Local area cartilage segmentation: a semiautomated novel method of measuring cartilage loss in knee osteoarthritis.

OBJECTIVE: To assess the responsiveness and reader time of a novel semiautomated tool to detect knee cartilage loss over 2 years in subjects with knee osteoarthritis. METHODS: A total of 122 subjects from the Osteoarthritis Initiative progression cohort were selected. A reader used the software method to segment cartilage on double-echo steady-state sequence scans in the medial compartment of the femur from the baseline and 24-month visits. Change in cartilage volume (ΔV) was measured at a fixed weight-bearing (WB) location with respect to the 3-dimensional coordinate system based on cylindrical coordinates. Change was measured for 5 regions of varying WB surface area centered on the fixed point. The average change (ΔV), the SD of ΔV, and the standardized response mean (SRM) are reported. RESULTS: The SRM was −0.52 for the largest region and decreased in magnitude as smaller regions of cartilage were probed. The average evaluation time was <20 minutes per knee compartment, split approximately evenly between a technician and a trained reader. CONCLUSION: The results establish that measurement of cartilage loss in a local region can be done efficiently and that the resultant measures are responsive to loss of cartilage over time. The coordinate system can potentially be used to objectively examine and establish a consistent location for all knees that is most responsive to change in cartilage volume. This technique can provide rapidly an objective quantitative measure of cartilage loss and could substantially reduce study costs for large trials and data sets.

Magnetic resonance imaging of articular cartilage abnormalities of the far posterior femoral condyle of the knee.

BACKGROUND: Incidental articular cartilage lesions of the far posterior femoral condyle (FPFC) are commonly detected. Whether or not these cartilage lesions are symptomatic or clinically significant is unknown. PURPOSE: To characterize and assess prevalence of articular cartilage abnormalities of the FPFC and associated bone marrow edema (BME) and/or internal derangements through magnetic resonance (MR) images. MATERIAL AND METHODS: 654 knee MR examinations were reviewed retrospectively. Sagittal fast spin-echo proton density-weighted images with and without fat suppression were acquired with a 1.5T scanner, and were evaluated by two readers by consensus. The following factors were assessed: 1) the prevalence of cartilage abnormalities, 2) laterality, 3) the type of cartilage abnormalities, 4) cartilage abnormality grading, 5) associated BME, 6) complications such as meniscal injury and cruciate ligament injury, and 7) knee alignment (femorotibial angle [FTA]). RESULTS: Articular cartilage abnormalities of the FPFC were demonstrated in 157 of the 654 patients (24%). Of these, 40 patients demonstrated medial and lateral FPFC cartilage abnormalities and were thus counted as 80 cases. Focal lateral FPFC abnormalities were demonstrated in 117 of 197 cases (59.4%), while diffuse lateral FPFC abnormalities were demonstrated in 24 of 197 cases (12.2%). Focal medial FPFC abnormalities were demonstrated in 23 of 197 cases (11.6%), while diffuse medial FPFC abnormalities were demonstrated in 33 of 197 cases (16.8%). No statistically significant pattern of associated BME, FTA, or internal derangements including meniscal and cruciate ligament injury was demonstrated. CONCLUSION: Articular cartilage abnormalities of the FPFC are common and were demonstrated in 24% of patients or 30% of cases. Lateral FPFC abnormalities occur 2.5 times more frequently than medial FPFC abnormalities and were more frequently focal compared with medial cohorts. BME is associated in 36.5% of cases.