MR Imaging of Osteosarcoma: Emphasis on Joint Involvment

PURPOSE: To evaluate MR imaging findings of joint involvement in patients with osteosarcoma MATERIALS AND METHODS: Among 166 patients with osteosarcoma treated between January 1993 and July 1998, 67(44 men and 23 women,mean age 20 years) whose tumors had invaded the epiphysis were included in this study. Those with preserved normalbone marrow signal intensity between the tumor and cortical bone were excluded. Tumors were located around theknee (n=52), the hip (n=7), the shoulder (n=5), the ankle (n=2), or the wrist (n=1). For all patients,pre-operative spin echo pre- and post-contrast enhanced MR images were obtained. In all cases, we assessed thepresence or abscence of intrasynovial mass, intraarticular disruption of cortical bone and articular cartilage,and joint effusion, and also evaluated the mass around the cruciate ligaments of the knee. All patients underwentsurgery and MR findings were correlated with the results of pathologic examinations. RESULTS: In six patients thetumor was found to involve the knee joint. Sensitivity and specificity for the intrasynovial mass (n= 6),intraarticular disruption of cortical bone and articular cartilage (n= 19), mass around the cruciate ligaments (n=7), and joint effusion (n= 12) were 83.3%, 100%, 83.3%, 33.3% and 98.4%, 78.7%, 95.6%, 83.6%, respectively, whileaccuracy for the intrasynovial mass and mass around the cruciate ligaments was 97% and 94.2% respectively. CONCLUSION: If MR imaging indicates the presence of a mass in the synovial cavity or around the cruciateligaments, this is suggestive MR findings of joint involvement.

Liposarcoma: MR Findings in the Histologic Subtypes

PURPOSE: To evaluate the MR imaging findings of liposarcomas of different histologic subtypes. MATERIALS AND METHODS: We evaluated MR images of 21 patients (5 men and 16 women, mean age, 55 years) with liposarcoma andcorrelated the findings with the results of histopathology. In the study group seven liposarcomas werewell-differentiated, seven were myxoid, three were mixed, two were pleomorphic, and one was round cell. RESULTS: On T1 -and T2 - weighted images, six of seven well-differentiated liposarcomas showed signal intensity equal tothe fat and hypointense septa, while the other showed low signal intensity on a T1 -weighted image, heterogeneoushigh signal intensity on a T2- weighted image, heterogeneous enhancement after the administration of contrastmedia and was dedifferentiate. Nine masses in seven patients with myxoid liposarcoma showed low signal intensityon T1-weighted images, six of the nine showed lace-like foci of high signal intensity. On T2 -weighted images, allmasses showed homogeneous high signal intensity. After administration of contrast media, five of seven massesshowed heterogeneous enhancement. Two of three mixed form were well-differentiated and myxoid types, and twosubtypes were separable on MR. Pleomorphic, round cell, mixed type myxoid and pleomorphic and unclassified casesshowed low signal intensity on T1-weighted images, heterogeneous high signal intensity on T2-weighted andheterogeneous enhancement. CONCLUSION: Using MR imaging, well-differentiated and myxoid liposcarcomas may bedifferentiated from other types.