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Musculoskeletal neoplasms include tumors arising from bone, cartilage, muscles, tendons, nerves, and synovium. After initial screening radiographs, magnetic resonance (MR) imaging is the mainstay of management, and its role continues to increase in both pre- and post-operative evaluations. This article presents a review of the available qualitative and quantitative MR techniques for evaluating musculoskeletal neoplasms, including conventional and advanced imaging techniques such as diffusion-weighted and diffusion-tensor imaging, chemical shift and Dixon imaging, dynamic contrast-enhanced MRI, neurography, and spectroscopy. After reading the article, radiologists and oncologists will be able to apply these principles in their practices to benefit patients with musculoskeletal neoplasms.

Background Data describing the effect of obesity on antitumor necrosis factor (anti-TNF) treatment response are inconsistent. Visceral adipose tissue (VAT) is a superior marker of adiposity to body mass index. However, its effect on treatment response is unclear. We aimed to evaluate the effect of VAT on anti-TNF treatment response. Methods Inflammatory bowel disease (IBD) patients starting anti-TNF agents between January 1, 2009, and July 31, 2019, were included. 3-dimensional measurements of VAT volume and visceral fat index (visceral:subcutaneous adipose tissue ratio; VFI) were obtained from computed tomography (CT) scans. Subjects were categorized by predefined volume cutoffs ( Results The final cohort included 176 patients. No significant differences in treatment response at 6 months was observed. At 12 months, compared with volume Conclusions We found VAT volume is associated with anti-TNF treatment response in a nondose dependent manner, and VFI may inform risk of surgery after anti-TNF initiation. If confirmed by prospective studies, VAT volumetrics are potentially useful biomarkers to inform IBD treatment decisions.

As quality and cost effectiveness become essential in clinical practice, an evidence-based evaluation of the utility of imaging orders becomes an important consideration for radiology’s value in patient care. We report an institutional quality improvement project including a retrospective review of utility of sacrum magnetic resonance (MR) imaging for low back pain at our institution over a four-year period and follow-up results after physician education intervention. Sacral MR imaging for low back pain and tailbone pain were only positive for major findings in 2/98 (2%) cases, and no major changes in patient management related to imaging findings occurred over this period, resulting in almost $500000 cost without significant patient benefit. We distributed these results to the Family Medicine department and clinics that frequently placed this order. An approximately 83% drop in ordering rate occurred over the ensuing 3 mo follow-up period. Sacrum MR imaging for low back pain and tail bone pain has not been a cost-effective diagnostic tool at our institution. Physician education was a useful tool in reducing overutilization of this study, with a remarkable drop in such studies after sharing these findings with primary care physicians at the institution. In conclusion, sacrum MR imaging rarely elucidates the cause of low back/tail pain diagnosed in a primary care setting and is even less likely to result in major changes in management. The practice can be adopted in other institutions for the benefit of their patients and improve cost efficiency.

OBJECTIVE To develop and validate an Osseous Tumor Reporting and Data System (OT-RADS) with the hypothesis that the proposed guideline is reliable and assists in separating benign from malignant osseous tumors with a good area under the curve, and that could assist further patient management. METHODS In this multireader cross-sectional validation study, an agreement was reached for OT-RADS categories based on previously described magnetic resonance imaging features and consensus of expert musculoskeletal radiologists. World Health Organization classification was used, and a wide spectrum of benign and malignant osseous tumors was evaluated. Magnetic resonance imaging categories were as follows: OT-RADS 0-incomplete imaging; OT-RADS I-negative; OT-RADS II-definitely benign; OT-RADS III-probably benign; OT-RADS IV-suspicious for malignancy or indeterminate; OT-RADS V-highly suggestive of malignancy; and OT-RADS VI-known biopsy-proven malignancy or recurrent malignancy in the tumor bed. Four blinded readers categorized each tumor according to OT-RADS classification. Intraclass correlation (ICC) and Conger κ were used. Diagnostic performance measures including area under the receiver operating curve were reported. Osseous Tumor Reporting and Data System was dichotomized as benign (I-III) and malignant (IV and V) for calculating sensitivity and specificity. RESULTS Interreader agreement for OT-RADS (ICC = 0.78) and binary distinction of benign versus malignant (κ = 0.67) were good to excellent, while agreement for individual tumor feature characteristics were poor to fair (ICC = 0.25-0.36; κ = 0.16-0.39). The sensitivities, specificities, and area under the receiver operating curve of the readers ranged from 0.93-1.0, 0.71-0.86, and 0.92-0.97, respectively. CONCLUSIONS Osseous Tumor Reporting and Data System lexicon is reliable and helps stratify tumors into benign and malignant categories. It can be practically used by radiologists to guide patient management, improve multidisciplinary communications, and potentially impact outcomes.

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

Magnetic resonance imaging (MRI) is a common choice among various imaging modalities for the evaluation of hip conditions. Conventional MRI with two-dimensional acquisitions requires a significant amount of time and is limited by partial-volume artifacts and suboptimal fluid-to-cartilage contrast. Recent hardware and software advances have resulted in development of novel isotropic three-dimensional (3D) single-acquisition protocols that cover the volume of the entire hip and can be reconstructed in arbitrary planes for submillimeter assessment of bony and labro-cartilaginous structures in their planes of orientation. This technique facilitates superior identification of small labral tears and other hip lesions with better correlations with arthroscopy. In this review, we discuss technical details related to 3D MRI of the hip, its advantages, and its role in commonly encountered painful conditions that can be evaluated with great precision using this technology. The entities described are femoroacetabular impingement with acetabular labral tears, acetabular dysplasia, avascular necrosis, regional tendinopathies and tendon tears, bursitis, and other conditions.

