Optimized 3D brachial plexus MR neurography using deep learning reconstruction.

OBJECTIVE: To evaluate whether 'fast,' unilateral, brachial plexus, 3D magnetic resonance neurography (MRN) acquisitions with deep learning reconstruction (DLR) provide similar image quality to longer, 'standard' scans without DLR. MATERIALS AND METHODS: An IRB-approved prospective cohort of 30 subjects (13F; mean age = 50.3 ± 17.8y) underwent clinical brachial plexus 3.0 T MRN with 3D oblique-coronal STIR-T2-weighted-FSE. 'Standard' and 'fast' scans (time reduction = 23-48%, mean = 33%) were reconstructed without and with DLR. Evaluation of signal-to-noise ratio (SNR) and edge sharpness was performed for 4 image stacks: 'standard non-DLR,' 'standard DLR,' 'fast non-DLR,' and 'fast DLR.' Three raters qualitatively evaluated 'standard non-DLR' and 'fast DLR' for i) bulk motion (4-point scale), ii) nerve conspicuity of proximal and distal suprascapular and axillary nerves (5-point scale), and iii) nerve signal intensity, size, architecture, and presence of a mass (binary). ANOVA or Wilcoxon signed rank test compared differences. Gwet's agreement coefficient (AC2) assessed inter-rater agreement. RESULTS: Quantitative SNR and edge sharpness were superior for DLR versus non-DLR (SNR by + 4.57 to + 6.56 [p < 0.001] for 'standard' and + 4.26 to + 4.37 [p < 0.001] for 'fast;' sharpness by + 0.23 to + 0.52/pixel for 'standard' [p < 0.018] and + 0.21 to + 0.25/pixel for 'fast' [p < 0.003]) and similar between 'standard non-DLR' and 'fast DLR' (SNR: p = 0.436-1, sharpness: p = 0.067-1). Qualitatively, 'standard non-DLR' and 'fast DLR' had similar motion artifact, as well as nerve conspicuity, signal intensity, size and morphology, with high inter-rater agreement (AC2: 'standard' = 0.70-0.98, 'fast DLR' = 0.69-0.97). CONCLUSION: DLR applied to faster, 3D MRN acquisitions provides similar image quality to standard scans. A faster, DL-enabled protocol may replace currently optimized non-DL protocols.

Postoperative Lumbar Fusion Bone Morphogenic Protein-Related Epidural Cyst Formation.

Bone morphogenetic protein is broadly used in spinal surgery to enhance fusion rates. Several complications have been associated with the use of bone morphogenetic protein, including postoperative radiculitis and pronounced bone resorption/osteolysis. Bone morphogenetic protein-related epidural cyst formation may represent another complication that has not been described aside from limited case reports. In this case series, we retrospectively reviewed imaging and clinical findings of 16 patients with epidural cysts on postoperative MR imaging following lumbar fusion. In 8 patients, mass effect on the thecal sac or lumbar nerve roots was noted. Of these, 6 patients developed new postoperative lumbosacral radiculopathy. During the study period, most patients were managed conservatively, and 1 patient required revision surgery with cyst resection. Concurrent imaging findings included reactive endplate edema and vertebral bone resorption/osteolysis. Epidural cysts had characteristic findings on MR imaging in this case series and may represent an important postoperative complication in patients following bone morphogenetic protein-augmented lumbar fusion.

MRI findings of spinal accessory neuropathy.

AIM: To characterise the magnetic resonance imaging (MRI) appearance of patients with spinal accessory nerve (SAN) denervation. MATERIAL AND METHODS: Twelve patients who had SAN denervation on electromyography (EMG) were included. The sternocleidomastoid and trapezius muscles and the SAN were assessed using MRI. RESULTS: Trapezius muscle atrophy was seen in 11 (92%), and of those patients, T2/short tau inversion recovery (STIR) signal hyperintensity was also demonstrated in seven (58%). All three patients with prior neck surgery had scarring around the SAN, and one of these patients demonstrated a neuroma, which was confirmed surgically. CONCLUSION: Features of SAN neuropathy on MRI include atrophy and T2/STIR signal hyperintensity of the trapezius, and in patients who have had posterior triangle neck surgery, scarring may be seen around the nerve.