Developing an in situ LED irradiation system for small-angle X-ray scattering at B21, Diamond Light Source.

Beamline B21 at the Diamond Light Source synchrotron in the UK is a small-angle X-ray scattering (SAXS) beamline that specializes in high-throughput measurements via automated sample delivery systems. A system has been developed whereby a sample can be illuminated by a focused beam of light coincident with the X-ray beam. The system is compatible with the highly automated sample delivery system at the beamline and allows a beamline user to select a light source from a broad range of wavelengths across the UV and visible spectrum and to control the timing and duration of the light pulse with respect to the X-ray exposure of the SAXS measurement. The intensity of the light source has been characterized across the wavelength range enabling experiments where a quantitative measure of dose is important. Finally, the utility of the system is demonstrated via measurement of several light-responsive samples.

Diagnosis and treatment of flexor tendon injuries of the hand: what the radiologist needs to know.

This article reviews the diagnosis and treatment of flexor tendon injuries of the hand highlighting flexor tendon anatomy, important pre-operative imaging findings, surgical options, and post-operative complications. Imaging plays a key role in guiding treatment of these difficult to manage injuries. Thus, it is important for radiologists to have a sound understanding of factors important in treatment decision-making. In the pre-operative setting, accurately identifying the location of the torn proximal tendon stump in subacute and chronic injuries helps dictate whether the patient is a candidate for a primary flexor tendon repair or may require a tendon reconstruction to restore function. In the post-operative setting, the status of the repair and presence of surrounding adhesions help dictate if and when the patient will require subsequent surgery and whether that surgery will be a tenolysis, revision repair, reconstruction, or fusion.

Pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis: a case report.

Pronator syndrome is a median nerve entrapment neuropathy that can be difficult to diagnose due to its variable presentation and objective findings. Neurolymphomatosis is an uncommon disease in which malignant lymphocytes infiltrate central or peripheral nerve endoneurium and is often missed for prolonged periods prior to diagnosis. We present a rare case of pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis that was occult on initial MRI in spite of the presence of a median nerve mass discovered intra-operatively during neurolysis. This case demonstrates the value of ultrasound for the examination of peripheral nerve pathology and illustrates its utility as an adjunct to MRI, in part due to the ability to screen a large region.

Extended and weightbearing wrist 3-T MRI using a novel harness and flexible 24-channel glove coil to evaluate carpal kinematics: a pilot study in 10 volunteers.

BACKGROUND: Wrist pain in the extended or extended weightbearing positions may be incompletely evaluated using standard magnetic resonance imaging (MRI) with standard rigid clamshell coils in the neutral position. PURPOSE: To evaluate a flexible 24-channel glove coil and harness when imaging the wrist in neutral, dorsally extended, and weightbearing positions. MATERIAL AND METHODS: Ten wrists in 10 asymptomatic volunteers (mean age = 29 years) were scanned. Participants underwent 3-T MRI using the harness and flexible glove coil, acquiring sagittal turbo spin echo (TSE) and half-Fourier acquisition single-shot turbo spin echo (HASTE) pulse sequences. Static TSE images were obtained in neutral, extended, and weightbearing positions using proton density parameters and independently evaluated by two radiologists for: dorsal radiocarpal ligament thickness; radiocapitate, radiolunate, and capitatolunate angles; palmar translation of the lunate on the radius; angulation of the extensor tendons; and distance from the distal extensor retinaculum to Lister's tubercle. Cine HASTE images were dynamically acquired between neutral-maximum extension to measure the radiocapitate angle. RESULTS: Good reader agreement was observed (r > 0.73) for all measurements except palmar translation in the neutral position (r = 0.27). Significant increases in dorsal radiocarpal ligament thickness; radiocapitate, radiolunate and capitolunate angulation; and extensor tendon angulation were observed between the neutral and extended positions (P < 0.001). A further significant increase in these metrics between extended and weightbearing positions was also seen (P < 0.01). CONCLUSION: Significant increases in dorsal radiocarpal ligament thickness, articular and tendon angulations occur during wrist extension, that further increase with dorsal weightbearing.

Swinging injuries in competitive baseball players.

Injuries are common in competitive baseball players and can occur in all facets of the game. The majority of the existing literature on injuries in baseball players has focused on injuries secondary to the overhead throw with very little attention given to injuries sustained while batting. The baseball swing is a complex, often violent, motion that predisposes batters to a variety of injuries affecting the spine, trunk, pelvis, and extremities. Knowledge of injury patterns that commonly occur during the baseball swing and radiologic findings important to the treating physician can help radiologists provide accurate imaging interpretations that appropriately guide patient management.

