CT Arthrography Research Articles

Optimization of Radiation Dose and Image Quality in Musculoskeletal CT: Emphasis on Iterative Reconstruction Techniques (Part 1).

Computed tomography (CT) is a modality of choice for the study of the musculoskeletal system for various indications including the study of bone, calcifications, internal derangements of joints (with CT arthrography), as well as periprosthetic complications. However, CT remains intrinsically limited by the fact that it exposes patients to ionizing radiation. Scanning protocols need to be optimized to achieve diagnostic image quality at the lowest radiation dose possible. In this optimization process, the radiologist needs to be familiar with the parameters used to quantify radiation dose and image quality. CT imaging of the musculoskeletal system has certain specificities including the focus on high-contrast objects (i.e., in CT of bone or CT arthrography). These characteristics need to be taken into account when defining a strategy to optimize dose and when choosing the best combination of scanning parameters. In the first part of this review, we present the parameters used for the evaluation and quantification of radiation dose and image quality. In the second part, we discuss different strategies to optimize radiation dose and image quality at CT, with a focus on the musculoskeletal system and the use of novel iterative reconstruction techniques.

Optimization of Radiation Dose and Image Quality in Musculoskeletal CT: Emphasis on Iterative Reconstruction Techniques (Part 2).

Computed tomography (CT) is a modality of choice for the study of the musculoskeletal system for various indications including the study of bone, calcifications, internal derangements of joints (with CT arthrography), as well as periprosthetic complications. However, CT remains intrinsically limited by the fact that it exposes patients to ionizing radiation. Scanning protocols need to be optimized to achieve diagnostic image quality at the lowest radiation dose possible. In this optimization process, the radiologist needs to be familiar with the parameters used to quantify radiation dose and image quality. CT imaging of the musculoskeletal system has certain specificities including the focus on high-contrast objects (i.e., in CT of bone or CT arthrography). These characteristics need to be taken into account when defining a strategy to optimize dose and when choosing the best combination of scanning parameters. In the first part of this review, we present the parameters used for the evaluation and quantification of radiation dose and image quality. In the second part, we discuss different strategies to optimize radiation dose and image quality of CT, with a focus on the musculoskeletal system and the use of novel iterative reconstruction techniques.

Dual-Energy CT: Basic Principles, Technical Approaches, and Applications in Musculoskeletal Imaging (Part 1).

In recent years, technological advances have allowed manufacturers to implement dual-energy computed tomography (DECT) on clinical scanners. With its unique ability to differentiate basis materials by their atomic number, DECT has opened new perspectives in imaging. DECT has been used successfully in musculoskeletal imaging with applications ranging from detection, characterization, and quantification of crystal and iron deposits; to simulation of noncalcium (improving the visualization of bone marrow lesions) or noniodine images. Furthermore, the data acquired with DECT can be postprocessed to generate monoenergetic images of varying kiloelectron volts, providing new methods for image contrast optimization as well as metal artifact reduction. The first part of this article reviews the basic principles and technical aspects of DECT including radiation dose considerations. The second part focuses on applications of DECT to musculoskeletal imaging including gout and other crystal-induced arthropathies, virtual noncalcium images for the study of bone marrow lesions, the study of collagenous structures, applications in computed tomography arthrography, as well as the detection of hemosiderin and metal particles.

Dual-Energy CT: Basic Principles, Technical Approaches, and Applications in Musculoskeletal Imaging (Part 2).

In recent years, technological advances have allowed manufacturers to implement dual-energy computed tomography (DECT) on clinical scanners. With its unique ability to differentiate basis materials by their atomic number, DECT has opened new perspectives in imaging. DECT has been successfully used in musculoskeletal imaging with applications ranging from detection, characterization, and quantification of crystal and iron deposits, to simulation of noncalcium (improving the visualization of bone marrow lesions) or noniodine images. Furthermore, the data acquired with DECT can be postprocessed to generate monoenergetic images of varying kiloelectron volts, providing new methods for image contrast optimization as well as metal artifact reduction. The first part of this article reviews the basic principles and technical aspects of DECT including radiation dose considerations. The second part focuses on applications of DECT to musculoskeletal imaging including gout and other crystal-induced arthropathies, virtual noncalcium images for the study of bone marrow lesions, the study of collagenous structures, applications in computed tomography arthrography, as well as the detection of hemosiderin and metal particles.

