Double echo steady state magnetic resonance imaging of knee articular cartilage at 3 Tesla: a pilot study for the Osteoarthritis Initiative.

BACKGROUND Quantitative magnetic resonance imaging (qMRI) may provide valuable measures of cartilage morphology in osteoarthritis (OA) but has been confined to sequences with relatively long acquisition times at 1.5 Tesla (T). OBJECTIVE To test the accuracy and precision of knee cartilage qMRI with a fast double echo, steady state (DESS) sequence with water excitation (we) at 3 T. METHODS As a pilot study for the Osteoarthritis Initiative, test-retest MR images were acquired in the knees of 19 participants with no OA to moderate degrees of clinical OA. Two double oblique coronal fast low angle shot (FLASHwe) sequences (1.5 mm slice thickness) were acquired at 3 T, and two sagittal DESSwe sequences (0.7 mm slice thickness). Double oblique coronal multiplanar reformats (MPR) were performed (1.5 mm slice thickness) from the sagittal DESSwe. Knee joint cartilage plates were quantified unpaired in random order with blinding to subject identification. RESULTS In the femorotibial joint, precision errors (root mean square coefficient of variation in % for unpaired analysis) for cartilage volume and thickness were 3.0-6.4% with coronal FLASHwe, 2.4-6.2% with coronal MPR DESSwe, and 2.3-8.2% with sagittal DESSwe. Correlation coefficients between DESSwe and FLASHwe ranged from r = 0.88 to 1.0. In the femoropatellar joint, precision errors (sagittal DESSwe) were 3.4-8.5%. CONCLUSIONS DESSwe permits accurate and precise analysis of cartilage morphology in the femorotibial joint at 3 T. Further studies are needed to examine the accuracy of DESSwe in the femoropatellar joint and its ability to characterise sensitivity to longitudinal changes in cartilage morphology.