Can MR neurography of the common peroneal nerve predict a residual motor deficit in patients with foot drop?

OBJECTIVE: To determine if MR neurography of the common peroneal nerve (CPN) predicts a residual motor deficit at 12-month clinical follow-up in patients presenting with foot drop. MATERIALS AND METHODS: A retrospective search for MR neurography cases evaluating the CPN at the knee was performed. Patients were included if they had electrodiagnostic testing (EDX) within 3 months of imaging, ankle and/or forefoot dorsiflexion weakness at presentation, and at least 12-month follow-up. Two radiologists individually evaluated nerve size (enlarged/normal), nerve signal (T2 hyperintense/normal), muscle signal (T2 hyperintense/normal), muscle bulk (normal/Goutallier 1/Goutallier > 1), and nerve and muscle enhancement. Discrepancies were resolved via consensus review. Multivariable logistical regression was used to evaluate for association between each imaging finding and a residual motor deficit at 12-month follow-up. RESULTS: Twenty-three 3 T MRIs in 22 patients (1 bilateral, mean age 52 years, 16 male) met inclusion criteria. Eighteen cases demonstrated common peroneal neuropathy on EDX, and median duration of symptoms was 5 months. Six cases demonstrated a residual motor deficit at 12-month follow-up. Fourteen cases underwent CPN decompression (1 bilateral) within 1 year of presentation. Three cases demonstrated Goutallier > 1 anterior compartment muscle bulk. Multivariable logistical regression did not show a statistically significant association between any of the imaging findings and a residual motor deficit at 12-month follow-up. CONCLUSION: MR neurography did not predict a residual motor deficit at 12-month follow-up in patients presenting with foot drop, though few patients demonstrated muscle atrophy in this study.

Ventricular arrhythmias in Kearns-Sayre syndrome: A cohort study using the National Inpatient Sample database 2016-2019.

BACKGROUND: Degeneration of the cardiac conduction system resulting in complete heart block (CHB), ventricular arrhythmias (VA), and sudden cardiac death (SCD) is recognized in patients with Kearns-Sayre syndrome (KSS) and is potentially preventable with permanent pacemaker (PPM) implantation. However, other mechanisms for SCD have been proposed, and the efficacy of implanting a defibrillator instead of PPM remains to be investigated. METHODS: We utilized the National Inpatient Sample (NIS) database 2016-2019 to investigate the risk of VA or dysrhythmic cardiac arrest (dCA) in KSS patients. We compared the outcomes of KSS to myotonic dystrophy (MD), a more common genetic disorder with similar clinical cardiac features and course. RESULTS: We identified 640 admissions for KSS. VA or dCA were lower in admissions for KSS than MD patients (2.3% vs. 4.5%, p = .009). Device implantation differed between study groups. Approximately, 70% of cases with KSS and conduction abnormalities had pacemaker (± defibrillator) on hospital discharge, compared to 35% in MD. Conduction abnormalities were associated with higher rates of VA or dCA in both study groups. None of the admissions for KSS patients who developed VA or dCA had a pacemaker, and all of them had conduction abnormalities. One-third of admissions for MD patients who developed VA or dCA had a device already implanted prior to the event. CONCLUSION: Despite its effectiveness in preventing VA, PPM remains underutilized in patients with KSS or MD who have conduction abnormalities. PPM alone do not fully prevent VA in MD patients; therefore, addition of defibrillator capacity might be necessary.

Nerve Imaging in the Wrist.

Neuropathic symptoms involving the wrist are a common clinical presentation that can be due to a variety of causes. Imaging plays a key role in differentiating distal nerve lesions in the wrist from more proximal nerve abnormalities such as a cervical radiculopathy or brachial plexopathy. Imaging complements electrodiagnostic testing by helping define the specific lesion site and by providing anatomical information to guide surgical planning. This article reviews nerve anatomy, normal and abnormal findings on ultrasonography and magnetic resonance imaging, and common and uncommon causes of neuropathy.

US-guided Musculoskeletal Interventions of the Body Wall and Core with MRI and US Correlation.

