David M. Melville

Imaging Appearances in Gout

Gout is an ancient disease. Last decade has brought about significant advancement in imaging technology and real scientific growth in the understanding of the pathophysiology of gout, leading to the availability of multiple effective noninvasive diagnostic imaging options for gout and treatment options fighting inflammation and controlling urate levels. Despite this, gout is still being sub-optimally treated, often by nonspecialists. Increased awareness of optimal treatment options and an increasing role of ultrasound and dual energy computed tomography (DECT) in the diagnosis and management of gout are expected to transform the management of gout and limit its morbidity. DECT gives an accurate assessment of the distribution of the deposited monosodium urate (MSU) crystals in gout and quantifies them. The presence of a combination of the ultrasound findings of an effusion, tophus, erosion and the double contour sign in conjunction with clinical presentation may be able to obviate the need for intervention and joint aspiration in a certain case population for the diagnosis of gout. The purpose of this paper is to review imaging appearances of gout and its clinical applications.

High-Resolution US of Rheumatologic Diseases

For the past 15 years, high-resolution ultrasonography (US) is being routinely and increasingly used for initial evaluation and treatment follow-up of rheumatologic diseases. This imaging technique is performed by using high-frequency linear transducers and has proved to be a powerful diagnostic tool in evaluation of articular erosions, simple and complex joint and bursal effusions, tendon sheath effusions, and synovitis, with results comparable to those of magnetic resonance imaging, excluding detection of bone marrow edema. Crystal deposition diseases including gouty arthropathy and calcium pyrophosphate deposition disease (CPPD) have characteristic appearances at US, enabling differentiation between these two diseases and from inflammatory arthropathies. Enthesopathy, which frequently accompanies psoriatic and reactive arthritis, also has a characteristic appearance at high-resolution US, distinguishing these two entities from other inflammatory and metabolic arthropathies. The presence of Doppler signal in examined joints, bursae, and tendon sheaths indicates active synovitis. Microbubble echo contrast agents augment detection of tissue vascularity and may act in the future as a drug delivery vehicle. Frequently, joint, tendon sheath, and bursal fluid aspirations and therapeutic injections are performed under US guidance. The authors describe the high-resolution US technique including gray-scale, color or power Doppler, and contrast agent-enhanced US that is used in evaluation of rheumatologic diseases of the wrist and hand and the ankle and foot in their routine clinical practice. This article demonstrates imaging findings of normal joints, rheumatoid arthritis, gouty arthritis, CPPD, psoriatic and reactive arthritis, and osteoarthritis.

Shear-wave elastography: Basic physics and musculoskeletal applications

In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissues elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system. ©RSNA, 2017.

Artifacts in musculoskeletal ultrasonography.

During the past 2 decades, high-resolution ultrasonography (US) has been increasingly utilized in the diagnosis of musculoskeletal trauma and diseases with results comparable with MR imaging. US has an advantage over other cross-sectional modalities in many circumstances due to its superior spatial resolution and ability to allow dynamic assessment. When performing musculoskeletal US, the examiner has to be knowledgeable in the complex anatomy of the musculoskeletal system and US imaging technique. Additionally, he or she must be familiar with several common imaging artifacts in musculoskeletal US that may be mistaken for pathology, as well as several artifacts that frequently accompany pathologic conditions. These artifacts may occur with both B-mode gray-scale and Doppler imaging. In this article, we discuss common artifacts seen in musculoskeletal US and techniques to avoid or minimize these artifacts during clinical US examinations.

Imaging and management of thumb carpometacarpal joint osteoarthritis

Primary osteoarthritis (OA) involving the thumb carpometacarpal (CMC) joint is a common and frequently debilitating disease. Clinical examination and radiographs are usually sufficient for diagnosis; however, familiarity with the cross-sectional anatomy is useful for diagnosis of this condition. The most widely used classification system for the radiographic staging of thumb carpometacarpal joint OA was first presented by Eaton and Littler, ranging from mild (stages I and II) to severe (stage IV) disease. If conservative treatment fails, surgical treatment is considered. A variety of surgical techniques have been developed and implemented for the management of this pervasive and disabling condition. The purpose of this article is to review the anatomy of the basal joints of the thumb, pathophysiology, preoperative imaging, and various surgical techniques that are utilized in the treatment of OA of the basal joints of the thumb with emphasis on normal postoperative radiographic findings and possible postoperative complications.

Ultrasound of the Thumb Ulnar Collateral Ligament: Technique and Pathology

OBJECTIVE The ulnar collateral ligament (UCL) serves an important role in stabilizing the thumb metacarpophalangeal (MCP) joint. The adductor pollicis aponeurosis lies superficial to the UCL, and plays an important role in the pattern of injury and treatment of UCL tears. Ultrasound is a cost-effective and accurate method to evaluate the UCL, allowing dynamic imaging and contralateral comparison in the setting of acute injury. The purpose of this video article is to show the optimal technique for sonographic evaluation of the UCL. CONCLUSION UCL tears are common injuries involving the base of the thumb, and correct diagnosis of a Stener lesion aids in timely surgical management. Performing ultrasound evaluation in the long axis with use of dynamic imaging allows excellent visualization of the UCL and adductor pollicis aponeurosis. With application of appropriate technique, ultrasound is highly accurate in diagnosing Stener lesions.

