Faculty Bibliography

Osteoarthritis (OA) is the most common joint disease in the United States. The prevalence of OA is rising due to an aging population and increasing rates of obesity. Magnetic resonance imaging (MRI) allows an incomparable noninvasive assessment of all joint structures. Irreversible and progressive degradation of the articular cartilage remains the hallmark feature of OA. To date, attempts at developing disease-modifying drugs or biomechanical interventions for treating OA have proven unsuccessful. MRI-based cartilage imaging techniques have continued to advance, however, and will likely play a central role in the development of these joint preservation methods of the future. In this narrative review, we describe clinical MR image acquisition and assessment of cartilage. We discuss the semiquantitative cartilage scoring methods used in research. Lastly, we review the quantitative MRI techniques that allow assessment of changes in the biochemical composition of cartilage, even before the morphological changes are evident.

Background The MRI manifestations of subspine impingement (SSI) other than morphologic features of anterior inferior iliac spine (AIIS) have not been extensively explored and validated. Purpose To determine the MRI findings associated with SSI, including AIIS morphologic features, femoral distal cam, and associated soft-tissue injuries. Materials and Methods This is a retrospective study of symptomatic patients who underwent arthroscopic treatment for femoroacetabular impingement between December 2014 and March 2017, with preoperative MRI within 6 months before surgery. The SSI group included patients with clinical and intraoperative findings of SSI; the remaining patients comprised the non-SSI group. Preoperative MRI findings were independently assessed by two radiologists who were blinded to clinical information. Interreader agreement was assessed, and multivariable logistic regression was also used. Results A total of 62 patients (mean age ± standard deviation, 42.1 years ± 11.9; 38 women) were included. SSI was diagnosed in 20 of the 62 patients (32%) (mean age, 43 years ± 12); 42 patients (68%) did not have SSI (mean age, 41 years ± 10). Reader 1 detected distal cam in 16 of the 20 patients with SSI (80%) and eight of the 42 patients without SSI (19%), and reader 2 detected distal cam in 15 of the 20 patients with SSI (75%) and eight of the 42 patients without SSI (19%) (P < .001 for both). Reader 1 detected signs of impingement on the distal femoral neck (IDFN) in 18 of the 20 patients with SSI (90%) and seven of the 42 patients without SSI (16%), and reader 2 detected signs of IDFN in 13 of the 20 patients with SSI (65%) and nine of the 42 patients without SSI (21%) (P < .001 and P = .001, respectively). Reader 1 detected superior capsular edema in 15 of 20 patients with SSI (75%) and three of 42 patients without SSI (7%), and reader 2 detected superior capsular edema in 17 of 20 patients with SSI (85%) and 22 of 42 patients without SSI (52%) (P < .001 and P = .02, respectively). Distal cam was a predictor of SSI after adjustment for IDFN. Interreader agreement was substantial for distal cam (κ = 0.80) and moderate for IDFN (κ = 0.50). Conclusion Soft-tissue injuries and osseous findings other than morphologic features of the anterior inferior iliac spine were associated with subspine impingement. © RSNA, 2019 See also the editorial by Guermazi in this issue.

