Inter-rater agreement of rotator cuff tendon and muscle magnetic resonance imaging parameters evaluated preoperatively and during the first postoperative year following rotator cuff repair.

BACKGROUND: Magnetic resonance imaging (MRI) is standard of care for rotator cuff evaluation, with clinical interpretation usually limited to qualitative judgments. The reliability of MRI-based measurements and scoring systems has been evaluated only preoperatively or ≥6 months following rotator cuff repair, when repairs are in the later stages of healing. This study describes the MRI assessments and inter-rater agreement of various rotator cuff tendon and muscle parameters evaluated preoperatively and 4 times during the first postoperative year. METHODS: Two musculoskeletal radiologists independently assessed MRI scans of 42 patients preoperatively and 3, 12, 26, and 52 weeks after rotator cuff repair. Using standardized reading rules, readers assessed tendon integrity (5-point Sugaya classification), tear dimensions, muscle fat (5-point Goutallier classification) and atrophy (4-point Warner classification), muscle cross-sectional areas, and myotendinous junction distance. Raw exact agreement proportions, κ statistics, and correlation coefficients were used to quantify inter-rater agreement. RESULTS: Readers showed moderate to substantial above-chance agreement in scoring rotator cuff tendon integrity and supraspinatus muscle atrophy and good to excellent agreement on tear dimensions and muscle cross-sectional areas but only fair to moderate agreement for fatty infiltration and myotendinous junction distance. Only fatty infiltration grades evidenced observer bias. Inter-rater agreement did not appear time dependent. CONCLUSION: By use of defined reading rules in a research setting, MRI evaluations of rotator cuff tendon integrity, tear dimensions, muscle atrophy, and cross-sectional areas have reasonable reliability at all time points in the first postoperative year. However, the presence of clinically significant disagreements, even in such favorable circumstances, indicates the need for improved imaging tools for precise rotator cuff evaluation.

Comparison of Clinical and Semiquantitative Cartilage Grading Systems in Predicting Outcomes After Arthroscopic Partial Meniscectomy.

OBJECTIVE. Cartilage loss on preoperative knee MRI is a predictor of poor outcomes after arthroscopic partial meniscectomy. The purpose of this study was to compare the ability to predict outcomes after arthroscopic partial meniscectomy with a clinically used modified Outerbridge system versus a semiquantitative MRI Osteoarthritis Knee Score system for grading cartilage loss. MATERIALS AND METHODS. Patients who underwent preoperative knee MRI within 6 months of arthroscopic partial meniscectomy and who had outcomes available from the time of surgery and 1 year later were eligible for inclusion. Cases were evaluated by two radiologists and one radiology fellow with the use of both grading systems. The accuracy of each system in discriminating between surgical success and failure was estimated using the ROC curve (AUC) with 95% CIs. A Wald test was used to assess noninferiority of the clinical grading system. Interreader agreement regarding the accuracy of the grading systems in predicting outcomes was also compared. RESULTS. A total of 78 patients (38 women and 40 men; mean age, 56.6 years) were included in the study. A prediction model using clinical grading (AUC = 0.695; 95% CI, 0.566-0.824) was noninferior (p = 0.047) to a model using MRI Osteoarthritis Knee Score grading (AUC = 0.683; 95% CI, 0.539-0.827). Both MRI prediction models performed better than a model using demographic characteristics only (AUC = 0.667; 95% CI, 0.522-0.812). Inter-reader agreement with clinical grading (80.8%) was higher than that with MRI Osteoarthritis Knee Score grading (65.0%; p = 0.012). CONCLUSION. A clinically used system to grade cartilage loss on MRI is as effective as a semiquantitative system for predicting outcomes after arthroscopic partial meniscectomy, while also offering improved interreader agreement.