The purpose of this study was to assess the intra- and inter-reader reliability of the 2 Charcot neuroarthropathy classifications (Sanders-Frykberg and Brodsky-Trepman), as well as Eichenholtz staging. We hypothesized that the inter-reader reliability, with respect to these 3 classification systems, would be moderate at best. Digital radiographic images were organized in a digital slide presentation without clinical information. All 5 reviewers underwent a standard training session administered by the principal investigator, reviewing 5 cases of Charcot neuroarthropathy. Images of 55 cases of Charcot neuroarthropathy and 5 normal cases were distributed to each of the 5 physicians electronically, who independently rated all 60 cases according to the 3 classification systems. The 95% confidence interval of the intraclass correlation coefficient estimate for Sanders-Frykberg was 0.9601 to 0.9833 at week 0 and 0.9579 to 0.9814 at week 8, which can be regarded as "excellent" reliability. For Trepman-Brodsky, the 95% confidence interval of the intraclass correlation coefficient estimate was 0.8463 to 0.9327 at week 0 and 0.8129 to 0.9226 at week 8, which can be regarded as "good" to "excellent" reliability. For Eichenholtz, the 95% confidence interval of the intraclass correlation coefficient estimate was 0.6841 to 0.8640 and 0.6931 to 0.8730 at weeks 0 and 8, respectively, which can be regarded as "moderate" to "good" reliability. The classification systems of Charcot neuroarthropathy are an important tool for communication among physicians. Based on the results at our institution, the Sanders-Frykberg classification exhibited the best inter-reader performance. The Trepman-Brodsky classification exhibited good to excellent reliability as well. The intraclass correlation coefficient of the Eichenholtz classification was moderate to good.

Hallux valgus is a complex deformity with a variety of techniques described for correction. A biplanar plating system for triplanar correction system has been developed to address both the translation and rotational component of the hallux valgus deformity and allow an accelerated weightbearing protocol. The purpose of this study was to determine the correction and complications using radiographic parameters and patient reported outcomes. We sought to determine prognostic factors for successful correction, including age, gender, and preoperative deformity. From the medical records, we collected preoperative data. Patient-reported outcomes were obtained using AOFAS Hallux Metatarsophalangeal-Interphalangeal score, FAAM, and SF-12 scores preoperatively and postoperatively. Imaging was reviewed at preoperative and postoperative visits to determine hallux valgus angle, intermetatarsal angle, and tibial sesamoid position. Fifty-seven procedures, in 55 patients, were performed. There were 7 complications and mean follow-up time was 45.7 weeks (+ 28.3 weeks). Age over 62.5 years were associated with an increased risk of complications (p = .018). Males had an increased rate of complications (71%) compared with females. Radiographic parameters were significantly improved from preoperative values at alltime points (p.05). Only the AOFAS Hallux Metatarsophalangeal-Interphalangeal score was statistically significant at 3, 6 and 12 months. We sought to determine the effectiveness of biplanar plating and triplanar correction procedure with early weightbearing. Over a 12 month follow-up period, our results showed significant improvement in deformity and maintained correction. AOFAS Hallux Metatarsophalangeal-Interphalangeal scores significantly improved from the preoperative to the postoperative state. Our results show a nonunion rate of 5.2%, which is comparable to prior studies.

Bone sclerosis is a focal, multifocal, or diffuse increase in the density of the bone matrix on radiographs or computed tomography (CT) imaging. This radiological finding can be caused by a broad spectrum of diseases, such as congenital and developmental disorders, depositional disorders, and metabolic diseases. The differential diagnosis can be effectively narrowed by an astute radiologist in the light of the clinical picture and typical findings on imaging. Some of these lesions are rare and have been described as case reports and series in the literature. This article aims to collate the clinical-radiologic findings of non-infectious and non-neoplastic causes of bone sclerosis with relevant imaging illustrations.

Shoulder osteoarthritis (OA) is a common and debilitating condition and a source of high morbidity and medical expenditures across the world among individuals older than 60 years. Shoulder OA results in the gradual destruction of articular cartilage of the humeral head and glenoid component, causing inflammation, pain, and a restricted range of motion. Most patients are diagnosed with shoulder OA after experiencing shoulder pain and stiffness, and the diagnosis is often made after medical and physical histories are obtained and physical and imaging examinations are performed. Use of various surgical techniques such as total anatomic or reverse shoulder arthroplasty and hemiarthroplasty has increased in recent years, resulting in reduced morbidity and improved functional status of patients. However, the rate of surgical complications such as premature loosening of components is significant, reducing the effectiveness of such procedures. Data in the literature indicate that high-grade fatty infiltration of the rotator cuff muscle before surgery is associated with postoperative glenoid component loosening. High-grade rotator cuff fatty infiltration and atrophy have been found to be associated with more severe Walch classification-based glenoid morphology subtypes, increased joint line medialization, glenoid bone loss, and increased pathologic glenoid version. The authors describe how advanced imaging techniques are used for preoperative evaluation of the shoulder and discuss how to measure glenoid version and bone stock and classify glenoid morphology types on the basis of Walch classification, as these parameters are commonly used in surgical planning. Methods involving the use of Friedman and paleoglenoid lines for respective measurements are illustrated by using three-dimensional CT and MRI case examples. ©RSNA, 2020.

Objective To evaluate the inter-rater and intermethod correlation (reliability between MRI and arthroscopy) of knee for findings of meniscus tears using International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) classification on both 1.5 and 3.0 T images. Methods 81 knees were evaluated in 69 patients aged 30.0±12.6 years (mean±SD). Consecutive arthroscopy-proven meniscal tears were evaluated by two board-certified radiologists on MRI and two sports surgeons on arthroscopies. The surgically validated ISAKOS classification of meniscal tears was used to describe medial meniscus (MM) and lateral meniscus (LM) tears on MRI and re-evaluation of images from completed arthroscopies. Prevalence-adjusted bias-adjusted kappa (PABAK), t-tests and intraclass correlation coefficient (ICC) were calculated. Results For LM on 1.5 T, the agreements for location, depth, tear length and pattern were good to excellent in all categories except fair for tissue quality (PABAK=0.35–0.41) and zone 2 (PABAK=0.35) identification. For MM, the agreements were good to excellent in all except moderate for tissue quality (PABAK=0.6) and zone 1 and 3 (PABAK=0.40–0.47), and fair for zone 2 identification (PABAK=0.27). Similar results were seen on 3 T with improved LM zonal identification (PABAK=0.52–0.90) and better correlation of tear lengths, which were different on 1.5 T vs 3.0 T (p=0.01–0.03). For 1.5 T cases, both MM and LM tear lengths were larger on MRI versus arthroscopy (MM, p=0.004; LM, p=0.095). For 3 T, the MM tear lengths were larger on MRI versus arthroscopy (p=0.001). Conclusion ISAKOS classification of meniscal tears on both 1.5 and 3.0 T MRI provides satisfactory inter-rater and intermethod reliability for use in clinical practice. Level of evidence: IV.