PURPOSE/OBJECTIVE:To compare femoroacetabular motion in a series of consecutive symptomatic patients with hip pain throughout the range of motion of the hip using a real-time radial gradient echo (GRE) sequence in addition to the routine hip protocol sequences for magnetic resonance (MR) arthrographic assessment of patients with and without clinical femoroacetabular impingement (FAI) syndrome. In particular, we sought to assess whether the additional dynamic sequence could differentiate between patients with and without a positive physical exam maneuver for FAI syndrome. METHODS:Patients with hip pain referred for conventional hip MR arthrogram including those with and without a positive physical exam maneuver for FAI syndrome were imaged using routine hip MR arthrogram protocol and an additional real-time radial 2-dimensional GRE acquisition at 3 Tesla in an axial oblique plane with continuous scanning of a 9 mm thick slice through the center of the femoral head-neck axis. Patients who were unable to move through the range of motion were excluded (n = 3). Patients with acetabular dysplasia (defined by a lateral center-edge angle [CEA] of 20°) were also excluded, as were patients had Kellgren and Lawrence scores of > 0. The real-time cine sequence was acquired with the patient actively moving through neutral, flexion, flexion-abduction external-rotation, and flexion-adduction internal rotation (FADIR) positions aiming for 40° of abduction, then 25° of adduction at 80° to 90° flexion. Due to the placement of the coil over the hip, a true FADIR was precluded. Images were evaluated independently by 2 musculoskeletal radiologists measuring the joint space in the anterior, central, and posterior positions at each point during range of motion for femoroacetabular cortical space (FACS). Anterior FACS narrowing was calculated as the ratio of joint space in FADIR:neutral position, with lower ratios indicating greater narrowing. Static metrics including alpha angle, CEA, grade of cartilage loss according the Outerbridge classification, and patient demographics were also recorded. RESULTS:Twenty-two painful hips in 22 patients (11 males and 11 females) with mean age 36 years (range, 15-67) were included. Twelve patients had a positive physical exam maneuver for FAI syndrome. The time to perform the dynamic sequence was 3 to 6 minutes. Interobserver agreement was strong, with intraclass correlation 0.91 and concordance correlation 0.90. According to results from both readers, patients with impingement on clinical exam had significantly lower anterior FACS ratios compared with those without clinical impingement (reader 1: 0.39 ± 0.10 vs 0.69 ± 0.20, P = .001; reader 2: 0.36 ± 0.07 vs 0.70 ± 0.17, P < .001). Decreased anterior FACS ratio was found to be significantly correlated to increased alpha angle by both readers (reader 1: R = -0.63, P = .002; reader 2: R = -0.67, P = .001) but not significantly correlated to CEA (reader 1: R = 0.13, P = .561; reader 2: R = 0.20, P = .378) or cartilage loss (reader 1: R = 0.03, P = .885; reader 2: R = -0.06, P = .784). Both readers found patients with an anterior FACS ratio of 1/2 to have significantly higher mean alpha angle (reader 1: 62.88 vs 52.79, P = .038; reader 2: 63.50 vs 50.58, P = .006); however, there were no significant differences in cartilage loss (reader 1: P = .133; reader 2: P = .882) or CEA (reader 1: P = .340; reader 2: P = .307). CONCLUSIONS:A dynamic radial 2-dimensional-GRE sequence can be added to standard hip MR arthrogram protocols in <6 minutes, allowing assessment of dynamic femoroacetabular motion with strong interreader agreement. Patients with impingement on clinical exam had significantly lower anterior FACS ratios between FADIR and neutral positions, compared with those without clinical impingement. LEVEL OF EVIDENCE/METHODS:Level III, comparative diagnostic investigation.

Scapulothoracic pain is a common ailment, but the underlying cause can be difficult to diagnose in a timely manner, and treatment options are limited. We retrospectively review our experience using ultrasound-guided therapeutic scapulothoracic interval steroid injections to treat scapulothoracic pain and review correlative magnetic resonance imaging findings over a 5-year period. Although a variety of structural causes are known to cause scapulothoracic pain, in our experience, most cases lack correlative imaging findings. Ultrasound-guided scapulothoracic interval injections provide a safe, easily performed diagnostic and therapeutic tool for treating patients with periscapular pain, providing at least short-term symptom relief.

Piriformis syndrome is a common cause of lumbar, gluteal, and thigh pain, frequently associated with sciatic nerve symptoms. Potential etiologies include muscle injury or chronic muscle stretching associated with gait disturbances. There is a common pathological end pathway involving hypertrophy, spasm, contracture, inflammation, and scarring of the piriformis muscle, leading to impingement of the sciatic nerve. Ultrasound-guided piriformis injections are frequently used in the treatment of these pain syndromes, with most of the published literature describing injection of the muscle. We describe a safe, effective ultrasound-guided injection technique for the treatment of piriformis syndrome using targeted sciatic perineural hydrodissection followed by therapeutic corticosteroid injection.

