Direct shoulder magnetic resonance arthrography for superior labral anterior-to-posterior (SLAP) and Bankart lesions: investigation into the appropriate dose and level of local anesthesia

To compare contrast leakage, pain score, image quality and diagnostic performance at different doses and levels of local anaesthesia for direct shoulder magnetic resonance arthrography. Patients (n = 157) were prospectively enrolled and allocated to Group 1 (no local anaesthetic), Group 2 (local anaesthesia to subcutaneous fat level; lidocaine 1-2 ml), Group 3 (to deltoid muscle level; 3-5 ml), or Group 4 (to subscapularis muscle level; 6-8 ml). We evaluated the frequency of contrast leakage, periprocedural/postprocedural pain, contrast-to-noise ratio of the intra-articular signal, and subjective image noise/image sharpness. Radiological diagnoses of superior anterior-to-posterior (SLAP) and Bankart lesions were assessed. All data were analysed by one-way analysis of variance/Kruskal-Wall, Χ /Fisher's exact and DeLong's tests. The frequency of contrast leakage from the injection path and subjective image noise were significantly lower in Groups 1 and 2 than in Groups 3 and 4 (p = 0.001-0.04). Periprocedural/postprocedural pain scores among Groups 2-4 were similar and lower than those of Group 1. The contrast-to-noise ratio (p = 0.11-0.97) and image sharpness (p = 0.12-0.43) were similar among Groups 2-4 and significantly lower than those of Group 1 (p = 0.001-0.02). The diagnostic performance for the assessment of superior anterior-to-posterior and Bankart lesions was better in Groups 2-4 than in Group 1, although there were no significant differences (p = 0.23-0.99). Local anaesthesia with 1-2 ml lidocaine at subcutaneous fat level reduced pain and provided optimal image quality in direct shoulder magnetic resonance arthrography. Advances in knowledge: This method can increase image quality, reduce periprocedural/postprocedural pain and potentially reduce the need for re-examination.