MR imaging of the knee at 0.2 and 1.5 T: Correlation with surgery

OBJECTIVE. The purpose of this study was to compare the diagnostic efficacy of low- and high-field-strength MR imagers in the diagnosis of anterior cr uciate ligament tears and meniscus tears. SUBJECTS AND METHODS. In 219 patients with suspected internal derangement o f the knee, MR imaging at 0.2 and 1.5 T was performed with similar sequence s. Only patients with surgically confirmed diagnosis (n = 90) were included in the statistical analysis. Radiologists were unaware of diagnosis and fi eld strength. Sensitivity, specificity, diagnostic accuracy, and inter- and intraobserver variability were determined. RESULTS. There was excellent correlation between the field strengths in acc uracy, sensitivity, and specificity for anterior cruciate ligament and meni scus tears. Accuracy for medial meniscus, lateral meniscus, and anterior cr uciate ligament tears was 91-93%, 88-90%, and 93-96%,respectively, at 0.2 T and 91-94%, 91-93%, and 97-98%, respectively, at 1.5 T. Inter- and intraob server variability values showed excellent correlation (kappa > 0.8). CONCLUSION, The level of diagnostic accuracy in anterior cruciate ligament tears and meniscus tears is comparable for low- and high-field-strength MR imagers.