Comparison of a Fast 5-Minute Shoulder MRI Protocol With a Standard Shoulder MRI Protocol: A Multiinstitutional Multireader Study.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of a 5-minute shoulder MRI protocol consisting of multiplanar 2D fast spin-echo (FSE) sequences with parallel imaging to that of a standard shoulder MRI protocol. MATERIALS AND METHODS: A retrospective review of 151 3-T MRI examinations of shoulders of 147 patients (mean age, 46.95 years) and 50 1.5-T MRI examinations of shoulders of 50 patients (mean age, 53.74 years) with four fast and five standard sequences from two academic centers between January 2014 and April 2015 was performed by three musculoskeletal radiologists. Interchangeability of fast and standard MRI was tested by comparing interprotocol (fast vs standard) interreader agreement with standard MRI interreader agreement. Interreader agreement was also compared using kappa statistics. The frequency of major findings was compared using an adjusted McNemar test. Sensitivity and specificity of MRI were measured for 51 patients who underwent surgery. RESULTS: Interprotocol reader agreement was essentially equal to reader agreement on standard MRI (mean difference ≤ 1%; 95% CI, -3.8% to 3.9%; 61-96% across structures). Interprotocol kappa values (0.373-0.645) were similar to standard MRI kappa values (0.320-0.726). Frequencies of major findings on fast and standard MRI were similar (0.7-19.6% across structures; p ≥ 0.08). Sensitivities of fast MRI for tendon and labral tears (33-92%) were equivalent or higher than those of standard MRI with similar specificities (77-98%). CONCLUSION: Fast 5-minute shoulder MRI with multiplanar 2D FSE sequences using parallel imaging is interchangeable, with similar interreader agreement and accuracy, with standard shoulder MRI for evaluating shoulder injuries.

Failure with continuity in rotator cuff repair "healing".

BACKGROUND: Ten to seventy percent of rotator cuff repairs form a recurrent defect after surgery. The relationship between retraction of the repaired tendon and formation of a recurrent defect is not well defined. PURPOSE/ HYPOTHESES: To measure the prevalence, timing, and magnitude of tendon retraction after rotator cuff repair and correlate these outcomes with formation of a full-thickness recurrent tendon defect on magnetic resonance imaging, as well as clinical outcomes. We hypothesized that (1) tendon retraction is a common phenomenon, although not always associated with a recurrent defect; (2) formation of a recurrent tendon defect correlates with the timing of tendon retraction; and (3) clinical outcome correlates with the magnitude of tendon retraction at 52 weeks and the formation of a recurrent tendon defect. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Fourteen patients underwent arthroscopic rotator cuff repair. Tantalum markers placed within the repaired tendons were used to assess tendon retraction by computed tomography scan at 6, 12, 26, and 52 weeks after operation. Magnetic resonance imaging was performed to assess for recurrent tendon defects. Shoulder function was evaluated using the Penn score, visual analog scale (VAS) score for pain, and isometric scapular-plane abduction strength. RESULTS: All rotator cuff repairs retracted away from their position of initial fixation during the first year after surgery (mean [standard deviation], 16.1 [5.3] mm; range, 5.7-23.2 mm), yet only 30% of patients formed a recurrent defect. Patients who formed a recurrent defect tended to have more tendon retraction during the first 6 weeks after surgery (9.7 [6.0] mm) than those who did not form a defect (4.1 [2.2] mm) (P = .08), but the total magnitude of tendon retraction was not significantly different between patient groups at 52 weeks. There was no significant correlation between the magnitude of tendon retraction and the Penn score (r = 0.01, P = .97) or normalized scapular abduction strength (r = -0.21, P = .58). However, patients who formed a recurrent defect tended to have lower Penn scores at 52 weeks (P = .1). CONCLUSION: Early tendon retraction, but not the total magnitude, correlates with formation of a recurrent tendon defect and worse clinical outcomes. "Failure with continuity" (tendon retraction without a recurrent defect) appears to be a common phenomenon after rotator cuff repair. These data suggest that repairs should be protected in the early postoperative period and repair strategies should endeavor to mechanically and biologically augment the repair during this critical early period.

Accuracy of MRI in the diagnosis of meniscal tears in older patients.

OBJECTIVE: The objective of our study was to determine the accuracy of MRI in diagnosing meniscal tears in older patients and the frequency with which abnormal MRI findings correlate with degeneration, fraying, and tears at arthroscopy. MATERIALS AND METHODS: Ninety-two patients 50 years old or older who had undergone knee MRI followed by knee arthroscopy within 6 months were selected. Menisci were graded on a 5-point scale: 1, definitely no tear; 2, probably no tear; 3, indeterminate or equivocal; 4, probably a tear; and 5, definitely a tear. Meniscal signal changes, meniscal surface morphology, and extrameniscal abnormalities were noted. Operative notes were reviewed, and the sensitivity and specificity of MRI results were calculated. RESULTS: For medial tears, MRI had a sensitivity and specificity of 0.91 and 0.94, respectively, when grade 5 was considered a tear, 0.96 and 0.76 when grades 4 and 5 were considered a tear, and 0.99 and 0.47 when grades 3-5 were considered a tear. For lateral tears, MRI had a sensitivity and specificity of 0.73 and 0.91 when grade 5 was considered a tear, 0.88 and 0.80 when grades 4 and 5 were considered a tear, and 1.0 and 0.61 when grades 3-5 were considered a tear. The positive predictive values (PPVs) of MRI for the medial meniscus were 99%, grade 5; 57%, grade 4; 29%, grade 3; 25%, grade 2; and 0%, grade 1. For the lateral meniscus, the PPVs of MRI were 76%, grade 5; 36%, grade 4; 19%, grade 3; and 0%, grades 1 and 2. CONCLUSION: The accuracy of MRI for diagnosing meniscal tears in older patients is high and similar to that in younger patients when only definitive findings are considered a tear. The specificity decreases if equivocal or probable findings are considered a tear.

