Pedro Augusto Gondim Teixeira

Adhesive Capsulitis of the Shoulder: Value of Inferior Glenohumeral Ligament Signal Changes on T2-Weighted Fat-Saturated Images

OBJECTIVE The objective of our study was to evaluate the performance of MRI for the diagnosis of adhesive capsulitis using signal intensity changes of the inferior glenohumeral ligament on T2-weighted fat-saturated sequences. MATERIALS AND METHODS MR images of 34 shoulders with a final clinical diagnosis of adhesive capsulitis were compared with those of an age-matched control group (34 shoulders) with no clinical signs of adhesive capsulitis. MR images were acquired before and after IV injection of gadolinium and were evaluated by two readers. The T2 signal intensity at the inferior glenohumeral ligament, the thickness of the coracohumeral ligament, and whether there was obliteration of subcoracoid fat were evaluated on unenhanced images. Enhancement at the inferior glenohumeral ligament and enhancement at the rotator interval were evaluated on contrast-enhanced images. The sensitivity, specificity, and interobserver variability of these signs were calculated. RESULTS T2 hyperintensity of the inferior glenohumeral ligament showed a high sensitivity (85.3-88.2%) and high specificity (88.2%) for the diagnosis of adhesive capsulitis with excellent interobserver variability (κ = 0.85). Signal analysis at the inferior glenohumeral ligament presented a higher sensitivity and a better interobserver agreement than the other signs of adhesive capsulitis evaluated. Gadolinium injection did not increase the performance of the inferior glenohumeral ligament signal analysis. An extracapsular hyperintense layer on T2-weighted images was identified as a new sign of adhesive capsulitis. CONCLUSION T2 capsular signal intensity change offers a high performance for the diagnosis of adhesive capsulitis without the need for IV or intraarticular contrast injection.

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician. J. Magn. Reson. Imaging 2011;33:2–16.

The nerves around the shoulder.

Neuropathies of the shoulder are considered to be entrapment syndromes. They are relatively common, accounting for about 2% of cases of sport-related shoulder pain. Many instances involve suprascapular neuropathy, but the clinical diagnosis is often delayed because of nonspecific symptoms. Classically, EMG is the gold standard investigation but MRI currently reveals muscular abnormality in 50% of cases. Muscle edema, the most characteristic symptom, is nonspecific. In general, the topography of edema, the presence of a lesion compressing the nerve and clinical history contribute to the diagnosis. Although atrophy and fatty degeneration may persist after the disappearance of edema, they are rarely symptomatic. The main differential diagnosis is Parsonage-Turner syndrome. Evidence of a cyst pressing on a nerve may prompt puncture-infiltration guided by ultrasonography or CT-scan.

Ultrasound assessment of the lateral collateral ligamentous complex of the elbow: imaging aspects in cadavers and normal volunteers

ObjectiveThe Lateral Collateral Ligamentous complex (LCL) is an important stabiliser of the elbow. It has a Y-shaped structure with three components. In this study, we sought to describe the ultrasound aspect of the individual components of this ligamentous complex and to evaluate the performance of ultrasound in both cadavers and in normal subjects.MethodsTen cadaveric elbow specimens underwent high-frequency ultrasound. Two specimens were sliced and two were dissected for anatomical correlation. Ten elbows of normal subjects were also evaluated by ultrasound. The findings were compared.ResultsThe three components of the LCL could be visualised in all specimens and normal subjects with the exception of the proximal portion of one specimen. In 80% of the specimens and 100% of the healthy volunteers the proximal portion of the LCL could be separated from the extensor tendons.ConclusionHigh-resolution ultrasound can assess all components of the LCL of the elbow and can distinguish them from surrounding structures.

Advanced Techniques in Musculoskeletal Oncology: Perfusion, Diffusion, and Spectroscopy

The imaging characterization of musculoskeletal tumors can be challenging, and a significant number of lesions remain indeterminate when conventional imaging protocols are used. In recent years, clinical availability of functional imaging methods has increased. Functional imaging has the potential to improve tumor detection, characterization, and follow-up. The most frequently used functional methods are perfusion imaging, diffusion-weighted imaging (DWI), and MR proton spectroscopy (MRS). Each of these techniques has specific protocol requirements and diagnostic pitfalls that need to be acknowledged to avoid misdiagnoses. Additionally, the application of functional methods in the MSK system has various technical issues that need to be addressed to ensure data quality and comparability. In this article, the application of contrast-enhanced perfusion imaging, DWI, and MRS for the evaluation of bone and soft tissue tumors is discussed, with emphasis on acquisition protocols, technical difficulties, and current clinical indications.

Musculoskeletal wide detector CT: Principles, techniques and applications in clinical practice and research

A progressive increase in the detector width in CT scanners has meant that advanced techniques such as dynamic, perfusion and dual-energy CT are now at the radiologists disposal. Although these techniques may be important for the diagnosis of various musculoskeletal diseases, data acquisition and interpretation can be challenging. This article offers a practical guide for the use of these tools including acquisition protocol, post-processing options and data interpretation based on 7 years of clinical experience in a tertiary university hospital.

Imaging of lower limb cartilage.

