Faculty Bibliography

Purpose: To compare the accuracy of an optimized 3D TSE (SPACE) sequence using SPARSE-SENSE (SS) acceleration with 2D TSE sequences for the detection of internal derangement of the knee. Materials and Methods: An optimized accelerated SPACE sequence prototype was developed using avariable-density poisson-disc undersampling pattern of the two phase-encoding dimensions. Optimized parameters were: TR1100, TE22, TF28, variable flip angle evolution for PD weighting, SS undersampling factor of 9, fat suppression, presence of an optimized MT module, and 0.5 x 0.5 x 0.6 mm3 voxel size. This sequence (TA 4:57) was added to our conventional knee examination (sagittal PD and FS T2, coronal PD and FS PD, axial FS T2 2D TSE sequences (TA 10:56)) for 579 patients undergoing knee MR examinations imaged on a 3T scanner (Magnetom Skyra, Siemens Healthcare). An iterative SS reconstruction [2] was performed by enforcing sparsity in the wavelet representation of the knee images. Images were then reformatted in all 3 orthogonal planes at 1.5mmthickness. 50 of the 579 patients underwent arthroscopy of the knee and two experienced MSK radiologists blindly reviewed the SS SPACE sequence and the conventional 2D TSE sequences of these 50 patients at separate sittings to evaluate for the presence of meniscal or ligamentous tears. Results: 38 patients hadmedialmeniscal tears, 23 had lateral meniscal tears, and 16 had ACL tears. There was only 1 MCLand PCL tear and there were no LCL tears. The sensitivity, specificity, and accuracy for medial meniscal, lateral meniscal, and ACL tears on the 2D TSE images and SS Space images for each reader are presented below. Sensitivity Specificity Accuracy Sensitivity Specificity Accuracy Conclusion: An optimized and accelerated 3D TSE sequence has the potential to replace 2D TSE sequences for evaluation of internal derangement of the knee. If substantiated in larger clinical studies, this could lead to significant shortening of exam time, potentially enlarging the indication and utilization of knee MR as well as decreasing its cost

Purpose: iBalance high tibial osteotomy, (iHTO, Arthrex Inc, Naples, Florida), is a recently introduced surgical procedure for correction of knee varus malalignment. iHTO, utilizing a polyetheretherketone (PEEK) implant and osteoinductive compounds (OIC), presents challenging post operative radiographs which can easily be misinterpreted as infection. Our purpose is to report, based on review of 24 cases, the previously undescribed to the best of our knowledge, radiographic features of iHTO and its complications. Materials and Methods: Retrospective query of our digital database was performed to identify iHTO cases. The clinical and postsurgical images in all cases with > 1-month follow up imaging were reviewed with attention to 1. Correction of varus malalignment, 2. Healing at the osteotomy site, 3. Changes in the OIC, and 4. Complications. Results: There were 24 iHTOs in 23 patients (17 men, 6 women, ages 21-59, mean 44, median 46), imaged 1 to 29 months post-surgery, with angle of correction, when available, ranging from 5 to 14degree. Immediate post-surgical correction of varus malalignment was seen in 100 % of patients. 100 % depicted oval radiolucencies, at bone PEEK interface simulating erosions and infection. Four, often overlapping, signs of healing were noted: 1. Blurring of bony margins at the osteotomy site, noted within 2 weeks post surgery, 2. Blurring of sharp interface between OIC and host bone, 3. Anterior, posterior and less commonly medial bridging callus, 4. Resorption of OIC, noted as early as 4 months. Complications, seen in 7 cases (29 %), included genu varum recurrence (n = 2), painful exuberant bone formation, (n = 1), and propagation of the osteotomy through the lateral tibial cortex (n = 4). In patients with >6 months follow-up, nonunion and possible infection was seen in 1 patient. 2 patients required total knee arthroplasty due to iHTO failure. Conclusion: iBalance HTO typically depicts oval radiolucencies at the PEEK bone interface not to be mistaken for infection. Familiarity with this features, as well as with other signs of healing, should aid the radiologist in accurate interpretation of post operative films of iHTO patients

