Alex W. H. Ng

Ultrasound of Musculoskeletal Soft-Tissue Tumors Superficial to the Investing Fascia

OBJECTIVE The objective of our study was to evaluate the diagnostic accuracy of ultrasound in assessing musculoskeletal soft-tissue tumors superficial to the investing fascia. MATERIALS AND METHODS Seven hundred fourteen superficial soft-tissue tumors evaluated with ultrasound by two musculoskeletal radiologists were retrospectively reviewed. In all ultrasound reports, the reporting radiologists provided one, two, or three diagnoses depending on their perceived level of diagnostic certainty. Two hundred forty-seven tumors had subsequent histologic correlation, thus allowing the accuracy of the ultrasound diagnosis to be determined. Images of the lesions with a discordant ultrasound diagnosis and histologic diagnosis were reviewed, and the ultrasound features were further classified as concordant with the known histologic diagnosis, concordant with the known histologic diagnosis with atypical features present, or discordant with the known histologic diagnosis. Four hundred sixty-seven tumors without pathologic confirmation were followed up clinically. RESULTS Overall the accuracy of ultrasound examination for assessing superficial soft-tissue masses was 79.0% when all differential diagnoses were considered and 77.0% when only the first differential diagnosis was considered. The sensitivity and specificity of the first ultrasound diagnosis were 95.2% and 94.3%, respectively, for lipoma; 73.0% and 97.7% for vascular malformation; 80.0% and 95.4% for epidermoid cyst; and 68.8% and 95.2% for nerve sheath tumor. Reduced observer awareness of specific tumor entities tended to contribute to underdiagnosis more than poor specificity of ultrasound findings. Most tumors (236/247, 96%) were benign. The sensitivity and specificity of ultrasound for identifying malignant superficial soft-tissue tumors was 94.1% and 99.7%, respectively. CONCLUSION The diagnostic accuracy of ultrasound in the assessment of superficial musculoskeletal soft-tissue tumors is high and can be improved through increased radiologist awareness of less frequently encountered tumors. Ultrasound is accurate for differentiating benign from malignant superficial soft-tissue tumors.

Assessment of capsular laxity in patients with recurrent anterior shoulder dislocation using MRI.

OBJECTIVE The purpose of our study was to investigate the usefulness of MRI in assessing capsular laxity in patients with recurrent shoulder dislocation. MATERIALS AND METHODS The records of 64 consecutive patients (the study group consisted of 58 patients, 45 male and 13 female; average age, 39.3 years; range, 13-82 years) who underwent MR arthrography between October 2002 and May 2008 were retrospectively reviewed. The patients were divided into three groups: group A, no shoulder dislocation; group B, first dislocation; and group C, recurrent dislocation. The maximum capsular widths at the anterior, anteroinferior, and inferior regions in the neutral and abducted and externally rotated (ABER) positions were measured on oblique sagittal images. The relationship of capsular width with the number of dislocations, type of capsular attachment, presence of anteroinferior labral tear, and patient sex were evaluated. The sensitivity and specificity of MRI and clinical tests in detecting capsular laxity were also calculated. RESULTS Among all three patient groups, there were significant differences (p < 0.05) in the widths with the shoulder in the ABER position and the degree of capsular tightening at the anterior region. The average maximum width was largest in group C and smallest in group A. There was a significant difference in the degree of anterior capsular tightening in groups B and C. A moderate correlation of capsular width and anterior tightening (R = -0.45) with number of shoulder dislocations was found. There was a significant difference in capsular width and capsular tightening in relation to the presence of an anteroinferior labral tear. The sensitivity and specificity to detect capsular laxity were 92% and 100%, respectively, for clinical tests and 85% and 96% for MRI. CONCLUSION MRI is a useful and objective method to assess capsular laxity in patients with recurrent shoulder dislocation.

Comparison of ultrasound versus fluorcoscopic guided rotator cuff interval approach for MR arthrography

Our purpose is to compare ultrasound and fluoroscopic-guided approaches to the glenohumeral joint at the rotator cuff interval for magnetic resonance (MR) arthrography of the shoulder. Forty consecutive patients were prospectively studied. 20 patients underwent ultrasound-guided and 20 patients underwent fluoroscopic guided injection. Successful rate of ultrasound guidance is 95%. No significant difference in pain score and duration of injection between two methods (P>.05). Ultrasound-guided rotator cuff interval injection of the glenohumeral joint for MR arthrography is comparable with fluoroscopic-guided injection. Ultrasound is the preferred method as there is no ionizing radiation.

Diagnostic capability of low- versus high-field magnetic resonance imaging for lumbar degenerative disease.

Study Design. Cohort study. Objective. To investigate the diagnostic capability of low-field magnetic resonance imaging (MRI) compared with high-field MRI for degenerative disease of the lumbar spine. Summary of Background Data. Low-field MRI has several advantages over high-field magnetic resonance systems (easier installation, lower purchase, and maintenance cost). The diagnostic capability of low-field MRI for degenerative disease of the lumbar spine has not been compared with that of high-field MRI. Methods. Hundred patients (mean age: 56.3 yr, range: 32–80; F:M = 59:41) with neurogenic claudication or sciatica were studied. All patients underwent MRI of the lumbar spine on both low-field (0.25T) and high-field (1.5T or 3.0T) magnetic resonance systems. Intervertebral disc herniation, central canal, lateral recess, and exit foraminal stenosis as well as nerve root compression at L3–L4, L4–L5, and L5–S1 were evaluated by 2 radiologists for both low- and high-field systems using established reliable grading systems. Results. There was excellent agreement between low- and high- field MRI with regard to grading the presence and severity of disc herniation (r = 0.92–0.94; P < 0.05), central canal stenosis (r = 0.89–0.91; P < 0.05), lateral recess stenosis (r = 0.81–0.87; P < 0.05), and exit foramen stenosis (r = 0.81–0.89; P < 0.05). Descending or exiting nerve root compression occurred in 52% of patients at L3–L4, L4–L5, or L5–S1 levels, with good agreement between low-field and high-field MRI (r = 0.71–0.76; P < 0.05) for nerve root compression. Conclusion. Excellent reliability between low- and high- field MRI was found for most features of lumbar disc degeneration, with good agreement for nerve root compression. 0.25T MRI was more susceptible to motion artifact, probably due to longer scanning time. Level of Evidence: 3

