Ultrasound assessment of synovitis in total knee replacements: concordance with MR imaging and joint aspiration.

OBJECTIVE: To determine if diagnostic ultrasound can reliably distinguish between synovial patterns of prosthetic joint infection and polymeric wear in total knee replacements. METHODS AND METHODS: This retrospective study was approved by our hospital IRB. Using the radiology report database, MR examinations performed within a week of diagnostic ultrasound and/or ultrasound-guided aspiration were identified. This yielded (1) 24 cases with MR and ultrasound comparisons; (2) 44 cases with MR, ultrasound, and aspiration comparisons; and (3) 92 cases with ultrasound and aspiration comparisons. The MR studies were reviewed by a musculoskeletal radiologist. The ultrasound studies were each reviewed by 2 other musculoskeletal radiologists. Each study was graded for synovial pattern indicating infection, polymeric wear, or normal/nonspecific. Agreement between the MR grader and the ultrasound graders as well as ultrasound inter-rater agreement were assessed using k statistics. Sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound were calculated. RESULTS: Agreement between ultrasound and MR imaging was fair to moderate: k of 0.27 (95% CI: 0.04, 0.50) and 0.44 (95% CI: 0.23, 0.65) for ultrasound raters 1 and 2, respectively. Inter-rater agreement between ultrasound graders 1 and 2 was moderate, with k of 0.56 (95% CI: 0.42, 0.70). Ultrasound sensitivities for infection were 0.13 and 0.09, while specificities were 0.94 and 0.98. Ultrasound sensitivities for polymeric wear were 0.38 and 0.62 with specificities of 0.90 and 0.76. CONCLUSION: Ultrasound does not perform well in distinguishing patterns of synovitis either compared to MRI or a reference standard of aspiration/clinical follow-up.

MR Neurography and Quantitative Muscle MRI of Parsonage Turner Syndrome Involving the Long Thoracic Nerve.

BACKGROUND: Parsonage-Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass-like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes. PURPOSE/HYPOTHESIS: 1) To characterize qMRI findings in LTN-involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG). STUDY TYPE: Prospective. POPULATION: 30 PTS subjects (25 M/5 F, mean/range age = 39/15-67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN. FIELD STRENGTH/SEQUENCES: 3.0 Tesla/multiecho spin-echo T2-mapping, diffusion-weighted echo-planar-imaging, multiecho gradient echo. ASSESSMENT: qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross-sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI. STATISTICAL TESTS: Paired t-tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG. RESULTS: Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 µm) and cross-sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm2 ). There were weak to negligible associations (tau = -0.229 to <0.001, P = 0.054-1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG. DATA CONCLUSION: qMRI changes in the SAM were observed in subjects with PTS involving the LTN. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.

Diagnostic ultrasound of tendon injuries in the setting of distal radius fractures.

OBJECTIVE: Describe tendon injuries and their structural causes seen on ultrasound in wrists with distal radius fractures and estimate the accuracy of ultrasound and its impact on clinical management. MATERIALS AND METHODS: Ultrasounds of 226 wrists (221 patients) with distal radius fractures were retrospectively reviewed. Ultrasound findings of tendon injuries and their structural causes were correlated with surgery and clinical outcome. Accuracy and inter- and intra-observer reproducibilities were calculated. RESULTS: Twenty-five wrists were treated non-operatively while 201 underwent surgery. Ultrasound demonstrated hardware contact with flexor pollicis longus (FPL) in 76 wrists, extensor pollicis longus (EPL) in 21, and other tendons in 94. Ultrasound identified tendon ruptures in 23 wrists (13 EPL/8 FPL/2 extensor indicis proprius (EIP)), most of which were surgically confirmed. Among 12 wrists with confirmed EPL ruptures, distal radius fracture had been treated with volar plating in 6 and non-operatively in 6, and ultrasound showed osseous irregularity at the rupture site in 8. All FPL ruptures occurred in wrists with volar plating. Ultrasound findings were concordant with subsequent clinical management in most. In 2, ultrasound findings led to the decision to remove hardware despite lack of symptoms. Ultrasound had sensitivity/specificity/accuracy of 88/99/98% for identifying a specific tendon as ruptured and 88/87/88% for tendon abnormalities in general. Inter- and intra-observer reproducibilities were excellent (kappa = 0.85 ~ 1.0). CONCLUSION: Certain wrist tendons, particularly EPL and FPL, are vulnerable after distal radius fractures. Ultrasound is accurate and useful for detecting tendon injury and sources of tendon irritation and can guide clinical management.