Chest, abdominal, and groin pain are common patient complaints that can be due to a variety of causes. Once potentially life-threatening visceral causes of pain are excluded, the evaluation should include musculoskeletal sources of pain from the body wall and core muscles. Percutaneous musculoskeletal procedures play a key role in evaluating and managing pain, although most radiologists may be unfamiliar with applications for the body wall and core muscles. US is ideally suited to guide these less commonly performed procedures owing to its low cost, portability, lack of ionizing radiation, and real-time visualization of superficial soft-tissue anatomy. US provides the operator with added confidence that the needle will be placed at the intended location and will not penetrate visceral or vascular structures. The authors review both common and uncommon US-guided procedures targeting various portions of the chest wall, abdominal wall, and core muscles with the hope of familiarizing radiologists with these techniques. Procedures include anesthetic and corticosteroid injection as well as platelet-rich plasma injection to promote tendon healing. Specific anatomic structures discussed include the sternoclavicular joint, costochondral joint, interchondral joint, intercostal nerve, scapulothoracic bursa, anterior abdominal cutaneous nerve, ilioinguinal nerve, iliohypogastric nerve, genitofemoral nerve, pubic symphysis, common aponeurotic plate, and adductor tendon origin. Relevant US anatomy is depicted with MRI correlation, and steps to performing successful safe US-guided injections are discussed. Confidence in performing these procedures will allow radiologists to continue to play an important role in diagnosis and management of many musculoskeletal pathologic conditions. ©RSNA, 2021.

3D MRI of the Shoulder.

Magnetic resonance imaging provides a comprehensive evaluation of the shoulder including the rotator cuff muscles and tendons, glenoid labrum, long head biceps tendon, and glenohumeral and acromioclavicular joint articulations. Most institutions use two-dimensional sequences acquired in all three imaging planes to accurately evaluate the many important structures of the shoulder. Recently, the addition of three-dimensional (3D) acquisitions with 3D reconstructions has become clinically feasible and helped improve our understanding of several important pathologic conditions, allowing us to provide added value for referring clinicians. This article briefly describes techniques used in 3D imaging of the shoulder and discusses applications of these techniques including measuring glenoid bone loss in anterior glenohumeral instability. We also review the literature on routine 3D imaging for the evaluation of common shoulder abnormalities as 3D imaging will likely become more common as imaging software continues to improve.

Imaging Evaluation of Medial and Lateral Elbow Pain: Acute and Chronic Tendon Injuries of the Humeral Epicondyles.

Medial and lateral elbow pain are often due to degenerative tendinosis and less commonly due to trauma. The involved structures include the flexor-pronator tendon origin in medial-sided pain and the extensor tendon origin in lateral-sided pain. Multimodality imaging is often obtained to verify the clinically suspected diagnosis, evaluate the extent of injury, and guide treatment decisions. Image-guided procedures can provide symptom relief to support physical therapy and also induce tendon healing. Surgical debridement and repair are typically performed in refractory cases, resulting in good to excellent outcomes in most cases. In this article, we review and illustrate pertinent anatomical structures of the distal humerus, emphasizing the structure and contributions of the flexor-pronator and extensor tendon origins in acute and chronic tendon abnormalities. We also discuss approaches to image-guided treatment and surgical management of medial and lateral epicondylitis.

Contrast-enhanced ultrasound-guided musculoskeletal biopsies: our experience and technique.

OBJECTIVE: To present our experience with contrast-enhanced ultrasound (CEUS)-guided musculoskeletal soft tissue biopsies in a busy interventional clinic. MATERIALS AND METHODS: After IRB approval was obtained and informed consent was waived, we retrospectively reviewed all CEUS-guided musculoskeletal biopsies performed from December 1, 2018 to March 2, 2020. Relevant pre-procedure imaging was reviewed. Number of samples, suspected necrosis on pre-procedure imaging, specimen adequacy for pathologic analysis, correlation with pathologic diagnosis of surgical resection specimens, and procedural complications were recorded. RESULTS: Thirty-six CEUS-guided musculoskeletal biopsies were performed in 32 patients (mean age 57, range 26-88; 22 males, 10 females). All procedures were performed using 16-gauge biopsy needles, and all procedures provided adequate samples for pathologic analysis as per the final pathology report. Between two and seven core specimens were obtained (mean 3.7). In 30/36 cases (83%), a contrast-enhanced MRI was obtained prior to biopsy, and 10/30 (33%) of these cases showed imaging features suspicious for necrosis. In 15/36 cases, surgical resection was performed, and the core biopsy and surgical resection specimens were concordant in 14/15 cases (93%). One patient noted transient leg discomfort at the time of microbubble bursting. Otherwise, no adverse reactions or procedural complications were observed. CONCLUSION: CEUS is an accurate way to safely target representative areas of soft tissue lesions for biopsy and can be implemented in a busy interventional clinic. Our early experience has shown this to be a promising technique, especially in targeting representative areas of heterogeneous lesions and lesions with areas of suspected necrosis on prior imaging.

