Mentorship in academic musculoskeletal radiology: perspectives from a junior faculty member.

The first years of an academic musculoskeletal (MSK) faculty position are a time of transition for the junior faculty member, who must rapidly adjust to new clinical, academic, operational, and professional responsibilities. Mentoring has a critical role in helping the faculty member to thrive in these early years. Establishing clear communication, trust, and expectations can set the foundation for an effective mentoring relationship. Junior faculty members ideally would have multiple mentors with different areas of expertise, including mentors of all roles in MSK radiology but also in other radiology divisions and other departments. Private practice MSK radiologists can also benefit from mentorship. Barriers to mentoring in MSK radiology include overall smaller division sizes, a newer and smaller field on a national level, and the increase in clinical volume and remote work that results in less face-to-face interaction. Despite the challenges, both junior MSK faculty members and their mentors can benefit greatly from strong mentoring connections.

Ultrasound appearance of regenerative peripheral nerve interface with clinical correlation.

OBJECTIVE: To describe the ultrasound (US) appearance of regenerative peripheral nerve interfaces (RPNIs) in humans, and correlate clinically and with histologic findings from rat RPNI. MATERIALS AND METHODS: Patients (≥ 18 years) who had undergone RPNI surgery within our institution between the dates of 3/2018 and 9/2019 were reviewed. A total of 21 patients (15 male, 6 female, age 21-82 years) with technically adequate US studies of RPNIs were reviewed. Clinical notes were reviewed for the presence of persistent pain after RPNI surgery. Histologic specimens of RPNIs in a rat model from prior studies were compared with the US findings noted in this study. RESULTS: There was a variable appearance to the RPNIs including focal changes involving the distal nerve, nerve-muscle graft junction, and area of the distal sutures. The muscle grafts varied in thickness with accompanying variable echogenic changes. No interval change was noted on follow-up US studies. Diffuse hypoechoic swelling with loss of the fascicular structure of the nerve within the RPNI and focal hypoechoic changes at the nerve-muscle graft junction were associated with clinical outcomes. US findings corresponded to histologic findings in the rat RPNI. CONCLUSION: Ultrasound imaging can demonstrate various morphologic changes involving the nerve, muscle, and interface between these two biological components of RPNIs. These changes correspond to expected degenerative and regenerative processes following nerve resection and muscle reinnervation and should not be misconstrued as pathologic in all cases. N5 and N1 morphologic type changes of the RPNI were found to be associated with symptoms.

Ultrasound of myxofibrosarcoma.

The ultrasound appearance of myxofibrosarcoma is highly variable corresponding to its variable and at times heterogeneous histopathologic appearance. Myxofibrosarcomas may mimic a benign process and the infiltrative tumor margins may be difficult to precisely delineate on ultrasound imaging. These tumor characteristics pose a diagnostic challenge on ultrasound evaluation. The radiologist should be aware of the variable morphologic presentation and infiltrative nature of myxofibrosarcoma and the limitations of ultrasound in the initial diagnosis, biopsy guidance, and post-surgical follow-up of this tumor.

Imaging the intermuscular septum in the context of ulnar neuropathy.

Impingement/entrapment of the ulnar nerve by the intermuscular septum at the distal arm is a common cause of recurrent or recalcitrant ulnar neuropathy following ulnar nerve decompression or anterior transposition. Primary entrapment/impingement of the ulnar nerve along the intermuscular septum may also occur. Evaluation with both ultrasound (US) and MRI can identify entrapment of the ulnar nerve at the intermuscular septum, while dynamic assessment with US can also identify dynamic subluxation of the ulnar nerve over the intermuscular septum.

Imaging appearance of well-differentiated liposarcomas with myxoid stroma.