Is transverse acetabular ligament a reliable guide for aligning cup anteversion in total hip arthroplasty?: A measurement by CT arthrography in 90 hips.

Transverse acetabular ligament (TAL) has been used as a landmark for aligning cup anteversion. The use of TAL as a guide is based on the assumption that TAL version is distributed within the safe zone of acetabular cup. However, there was rarely reported to compare anteversion between TAL and acetabulum using direct measurement methods. The purpose of this study was to measure the anteversion of TAL in computed tomography arthrography (CTA) and compare it with Lewinnek's safe zone and anteversion of bony acetabulum. 81 patients (90 hips) were selected among 204 patients (228 hips) who received CTA for hip pathology evaluation between March 2010 and June 2013. The anteversion of TAL measured at the lowest level of the acetabular notch and the anteversion of the acetabulum was measured at the level of femoral head center. The mean TAL anteversion was 11.8° (SD 4.5, range 0-22.2). In eight hips (8.8%), TAL anteversion was outside the safe zone (15°±10°) as defined by Lewinnek. The mean acetabular anteversion was 13.3° ± 4.4° (range-1.0° to 22.6°). There was a strong correlation between TAL anteversion and acetabular anteversion (Pearson's correlation coefficient; 0.908, p<0.001). TAL anteversion has a large individual variation, and considerable portion of hips have TAL anteversion outside the safety zone of cup anteversion. TAL anteversion is influenced by acetabular anteversion. In hips with retroverted or pauci-anteverted acetabulum, TAL should be used cautiously because there is a risk of cup malposition.

Surgical Results of Delaminated Rotator Cuff Repair Using Suture-Bridge Technique With All-Layers or Bursal Layer–Only Repair

Background: There are no known studies that have investigated the effect on delaminated rotator cuff tears of bursal layer–only repair when full-thickness repair would put the articular layer under tension, compared with all-layers repair when full-thickness repair is feasible. Hypothesis: Better outcomes will be seen in the bursal layer–only repair, as the articular layer would be under tension when repaired onto its footprint during the all-layers repair. Study Design: Cohort study; Level of evidence 3. Methods: This study included 112 patients who underwent arthroscopic rotator cuff repair for posteriorly delaminated tears of either all layers (group A) or the bursal layer alone (group B). If the articular layer was able to be reduced onto its footprint, the patient was assigned to group A; if such reduction was not possible or was only marginally possible under significant tension, the patient was assigned to group B. Pain scored on a visual analog scale (VAS) was assessed, as were subjective shoulder value (SSV), University of California, Los Angeles (UCLA) shoulder score, American Shoulder and Elbow Surgeons (ASES) score, and shoulder active range of motion (ROM). Postoperative magnetic resonance arthrography (MRA) or computed tomographic arthrography (CTA) was undertaken 6 months postoperatively for structural integrity assessment. Results: After 2 years, the VAS pain score (group A, from 6.5 to 1.2; group B, from 6.4 to 1.2), SSV (group A, from 38.3 to 89.4; group B, from 38.0 to 90.1), ASES score (group A, from 36.4 to 90.4; group B, from 38.0 to 90.8), UCLA shoulder score (group A, from 15.3 to 30.7; group B, from 15.0 to 31.3), and ROM improved significantly in both groups compared with preoperative values (P < .001). However, none of these values differed significantly between groups. On follow-up MRA or CTA images, there was no significant difference in the retear rate between group A (28%; 16/57) and group B (24%; 11/45). Conclusion: The all-layers repair did not produce better clinical outcomes or structural integrity than the bursal layer–only repair. The study findings indicate that if repair of the articular layer is possible only under significant tension or is not reparable, rather than all-layers repair by force, bursal-layer repair without incorporating the articular layer may produce comparable clinical outcomes and structural integrity in the delaminated rotator cuff tear.

Shape-based acetabular cartilage segmentation: application to CT and MRI datasets.

