MRI Differential Diagnosis of Complete and Partial Tears of the Anterior Cruciate Ligament of the Knee: The Usefulness of Oblique Coronal T2-Weighted Image

PURPOSE: To assess the usefulness of T2-weighted oblique coronal MR imaging (T2OCI) in the differential diagnosis of complete and partial tears of the anterior cruciate ligament (ACL) of the knee. MATERIALS AND METHODS: Thirty-three patients with ACL tear (16 complete and 17 partial tears), comfirmed by arthroscopy, were included in this study. Conventional MR imaging and T2OCI were performed, and the findings were retrospectively reviewed by two radiologists in terms of continuity, shape, axis and internal signal intensity of the ligament. Each finding was tested if there were stastistically significant differences in its prevalence between partial and complete tears. The diagnostic accuracy of T2OCI and conventional MR imaging in the detection of partial and complete tears of the ACL were compared. RESULTS: Conventional MR imaging revealed no statistically significant finding for differential diagnosis of complete and partial ACL tears. The reliable and statistically significant (p<0.001) findings of T2OCI were complete discontinuity of the ligament in cases involving complete ACL tears (14 of 16 complete tears and 2 of 17 partial tears) and the preservation of the band form for partial ACL tears (2 of 16 complete tears and 15 of 17 partial tears). The accuracy of T2OCI and conventional MR imaging was 88% and 70%, respectively. CONCLUSION: When ACL injury is vague on conventional MR images, a modality which is more useful in the differential diagnosis of partial and complete tears of the ACL, and in predicting the site of a tear, is T2-weighted oblique coronal imaging.

Usefulness of PC Based 3D Volume Rendering Technique in the Evaluation of Suspected Aneurysm on Brain MRA

PURPOSE: To evaluate usefulness of volume rendering technique using 3D visualization software on PC in patients with suspected intracranial aneurysm on brain MRA. MATERIALS AND METHODS: We analyzed prospectively 21 patients with suspected aneurysms on the routine MIP images which were obtained 15 degree increment along axial and sagittal plane, among 135 patients in whom brain MRA was done due to stroke symptoms for recent 5 months. The locations were the anterior communicating artery (A-com) in 8 patients, the posterior communicating artery (P-com) in 3, the ICA bifurcation in 5, the MCA bifurcation in 4, and the basilar tip in one. Male to female ratio was 14:7 and mean age was 62 years. MRA source images were sent to PC through LAN, and the existence of aneurysm was evaluated with volume rendering technique using 3D visualization software on PC. The presence or absence of aneurysm on MIP and volume rendering images was decided by the consensus of two radiologists. RESULTS: We found the aneurysms with volume rendering technique, from 1 patient among 8 patients with suspected aneurysm at A-com and also 1 patient among 3 patients with suspected aneurysm at P-com on routine MIP images. Confirmative angiography and interventional procedures were done in these 2 patients. The causes for mimicking the aneurysm on MIP were flow displacement artifact in 9, normal P-com infundibulum in 2, and overlapped or narrowed vessels in 8 patients, and among them confirmative angiography was done in 2 patients. CONCLUSION: Volume rendering technique using visualization software on PC is useful to scrutinize the suspected aneurysm on routine MIP images and to avoid further invasive angiography.

Efficacy of Percutaneous Microwave Coagulation Therapy for Nodular Hepatic Tumor: A Preliminary Study

PURPOSE: Percutaneous microwave coagulation therapy (PMCT) uses a new energy source, microwave, in the treatment of solid neoplasms. We evaluated the efficacy of PMCT for nodular hepatic tumors in nine patients. MATERIALS AND METHODS: Between December 1998 and June 1999, we performed PMCT in six patients with hepatocellular carcinoma (HCC), two with one and three metastatic nodules each from colon cancer, and one with adenomatous hyperplasia. Four patients were female and five were male, and their age ranged between 44 and 71 (mean, 58.8) years. Under sonographic guidance a 14-gauge guiding needle was inserted percutaneously toward the lesion, and within it a needle electrode was precisely positioned. Microwave 2450MHz in frequency and with 60 or 80 watt emission was generated for 80~90 seconds. We evaluated the ultrasound findings obtained during the procedure, pre-PMCT and follow-up CT images, changes in tumor marker(AFP or CA19-9) levels and the results of liver function tests, and complications arising during the six-month period following PMCT. RESULTS: Immediately after microwave emission, characteristic hyperechogenicity appeared on the realtime sonogram. Two patients with HCC underwent CT before PMCT, and typical enhancement during the arterial phase and washout during the portovenous phase was observed. In one patient, two metastatic lesions from colon cancer showed delayed enhancement on pre-PMCT CT. Initial follow-up CT, performed between 1 and 4 weeks after the PMCT procedure, showed that eight lesions-including two HCCs which were highly enhanced on CT before PMCT-showed no contrast enhancement, and three others showed delayed enhancement. Two of the eight lesions which showed no contrast enhancement at initial follow-up CT were markedly decreased in size (from 2.9 and 4.0 cm to 1.0 and 2.0 cm, respectively) at subseqent follow-up 3 months and 6 months later, respectively. One of the three lesions showing delayed enhancement had increased in size from 4.1 to 5.5 cm at subsequent follow-up CT, 2 months later. Serum AFP or CA19-9 levels decreased in four of six patients (66.7%) who were followed up for 6 months. Transient elevation of aspartate aminotransferase(AST) levels were noted in all patients. PMCT-related complications included intrahepatic arterioportal shunt in two patients, pleural effusion in one, skin burn in one, intraperitoneal hemorrhage in one, and mild fever, abdominal pain and nausea in seven. No complications were serious, however. CONCLUSION: Our preliminary experiences suggest that PMCT is a safe and effective treatment modality for nodular hepatic tumors.