Ferumoxytol-enhanced vascular suppression in magnetic resonance neurography.

OBJECTIVE: To evaluate ferumoxytol-enhanced vascular suppression for visualizing branch nerves of the brachial plexus in magnetic resonance (MR) neurography. MATERIALS AND METHODS: Signal simulations were performed to determine ferumoxytol's effect on nerve-, fat-, and blood-to-muscle contrast and to optimize pulse sequence parameters. Prospective, in vivo assessment included 10 subjects with chronic anemia who underwent a total of 19 (9 bilateral) pre- and post-infusion brachial plexus exams using three-dimensional (3D), T2-weighted short-tau inversion recovery (T2-STIR) sequences at 3.0 T. Two musculoskeletal radiologists qualitatively rated sequences for the degree of vascular suppression and brachial plexus branch nerve conspicuity. Nerve-to-muscle, -fat, and -vessel contrast ratios were measured. RESULTS: Quantitative nerve/muscle and nerve/small vessel contrast ratios (CRs) increased with ferumoxytol (p < 0.05). Qualitative vascular suppression and suprascapular nerve visualization improved following ferumoxytol administration for both raters (p < .05). Pre- and post-ferumoxytol exams demonstrated moderate to near-perfect inter-rater agreement for nerve visualization and diagnostic confidence for the suprascapular and axillary nerves but poor to no agreement for the long thoracic nerve. CONCLUSION: Ferumoxytol in T2-weighted brachial plexus MR neurography provides robust vascular suppression and aids visualization of the suprascapular nerve in volunteers without neuropathy.

Ultrasound-guided aspiration of anterior cruciate ligament mucinous cysts in the posterior intercondylar notch: Technique and short-term outcomes.

PURPOSE: To describe our technique of aspirating symptomatic anterior cruciate ligament (ACL) mucinous cysts in the posterior intercondylar notch with ultrasound guidance, and to detail short-term patient outcomes. METHODS: We identified 13 patients from February 2008 to May 2020 who underwent ultrasound-guided aspiration of symptomatic ACL mucinous cysts in the posterior intercondylar notch. Post-procedural imaging was reviewed to evaluate the degree of cyst decompression. Needle size was noted. Post-procedural symptomatology was also assessed. RESULTS: No or minimal fluid was initially aspirated in 11/13 (84.6%) patients. For the two patients in which the cysts were aspirated completely with initial needle placement, with no need for lavage, a 13-gauge trocar was utilized. Of the remaining cysts, 10/11 were aspirated with an 18-gauge needle and one with a 20-gauge needle. Subsequent lavage was performed in 10 of the remaining 11 patients. After lavage, in eight there was a reduction of at least 50% volume by retrospective image interpretation; of 25% to 50% volume in one patient and of less than 25% volume in one patient. Five of the 13 patients reported immediate post-procedural symptomatic relief. In the other patients, immediate efficacy or post-procedural symptomatology was not documented. CONCLUSION: Aspiration of symptomatic ACL mucinous cysts is a safe procedure and can provide symptomatic relief that may be temporary, but useful clinically. We recommend needles larger than 18 gauge for the best chance of successful aspiration.

Ultrasound-Guided Biceps Tendon Sheath Injection: Spectrum of Preprocedure Appearances.