A new method for acetabular cartilage segmentation in both computed tomography (CT) arthrography and magnetic resonance imaging (MRI) datasets with leg tension is developed and tested. The new segmentation method is based on the combination of shape and intensity information. Shape information is acquired according to the predictable nonlinear relationship between the U-shaped acetabulum region and acetabular cartilage. Intensity information is obtained from the acetabular cartilage region automatically to complete the segmentation procedures. This method is evaluated using 54 CT arthrography datasets with two different radiation doses and 20 MRI datasets. Additionally, the performance of this method in identifying acetabular cartilage is compared with four other acetabular cartilage segmentation methods. This method performed better than the comparison methods. Indeed, this method maintained good accuracy level for 74 datasets independent of the cartilage modality and with minimum user interaction in the bone segmentation procedures. In addition, this method was efficient in noisy conditions and in detection of the damaged cartilages with zero thickness, which confirmed its potential clinical usefulness. Our new method proposes acetabular cartilage segmentation in three different datasets based on the combination of the shape and intensity information. This method executes well in situations where there are clear boundaries between the acetabular and femoral cartilages. However, the acetabular cartilage and pelvic bone information should be obtained from one dataset such as CT arthrography or MRI datasets with leg traction.

Assessment of painful total shoulder arthroplasty using computed tomography arthrography

This study assessed the accuracy of computed tomography (CT) arthrography when evaluating glenoid component stability in the setting of postarthroplasty shoulder pain. We retrospectively reviewed all patients presenting to the clinic during a 5.5-year period to identify those with a painful shoulder arthroplasty more than 1 year after the index procedure. We excluded reverse and hemiarthroplasty procedures, patients with a clearly identifiable cause for pain, such as rotator cuff insufficiency or gross component loosening as seen on plain radiographs, and those with culture-positive aspiration. There were 14 patients with suspected glenoid component loosening but inconclusive plain radiographs. Each of the 14 patients underwent a CT arthrogram that was evaluated by the senior author (J.J.P.W.) for the presence or absence of contrast material underneath the polyethylene component. Operative reports and surgical videos from subsequent arthroscopy were reviewed to assess glenoid component stability as determined by direct arthroscopic visualization. CT arthrography suggested glenoid component loosening in 8 of 14 patients (57.1%), and arthroscopic inspection identified loosening in 10 of 14 patients (71.4%). In 3 of 10 patients (30%), CTA suggested a well-fixed glenoid component, but gross loosening was identified during arthroscopy. In this study, CTA yielded a sensitivity of 70%, a specificity of 75%, a positive predictive value of 87.5%, and a negative predictive value of 50.0%. CTA had a low negative predictive value (50%), and therefore, the prediction of component stability based on the absence of contrast between the glenoid component and the bone-cement interface does not always reflect true stability.

Advanced imaging of the scapholunate ligamentous complex.

The scapholunate joint is one of the most involved in wrist injuries. Its stability depends on primary and secondary stabilisers forming together the scapholunate complex. This ligamentous complex is often evaluated by wrist arthroscopy. To avoid surgery as diagnostic procedure, optimization of MR imaging parameters as use of three-dimensional (3D) sequences with very thin slices and high spatial resolution, is needed to detect lesions of the intrinsic and extrinsic ligaments of the scapholunate complex. The paper reviews the literature on imaging of radial-sided carpal ligaments with advanced computed tomographic arthrography (CTA) and magnetic resonance arthrography (MRA) to evaluate the scapholunate complex. Anatomy and pathology of the ligamentous complex are described and illustrated with CTA, MRA and corresponding arthroscopy. Sprains, mid-substance tears, avulsions and fibrous infiltrations of carpal ligaments could be identified on CTA and MRA images using 3D fat-saturated PD and 3D DESS (dual echo with steady-state precession) sequences with 0.5-mm-thick slices. Imaging signs of scapholunate complex pathology include: discontinuity, nonvisualization, changes in signal intensity, contrast extravasation (MRA), contour irregularity and waviness and periligamentous infiltration by edema, granulation tissue or fibrosis. Based on this preliminary experience, we believe that 3T MRA using 3D sequences with 0.5-mm-thick slices and multiplanar reconstructions is capable to evaluate the scapholunate complex and could help to reduce the number of diagnostic arthroscopies.

Injuries of the scapholunate and lunotriquetral ligaments as well as the TFCC in intra-articular distal radius fractures. Prevalence assessed with MDCT arthrography.

