Intraarticular Contrast Material Research Articles

MRI of the Elbow - Update 2024.

Elbow pain can result in significant morbidity. MRI can help diagnosing the cause of elbow pain.Based on a systematic literature search as well as knowledge gained through frequent participation in conferences dedicated to advances in musculoskeletal imaging, this review aims to give a brief overview of normal anatomy and common pathologies of tendons and ligaments of the elbow on magnetic resonance imaging.Stabilization of the elbow joint is provided by osseous structures and passive ligamentous and active muscular support. Loss of these important stabilizers, due to trauma and overuse, can result in elbow instability. Additional MR views or intra-articular contrast media can be useful for the detection of specific pathologies.MRI is frequently used to detect posttraumatic or chronic conditions, which can lead to posterolateral or posteromedial elbow instability. Knowledge of normal anatomy, variants, pathologies, as well as appropriate imaging is crucial to make the diagnosis. · Epicondylitis occurs due to chronic degeneration with tendinosis and partial tendon tearing and is not related to an acute inflammatory reaction.. · Posterolateral or posteromedial elbow instability can be the result of trauma with loss of passive ligamentous and active muscular stabilization.. · The most common elbow instability is posterolateral rotatory instability with the LUCL being the most important stabilizer affected by injury.. · Schinnerl C, Weber M, Benninger E et al. MRI of the Elbow - Update 2024. Fortschr Röntgenstr 2024; DOI 10.1055/a-2416-1491.

Lesions of the rotator cuff and biceps tendon

The rotator cuff is acomplex anatomical structure and the integrity is pivotal for the shoulder functionality. The pathologies are often multifactorial, resulting from degenerative, vascular, traumatic and mechanical factors. Radiography, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) form the pillars of radiological diagnostics. Each modality has specific advantages and limitations in the visualization and assessment of pathologies of the rotator cuff and biceps tendon. The MR arthrography offers additional insights in unclear cases by enhancing the differentiation between complete and partial tears. The MRI provides detailed information on tendon quality and associated damages, such as muscle atrophy and fat infiltration, making it the preferred method. The use of MR arthrography can identify defects through increased intra-articular pressure or contrast medium leakage. Muscle damage, as induced by edema in acute injuries or fatty degeneration in chronic conditions, can be evaluated using imaging techniques. Special attention is warranted for the infraspinatus, subscapularis and teres minor muscles due to their unique injury patterns and prevalences.

Direct MR arthrography of the hip joint: anterior approach without imaging guidance.

The purpose of this study is to describe the anterior injection approach, with anatomical landmark guidance, for direct MR arthrography (dMRA) of the hip joint, and to evaluate the effectiveness in joint distension and the security of the technique. Retrospective review of hip dMRAs was conducted on patients with suspected intra-articular pathology from two MR outpatient centers, performed by two radiologists with 25 and 5years of experience, respectively. The analysis included assessing the presence of intra-articular contrast material (gadolinium-based solution), the number of injections performed, the degree of joint distension, and the degree of contrast extravasation. A multi-variant analysis was carried out to determine if the procedure success depend on any of the demographic variants or on the radiologist experience. Additionally, the presence of immediate and medium-term post-puncture complications was evaluated. One hundred patients with 104 hip dMRA were included; 60 were men, with mean age of 38years (16-63years). Contrast material was successfully introduced intra-articularly in 100% of patients, being necessary a second puncture only in 6% of procedures. The capsular distension was considered optimal for diagnosis in 97% of cases. Different degrees of contrast extravasation were found in 30% of dMRA. There was no statistically significant relationship observed between patient variables and the performance of dMRA, nor did it show any correlation with the experience of the radiologists. No puncture-derived complications were found. Hip dMRA through anterior injection guided by anatomical references is an effective and safe alternative for patients with suspected intra-articular pathology.