OBJECTIVES: To determine the frequency of ultrasound (US) appearances of the extra-articular long head of the proximal biceps tendon in patients referred for US-guided biceps tendon sheath injections. METHODS: We reviewed our US-guided biceps tendon sheath injections between January 2015 and December 2017, noting the appearance of the biceps tendon and sheath, as well as the needle size used, and what was injected. Clinical electronic medical records were also reviewed to determine safety and patients' responses. RESULTS: A total of 300 US-guided biceps tendon sheath injections were performed for anterior shoulder pain. Preliminary US evaluations revealed that 129 of 300 (43%) patients had a normal US appearance of the biceps tendon; 110 (36.6%) had tendinosis; 13 (4.3%) had tenosynovitis; 31 (10.3%) had both tendinosis and tenosynovitis; 8 (2.7%) had a biceps tendon tear; and 9 (3%) had a history of a tenodesis. Of 81 patients who had pain relief after the injection, 41 had a normal tendon appearance on US, and 40 had an abnormal US appearance. CONCLUSIONS: A large minority of patients with anterior shoulder pain clinically suspected to be due to the biceps tendon have a normal-appearing tendon and sheath. This should not dissuade the operator from performing the procedure.

Imaging evaluation of polyethylene liner dissociation in total hip arthroplasty.

OBJECTIVE: To describe the imaging findings of polyethylene liner dissociation in total hip arthroplasty. MATERIALS AND METHODS: Retrospective search of our institution's radiology database identified 12 patients with polyethylene liner dissociation of a total hip arthroplasty. Clinical and operative notes were reviewed. All radiological studies were reviewed independently by two radiologists. RESULTS: Among 12 patients (seven females/five males; mean age: 67 years; median interval after surgery at diagnosis: 8.5 months) with polyethylene liner dissociation, 11 had radiographs, six had CT, seven had MRI, and two had arthrography. "Bubble sign" and "crescent sign" on radiography were insensitive, seen only in three patients, but all showed abrupt eccentric positioning of the femoral head. CT identified the dislocated liner in five of six patients but failed to identify one liner, which was partially associated with the acetabular cup. MRI identified the dislocated liner in all seven patients, with the MAVRIC (multiacquisition variable resonance image combination) sequences either increasing the diagnostic confidence relative to the routine pulse sequences or being the sole sequences in which the liner can be identified if the liner remained partially associated with the acetabular cup. Arthrography identified the dislocated liner in one of two patients. CONCLUSIONS: Previously described radiographic signs of polyethylene liner dissociation are insensitive, but abrupt eccentric positioning of the femoral head in the correct clinical context is highly suggestive of the diagnosis. MRI and CT can accurately localize the displaced liner. MAVRIC is particularly helpful if the dislocated liner remains partially associated with the acetabular cup.

Ultrasound Diagnosis of Osteophytic Impingement of the Popliteus Tendon After Total Knee Replacement.

We report our experience with 6 patients who had total knee replacements with lateral-sided knee pain, referred for ultrasound (US) assessment and US-guided injection. All cases showed an osteophyte within the popliteus sulcus of the lateral femoral condyle impinging on the adjacent tendon. Five of 6 patients reported improvement of symptoms immediately after US-guided injection of an anesthetic and a steroid. Ultrasound has a unique role in the imaging of knee replacements because of its real-time capabilities and absence of artifacts at the popliteus tendon origin.

Rhabdomyolysis resulting in concurrent Horner's syndrome and brachial plexopathy: a case report.

This case report describes a 29-year-old male who presented with immediate onset of Horner's syndrome and ipsilateral brachial plexopathy after sleeping with his arm dangling outside a car window for 8 h. Outside workup and imaging revealed rhabdomyolysis of the left neck musculature. Subsequent electrodiagnostic testing and high-resolution brachial plexus magnetic resonance imaging at the authors' institution attributed the Horner's syndrome and concurrent brachial plexopathy to rhabdomyolysis of the longus colli and scalene musculature, which had compressed-and consequently scar tethered-the cervical sympathetic trunk and brachial plexus. This case of co-existent Horner's syndrome and brachial plexopathy demonstrates the role of high-resolution brachial plexus MRI in diagnosing plexopathy and the importance of being familiar with plexus and paravertebral muscle anatomy.