To evaluate the prevalence of injuries of the scapholunate and lunotriquetral interosseous ligaments (SLIL, LTIL) as well as the triangular fibrocartilage complex (TFCC) in intra-articular distal radius fractures (iaDRF). Two hundred and thirty-three patients with acute iaDRF underwent MDCT arthrography. The SLIL and LTIL were described as normal, partially or completely ruptured. Major injuries of the SLIL were defined as completely ruptured dorsal segments, those of the LTIL as completely ruptured palmar segments. The TFCC was judged as normal or injured. Interobserver variability was calculated. Injury findings were correlated with the types of iaDRF (AO classification). In 159 patients (68.2 %), no SLIL injuries were seen. Minor SLIL injuries were detected in 54 patients (23.2%), major injuries in 20 patients (8.6%). No correlation was found between the presence of SLIL lesions and the types of iaDRF. Minor LTIL injuries were seen in 23 patients (9.9%), major injuries in only 5 patients (2.2%). The TFCC was altered in 141 patients (60.5%). Interobserver variability was high for MDCT arthrography in assessing SLIL and TFC lesions, and fair for LTIL lesions. In iaDRF, prevalence of major injuries of the most relevant SLIL is about 9% as evaluated with CT arthrography. The C-shaped SLIL is built of dorsal, middle and palmar segments. In iaDRF, major SLIL injuries are associated in 8.6% of the cases. In iaDRF, the SLIL remains intact in 68.3% of the cases. IaDRF and SLIL ruptures can comprehensively be depicted with MDCT arthrography. A three-compartment approach is recommended to assess intrinsic ligaments and the TFCC.

Superior Labral Cleft after Superior Labral Anterior-to-Posterior Tear Repair: CT Arthrographic Features and Correlation with Clinical Outcome

To evaluate the presence of a superior labral cleft at postoperative computed tomographic (CT) arthrography after superior labral anterior-to-posterior lesion (SLAP) repair and to correlate CT arthrographic appearance with clinical outcomes. The institutional review board approved this retrospective study, and the requirement to obtain informed consent was waived. Fifty-six patients who underwent CT arthrography after arthroscopic SLAP repair were included. Two musculoskeletal radiologists retrospectively reviewed CT arthrographic images for the presence, size, location, direction, and shape of a superior labral cleft, which was defined as a detectable contrast material-filled focal discontinuity of the labrum within anchor fixation sites of the glenoid. In addition, the glenoid osteolysis ratio was calculated on the basis of the CT arthrographic images. Clinical outcome was evaluated with use of the American Shoulder and Elbow Surgeons (ASES) scoring system. Continuous variables, such as patient age, interval between imaging and surgery, ASES score, and osteolysis ratio, were compared by using the Mann-Whitney U test. A superior labral cleft was observed in 27 of the 56 patients (48%). The mean width and depth of the superior labral clefts was 2.1 mm ± 1.1 and 2.8 mm ± 0.8, respectively. The superior labral clefts extended posterior to the biceps anchor in 16 of the 27 patients (59%), were curved medially in 24 (89%), and had a smooth margin in 22 (81%). No significant association was observed between the presence of a superior labral cleft and the ASES score (P = .805) or patient age (P = .290). Superior labral clefts were observed more commonly in cases with a long interval since surgery (P = .007) and a high osteolysis ratio (P = .011). Superior labral clefts are frequently observed on CT arthrographic images after arthroscopic SLAP repair and do not correlate with clinical outcome.

Epinephrine-enhanced computed tomographic arthrography of the canine shoulder

The aim of this study was to investigate the effect of epinephrine-enhanced computed tomographic arthrography (CTA) on the image sharpness of the lateral and medial glenohumeral ligaments (LGHL and MGHL, respectively), biceps tendon (BT) and joint cartilage (JC) in the canine shoulder.The shoulders of eight normal dogs were examined using a 4-slice helical CT scanner. The right shoulders were injected with Iohexol and the left shoulders with a mixture of Iohexol and epinephrine. CTA images were obtained after 1, 3, 5, 9, 13, 20 and 30min and the image sharpness of the intra-articular structures in both shoulders was graded for visibility. The attenuation values were measured to examine the persistence of contrast appearance. Admixture of epinephrine and Iohexol significantly improved the image sharpness of the LGHL and the BT, especially on delayed CTA images. The use of epinephrine did not negatively affect post-CTA recovery.

