Donald J. Flemming

High Prevalence of Pelvic and Hip Magnetic Resonance Imaging Findings in Asymptomatic Collegiate and Professional Hockey Players

Background: Prior retrospective studies have reported magnetic resonance imaging (MRI) findings of common adductor–abdominal rectus enthesopathy and acetabular labral tear in athletes treated for athletic pubalgia and hip pain. The true prevalence of these findings and association with symptoms in this population is unknown. Purpose: This study was undertaken to determine the prevalence of pelvic and hip MRI findings and association with clinical symptoms in professional and collegiate hockey players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The study included 21 professional and 18 collegiate hockey players. Self-reported symptoms were measured using a modified Oswestry Disability Questionnaire. Participants underwent 3-T MRI evaluation of the pelvis and hips. The MRI scans were interpreted independently by 3 musculoskeletal radiologists in 2 sessions separated by 3 months using a 5-point Likert scale to assess for features associated with common adductor–abdominal rectus dysfunction and hip pathology. To estimate prevalence, MRI findings rated 4 or higher on 4 of the 6 interpretations were considered positive. A variance component analysis was applied to determine intrareader and interreader reliability and the lower 95% confidence limits (CLs). Results: No participants reported symptoms related to pelvic or hip disorders. The MRI findings of common adductor–abdominal rectus dysfunction were observed in 14 of 39 participants (36%) and hip pathologic changes in 25 of 39 (64%). There was moderate agreement between readings, with intrareader and interreader reliabilities ranging from 0.37 to 1.00. The interreader reliability was less for evaluation of hip pathologic abnormalities than for groin pathologic abnormalities, with the lowest reliability observed in reporting of hip osteochondral lesions (0.37 with lower 95% CL of 0.22) and fluid in the primary cleft (0.45 with lower 95% CL of 0.29) and perfect reliability in the absence of effusion and abdominal rectus tendon tears. Overall, 30 of 39 (77%) asymptomatic hockey players demonstrated MRI findings of hip or groin pathologic abnormalities. Conclusion: Given the high prevalence of MRI findings in asymptomatic hockey players, it is necessary to cautiously interpret the significance of these findings in association with clinical presentation. Future investigations will determine whether these asymptomatic findings predict future disabilities.

Two-dimensional glenoid version measurements vary with coronal and sagittal scapular rotation.

BACKGROUND Accurate analysis of osseous glenoid morphology is important in treating glenohumeral arthritis and instability. Two-dimensional computed tomography scans are used to evaluate glenoid alignment. Accuracy of this method is dependent on the angle of axial reconstruction in relation to the position of the scapula. The purpose of this study was to investigate the effect of scapular rotation in the coronal and sagittal planes on glenoid version as measured on two-dimensional images. METHODS Computer-generated three-dimensional models of scapulae from computed tomography scans of thirty-six shoulders in whole-body cadavers were generated. The anatomic geometry of these models had been previously validated. The position of the scapulae relative to the gantry was determined. The three-dimensional models were rotated in 1 degree increments in the coronal and sagittal planes. Glenoid version was measured on two-dimensional images for each of the rotation increments. Version variability at each rotation increment was calculated. RESULTS The anatomic glenoid version (independent of the resting position of the scapula) was an average (and standard deviation) of 2.0 degrees +/- 3.8 degrees of retroversion. The average difference between anatomic glenoid version and clinical glenoid version (depending on the position of the scapula on the original computed tomography axial images) was 6.9 degrees +/- 5.6 degrees (range, 0.1 degrees to 22.5 degrees). Version variability with coronal or sagittal rotation was significant for all degrees of rotation (p < 0.0001). Scapular abduction had the greatest effect on version variation and resulted in 0.42 degrees of relative anteversion for every 1 degree of abduction in the coronal plane. In the sagittal plane, internal rotation resulted in relative anteversion. CONCLUSIONS Any malalignment of > or = 1 degree of the scapula in the coronal or sagittal plane will create inaccuracies in measuring glenoid version. The plane of axial reconstruction should be aligned with the scapula when two-dimensional computed tomography images are used to measure glenoid version. These findings support the use of three-dimensional models to evaluate glenoid version.

Comparison of standard two-dimensional and three-dimensional corrected glenoid version measurements

