At the Hospital for Special Surgery, FSE-XL is used routinely to visualize cartilage pathology, and to assess outcome following a therapeutic intervention. A cartilage-specific protocol has been developed that maximizes the contrast between normal and affected articular cartilage, while maintaining excellent visualization of adjacent structures.

An FSE-XL sequence with intermediate weighting (effective TE ranging between 30-36ms) is used to maximize contrast between fluid, fibrocartilage, and articular cartilage. With this TEeff, fibrocartilage appears hypointense, as do tendons and ligaments in their normal state. Articular cartilage is of intermediate signal intensity, in contrast with the high signal intensity seen in the adjacent fluid. It should be noted that fluid is relatively bright on this pulse sequence despite a modest echo time due to the magnetization transfer effect inherent to the FSE technique.

Case A:

19 year-old male with moderately severe chondromalacia of the patella. Axial (A1) and sagittal (A2) images using the cartilage-specific protocol developed at Hospital for Special Surgery show the patellar cartilage with high spatial resolution. (A3) A sagittal IR-FSE image shows high signal from fluid.

The axial image shows osteochondritis dissecans of the apex of the patella with softening and fibrillation of the cartilage. There has been overgrowth of subchondral bone due to osteochondral impaction and the fragment of bone is united and not loosened from the donor site. There is moderate incongruency of the subchondral plate. The articular cartilage over the femorotibial joint appears preserved, as is the trochlea.

Case B:

19 year-old male, post autologous cartilage transplantation for an osteochondritic lesion of the lateral femoral condyle. A sagittal image (B1) using the cartilage-specific protocol is shown. The transplant is hyperintense to the native articular cartilage, with a focal region of slight overgowth of the periosteal flap, which is partially detached.