Sonographic evaluation of patellar clunk syndrome following total knee arthroplasty.

Patellar clunk syndrome is a painful mechanical phenomenon that may develop following total knee arthroplasty. The diagnosis is usually made clinically, but cross-sectional imaging may be needed to confirm the clinical suspicion. Sonographic confirmation of patellar clunk syndrome can be obtained by directly visualizing the soft tissue proliferation deep to the distal quadriceps tendon and by dynamically demonstrating the clunking tissue during flexion and extension of the knee. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:105-107, 2017.

Comparison of navigated versus non-navigated pedicle screw placement in 260 patients and 1434 screws: screw accuracy, screw size, and the complexity of surgery.

OBJECTIVE: Computer 3D navigation (3D NAV) techniques in spinal instrumentation can theoretically improve screw placement accuracy and reduce injury to critical neurovascular structures, especially in complex cases. In this series, we analyze the results of 3D NAV in pedicle screw placement accuracy, screw outer diameter, and case complexity in comparison with screws placed with conventional lateral fluoroscopy. METHODS: Pedicle screws placed in the cervical, thoracic, or lumbar spine using either standard lateral fluoroscopy or 3D NAV using isocentric fluoroscopy were retrospectively analyzed. The accuracy of each individual screw was graded on a 4-tiered classification system. Screw and pedicle diameter measurements were also made in both cohorts, and case complexity was compared between the 2 cohorts. Complex cases were defined as deformity surgery, re-do cases, and minimally invasive surgery. RESULTS: A total of 708 screws were placed under 3D NAV guidance and 726 screws were placed without stereotaxy. Eighty-eight percent of 3D NAV-guided pedicle screws were graded nonbreach versus 82% of cases with lateral fluoroscopy (P<0.001). The ratio of screw/pedicle diameter was significantly larger in the 3D NAV cohort (0.71 vs. 0.63, P<0.05). Seventy-six percent of 3D NAV cases had a predefined aspect of complexity, whereas 44% of non-3D NAV cases met criteria to be labeled complex (P<0.001). Reoperation occurred less frequently in 3D NAV cases than fluoroscopy alone. CONCLUSIONS: The use of 3D NAV was associated with improved screw placement accuracy, improved screw-to-pedicle diameter measurements, and was used in cases with a higher degree of surgical complexity. We conclude that 3D NAV is a valuable tool in current spinal instrumentation, especially for more complex surgeries.

Outcomes of ultrasound-guided injections of Bennett lesions of the shoulder.

PURPOSE: To describe our technique and short term follow up of ultrasound-guided injections of symptomatic Bennett lesions. METHODS: We performed 13 ultrasound-guided injections in 10 baseball players from August 2014 to August 2021. The cohort was comprised of 10 males, with a mean age of 25 years and 1 month (age range: 17 years, 10 months-33 years, 1 month). Of the 10 patients, 6 were major league baseball players (including 5 pitchers and a second baseman), 3 were minor league baseball pitchers; and 1 pitched in high school. Symptoms in our patients included posterior shoulder pain at rest, pain with pitching (including in the acceleration phase and with follow-through), glenoid internal reduction deficit, and decreased pitching velocity. The procedure was performed in a similar fashion as a standard posterior approach glenohumeral injection, though with the linear transducer positioned slightly more medially. The needle was inserted from a lateral to medial approach, in plane with the transducer and aimed to the superficial surface of the Bennett lesion, onto which anesthetic and steroid was injected, avoiding injection into the glenohumeral joint. RESULTS: All patients had MRIs that showed Bennett lesions and all but one of the sonograms demonstrated the Bennett lesion. In 8/12 (67%) injections, the patient reported varying degrees of immediate symptom relief. In 4/12 injections, patients were unable to assess for immediate postprocedural change in symptomatology and for one patient post-procedural symptomatology was not documented. No complications occurred. Analytics of the average 4-seam fastball velocity was available for 2 of the major league players who had in-season injections, with minimal change in postprocedural velocity in the year after their ultrasound procedure; for one of the pitchers, his fastball velocity slightly increased in the month after the procedure while the other pitcher had his injection towards the end of the season and he threw no fastballs in his final games of the season. Two of the other professional pitchers went on to surgical intervention and neither returned to pitch professionally. CONCLUSION: Injection of symptomatic Bennett lesions is a safe procedure and can provide symptomatic relief that may be temporary, though equivocally useful clinically.