MRI of the knee ligaments and menisci: comparison of isotropic-resolution 3D and conventional 2D fast spin-echo sequences at 3 T.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) 3D fast spin-echo acquisition relative to conventional 2D fast spin-echo acquisition in the 3-T MRI evaluation of the menisci and ligaments of the knee. MATERIALS AND METHODS: Images from all MRI knee examinations performed with a single 3-T system from September 2008 to January 2009 were reviewed. Seventy-one examinations of patients who subsequently underwent knee arthroscopy and an additional 29 examinations of patients who did not undergo surgery were selected for a total of 100 examinations. All imaging was performed with multiplanar conventional 2D and SPACE 3D fast spin-echo acquisitions. Six musculoskeletal radiologists independently reviewed the images. Area under the receiver operating characteristic (ROC) curve was calculated for the menisci and anterior cruciate ligament with arthroscopy as the reference standard. Disagreement between the two acquisitions was calculated for the posterior cruciate ligament and medial and lateral collateral ligaments. The Wilcoxon signed rank test was used to compare each reader's confidence scores for the two techniques. RESULTS: For the medial meniscus, the average area under the ROC curve was statistically significantly larger (p = 0.01) with the conventional 2D (0.931) than with the SPACE 3D (0.893) technique. Average confidence in diagnosing medial meniscal tears also was statistically significantly greater with the 2D than with the 3D technique (p = 0.001). No statistically significant differences were found for the lateral meniscus or anterior cruciate ligament. The rate of discordance between findings with the 2D and 3D techniques was low for the posterior cruciate ligament and medial and lateral collateral ligaments (range, 4.2-5.7%). CONCLUSION: In evaluation of menisci with 3-T MRI, readers performed better with conventional 2D acquisition than with SPACE 3D acquisition. In evaluation of ligaments, the readers had similar performance with the two acquisition methods.

Vacuum phenomenon: prevalence and appearance in the knee with 3 T magnetic resonance imaging.

OBJECTIVES: To determine the prevalence of vacuum phenomenon (VP) in the knee on magnetic resonance (MR) images, describe the imaging features that characterize VP, and assess how often VP mimics pathological knee lesions. MATERIALS AND METHODS: Consecutive knee MR studies performed on a 3 T MR system over a 9-month period were retrospectively reviewed by one radiologist who then selected studies with findings potentially indicating VP. Three experienced musculoskeletal radiologists reviewed these cases in consensus to confirm the presence of VP and to assess the shape, size, and signal of VP; the presence of magnetic susceptibility artifacts; and the ability of MR sequences to show VP. RESULTS: A total of 914 consecutive exams from 875 patients (524 men; mean age, 35 years) were reviewed. Vacuum phenomenon was found in 12 patients (prevalence 1.3%). In six (50%) patients, VP mimicked a meniscal tear, with four cases simulating a torn medial discoid meniscus. The VP signal was not easily differentiated from meniscal signal on most sequences in most cases (9/12). Gradient-recalled echo (GRE) localizer images proved most definitive, with 3D SPACE images the next most effective. Fast spin echo (FSE) images were only occasionally able to differentiate VP from meniscus. CONCLUSION: Rarely recognized on MR, VP can mimic meniscal pathology, potentially leading to inappropriate surgery. Because differentiation of VP from the meniscus is challenging on FSE at 3 T, radiologists should become familiar with the appearance of VP and review GRE localizer or 3D images carefully to avoid misinterpretation.

Shoulder MRI: what do we miss?