HYPOTHESIS There is concern regarding the accuracy of 2-dimensional (2D) computed tomography (CT) for measuring glenoid version. Three-dimensional (3D) CT scan reconstructions can properly orient the glenoid to the plane of the scapula and have been reported to accurately measure glenoid version in cadaver models. We hypothesized that glenoid version measured by correcting 2D CT scans to the plane of the scapula by 3D reconstruction would be significantly different compared with standard 2D CT scan measurement of the glenoid in a clinical patient population. MATERIALS AND METHODS Thirty-four patients underwent dedicated axial 2D CT scan of the shoulder with 3D reconstruction. The 2D glenoid version was measured on unmodified midglenoid axial cuts, and the 3D glenoid version measurement was corrected to be perpendicular to the plane of the scapula and then measured in the axial plane. Three observers repeated each measurement on 2 different days. RESULTS The difference between the overall average 2D and 3D measurements was not statistically significant (P = .45). In individual scapulae, 35% of 2D measurements were 5° to 10° different and 12% were greater than 10° different from their corresponding 3D-corrected CT measurement (P < .001 to P = .045). Reproducibility of both 2D and 3D-corrected measurements was good. DISCUSSION Although 2D and 3D corrected methods showed a high degree of both intraobserver and interobserver reliability in this series, axial 2D images without correction were 5 to 15 degrees different than their 3D-corrected counterparts in 47% of all measurements. Correcting 2D glenoid version by 3D reconstruction to the transverse plane perpendicular to the scapular body allows for an accurate assessment of glenoid version in spite of positioning differences and results in increased accuracy while maintaining high reliability. CONCLUSIONS Owing to the variability in scapular position, the axial 2D CT scan measurement was significantly different from 3D-corrected measurement of glenoid version. Averaging the version measurements across patients did not reflect this finding.

Improved differentiation of benign osteochondromas from secondary chondrosarcomas with standardized measurement of cartilage cap at CT and MR imaging

PURPOSE To validate a technique for reproducible measurement of the osteochondroma cartilage cap with computed tomography (CT) and magnetic resonance (MR) imaging and to reevaluate the correlation of the thickness of the cartilage cap with pathologic findings to improve noninvasive differentiation of benign osteochondromas from secondary chondrosarcomas. MATERIALS AND METHODS The institutional review board approved the study and waived the need for informed consent. HIPAA compliance was maintained. After validation of the measurement technique, 101 pathologically confirmed osteochondromas were retrospectively reviewed. Patient demographic data, histologic diagnosis, and chondrosarcoma grade were recorded. Two musculoskeletal radiologists used a standardized technique to independently measure the thicknesses of the cartilage caps on CT and MR images; these measurements were compared for interobserver agreement. Agreement between measurements with CT and MR imaging was also evaluated, as were the sensitivity and specificity of both modalities for differentiation of osteochondromas from chondrosarcomas. RESULTS Evaluated were 67 benign osteochondromas (from 49 male patients and 18 female patients; mean age, 23.4 years) and 34 secondary chondrosarcomas (from 27 male patients and seven female patients; mean age, 33.2 years). On the basis of the proposed measuring technique, there was 88% interobserver measurement agreement with MR imaging (95% confidence interval [CI]: 80%, 94%) and 93% with CT (95% CI: 84%, 98%). The median difference between measurements of cap thickness at CT and MR imaging was 0 cm (25th and 75th percentiles, -3 mm and 1 mm, respectively). With 2 cm used as a cutoff for distinguishing benign osteochondromas from chondrosarcomas, the sensitivities and specificities were 100% and 98% for MR imaging and 100% and 95% for CT, respectively. CONCLUSION The proposed measuring technique allows accurate and reproducible measurement of cartilage cap thickness with both CT and MR imaging. Cap thickness of 2 cm or greater strongly indicated secondary chondrosarcomas.

Diagnosis of superior labral lesions: comparison of noncontrast MRI with indirect MR arthrography in unexercised shoulders

ObjectiveTo prospectively compare the accuracy of noncontrast magnetic resonance imaging (MRI) with indirect MR arthrography (I-MRa) of unexercised shoulders for diagnosis of superior glenoid labral lesions.Materials and methodsInstitutional Review Board approval and patient informed consent were obtained for this prospective study. Superior labral findings on shoulder MRI and unexercised I-MRa studies of 104 patients were correlated with findings at arthroscopic shoulder surgery. Two musculoskeletal radiologists independently reviewed the two sets of MR images while blinded to arthroscopic results. For each radiologist, the McNemar test was used to detect statistically significant differences between techniques.ResultsThe superior labrum was intact in 24 and abnormal in 80 subjects. For detection of superior labral lesions by each radiologist, I-MRa was more sensitive (84–91%) than MRI (66–85%), with statistically significant improvement in sensitivity for one reader (p = 0.003). However, I-MRa was less specific (58–71%) than MRI (75–83%). Overall, accuracy was slightly improved on I-MRa (78–86%) compared with MRI (70–83%), but this difference was not statistically significant for either reader.ConclusionCompared with noncontrast MRI, I-MRa was more sensitive for diagnosis of superior glenoid labral lesions. However, the diagnostic value of I-MRa in shoulders remaining at rest is potentially limited by decreased specificity of the technique.

Use of a simulation laboratory to train radiology residents in the management of acute radiologic emergencies.