Advantages of the Use of Axial Traction Magnetic Resonance Imaging (MRI) of the Shoulder in Patients with Suspected Rota-Tor Cuff Tears: An Exploratory Pilot Study

Magnetic Resonance Imaging (MRI) with axial traction is a tool for the assessment of musculoskeletal pathology. Previous reports have demonstrated a better distribution of intra-articular contrast material. No investigations were performed to evaluate glenohumeral joint axial traction MRI in patients with suspected rotator cuff tears. This study aims to assess the morphological changes and the potential advantage of glenohumeral joint axial traction MRI without intra-articular contrast administration in patients with suspected rotator cuff tears. Eleven patients with clinical suspicion of rotator cuff tears underwent a shoulder MRI scan with and without axial traction. PD weighted images with SPAIR fat saturation technique and T1 weighted images with TSE technique were acquired in the oblique coronal, oblique sagittal and axial planes. Axial traction allowed a significant widening of the subacromial space (11.1 ± 1.5 mm vs. 11.3 ± 1.8 mm; p = 0.001) and inferior glenohumeral space (8.6 ± 3.8 mm vs. 8.9 ± 2.8 mm; p = 0.029). With axial traction, there was a significant decrease in measurements of the acromial angle (8.3 ± 10.8° vs. 6.4 ± 9.8°; p < 0.001) and gleno-acromial angle (81 ± 12.8° vs. 80.7 ± 11.5°; p = 0.020). Our investigation demonstrates for the first time significant morphological changes in the shoulder of patients with suspected rotator cuff tears who underwent a glenohumeral joint axial traction MRI.

Sacroiliac Joint Intraarticular Injection in True Anteroposterior View: Description of a New C-Arm Guided Method

The anatomic characteristics of the sacroiliac joint (SIJ) make it difficult to achieve intraarticular injection without radiologic guidance. The classic C-arm guided SIJ intervention technique is difficult. Here we describe a new and simple method for SIJ intraarticular intervention. This study aims to introduce a new, simple approach for SIJ intraarticular intervention. An observational case series study. The study was conducted at an academic medical center in a major metropolitan city. This method of intervention was performed on 57 patients (a total of 73 joints) who were selected for diagnostic and therapeutic SIJ intervention. The procedure was done in anteroposterior (AP) view, without any C-arm angulation. The accuracy of the intraarticular injection was confirmed by using intraarticular contrast material. A numerical rating scale (NRS) score was recorded for each joint before and after the procedure; the number of x-ray exposures and number of attempts were recorded for each procedure as well. Successful intraarticular contrast spread was obtained in all SIJs. The number of x-ray exposures was about 9 ± 3, and there was not a remarkable difference between cases according to gender of the patient (P = 0.1) or side of the joint (P = 0.2). In 5 cases, the first needle placement was not correct; there were no differences between gender (P = 0.4) and side of the joint (P = 0.4) regarding the first successful attempt. The NRS pain scores decreased in all of the patients more than 50% after the procedure; the pain scores were similar to the results of classic methods of intraarticular interventions with successful contrast spread, and there were no remarkable differences considering gender (P = 0.5) or side of the joint (P = 0.8). This is a very small, nonrandomized, and controlled study; further blinded clinical trials are needed to clarify the probable advantages of this method compared with conventional ones. This observational study introduces a new and simple approach for SIJ intraarticular intervention, with a high success rate. Low back pain, sacroiliac joint, C-arm, new technique, intraarticular, injection.

Diagnosis of Superior Labrum Anterior-to-Posterior Tears by Using MR Imaging and MR Arthrography: A Systematic Review and Meta-Analysis.

