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Utility of radial reformatted images created from 3T high-resolution 3D wrist MRI in evaluation of the radioulnar ligaments.1Department of Radiology, St.Luke's International Hospital, Tokyo, Japan, 2Department of Radiological Sciences, University of California, Irvine, Irvine, CA, United States, 3Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan, 4Department of Functional Joint Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan, 5Department of Orthopaedic Surgery, St.Luke's International Hospital, Toyo, Japan
Synopsis
The radioulnar ligament (RUL) has been
thought as the major stabilizer of the distal radioulnar joint (DRUJ) under
dynamic loading. A detailed depiction of the dorsal and palmar RULs on MRI is
very important. However, identification of the RULs including their ulnar
styloid attachment on MRI is very difficult on the routine coronal plane, due
to not only their small size with complexity of structures but the partial volume
effect. The purpose of this study was to investigate the value of radial-slice
MPR images sourced from 3D isotropic high-resolution MR images for the
depiction of the RULs.
Introduction
The radioulnar ligament (RUL) has been thought as the major stabilizer of the distal radioulnar joint (DRUJ) under dynamic loading (1). The dorsal RUL is important in stabilizing the DRUJ in pronation, and conversely the palmar RUL is important in supination (2). Injury of the deep RUL at the ulnar fovea and base of the ulnar styloid may result in DRUJ instability. Therefore, a detailed depiction of the dorsal and palmar RULs on MRI is very important for accurate evaluation of DRUJ instability. However, wrist MRI is arguably the most technically challenging because of the small size and complexity of wrist structures (3). The routine coronal MR plane in conventional 2D wrist MRI is taken parallel to the transverse axis of the radius. However, the ulnar styloid is rotated relative to the radius in the neutral position (4). In addition, the RULs run obliquely to the transverse axis of the radius. Therefore, identification of the RULs including their ulnar styloid attachment is more difficult on the routine coronal plane, due to the partial volume effect. The purpose of this study was to investigate the value of radial-slice MPR images sourced from 3D isotropic high-resolution MR images for the depiction of the RULs.Materials and methods
This study included 41 patients (18 men, 23 women; mean age, 51.1 ± 14.3 years; age rage, 22-75 years) with wrist pain who underwent high-resolution 3T-wrist MRI including 3D isotropic FSE imaging. All 3D images were obtained in coronal slices with isotropic fat suppressed proton density weighted images (PDWI). The following MRI sequences were reviewed for evaluation of depiction of RULs: coronal 3D fat suppressed PDWI: TR/TE 1400/60ms; voxel size, 0.35 x 0.35 x 0.35mm; gap, 0mm; FOV, 70mm; and coronal 2D fat suppressed PDWI: TR/TE 3000/30ms; voxel size, 0.23 x 0.35 x 2.0mm; gap, 2mm; FOV, 70mm. We created radial-slice MPR images centered on the midpoint of the ulnar styloid process in increments of 1 degree from the original coronal 3D isotropic images (Fig.1). Qualitative assessment related to delineation of dorsal and palmar RULs was performed by two musculoskeletal radiologists. The image quality was graded on a 0 to 4 scale; 0, no visualization; 1, poor visualization, 2, satisfactory, 3, good; and 4, excellent. Then we compared whether or not the ulnar styloid process and disc proper are depicted in a same plane simultaneously between radial-slice MPR images and conventional 2D images. The paired t-test was used to determine the significance of the differences in scores between high-resolution isotropic 3D and conventional 2D sequences.Results
Mean qualitative scores for dorsal and palmar RULs on radial-slice MPR images sourced from 3D isotropic images were significantly higher than conventional 2D images (3.9 vs 2.4 for dorsal RUL and 4.3 vs 2.6 for palmar RUL, p<0.01 respectively)(Fig.2 and 3). The rate of simultaneous depiction of the ulnar styloid process and disc proper on a same slice was 100% on radial-slice MPR images and 22% on conventional 2D images (P<0.001).Conclusions
We evaluated the usefulness of high-resolution 3D isotropic wrist MR images for depicting the radioulnar ligaments. Radial reformatted images created from 3T high-resolution 3D wrist MRI are vital for evaluation of the radioulnar ligaments, and their depiction is poor using only conventional 2D coronal images.Acknowledgements
No acknowledgement found.References
1. Kleinman WB. Stability of the distal radioulna joint: biomechanics, pathophysiology, physical diagnosis, and restoration of function what we have learned in 25 years. J Hand Surg Am. 2007;32(7):1086-106.
2. Kihara H et al. The stabilizing mechanism of the distal radioulnar joint during pronation and supination. J Hand Surg Am. 1995;20(6):930-6.
3. von Borstel D et al. High-Resolution 3T MR Imaging of the Triangular Fibrocartilage Complex. Magn Reson Med Sci. 2017;16(1):3-15.
4. Nozaki T et al. High-resolution MRI of the ulnar and radial collateral ligaments of the wrist. Acta Radiol. 2017;58(12):1493-1499.
Figures
Fig.2 The dorsal and palmar radioulnar ligaments on 2D image.
Disc proper (white arrow) and ulnar styloid process (red arrow) are not shown in the same section on 2D sequence. The delineation of the dorsal radioulnar ligament (RUL) (blue arrow) is worse than that of the palmar RUL (yellow arrow).
Fig.3 The dorsal and palmar radioulnar ligaments on radial-slice MPR image sourced from 3D isotropic image.
Disc proper (white arrow) and ulnar styloid process (red arrow) are shown in the same section on 3D sequence. The delineation of the dorsal RUL (blue arrow) and the palmar RUL (yellow arrow) are better on 3D sequence than on 2D sequence.