OBJECTIVE Simulation laboratories use realistic clinical scenarios to train physicians in a controlled environment, especially in potentially life-threatening complications that require prompt management. The objective of our study was to develop a comprehensive program using the simulation laboratory to train radiology residents in the management of acute radiologic emergencies. MATERIALS AND METHODS All radiology residents attended a dedicated simulation laboratory course lasting 3 hours, divided over two sessions. Training included basic patient management skills, management of a tension pneumothorax, massive hemorrhage, and contrast agent reactions. Participants were presented with 20 multiple-choice questions before and after the course. Pre- and posttest results were analyzed, and the McNemar test was used to compare correct responses by individual question. RESULTS Twenty-six radiology residents attended the class. The average pre- and posttest scores and the average difference between the scores for all residents were 13.8, 17.1, and 3.3, respectively (p < 0.0001). Incorrect answers on the pretest examination that were subsequently answered correctly concerned administration of epinephrine for severe reactions, management of a tension pneumothorax, oxygen therapy, ECG placement, cardiopulmonary resuscitation technique, and where to stand during a code situation. Persistent incorrect answers concerned vasovagal reactions and emergency telephone numbers at an off-site imaging center. CONCLUSION Simulation laboratories can be used to teach crisis management and crisis resource management for radiology residents and should be part of the education toolbox. Defined objectives lead to a comprehensive course dealing with the management of acute radiologic emergencies. Such programs can improve the role of radiologists as members of the health care team.

Femoroacetabular Impingement: Screening and Definitive Imaging

Femoroacetabular impingement (FAI) is a recently described entity that occurs when there is impaction of the femoralheadorneckonthelabrumandacetabularrimofthe pelvis secondary to either acquired or developmental abnormality of the femoral head and or acetabulum. 1,2 This abnormal osseous morphology leads to chronic impaction at the extremes of range of motion and subsequent damage of the labrum and articular cartilage. It is critical for the radiologist to have a thorough understanding of this entity because FAI is currently believed to be an important contributor to the early development of osteoarthritis in young patients. However, the natural history of this disorder has not been established, and there is some controversy about the significance of radiologic manifestations of FAI because they can be seen in asymptomatic individuals. The role of the radiologist in the assessment of FAI is 2-fold, screening and definitive evaluation. Screening is usually performed through plain radiography but the findings of FAI may also be recognized on wide field-of-view (FOV) magnetic resonance (MR) imaging (MRI) of the pelvis that is frequently performed for the general evaluation of hip pain. The interpreting radiologist must be sensitive to often subtle findings that may indicate that FAI is responsible or contributing to pain in young patients. Definitive evaluation is usually performed with dedicated imaging of the symptomatic hip by MRI arthrography although noncontrast imaging and, to a lesser extent, computed tomography (CT) have roles in the assessment of suspected FAI.

Subscapularis function after total shoulder arthroplasty: electromyography, ultrasound, and clinical correlation

BACKGROUND The literature lacks electromyographic (EMG) examination of subscapularis function in the postoperative period after total shoulder arthroplasty (TSA). The primary purpose of this study was to document EMG activity of the subscapularis after TSA and to correlate it with clinical and ultrasound findings. METHODS The study included 30 patients who were at least 1 year (average, 2.1 years) from surgery, status post TSA approached through a standard subscapularis tenotomy. Patients returned for a physical examination, ultrasound evaluation, and EMG evaluation. Patients also completed postoperative surveys: the American Shoulder and Elbow Surgeons questionnaire, the Simple Shoulder Test, and the 12-Item Short Form Health Survey. RESULTS The American Shoulder and Elbow Surgeons, Simple Shoulder Test, and physical 12-Item Short Form Health Survey scores improved from preoperatively to postoperatively, respectively, 45.3 to 76.8 (P = .0002), 3.9 to 9.0 (P < .0001), and 33.9 to 42.8 (P = .017). Six patients had a positive lift-off test result, and the belly-press test result was negative in all patients. Two patients had a subscapularis rupture on ultrasound. The postoperative EMG finding was normal in 15 patients; in the other 15 patients, there was evidence of chronic denervation with reinnervation changes: 30% subscapularis, 27% infraspinatus, 20% supraspinatus, 20% teres minor, and 13% rhomboids. CONCLUSIONS This is the first study using a comparison EMG evaluation to document subscapularis function after TSA. EMG evaluation showed that active denervation of the subscapularis was not evident in any patient at least 1 year after TSA. However, in half of the patients, there was evidence of chronicdenervation and reinnervation changes across 5 muscle groups. We theorize that surgical exposure, traction, and the use of interscalene regional anesthesia may contribute to these unexpected EMG results.

MR imaging assessment of arthritis of the knee.

The magnetic resonance (MR) imaging presentations of arthritis of the knee are important for radiologists to recognize because these disorders are often clinically unsuspected. When they are known or clinically suspected, knowledge of imaging features allows for the confirmation and characterization of the extent of disease. This article reviews the fundamental MR imaging manifestations of rheumatologic disorders of the knee and their presentation in specific arthropathies.

Primary osseous tumors of the spine.

Primary osseous spinal tumors are relatively rare in comparison with metastatic disease, myeloma, and lymphoma. Despite their rarity, the interpreting radiologist must be aware of the typical imaging features to provide appropriate diagnosis for guidance of clinical management. The age of occurrence, distribution longitudinally in the spine, and distribution axially within the vertebra combined with typical imaging appearances can help indicate the correct diagnosis. This article reviews the diagnostic features of benign and malignant primary bone spinal tumors.