Purpose Glenoid bone stock and morphology and rotator cuff muscle quality and tendon integrity affect the outcome of total shoulder arthroplasty. We hypothesized that glenoid bone loss correlates with rotator cuff muscle fatty infiltration (FI), tendinopathy, and atrophy. Design Forty-three 3-D CT scans and MRIs of 43 patients (mean age 62 years; SD 13 years; range 22–77 years) referred for primary shoulder pain were evaluated. Measurements of glenoid bone stock, version, and posterior humeral subluxation index (HSI) were assessed on an axial CT image reconstructed in the true scapular plane. Measurements utilized the Friedman line to approximate the pre-pathologic surface. Glenoid morphology was assigned by modified Walch classification. Rotator cuff FI, atrophy, and tendon integrity were assessed on corresponding MRIs. Results There was a very strong negative correlation between increasing glenoid version and HSI (r = − 0.908; p

Introduction: MR neurography (MRN) of the brachial plexus has emerged in recent years as a safe and accurate modality for the identification of brachial plexopathies in pediatric and adult populations. While clinical differentiation of brachial plexopathy from cervical spine-related radiculopathy or nerve injury has long relied upon nonspecific physical exam and electrodiagnostic testing modalities, MRN now permits detailed interrogation of peripheral nerve anatomy and pathology, as well as assessment of surrounding soft tissues and musculature, thereby facilitating accurate diagnosis. The reader will learn about the current state of brachial plexus MRN, including recent advances and future directions, and gain knowledge about the adult and pediatric brachial plexopathies that can be characterized using these techniques.Areas Covered: The review details recent developments in brachial plexus MRN, including increasing availability of 3.0-T MR scanners at both private and academic diagnostic imaging centers, as well as the advent of multiple new vascular and fat signal suppression techniques. A literature search of PubMed and SCOPUS was used as the principal source of information gathered for this review.Expert Opinion: Refinement of fat-suppression, 3D techniques and diffusion MR imaging modalities has improved the accuracy of MRN, rendering it as a useful adjunct to clinical findings during the evaluation of suspected brachial plexus lesions.

Androgen deprivation therapy (ADT) is a cornerstone of advanced prostate cancer (PCa) therapy. Its use is associated with a loss of bone mineral density (BMD) and a greater risk of falls and osteoporotic fractures. In this prospective cohort study, we examined the impact of ADT on muscle and bone strength in men initiating ADT for PCa. Participants were evaluated at three time points: immediately before (week 0), and 6 and 24 weeks after ADT initiation. Study measures included fasting blood levels (for markers of muscle and bone metabolic activity), MRI and QCT imaging (for muscle fat content, and bone density and architecture), and validated clinical tests of muscle strength and gait. Sixteen men completed all study visits. At baseline and throughout the study, participants exercised a median of four times/week, but still experienced weight gain (+2.0 kg at week 24 versus week 0, p = 0.004). Biochemically, all men sustained dramatic early and persistent reductions in sex hormones post‐ADT, along with a progressive and significant increase in serum C‐telopeptide of type I collagen (CTX, +84% at week 24 versus week 0). There was a trend for rise in serum sclerostin (p = 0.09) and interleukin 6 (IL‐6) (p = 0.08), but no significant change in serum myostatin (p = 0.99). Volumetric BMD by QCT declined significantly at the femoral neck (−3.7% at week 24 versus week 0), particularly at the trabecular compartment. On MRI, there were no significant changes in thigh muscle fat fraction. On physical testing, men developed weaker grip strength, but experienced no worsening in lower extremity and lumbar spine muscle strength, or on functional tests of gait. In conclusion, in physically active men, ADT for 24 weeks results in a significant increase in bone resorption and reduction in BMD, but nonsignificant changes in thigh muscle quality (on imaging) or strength and gait (on functional testing). © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

High-resolution ultrasonography (US) and magnetic resonance neurography (MRN) have followed parallel paths for peripheral nerve imaging with little comparison of the two modalities. They seem equally effective to study a variety of neuropathies affecting large and small nerves in the wrist and hand. This article outlines the technical considerations of US and MRN and discusses normal and abnormal imaging appearances of hand and wrist nerves from etiologies such as entrapment, injury, tumor, and proximal and diffuse neuropathy, with specific case illustrations.

Aims Some patients presenting with hip pain and instability and underlying acetabular dysplasia (AD) do not experience resolution of symptoms after surgical management. Hip-spine syndrome is a possible underlying cause. We hypothesized that there is a higher frequency of radiological spine anomalies in patients with AD. We also assessed the relationship between radiological severity of AD and frequency of spine anomalies. Methods In a retrospective analysis of registry data, 122 hips in 122 patients who presented with hip pain and and a final diagnosis of AD were studied. Two observers analyzed hip and spine variables using standard radiographs to assess AD. The frequency of lumbosacral transitional vertebra (LSTV), along with associated Castellvi grade, pars interarticularis defect, and spinal morphological measurements were recorded and correlated with radiological severity of AD. Results Out of 122 patients, 110 (90.2%) were female and 12 (9.8%) were male. We analyzed the radiographs of 122 hips (59 (48.4%) symptomatic left hips, and 63 (51.6%) symptomatic right hips). Average age at time of presentation was 34.2 years (SD 11.2). Frequency of LSTV was high (39% to 43%), compared to historic records from the general population, with Castellvi type 3b being the most common (60% to 63%). Patients with AD have increased L4 and L5 interpedicular distance compared to published values. Frequency of pars interarticularis defect was 4%. Intraclass correlation coefficient for hip and spine variables assessed ranged from good (0.60 to 0.75) to excellent (0.75 to 1.00). Severity of AD did not demonstrate significant correlation with frequency of radiological spine anomalies. Conclusion Patients with AD have increased frequency of spinal anomalies seen on standard hip radiographs. However, there exists no correlation between radiological severity of AD and frequency of spine anomalies. In managing AD patients, clinicians should also assess spinal anomalies that are easily found on standard hip radiographs. Cite this article: Bone Joint J 2021;103-B(8):1351–1357.