OBJECTIVE:To evaluate change in patient-reported outcomes following image-guided intra-articular therapeutic steroid hip injections for pain and assess correlations of outcomes with patient- and injection-specific factors. MATERIALS AND METHODS/METHODS:We retrospectively reviewed consecutive patients treated for hip pain who completed outcomes assessments from October 2011 to September 2017 at an outpatient orthopedic surgery clinic. Only patients with radiographic hip osteoarthritis (Tönnis grade ≥ 1) who underwent steroid hip injections were included. Outcomes assessments included EuroQol-5 domain (EQ5D), EQ5D-visual analog scale (VAS), and hip disability and osteoarthritis outcome score (HOOS), obtained before and within 1-6 months post-injection. Among 113 patients who completed surveys, the mean age was 59 years (±13.7 years), including 77 women (68%) and 36 men (32%). Time to repeat injection or arthroplasty was recorded. Exact Wilcoxon signed rank test assessed score differences and Spearman correlation, Kruskal-Wallis, and Mann-Whitney tests assessed correlations. RESULTS:Of 113 patients, 34 had outcomes measured at <8 weeks and 79 at ≥8 weeks. There was no significant change among any of the patients, short- or long-term follow-up subgroups in EQ5D (p = 0.450, 0.770, 0.493 respectively), EQ5D-VAS (p = 0.581, 0.915, 0.455), average-HOOS (p = 0.478, 0.696, 0.443) or total-HOOS (p = 0.380, 0.517, 0.423) scores. Forty-nine patients underwent hip arthroplasty within 1 year. Positive correlation was found between days from injection to surgery and change in EQ5D (r = 0.29, p = 0.025), average-HOOS (r = 0.33, p = 0.019), and total-HOOS (r = 0.37, p = 0.008). CONCLUSION/CONCLUSIONS:We demonstrated no significant change in patient-reported outcomes measured at short- and long-term intervals up to 6 months after therapeutic steroid hip injections.

OBJECTIVE:The purpose of this study is to determine the most accurate imaging techniques to measure glenoid bone loss in anterior glenohumeral instability through a systematic review of existing literature. MATERIALS AND METHODS/METHODS:We performed a comprehensive literature search of five databases for original research measuring glenoid bone loss at radiography, CT, or MRI, using prospective or retrospective cohort, case-control, or cadaveric study designs up to January 2018. The Quality Assessment of Diagnostic Accuracy Studies-2 tool aided qualitative assessment of the methods. Data extraction included results, index test interobserver agreement, and accuracy analysis. RESULTS:Twenty-seven studies (evaluating 1425 shoulders) met inclusion criteria after full-text review by two independent readers. Glenoid bone loss was assessed, comparing several index tests to nonimaging (n = 18 studies) and imaging (n = 11) reference standards. Compared with arthroscopic or cadaveric measurements, 2D CT was accurate in six of seven studies (86%), 3D CT was accurate in eight of 10 studies (80%), 2D MRI was accurate in five of seven studies (71%), 3D MRI was accurate in four of four studies (100%), and radiographs were accurate in zero of four studies (0%). Best-fit circle methods (glenoid width or Pico surface area) were the most common and both were accurate (86-90% and 75-100%, respectively) using CT and MRI. Studies had good external validity (78%). Most risk for bias arose from patient selection and reference standards. Only two studies reported sensitivity and specificity, both comparing CT to arthroscopy using different bone loss thresholds (20% and 25%). CONCLUSION/CONCLUSIONS:CT and MRI (2D or 3D) accurately measure glenoid bone loss in anterior shoulder instability, but radiographs do not. Best-fit circle measurement techniques are reliable and accurate. Current literature about glenoid bone loss is heterogeneous, and future studies should focus on diagnosis of clinically relevant glenoid bone loss.