Purpose To evaluate the diagnostic accuracies of nonenhanced magnetic resonance (MR) imaging and MR arthrography for diagnosis of superior labrum anterior-to-posterior (SLAP) tears by using a systematic review and meta-analysis. Materials and Methods A comprehensive literature search was performed on the two main concepts of MR imaging (MR imaging, and direct and indirect MR arthrography) and SLAP tears. Inclusion criteria consisted of original studies that assessed the diagnostic accuracy of MR imaging, direct MR arthrography, and/or indirect MR arthrography for the detection of SLAP tears, by using surgical findings as the reference standard. The Quality Assessment of Diagnostic Accuracy Studies 2, or QUADAS-2 Quality Assessment of Diagnostic Accuracy Studies 2 Quality Assessment of Diagnostic Accuracy Studies 2 , tool was used to assess methodologic quality. Meta-analyses were performed that compared MR imaging studies to direct MR arthrography studies and indirect MR arthrography studies, 3-T studies to 1.5-T studies, and low-bias MR imaging studies to low-bias direct MR arthrography studies. Study variation was analyzed by using the Cochran Q test of heterogeneity and the I2 statistic. Results Thirty-two studies met inclusion and exclusion criteria, including 3524 imaging examinations: 1963 direct MR arthrography examinations (23 studies), 1402 MR examinations (14 studies), and 159 indirect MR arthrography examinations (three studies). Twelve studies had low risk for bias, two had questionable risk, and 18 had high risk. Mean sensitivities of direct MR arthrography, MR imaging, and indirect MR arthrography for SLAP tear diagnosis were 80.4%, 63.0%, and 74.2%, respectively. Mean specificities of direct MR arthrography, MR imaging, and indirect MR arthrography were 90.7%, 87.2%, and 66.5%, respectively. Summary receiver operator characteristic (ROC) curve demonstrated superior accuracy of direct MR arthrography compared with those of MR imaging and indirect MR arthrography. Similar findings were observed in the low-bias subanalysis. Summary ROC curve demonstrated overall superiority of 3-T imaging, with or without intra-articular contrast material compared with 1.5-T imaging, with or without intra-articular contrast material. Significant variance was observed for MR imaging and direct MR arthrography (P < .001) studies for both mean sensitivity and specificity. Conclusion Direct MR arthrography appears to be more accurate than nonenhanced MR imaging for diagnosis of SLAP tears, whereas 3-T MR imaging with or without intra-articular contrast material appears to improve diagnostic accuracy compared with 1.5-T MR imaging with or without intra-articular contrast material. © RSNA, 2017 Online supplemental material is available for this article.

Current knowledge and importance of dGEMRIC techniques in diagnosis of hip joint diseases.

Accurate assessment of early hip joint cartilage alterations may help optimize patient selection and follow-up of hip joint preservation surgery. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is sensitive to the glycosaminoglycan content in cartilage that is lost early in the development of osteoarthritis (OA). Hence, the dGEMRIC technique holds promise for the development of new diagnostic and therapeutic procedures. However, because of the location of the hip joint deep within the body and due to the fairly thin cartilage layers that require high spatial resolution, the diagnosis of early hip joint cartilage alterations may be problematic. The purpose of this review is to outline the current status of dGEMRIC in the assessment of hip joint cartilage. A literature search was performed with PubMed, using the terms "cartilage, osteoarthritis, hip joint, MRI, and dGEMRIC", considering all levels of studies. This review revealed that dGEMRIC can be reliably used in the evaluation of early stage cartilage pathology in various hip joint disorders. Modifications in the technique, such as the operation of three-dimensional imaging and dGEMRIC after intra-articular contrast medium administration, have expanded the range of application. Notably, the studies differ considerably in patient selection and technical prerequisites. Furthermore, there is a need for multicenter prospective studies with the required technical conditions in place to establish outcome based dGEMRIC data to obtain, in conjunction with clinical data, reliable threshold values for normal and abnormal cartilage, and for hips that may benefit from conservative or surgical treatment.

Single-row vs. double-row arthroscopic rotator cuff repair: clinical and 3 Tesla MR arthrography results

BackgroundArthroscopic rotator cuff repair has become popular in the last few years because it avoids large skin incisions and deltoid detachment and dysfunction. Earlier arthroscopic single-row (SR) repair methods achieved only partial restoration of the original footprint of the tendons of the rotator cuff, while double-row (DR) repair methods presented many biomechanical advantages and higher rates of tendon-to-bone healing. However, DR repair failed to demonstrate better clinical results than SR repair in clinical trials. MR imaging at 3 Tesla, especially with intra-articular contrast medium (MRA), showed a better diagnostic performance than 1.5 Tesla in the musculoskeletal setting. The objective of this study was to retrospectively evaluate the clinical and 3 Tesla MRA results in two groups of patients operated on for a medium-sized full-thickness rotator cuff tear with two different techniques.MethodsThe first group consisted of 20 patients operated on with the SR technique; the second group consisted of 20 patients operated on with the DR technique. All patients were evaluated at a minimum of 3 years after surgery. The primary end point was the re-tear rate at 3 Tesla MRA. The secondary end points were the Constant-Murley Scale (CMS), the Simple Shoulder Test (SST) scores, surgical time and implant expense.ResultsThe mean follow-up was 40 months in the SR group and 38.9 months in the DR group. The mean postoperative CMS was 70 in the SR group and 68 in the DR group. The mean SST score was 9.4 in the SR group and 10.1 in the DR group. The re-tear rate was 60% in the SR group and 25% in the DR group. Leakage of the contrast medium was observed in all patients.ConclusionsTo the best of our knowledge, this is the first report on 3 Tesla MRA in the evaluation of two different techniques of rotator cuff repair. DR repair resulted in a statistically significant lower re-tear rate, with longer surgical time and higher implant expense, despite no difference in clinical outcomes. We think that leakage of the contrast medium is due to an incomplete tendon-to-bone sealing, which is not a re-tear. This phenomenon could have important medicolegal implications.Level of evidence III. Treatment study: Case–control study.