The relationship among the severity of the imaging features of femoroacetabular impingement syndrome (FAIS), patient symptoms, and function has not been elucidated. Understanding this relationship helps to improve the prognostic value of imaging. The goal of this study was to examine the correlation of clinical findings, patient pain, and function with severity, as measured with radiographic and 3-dimensional magnetic resonance imaging (3D-MRI). Data collected prospectively through a longitudinally maintained hip database were reviewed, and 37 hips from 31 patients were included. All patients were examined by an experienced orthopedic surgeon, and preoperative radiographs and 3D-MRI were obtained. Preoperatively, the patients completed validated patient-reported outcome measures (PROMs). Mean±SD alpha angles were 69.4°±10.3°, 70.0°±10.3°, 70.6°±8.4°, and 74.8°±9.2° at 12 o'clock, 1 o'clock, 2 o'clock, and 3 o'clock, respectively. Mean lateral center edge angle was 30.1°±5.3°. The authors did not observe a statistically significant correlation between PROMs and the features measured by radiographs and 3D-MRI ( P >.05). In this subset of prospectively imaged patients with FAIS, the authors did not find a correlation between the severity of symptoms measured by PROMs and features on radiographs and 3D-MRI. The severity of dysfunction is multifactorial, and anatomic severity, as measured radiographically and with 3D-MRI, may not correlate with symptoms. Further investigation is necessary to address the sources of patient pain. [ Orthopedics . 2021;44(4):e577–e582.]

Background Chronic groin neuralgia is a life-debilitating condition that plagues patients worldwide. While groin neuralgia is usually traced to iatrogenic causes (inguinal hernia repairs, vasectomy, and hysterectomy), there is a unique subset of patients that present with noniatrogenic groin neuralgia. The diagnosis and treatment of these patients present a particular challenge. Methods A total of 30 patients (current mean age, 46.5 [range: 19–72] years) who presented with noniatrogenic groin neuralgia and received neurectomies on the iliohypogastric, ilioinguinal, and genitofemoral nerves between 2008 and 2017 were identified. A retrospective review of preoperative and immediate postoperative pain scores was compared with prospectively collected current pain on a Likert's scale (0–10). Additionally, patients were asked to complete a Short Form (SF)-20 and identify current pain medications. A two-sided Wilcoxon–Mann–Whitney test was used to analyze the data. Results Of the 30 patients identified, 16 could participate (mean follow-up = 61 months). The average pain reduction for the entire group was 62.7%. When using an established 30% reduction pain as a marker for clinical significance, 12 successful and 4 unsuccessful patients had an average reduction of 81.1 and 7.68%, respectively (success rate of 75%). Patients with successful group showed a statistically significant increased social functioning (p = 0.012) and near-significant increase in mental health (p = 0.063). Improvements, albeit nonsignificant, in mean scaled scores for every other SF-20 quality of life (QoL) category were observed when comparing both groups. Conclusion Neurectomy is a potentially beneficial surgery that can assuage pain and improve quality of life for patients with noniatrogenic groin neuralgia.

Aim: To evaluate the utility of percutaneous CT guided bone biopsy (PCBB) for suspected osteomyelitis (OM) and its eventual impact on patient management and recovery. Material and methods: Patients who received a PCBB for suspected osteomyelitis from years 2012-2018. Patient demographics, lesion location, ulcer grade, signs of toxemia, serology, wound and blood cultures, bone biopsy and cross-sectional imaging results were recorded. Diagnostic yield of the bone biopsy and its role in influencing the final treatment plan and patient recovery were evaluated. Chi-square test was used. P-value less than 0.05 was considered statistically significant. Results: 115 patients with mean age 50.86 ± 14.49 years were included. The common locations were sacrum/ischium (49/115, 43%) and spine (35/115, 30%). Clinically, 40/115 (35%) had toxemia and 67/115 (58%) had ulcers. Per serology, 17/111 (15%), 95/106 (90%), and 86/98 (88%) had an elevated WBC, CRP, and sedimentation rate, respectively. 22/91 (24%) had a positive blood culture and all 23/23 had a positive wound culture. On imaging, definitive and possible OM were reported in 84.1% and 14.2%, respectively, with 1.8% as no OM. Only 24/115 (21%) had a positive bone biopsy culture and only 10/24 (42%) total positive bone cultures impacted the treatment plan. There was no significant effect of antibiotics on the diagnostic yield of culture (p = 0.08). No statistical significance was found when comparing treatment change based on bone culture results versus all other factors combined (p = 0.33), or when comparing clinical improvement with and without positive bone cultures (p = 0.12). Conclusion: Despite positive cross-sectional imaging findings of OM, bone biopsy yield of positive culture is low, and it leads to a small impact in changing the treatment plan or altering the course of patient recovery.

Pediatric musculoskeletal tumors comprise approximately 10% of childhood neoplasms, and MR imaging has been used as the imaging evaluation standard for these tumors. The role of MR imaging in these cases includes identification of tumor origin, tissue characterization, and definition of tumor extent and relationship to adjacent structures as well as therapeutic response in posttreatment surveillance. Technical advances have enabled quantitative evaluation of biochemical changes in tumors. This article reviews recent updates to MR imaging of pediatric musculoskeletal tumors, focusing on advanced MR imaging techniques and providing information on the relevant physics of these techniques, clinical applications, and pitfalls.