The cartilage of the lower limb joints is exposed to high levels of mechanical stress and therefore is a frequent site of degenerative and traumatic lesions. Magnetic resonance imaging (MRI) is the modality of choice for the assessment of these cartilage lesions. To date, clinically available sequences have focused on morphological defects and cartilage loss. Efforts have been made in recent years to depict cartilage lesions at an earlier stage, with new quantitative sequences focusing on the biochemical assessment of tissue. After a brief review of the hyaline cartilage structure, we review the current morphological imaging methods and the biochemical MRI techniques to assess the cartilage. We then illustrate the application of these MRI sequences for the most common degenerative and traumatic disorders affecting lower limb cartilage.

Impact of ROI Positioning and Lesion Morphology on Apparent Diffusion Coefficient Analysis for the Differentiation Between Benign and Malignant Nonfatty Soft-Tissue Lesions.

OBJECTIVE The objective of our study was to assess the impact of two methods of apparent diffusion coefficient (ADC) selection on the diagnostic performance of DWI in the characterization of nonfatty soft-tissue masses. SUBJECTS AND METHODS Sixty-five histologically confirmed soft-tissue tumors imaged from November 2009 through October 2012 were evaluated. The minimal ADC (ADCmin) and average ADC (ADCavg) values for each tumor were obtained using two ROI-positioning methods: manual and semiautomatic. Two readers correlated the findings to lesion histology and morphology on conventional MRI sequences. RESULTS The ADCmin values obtained using the manual method presented a better sensitivity with a similar specificity when compared with the ADCmin values obtained using the semiautomatic method (manual vs semiautomatic: 75-83% and 59-63% vs 58-67% and 63% and 63%, respectively). The interobserver agreement for the ADCmin values was similar between the ADC selection methods (intraclass correlation coefficient = 0.81 and 0.87 for manual and semiautomatic methods, respectively). In the subgroup of solid lesions, the ADCavg values obtained using the manual method offered a better sensitivity for benign-malignant differentiation (60-81% vs 60% and 60% for ADCavg and ADCmin, respectively). CONCLUSION The ADCmin values obtained with manual ROI positioning offered the best diagnostic performance for tumor characterization. The semiautomatic method yielded similar specificity values. For solid masses, the ADCavg values were better correlated with tumor histology than the ADCmin values.

Posterior Radioscaphoid Angle as a Predictor of Wrist Degenerative Joint Disease in Patients With Scapholunate Ligament Tears

OBJECTIVE The purpose of this study is to determine whether the posterior radioscaphoid angle, a marker of posterior displacement of the scaphoid, is associated with degenerative joint disease in patients with scapholunate ligament tears. MATERIALS AND METHODS Images from 150 patients with wrist pain who underwent CT arthrography and radiography were retrospectively evaluated. Patients with and without scapholunate ligament ruptures were divided into two groups according to CT arthrography findings. The presence of degenerative changes (scapholunate advanced collapse [SLAC] wrist) was evaluated and graded on conventional radiographs. Images were evaluated by two readers independently, and an adjudicator analyzed the discordant cases. Posterior radioscaphoid angle values were correlated with CT arthrography and radiographic findings. The association between posterior radioscaphoid angle and degenerative joint disease was evaluated. Scapholunate and radiolunate angles were considered in the analysis. RESULTS The posterior radioscaphoid angle was measurable in all patients, with substantial interobserver agreement (intraclass correlation coefficient, 0.75). The posterior radioscaphoid angle performed better than did the scapholunate and radiolunate angles in the differentiation of patients with and without SLAC wrist (p < 0.02). Posterior radioscaphoid angles greater than 114° presented an 80.0% sensitivity and 89.7% specificity for the detection of SLAC wrist. CONCLUSION Posterior radioscaphoid angles were strongly associated with degenerative wrist disease, with potential prognostic implications in patients with wrist trauma and scapholunate ligament ruptures.

The Impact of Dose Reduction in Quantitative Kinematic CT of Ankle Joints Using a Full Model-Based Iterative Reconstruction Algorithm: A Cadaveric Study

OBJECTIVE The objective of our study was to evaluate the quality and reproducibility of semiautomatic measurements of the ankle in low-dose kinematic CT studies using a full model-based iterative reconstruction (MBIR). MATERIALS AND METHODS Kinematic CT was performed in five cadaveric ankles at three acquisition dose levels: standard dose (1020 mGy × cm), low dose (10% of the standard dose), and ultra-low-dose (1.5% of the standard dose). All images were reconstructed using a full MBIR algorithm. Two semiautomatic measurements (one distance and one angle) were performed by two readers. Registration error was evaluated. The bone aspect on CT and presence of metallic implants were considered in the analysis. The influence of dose on the measurements obtained, reproducibility, and image quality was assessed. RESULTS With the standard- and low-dose protocols, registration quality was good (registration error, 0.65-4.72%), measurements were similar (p = 0.9), and reproducibility was excellent (intraclass correlation coefficient [ICC] = 0.881). With the ultra-low-dose protocol, the registration quality was poor, yielding measurements significantly different from the other protocols (p < 0.001) and poor reproducibility (ICC = 0.39). In a specimen with normal bone and no metal implant, the registration error was low (0.61-1.01%), measurements were similar (p > 0.5), and reproducibility was excellent (ICC, 0.885-0.996) for the three dose levels tested. CONCLUSION Full MBIR allows reliable and reproducible measurements in ankle kinematic CT with a low-dose protocol, but an ultra-low-dose protocol may lead to unreliable results.