OBJECTIVE: Describe the imaging appearance of well-differentiated liposarcoma with myxoid stroma (WDLMS) and correlate with histopathology. MATERIALS AND METHODS: A keyword search of the institution medical records was performed from 1 January 2000 to 30 June 2017. The histopathology slides of cases identified in this fashion were then reviewed by a pathologist. Additional cases were prospectively collected from extramural referrals and tumor boards. Diagnostic imaging studies of pathologically proven cases of WDLMS were then reviewed in consensus and correlated with pathology. RESULTS: Ten cases of pathologically proven WDLMS were identified (7 men, 3 women, ages 26-81). Tumor location included the retroperitoneum (n = 5), thigh (n = 4), and the shin (n = 1). Nine patients had macroscopic fat on imaging. The nonlipomatous components had a variable appearance, including septal, nodular, and lacelike patterns. Two cases included two distinct areas that were predominantly myxoid or lipomatous ("bi-morphic"). One tumor had no macroscopic fat on imaging. On CT, the nonlipomatous nodular components were hypodense/had hypodense areas. On MRI, the nodular components had intermediate/bright T2W signal. Interval nonlipomatous nodular growth was identified in 3 cases. CONCLUSION: WDLMS may present on imaging as a mass with variable morphology and amounts of nonlipomatous components. Histopathological diagnosis of WDLMS is challenging and imaging correlation may be helpful, as this tumor may have ≥50% fatty volume, may have a myxoid nodular component or bi-morphic appearance, or may be located in the retroperitoneum, features that are unusual for myxoid liposarcoma. WDLMS with a nodular component cannot be distinguished from dedifferentiated liposarcoma based on imaging alone.

Creating Three-dimensional Printed Models of Acetabular Fractures for Use as Educational Tools.

Acetabular fractures are frequently encountered in some clinical practices, and the precise classification of these fractures greatly influences treatments and outcomes. The authors identified the need for an educational aid when teaching acetabular fracture classifications, given the complex spatial anatomy and the nonintuitive classification system that is commonly used. Three-dimensional ( 3D three-dimensional ) printing is an evolving technique that has applications as an educational aid, providing the student with a tangible object to interact with and learn from. In this article, the authors review their experience creating 3D three-dimensional printed models of the hip for educational purposes. Their goal was to create 3D three-dimensional printed models for use as educational aids when teaching acetabular fracture classifications. Complex cases involving a combination of fracture types, subtle nondisplaced fractures, and/or fractures with associated osteopenia or artifacts were excluded. The selected computed tomographic (CT) scans were loaded into a medical 3D three-dimensional volume-rendering program, and a 3D three-dimensional volumetric model was created. Standard Tessellation Language ( STL Standard Tessellation Language ) files were then exported to STL Standard Tessellation Language model-editing software and edited to retain only the involved hemipelvis. In some cases, the proximal femur and ipsilateral hemisacrum may be included to emphasize hip alignment or disruption of the force transfer. Displaced fracture fragments can be printed as separate segments or a single unit after the addition of struts. Printing was performed by using an additive manufacturing principle, with approximately 36-48 hours needed for printing, postprocessing, and drying. The cost to print a 1:1 scale model was approximately $100-$200, depending on the amount of plastic material used. These models can then be painted according to the two-column theory regarding acetabular fractures. ©RSNA, 2017.

Imaging Nerve Pathology of the Knee: Magnetic Resonance Imaging and Ultrasound.

Peripheral neuropathies are not uncommon, and the diagnostic evaluation includes a clinical assessment and electrophysiologic studies as well as diagnostic imaging. Magnetic resonance imaging (MRI) and high-resolution ultrasound (HRUS) are of special importance in providing the surgeon with information in the context of nerve trauma, entrapment, and nerve involvement by tumors. Peripheral neuropathy about the knee can occur in the context of associated knee pathology such as trauma, as part of a systemic disease, or as an isolated finding. In this review, we discuss the role of MRI and HRUS in the evaluation of peripheral neuropathy and present imaging examples of peripheral neuropathy involving the knee.

Ultrasound evaluation of bursae: anatomy and pathological appearances.

A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.

US of the Peripheral Nerves of the Upper Extremity: A Landmark Approach.

