Techniques for MR imaging of joints in sports medicine.

Technical advances in MR imaging of sports-related bone and joint derangement have improved our ability to evaluate these problems. This article discusses current utilization of MR imaging, advances in local coils, pulse sequences and parameters, and reviews current aspects and indications for MR arthrography.

Comparison of fat-saturation fast spin echo versus conventional spin-echo MRI in the detection of rotator cuff pathology.

The purpose of this study was to compare the diagnostic performance of fat-saturation fast-spin-echo (FSE) T2-weighted (T2W) sequences with conventional spin-echo (CSE) T2W sequences in the detection of rotator cuff pathology using surgery as the reference standard. Oblique coronal dual-echo CSE and FSE T2W images with fat saturation from 50 surgically confirmed MR shoulder examinations were acquired on a 1.5-T MR scanner. Blinded MR readers retrospectively analyzed each imaging sequence separately and ultimately correlated both sequences together with findings at surgery. FSE was 100% sensitive and 94% specific in detection of full-thickness tears (n = 19) and 73% sensitive and 97% specific in the detection of partial-thickness rotator cuff tears (n = 13). There was no statistically significant difference in the performance of FSE with fat saturation compared with CSE. The two discrepancies between imaging sequences related to the extent of partial-thickness tears. Our findings suggest that fat-saturation FSE imaging can effectively replace CSE imaging in the evaluation of rotator cuff pathology.

Synovial chondromatosis of the distal radioulnar joint: a case report.

The most definitive method for confirming the diagnosis of synovial chondromatosis is the identification of cartilaginous metaplasia within the synovium on histologic examination. In advanced stages of the disease, plain radiographs and magnetic resonance imaging (MRI) scans demonstrate calcified and cartilaginous bodies, respectively, but in earlier stages, plain radiographic findings may be normal and MRI scans may reveal only nonspecific increased fluid. Although rare in the wrist, synovial chondromatosis must be considered in the differential diagnosis in a patient presenting with pain and swelling of the distal radioulnar joint. Surgical exploration of the joint and synovectomy, alone or in combination with removal of loose bodies, is the recommended treatment.

MR imaging of the rotator cuff: peritendinous and bone abnormalities in an asymptomatic population.

OBJECTIVE: MR imaging of the shoulder was performed in an asymptomatic population to determine the prevalence of MR-evident peritendinous and bone abnormalities. Findings were correlated with subject age and rotator cuff abnormalities. SUBJECTS AND METHODS: Dual-echo T2-weighted oblique coronal MR images of the shoulder were evaluated for 100 asymptomatic volunteers who were 19-88 years old. Twenty symptomatic patients with arthroscopic correlation were included as controls. Images were assessed independently by two reviewers with no knowledge of subject history or symptomatology. Bursal, peribursal, and bone findings were correlated with subject age and the appearance of the rotator cuff tendon. RESULTS: Changes characteristic of acromioclavicular joint osteoarthrosis were present in three fourths of the shoulders. One third had subacromial spurs. Changes in the peribursal fat plane and the presence of fluid in the subacromial-subdeltoid bursa paralleled the degree of MR-evident rotator cuff abnormalities. Joint fluid was observed in nearly all subjects. CONCLUSION: Our findings reveal a high prevalence of MR-evident bone and peritendinous shoulder abnormalities among asymptomatic individuals. The prevalence of subacromial spurs and humeral head cysts correlated closely with the severity of MR-evident rotator cuff abnormalities, as did changes in the bursa and peribursal fat. Acromioclavicular joint osteoarthrosis is seen in many shoulders independently of rotator cuff disease; therefore, its presence alone does not appear to be a reliable indicator of pain or tendon disease.

Abnormal findings on magnetic resonance images of asymptomatic shoulders.

Magnetic resonance images of the shoulders of ninety-six asymptomatic individuals were evaluated to determine the prevalence of findings consistent with a tear of the rotator cuff. The scans were reviewed independently by two diagnostic radiologists who are experienced in the interpretation of magnetic resonance images of the shoulder. The over-all prevalence of tears of the rotator cuff in all age-groups was 34 per cent (thirty-three). There were fourteen full-thickness tears (15 per cent) and nineteen partial-thickness tears (20 per cent). The frequency of full-thickness and partial-thickness tears increased significantly with age (p < 0.001 and 0.05, respectively). Twenty-five (54 per cent) of the forty-six individuals who were more than sixty years old had a tear of the rotator cuff: thirteen (28 per cent) had a full-thickness tear and twelve (26 per cent) had a partial-thickness tear. Of the twenty-five individuals who were forty to sixty years old, one (4 per cent) had a full-thickness tear and six (24 per cent) had a partial-thickness tear. Of the twenty-five individuals who were nineteen to thirty-nine years old, none had a full-thickness tear and one (4 per cent) had a partial-thickness tear. Magnetic resonance imaging identified a high prevalence of tears of the rotator cuff in asymptomatic individuals. These tears were increasingly frequent with advancing age and were compatible with normal, painless, functional activity. The results of the present study emphasize the potential hazards of the use of magnetic resonance imaging scans alone as a basis for the determination of operative intervention in the absence of associated clinical findings.