Purpose: To explore variation in downstream costs associated with cartilage lesions incidentally detected on radiographs. Materials andMethods: The cohort was composed of 120 patients with incidental, not previously diagnosed, cartilage lesions seen on appendicular plain radiographs. The population was divided into three subgroups based on the interpreting radiologist's description: enchondroma, lowgrade cartilage lesion, and chondrosarcoma. Downstream events (follow-up imaging, office visits, biopsy, tumor resection) associated with the lesions were identified from the electronic medical record. American College of Radiology (ACR) Appropriateness Criteria were used to classify radiologists' recommendations. NationalMedicare rates were used to estimate costs of downstream events. Average cost per lesion was stratified, and cost ratios were computed among subgroups.
Result(s): Average downstream cost per lesion was $75.56. Costs were 4.6 times greater in patients under the age of 65 than over. Costs were 13.2 and 13.7 times higher when radiologists characterized lesions as chondrosarcoma versus low-grade cartilage lesion and enchondroma, respectively. There was no statistically significant difference in costs between the subgroups when accounting for size and location of lesions. Compared to when follow-up imaging was neither recommended nor obtained, costs rose from $0 to $26.03 per patient when follow-up imaging was recommended and obtained, and $62.21 per patient when followup imaging was obtained despite not being recommended. Costs rose from $0 to $14.83 per patient when radiologists' recommendations for follow-up were adherent to the ACR guidelines for management of incidental bone lesions. Costs were 2.3 times greater when ordering physicians overmanaged compared with radiologists' recommendations. No malignancy was pathologically proven in the cohort.
Conclusion(s): Costs for incidental cartilage lesions vary. Size and location of lesions do not have a significant effect on downstream costs; however, radiologists' characterization and recommendation have an impact. Therefore, it is imperative that radiologists accurately characterize such lesions and recommendations reflect the best value for patient care

OBJECTIVE:The purpose of this study was to describe clinical experience with ultrasound-guided therapeutic procedures and associated pathologic conditions involving the peripheral nerves of the upper extremity over 5 years at a large academic institution. MATERIALS AND METHODS/METHODS:A retrospective database search of procedure codes was performed for all ultrasound-guided upper extremity peripheral nerve procedures between 2012 and 2017. Retrospective review of the electronic medical record for patient demographics, indications, interval follow-up pain relief, and complications was undertaken. Retrospective review of ultrasound and other correlative imaging findings was performed to assess for neural and perineural abnormalities. RESULTS:In total, 242 procedures performed on a cohort of 183 patients (53% women, 47% men; mean age, 53 years; range, 15-97 years) were reviewed. Nine patients underwent multifocal injections in a single encounter, and 39 underwent repeat injections of previously documented symptom generators. Perineural injections included ulnar (n = 109), median (n = 81), posterior interosseous-deep radial (n = 39), sensory branch of the radial (n = 7), anterior interosseous (n = 2), axillary (n = 2), suprascapular (n = 1), and digital (n = 1) nerves. Structural or dynamic abnormality seen either during the procedure or at preprocedural imaging included loss of normal morphologic features (n = 148), nerve subluxation (n = 8), ganglion cyst (n = 4), and neuroma (n = 7). Forty-four patients reported immediate pain relief after the procedure. Of the 89 patients with documented clinical follow-up, 52 reported a period of symptom relief (mean, 125 days), and six reported complete resolution of symptoms. Subsequent surgical procedures were performed on 32 patients, a combination of those who did (n = 12) and did not (n = 20) experience a period of symptom relief from the perineural injection. There were no complications with regard to the site or distribution of perineural injections. Three episodes of vasovagal reaction were reported. CONCLUSION/CONCLUSIONS:Ultrasound-guided percutaneous interventions for upper extremity neural abnormalities can be safely performed for a variety of indications. Real-time ultra-sound evaluation during the procedure allows assessment for neural and perineural abnormalities and tailoring of the procedure to potentially symptomatic structural abnormalities.

The midtarsal (Chopart) joint complex consists of the talonavicular and calcaneocuboid joints and their stabilizing ligaments. Detailed assessment of this complex at MRI can be challenging owing to frequent anatomic variation and the small size of the structures involved. Nevertheless, a wide spectrum of pathologic conditions affect the joint complex, and its imaging evaluation deserves more thorough consideration. This review focuses on MRI evaluation of normal ligamentous anatomy and common variations about the Chopart joint, presenting practical imaging tips and potential diagnostic pitfalls. Imaging findings across a spectrum of traumatic Chopart joint injuries are also reviewed, from midtarsal sprains to Chopart fracture-dislocations. Midtarsal sprains-commonly associated with ankle inversion injuries-are emphasized, along with their often predictable radiographic and MRI injury patterns. Online DICOM image stacks are available for this article. ^©RSNA, 2018.