Paralabral cysts in the hip joint: findings at MR arthrography

The purpose of this research was to retrospectively characterize paralabral cysts of the hip as seen at MR arthrography. After Institutional Review Board approval, 704 patients who had MR arthrography were identified over a 3-year period and 40 patients were identified as having a cyst or fluid collection at the hip by MR report. MR images from these 40 patients were retrospectively reviewed by three radiologists where 18 were found to have a paralabral cyst, which were characterized as follows: location, configuration, contrast filling, size of the cyst, extent, direction, and whether associated osseous changes were present. In addition, the acetabular labrum was assessed for tears and, if present, the location and pattern were characterized. Paralabral cysts were located anterosuperiorly in 56%, anteriorly in 22%, posterosuperiorly in 17%, and anteroinferiorly in 6% of cases. The vast majority (94%) were multilocular and filled with intra-articular contrast medium. The average dimensions were 8 × 7 × 11 mm. The paralabral cyst demonstrated extracapsular extension in 72% of cases, with 39% located between the ilium and gluteus minimus, and 22% between the ilium and iliopsoas. Remodeling of the ilium adjacent to the cyst was observed in 50% of these cases. A labral tear was at the base of the labrum adjacent to the cyst in 78% of cases, while the tear was isolated to the body of the labrum in 22%. Tears were most commonly anterosuperior (55%) or anterior (28%) in location. Our results show that paralabral cysts of the hip are most commonly located anterosuperiorly, are multilocular, fill with intra-articular contrast medium, have average dimensions up to 11 mm, and often extend extracapsularly between muscle and bone where they may remodel the adjacent ilium.

Intraosseous Ganglion With Impending Fracture of the Glenoid

Intraosseous ganglia are benign cystic and often multiloculated lesions located in the subchondral bone. Only 13 cases around the shoulder have been described in the literature. These lesions are often asymptomatic, but, in cases located close to neurovascular structures or articular surfaces, they can be symptomatic, causing pain, neurologic dysfunction, or articular fractures. This article reports the clinical, radiographic, and pathological findings of a 34-year-old man reporting shoulder pain during heavy working activities. At physical examination, his left shoulder showed complete active and passive range of motion but was painful in external rotation and extension. Tests for the evaluation of the rotator cuff were all negative. The anterior apprehension test provoked pain. The Constant-Murley score was 59 points. Radiographs, computed tomography (CT) scan, and magnetic resonance arthrography showed an elliptical-shaped osteolytic area in the anteroinferior portion of the glenoid extending to the anteroinferior glenoid margin. Leakage of the intra-articular contrast medium showed that the cyst had eroded the articular surface and was about to cause an intra-articular fracture of the glenoid. The patient was operated on with the suspicion of an intraosseous ganglion. The cyst was curetted carefully and packed with autologous bone from the proximal tibia and artificial bone chips. At 1-year follow-up, the patient was completely asymptomatic and reported no pain during his working activities. Physical examination was negative. Radiographs and CT scan showed a cystic lesion in the anteroinferior margin of the glenoid that was partially filled by bone.