Purpose: (1) To analyze the use of multi-segmental computed tomography (CT) imaging in the emergency department (ED) for patients with a primary spine complaint in terms of diagnosing new, clinically relevant pathology; (2) To define predictor variable( s) for new pathology on ED CT spine imaging Materials and Methods: We performed a retrospective review of multi-segmental CT performed in the ED over a 24-month period for patients presenting with primary spine related complaints. Multi-segmental CT was defined as an examination that included more than one spine segment (cervical, thoracic, and/or lumbar). The data reviewed for each patient included age, gender, chief complaint, patient history, physical examination findings, ED management, and pertinent imaging. New pathology on CT was defined as a new fracture, progression of a known vertebral body compression fracture, new disc herniation, new discitis/osteomyelitis, new ligament injury, and/or new metastasis. Potential predictor variables evaluated included age, gender, history of trauma, and history of malignancy. Statistical analysis included Fisher's exact test, logistic regression, and ROC curve analysis. Results: Forty-two patients, 22 males/20 females (mean age of 70.4 years; range 29-96), were included in the study. There were 32 total spine examinations, 9 thoracolumbar examinations, and 1 cervicothoracic examination, and 116 spinal segments imaged, overall. Fifty percent of the imaging examinations (44 % total spine; 70 % non-total spine) demonstrated a new imaging finding. The most common finding was an acute fracture (16), including four patients who had new pathologic fractures of the vertebral bodies secondary to new metastatic disease. Overall, 22.4 % (26/116) of the imaged segments revealed new pathology, 29.3 % lumbar spine, 21.4 % thoracic spine, and 15.2 % cervical spine. New pathology seen on imaging directly corresponded to findings in the patient's clinical history and/or physical examination in 30 % of the imaged segments, most common in the lumbar spine (34.5 %) and least common in the cervical spine (20 %). New imaging findings were found in 15 % of segments that had no corresponding finding in the patient's clinical history or on physical examination, most common in the lumbar spine (16.7 %). History of cancer, trauma, and/or gender were not found to be predictive for new findings on CT, while age was found to be a significant predictor (p = 0.015). When age was used to predict whether new pathology would be detected in spine segments without concern based on clinical history and/or physical examination, area under the ROC curve was 0.741. If a decision rule was created for our study patients such that, 1) patients > 70 years undergo imaging of all three spine segments, and 2) patients < 70 years undergo imaging only where clinical history or physical exam suggest reason for concern, a 24.3 % reduction in imaging would have been realized while maintaining an accuracy of 96.2 % in uncovering new pathology. Conclusion: Our study suggests that spine CT imaging may be overutilized in the emergency department. The use of a patient age threshold may allow for better CT utilization and reduce unnecessary imaging in this setting

OBJECTIVE: The objectives of the article are to improve the radiologist's understanding of shoulder arthroscopy and see how it correlates with MRI. We review the basic principles of arthroscopy followed by a comparison of its strengths and weaknesses relative to MRI. This discussion is supplemented by a series of cases that show the relationship between arthroscopy and MRI in terms of the visualization of normal and abnormal anatomy in the diagnosis of common shoulder abnormalities. CONCLUSION: By understanding what our orthopedic colleagues are seeing (and not seeing) during arthroscopic shoulder surgery, we can better understand the strengths and weaknesses of MRI, which provides us the opportunity to improve our imaging interpretations and produce valuable management-guiding diagnostic reports.

BACKGROUND: Gout and osteoarthritis (OA) are the most prevalent arthritides, but their relationship is neither well established nor well understood. OBJECTIVES: We assessed whether a diagnosis of gout or asymptomatic hyperuricemia (AH) is associated with increased prevalence/severity of knee OA. METHODS: One hundred nineteen male patients aged 55 to 85 years were sequentially enrolled from the primary care clinics of an urban Veterans Affairs hospital, assessed and categorized into 3 groups: gout (American College of Rheumatology Classification Criteria), AH (serum urate >/=6.8 mg/dL, no gout), and control (serum urate <6.8 mg/dL, no gout). Twenty-five patients from each group subsequently underwent formal assessment of knee OA presence and severity (American College of Rheumatology Clinical/Radiographic Criteria, Kellgren-Lawrence grade). Musculoskeletal ultrasound was used to detect monosodium urate deposition at the knees and first metatarsophalangeal joints. RESULTS: The study showed 68.0% of gout, 52.0% of AH, and 28.0% of age-matched control subjects had knee OA (gout vs control, P = 0.017). Odds ratio for knee OA in gout versus control subjects was 5.46 prior to and 3.80 after adjusting for body mass index. Gout subjects also had higher Kellgren-Lawrence grades than did the control subjects (P = 0.001). Subjects with sonographically detected monosodium urate crystal deposition on cartilage were more likely to have OA than those without (60.0 vs 27.5%, P = 0.037), with crystal deposition at the first metatarsophalangeal joints correlating most closely with OA knee involvement. CONCLUSIONS: Knee OA was more prevalent in gout patients versus control subjects and intermediate in AH. Knee OA was more severe in gout patients versus control subjects.