CT-Guided Bone Biopsy With a Battery-Powered Drill System: Preliminary Results

OBJECTIVE Standard percutaneous bone biopsy involves manual needle insertion. Recently, a battery-powered needle drilling biopsy system (OnControl) has been introduced. We report our experience using this drill biopsy system for CT-guided percutaneous bone biopsy in 25 patients. CONCLUSION CT-guided percutaneous biopsy using the OnControl bone access system is a safe, quick, and effective method for sampling bone lesions visible on CT.

Wrist Traction During MR Arthrography Improves Detection of Triangular Fibrocartilage Complex and Intrinsic Ligament Tears and Visibility of Articular Cartilage.

OBJECTIVE The purpose of this study was to assess the effects of traction during MR arthrography of the wrist on joint space widening, cartilage visibility, and detection of tears of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments. SUBJECTS AND METHODS A prospective study included 40 wrists in 39 patients (25 men, 14 women; mean age, 35 years). MR arthrography was performed with a 3-T MRI system with and without axial traction. Two radiologists independently measured wrist and carpal joint space widths and semiquantitatively graded articular cartilage visibility. Using conventional arthrography as the reference standard and working in consensus, they assessed for the presence of tears of the TFCC, lunotriquetral ligament (LTL), and scapholunate ligament (SLL). Visibility of a tear before traction was compared with visibility after traction. RESULTS With traction, all joint spaces in the wrist and carpus were significantly widened (change, 0.15-1.01 mm; all p < 0.006). Subjective cartilage visibility of all joint spaces improved after traction (all p ≤ 0.048) except for that of the radioscaphoid space, which was well visualized even before traction. Conventional arthrography depicted 24 TFCC tears, seven LTL tears, and three SLL tears. The accuracy of tear detection improved after traction for the TFCC (98% after traction vs 83% before traction), the LTL (100% vs 88%), and the SLL (100% vs 95%). Tear visibility improved after traction for 54% of TFCC tears, 71% of LTL tears, and 66% of SLL tears. CONCLUSION Wrist MR arthrography with axial traction significantly improved the visibility of articular cartilage and the detection and visibility of tears of the TFCC and intrinsic ligaments. The results favor more widespread use of traction during MR arthrography of the wrist.

Imaging of radial wrist pain. Part II: pathology

Pain on the radial side of the wrist is a common clinical presentation. Such wrist pain may provide a diagnostic challenge for radiologists, in view of the small size of the anatomic structures, the occasional subtlety of the imaging findings, the diversity of potential etiologies, as well as the non-infrequent occurrence of incidental asymptomatic findings in this area. This review discusses the imaging findings in both the more common and less common causes of radial-sided wrist pain, concentrating particularly on the detection of early disease and less readily apparent abnormalities.

Oblique axial MR imaging of the normal anterior cruciate ligament bundles

The anterior cruciate ligament (ACL) is composed of the anteromedial and posterolateral bundles [1, 2]. Although these two bundles are closely aligned anatomically, they do have distinct biomechanical functions with the anteromedial bundle stabilizing the knee in flexion and the posterolateral bundle stabilizing the knee in extension [1–5]. Most ACL tears are complete with the tear extending across both bundles. Partial tears of the ACL are less frequently encountered and may involve both bundles to a similar degree or one bundle predominantly. Although complete ACL tears do not have the capacity to heal, a limited blood supply to the ACL via the medial geniculate artery does allow healing of partial tears [6, 7]. Correct assessment regarding the presence, severity, and location of partial tears is relevant since delayed recognition of a partial tear can result in progression to complete tear [6]. Also, if only one bundle is predominantly torn, isolated single bundle reconstruction rather than full ACL graft reconstruction may be undertaken [8, 9]. Early evaluation of partial ACL tears could possibly improve clinical and surgical management [10]. A prerequisite to diagnosing ACL bundle injury on MR imaging is clear delineation of both bundles and awareness of their normal appearance. Orthogonal planes can delineate the normal ACL bundle structure in only 42% of knees [11]. In this study, we describe a new oblique axial plane for imaging the normal ACL bundles on MR imaging; evaluate how well the normal ACL bundles can be evaluated on this plane compared to the standard sagittal, coronal, and axial planes [12–15]; and describe the normal MR appearances.

Sonography of the chest wall: A pictorial essay

Ultrasound (US) is increasingly being used as the first‐line imaging modality for investigating the chest wall for soft tissue and bony lesions. This article describes the technique used for the US examination, the relevant chest‐wall anatomy, and the appearances on US scanning of pathologic entities either unique to or common in the region of the chest wall.

Imaging of radial wrist pain. I. Imaging modalities and anatomy

Radial wrist pain is a common clinical complaint. The relatively complex anatomy in this region, combined with the small size of the anatomical structures and occasionally subtle imaging findings, can pose problems when trying to localize the exact cause of pain. To fully comprehend the underlying pathology, one needs a good understanding of both radial-sided wrist anatomy and the relative merits of the different imaging techniques used to assess these structures. In part I of this review, these aspects will be discussed.