Diagnostic accuracy of Magnetic Resonance Imaging in assessment of Meniscal and ACL tear: correlation with arthroscopy

To determine the diagnostic accuracy of magnetic resonance imaging [MRI] in injuries related to anterior cruciate ligament and menisci and compare its effectiveness with that of arthroscopy. This retrospective cross-sectional study was conducted in the department of Radiology and Medical Imaging of Dallah Hospital, Riyadh, Kingdom of Saudi Arabia from September 2012 to March 2014. Fifty four patients [including 30 men and 24 women] with internal derangement of knee referred from the orthopedic consulting clinics underwent MR imaging followed by arthroscopic evaluation. The presence of meniscal and ligamentous abnormality on the imaging was documented by two trained radiologist. Findings were later compared with arthroscopic findings. The sensitivity, specificity and accuracy of MR imaging for menisci and ACL injury were calculated: 100% sensitivity, 88.4% specificity, 90% positive predictive value, 100% negative predictive value, and 94.4% accuracy were noted for medial meniscal injury. Similarly, MR had sensitivity of 85.7%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 95%, and accuracy of 92.5% for lateral meniscal injuries. Likewise, anterior cruciate ligament had 91.6% sensitivity, 95.2% specificity, 84.6% positive predictive value, 97.5% negative predictive value, and 94.4% accuracy. MRI is extremely helpful in identifying meniscal and anterior cruciate ligaments tears. MR imaging has high negative predictive value making it better choice as screening tool compared to diagnostic arthroscopic evaluation in most patients with soft tissue trauma to knee

Diffusion weighted MR imaging of ring enhancing brain lesions

To evaluate the role of diffusion weighted imaging in differentiating the cause of ring enhancing brain lesions. Analytical, descriptive study. Department of Radiology, The Aga Khan University Hospital, Karachi, from March 2007 to July 2011. Diffusion weighted imaging [DWI] was performed on 37 patients having ring enhancing lesions on their post-contrast brain MRI scans. These lesions were characterized into neoplastic and abscess cavity on the basis of diffusion restriction. Correlation of all these findings was done with histopathology obtained in all these patients. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of DWI were calculated. Comparisons of mean ADC values of abscess and neoplastic lesions were also done using t-test. DWI had a sensitivity of 94.73%, specificity of 94.44%, positive predictive value of 94.73%, and negative predictive value of 94.44% and diagnostic accuracy of 94.5% in differentiating brain abscess from neoplastic brain lesions. Mean ADC value in central cavity and wall of neoplastic lesions and brain abscesses were calculated with significant p-value of 0.001 and 0.025 respectively. Diffusion weighted imaging is non-invasive method with high sensitivity and specificity which can help in differentiation of ring enhancing neoplastic lesions and brain abscesses. This modality should be read in conjunction with conventional imaging