Determine correlations of 3DCT cam-type femoroacetabular impingement (FAI) measurements with surgical findings of labral tear and cartilage loss. Digital search of symptomatic cam-type FAI from July 2013 to August 2016 yielded 43 patients. Two readers calculated volumes of femoral head, bump, and alpha angles on 3DCT images. Correlations between CT and surgical findings, inter-, and intra-reader reliabilities were assessed using Spearman rank correlation and intraclass correlation coefficients (ICC). Thirteen men and 14 women aged 37 ± 10 (mean ± SD) years were included. Most common clinical finding was positive flexion–adduction–internal rotation (70.4%). Twenty-seven labral tears and 20 cartilage defects were surgically detected. Significant correlations existed between femoral bump, head volumes, and extent of the labral tear (p = 0.008 and 0.003). No significant correlations were found between the alpha angles at 12 to 3 o’clock and the extent of labral tear (p = 0.2, 0.8, 0.9, and 0.09) or any measurement with the cartilage loss (p values for alpha 12 to 3, bump, and head volumes = 0.7, 0.3, 0.9, 0.9, 0.07, and 0.2). Inter- and intra-reader reliabilities were excellent to moderate for femoral head and bump volumes (ICC = 0.85, 0.52, and 0.8, 0.5) and moderate to poor for alpha angles (ICC = 0.48, 0.40, 0.05, 0.25 and 0.3, 0.24, 0.29, 0.49). Three dimensional volumetric measurements of cam-type FAI significantly correlate with the extent of intraoperative labral tears. Superior inter- and intra-reader reliability to that of alpha angles renders it a more clinically relevant measurement for quantifying cam morphology. • The 3DCT bump volume and femoral head volume showed significant correlations with the extent of labral tear (p values = 0.008 and 0.003). • No significant correlations were seen between alpha angles and the extent of labral tear (p values > 0.05). • Inter- and intra-reader reliability was excellent to moderate (ICC = 0.85 and 0.52, 0.8, and 0.5) for femoral head and bump volumes while inter- and intra-reader reliability was fair to poor (ICC = 0.48, 0.40, 0.05, 0.25 and 0.3, 0.24, 0.29, 0.49) for alpha angles.

Sickle cell anemia is an inherited disorder with many systemic complications. Peripheral neuropathy related to this disorder has been sparsely reported. We report an interesting case of upper limb peripheral neuropathy from sickle cell disease with emphasis on MR neurography appearances and electrophysiology correlation.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of spindled to epithelioid cells that co-express both melanocytic and myogenic markers. Recently, in 2018, a distinctive variant of PEComa has been described that arises in association with tuberous sclerosis complex (TSC) and resembles a fibroma by conventional morphology (called fibroma-like PEComa). Herein, we describe a case of a fibroma-like PEComa in a 4-year-old male child with a known diagnosis of tuberous sclerosis who presented with a firm mass along the anteromedial aspect of the right knee. The mass was excised, and microscopic examination showed bland spindled to stellate cells embedded in a dense collagenous stroma, morphologically resembling a fibroma. Immunohistochemistry analysis showed positivity for desmin (a myogenic marker) and HMB45 (a melanocytic marker), a hallmark for PEComas. To our knowledge, only six cases of fibroma-like PEComa have been described in the literature so far and this is the first report of such a tumor in the medial retinaculum of the knee joint with illustrations of conventional and diffusion imaging features. This case highlights the unique association of fibroma-like PEComa lesions with TSC. This should be considered a differential diagnosis for T2 hypointense masses in tuberous sclerosis patients. In addition, a diagnosis of fibroma-like PEComa should prompt further evaluation for associated TSC.

Bone tumors and tumor-like lesions (pseudotumors) are not uncommonly encountered as asymptomatic findings on imaging, or as symptomatic lesions clinically. Radiographic imaging is the first diagnostic tool for their management strategy, since the symptoms are commonly non-specific, such as pain, swelling, and redness. Image findings must be analyzed with attention to the specific features such as lesion location, margination, zone of transition, mineralization, size and multifocality, soft tissue component and/or loco-regional extent. Cross-sectional imaging including CT and MRI serve as complementary methods, providing additional information with respect to the lesion characterization, mineralization, extent and involvement of the adjoining soft tissues. Clinical and/or key imaging features aid in limiting the differential diagnostic possibilities and serve as a guide in determining the benignity or malignancy of the tumor as well as to exclude pseudotumors. This article reviews the key imaging features of foot and ankle lesions. Benign bone lesions include simple and aneurysmal bone cysts, lipoma, hemangioma, chondroblastoma, enchondroma, osteoid osteoma, osteoblastoma, and giant cell tumor. Locally aggressive intermediate category lesion includes hemangioendothelioma. Malignant lesions include osteosarcoma, Ewing's sarcoma, chondrosarcoma. Pseudotumors such as fibrous dysplasia, hemophilic pseudotumor, gout and Madura foot are also discussed with illustrative case examples.

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: The majority of hallux valgus corrections are performed via a uniplanar metatarsal osteotomy approach in which the metatarsal is cut and shifted over in the transverse plane. This approach has demonstrated high long-term recurrence rates. Recent research demonstrates that 87% of hallux valgus deformities are three-dimensional with abnormal frontal-plane rotation of the metatarsal, which cannot be fully addressed with a uniplanar metatarsal osteotomy. While correction at the 1st tarsometatarsal (TMT) joint may provide the optimal surgical approach for 3D anatomic restoration at the apex of the deformity, 1st TMT fusion has historically involved an extended period of non-weightbearing. This study evaluates the clinical, radiographic, and patient-reported outcomes in patients undergoing instrumented triplanar 1st TMT arthrodesis (TTA) with a biplanar plating system and protected near-immediate weightbearing. Methods: This is a prospective multicenter study that will continue for 60 months post-operatively. Patients between 14-58 years old with symptomatic hallux valgus (intermetatarsal and hallux valgus angles between 10.0-22.0° and 16.0-40.0°, respectively) and no prior hallux valgus surgery on the operative foot are eligible for this study. Patients are treated with an TTA procedure using a biplanar plating system with protected near-immediate weightbearing. Outcomes (radiographic, range of motion (ROM), pain measured by visual analog scale (VAS), Manchester-Oxford Foot Questionnaire (MOxFQ), return to weightbearing and activities) are evaluated post-operatively. Two independent musculoskeletal radiologists reviewed radiographic data. These interim results are limited to patients completing at least 6 weeks of follow-up. Results: At time of data cut-off, 74 patients had undergone TTA with at least 6 weeks follow-up. The majority of patients were women (95%) with mean age 41.7 years. The mean (95% confidence interval) time to protected weightbearing in CAM boot was 8.0 (6.4, 9.7) days, return to work was 19.0 (13.6, 24.4) days, and return to full work was 31.5 (22.7, 40.2) days. There was a significant change in radiographic measures pre vs. post procedure and changes were maintained over time (Table). VAS pain score decreased 4 and 6 months post-procedure by 3.9 (3.2, 4.6) and 4.2 (3.5, 5.0), respectively. The mean MOxFQ Index Score pre-procedure was 53.3 (49.5, 57.1) and at month 6 had decreased to 18.6 (12.9, 24.2). Conclusion: These interim findings support that TTA with biplanar plating is successful in correcting the 3D hallux valgus deformity with early return to weightbearing and demonstrated favorable clinical and patient-reported outcomes. Patients were able to return to full, unrestricted work and activities within just a few months and had meaningful pain reduction after surgery. Patients will continue to be followed for up to 60 months. Clinical/radiographic healing at 12 months and recurrence rates at 24 months, as well as complications and patient satisfaction, will be evaluated. [Table: see text]

