Prospective respiratory triggering improves high‐resolution brachial plexus MRI quality

Abstract

Background Oblique sagittal MRI sequences, orthogonal to the longitudinal axis of the brachial plexus, can reliably depict morphologic and signal abnormalities. However, nerve visualization may be obscured by ghosting artifact from periodic respiratory motion. Respiratory triggering (RT) with a thoracoabdominal bellows can reduce ghosting artifact, but it is not routinely used for brachial plexus MRI. Furthermore, the efficacy of prospective RT for brachial plexus imaging has not yet been reported. Purpose To compare brachial plexus MRI sequences acquired with and without respiratory triggering. Study Type Prospective. Subjects Five volunteers and 20 patients were included. Each subject was imaged with and without RT during the same session. Field Strength/Sequence Proton density or T2‐weighted Dixon fat suppressed sequences were obtained at 3.0T using receive‐only 16‐channel flexible array coils. Assessment Three musculoskeletal radiologists blindly evaluated each sequence using subjective scoring criteria for ghosting artifact, nerve conspicuity, and diagnostic confidence. Nerve conspicuity scores at three distinct plexus levels were summed to calculate an overall image quality score. Statistical Tests Marginal proportional odds logistic regression models were used to compare all scores between RT and non‐RT. Gwet's agreement coefficient was used to assess interobserver and intraobserver reliability. Results Mean scan time per sequence increased from 4:25 minutes (95% confidence interval [CI], 4:02–4:49 min) with non‐RT to 6:09 minutes (95% CI, 5:42–6:35 min) with RT. RT reduced ghosting artifact (odds ratio [OR] = 0.21, 95% CI: 0.09–0.46, P < 0.001), improved overall image quality (OR = 4.88, 95% CI: 2.18–10.95, P < 0.001), and increased diagnostic confidence (OR = 3.72, 95% CI: 1.61–8.63, P = 0.002) for all readers. Interobserver agreement for ghosting artifact and image quality was substantial to almost perfect (AC2 = 0.74–0.85). Interobserver agreement for all other scores was moderate to almost perfect (AC2 = 0.61–0.82). Intraobserver agreement was substantial to almost perfect for all parameters (AC2 = 0.76–1.0). Data Conclusion Prospective RT with bellows can effectively minimize ghosting artifact and improve image quality for brachial plexus MRI within clinically optimal acquisition times. Level of Evidence: 1 Technical Efficacy: Stage 2

Retrospective Planning Study of Patients with Superior Sulcus Tumours Comparing Pencil Beam Scanning Protons to Volumetric-Modulated Arc Therapy

“…It can enable uncertainty margins to be reduced, thus better sparing OARs [ 43 ]. However, respiratory motion can cause ghosting artefacts and compromise resolution [ 44 ]. Furthermore, although advanced MRI-to-four-dimensional computed tomography registration algorithms exist, they are not yet used in clinical practice [ 45 ] and assessment on an individual basis, in order to minimise error propagation, is recommended [ 46 ].…”

Brachial Plexus Magnetic Resonance Neurography

“…Newer techniques such as retrospective motion compensation with soft gating may also be appropriate for reducing respiratory motion artifacts without additional scan time 26 . Deep learning algorithms for MRN have been previously explored and may also play a role in reducing scan time and motion artifact in the future 11,27,28 …”

“…26 Deep learning algorithms for MRN have been previously explored and may also play a role in reducing scan time and motion artifact in the future. 11,27,28…”

Team Approach: Management of Brachial Plexus Injuries

“…1). Prospective respiratory triggering to reduce respiratory motion artifact has been shown to improve image quality on MRI 21 . Nerves are evaluated for signal hyperintensity, enlargement, and loss of fascicular architecture, the latter suggesting high-grade axonotmetic or neurotmetic injury.…”