Usefulness of Dual-Echo in Steady State(DESS) Image in Chondromalacia of Knee Joint: Comparison of DESS and Turbo Spin-Echo MR Images

ABSTRACT

PURPOSE: To evaluate the usefulness of Dual Echo in State(DESS) image in the diagnosis of chondromalacia of the knee compared with turbo spin-echo MR images. MATERIALS AND METHODS: We included 26 patients with chondromalacia of the knee. MR imaging was obtained with a 1.5T imager. Sagittal and coronal double echo T2 weighted images(TR/TE 3000~4200/16-96msec, FOV 140-160140-160mm, matrix size 180256, slice thickness 4.0mm, interslice gap 0.5mm), and sagittal DESS image(TR/TE 25.4/9.0msec, flip angle 35-45, FOV 150-160150-160mm, matrix size 192256, effective slice thickness 1.5mm) were obtained. Cartilage lesions were staged according to a modified scheme proposed by Outerbridge grade 0, normal; grade 1, softening or/and we swelling; grade 2, mild surface fibrillation or/and less than 50% of cartilage thickness; grade 3, severe surface fibrillation or/and loss of more than 50% of cartilage thickness but without exposure of subchondral bone; and grade 4, complete loss of cartilage with subchondral bone exposure. Gradings were determined by two readers with consensus, and patellofemoral, medial and lateral tibiofemoral compartments were evaluated. RESULTS: Arthroscopic findings revealed grade 1 in seven cases, grade 2 in 21 cases, grade 3 in six cases, and grade 4 in 18 cases. Sensitivity of turbo spin-echo MR images was as follows 0%, 14%, 0%, 61% in each grade, and sensitivity of DESS image was as follows; 0%, 33%, 50%, 67% in each grade(p=0.001). In the detection of chondromalacic lesions regardless of gradings, sensitivity, specificity and accuracy of conventional MR image were 59.6%, 88.6%, 78.8% and of DESS image,73.1%, 88.4%, 82.2%(p=0.007). CONCLUSION: For chondromalacia of knee joints, DESS images showed higher sensitivity than turbo spinehco MR images. Therefore, DESS images will be helpful for diagnosis of chondromalacia of knee joints.