Fluid Extravasation during Hip Arthroscopy

The amount of fluid that may be lost into the soft tissues during hip arthroscopic surgery is unknown. We measured the volumes of irrigation fluid infused, operating time, fluid pressures and volumes of fluid recovered in 36 therapeutic hip arthroscopies. We excluded those where fluid was lost to the floor, leaving 28 patients. The majority were undergoing surgery for the treatment of femoroacetabular impingement. In 5 patients an intra-articular contrast medium was instilled, in order to establish the likely location of any extravasated fluid. The mean operating time was 68 minutes (31 to 120), and the mean infusion pressure was 46 mm Hg (30 to 70). The mean volume of infused fluid was 9677 ml (95% confidence interval (CI) 7715 to 11638) and the mean volume of fluid recovered was 8544 ml (95% CI 6715 to 10373). The mean fluid extravasation loss into the peri-articular tissues was 1132 ml (95% CI 808 ml to 1456 ml). There was a significant correlation between the volume of extravasated fluid and both the length of operation and the volume of infused fluid used. We had no adverse events in our series. During arthroscopic hip surgery more than a litre of irrigation fluid may be extravasated into the soft tissues. In order to reduce problems related to this we attempt to keep operating times low, and maintain intra-operative fluid pressures as low as possible.

Comparison of cross-sectional anatomy and computed tomography of the tarsus in horses

To compare computed tomography (CT) images of equine tarsi with cross-sectional anatomic slices and evaluate the potential of CT for imaging pathological tarsal changes in horses. 6 anatomically normal equine cadaveric hind limbs and 4 tarsi with pathological changes. Precontrast CT was performed on 3 equine tarsi; sagittal and dorsal reconstructions were made. In all limbs, postcontrast CT was performed after intra-articular contrast medium injection of the tarsocrural, centrodistal, and tarsometatarsal joints. Images were matched with corresponding anatomic slices. Four tarsi with pathological changes underwent CT examination. The tibia, talus, calcaneus, and central, fused first and second, third, and fourth tarsal bones were clearly visualized as well as the long digital extensor, superficial digital flexor, lateral digital flexor (with tarsal flexor retinaculum), gastrocnemius, peroneus tertius, and tibialis cranialis tendons and the long plantar ligament. The lateral digital extensor, medial digital flexor, split peroneus tertius, and tibialis cranialis tendons and collateral ligaments could be located but not always clearly identified. Some small tarsal ligaments were identifiable, including plantar, medial, interosseus, and lateral talocalcaneal ligaments; interosseus talocentral, centrodistal, and tarsometatarsal ligaments; proximal and distal plantar ligaments; and talometatarsal ligament. Parts of the articular cartilage could be assessed on postcontrast images. Lesions were detected in the 4 tarsi with pathological changes. CT of the tarsus is recommended when radiography and ultrasonography are inconclusive and during preoperative planning for treatment of complex fractures. Images from this study can serve as a CT reference, and CT of pathological changes was useful.

Evaluation of the Glenoid Labrum With 3-T MRI: Is Intraarticular Contrast Necessary?

The purpose of this study was to evaluate the diagnostic accuracy of 3-T MRI versus 3-T MR arthrography for assessing labral abnormalities in the shoulder using arthroscopy as the gold standard. Forty-two patients (28 men, 14 women; mean age, 33 years) underwent MR arthrography and conventional MRI of the same shoulder. Two patients underwent bilateral shoulder examinations, for a total of 44 shoulder examinations. Twenty-two shoulders underwent arthroscopy. The results of arthroscopy were used as the reference standard. Three musculoskeletal radiologists prospectively and independently interpreted MRI and MR arthrography examinations. Differences in performance of conventional MRI and MR arthrography were analyzed for statistical significance by the two-tailed McNemar test. Of the 22 arthroscopies performed, 26 labral tears were found in 18 shoulders and four shoulders were normal with respect to the labrum. There were 12 superior, nine posterior, and five anterior labral tears identified at arthroscopy. By consensus review, conventional MRI identified nine of 12 superior (sensitivity, 75%; specificity, 100%), seven of nine posterior (sensitivity, 78%; specificity, 92%), and three of five anterior (sensitivity, 60%; specificity, 94%) labral tears. MR arthrography identified nine of 12 superior (sensitivity, 75%; specificity, 100%), eight of nine posterior (sensitivity, 89%; specificity, 100%), and five of five anterior (sensitivity, 100%; specificity, 100%) labral tears. Although the power of our preliminary study is small, the results suggest that intraarticular contrast material is helpful in diagnosing labral tears in the shoulder, particularly tears of the anterior labrum. Our preliminary results suggest that MR arthrography adds value for diagnosing labral tears in the shoulder compared with conventional MRI even at 3 T.