Ultrasonography (US) has become a first-line modality for the evaluation of the peripheral nerves of the upper extremity. The benefits of US over magnetic resonance (MR) imaging include higher soft-tissue resolution, cost effectiveness, portability, real-time and dynamic imaging, and the ability to scan an entire extremity quickly and efficiently. US can be performed on patients who are not eligible for MR imaging. Metallic implant artifacts are usually not problematic. US has been shown to have equal specificity and greater sensitivity than MR imaging in the evaluation of peripheral nerves. Any abnormal findings can be easily compared with the contralateral side. The published literature has shown that US has demonstrated clinical utility in patients with suspected peripheral nerve disease by guiding diagnostic and therapeutic decisions as well as by confirming electrodiagnostic findings. Common indications for upper extremity peripheral nerve US are the evaluation for injury due to penetrating trauma, entrapment by scar tissue, and tumor. US of the upper extremity is most commonly performed to evaluate carpal and cubital tunnel syndrome. It is important for the radiologist or sonographer to have a detailed knowledge of anatomy and specific anatomic landmarks for each nerve to efficiently and accurately perform an examination. The goal of this article is to introduce readers to the basics of US of the peripheral nerves of the upper extremity with a focus on the median, ulnar, and radial nerves. Common sites of disease and the location of important anatomic landmarks will be reviewed.

US of the Peripheral Nerves of the Lower Extremity: A Landmark Approach.

Ultrasonography (US) is commonly used to assess the peripheral nerves of the lower extremity because of its many advantages over magnetic resonance (MR) imaging. The most obvious advantages over MR imaging are superior soft-tissue resolution, low cost, portability, lack of magnetic susceptibility artifact, and the ability to image patients who cannot undergo MR imaging. US has been shown to have equal specificity and greater sensitivity than MR imaging in the evaluation of peripheral nerves. Additional benefits are the capability of real-time and dynamic imaging, and the ability to scan an entire extremity quickly without the need for a patient to lie motionless for long periods of time, as with MR imaging. Any abnormal findings can be easily compared against the contralateral side. Published literature has shown that US has clinical utility in patients suspected of having peripheral nerve disease: US can be used to guide diagnostic and therapeutic decisions, as well as help confirm electrodiagnostic findings. Common indications for lower extremity peripheral nerve US are the evaluation for injury due to penetrating trauma, entrapment by scar tissue, or tumor. To confidently perform US of the peripheral nerves of the lower extremity, it is important to gain a thorough knowledge of anatomic landmarks and the course of each nerve. Readers who may not be familiar with US will be introduced to the basics of scanning the peripheral nerves of the lower extremity. Important anatomic landmarks and common sites of injury and entrapment will be reviewed.

Myxoinflammatory fibroblastic sarcoma: spectrum of disease and imaging presentation.

OBJECTIVES: To describe the imaging findings of a series of myxoinflammatory fibroblastic sarcomas (MFSs) from our institution, including a case of dedifferentiated MFS and two cases with areas of high-grade tumor, in addition to typical cases of low-grade tumor. To correlate the imaging findings with the pathologic features of these tumors. SUBJECTS AND METHODS: IRB approval was obtained. Retrospective search of the pathology database at our institution from 2000 to 2015 identified seven cases of MFS with available imaging. Imaging, pathology, and clinical data were reviewed. RESULTS: Unlike the majority of well-differentiated tumors in our series (four cases), one tumor showed dedifferentiation and two cases had areas of high-grade tumor. The dedifferentiated tumor showed peripheral post-contrast enhancement. One case with a substantial high-grade component showed osseous destruction and peripheral enhancement in the high-grade area, while the low-grade component enhanced diffusely. The second case had a small high-grade area and showed diffuse enhancement. All three of these cases had non-acral locations and lacked association with a tendon. The four cases of low-grade MFS demonstrated diffuse enhancement, were located in the distal extremities, and were associated with a tendon. CONCLUSION: The imaging findings of dedifferentiated and high-grade MFS differ from the more typical low-grade tumors in that they have nonenhancing areas, a non-acral location, lack association with a tendon, and may involve bone. The radiologist should be aware that MFS represents a spectrum that includes low-grade tumors, tumors with high-grade areas, and tumors with dedifferentiation and that this spectrum presents with differing imaging features.

Knee MRI: Vascular Pathology.

OBJECTIVE: Patients who undergo knee MRI for presumed musculoskeletal disease can have unexpected vascular findings or pathology in the imaged field. Some vascular processes are limb threatening and affect treatment planning and patient outcome. CONCLUSION: Unexpected vascular findings on knee MRI can range from incidental to symptomatic and can include such processes as variant anatomy, aneurysm, traumatic injury, and neoplasm. The assessment for vascular pathology should be a key component of every radiologist's search pattern when evaluating knee MRI.