Serial Ultrasonography for the Assessment of Healing of Lower Extremity Bone Stress Injury and Correlation With Return to Sport/Exercise.

BACKGROUND: Lower extremity bone stress injuries (BSIs) are common among athletes who participate in high-impact activities. Conventional imaging is limited in assessing healing of BSIs. HYPOTHESIS: Serial ultrasonography (US) can identify changes in appearance of lower extremity BSIs over time that can be correlated with symptoms and return to exercise/sport. STUDY DESIGN: Cohort observational study. LEVEL OF EVIDENCE: Level 3. METHODS: Adults 18 to 50 years old with a recent exercise-associated BSI of distal tibia/fibula or metatarsals diagnosed by magnetic resonance imaging (MRI) were enrolled. US was performed every 2 weeks for 12 weeks. The sonographic appearance (soft tissue edema, periosteal reaction, hyperemia on power Doppler, callus) was correlated with the numerical rating scale (NRS) for pain and ability to return to sport/exercise. RESULTS: A total of 30 patients were enrolled (mean age, 35.3 ± 7.7 years; 21 [70.0%] female). The tibia was most frequently affected (n = 15, 50.0%), followed by metatarsals (n = 14, 46.7%) and fibula (n = 1, 3.3%). At week 4, 25 of 30 (83.3%) had at least 1 US finding associated with the BSI. The degree of hyperemia was correlated with NRS at weeks 4 and 6 (Spearman correlations [ρ] 0.45 [0.09, 0.69] and 0.42 [0.07, 0.67], respectively), as well as return to sport/exercise at week 6 (ρ -0.45 [-0.68, -0.09]). US soft tissue edema was also correlated with NRS at week 6 (ρ 0.38 [0.02, 0.65]). CONCLUSION: Serial US of lower extremity BSIs can provide objective measures of healing. US findings were correlated with clinical outcomes at multiple timepoints. CLINICAL RELEVANCE: US may have advantages over conventional imaging for monitoring healing of lower extremity BSIs. Further research is needed to better understand the prognostic value of these sonographic indicators of BSI healing and role in assessing readiness for return to sport/exercise.

Osteomyelitis and septic arthritis after Mycobacterium Bovis BCG Therapy for Urinary Bladder Cancer.

Mycobacterium bovis (M. bovis) Bacillus Calmette-Guerin (BCG) - an attenuated strain of M. bovis - is closely related to Mycobacterium tuberculosis and may be used as a vaccine against tuberculosis as well as a treatment for urinary bladder cancer. Complications of M. bovis BCG administration, while rare, can occur. While a few cases of vertebral osteomyelitis secondary to BCG therapy exist in the literature, and while there are case reports of osteomyelitis and septic arthritis from BCG vaccination (Chen et al., 2017; Huang et al., 2019; Lin et al., 2015 [1-3]), there are no reported cases of osteomyelitis and septic arthritis involving the foot from BCG therapy for urinary bladder cancer. We present an unusual presentation of osteomyelitis and septic arthritis of the tarsometatarsal joints after M. bovis BCG therapy for urinary bladder cancer. We will describe MRI and ultrasound findings in our case of M. bovis BCG osteomyelitis and septic arthritis.