SPECT/CT arthrography of the wrist in ulnocarpal impaction syndrome

Ulnar-sided wrist pain is a diagnostic challenge for hand surgeons and radiologists due to the complex anatomy of the involved small structures. Along with the clinical history and physical examination, imaging is important in the evaluation of ulnar-sided wrist pain [1–4]. Ulnocarpal impaction syndrome can lead to severe damage to the cartilage, triangular fibrocartilagecomplex (TFCC) and bone. The new generation of SPECT/CT devices allow SPECT and high-resolution CT imaging of the wrist with a spatial resolution of 0.33 mm in one imaging step [5]. CT arthrography of the wrist is a wellestablished investigation [6]. Combining wrist arthrography (arrowheads intraarticular contrast medium) and SPECT/CT (Arthro-SPECT/CT) offers a one-stop shop imaging approach for patients with ulnocarpal impaction. In our 63-year-old male patient with ulnar-sided wrist pain for 3 months, Arthro-SPECT/CT demonstrated severe osteoarthritis of the distal radioulnar joint (DRUJ), profound damage to the cartilage of the ulnotriquetral joint (short arrow) and a large defect in the central part of the TFCC (short arrow). Concomitant increased uptake was observed in the triquetral bone (long arrow )a nd DRUJ. Arthro-SPECT/CT of the wrist is feasible and offers unique anatomic and metabolic information to the hand surgeon in patients with ulnar-sided wrist pain. Arthro-SPECT/CTseems to be a promising alternative to wrist MRI. Conflicts of interest None.

Efficacy of diagnostic magnetic resonance imaging for articular cartilage lesions of the glenohumeral joint in patients with instability

The purpose of this study was primarily to assess the diagnostic performance of magnetic resonance imaging (MRI) in detecting articular cartilage injuries in patients with glenohumeral instability. A secondary purpose was to assess the diagnostic performance of MRI for detection of Hill-Sachs and Bankart lesions. A cohort of 87 consecutive patients who underwent diagnostic MRI and shoulder arthroscopy for instability from 1997 to 2006 were identified. Fifty-five patients (63.2%) underwent MRI with intra-articular contrast medium and 32 patients (36.8%) underwent MRI without contrast medium. MR images were reviewed by two radiologists and interpreted by consensus for the presence of articular cartilage lesions (including Hill-Sachs and Bankart lesions), which were then confirmed by reviewing the operative report and images recorded at arthroscopy. Mean patient age was 27.0 ± 10.2 years with a mean clinical and radiographic follow-up of 29 (range 3-72) months. Cartilage injuries were detected arthroscopically in 55 patients (63%). Bankart and Hill-Sachs lesions were identified arthroscopically in 66 patients (75.9%) and 55 patients (63.2%) respectively. The overall sensitivity and specificity for detection of glenohumeral articular cartilage lesions by MRI were 87.2% and 80.6% respectively. The sensitivity and specificity of MRI in detecting Bankart lesions was 98.4% (95% CI 91.9, 99.7) and 95.2% (95% CI 77.3, 99.2) respectively. The sensitivity and specificity of MRI in detecting Hill-Sachs lesions was 96.3% (95% CI 87.6, 98.9%) and 90.6% (95% CI 75.7, 96.9) respectively. No statistically significant difference was found between MRI examinations with and without intra-articular gadolinium (p = 0.89). Magnetic resonance imaging demonstrates high sensitivity and specificity for the diagnosis of articular cartilage injuries in patients with glenohumeral instability. MRI with or without intra-articular contrast medium in this study were equally reliable as a non-invasive method for assessment of articular cartilage damage of the glenohumeral joint prior to diagnostic arthroscopy.

