Three-dimensional ultrashort echo time (3D UTE) magnetic resonance imaging (MRI) of the normal and degenerative disco-vertebral complex at 4.7T: a feasibility study with longitudinal evaluation.

Abstract

To assess feasibility of a three-dimensional ultrashort echo time (3D-UTE)-sequence to evaluate normal and pathological disco-vertebral complex (DVC), with assessment of its different portionsin a rat model of degenerative disk disease (DDD) with histological correlation.To assess whether this sequence, in comparison with long echo time T2-weighted sequence, is able to monitor DDD with differentiation of early from chronic DVC changes in pathological mechanical conditions. Five rats were induced with DDD model by percutaneous disk trituration of the tail with an 18-G needle under US-guidance and imaged at 4.7T. MRI protocol included fat-saturated-T2 (RARE) and 3D-UTE-sequences performed at baseline (day 0. n = 5 animals /10 DVC) and each week (W) from W1 to W10 postoperatively. Visual analysis and signal intensity measurements of SNR and CNR of all DVC portions were performed on RARE and UTE images. Following killing (baseline, n = 1/2 DVC; W2, n = 2/4 DVC; W10, n = 2/4 DVC), histological analysiswas performed and compared with MRI. In normal DVC, unlike conventionalRARE-sequences, 3D-UTEallowed complete identification of DVC zonal anatomy including on visual analysis and CNRmeasurements. In pathological conditions, SNR and CNR measurements of the annulus fibrosus and nucleus pulposus on 3D-UTE distinguished early discitis at W1 fromchronic discopathy (P < 0.001 for SNR and P < 0.001 for CNR). Neither the normal complete anatomy of the DVC nor its pathological patterns could be assessed on conventional sequences. Unlike conventional sequences, 3D-UTE enables visualization of the complete normal DVC anatomy and enables monitoring of DDD differentiating between earlyDVC changes from chronic ones. Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.