Visualization of wrist ligaments with 3D and 2D magnetic resonance imaging at 3 Tesla

Imaging assessment of dorsal scaphoid displacement in patients with scapholunate ligament tears: what is the best option for quantitative assessment?

OBJECTIVE

To compare four different methods for the quantitative assessment of dorsal scaphoid displacement in patients with scapholunate ligament tears.

METHODS

A total of 160 consecutive patients who underwent CT arthrography to evaluate a suspected scapholunate ligament tear were prospectively included in this study approved by the local ethics committee. MR images were available for 65 of these patients. Two readers independently evaluated the dorsal scaphoid displacement on conventional radiographs with the dorsal tangential line (DTL) method, the posterior radioscaphoid angle (PRSA) on both CT and MR, and the radioscaphoid congruency ratio on MR. These measurements were compared in groups of patients with and without scapholunate ligament tears.

RESULTS

The measurement interobserver agreement was considered excellent for the DTL and the PRSA on CT (ICC = 0.93 and 0.88, respectively), good for the PRSA (ICC = 0.65) on MR, and moderate for the RSCR (ICC = 0.49). There was a significant increase in the values of DTL and PRSA on CT between patients with normal and ruptured SLIL (p < 0.0001). The same tendency was seen on MR-based methods, but these differences were only significant for one reader. The only method that allowed the differentiation between patients with normal and partially ruptured SLIL was the PRSA on CT. PRSA on CT yielded the best diagnostic performance for SLIL rupture (a sensitivity and a specificity of 70-82% and 70-72%).

CONCLUSION

DTL on standard radiographs and the PRSA on CT are the most consistent imaging indicators of SDD with an excellent interobserver reproducibility.

KEY POINTS

• Dorsal scaphoid displacement is an important prognostic factor in patients with scapholunate instability. • Quantitative assessment of dorsal scaphoid displacement can be performed on conventional radiographs and CT with an excellent reproducibility. • The posterior radioscaphoid angle on CT yielded the best diagnostic performance for the identification of scapholunate ligament tears and the only method allowing differentiation between patients with normal and partially torn ligaments.

Visualization of wrist anatomy-a comparison between 7T and 3T MRI

OBJECTIVE

Injuries to the wrist are, due to its small size and complex anatomical structures, difficult to assess by MR, and surgical interventions such as diagnostic arthroscopy are often necessary. Therefore, improved visualization using non-invasive methods could be of clinical value. As a first step of improvement, the purpose of this study was to evaluate visualization of anatomical structures at 7T compared with 3T MR.

METHODS

Eighteen healthy volunteers (three males and three females from each age decade between 20 and 49 years) were examined with 7T and 3T MR. Four musculoskeletal radiologists graded 2D and 3D images on a five-level grading scale for visibility of ligaments, cartilage, nerves, trabecular bone, and tendons, as well as overall image quality (i.e., edge sharpness, perceived tissue contrast, and presence of artefacts). Statistical analysis was done using a visual grading characteristics (VGC) analysis.

RESULTS

Visibility of cartilage, trabecular bone, tendons, nerves, and ligaments was graded significantly higher at 7T with an area under the curve (AUC_VGC) of 0.62-0.88 (95% confidence interval [CI] 0.50-0.97, p = < 0.0001-0.03) using either 2D or 3D imaging. Imaging with 3T was not graded as superior to 7T for any structure. Image quality was also significantly superior at 7T, except for artefacts, where no significant differences were found.

CONCLUSIONS

Tendons, trabecular bone, nerves, and ligaments were all significantly better visualized at 7T compared to 3T.

KEY POINTS

• MRI of the wrist at 7T with a commercially available wrist coil is feasible at similar acquisition times as for 3T MRI. • The current study showed 7T to be superior to 3T in the visualization of anatomical structures of the wrist, including ligaments, tendons, nerves, and trabecular bone. • Image quality was significantly superior at 7T, except for artefacts, where no significant differences were found.

Improved diagnostic accuracy for ulnar-sided TFCC lesions with radial reformation of 3D sequences in wrist MR arthrography

Objectives

Triangular fibrocartilage complex (TFCC) injuries frequently cause ulnar-sided wrist pain and can induce distal radioulnar joint instability. With its complex three-dimensional structure, diagnosis of TFCC lesions remains a challenging task even in MR arthrograms. The aim of this study was to assess the added diagnostic value of radial reformatting of isotropic 3D MRI datasets compared to standard planes after direct arthrography of the wrist.

Methods

Ninety-three patients underwent wrist MRI after fluoroscopy-guided multi-compartment arthrography. Two radiologists collectively analyzed two datasets of each MR arthrogram for TFCC injuries, with one set containing standard reconstructions of a 3D thin-slice sequence in axial, coronal and sagittal orientation, while the other set comprised an additional radial plane view with the rotating center positioned at the ulnar styloid. Surgical reports (whenever available) or radiological reports combined with clinical follow-up served as a standard of reference. In addition, diagnostic confidence and assessability of the central disc and ulnar-sided insertions were subjectively evaluated.

Results

Injuries of the articular disc, styloid and foveal ulnar attachment were present in 20 (23.7%), 10 (10.8%) and 9 (9.7%) patients. Additional radial planes increased diagnostic accuracy for lesions of the styloid (0.83 vs. 0.90; p = 0.016) and foveal (0.86 vs. 0.94; p = 0.039) insertion, whereas no improvement was identified for alterations of the central cartilage disc. Readers’ confidence (p < 0.001) and assessability of the ulnar-sided insertions (p < 0.001) were superior with ancillary radial reformatting.

Conclusions

Access to the radial plane view of isotropic 3D sequences in MR arthrography improves diagnostic accuracy and confidence for ulnar-sided TFCC lesions.

Key Points

• In multi-compartment arthrography of the wrist, ancillary radial plane view aids assessability of the foveal and styloid ulnar-sided insertions of the triangular fibrocartilage complex.

• Assessment of peripheral TFCC injuries is more accurate with access to radial multiplanar reconstructions.

• Additional radial planes provide greater diagnostic confidence.