Annular Ligament of the Elbow: MR Arthrography Appearance With Anatomic and Histologic Correlation

As part of the lateral ligament complex of the elbow, the annular ligament has an adjunctive role in stabilizing the proximal radioulnar joint. Knowledge of the anatomy of this ligament may enhance our understanding of its functional role in maintaining integrity of the elbow joint in fracture and dislocation. The purpose of this study is to provide a detailed analysis of the anatomy of the annular ligament using MR arthrography with anatomic and histologic correlation in cadavers. MR arthrography of six fresh cadaveric elbows using coronal, axial, and sagittal planes was performed after injection of intraarticular contrast material. The MR arthrography appearance of the annular ligament was correlated with anatomic sectioning and histologic analysis. On MR arthrography, the axial and sagittal planes provided the best evaluation of the annular ligament. Although the anterior attachment of annular ligament was a single band, the posterior attachment was fenestrated in two of six specimens. Anatomic inspection confirmed the MR observations. On histology, the annular ligament appeared to be part of a complex supporting structure continuous with the elbow joint capsule, adjacent ligaments, and muscles. The annular ligament is a complex structure formed from the capsule, lateral collateral ligamentous complex, and supinator muscle that act in unison to stabilize the proximal radioulnar joint. Its posterior attachment to the ulna can be fenestrated normally. A detailed analysis of anatomy of this ligament allows us to better understand its functional role in fractures and dislocations of the elbow joint.

EFFECT OF POSITIONING, SCAN PLANE, AND ARTHROGRAPHY ON VISIBILITY OF PERIARTICULAR CANINE SHOULDER SOFT TISSUE STRUCTURES ON MAGNETIC RESONANCE IMAGES

This study was performed to determine the effect of shoulder extension and flexion, imaging plane, and intraarticular paramagnetic contrast medium administration on the visibility of soft tissue structures surrounding the canine shoulder joint using magnetic resonance (MR) imaging. Eight dogs without shoulder disease were imaged using a 1.5 T MR scanner. In all dogs, T1- and T2-weighted spin-echo sequences in sagittal, transverse, and dorsal planes, and a sagittal short tau inversion recovery (STIR) sequence were acquired with the shoulder joint in extension. In five dogs, postintravenous contrast medium T1-weighted images were obtained and in five dogs, MR arthrography was performed in flexion and extension. Each specific soft tissue structure was assigned a visual assessment score of 0-3 and descriptive statistics were calculated. The biceps brachii, supraspinatus, and teres minor muscles and tendons, and the biceps tendon sheath were best seen in the sagittal and transverse planes. The infraspinatus was well-visualized in all planes, the subscapularis was best seen in the transverse and dorsal planes, and the capsuloligmentous complexes were best seen in the transverse and dorsal planes. Limb extension improved conspicuousness of the medial capsuloligamentous stuctures. Arthrography resulted in greater conspicuousness of the biceps brachii tendon, biceps tendon sheath, infraspinatus, supraspinatus, subscapularis, medial joint capsule, medial glenohumeral ligament, and the lateral joint capsule-glenohumeral ligament complex. The major periarticular anatomic structures of the normal canine shoulder were consistently identified using the protocols described in this investigation, but arthrography with the joint in extension resulted in the best visualization of all structures.

Retears of postoperative knee meniscus: findings on magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) by using low and high field magnets