Accuracy of High-Resolution Ultrasonography in the Detection of Extensor Tendon Lacerations

BackgroundLacerations to the extensor mechanism are usually diagnosed clinically. Ultrasound (US) has been a growing diagnostic tool for tendon injuries since the 1990s. To date, there has been no publication establishing the accuracy and reliability of US in the evaluation of extensor mechanism lacerations in the hand. The purpose of this study is to determine the accuracy of US to detect extensor tendon injuries in the hand. MethodsSixteen fingers and 4 thumbs in 4 fresh-frozen and thawed cadaveric hands were used. Sixty-eight 0.5-cm transverse skin lacerations were created. Twenty-seven extensor tendons were sharply transected. The remaining skin lacerations were used as sham dissection controls. One US technologist and one fellowship-trained musculoskeletal radiologist performed real-time dynamic US studies in and out of water bath. A second fellowship trained musculoskeletal radiologist subsequently reviewed the static US images. Dynamic and static US interpretation accuracy was assessed using dissection as “truth.” ResultsAll 27 extensor tendon lacerations and controls were identified correctly with dynamic imaging as either injury models that had a transected extensor tendon or sham controls with intact extensor tendons (sensitivity = 100%, specificity = 100%, positive predictive value = 1.0; all significantly greater than chance). Static imaging had a sensitivity of 85%, specificity of 89%, and accuracy of 88% (all significantly greater than chance). The results of the dynamic real time versus static US imaging were clearly different but did not reach statistical significance. ConclusionsDiagnostic US is a very accurate noninvasive study that can identify extensor mechanism injuries. Clinically suspected cases of acute extensor tendon injury scanned by high-frequency US can aid and/or confirm the diagnosis, with dynamic imaging providing added value compared to static. Ultrasonography, to aid in the diagnosis of extensor mechanism lacerations, can be successfully used in a reliable and accurate manner.

Multi-parametric MR imaging of quadriceps musculature in the setting of clinical frailty syndrome

ObjectiveFrailty is a common geriatric syndrome associated with loss of skeletal muscle mass (sarcopenia) conferring an increased risk of rapid decline in health and function with increased vulnerability to adverse outcomes. The purpose of this study was to investigate the correlation between diffusion tensor, T2 and intramuscular fat content values of the quadriceps muscle group and clinical frailty status using diffusion tensor MR imaging.Material and MethodsSubjects were recruited from the Arizona Frailty cohort composed of all females with frailty status based on the Fried criteria, including 6 non-frail and 10 pre-frail/frail adults, as well as a community sample of 11 young, healthy controls. Axial images of both thighs were obtained on a 3-T magnet with T1, T2 and diffusion tensor imaging as well as intramuscular fat analysis. Diffusion tensor and T2 values were determined by region-of-interest measurements at the proximal, mid and distal thirds of both thighs. Data were evaluated to determine differences between measured values and frailty status.ResultsThe mean fractional anisotropy (FA) values in the bilateral quadriceps muscles demonstrated significant differences (F = 7.558, p = 0.0030) between the control and pre-frail/frail and non-frail and pre-frail/frail groups. There was a significant difference in mean T2 (F = 21.675, p < 0.0001) and lipid content (F = 19.266, p < 0.0001) among all three groups in the total quadriceps muscle group.ConclusionThe quadriceps musculature of pre-frail/frail adults demonstrated increased FA compared to young controls and non-frail adults with increasing T2 and intramuscular fat among the control, non-frail and pre-frail/frail categories.

Ultrasound Evaluation of Morton Neuroma Before and After Laser Therapy

OBJECTIVE The objective of our study was to retrospectively assess for differences in imaging appearances of Morton neuromas before and after laser therapy using diagnostic ultrasound (US). MATERIALS AND METHODS A retrospective review was performed to identify patients who underwent US imaging to evaluate for Morton neuroma during the study period (June 1, 2013-July 1, 2014); of the 42 patients identified, 21 underwent US evaluations before and after laser therapy. US reports and images were reviewed and correlated with clinical history. The final study group consisted of 21 patients who had a total of 31 Morton neuromas evaluated using US after treatment. A retrospective review was then performed to characterize the appearances of these lesions before and after therapy followed by an analysis of variables. RESULTS Retrospective US review of 31 pretreatment Morton neuromas showed fusiform, heterogeneously hypoechoic masses with well-defined borders in most cases and that pain was reported when transducer pressure was applied in 97% (30/31) of cases. After treatment, lesions showed ill-defined borders (23/31), and pain with application of transducer pressure was either significantly decreased or absent (29/31); these findings were concordant with the clinical findings. Both of these characteristics were statistically significant (p < 0.0001). In addition, more Morton neuromas occurred in the second intermetatarsal space than in the third intermetatarsal space (p < 0.0001). CONCLUSION US may be used to identify posttreatment changes after laser therapy of Morton neuromas. Posttreatment changes include ill-defined borders and less pain or the absence of pain with the application of transducer pressure. These criteria may be applied in future clinical studies evaluating the efficacy of laser therapy for Morton neuroma.

Advances in Lower Extremity Ultrasound

AbstractDiagnostic ultrasound techniques used in the evaluation of the musculoskeletal system are rapidly evolving. Conventional B-mode and Doppler ultrasound imaging methods are workhorses in the diagnosis and treatment decision making for traumatic and pathologic conditions of joints, tendons, muscles, ligaments, and peripheral nerves. Recently developed sonoelastography techniques enable the qualitative and quantitative evaluation of the material properties of musculoskeletal tissues . The recent availability of sonoelastography on clinical machines will facilitate its progressive utilization in routine clinical practice. Exciting new developments in ultrasound imaging enable real-time fusion with imported magnetic resonance or computed tomography images, facilitating ultrasound-guided interventional procedures and teaching of ultrasound anatomy to trainees. In this review article, the authors discuss new advances in sonoelastography of the lower extremity with emphasis on shear wave imaging and briefly the exciting features of ultrasound fusion imaging with computed tomography and magnetic resonance imaging.