MRI of the knee joint with a 3-D gradient echo sequence. Equivalent to diagnostic arthroscopy?

Three-dimensional (3-D) gradient echo sequences offer the advantage of volume imaging within a few minutes scanning time and creating thin contiguous slices. An optimized sequence (FISP 3D 40) was evaluated for its potential to detect lesions of the menisci, cruciate ligaments, and articular cartilage in 80 patients compared to arthroscopy as the standard. Magnetic resonance imaging showed a sensitivity of 97.9%, a specificity of 97.3%, and an accuracy of 97.5% for meniscal lesions, and a sensitivity of 100%, a specificity of 97.1%, and an accuracy of 97.5% for lesions of the cruciate ligaments. Based upon morphological criteria normal cartilage was identified in 91.5%, but fibrillation of different depths (grades 1-3) was poorly recognized. All full-thickness defects (grade 4) were recognized. Measurement of mean signal intensity (95% confidence intervals) was more useful to discriminate normal from abnormal cartilage (grades 1-3). This method promises the capability to detect early stages of oestoarthritis in future. The present results show MRI of the knee joint with a 3-D fast imaging technique to be a noninvasive alternative to diagnostic arthroscopy.