Bone Signal Abnormality, as seen on Knee Joint MRI: Relationship between Its Location and Associated Injury

PURPOSE: The purpose of the study was to evaluate the relationship between the location of bone signalabnormality and associated injury, as seen on MR, in patients with acute knee joint injury. MATERIALS AND METHODS: Thirty-six patients with acute knee injury and bone signal abnormalities on MR were included in this study. Thefemur and tibia were each divided into six compartments, namely the anteromedial, medial, posteromedial,anterolateral, lateral, and posterolateral ; these were obtained in each knee joint. We evaluated the location ofbone signal abnormality and the corresponding arthroscopic or operative findings of injury to ligaments andmenisci. Cases with signal abnormalities involving more than three compartments were excluded. RESULT: Bonesignal abnormalities were demonstrated in 51 compartments. Most(84%, 43/51) were noted in the lateral half of theknee joint, the most common location being the tibio- posterolateral compartment(13/51). The femoro-lateral(11/51) and tibio- anterolateral compartment(8/51) were the next most common locations. All cases(13/13)with bone signal abnormality in the tibio- posterolateral compartment had tears at the anterior cruciate ligament,while 9 of 11 cases(81%) with abnormality in the femoro- lateral compartment had tears at the anterior cruciateligament. Six of eight cases(75%) with signal abnormality in the tibio- anterolateral compartment had tears at theposterior cruciate ligament ; 31 of 43 cases (72%) with abnormality in the lateral half of the knee joint hadtears at the medial collateral ligament. Six of eight cases(75%) with signal abnormality in the medial half of theknee joint had tears at the medial meniscus, but no lateral meniscal tear was found. Among patients with signalabnormality in the lateral half of the knee joint, the tear was lateral meniscal in nine of 43 cases(21%) andmedial meniscal in six of 43(14%). CONCLUSION: The location of bone signal abnormality, as seen on knee MR, inpatients with acute knee joint injury could be an important finding suggesting associated injury.

Differential Diagnosis of Tuberculous Pleural Effusion and Malignant Pleural Effusion: CT Accuracy and Findings

PURPOSE: To evaluate the diagnostic accuracy of CT in the differential diagnosis of tuberculous and malignant pleural effusion whether or not lung lesions are present, and to investigate the CT findings used for this differential diagnosis. MATERIALS AND METHODS: This study involved 30 patients with tuberculous pleural effusion (mean age, 44.6 years; M:F=19:11) and 20 with malignant pleural effusion (mean age, 57.2 years; M:F=10:10). All 50 patients underwent enhanced CT chest scans, and the respective conditions were pathologically confirmed. Two radiologists unaware of the pathologic results and distribution of patients reviewed these scans retrospectively and independently. They recorded the presence or absence of helpful lung lesions, CT findings of pleural effusions, their diagnoses, and the degree of confidence of their diagnoses. RESULTS: Among the total of 100 answeres, helpful long lesions were found in 57 cases. Fifty-three of 57 diagnoses (93%) were correct and 26 cases (46%) were diagnosed with a high degree of confidence. Thirty-two of 43 cases (74%) without helpful lung lesions were correct and 11(26%) were diagnosed with a high degree of confidence. All diagnoses made with a high degree of confidence were correct, even in cases without helpful lung lesions. Frequent CT findings in tuberculous pleural effusion included diffuse pleural thickening, enhancement of pleura, deposition of extrapleural fat, and pleural calcification; in malignant pleural effusion, nodular pleural thickening, pleural thickening over 1cm and associated lymphadenopathy were frequent. Mediastinal and circumferential pleural, as well as fissural involvement, were seen in both effusions; there were no statistical differences. CONCLUSION: In most cases, CT provided correct differential diagnosis between tuberculous and malignant pleural effusion. It can help determine the nature of associated lung and pleural lesions, and specific findings of the latter, and can accurately differentiate tuberculous and malignant pleural effusion.