Ultrasound-guided microwave ablation in the treatment of inguinal neuralgia.

Chronic groin pain can be due to a variety of causes and is the most common complication of inguinal hernia repair surgery. The etiology of pain after inguinal hernia repair surgery is often multifactorial though injury to or scarring around the nerves in the operative region, namely the ilioinguinal nerve, genital branch of the genitofemoral nerve, and the iliohypogastric nerve, is thought to be a key factor in causing chronic post-operative hernia pain or inguinal neuralgia. Inguinal neuralgia is difficult to treat and requires a multidisciplinary approach. Radiologists play a key role in the management of these patients by providing accurate image-guided injections to alleviate patient symptoms and identify the pain generator. Recently, ultrasound-guided microwave ablation has emerged as a safe technique, capable of providing durable pain relief in the majority of patients with this difficult to treat condition. The objectives of this paper are to review the complex nerve anatomy of the groin, discuss diagnostic ultrasound-guided nerve injection and patient selection for nerve ablation, and illustrate the microwave ablation technique used at our institution.

Intravenous contrast does not improve detection of nerve lesions or active muscle denervation changes in MR neurography of the common peroneal nerve.

OBJECTIVE: To evaluate the effect of intravenous (IV) contrast on sensitivity, specificity, and accuracy of magnetic resonance (MR) neurography of the knee with attention to the common peroneal nerve (CPN) in identifying nerve lesions and active muscle denervation changes. MATERIALS AND METHODS: A retrospective search for contrast-enhanced MR neurography cases evaluating the CPN at the knee was performed. Patients with electrodiagnostic testing (EDX) within 3 months of imaging were included and those with relevant prior surgery were excluded. Two radiologists independently reviewed non-contrast sequences and then 4 weeks later evaluated non-contrast and contrast sequences. McNemar's tests were performed to detect a difference between non-contrast only and combined non-contrast and contrast sequences in identifying nerve lesions and active muscle denervation changes using EDX as the reference standard. RESULTS: Forty-four exams in 42 patients (2 bilateral) were included. Twenty-eight cases had common peroneal neuropathy and 29, 21, and 9 cases had active denervation changes in the anterior, lateral, and posterior compartment/proximal muscles respectively on EDX. Sensitivity, specificity, and accuracy of non-contrast versus combined non-contrast and contrast sequences for common peroneal neuropathy were 50.0%, 56.2%, and 52.3% versus 50.0%, 56.2%, and 52.3% for reader 1 and 57.1%, 50.0%, and 54.5% versus 64.3%, 56.2%, and 61.4% for reader 2. Sensitivity, specificity, and accuracy of non-contrast and combined non-contrast and contrast sequences in identifying active denervation changes for anterior, lateral, and posterior compartment muscles were not significantly different. McNemar's tests were all negative. CONCLUSION: IV contrast does not improve the ability of MR neurography to detect CPN lesions or active muscle denervation changes.

A heuristic study of the similarities and differences in offender characteristics across potential and successful serial sexual homicide offenders.

This heuristic study examined potential serial sexual homicide offenders (SSHOs), an unacknowledged offender group comprised of aspiring and probable SSHOs, and compared them with successful SSHOs. Data were collected on six aspiring SSHOs who each failed a single homicide attempt, 16 probable SSHOs who committed 17 homicides in separate events, and 13 successful SSHOs who killed 90 victims in separate events. The study results indicate that while potential SSHOs share more in common with successful SSHOs than they do with single-victim nonsexual homicide offenders, and that there is an overlap between potential SSHOs and successful SSHOs, there is currently insufficient evidence to suggest that there are discreet transitions among categories. While few potential SSHOs strive to become successful SSHOs, this may be due to weak or nonexistent emotional triggers. Being a potential SSHO does not appear to be a predictable first step on a pathway towards becoming a successful SSHO, as potential SSHOs cannot reliably be thought of as prospective SSHOs if all things were equal. The present study could not foresee all potential SSHOs becoming successful ones. An as yet unidentified number of factors still appear to separate potential SSHOs from successful SSHOs.

Beamline B21: high-throughput small-angle X-ray scattering at Diamond Light Source.

