstruction and dilatation of the biliary tree were demonstrated with either percutaneous transhepatic cholangiography or percutaneous cholecystography. CONCLUSION: The use of this method is technically feasible and provides a useful subacute and chronic animal model of common bile duct obstruction and dilatation of the biliary tree for percutaneous interventional training and research purposes.     

Comparison of MR imaging with PET and ictal SPECT in 118 patients with intractable epilepsy.

BACKGROUND AND PURPOSE: MR imaging, PET, and ictal SPECT have been studied extensively as individual techniques in the localization of epileptogenic foci, but only a few comparative studies have been done. We evaluated the concordance rates of ictal video/EEG, MR imaging, PET, and ictal SPECT to compare the sensitivities of these imaging methods in the lateralization of epileptogenic foci. METHODS: The study included 118 consecutive patients who underwent surgery for medically intractable epilepsy and who were followed up for 12 months or more. MR imaging was compared retrospectively with ictal video/EEG, FDG-PET, ictal 99mTc-HMPAO SPECT, and invasive EEG as to their ability to localize the epileptogenic focus; the pathologic findings served as the standard of reference. RESULTS: MR imaging was concordant with video/EEG, PET, and ictal SPECT in 58%, 68%, and 58% of patients, respectively. With the pathologic diagnosis as the standard of reference, MR imaging, PET, and ictal SPECT correctly lateralized the lesion in 72%, 85%, and 73% of patients, respectively. Of the patients with good outcomes, MR imaging, PET, and ictal SPECT were correct in 77%, 86%, and 78%, respectively. In the good outcome group, MR imaging was concordant with PET and ictal SPECT in 73% and 62% of patients, respectively. Of 45 patients who underwent invasive EEG, MR imaging was concordant with the invasive study in 47%; PET in 58%; and ictal SPECT in 56%. Of 26 patients with normal MR findings, PET and ictal SPECT correctly lateralized the lesion in 80% and 55%, respectively. CONCLUSION: Overall concordance among the techniques is approximately two thirds or less in lateralizing epileptogenic foci. PET is the most sensitive, even though it provides a broad approximate nature of the epileptogenic zone, which is not adequate for precise surgical localization of epilepsy. PET and/or ictal SPECT may be used as complementary tools in cases of inconclusive lateralization with ictal video/EEG and MR imaging.     

Bone marrow edema and associated pain in early stage osteonecrosis of the femoral head: prospective study with serial MR images

PURPOSE: To determine the accuracy of magnetic resonance (MR) cholangiography for demonstration of the biliary tract and detection of biliary complications in patients who have undergone orthotopic liver transplantation. MATERIALS AND METHODS: Breath-hold half-Fourier rapid acquisition with relaxation enhancement MR cholangiography was performed in 25 patients who had undergone orthotopic liver transplantation. MR cholangiograms were prospectively and independently interpreted by two radiologists for depiction of the biliary tract and ductal anastomosis and for complications (eg, biliary dilatation, stricture, stones). MR cholangiographic findings were correlated with findings from direct cholangiography (n = 24) and surgery (n = 1). RESULTS: MR cholangiography completely demonstrated first-order intrahepatic bile ducts in 23 (92%) patients, the donor extrahepatic bile duct in 25 (100%), the recipient extrahepatic bile duct in 17 of 18 (94%), and the anastomosis in 24 (96%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of biliary dilatation and stricture were each 100%. Complete interobserver agreement occurred in the detection of biliary dilatation and stricture. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of stones were 100% for one radiologist and 86%, 100%, 96%, 100%, and 95%, respectively, for the other. Both radiologists agreed on the diagnosis of bile duct stones in six of seven cases (kappa = 0.90). CONCLUSION: MR cholangiography enables accurate depiction of the biliary tract and detection of biliary complications in patients with an orthotopic liver transplant.     

Diffusion-weighted single-shot echoplanar MR imaging for liver disease.

OBJECTIVE: The aims of this study were to determine apparent diffusion coefficients (ADCs) of the abdominal organs and liver lesions, to determine the effect of the magnitude of b values on the ADCs, and to determine whether measured ADCs of liver tumors help differentiate benign from malignant lesions. SUBJECTS AND METHODS: Six healthy volunteers and 126 patients were examined with diffusion-weighted single-shot echo-planar imaging using multiple b values (maximum, 846 sec/mm2). The ADCs of the liver, spleen, kidney, 49 malignant liver lesions (33 hepatocellular carcinomas, 15 metastatic liver tumors, and one cholangiocellular carcinoma), and 30 benign lesions (17 cysts, 12 hemangiomas, and one angiomyolipoma) were calculated. RESULTS: The ADCs of the abdominal organs and liver lesions showed smaller values when calculated with the greater maximum b values. The ADCs of the benign lesions calculated with all the b values of less than 850 sec/mm2 (2.49+/-1.39 x 10(-3) mm2/sec) were significantly (p = .0024) greater than those of the malignant lesions (1.01+/-0.38 x 10(-3) mm2/sec). When the maximum b value is 846 sec/mm2, use of a threshold ADC of 1.6 x 10(-3) mm2/sec would result in a sensitivity of 98% and a specificity of 80% for differentiation of malignant liver lesions from benign lesions. CONCLUSION. Measurement of ADC has good potential for characterizing liver lesions, but the calculated ADCs could be affected by the magnitude of the maximum b value.     

