MR imaging of the temporomandibular joint: Comparison between acquisitions at 7.0 Tesla using dielectric pads and 3.0 Tesla

Abstract

OBJECTIVES To qualitatively and quantitatively compare MR imaging of the temporomandibular joint (TMJ) at 7.0 T using high-permittivity dielectric pads and 3.0 T using a clinical high-resolution protocol. METHODS IRB approved study with written informed consent. 12 asymptomatic volunteers were imaged at 7.0T and 3.0T using 32-channel head coils. High-permittivity dielectric pads consisting of barium titanate in deuterated suspension were used for imaging at 7.0T. Imaging protocol consisted of oblique sagittal PDw-TSE sequences. For quantitative analysis, pixel-wise signal-to-noise ratio (SNR) maps of the TMJ were calculated. For qualitative analysis, images were evaluated by two independent readers using 5-point Likert-scales. Quantitative and qualitative results were compared using t-tests and Wilcoxon signed-rank tests, respectively. RESULTS TMJ imaging at 7.0T using high-permittivity dielectric pads was feasible in all volunteers. Quantitative analysis showed similar SNR for both field strengths (mean±SD; 7.0T, 13.02±3.92; 3.0T, 14.02±3.41; two-sample t-tests, p = 0.188). At 7.0T, qualitative analysis yielded better visibility of all anatomical subregions of the temporomandibular disc (anterior band, intermediate zone, posterior band) compared to 3.0T (Wilcoxon signed-rank tests, p<0.05, corrected for multiple comparisons). CONCLUSIONS MR imaging of the TMJ at 7.0 T using high-permittivity dielectric pads yields superior visibility of the temporomandibular disc compared to 3.0T.