Rupture of the distal biceps tendon: evaluation with MR imaging.

PURPOSE: To assess the usefulness of magnetic resonance (MR) imaging in the diagnosis of distal biceps tendon ruptures. MATERIALS AND METHODS: MR images of the elbow in 20 patients with suspected distal biceps injury were retrospectively reviewed along with those of eight asymptomatic volunteers. Surgical confirmation was obtained in nine cases. RESULTS: MR imaging helped diagnose 10 complete ruptures with depiction of the absence of the tendon distally (n = 10), a fluid-filled tendon sheath (n = 9), an antecubital fossa mass (n = 3), muscle edema (n = 3), and atrophy (n = 2). Six partial tears were depicted with high signal intensity within the tendon (n = 6), fluid in the biceps tendon sheath (n = 6), and thinning (n = 3) or thickening (n = 3) of the distal tendon. Of the remaining patients, one each had tendinosis, tenosynovitis, a biceps hematoma, and a brachialis contusion. CONCLUSION: MR imaging helped confirm distal biceps tendon ruptures because it distinguished complete from partial ruptures and other entities that may mimic ruptures.

Magnetic resonance pathology of the rotator cuff.

This article reviews the current issues in imaging of the rotator cuff with magnetic resonance imaging (MRI). Important technical issues are discussed, including some of the newer pulse sequences, surface coils, and MR arthrography. Debate continues over what constitutes the normal appearance of the rotator cuff. Issues regarding studies of asymptomatic volunteers, pitfalls in imaging, and MR artifacts such as magic angle effects are discussed. The article also reviews the basic concepts of MR interpretation of pathologic lesions of the cuff, including tendinopathy, partial and complete tears, and the relationships to rotator cuff impingement.

Posttraumatic changes in the posterior glenoid and labrum in a handball player.

Magnetic resonance imaging evaluation of a handball player with chronic pain in his nondominant shoulder revealed posttraumatic changes in the posterior glenoid and labrum. This provided a pathophysiologic explanation for the patient's symptoms.

Iliotibial band friction syndrome: MR imaging findings.

Six patients with clinical histories and physical examination results consistent with iliotibial band friction syndrome (ITBFS) were examined with magnetic resonance (MR) imaging. Ill-defined decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images was present deep to the iliotibial band, adjacent to the lateral femoral epicondyle. Axial fast imaging with steady-state precession (FISP) gradient-echo sequences were essential in differentiating the ill-defined signal intensity abnormality associated with ITBFS from fluid in the lateral knee joint. None of these patients were found to have lateral meniscal tears, and all responded to conservative measures directed at treating ITBFS. The authors conclude that MR imaging may be useful in confirming or establishing the diagnosis of ITBFS in patients with the appropriate clinical history and distal lateral thigh or lateral knee pain.

Magnetic resonance imaging of the wrist.

Magnetic resonance (MR) imaging has developed rapidly as a diagnostic tool in the evaluation of the wrist. In this article, the authors review simple high-resolution technique and appropriate surface coils to aid in wrist evaluation. Evaluation of the wrist is facilitated by an understanding of the anatomy of the carpal ligaments, the triangular fibrocartilage, and the carpal tunnel, and the anatomic features of the distal radioulnar joint. Triangular fibrocartilage tears, which represent an important cause of ulnar wrist pain, are well evaluated on MR. These appear as a linear band of increased signal on the short repetition time/echo time (TR/TE), proton density weighted spin echo, or gradient echo images. True tears should be differentiated from degenerative changes, which do not demonstrate increase in signal on T2 or T2* weighted images. With good technique, accuracies approaching 90% have been reported. MR is also useful in evaluating injuries of the interosseous ligaments and volar and dorsal radiocarpal ligaments and distal radioulnar joint instability. MR also has a role in evaluating the carpal tunnel syndrome. This is especially true with patients for whom symptoms suggest the diagnosis of carpal tunnel syndrome but for whom few objective findings exist. Findings suggestive of carpal tunnel syndrome include diffuse swelling of the median nerve, flattening of the median nerve at the level of the hamate, and increased signal of the median nerve on the long TR/TE images. MR is also indicated in avascular necrosis of the carpal bones and occult carpal fractures. MR is useful in evaluating bone tumors, particularly with regard to their extent. With the advent of more rapid scanning techniques, kinematic studies are feasible. For these, fast gradient echo techniques are employed and serial images are acquired during radial and ulnar deviation. These images may be helpful in observing integrity of intercarpal ligaments and evaluating dynamic instability. With proper attention to technique, and an understanding of wrist pathophysiology, MR is a valuable diagnostic tool.