Accuracy assessment of 3D bone reconstructions using CT: an intro comparison

Computed tomography provides high contrast imaging of the joint anatomy and is used routinely to reconstruct 3D models of the osseous and cartilage geometry (CT arthrography) for use in the design of orthopedic implants, for computer assisted surgeries and computational dynamic and structural analysis. The objective of this study was to assess the accuracy of bone and cartilage surface model reconstructions by comparing reconstructed geometries with bone digitizations obtained using an optical tracking system. Bone surface digitizations obtained in this study determined the ground truth measure for the underlying geometry. We evaluated the use of a commercially available reconstruction technique using clinical CT scanning protocols using the elbow joint as an example of a surface with complex geometry. To assess the accuracies of the reconstructed models (8 fresh frozen cadaveric specimens) against the ground truth bony digitization—as defined by this study—proximity mapping was used to calculate residual error. The overall mean error was less than 0.4 mm in the cortical region and 0.3 mm in the subchondral region of the bone. Similarly creating 3D cartilage surface models from CT scans using air contrast had a mean error of less than 0.3 mm. Results from this study indicate that clinical CT scanning protocols and commonly used and commercially available reconstruction algorithms can create models which accurately represent the true geometry.

Multirater agreement for grading the femoral and tibial cartilage surface lesions at CT arthrography and analysis of causes of errors

Multirater agreement for grading the femoral and tibial cartilage surface lesions at CT arthrography and analysis of causes of errors

Value of future epidemiologic research in OA: The art and science of selecting an appropriate study design

s / Osteoarthritis and Cartilage 23 (2015) A17eA25 A23 diffusion-weighted imaging. Evaluation of the glycosaminoglycan (GAG) matrix in cartilage can be done with delayed gadolinium enhanced MRI of cartilage (dGEMRIC), T1rho relaxation time measurements, sodium MRI, and chemical exchange saturation transfer (gagCEST). In addition, evaluation of cartilage and other tissues under load (biomechanics) is also possible with MRI. All of these method have advantages and drawbacks that may make them more appropriate to a given imaging situation or study. Conclusions: A variety of MRI methods to evaluate a joint with osteoarthritis are available. The methods of choice in a particular study depend on many factors, including hardware available, the joint being studied, and imaging time. Emphasis will be placed on the trade-offs between the methods and goals of the imaging study. Study of tissue composition with MRI may be particularly helpful in disease initiation. Once OA is established, study of tissue morphology with MRI can be done quantitatively or with semi-quantitative scoring. I-23 VALUE OF FUTURE EPIDEMIOLOGIC RESEARCH IN OA: THE ART AND SCIENCE OF SELECTING AN APPROPRIATE STUDY DESIGN E. Losina. Boston Univ. Sch. of Publ. Hlth., Boston, MA, USA During the session we will discuss how to optimize the study design and to ensure it enables researchers to offer a new informative insight toward the clinical question under study.Wewill discuss how to choose among several clinical questions to optimize the likely impact of future research study. We will address the topics of resource prioritization. In addition the audience will be introduced to the concept of Value of Information. We will also cover use and misuse several commonly used statistical methods in analysis of clinical studies in OA. I-24 CURRENT STATUS OF THE ART IN COMPOSITIONAL IMAGING OF JOINT TISSUES T.M. Link. Univ. of California San Francisco, San Francisco, CA, USA Purpose: To review technologies currently used to assess the biochemical composition of joint tissues and discuss their pros and cons. Methods available: During the last decade a number of compositional technologies have been established and studied mostly using quantitative MRI. These include T2 mapping, T1rho, dGEMRIC (delayed Gadolinium enhanced MRI of the cartilage), Sodium-23-imaging and gagCEST (glycosaminoglycan chemical exchange saturation transfer) imaging to quantify cartilage andmeniscal biochemical composition. T2 mapping is currently the most widely used technology and most information is available on this imaging biomarker, which provides quantitative data on water content and collagen integrity of the cartilage and menisci. According to previous in vitro studies T1rho characterizes the amount of macromolecules within the tissue, which correlates with the amount of proteoglycans. dGEMRIC requires the injection of negatively charged Gadolinium contrast agents which provide quantitative information on the amount of negatively charged glycosaminoglycans. Both Sodium imaging and gagCEST target the concentration of glycosaminoglycans, but require imaging at higher field strength. Quantitative CT has also been used in vivo to assess glycosaminoglycan concentration in hyaline cartilage but it requires the injection of contrast agents into the joint and there is radiation exposure. Results of previous studies: Previous studies showed that imaging biomarkers of cartilage composition had good reproducibility and validated these biomarkers both in an in vitro setting and clinically. In 2011 a multi-center ACRIN trial was published which documented that in a Multi-Center, Multivendor environment knee cartilage T2, and patellar T1-rho demonstrated moderate to excellent reproducibility (1). Similarly phantom measurements over 8 years in the Osteoarthritis Initiative environment showed good reproducibility of T2 relaxation times varying from 1.5 to 5.3% (2). Single center studies found good reproducibilities for dGEMRIC while less consistent data is available for some the newer techniques such as gagCEST and quantitative CT arthrography. In vitro studies showed that T1rho, T2 and dGEMRIC measurements correlated with histological assays of proteoglycan and collagen as well as mechanical properties of cartilage (3, 4). Clinical studies documented differences in T1rho, T2 and dGEMRIC measurements between patients with early osteoarthritis and normal controls and one recent study showed that T2 measurements predicted radiographic onset of knee osteoarthritis in a longitudinal study from the OAI (5). Longitudinal studies also showed that T2 measurements increased over time in normal populations, and were sensitive to weight loss and physical activity. Problems, however, have been found in using measures of cartilage composition in more advanced degenerative disease. Conclusion: A number of imaging biomarkers of joint composition are available, which have been validated and shown to have good reproducibility. T1rho, T2 and dGEMRIC are currently the imaging biomarkers, which are best established with most studies having been performed using T2 relaxation time measurements.