The purpose of this study was to determine the diagnostic performance of magnetic resonance (MR) obtained with intra-articular contrast medium in the evaluation of recurrent meniscal tears using low-field extremity-only and high-field whole-body magnets. Postoperative standard MR examinations and MR arthrographies of 95 knees were reviewed. Patients experiencing pain and disability after meniscal repair underwent standard MR and MR arthrography (Gadoterate meglumine 0.0025 mmol/ml) on both a 0.2-T and 1.5-T magnet. In 52 of 95 patients, second-look arthroscopy was performed; in the remaining 43 of 95 patients, clinical follow-up was used as the standard of reference. Sensitivity, specificity, positive and negative predictive values as well as accuracy of MRI/MR arthrographic signs as meniscal morphologic changes and the presence of contrast medium tracking into the tear at T1- and T2-weighted sequences in the detection of recurrent meniscal tears were determined. All MR and MR arthrograpic signs were sensitive in the detection of recurrent tears (range 80-91%). Abnormal meniscal morphology had low specificity [26% (13/50)] for both the 0.2-T and 1.5-T scanner, whereas accuracy was 55% (52/95) and 57% (54/95), respectively. The presence of contrast medium within the meniscus substance on T2-weighted images had higher value of specificity [84% (42/50)] and accuracy [84% (80/95)] by using low field strength magnet than by using high field strength magnet [74% (37/50) and 81% (77/95), respectively]. Whereas, the increased intrameniscal signal intensity extending to the meniscal surface at T1-weighted sequences after intra-articular contrast medium administration had lower specificity and accuracy on 0.2-T images [84% (42/50) and 82% (78/95), respectively] than on 1.5-T images [90% (45/50) and 88% (84/95), respectively]. A diagnosis of recurrent meniscal tear in a previously arthroscopically repaired meniscus can be made both on 0.2-T and 1.5-T magnets on the basis of increased signal on T2-weighted and T1-weighted images in the presence of intra-articular contrast material.

Evaluation of postoperative menisci with MR arthrography and routine conventional MRI

The diagnosis of a recurrent tear can be more difficult in the postoperative meniscus. The purpose of our study was to determine the accuracy of conventional magnetic resonance imaging (MRI) and MRI with intraarticular contrast material [magnetic resonance (MR) arthrography] for detecting recurrent meniscal tears after surgery. Seventy-two patients who had arthroscopic surgery for meniscal tear and still got complaints were selected prospectively for MR arthrography and conventional MRI. Routine knee protocols with appropriate surface coil were used on 0.5 T MRI system. A 1:100 gadolinium-saline solution 30-40 ml was injected intraarticulary for MR arthrography. Of 72 patients, 45 had repeated arthroscopy for comparison of the results. The morphology of the meniscus as seen on MR images was characterized according to meniscal repair an the degree of meniscal resection into three groups. (1) less than 25% of the meniscal resection, (2) more than 25% meniscal resection, (3) meniscal repair. With routine conventional MR images, we grouped patients according to the signal intensity of menisci as Grade 1, Grade 2, Grade 3, and tear. The prevalence of recurrent meniscal tears in our study group was [68% (37/72 tears)]. In the diagnosis of recurrent meniscal tear, conventional MRI and MR arthrography had sensitivities of 54.0% and 94.5%, respectively; specificities of 75.0% and 87.5%, respectively; and accuracy of 57.7% and 93.4%, respectively. The accuracy of the conventional MRI studies was significantly less than that of the MR arthrography group (P<.05). Our study results indicate high overall accuracy for MR arthrography in the diagnosis of recurrent or residual meniscal tears. When meniscal resection is minimal, the right diagnosis could be obtained with conventional MRI. MR arthrography is necessary for patients with meniscal resection of more than 25% and who do not have sufficient joint effusion.

Postoperative Evaluation of the Knee after Autologous Chondrocyte Implantation: What Radiologists Need to Know

Articular cartilage lesions occur commonly. Cartilage is relatively avascular and is unable to self-repair. A chondral lesion may become symptomatic. It may lead to osteoarthritis and increased morbidity. The aim of cartilage repair is to restore hyaline cartilage. There are many types of cartilage repair surgery, most of which result in fibrocartilage repair tissue that is suboptimal. Autologous chondrocyte implantation has been shown to produce hyaline-type repair tissue. Magnetic resonance (MR) imaging is performed preoperatively to define the ulcer and postoperatively to evaluate the technical success of implantation and the state of cartilage healing and to identify potential complications. Features of the autologous chondrocyte implantation graft that are assessed include the degree of filling by repair tissue, its integration with native cartilage and subchondral bone, the character of the graft substance and surface, and the underlying bone. MR arthrography is superior to unenhanced MR imaging because intraarticular contrast material allows the recipient site to be physically separated from adjacent structures so that it can be characterized more accurately. MR imaging and arthroscopy are complementary investigations in the follow-up of an autologous chondrocyte implantation in the knee. The appearance of the knee after autologous chondrocyte implantation varies among individuals and according to the time-course of healing. Familiarity with the surgical procedure and imaging appearance is essential for an accurate postsurgical assessment.