Etiology of Lumbosacral Radiculoplexopathy: Sacral Insufficiency Fracture on Magnetic Resonance Imaging.

BACKGROUND: Sacral insufficiency fracture (SIF) can cause lumbosacral radiculoplexopathy (LSRP) and is probably under-recognized. Symptoms may include nonspecific lumbar spine or buttock pain that is exacerbated by physical activity and alleviated with rest. The frequency of LSRP secondary to SIF has not been reported. QUESTIONS/PURPOSES: We aimed to determine the frequency of LSRP associated with SIF using magnetic resonance imaging (MRI) of the lumbar spine. METHODS: We searched a radiology database at our institution using the keywords "sacral insufficiency fracture" and "lumbar spine MRI" for patient records from January 2014 through December 2017. We assessed for the presence of LSRP, reflected by elevated T2-weighted or short tau inversion recovery (STIR) signal intensity and enlargement of the nerve on noncontrast lumbar spine MRI. An incompletely healed vertically oriented SIF was confirmed if there was a persistent bone marrow edema pattern adjacent to the fracture site; we did not include purely transverse SIFs. The final cohort comprised 57 patients (48 female; age range, 14 to 89 years). RESULTS: Abnormalities of the extraforaminal L5 nerve root or the combined L4 and L5 nerve roots (the lumbosacral trunk) were identified in 19 (33%) of 57 patients, with a total of 23 sites (bilateral involvement in four cases). Of the 23 abnormal nerves, 19 (82.6%) had corresponding, clinically documented radicular symptoms and 16 (69.6%) had no other explanation on MRI for their radicular symptoms other than SIF. CONCLUSIONS: LSRP caused by SIF is an entity all radiologists should be cognizant of, especially in cases of otherwise unexplained radicular symptoms. The diagnosis of SIF can be helpful in cases involving concomitant multilevel lumbar spondylosis and neural foraminal stenosis.

Identification of long thoracic nerve on high-resolution 3T MRI.

OBJECTIVE: Long thoracic neuropathy results in serratus anterior muscle denervation and presents with scapular winging. Previously published studies have been unable to identify the long thoracic nerve on MRI; instead, secondary imaging features of serratus anterior muscle denervation are used to infer nerve injury. Our study's purpose was to evaluate the ability of high-resolution MRI to depict the long thoracic nerve. MATERIALS AND METHODS: In this HIPAA-compliant, IRB-approved retrospective study, two musculoskeletal radiologists reviewed the brachial plexus MRI exans of 24 subjects performed for clinical suspicion of long thoracic neuropathy. The radiologists evaluated whether the long thoracic nerve could be identified and for the presence of serratus anterior denervation; when the nerve was seen, assessment for nerve enlargement, signal hyperintensity, and morphologic change was performed. Inter-observer reliability was estimated with Cohen's kappa (κ). Clinical presentation and electromyogram (EMG) were then reviewed. RESULTS: The long thoracic nerve was identified in 18 cases (75%), with high inter-observer reliability for nerve visualization. Kappa values of 1.0, 0.9, 1.0, and 0.9 were obtained for identification of the LTN on coronal sequences of the brachial plexus, identification of the LTN on proximal and mid segments of the nerve on oblique sagittal sequences, and identification of the distal segment of the LTN on axial sequences through the chest, respectively. The nerve was identified in 91% of patients with positive EMG findings for a long thoracic neuropathy. In patients with EMG features of long thoracic neuropathy, 70% had corresponding abnormal MRI features. When denervation edema was present, the nerve was identified 86% of the time. CONCLUSION: High-resolution MRI can be used to visualize segments of the long thoracic nerve.

Post-Contrast 3D Inversion Recovery Magnetic Resonance Neurography for Evaluation of Branch Nerves of the Brachial Plexus.