In vivo and ex vivo magnetic resonance imaging evaluation of early disc degeneration with histopathologic correlation.

The in vivo and ex vivo microanatomic appearance of early disc degeneration were identified by magnetic resonance imaging and correlated with their respective histopathologic findings. Five cadaver spines (18 discs) and 25 patient studies (122 discs) all imaged at 1.5 Tesla were studied. Two signs of early degenerative disc disease were found: infolding and the central dot. Infolding of the central fibers of the outer annulus coalesced into a central dot of low signal intensity that was seen on both the ex vivo and in vivo images. Infolding was seen 29 of 122 times, and the central dot was observed 15 to 122 times on the in vivo images. A later form of degenerative disc disease was identified as a separation of the nucleus pulposus from the hyaline cartilage end-plate. This separation was seen as a linear area of either low or high signal intensity on the ex vivo images but only as a band of high signal intensity on the in vivo spin-echo 2,500-msec/80-msec images. Only 7 of 122 in vivo discs showed this separation. Internal herniation of nucleus pulposus into the outer annulus was seen only on the ex vivo images. Early degenerative disc disease may exist before there is loss of disc height or signal intensity on the long time-to-repetition (TR)/time-to-echo (TE) magnetic resonance images.

Integrated magnetic resonance imaging and phosphorus spectroscopy of soft tissue tumors.

Eighteen patients with soft tissue masses underwent integrated magnetic resonance imaging (MRI) and phosphorus spectroscopy (31P-MRS) to evaluate benign and malignant tumor morphology and metabolism. Spectra from soft tissue tumors had a significantly higher proportion of phosphate in the low-energy portion of the 31P spectrum (P less than 0.001) with a concomitant decrease in phosphocreatine (P less than 0.01) compared with 31P spectra from normal muscle. Malignant tumors had a mean pH of 7.35 +/- 0.13 which was greater than that of muscle tissue with a mean pH of 7.08 +/- 0.07 (P less than 0.001). All tumors had greater relative levels of phosphomonoesters, inorganic phosphate, and phosphodiesters compared with those in muscle tissue but considerable variability among tumors was noted due to tumor size, extent of tumor necrosis, and muscle contamination. Integrated MRI/MRS studies are necessary to provide exact localization of the tumor and a more correct interpretation of the 31P-MRS data.

Magnetic resonance imaging of the shoulder. Sensitivity, specificity, and predictive value.

The sensitivity, specificity, and predictive value of magnetic resonance imaging in the diagnosis of lesions of the rotator cuff, glenohumeral capsule, and glenoid labrum were evaluated in ninety-one patients and fifteen asymptomatic volunteers. Magnetic resonance imaging demonstrated 100 per cent sensitivity and 95 per cent specificity in the diagnosis of complete tears, and it consistently predicted the size of the tear of the rotator cuff. There was a definite correlation between atrophy of the supraspinatus muscle and the size of a complete, chronic tear of the rotator cuff. The sensitivity and specificity of magnetic resonance imaging in the differentiation of tendinitis from degeneration of the cuff were 82 and 85 per cent, and in the differentiation of a normal tendon from one affected by tendinitis with signs of impingement the sensitivity and specificity were 93 and 87 per cent. The formation of spurs around the acromion and acromiocalvicular joint correlated highly with increased age of the patient and with chronic disease of the rotator cuff. The sensitivity and specificity of magnetic resonance imaging in the diagnosis of labral tears associated with glenohumeral instability were 88 and 93 per cent. The study showed that high-resolution magnetic-resonance imaging is an excellent non-invasive tool in the diagnosis of lesions of the rotator cuff and glenohumeral instability.

Fluid-fluid level: a nonspecific finding in tumors of bone and soft tissue.

Fluid-fluid levels have commonly been reported to occur in aneurysmal bone cysts but have also been seen in telangiectatic osteosarcoma, chondroblastoma, and giant cell tumor of bone. The authors reviewed their experience with nine bone and three soft-tissue tumors that showed fluid-fluid levels on computed tomographic or magnetic resonance images. The bone tumors included fibrous dysplasia, simple bone cyst, recurrent malignant fibrous histiocytoma of bone, two classical osteosarcomas, and four aneurysmal bone cysts. The soft-tissue tumors included soft-tissue hemangioma and two synovial sarcomas. Except for aneurysmal bone cysts, these types of tumors have not been reported to be associated with fluid-fluid levels. Radiologic-pathologic correlation was available in seven patients; in all seven, the fluid-fluid levels indicated prior hemorrhage. The authors conclude that the presence of fluid-fluid levels in bone or soft-tissue tumors cannot be considered diagnostic of any particular tumor.

