Background MRI is increasingly used in clinical trials of rheumatoid arthritis (RA) because of its broader diagnostic scope and superior sensitivity to change [1-3]. Most trials thus far have used circumferential wrist coils or 5-inch surface coils to maximize resolution and signal-to-noise ratio (SNR). However, because of the coil limited effective field of view (FOV), separate scans are required to cover the hand and wrist adequately. This increases imaging time and interferes with registration of images acquired before and after contrast enhancement. In this study we present a single-FOV MRI technique developed for use with widely available circumferential knee coils allowing full-coverage of the hand and wrist with image quality comparable to that attained with surface coils.
Methods Images of one hand/wrist were acquired in 3 subjects: a healthy volunteer, a subject with PsA, and one with RA. Images were acquired using a GE 1.5T scanner with V.15 LX and an 8-channel Invivo knee coil or GE 5-inch surface coil. Slice thickness was 3mm for the STIR and 1.5mm for T1-weighted 3D gradient echo with fat suppression (3D SPGR). The hand and wrist were scanned separately when using the surface coil, but scanned together in a single acquisition with the knee coil. Image SNR was measured as mean signal in regions of muscle divided by SD of signal in air.
Results The knee coil showed two- to threefold SNR increases for the full-coverage images over the regional images produced with the surface coil, with similar depiction of erosion (figure). Total imaging time required for STIR and 3D SPGR ± contrast enhancement would be approximately 30-40 minutes with the knee coil and 45-55 minutes with the surface coil, including localizer scans, surface coil repositioning and IV injection, but not subject set-up, which may add another 10-15 minutes.
Conclusions The large-FOV protocol provides high-quality images of the hand/wrist with a knee coil in less time than with a comparable surface coil protocol. Extended-coverage MRI is especially helpful for quantifying synovitis using dynamic contrast enhanced MRI and for assessing psoriatic arthritis, which requires coverage of the distal interphalangeal joints. Knee coils are widely available and easy to use, but field tests of this technique in multi-center clinical trials have yet to be reported.
Peterfy C, et al. J Rheumatol 2011 Sep;38(9):2023-30.
Cohen, et al. Arthritis Rheum 2008; 58:1299-1309.
Genovese, et al. Arthritis Rheum 2011; 63:337-45.
Disclosure of Interest J. DiCarlo Consultant for: Abbott, Amgen, AstraZeneca, BioClinica, Biogen-Idec, Bristol-Myers Squibb, Celgene, Centocor, Crescendo, Eli Lilly and Company, Genentech, Genzyme, Icon Medical Imaging, Merck, Novartis, Perceptive Informatics, Rigel, Roche, Samsung, UCB, Pfizer, and Wyeth., Employee of: Spire Sciences, LLC, B. Hargreaves Grant/Research support from: GE Medical Systems, K. Butts Pauly: None Declared, J. Basilio Employee of: Spire Sciences, LLC, P. Countryman Employee of: Spire Sciences, LLC, C. Peterfy Shareholder of: Spire Sciences, LLC, Consultant for: Abbott, Amgen, AstraZeneca, BioClinica, Biogen-Idec, Bristol-Myers Squibb, Celgene, Centocor, Crescendo, Eli Lilly and Company, Genentech, Genzyme, Icon Medical Imaging, Merck, Novartis, Perceptive Informatics, Rigel, Roche, Samsung, UCB, Pfizer, and Wyeth., Employee of: Spire Sciences, LLC
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