In vivo rat knee cartilage volume measurement using quantitative high resolution MRI (7 T): feasibility and reproducibility.

摘要

OBJECTIVES: to assess reliability and reproducibility of quantitative MRI (7 T) in assessing rat femoro-tibial cartilage volume. METHODS: 5 healthy rat knees were scanned in vivo using a 7 T experimental imager. Sagittal high resolution 3D Gradient Echo with fat suppression sequences were performed with a dedicated home-made 2-elements array coil. 3D MRI sets were used to perform manual segmentation of the 3 cartilage compartments (femoral groove, medial and lateral tibial plateaus) by using a tactile screen. To evaluate inter- and intra-observer reproducibilities, the segmentation procedure was done blindly by two trained observers. One observer repeated the operation twice, with a period of 10 months between both readings. RESULTS: the mean duration to manually segment all the slices covering the cartilaginous joint was 4 hours. On the one hand, the inter-observer root mean square of coefficients of variation was 9.1, 6.2, 9.6 for the femoral, medial and lateral tibial compartments respectively. On the other hand, the intra-observer reproducibility was 2.1, 3.2, 2.5 for these cartilage compartments cited above. CONCLUSION: the image quality obtained at 7 Teslas with our dedicated coil allowed segmentation of the cartilage compartments with good reproducibility. This study demonstrated that MRI is a useful technology to provide a non-invasive and reliable assessment of rat knee cartilage volume.