To analyze the trends in international medical graduates (IMGs) matching into diagnostic radiology residency programs in the United States (US).The National Resident Match Program data was accessed for years 2005-2020 and diagnostic radiology residency-specific data was extracted for US MD, osteopathic (DO), and IMG applicants. IMGs were categorized into US-citizen IMGs and non-US citizen IMGs per the National Residency Match Program. Variables collected for each year included the number of positions, number of applicants in each group, positions filled/unfilled, and fill rate of each group. Additional data for some years included USMLE Step 1 score, United States Medical Licensing Examination (USMLE) Step 2 clinical knowledge (CK) score, number of research experiences, number of abstracts/publications, and additional degrees obtained. Trends were analyzed using simple linear regression model and p value0.05 was considered significant.The number of diagnostic radiology residency programs increased from 203 (2006) to 212 (2020). The total number of diagnostic radiology residency positions increased from 1011 (2006) to 1113 (2020), with the peak of 1145 in 2014. The overall "match rate," that is, proportion of positions filled to positions available, increased from 96.4% (2006) to 97.3% (2020), with a brief decline to 86.7% in 2015. Among the filled positions, the proportion filled by US medical school graduates significantly declined from 89.7% (2006) to 69.2% (2020) (p0.001), and the proportion of positions filled by osteopathic seniors and graduates significantly increased from 2.2% (2006) to 15.1% (2020; p0.001). The proportion of US IMGs increased from 3.2% (2006) to 5.4% (2020), while the proportion of non-US IMGs increased from 4.4% (2006) to 9.4% (2020), with overall IMG match rate increased significantly from 7.6% to 14.9% (p = 0.009). The mean Step 1 scores of US IMGs and non-US IMGs were 238 and 237.3, and the mean Step 2 CK scores were 241.67 and 241, respectively. Cumulatively over the study period, a total of 736 US IMGs and 1051 non-US IMGs have matched into diagnostic radiology residency.There is an increasing proportion of IMGs, especially the non-US citizen IMGs, matching into US radiology residency programs in the last decade. Diagnostic radiology remains a competitive specialty evidenced by average USMLE scores higher than national average and research experiences of matched candidates.

The role of MRI in the preoperative diagnosis of knee cartilage injury and postoperative follow-up as it relates to the visualization, assessment, and characterization of cartilage repair tissue is described in this chapter. Whereas the cartilage repair tissue-specific MR techniques and the morphological/biochemical outcome of a given cartilage repair treatment procedure are reviewed, this chapter summarizes the routinely used techniques and their advantages. It also provides an overview of the available treatment options, including their indications, technique, and clinical results, and illustrates the MR morphology of repair sites as well as postoperative complications. Further, the magnetic resonance observation of cartilage repair tissue (2D and 3D MOCART) scoring system, which has been well validated in studies of cartilage regeneration techniques, is discussed.

Peripheral nerve sheath tumors (PNSTs) account for ~ 5% of soft tissue neoplasms and are responsible for a wide spectrum of morbidities ranging from localized neuropathy to fulminant metastatic spread and death. MR imaging represents the gold standard for identification of these neoplasms, however, current anatomic MR imaging markers do not reliably detect or differentiate benign and malignant lesions, and therefore, biopsy or excision is required for definitive diagnosis. Diffusion-weighted MR imaging (DWI) serves as a useful tool in the evaluation and management of PNSTs by providing functional information regarding the degree of diffusion, while diffusion tensor imaging (DTI) aids in determining the directional information of predominant diffusion and has been shown to be particularly useful for pre-operative planning of these tumors by delineating healthy and pathologic fascicles. The article focuses on these important neurogenic lesions, highlighting the current utility of diffusion MR imaging and future directions including computerized radiomic analysis. KEY POINTS: • Anatomic MRI is moderately accurate in differentiating benign from malignant PNST. • Diffusion tensor imaging facilitates pre-operative planning of PNSTs by depicting neuropathy and tractography. • Radiomics will likely augment current observer-based diagnostic criteria for PNSTs.

Nonobstetric traumatic brachial plexus injuries can result in significant morbidity and chronic disability if not managed in a timely manner. Functional arm recovery is possible, but it requires a multidisciplinary approach toward the diagnosis and management of such injuries.This article provides an overview of the clinical, electrophysiology, and diagnostic imaging knowledge needed for accurate imaging interpretation and to participate in multidisciplinary discussions aimed at expediting optimal patient management.

Distal radioulnar joint (DRUJ) dysfunction is a common cause of ulnar sided wrist pain. Physical examination yields only subtle clues towards the underlying etiology. Thus, imaging is commonly obtained towards an improved characterization of DRUJ pathology, especially multimodality imaging, which is frequently resorted to arrive at an accurate diagnosis. With increasing use of advanced MRI and CT techniques, DRUJ imaging has become an important part of a musculoskeletal radiologist's practice. This article discusses the normal anatomy and biomechanics of the DRUJ, illustrates common clinical abnormalities, and provides a comprehensive overview of the imaging evaluation with an insight into the role of advanced cross-sectional modalities in this domain.