B21 is a small-angle X-ray scattering (SAXS) beamline with a bending magnet source in the 3 GeV storage ring at the Diamond Light Source Ltd synchrotron in the UK. The beamline utilizes a double multi-layer monochromator and a toroidal focusing optic to deliver 2 × 1012 photons per second to a 34 × 40 µm (FWHM) focal spot at the in-vacuum Eiger 4M (Dectris) detector. A high-performance liquid chromatography system and a liquid-handling robot make it possible to load solution samples into a temperature-controlled in-vacuum sample cell with a high level of automation. Alternatively, a range of viscous or solid materials may be loaded manually using a range of custom sample cells. A default scattering vector range from 0.0026 to 0.34 Å-1 and low instrument background make B21 convenient for measuring a wide range of biological macromolecules. The beamline has run a full user programme since 2013.

The Lateral C1-C2 Puncture: Indications, Technique, and Potential Complications.

OBJECTIVE: Lateral C1-C2 puncture can be used for CSF collection, contrast agent injection for myelography, and access for cordotomy. The objective of this article is to describe the indications, technique, and potential complications of this procedure. CONCLUSION: Radiologists performing lumbar puncture or myelography should be comfortable gaining access to the subarachnoid space via the lateral C1-C2 approach when indicated. Familiarity with the technique and its potential complications is essential for a safe and efficient procedure.

Current Fixation Options for Elbow, Forearm, Wrist, and Hand Fractures.

The universal goals of upper limb fracture management are to restore anatomic alignment, establish stable fracture fixation (while preserving blood supply), and allow for early mobilization of the elbow, wrist, and digits. However, the indications for operative management and fixation constructs are specific to each fracture type. This article systematically reviews current classifications and treatment options for adult fractures of the distal humerus, radius, ulna, scaphoid, metacarpals, and phalanges. For each anatomic location, we discuss the salient imaging features to guide management decisions (conservative versus internal and/or external fixation). Specifically, we emphasize the amount of displacement, angulation, comminution, and/or intra-articular involvement typically guiding operative management for each fracture type. Through this understanding of the surgical indications, rationale behind different fixation options, and common complications, the radiologist can better support the orthopaedic surgeon via more informed fracture reporting.

Pseudoaneurysm after total knee arthroplasty: imaging findings in 7 patients.

OBJECTIVE: To describe the clinical presentation of arterial pseudoaneurysms following total knee arthroplasty (TKA) and their diagnostic imaging features on ultrasound and magnetic resonance angiography (MRA) in 7 patients. MATERIALS AND METHODS: A search of our radiology report database from 2007 to 2017 yielded 7 patients with a pseudoaneurysm diagnosed by imaging after TKA. Clinical notes and imaging were reviewed. RESULTS: All 7 patients were male and ranged in age from 53 to 68 (mean 61) years. All patients presented with a painful swollen knee and hemarthrosis within the first month following surgery. Five patients presented after primary TKA. One patient presented after explantation for septic arthritis and another after partial synovectomy for septic arthritis without explantation. Ultrasound identified the pseudoaneurysm as a hypoechoic or hyperechoic mass with a "yin-yang" appearance of turbulent arterial flow and associated complex joint effusion. On MRA, the pseudoaneurysm was a mass next to a parent artery showing avid contrast enhancement in the arterial phase that persisted into the venous phase and washed out in the late venous phase. Six pseudoaneurysms arose from lateral geniculate arteries and 1 from a medial geniculate artery. There were no popliteal artery pseudoaneurysms. Five patients were treated endovascularly, 1 patient thrombosed without intervention, and 1 patient was treated with open surgery. CONCLUSION: Pseudoaneurysm is a potential source of a painful swollen knee with hemarthrosis or a drop in hematocrit after TKA and can be identified with either ultrasound or MRA.

Imaging of the post-operative medial elbow in the overhead thrower: common and abnormal findings after ulnar collateral ligament reconstruction and ulnar nerve transposition.

Ulnar collateral ligament (UCL) reconstruction is now being performed more commonly and on younger patients than in prior decades. As a result, radiologists will increasingly be asked to evaluate elbow imaging of patients presenting with pain who have had UCL reconstruction. It is essential for radiologists to understand the normal and abnormal imaging appearances after UCL reconstruction and ulnar nerve transposition, which is also commonly performed in overhead-throwing athletes. Doing so will allow radiologists to provide accurate interpretations that appropriately guide patient management.