Age-related Outcome of Arthroscopic Repair of Isolated Type II Superior Labral Anterior to Posterior Lesions

Background: Repair of superior labral anterior to posterior (SLAP) lesion in patients older than 40 years is controversial. The purpose of this study was to evaluate clinical outcomes of arthroscopic repair of SLAP lesions between younger and older patient groups. Methods: We reviewed 50 patients with isolated type II SLAP lesions who underwent arthroscopic repair. Patients were divided into 2 groups: group 1 included 20 patients aged Results: No significant differences in functional scores or postoperative ROM were observed between the 2 groups. In group 2, later recovery of ROM (forward flexion, p=0.025; internal rotation, p=0.034) and lower satisfaction score (p=0.06) were observed for atraumatic patients (n=16) compared to patients with traumatic injury (n=14). Fifteen patients in group 1 (15/17, 88%) and 21 patients in group 2 (21/26, 81%) demonstrated a healed labrum on postoperative CT arthrography, and this difference was not significant. Conclusions: The results of this study suggest that arthroscopic repair of type II SLAP lesions can yield good functional and anatomical outcomes regardless of age, if patient selection is adequate. However, the delay in ROM recovery and lower satisfaction, particularly in older patients without traumatic injury, should be considered.

Clinical or radiological diagnosis of impingement

Shoulder impingement syndrome is a clinically common entity involving trapping of tendons or bursa with typical clinical findings. Important radiological procedures are ultrasound, magnetic resonance imaging (MRI) and MR arthrography. Projection radiography and computed tomography (CT) are ideal to identify bony changes and CT arthrography also serves as an alternative method in cases of contraindications for MRI. These modalities support the clinically suspected diagnosis of impingement syndrome and may identify its cause in primary diagnosis. In addition, effects of impingement are determined by imaging. Therapy decisions are based on a synopsis of radiological and clinical findings. The sensitivity and specificity of these imaging modalities with regard to the diagnostics of a clinically evident impingement syndrome are given in this review article. Orthopedic and trauma surgeons express the suspicion of an impingement syndrome based on patient history and physical examination and radiologists confirm structural changes and damage of intra-articular structures using dedicated imaging techniques.

Tears at the myotendinous junction of the infraspinatus: ultrasound findings.

