3T MRI Versus MR Arthrogram in SLAP Lesions

Purpose: The purpose of this study is to evaluate the diagnostic performance of three Tesla magnetic resonance imaging (3T MRI) compared to magnetic resonance arthrogram (MR arthrogram) in superior labrum anterior posterior (SLAP) lesions.

Specific aims: 1) Determine the diagnostic performance of 3T MRI in SLAP lesions utilizing arthroscopy as the gold standard (2) Determine the diagnostic performance of MR arthrogram in SLAP lesions utilizing arthroscopy as the gold standard (3) Compare the diagnostic performance of 3T MRI and MR arthrogram in SLAP lesions in a non-inferiority trial

Rationale: SLAP lesions are difficult to diagnose, even with advanced imaging (1). MRI and MR arthrogram are imaging modalities used to diagnose SLAP lesions while arthroscopy is the gold standard for diagnosing SLAP lesions. Recent study indicates that 1.5T MRI is not suitable for diagnosing SLAP lesions due to low specificity (2). The sensitivity and specificity of MRI have been reported between 66-98% and 75-91%, respectively (3,4). The reported sensitivity and specificity of MR arthrogram is generally higher at 82-100% and 58-98%, respectively (5-8). However, because the MR arthrogram is an invasive diagnostic tool, both MR arthrogram and MRI are considered standards of practice in the evaluation of SLAP lesions. To the investigators' knowledge, no previous study of SLAP lesions has evaluated the performance of 3T MRI, which has better diagnostic capabilities compared to 1.5T MRI, and compared it to MR arthrogram.

Significance: By comparing the performance of the 3T MRI and MR arthrogram in diagnosing SLAP lesions, the investigators will be able to make important diagnostic recommendations. For example, if 3T MRI is non-inferior to MR arthrogram, then the discomfort, potential harm of contrast agents, and extra resources required for MR arthrogram could be avoided with a 3T MRI.

Subjects: Inclusion criteria are patients suspected to have a SLAP lesion, either in isolation or in combination with other shoulder pathology, on history and physical examination by a fellowship trained shoulder and elbow surgeon or fellowship trained sports surgeon. Furthermore, patients must be indicated for arthroscopy. As part of standard of care, included patients will provide consent for arthroscopic evaluation. Exclusion criteria include skeletally immature patients, previously diagnosed SLAP lesion, previous intervention for SLAP lesion, contrast dye allergy, and implants that are contra-indicated for MRI.

Project design and protocol: All patients meeting inclusion and exclusion criteria will be evaluated prospectively. Patients eligible for participation will be identified in the clinics of two fellowship trained orthopaedic surgeons. The surgeons will obtain consent for study participation as well as shoulder arthroscopy. Patients will subsequently be referred to the Department of Radiology for 3T MRI and MR arthrogram. Consent for a shoulder MR arthrogram will be obtained and performed by a fellowship trained musculoskeletal radiologist. MRI and MR arthrogram images will be read by a fellowship trained musculoskeletal radiologist. Each patient will then undergo shoulder arthroscopy and indicated interventions by fellowship trained orthopaedic surgeons.

Data Analysis: Specific Aim 1: Sensitivity, specificity, negative predictive value, and positive predictive values will be calculated for MRI utilizing arthroscopy as the gold standard. These calculations will be made from a 2x2 Table. Specific Aim 2: Sensitivity, specificity, negative predictive value, and positive predictive values will be calculated for MR arthrography utilizing arthroscopy as the gold standard. These calculations will be made from a 2x2 Table. Specific Aim 3: Sensitivity, specificity, negative predictive value, and positive predictive values will be compared for 3T MRI and MR arthrogram. The investigators will evaluate for non-inferiority of 3T MRI to MR arthrogram Descriptive statistics for the cohort will be calculated with mean, median, and frequencies and distributions reported as appropriate.

Justification for number of subjects: Based on the reported sensitivity and specificity of MRI and MR arthrogram in the literature, the study is estimated to be adequately powered at 30 patients for a non-inferiority trial.

Tentative schedule for completing the project: The investigators estimate that approximately ten patients per month will be eligible for this study, based on the practice patterns of the orthopaedic surgeons involved in this study. An additonal month will be required for data analysis and writing the report.