José Raya MSc, Presenter: Nothing to Disclose

Annie Horng MD, Abstract Co-Author: Nothing to Disclose

Olaf Dietrich PhD, Abstract Co-Author: Nothing to Disclose

Svetlana Krasnokutsky, Abstract Co-Author: Nothing to Disclose

Luis Saura Beltran MD, Abstract Co-Author: Nothing to Disclose

Maximilian F. Reiser MD, Abstract Co-Author: Nothing to Disclose

Michael Paul Recht MD, Abstract Co-Author: Nothing to Disclose

Christian Glaser MD, Abstract Co-Author: Nothing to Disclose

To assess the potential value of in vivo DTI of articular cartilage for the early diagnosis of OA as compared with the widely used T2 relaxation time.

The patellar cartilage of 16 healthy volunteers (30.7±2.3 y, no episodes of knee pain, no history of trauma) and 10 OA-diagnosed patients (62.6±8.8 y) from the NYU-HJD cohort with subtle signal abnormalities and absence of cartilage erosion were imaged at 7T with a birdcage transmit, 28-channel receive knee coil. The MRI protocol included a high-resolution (0.5 mm isotropic) T2*-weighted FLASH sequence, a Line Scan Diffusion Imaging sequence and a multi-slice multi-echo sequence for T2 calculation both with a resolution of 0.6×0.6×2 mm2. Cartilage was segmented and maps (T2, ADC and FA) were calculated. In each slice of each volunteer, the cartilage was divided into 2 layers parallel to the bone-cartilage interface and four sectors from medial to lateral. Differences between the MRI parameters in the healthy and OA collectives were assessed with the non-parametric Wilcoxon test globally (averaged over all the slices), by layers, by sectors. ROC-curve analysis was used to assess the ability of each MRI parameter to discriminate healthy from OA patients.

Globally, ADC and FA differed significantly (P<0.05), between the OA and the healthy collective (Healthy: ADC 1.0×10-3 mm2/s, FA 0.3; OA: ADC 1.3×10-3 mm2/s, FA 0.2), but T2 no significant difference could be determined (Healthy: 23ms; OA: 22 ms). An optimal threshold of 1.2×10-3 mm2/s for ADC allowed to differentiate both populations with a specificity of 0.81 (13/16), a sensitivity of 0.90 (9/10). The same analysis for FA yielded an optimal cutoff of 0.26 (specificity=0.88 (14/16), sensitivity=0.80 (8/10)). T2 showed a low ability to differentiate (specificity=0.68 (11/16), sensitivity=0.60 (6/10)). In the two layers and the 4 sectors ADC was significantly higher and FA was significantly lower (P<0.05) in the OA population than in the healthy collective, whereas no difference could be assessed in T2.

In vivo DTI of articular cartilage provides new biomarkers for the early diagnosis of OA. In our study DTI discriminated both populations more accurately than the T2 relaxation time.

In vivo DTI of the articular cartilage is a promising proton-based MRI biomarker for the early diagnosis of OA, which does not use contrast agent and provides submilimeter anatomical resolution.

Raya, J, Horng, A, Dietrich, O, Krasnokutsky, S, Beltran, L, Reiser, M, Recht, M, Glaser, C, In Vivo DTI of the Articular Cartilage Can Discriminate OA Patients from Healthy Subjects.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034472.html