Contrast-Enhanced Fat-Suppression MR Imaging of Avascular Necrosis of Femoral Head

PURPOSE: To evaluate the findings and role of contrast-enhanced fat suppression MR imaging in avascular necrosis(AVN) of the femoral head. MATERIALS AND METHODS: In 15 patients with AVN of the femoral head, MR T1-weighted and T2-weighted images and contrast-enhanced fat-suppression T1-weighted images were obtained, and the findings were re-viewed. Early and advanced groups were classified on the basis of clinical findings and imaging, and the en-hancement pattern was classified as either type I, rim enhancement; type II, surrounding diffuse enhance-ment; type III, intralesional enhancement; or type IV, II + III. RESULTS: Twenty-four cases of AVN of the femoral head were detected; in nine patients, lesions were bilateral. Eight cases occurred in the early group and 16 in the advanced. All eight in the early group showed the "double line sign" on T2-weighted images, with a type-I enhancement pattern. In the advanced goup, type II(8/16) and type IV(8/16) enhancement patterns were seen. Among the cases showing the type-IV pattern, the intrale-sional enhancing area showed low signal intensity on T1-weighted images and isosignal intensity on T2 weighted in one case, and low signal intensity on T1-weighted images and high signal intensity on T2-weight-ed in the other cases. There was no difference in the extent of the disease before and after enhancement. CONCLUSION: Contrast-enhanced fat-suppression MR images may be helpful in evaluating the extent of AVN of the femoral head and predicting the histopathologic findings of the disease

Infantile Myofibromatosis of the Skull

Infantile myofibromatosis is a rare benign tumor of childhood characterized by a myofibroblastic tumor in the skin, subcutaneous tissues, bones, and, occasionally, the viscera. The tumor may be solitary or multicentric. A solitary skeletal lesion most commonly occurs in the craniofacial region. We report a case of solitary infantile myofibromatosis of the skull, confirmed by excisional biopsy.

Intrapulmonary and gastric teratoma : report of two cases

The lung and stomach are very unusual sites for teratoma. The histologic findings of intrapulmonary and gastric teratomas are not different from those arising in usual sites, such as the ovary or testis. However, preoperative diagnosis is sometimes difficult to make partly because of unusual location. We report here two cases of teratoma, one intrapulmonary teratoma and the other gastric. The intrapulmonary teratoma in our study had an endobronchial tumor growth, which rules out mediastinal teratoma. Meanwhile gastric teratomas usually present as a submucosal tumor and most cases are reported in infancy and childhood. Gastric teratoma in this study occurred in a 27-year-old man. To the best of our knowledge, this case of intrapulmonary teratoma is the eighth and the gastric teratoma is the first to be reported in Korea.

Production of Carotid Artery Aneurysm in Pigs

PURPOSE: To establish the method of constructing an experimental aneurysm model in porcine carotid artery. MATERIALS AND METHODS: Fourteen aneurysms were created in the carotid arteries of eight pigs. After paramedian incision under intravenous anesthesia, the common carotid artery and external jugular vein were separated. A portion of the latter was cut to make an aneurysmal sac and this was sutured to the side wall of the common carotid arterial wall (end to side). Within one week, an arteriogram was obtained in all pigs and color Doppler study was performed in four. Digital subtraction arteriograms were serially obtained three images/sec, and these were analyzed to determine the size of the sac and the neck, flow pattern in the aneurysm, and stenosis in the common carotid artery. RESULTS: Arteriographic findings were obtained in ten of 14 aneurysms. Six aneurysms were saccular in shape, and the mean size of the sac and neck was 16x10 mm and 5.3 mm, respectively. Four aneurysms were lobulated, and in these cases, the mean size of the sac and neck was 9x3 mm and 3.7 mm, respectively. The mean size of the proximal common carotid artery was 4.5 mm, and at the operation site, mean stenosis was 40%. CONCLUSION: In 10/14 cases (71%), we successfully established an aneurysm model in the porcine carotid artery, and believe that it is suitable for use in interventional neuroradiology experiments.