Prevalence of the acetabular sublabral sulcus at MR arthrography in patients under 17 years of age: does it exist?

PURPOSE: To retrospectively determine characteristics of contrast-filled acetabular labral clefts in patients under the age of 17 years at MR arthrography (Mra) correlated with arthroscopy, which may impact the thinking regarding the existence of a sublabral sulcus. MATERIALS AND METHODS: After IRB approval, 41 patients under the age of 17 who had MRa were identified. The following observations of contrast-filled clefts were assessed: (1) presence/absence, (2) location, (3) depth, (4) abnormal signal within the labrum and (5) shape (linear, gaping, complex). Fisher's exact and the Wilcoxon matched-pairs signed-rank test were performed. Interreader agreement was calculated with Cohen's k. RESULTS: Reader 1 found clefts in 41 %. Depth was less than half in 6%, more than half in 65% and full thickness in 29%. Shape was linear in 53%, gaping in 18% and complex in 29%. Signal changes occurred in 88%. Reader 2 found clefts in 29%. Depth was less than half in 17%, more than half in 58% and full thickness in 25%. Shape was linear in 50%, gaping in 42% and complex in 17%. Signal changes occurred in 50%. None of the clefts fulfilled the criteria for a sublabral sulcus at MRa and arthroscopy. CONCLUSION: None of the clefts found in our subjects under the age of 17 years met the MRa and arthroscopy criteria for a sublabral sulcus, which supports the theory that such clefts represent labral tears.

Aseptic hip pneumarthrosis following modular total hip arthroplasty: a potential mimic of hip infection.

Pneumarthrosis following total hip arthroplasty accompanied by acute hip symptoms is a potentially ominous finding suggesting infection with gas-forming bacteria, a medical emergency. We describe a case of a 61-year-old male presenting to the Emergency Department 43 months following a titanium/titanium (Ti/Ti) modular neck-stem total hip arthroplasty (MTHA) (Wright Medical Systems, Arlington, Tennessee) with acute presentation of hip symptoms and joint gas on radiographs proven to be aseptic hip pneumarthrosis. We review the imaging features of aseptic hip pneumarthrosis following MTHA which have not been elaborated on previously and suggest a less aggressive workup in select cases. We believe emergency radiologists should be aware of this unusual complication as it may mimic a septic hip which may entail an unnecessarily aggressive workup.

Ultrasound of the thigh: focal, compartmental, or comprehensive examination?

OBJECTIVE: Ultrasound of the thigh presents unique challenges because of the size and length of multiple structures, including tendons, muscles, nerves, and vessels. Those performing ultrasound can use a focal approach, a comprehensive approach, or a compartmental and flexible approach. CONCLUSION: This article illustrates and summarizes our approach to ultrasound of the thigh, including unique anatomy, artifacts, and common abnormalities, with an emphasis on the advantages of performing a compartment-based and flexible ultrasound examination.

MR imaging of the pelvis: a guide to incidental musculoskeletal findings for abdominal radiologists.

Occasionally patients who undergo magnetic resonance imaging for presumed pelvic disease demonstrate unexpected musculoskeletal imaging findings in the imaged field. Such incidental findings can be challenging to the abdominal radiologist, who may not be familiar with their appearance or know the appropriate diagnostic considerations. Findings can include both normal and abnormal bone marrow, osseous abnormalities such as Paget's disease, avascular necrosis, osteomyelitis, stress and insufficiency fractures, and athletic pubalgia, benign neoplasms such as enchondroma and bone island, malignant processes such as metastasis and chondrosarcoma, soft tissue processes such as abscess, nerve-related tumors, and chordoma, joint- and bursal-related processes such as sacroiliitis, iliopsoas bursitis, greater trochanteric pain syndrome, and labral tears, and iatrogenic processes such as bone graft or bone biopsy. Though not all-encompassing, this essay will help abdominal radiologists to identify and describe this variety of pelvic musculoskeletal conditions, understand key radiologic findings, and synthesize a differential diagnosis when appropriate.

Femoroacetabular cam-type impingement: global assessment of the femoral head-neck junction on a single reformatted MR image.