Tears involving the myotendinous junction (MTJ) of the infraspinatus (IS) have been recently described on MRI. These occur centrally in the muscle belly, and are not associated with full thickness tears of the distal infraspinatus tendon. They also induce a rapidly progressive fatty infiltration of the muscles and amyotrophy. The purpose of this study is to assess the accuracy of ultrasonography in diagnosing MTJ tears of the infraspinatus and to describe the usual ultrasonographic appearance compared with MRI. Retrospective study of 2403 US examinations of the shoulder (over 5 years). Fifteen patients with a reported suspicion of infraspinatus MTJ tears were included. MRI examination was available in all cases, CT arthrography in 13 cases, and one patient underwent surgical confirmation. All patients were sent for an ultrasound for suspect lesion of the tendons of the rotator cuff, with posterior pain in the infraspinatus fossa. All cases seen on ultrasonography were confirmed on MRI. CT arthrography confirmed the absence of tear of the IS tendon in all cases and did not reveal the MTJ tears. Two signs appeared to us as being of special interest: the "tadpole sign" on longitudinal views, and the "black eye sign" on sagittal views. The proximal retraction of the tendon at the MTJ is the anatomical explanation of both signs. Tears at the myotendinous junction of the infraspinatus are rare but can be diagnosed on US examination, provided that the sonographer pays attention to the infraspinatus fossa especially in cases of normality of the distal tendinous cuff.

Effects of adding local anesthetic and iodinated contrast agents to the paramagnetic contrast solution in direct MR arthrography.

published in the present issue of Radiologia Brasi-leira. Such authors have carried out in vitro investigations of dif-ferent concentrations of diluted gadolinium-saline solution com-bined with local anesthetic (lidocaine) and iodinated contrast agent.The results of this study have potential implications for the evalu-ation of internal joint derangements using magnetic resonance ar-thrography (MRA).Iodinated contrast agent is included by some radiologists inthe composition of paramagnetic contrast-saline solution preparedfor direct MRA. Other radiologists prefer to inject iodinated con-trast into the joint prior the gadolinium injection. In both situa-tions, the iodinated contrast agent is useful to confirm the intra-articular positioning of the needle in cases where fluoroscopy isutilized to guide the procedure. With both techniques, the end resultis a mix of iodinated contrast agent and gadolinium in the intra-articular saline solution. Another advantage of using an end solu-tion with iodinated contrast agent is the possibility of converting aMRA into a computed tomography arthrography (CTA), in caseswhere the patient shows claustrophobia or in case of unexpectedtechnical problems with the MRI equipment during MRI acquisi-tion. CTA represents an interesting alternative to investigate jointdiseases when multislice CT equipment is available

Computed Tomography Arthrography Using a Radial Plane View for the Detection of Triangular Fibrocartilage Complex Foveal Tears

To classify triangular fibrocartilage complex (TFCC) foveal lesions on the basis of computed tomography (CT) arthrography using a radial plane view and to correlate the CT arthrography results with surgical findings. We also tested the interobserver and intra-observer reliability of the radial plane view. A total of 33 patients with a suspected TFCC foveal tear who had undergone wrist CT arthrography and subsequent surgical exploration were enrolled. We classified the configurations of TFCC foveal lesions into 5 types on the basis of CT arthrography with the radial plane view in which the image slices rotate clockwise centered on the ulnar styloid process. Sensitivity, specificity, and positive predictive values were calculated for each type of foveal lesion in CT arthrography to detect foveal tears. We determined interobserver and intra-observer agreements using kappa statistics. We also compared accuracies with the radial plane views with those with the coronal plane views. Among the tear types on CT arthrography, type 3, a roundish defect at the fovea, and type 4, a large defect at the overall ulnar insertion, had high specificity and positive predictive value for the detection of foveal tears. Specificity and positive predictive values were 90% and 89% for type 3 and 100% and 100% for type 4, respectively, whereas sensitivity was 35% for type 3 and 22% for type 4. Interobserver and intra-observer agreement was substantial and almost perfect, respectively. The radial plane view identified foveal lesion of each palmar and dorsal radioulnar ligament separately, but accuracy results with the radial plane views were not statistically different from those with the coronal plane views. Computed tomography arthrography with a radial plane view exhibited enhanced specificity and positive predictive value when a type 3 or 4 lesion was identified in the detection of a TFCC foveal tear compared with historical controls. Diagnostic II.