OBJECTIVE: Our aim is to review several shoulder abnormalities that are difficult to detect accurately on shoulder MRI, describe the technical reasons that limit their detection, and suggest imaging protocol modifications that may improve radiologists' accuracy. CONCLUSION: Although MRI is an excellent tool for detecting some abormalities, there are a number of subtler abnormalities of clinical significance that give radiologists greater difficulty. By understanding the reasons for limited detection and modifying protocols accordingly, radiologists may be able to improve identification, allowing more accurate clinical decision making.

Postoperative single-fraction radiation for prevention of heterotopic ossification of the elbow.

PURPOSE: Heterotopic ossification (HO) about the elbow has been described after surgery, trauma, and burns. Even limited deposits can lead to significant functional deficits. Little data exist regarding outcomes of patients treated with radiation therapy (RT) after elbow surgery. We report here the Cleveland Clinic experience with single-fraction radiation following surgery to the elbow. The primary endpoint was the rate of new HO after RT. Secondary endpoints were range of motion, functional compromise, and toxicity. METHODS AND MATERIALS: From May 1993 to July 2006, 36 patients underwent elbow surgery followed by single-fraction RT. Range of motion data were collected before and during surgery and at last follow-up. Radiographs were reviewed for persistent or new HO. Patient and treatment factors were analyzed for correlation with development of HO or functional compromise. RESULTS: Median follow-up was 8.7 months, median age was 42 years, and 75% of patients were male. Twenty-six (72%) patients had HO prior to surgery. All patients had significant limitations in flexion/extension or pronation/supination at baseline. Thirty-one (86%) patients had prior elbow trauma, and 26 (72%) patients had prior surgery. RT was administered a median of 1 day postoperatively (range, 1-4 days). Thirty-four patients received 700 cGy, and 2 patients received 600 cGy. Three (8%) patients developed new HO after RT. All patients had improvement in range of motion from baseline. No patient or treatment factors were significantly associated with the development of HO or functional compromise. CONCLUSIONS: Single-fraction RT after surgery to the elbow is associated with favorable functional and radiographic outcomes.

Three-dimensional volume-rendering computed tomography for measuring humeral version.

HYPOTHESIS: Humeral version is highly variable in human beings. Accurate assessment of humeral version may allow for more anatomic reconstruction at shoulder arthroplasty. Two-dimensional (2D) computed tomography (CT) has been used to measure humeral version but has limitations of poor interobserver reproducibility and strict dependence on arm positioning during image acquisition. This study evaluated a new technique, 3-dimensional (3D) volume rendering, for measuring humeral version. MATERIALS AND METHODS: Eight dried human humerus specimens were included in the study. Gold standard measurements of humeral version were obtained by use of metallic beads and fluoroscopy. The specimens were then scanned at CT in 2 different positions, 1 neutral to the table and 1 angled at 20 degrees . The image data sets were used to measure humeral version in each bone with both the standard 2D technique and the new 3D technique. Measurements were performed by 3 readers at 2 different time points. Readers were blinded to the gold standard results and each others' measurements. RESULTS: For all readers, 3D measurements averaged within 4.3 degrees of the gold standard. For 2 of the 3 readers, 3D measurements were more accurate than 2D measurements. For all 3 readers, intraobserver variability was better with the 3D technique. For all reader pairs, interobserver variability was better with the 3D technique. CONCLUSIONS: This study shows a 3D volume-rendering CT technique to measure humeral version accurately and consistently that is independent of patient positioning.

Comparison of MR arthrography with arthroscopy of the hip for the assessment of intra-articular loose bodies.

OBJECTIVE: To assess the specificity and sensitivity of MR arthrography of the hip in comparison with arthroscopy for the evaluation of intra-articular loose bodies. DESIGN: Over a 3-year period, 81 consecutive patients underwent a total of 82 hip arthroscopies by a single orthopedic surgeon for intractable hip pain. Of the 82 arthroscopies, 70 had pre-operative MR arthrograms. Of these, 57 were available for retrospective review, after which they were compared with the operative notes of the subsequent arthroscopies. RESULTS: Of 82 arthroscopies 16 (20%) demonstrated intra-articular loose bodies, while, in the study group, nine of 57 had loose bodies (16%). There was a total of seven discordant cases (five false negatives and two false positives). The sensitivity of MR arthrography for detection of intra-articular loose bodies was 44%, while the specificity was 96%. CONCLUSION: While the specificity of MR arthrography for the detection of intra-articular loose bodies was high (96%), the sensitivity was not nearly as good (44%).