Purpose: To demonstrate that sonographic morphologic properties of the supraspinatus tendon correlate with mechanical properties, as assessed quantitatively by shear-wave ultrasound elastography.
Material(s) and Method(s): This retrospective study included 36 patients who underwent sonographic evaluation of one or both shoulders on one or multiple dates from June 2013 through October 2014. A shoulder was excluded if the supraspinatus tendon contained calcifications or had undergone surgical repair for a tear. Each sonographic evaluation of each shoulder was regarded as a separate data point, totaling 76 sonographic evaluations of 36 patients. For each sonographic evaluation, the morphologic appearance of the proximal and distal supraspinatus tendon was graded (1 = normal or mild tendinosis without a tear, 2 = moderate or severe tendinosis without a tear, 3 = partial tear, 4 = full-thickness tear) by consensus of 2 musculoskeletal radiologists. In addition, for each sonographic evaluation, sample volumes were randomly placed within the proximal and distal supraspinatus tendon, viewed in the longitudinal dimension, to obtain shear-wave ultrasound elastography measurements. Finally, for 68 of the sonographic evaluations, on the same image used for sample volumes of the supraspinatus tendon, sample volumes were randomly placed within the deltoid muscle to obtain shear-wave ultrasound elastography measurements. Spearman rank correlations assessed the association between tendonmorphology grade and elastographymeasurements. Mann-Whitney tests compared elastography measurements between scans grouped by symptomatology or morphology grade. Bootstrap re-sampling procedures accounted for lack of statistical independence among scans of the same patient.
Result(s): Of the 36 patients, there were 21 males and 15 females (mean age 46, range 23-74). Of the 76 sonographic evaluations, there were 38 males and 38 females (mean age 44, range 23-74), 36 right and 40 left shoulders, and 21 symptomatic and 55 asymptomatic shoulders. The tendon morphology grade and elastography measurements were correlated in both the proximal (p < 0.001) and distal (p = 0.002) supraspinatus tendon. Comparing between grade 1 and grade >= 2 morphology, the elastography measurements differed significantly in both the proximal (p = 0.001) and distal (p = 0.012) supraspinatus tendon. Comparing between grade <= 2 and grade > 2 morphology, the elastography measurements also differed significantly in both the proximal (p = 0.002) and distal (p = 0.004) supraspinatus tendon. Interestingly, deltoid muscle elastography measurements also were associated with the morphology grade of the proximal (p = 0.004) and distal (p = 0.007) supraspinatus tendon; this measurement also differed significantly between asymptomatic and symptomatic scans (p = 0.001).
Conclusion(s): The sonographic morphologic properties of the supraspinatus tendon correlate with mechanical properties, as assessed by shear-wave ultrasound elastography. These findings indicate that shear-wave ultrasound elastography - a non-invasive, relatively inexpensive, and simple examination - can provide an objective measurement of tendon elasticity. Correlation of deltoid muscle elasticity with supraspinatus tendon morphology and symptomatology may be related to the two muscles being a force couple. Further research is needed to assess whether tendon elastography measurements correlate with the MRI morphologic appearance of the tendon and with intraoperative evaluation of tendon quality