To analyze the impact of pelvic computed tomography (CT) technique optimization on estimated dose and subjective and objective image quality. An institutional review board (IRB)-approved retrospective records review was performed with waived informed consent. Five CT scanners (various manufacturers/models) were standardized to match the lowest dose profile on campus via subjective assessment of clinical images by experienced musculoskeletal radiologists. The lowest dose profile had previously been established through image assessment by experienced musculoskeletal radiologists after a department-wide radiation dose reduction initiative. A consecutive series of 60 pre- and 59 post-optimization bony pelvis CTs were analyzed by two residents, who obtained signal-to-noise ratio for femoral cortex and marrow, gluteus medius muscle, and subcutaneous and visceral fat in a standardized fashion. Two blinded attending radiologists ranked image quality from poor to excellent. Pre- and post-optimization subjects exhibited no difference in gender, age, or BMI (p > 0.2). Mean CT dose index (CTDIvol) and dose–length product (DLP) decreased by approximately 45%, from 39± 14 to 18± 12 mGy (p

Retrospective clinical case series.To study the role of magnetic resonance neurography (MRN) of the lumbosacral plexus in management of patients with failed back surgery syndrome (FBSS).FBSS is one of the major problems in health care, affecting up to 40% of patients after spine surgery. To date, no imaging modality has been used to effectively classify nerve compression, because nerve injuries are challenging to detect on conventional lumbar spine magnetic resonance imaging (MRI). To our knowledge, no previous studies have addressed the use of MRN in FBSS or compared it to lumbar spine MRI.From 203 consecutive 3 T MRN studies of lumbosacral plexus in 1 year, 12% (25/203) presented as FBSS. Demographic data, number of previous lumbar MRIs and their findings, MRN findings, interval between MRI and MRN, pre-and post-MRN diagnosis, pain levels, and treatments were recorded. Changes in diagnosis, treatment, and outcomes after MRN were determined.The final sample of 25 patients had a mean age 62 ± 15 and male to female ratio 1:1.08. Approximately 88% (22/25) had previous lumbar MRI, of which 27% had 3 or more. Most common imaging findings were neuroforaminal stenosis 22.6% (7/31) on MRI and neuropathy 22.9% (19/83) on MRN. Mean interval between MRI and MRN was 13.9 ± 28.3 months. Lumbar MRIs were inconclusive in 36% (8/22). MRN detected 63% (52/83) more findings and changed the diagnosis and treatment in 12% and 48% of FBSS cases, respectively. Favorable outcomes were recorded in 40% to 67% of patients following MRN-guided treatments.FBSS is a complex problem and MRN of lumbosacral plexus impacts its management by better directing source of symptoms.4.

Background/Objective Low back and pelvic pain are among the most prevalent conditions worldwide, with major social and economic costs. The aim of this study was to evaluate the role of magnetic resonance neurography (MRN) of lumbosacral plexus in the management and outcomes of these patients with chronic pain. Methods Consecutive patients with chronic lumbosacral and pelvic pain referred for MRN over a year were included. Preimaging and postimaging clinical diagnosis and treatment, pain levels, and location were recorded. Pain-free survival was compared between treatments using a Cox proportional hazards model. Results A total of 202 patients with mean age 53.7 ± 14.8 years and a male/female ratio of 1:1.53 were included. Of these patients, 115 presented with radiculopathy (57%), 56 with pelvic pain (28%), and 31 with groin pain (15%). Mean initial pain level was 6.9 ± 1.9. Mean symptom duration was 4.21 ± 5.86 years. Of these patients, 143 (71%) had a change in management because of MRN. After MRN, reduction in pain levels was observed in 21 of 32 patients receiving conservative treatment (66%), 42 of 67 receiving injections (63%), and 27 of 33 receiving surgery (82%). Follow-ups were available in 131 patients. Median pain-free survival was 12 months. Patients treated with surgery had significantly lower pain recurrence than patients receiving other treatments in the same time frame (hazard ratio, 3.6; 95% confidence interval, 1.4–9.2; P = 0.0061). Conclusions MRN use in chronic lumbosacral and pelvic pain led to a meaningful change in diagnosis and treatment. After MRN, conservative treatment and injections provided pain relief; however, patients benefited more from surgery than from any other treatment.

High-resolution ultrasound serves as a fast, accessible, reliable, and radiation-free tool for anatomical and dynamic evaluation of various peripheral nerves. It can be used not only to identify and diagnose peripheral nerve and perineural pathology accurately but also to guide various nerve and perineural interventions. We describe the normal and pathologic appearances of peripheral nerves, the pathologies commonly affecting the individual peripheral nerves, and the current ultrasound-guided peripheral nerve interventions and techniques. Future directions are also highlighted.

Magnetic resonance neurography is a technique for identifying anatomy and pathologic lesions of nerves, and has emerged as a helpful technique for localizing lesions and elucidating the underlying etiology. Ganglioneuromas are highly differentiated benign tumors. This lesion is rare and exhibits undetermined symptoms, the features of using the magnetic resonance neurography are a great ally to determine its diagnosis. The authors illustrate a case of retroperitoneal ganglioneuroma emphasizing its image characteristics using magnetic resonance neurography with the diagnosis confirmed by histopathological examination. Keywords: Ganglioneuroma, Lumbosacral plexus, MRI, MRN

Background Increased visceral adipose tissue (VAT) is associated with systemic inflammation through amplified production of pro-inflammatory cytokines like TNF-α and interleukin-6. Higher visceral fat index (VFI), which is the ratio of VAT to subcutaneous adipose tissue (SAT) and reflects the degree of excess VAT in relation to SAT, is associated with complex IBD. However, its relevance to treatment response is unclear. We aim to evaluate the effect of VFI on treatment response and risk of surgery in IBD patients starting anti-TNF therapy. Methods IBD patients starting anti-TNF agents between 1/1/2009 to 7/31/2019 at two academic medical centers were included. Three dimensional VAT and SAT volumes were measured from CT scans with Aquarius (iNtuition, Foster City, CA). VFI was calculated with the ratio of VAT:SAT. Patients were categorized by predefined VFI cutoffs: 0.67. Primary outcomes included composite endpoint of corticosteroid-free response (CFR) at 6 and 12 months defined by meeting one of the following: a) clinical response based on Harvey Bradshaw Index for Crohn’s disease (CD) or Lichtiger score for ulcerative colitis (UC), b) endoscopic improvement based on ulcer healing for CD and Mayo score for UC compared to baseline, or c) 50% improvement or normalization of CRP or fecal calprotectin. Secondary outcomes included IBD-related surgery at 6 and 12 months. We performed a multivariable logistic regression on CFR and surgery, adjusting for age, gender, IBD diagnosis, disease duration, active tobacco use, and immunomodulator exposure, to calculate adjusted odds ratio (aOR) and 95% confidence interval (CI). Results We included 181 patients. Table 1 summarizes differences in baseline characteristics. There were no differences in disease severity or activity. There were no differences in CFR at 6 and 12 months (Figure 1a and b). With respect to surgery within 6 months, patients with VFI >0.67 were significantly more likely to undergo surgery (aOR: 41.92 [95%CI 5.09–345.59]), but no difference in patients with VFI 0.33–0.66 was observed when compared to patients with VFI 0.67 were more likely to undergo surgery (aOR: 15.55 [95%CI 2.85–80.56]) but no difference was observed in patients with VFI 0.33–0.66 compared to patients with VFI Conclusion In this retrospective, multicenter, cohort study, we found higher VFI is associated with increased odds of surgery in IBD patients starting anti-TNF therapy. If confirmed by future prospective studies, VFI may be employed as a biomarker to help identify IBD patients at risk for medically refractory disease and would benefit from an early surgical referral, especially considering the growing application of artificial intelligence in medical imaging.