Hyperdense Dots Mimicking Microcalcifications: Mammographic Findings

PURPOSE: To differentiate fine hyperdense dots mimicking microcalcifications from true microcalcifications on mammography. SUBJECTS AND METHODS: Mammograms showing hyperdense dots in ten patients (mean age, 59 years) were evalvated. Two radiologists were asked to differentiate with the naked eye the hyperdense dots seen on tenmammograms and proven microcalcifications seen on ten mammograms. Densitometry was also performed for all lesions and the contrast index was calculated. The shape and distribution of the hyperdense dots were evaluated and enquiries were made regarding any history of breast disease and corresponding treatment. Biopsies were performed for two patients with hyperdense dots. RESULTS: Two radiologists made correct diagnoses in 19/20 cases(95%). The contrast index was 0.10-0.88 (mean 0.58) for hyperdense dots and 0.02-0.45 (mean 0.17) for truemicrocalcifications. The hyperdense dots were finer and homogeneously rounder than the microcalcifications. Distribution of the hypendense dots was more superficial in subcutaneous fat (seven cases) and subareolar area(six cases). All ten patients with hyperdense dots had history of mastitis and abscesses and had been treated byopen drainage (six cases) and/or folk remedy (four cases). In eight patients, herb patches had been attached. Biopsies of hyperdense dots did not show any microcalcification or evidence of malignancy. CONCLUSION: These hyperdense dots were seen mainly in older patients. Their characteristic density, shape, distribution and clinical history makes differential diagnosis from true microcalcifications easy and could reduce unnecessary diagnostic procedures such as surgical biopsy.

The Role of the Preoperative Portal Vein Embolization in Major Hepatectomy

PURPOSE: To assess the role of the preoperative portal vein embolization (PVE) in patients in need of major hepatectomy. MATERIALS AND METHODS: Total of 11 cases consisted of Klatskin tumor (n:6), gallbladder cancer (n=2), and hepatocellular carcinoma (n=3). After percutaneous transhepatic puncture of portal vein (right:7, left:4), the embolization of 1st order branch of right portal vein was done with Gentamicin soaked Gelfoam cubes. Radiologically, the angle between the middle hepatic vein and the inferior vena cava was measured on pre- and post-PVE CT (F/U :10 days) to evaluate the hypertrophy of the left lobe. Clinically, amount and nature of the drained bile through the PTBD tube of both lobes were analyzed in 5 patients with Klatskin tumor. The interval between PVE & operation was 10-24 days. Operative findings & the changes of postop. total bilirubin were analyzed and the complication after procedure was checked. RESULTS: There was decrease in mean angle between the middle hepatic vein and the inferior vena cava from 35.9 degree to 23.9 degree, but it was insignificant statistically (p=0.09). The embolization of right portal vein was done and there was increase in amount of drained bile from the nonembolized left lobe by 2-3 folds 8-14 days after PVE. The color and consistency between both lobes were significantly different; right lobe was darker in color and softer in consistency. Postoperative total bilirubin increased by 2-3 folds 1 to 4 days after PVE and normalized 10 to 14 days after PVE. Most of the patients had mild abdominal pain and fever after PVE and 1 patient had localized hematoma at puncture site which was subsided spontaneously. CONCLUSION: The preoperative portal vein embolization is a useful method for minimizing postoperative liver failure in patients in need of major hepatectomy.

Preliminary Reports of Pancreas Transplantation: Assessment of Post Operative Radiologic Imaging

PURPOSE: We report seven cases of pancreas transplantation, first performed in Korea, in the context of postsurgical radiologic studies. MATERIALS AND METHODS: All patients with insulin-dependent diabetes mellitus received transplants from cadevaric(n=6) or living related donor(n=1). Retrospective analysis of 27 US(including 19 Duplex US), two CT, four MRi, and three scintigraphy for these patients was made with surgico-pathological correlation in five cases. RESULT:Of the seven patients, three-month graft survival was five and one-year survival was two. One patient died of abdominal abscess following surgery. US gave the valuable informations regarding the graff swelling, vascular complication, and perigraff fluid collection. RBC bleeding scan was effective of the presence or absence and location of intestinal bleeding. CT was useful in determining the extent and severity of the pancreatitis. MRI gave a little information about functional status of the grafted pancreas. CONCLUSION: The choice of appropriate imaging modalities for postsurgical work up in patients who had pacreas transplantation depends on the clinical conditions of the patients and complications suspected. Further prospective studies appear to be necessary to eatablish the interval and modality choice for early detection of the complication.

CT Differentiation of Infiltrating Renal Cell Carcinoma and Renal Urothelial Tumor

PURPOSE: It may be difficult to differentiate renal cell carcinoma involving collecting system from renal urothelial tumor invading into renal parenchyma. The purpose of this study was to assess the differences of CT findings between two conditions. MATERIALS AND METHODS: CT findings of 5 cases of renal cell carcinoma involving the renal collecting systems and 10 cases of renal urothelial tumors invading the renal parenchyma were compared, and analyzed about the presence or absence of hydronephrosis, normal or abnormal CT nephrogram, renal contour changes due to mass and tentative diagnosis. The diagnoses were confirmed at surgery. RESULTS: Renal cell carcinoma showed hydronephrosis in only 20% and normal CT nephrogram and outward contour bulging in all cases. In contrast, renal urothelial tumor showed hydronephrosis(70%), abnormal CT nephrogram(60%), and preservation of reniform shape(100%). CONCLUSION: Renal contour changes and CT nephrogram may be useful in distinguishing both disease entities.