PURPOSE: To characterize the imaging appearance of femoral head-neck contour abnormalities on a short-axis magnetic resonance (MR) image compared with the usual anterior alpha angle measurements and multiple alpha angle measurements on radial reformatted MR images, with surgery as the reference standard. MATERIALS AND METHODS: After institutional review board approval of this HIPAA-compliant study, 21 patients who underwent arthroscopy and 24 patients who did not, all of whom were evaluated with three-dimensional MR imaging, during 1 year were identified. Short-axis MR images of the femoral head-neck junction were reformatted with multiple radial images along the axis of the femoral neck. The following measurements were made at each hour of a clock face: (a) presence and size of bone contour abnormality visible beyond a best-fit circle and (b) femoral head-neck offset angles. Mann-Whitney, Fisher exact, and Wilcoxon matched-pair signed rank tests were performed. Intra- and interreader agreement were calculated as the Cohen κ. RESULTS: Of the 21 subjects who underwent surgery, 16 were confirmed to have cam-type femoroacetabular impingement (FAI) at surgery. Comparing findings from short-axis images with those at surgery, average accuracy was 81%. Comparing findings from head-neck offset angles with those at surgery, average accuracy was 80%. On short-axis images, average bone elevation was 3.2 mm in patients with cam-type FAI and 1.4 mm in those without it. In eight of 24 subjects who did not undergo surgery, the alpha angle was normal but the short-axis MR image showed abnormal bone contour. CONCLUSION: An abnormal bone contour identified on a short-axis MR image at the femoral head-neck junction correlates with surgical findings and may allow for a global characterization of the bone abnormality with regard to location, extent, and amount of elevation compared with the alpha angle and multiple head-neck offset angles.

Value of ultrasound before joint aspiration.

OBJECTIVE: The purpose of this article is to illustrate and discuss the value of ultra-sound screening before joint aspiration. CONCLUSION: Before joint aspiration, ultrasound assessment of the overlying and surrounding soft tissues requires little time and is relatively inexpensive. Bursal fluid collections, soft-tissue abscesses, and other fluid collections that would be undetected with fluoroscopy or blind aspiration can thus be identified. Ultrasound screening before joint aspiration can aid diagnosis and decrease the risk of iatrogenic complications.

Morphology of large rotator cuff tears and of the rotator cable and long-term shoulder disability in conservatively treated elderly patients.

OBJECTIVE: The objective of this study was to describe the morphology of the rotator cuff tendon tears and long-term shoulder disability in conservatively treated elderly patients and determine if an association exists between these factors. METHODS: Assessment of the rotator cuff tendon tear dimensions and depth, rotator interval involvement, rotator cable morphology and location, and rotator cuff muscle status was carried out on magnetic resonance studies of 24 elderly patients treated nonoperatively for rotator cuff tendon tears. Long-term shoulder function was measured using the Western Ontario Rotator Cuff (WORC) index; Disabilities of the Shoulder, Arm, and Hand questionnaire; and the American Shoulder Elbow Self-assessment form, and a correlation between the outcome scores and morphologic magnetic resonance findings was carried out. RESULTS: The majority of large rotator cuff tendon tears are limited to the rotator cuff crescent. Medial rotator interval involvement (isolated or in association with lateral rotator interval involvement) was significantly associated with WORC physical symptoms total (P = 0.01), WORC lifestyle total (P = 0.04), percentage of all WORC domains (P = 0.03), and American Shoulder Elbow Self-assessment total (P = 0.01), with medial rotator interval involvement associated with an inferior outcome. CONCLUSIONS: Medial rotator interval tears are associated with long-term inferior outcome scores in conservatively treated elderly patients with large rotator cuff tendon tears.

Distal biceps brachii.

There has been a renewed interest in the recent literature with regard to the normal anatomy of the distal biceps tendon. Cadaveric studies have demonstrated that a large percentage of individuals have two independent muscle bellies, the short and the long head, with two distinct separate tendons attaching at the radial tuberosity. To avoid diagnostic errors that may have an impact on patient management in case of tendon injury, it is important to keep this anatomical variant in mind. Ultrasonography has been shown to be a useful imaging modality in the evaluation of disorders of the distal biceps brachii muscle and tendon. In this article, we review the relevant anatomy of the distal biceps brachii, the ultrasound technique with alternative approaches for optimum visualization of the distal tendon, and the most common pathologies in this region.