Purpose: To see if 3D imaging could improve our understanding of rotator cuff tendon tear shapes on MRI.
Method(s): We performed a retrospective review of 1.5T/3T MR examinations, conducted over an 18-month period, of patients with arthroscopically proven full- thickness rotator cuff tears. Two orthopaedic surgeons reviewed the operative reports/arthroscopic photos for each patient, and characterized, in consensus, the shape of the tear based on a comparison of the tear's width (size) and length (retraction), and involvement of the rotator interval without measurements into the following categories: crescent, longitudinal, U or L-shaped longitudinal, and massive- type. Two musculoskeletal radiologists reviewed the pre-operative MR examination for each patient independently/blind to the arthroscopic findings. Initially, the readers characterized the shape of the tendon tears by reviewing the standard 2DMR sequences and using the same criteria as the surgeons used during their review of the scope images. Next, the readers measured and documented the width and length of each tendon tear using the 2D images. The shape of the tear was then classified based on a previously published MR-based system as either crescent, longitudinal, U or L-shaped, or massive. Four weeks after the initial imaging evaluation, 3DMR reconstructions of each tear were reviewed and the shape documented by each radiologist independently/blind to the arthroscopic results using the same system used by our orthopaedic colleagues. These results were then compared to the 2D imaging evaluations and arthroscopic findings. Statistical analysis included 95% confidence intervals, McNemar test, and intra-class correlation coefficients.
Result(s): A total of 34 patients were included in the study; 21 had crescent shaped tears and 13 had longitudinal tears during arthroscopy. Of the 13 longitudinal tears, 8 were subtyped as U-shaped, while 5 were described as L-shaped. 6 of the 13 longitudinal tears were additionally classified as massive-type. There was no significant difference when comparing the accuracy of the tear shape characterizations made on 2DMR imaging without measurements (pre) and with measurements (post). The accuracy for differentiating between crescent shaped, longitudinal, and massive tears was the same for reader 1, 70.6% (24/34; p=1) and more accurate using the post 2D data for reader 2 (67.6%(post) vs. 61.8%(pre), p=0.5). The accuracy for tear shape characterization between crescent and longitudinal using the 3D reconstructions for reader #1 was 97.1%(33/34) and 88.2% (30/34) for reader #2. When this characterization included subclassifying the longitudinal tears into U or-L shaped, the accuracy for reader #1 was 97.1% and 82.4% for reader #2. When further characterizing the longitudinal tears as massive or not, both readers had an accuracy of 76.9% (10/13). The overall accuracy of the 3D reconstructions was 82.4% (56/68), significantly different (p=0.021) from the post 2D accuracy (64.7%) and pre 2D accuracy (60.3%, p=0.001). The intraclass correlation coefficient for the 2D measurements of width and length were 0.81, moderate agreement, for width and 0.95, strong agreement, for length.
Conclusion(s): Our study has demonstrated that 3DMR reconstructions of the rotator cuff improve the accuracy of characterizing rotator cuff tear shapes compared to the current 2DMR imaging based techniques

Purpose: To see if failure of arthroscopic shoulder stabilization can be predicted by the evaluation of bipolar bone loss on MRI Methods: A retrospective review of 39 consecutive patients (40 shoulders) who underwent arthroscopic capsulolabral repair for recurrent, traumatic, anterior shoulder instability was performed. There were a total of 40 MRIs from 39 patients (31males, 8 females, mean age 31.7 yrs.). Mean follow-up was 19 months. Pre-operative plain radiographs, MRI scans, operative reports, arthroscopic photos, and post-operative records were reviewed for each patient. Surgical failure was defined as recurrent shoulder dislocation and/or persistent apprehension during normal range of motion. Each preoperative MRI scan was evaluated for bipolar bone loss by one musculoskeletal radiologist using the on-track/off-track (OOT) method in which the glenoid track (GT) and Hill-Sachs interval (HSI) aremeasured. According to this technique, the GT is calculated as 0.83D-d in which "D" represents the diameter of the intact glenoid and "d" corresponds to the amount of glenoid bone loss. The HSI represents the width of the Hill-Sachs lesion plus the width of the intact bone bridge between the rotator cuff attachment and the lateral aspect of the Hill-Sachs lesion. All measurements were in millimeters. Lesions were considered "off-track" if the HSI exceeded the GT and "on-track" if the HSI was less than the GT. These findings were then compared to the corresponding post-operative outcomes. Statistical analysis was carried out using the Fisher exact test.
Result(s): Of the 40 shoulders evaluated, 6 were considered surgical failures (3 with recurrent dislocation and 3 with persistent apprehension). The OOT method correctly predicted 1 of these failures and falsely predicted 6 failures in shoulders that were clinically stable. There was no significant difference when comparing stable to unstable shoulders with regards to age, size of GTand HSI. Overall, the OOT method sensitivity was 16.7% (1/6), specificity 82.4% (28/34), positive predictive value 14.3% (1/7), negative predictive value 84.9% (28/33) and overall accuracy 72.5% (29/40).
Conclusion(s): MRI evaluation of bipolar (humeral and glenoid) bone loss using the on-track/off-track method is a moderately accurate and specific, but insensitive technique to predict surgical failure after arthroscopic capsulolabral repair for shoulder instability

OBJECTIVE. The article reviews a select group of traumatic upper extremity injuries that can be easily misinterpreted on radiographs. CONCLUSION. The awareness of these specific injuries and an understanding of their underlying pathophysiology and the role that radiographs can play in their evaluation will give the reader the best opportunity to make the important imaging findings and guide appropriate treatment.