To assesses whether utilising bone marrow oedema (BMO) maps improved fracture read times and reader confidence in a large series of acute lower extremity trauma dual-energy computed tomography (DECT) studies.One hundred and six DECT studies, including 60 fracture cases and 46 non-fracture cases, were evaluated retrospectively in this cross-sectional study. Three-dimensional (3D) BMO maps were generated for each study and coded to display skeletal anatomy in blue and marrow oedema in green. Studies were interpreted by two readers in two timed stages (without and with BMO maps). Readers identified the number, anatomical location, and comminution of fractures. Reader confidence (five-point Likert scale) for fracture identification and anatomical regions where oedema was present was also recorded.Decreased read times (p0.01) were observed when readers utilised BMO maps for their fracture search. The presence of oedema on BMO maps corresponded with associated fracture in 75.7% reads. No differences in reader confidence were observed as a result of using this BMO-guided technique (95%, 5/5 for both readers with and without the aid of BMO maps).DECT BMO maps improve the speed of radiological identification of suspected acute lower extremity fractures with preserved reader confidence. It may help emergent detection of fractures, important for patient management and outcomes.

The shoulder is the most frequently dislocated joint in the body due to a larger range of motion and a small area of articulation between the humeral and glenoid surfaces. Traumatic shoulder dislocations, especially those associated with injury to the labroligamentous or bony stabilizers of the joint, lead to further reduction of articular surface contact with resultant glenohumeral instability and recurrent shoulder dislocations. Imaging plays an increasingly important role in the preoperative evaluation of patients with traumatic shoulder instability by evaluating glenohumeral bone loss (uni- or bipolar), assessing soft tissue injuries and identifying patients at risk of postoperative recurrence. Quantification of bone loss is key to differentiate engaging vs. non-engaging Hill–Sachs lesions, while newer concepts of “on-track” vs. “off-track” lesions are being discussed that can determine the required surgical approaches. In this article, we review the preoperative imaging approaches, traditional treatments, outline the bone loss measurement strategies and review these new tracking concepts with relevant case examples.

Background Majority of musculoskeletal cross-sectional imaging requests have a non-revealing and non-specific clinical history of pain. However, the location of pain is very relevant towards arriving at a specific orthopedic diagnosis. The purpose of this research was to study the impact of skin marker placement and training of technologists prior to knee MRI in detection of clinically important findings. Methods Total 200 consecutive left knee MRIs were evaluated before and after technologist training with regards to marker placement at the site of clinical symptoms or palpable finding. Marker location in relation to the knee was recorded and important findings were classified as correlated important finding, non-correlated important finding, other compartment important finding in non-correlated cases, and diffuse abnormality, i.e. tri-compartmental cartilage defects in both correlated and non-correlated cases. Differences among scans before and after technologist training were analyzed. Results The marker placement was observed in higher proportion of patients in post-training scans (78% vs 60%, p = 0.00). The most common location of the marker was in anterior or anterolateral knee (32% and 34% cases, respectively). The marker-important finding correlation was also higher post training, but not statistically significant (53% versus 38%, p = 0.57). Important findings correlated with the marker in more than 50% of the scans in the post-training set. Conclusion Marker placement can aid in detection of clinically important imaging finding and technologist training aids in increased rates of marker placement and improved correlation.

Chronic pelvic pain can result from various intra- and extra-pelvic etiologies. Although patient history and physical examination may narrow the differential diagnosis, frequently, the different etiologies have overlapping presentations. Imaging examinations such as US and/or MR imaging may help delineate the cause of pain, particularly when related to intra-pelvic organs, pelvic floor dysfunction or prolapse, synthetic material such as pelvic mesh or slings, and in some cases of neuropathic pain. Etiologies of neuropathic pain can also be assessed with non-imaging tests such as nerve conduction studies, electromyography, and testing of sacral reflexes.

Superior capsular reconstruction (SCR) is a novel technique for treating irreparable rotator cuff tears in younger patients in whom a reverse total shoulder arthroplasty is not the optimal treatment choice. This case study describes a middle-aged male with a recurrent, massive, irreparable rotator cuff tear treated with SCR that subsequently failed at the glenoid attachment. The patient underwent successful arthroscopic revision of the SCR. The case illustrates the MRI and arthroscopic correlations of the failed dermal allograft reconstruction, which to our knowledge has not been previously shown in the radiology literature.

Magnetic resonance neurography (also called MRN or MR neurography) refers to MR imaging dedicated to the peripheral nerves. It is a technique that enhances selective multiplanar visualisation of the peripheral nerve and pathology by encompassing a combination of two-dimensional, three-dimensional and diffusion imaging pulse sequences. Referring physicians who seek imaging techniques that can depict and diagnose peripheral nerve pathologies superior to conventional MR imaging are driving the demand for MRN. This article reviews the pathophysiology of peripheral nerves in common practice scenarios, technical considerations of MRN, current indications of MRN, normal and abnormal neuromuscular appearances, and imaging pitfalls. Finally, the emerging utility of diffusion-weighted and diffusion tensor imaging is discussed and future directions are highlighted. • Lesion relationship to neural architecture is more conspicuous on MRN than MRI. • 3D multiplanar imaging technique is essential for pre-surgical planning. • Nerve injuries can be classified on MRN using Sunderland’s classification. • DTI provides quantitative information and insight into intraneural integrity and pathophysiology.