Takayasu arteritis: diagnosis with MR imaging and MR angiography in acute and chronic active stages.

Early diagnosis and treatment of Takayasu arteritis is important in prevention of serious complications. Spin-echo magnetic resonance imaging (MRI) can depict early wall thickening of the aorta and cine MRI can evaluate aortic valve function. Significant enhancement in and around the aorta and carotid arteries is observed on postcontrast MR images in acute phase Takayasu arteritis. In the chronic phase, contrast enhancement in the aortic wall stronger than in the myocardium suggests activity of the disease. Breath-hold contrast-enhanced three-dimensional MR angiography is very effective in noninvasive evaluation of luminal change of aortitis. Contrast-enhanced MRI and MR angiography have an important role in early diagnosis, activity determination, and follow-up of Takayasu arteritis. MRI and MR angiography can be utilized for initial diagnosis of Takayasu arteritis and replace catheterization angiography. J. Magn. Reson. Imaging 1999;10:751-757.     

Unusual gastric tumors: radiologic-pathologic correlation.

The overlap of radiologic findings in many gastric tumors makes differentiation difficult. However, some unusual gastric tumors have characteristic radiologic features that may suggest a specific diagnosis. At barium study, lipomas typically manifest as a smooth submucosal mass or an ulcerated lesion with a "bull's-eye" appearance that is indistinguishable from other mesenchymal tumors. At computed tomography (CT), lipomas usually manifest as well-circumscribed submucosal masses with fat attenuation. At radiology, glomus tumors appear as smooth submucosal masses with or without ulceration and may contain tiny flecks of calcification. These tumors frequently demonstrate strong enhancement on early-phase contrast material-enhanced images. At barium study, lymphangiomas may appear as smooth intramural masses that are indistinguishable from other mesenchymal tumors. At CT, they manifest as non-enhancing extramucosal masses with homogeneous low attenuation. Diffuse lesions in Brunner gland hamartoma manifest as multiple small nodules, producing a characteristic "cobblestone" appearance. Lymphomas may have typical imaging features (eg, more pronounced and homogeneous mural thickening) that can help differentiate them from adenocarcinoma. In addition, adenocarcinomas may demonstrate unusual findings such as transpyloric spread, unusually large polyps, or intratumoral calcifications. Familiarity with these radiologic features of gastric tumors can help ensure correct diagnosis and proper management.     

Colorectal mucinous carcinoma: findings on MRI

PURPOSE: The purpose of this work was to define the characteristic MR features of colorectal mucinous carcinomas and to correlate the mucin pool with the signal intensity of this tumor. METHOD: MRI of 12 cases of pathologically proven colorectal carcinoma containing mucin was evaluated. We analyzed the signal intensity of tumor on T1- and T2-weighted MR images and correlated the area of intratumoral high signal intensity on T2-weighted images with the mucinous pool on the pathologic specimens. Two radiologists independently estimated the area of high signal intensity in the tumor on T2-weighted images and one pathologist estimated the amount of mucinous pool in the pathologic specimen. RESULTS: In 9 (75%) of 12 cases, focal or diffuse high signal intensity areas were detected on T2-weighted fast spin echo images. In seven cases in which mucin pools were seen macroscopically, partial (n = 3) or diffuse high signal intensity areas were noted on the T2-weighted images. Among the five cases in which microscopic mucinous pools were detected on the pathologic slides, three cases showed no high signal foci on MR images, and in the remaining two cases, high signal intensity areas were noted as small foci. CONCLUSION: Intratumoral high signal intensity on T2-weighted fast spin echo MR images occurs in mucinous carcinomas and correlates with the mucin pools on pathologic specimens.     

CT features of systemic lupus erythematosus in patients with acute abdominal pain: emphasis on ischemic bowel disease

PURPOSE: To evaluate the computed tomographic (CT) features of systemic lupus erythematosus (SLE) in patients with acute abdominal pain. Special emphasis was placed on the analysis of ischemic bowel disease. MATERIALS AND METHODS: The authors retrospectively reviewed the images from 39 abdominal CT examinations performed in 33 patients with SLE and acute abdominal pain. Images were evaluated for bowel wall changes, mesenteric changes, fluid collection, retroperitoneal lymphadenopathy, peritoneal enhancement, and hepatomegaly as well as for changes in other abdominal organs. Ischemic bowel disease was diagnosed if at least three of the following signs were seen: bowel wall thickening, target sign, dilatation of intestinal segments, engorgement of mesenteric vessels, and increased attenuation of mesenteric fat. RESULTS: Thirty-one (79%) of the 39 examinations had CT findings diagnostic of ischemic bowel disease, including symmetric bowel wall thickening (n = 29), target sign (n = 26), and mesenteric vascular engorgement and haziness (n = 31). In 24 cases, bowel wall thickening was multifocal, with variable length, and did not appear to be confined to a single vascular territory. CONCLUSION: The most common CT finding in patients with SLE and acute abdominal pain is ischemic bowel disease. CT is useful for detecting the primary cause of gastrointestinal symptoms, planning treatment, and monitoring for infarction or perforation.