Magnetic resonance imaging of the shoulder.

Magnetic resonance imaging is rapidly becoming the procedure of choice to evaluate the shoulder. This article reviews the relevant technical, anatomic, and pathologic features important in imaging the joint with magnetic resonance, with an emphasis on rotator cuff disease and shoulder instability.

The use of magnetic resonance imaging in the evaluation of bone and soft-tissue tumors.

We believe that MR imaging should follow plain films in the imaging analysis of soft-tissue tumors and bone tumors suspected of malignancy. MR imaging is primarily useful in tumor staging, although it may aid in diagnosis and the detection of recurrent or residual disease. Gd-DTPA and MR spectroscopy are currently being evaluated in many medical centers; their utility in the work-up and management of tumors of bone and soft tissue has yet to be determined.

Combined MR imaging and spectroscopy of bone and soft tissue tumors.

Twenty-three patients with bone and soft tissue tumors were studied with combined magnetic resonance (MR) imaging and spectroscopy. The MR examinations were utilized to determine the size, internal characteristics, and relationships of the tumor to the surrounding tissues. They also determined the optimal placement of the surface coil. The surface coil profile was the localization technique utilized. Four patients were also studied with one-dimensional chemical shift localization. Tumors were grouped according to histologic type, degree of muscle contamination, size, and extent of necrosis. Quantitative comparison among the groups was carried out by comparing the mean ratios of the low-energy phosphate portion of the spectra [phosphomonoester (PME), Pi, phosphodiester (PDE)] to beta-nucleotide triphosphate (NTP). Tumor spectra typically showed a relative elevation in PME, Pi, and PDE and a relative decrease in phosphocreatinine. No characteristic spectra were observed for individual tumor types. Contamination of the tumor spectra from surrounding muscle impaired interpretation of the spectral data. Tumor size and extent of necrosis were important determinants of the relative degree of abnormally elevated metabolite peaks (PME, Pi, PDE). A trend toward a higher mean PME/beta-NTP ratio was observed among high-grade lesions. Combined MR imaging and spectroscopy is a useful way to study tumor metabolism. Muscle contamination is a significant problem in analysis of the spectra. Better localization techniques are required.

Magnetic resonance imaging and magnetic resonance spectroscopy of bone tumors and bone marrow disease.

The authors have made use of an integrated magnetic resonance imaging/spectroscopy (MRI/MRS) examination to study seven patients with a variety of bone tumors. The spatial localization method used in the 31P portion of the examination was surface coil localization and a one-dimensional chemical shift imaging method (3 cases). The authors found that the precision of spatial localization was critical in many of these cases, since most of these bone tumors were surrounded by muscle tissue that contained high concentrations of phosphocreatine (PCr). For this reason, they suggest that the metabolite ratios should be referenced to the adenosine triphosphate (beta-NTP) resonance rather than PCr. The phosphate monoester (PME) to beta-NTP ratio was elevated as compared with normal muscle in all of the bone tumors studied. The authors found that all of these tumors exhibited pHs between 7.0 and 7.2, which are similar to the values found for normal muscle. They also show the feasibility of using a line-selective proton chemical shift imaging sequence with high spatial resolution for investigating changes in the fatty composition of bone marrow. This method is illustrated in an example of a patient with advanced avascular necrosis in the femoral heads.

Chronic wrist pain: evaluation with high-resolution MR imaging.

The diagnostic performance of magnetic resonance (MR) imaging in the evaluation of the triangular fibrocartilage complex and the intrinsic and extrinsic ligaments of the wrist was assessed in 43 patients with chronic wrist pain. Forty-one patients underwent correlative arthrography. Twenty-three patients underwent arthroscopy or arthrotomy or both. The normal anatomy of the triangular fibrocartilage and the intrinsic and extrinsic ligaments could be demonstrated effectively with MR imaging. MR imaging was effective in the evaluation of triangular fibrocartilage tears with a sensitivity of 1.0, a specificity of 0.93, and an accuracy of 0.95 when compared with arthrography; 0.89, 0.92, and 0.90, respectively, when compared with arthroscopy and arthrotomy. MR imaging could also be used effectively to evaluate tears of the intercarpal ligaments, particularly the scapholunate ligament. Disruptions of the extrinsic ligaments, articular cartilage defects, and subluxations of the distal radioulnar joint were also well demonstrated. MR imaging is an effective procedure in assessing patients with chronic wrist pain.