PURPOSE: To compare 3.0 Tesla brachial plexus three-dimensional (3D) T2-weighted short tau inversion recovery fast spin echo (STIR-FSE) MRI sequences before (pre-contrast STIR) and after (post-contrast STIR) administration of gadolinium intravenous contrast. METHOD: Eighteen patients were included. Each patient was imaged before and after intravenous contrast administration during the same session. 3D STIR-FSE sequences were obtained at 3.0 Tesla using two 16-channel flexible coils positioned over the lower neck and chest wall region. Three musculoskeletal radiologists qualitatively assessed degree of vascular signal suppression, visualization of the axillary, musculocutaneous, and suprascapular nerves, diagnostic confidence in nerve evaluation, and lesion conspicuity. Marginal ordinal logistic regression models were used to compare subjective ratings between sequences. Pre- and post-STIR lesion conspicuity was compared using Wilcoxon signed-rank test. Inter- and intra-observer agreements were assessed using Gwet's agreement coefficient. RESULTS: Vascular signal suppression significantly improved following contrast administration (odds ratio, OR = 209.9, 95% confidence interval, CI: 21.0-2094.6, p < .001). The post-contrast STIR technique significantly improved nerve visualization (OR = 8.4, 95% CI: 3.6-19.9, p < .001) and diagnostic confidence in evaluation (OR = 13.2, 95% CI: 4.8-36.0, p < .001) across all nerve segments. Post-contrast STIR improved lesion conspicuity by 1 point, but statistical significance was not reached (Reader 1: p = 0.5, Reader 2: p = 0.063). Post-contrast STIR imaging demonstrated substantial to near-perfect inter- and intra-rater agreement coefficients for both nerve visualization (inter-rater: 0.74-1.0, intra-rater: 0.94-1.0) and diagnostic confidence (inter-rater: 0.79-1.0, intra-rater: 0.94-1.0). Quantitatively, post-contrast STIR demonstrated a 24% increase in mean C6 nerve-to-muscle signal intensity ratio (p = 0.017). CONCLUSIONS: Post-contrast STIR improved nerve-to-muscle contrast ratio, allowing for enhanced visualization and diagnostic confidence in evaluation of branch nerves of the brachial plexus.

When the Wave Breaks You: Magnetic Resonance Imaging Findings After Surfing Injuries.

BACKGROUND: There are approximately 2.1 million recreational surfers in the United States. However, little has been reported on surfing-related injuries and, to date, no study has utilized magnetic resonance imaging (MRI) to characterize injury patterns. OBJECTIVE: To use MRI to perform a descriptive analysis of surfing injuries in patients who presented to an urban tertiary care musculoskeletal hospital. This was not a hypothesis-driven study. STUDY DESIGN: Case series. LEVEL OF EVIDENCE: Level 4. METHODS: A retrospective review of the picture archiving and communication system as well as the electronic medical record was performed to identify patients with surfing-related injuries who presented to a tertiary care musculoskeletal hospital for treatment. The search included participants over a 10-year period who presented between January 1, 2009, and August 1, 2018. Descriptive data analyses were performed to determine frequency of body part injured, diagnosis, and operative versus nonoperative treatment. RESULTS: The search yielded 109 patients with surfing-related injuries and MRIs. A total of 90 patients presented within 6 months of their surfing injury and were included in the final analysis. The median age was 36 years (range, 12-66 years). A majority of the patients included were male (74%; n = 67). Acute surfing injuries were diagnosed via imaging in 72% (n = 65) of patients. The joints injured most commonly were the shoulder (46%; n = 30) and the knee (28%; n = 18). Only 17% (n = 11) of acute surfing injuries required surgery, while 83% (n = 54) were treated nonoperatively. CONCLUSION: The most common surfing-related injuries occurred in the shoulder and knee. CLINICAL RELEVANCE: This study helps characterize the risk of injury for surfers and informs healthcare providers on common surfing injuries.