The Significance of Alteration of Anterior Cruciate Ligament Axis as a Secondary Sign of Tear

PURPOSE: To assess the significance of alteration of the anterior cruciate ligament (ACL) axis as seen on magnetic resonance imaging of anterior cruciate ligament tear. MATERIALS AND METHODS: ACL angle (angle between lateral tibial plateau and ACL) and ACL-Blumensaat line angle (angle between ACL and Blumensaat line) were measured in 76 patients with ACL tear and 55 patients with normal ACL. The significance of the change in orientation of the ACL was evaluated. RESULTS: ACL angle was significantly smaller in the tear group (35.07 degrees +/- 10.34 degrees, mean+/-standard deviation) than in the normal group(54.11degrees+/-4.61degrees)(p<0.001); when cutoff value was less than 45 , sensitivity, specificity and accuracy were 85.5%, 98.2% and 90.8%, respectively. The ACL-Blumensaat line angle was significantly greater in the tear group (20.33degree+/-9.56degree) than in the normal group (2.55degree+/-4.86degree)(p<0.001). when cutoff value was more than 10degree, sensitivity, specificity and accuracy were 90.8%, 94.5%, and 92.4%, repectively. CONCLUSION: The change in orientation of the ACL was an important associated finding in cases of ACL tear. We suggest that cutoff values should be an ACL angle of less than 45 , and an ACL-Blumensaat line angle of more than10degree .

MR imaging of dural sinus thrombosis: A case report

We present a case of angiographically-confirmed transverse and sigmoid sinus thrombosis, image with MR, in a 20 year old male with a history of otitis media and maxillary sinusitis. T1-weighted image demonstrated an isosignal intensity mass with tubular-shaped low signal intensity in right transverse and sigmoid sinus. The thrombus had high signal intensity on T2-weighted image. The signal intensity of the thrombus on Gd-DTPA enhanced T1-weighted image was unusually high similar to that of transverse sinus. Although dural sinus thrombosis has a non-specific MR signal intensity, findings of MRI in this case may serve as an aid in future evaluation of venous thrombosis.

Clival chordoma: CT and MR fidings

A retrospective analysis of CT and MR findings was performed in five patients with histologically proved chordoma including one with chondroid chordoma. All tumors were mostly isodense to gray matter on unenhanced CT, and the single intensities were iso or low and high on T1 and T2-wgighted MR iages, respectively. The tumors had an increase in their density on enhanced CT and MR in four patients, but a chondroid chordoma was poorly enhanced after injection of contrast medicum on CT. Four tumors contained calcifications in CT images and two lesions showed hemorrhage in MR images. Cavernous sinus was involved in all patients, and brain stem and basilar artery were compressed by the tumors in three cases. Pituitary gland was only displaced upward in three patients. Clivus was destroyed in all cases, and sella turcica and sphenoid bone were involved in three patients. CT is better than MR in demonstrating calcifications and bone destruction. In defining the extension of tumor, MR appears to be superior to CT in evaluation of the relationship between the tumor and the surrounding structures.

CT findings of bilateral inferior vena cava:Differentiation from dilated retroperitoneal veins

We expierienced five cases of bilateral inferior vena cava for recent one year. We evaluated the CT findings of the cases and of dilated veins located in the left retroperitoneum (seven left gonadal, seven inferior mesenteric, and two left ascending lumber veins)in the viewpoints of the size, location and relation with the surrounding structures. Bilateral inferior vena cava (IVC) may be asymmetric and the left IYC may be smaller than other retroperitoneal veins with a round contour. The left lYC was located anterior to the spinal body and corresponded with contralateral vena cava in the anteroposterior plane. The gonadal vein was located anterior or anterolateral side of the psoas and always crossed the ureter. Most of the inferior mesenteric vein showed similar location to the opposite site of the vena cava in the anterolateral side of the psoas muscle, medial to the left ureter without crossing. The left ascending lumbar vein was similarly located to the left vena cava but dilated in a short segment. It is required to trace the vessel upward and downward and observe its continuity for correct differentiation. If it is impossible, some differential points suggested in the results of our study will be helpful for distinguishing them.