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DOI: 10.1055/s-2005-931831
Comparison between 1.5 and 3 Tesla MR Imaging of the Temporo Mandibular Joint (TMJ)
Purpose: To compare TMJ imaging using a standard 1.5T protocol with a new 3.0T high resolution approach.
Methods: 15 volunteers underwent bilateral MRI of the TMJ. MRI was performed with 1.5T (standard TMJ coil) and 3.0T (purpose build phased array coil) MR system (Gyroscan Intera; Philips Medical Systems). Imaging protocols consisted of sagittal PD-TSE in open and closed mouth and coronal PD-TSE sequences in closed mouth technique. Total examination time (15min) was similar for both systems. Acquisition parameters were adjusted for 3.0T and voxel size was reduced from 0.29×0.29×3.0mm (1.5T) to 0.15×0.15×1.5mm (3.0T). Two observers assessed delineation, image quality, and artifacts in anatomical landmarks (discus, bilaminar zone, capsular attachment, cortical bone) in consensus and ranked them qualitatively on a five-point scale from 1 (optimal) to 5 (non-diagnostic). For quantitative analysis CNR-measurements were obtained between discus and retrodiscal tissue. Statistical significance was determined by Student's t- and Wilcoxon test.
Results: Discus position and mobility was identical in both exams. All anatomical landmarks had significantly higher scores at 3.0T. In particular the capsular attachments were seen better at 3.0T. Overall image quality was improved with the new protocol (1.46 vs. 2.0, p<.0001), whereas artifact score was similar (1.32 vs. 1.14 p=.132). Quantitative evaluation showed significant higher CNR for 3.0T (10.23 vs. 8.08, p<.0001).
Conclusion: Investing the higher SNR at 3.0T into better spatial resolution depiction of the normal anatomy of the TMJ benefits significantly. We anticipate that this advantage of 3.0T MRI will also permit a more detailed analysis of capsular and discus pathology.