Iliopsoas bursitis: diagnosis by MRI.

Iliopsoas bursitis is an unusual cause of hip pain. The condition may be due to athletic activity or may be secondary to a variety of inflammatory etiologies. An understanding of the anatomy and biomechanics of this structure is necessary to ensure prompt and appropriate radiologic diagnosis and clinical treatment. We report two cases of iliopsoas bursitis diagnosed with MRI and review the anatomy, pathophysiology, and treatment of this condition.

Using MR imaging to diagnose partial tears of the anterior cruciate ligament: value of axial images.

OBJECTIVE: The purpose of this study was to determine the usefulness of axial MR imaging for diagnosing partial anterior cruciate ligament (ACL) tears and to determine if patients could be categorized as having stable or unstable partial ACL tears on the basis of criteria of axial MR imaging. MATERIALS AND METHODS: We reviewed 238 patients who, over a 2-year period, underwent both MR imaging of the knee and arthroscopic evaluation of the ACL. According to arthroscopic examination, these patients had 143 normal ACLs, 67 complete ACL tears, and 28 partial tears. The 28 partial tears included 20 stable tears (no ACL deficiency) and eight unstable partial tears having ACL deficiency or requiring ACL reconstructive surgery. The axial MR images were retrospectively reviewed by two interpreters who were unaware of the arthroscopic findings, and decisions were reached by consensus. The ACL was classified according to its axial configuration and continuity. RESULTS: By axial MR imaging criteria, we found 109 elliptical ACLs, 45 attenuated ACLs, three ACLs with increased intrasubstance signal intensity, six isolated ACL bundle signs, 19 ACLs that could not be visualized, and 56 cloudlike mass signs. Arthroscopically normal ACLs and stable partial tears were difficult to distinguish reliably on axial MR images. Unstable partial ACL tears could not be distinguished from complete ACL tears. However, using axial MR imaging, our observers were able to segregate stable ACLs (normal ligaments and stable partial tears) from unstable ACLs (unstable partial tears and complete tears) with 100% sensitivity and 96% specificity. CONCLUSION: Axial MR imaging of the ACL may provide important diagnostic information for patients who have ACL injury. On axial MR images, stable ACLs were elliptical, attenuated, or showed as areas of increased intrasubstance signal intensity. At arthroscopy, attenuated ACLs represented normal ACLs (76%) and stable partial tears (24%). On axial MR images, the configurations that indicated unstable ligaments were isolated ACL bundle, nonvisualized ACL, and cloudlike mass.

MR imaging of the adult elbow.

Magnetic resonance (MR) imaging can provide important diagnostic information in the evaluation of the adult elbow. Optimal imaging technique should include the use of proper positioning, surface coils, and appropriate sequences and imaging planes as indicated by the suspected abnormalities. A familiarity with the anatomy of the normal elbow is crucial to identifying pathologic entities correctly and avoiding diagnostic pitfalls. Disruption of the collateral ligaments can best be demonstrated with thin-section coronal gradient-echo MR images. Injuries to the flexor and extensor muscle groups, biceps muscles, and triceps muscles require T2-weighted or short-inversion-time inversion recovery (STIR) MR images in the long and short axes of the affected muscle. The evaluation of osteochondral lesions and intraarticular bodies is optimized with T1-weighted and STIR MR images. Synovial processes usually necessitate the intravenous administration of gadopentetate dimeglumine to distinguish joint fluid from pannus. The contents of the cubital tunnel are best visualized on axial T1-weighted and STIR MR images. Masses arising in or near the elbow should be imaged with multiple sequences in at least two planes, and involvement of adjacent vital structures should be carefully evaluated.

MR imaging of sports injuries in the adult elbow: a tailored approach.

With an understanding of the normal anatomy of the elbow and a pertinent clinical history, MR imaging of the elbow need not be a source of fear and confusion for the MR radiologist. Because positioning and scan planning are not as straightforward as they are with other joints such as the knee or shoulder, these processes can be time-consuming. The position in which the patient is optimally scanned is inherently uncomfortable. In a busy MR center with rigorous time constraints, these factors and patient fatigue can limit the time available to acquire images. Thus, a tailored approach to designing a scanning protocol for the elbow is warranted. The preceding discussion attempts to address a streamlined approach to MR imaging of the more common pathologic processes occurring around the elbow. The sequences we have described may require some modification on different imaging systems to take into account variations in field strength and to account for disparity in hardware and software parameters of different vendors. In combination with the information provided in the clinical history, the guidelines we provide should serve as a general template upon which the practicing radiologist can base his or her approach to MR imaging of the elbow.

MR imaging of the rotator cuff mechanism: comparison of spin-echo and turbo spin-echo sequences.

OBJECTIVE: Although well documented in other MR imaging applications, the value of turbo spin-echo sequences in evaluating the shoulder has not been addressed. This study was designed to directly compare matched spin-echo and turbo spin-echo sequences in the MR imaging evaluation of the rotator cuff. MATERIALS AND METHODS: Using otherwise matched double-echo sequences of equal time duration, we performed 123 paired spin-echo (TR/TE, 200/25,75; one excitation) and turbo spin-echo (3500-5000/22,90; two excitations) sequences in the paracoronal and/or parasagittal plane of the shoulders of 76 patients referred to our institution for possible rotator cuff tear. The sequences were retrospectively analyzed for cuff signal and morphology, fluid conspicuity, coracoacromial arch morphology, and bone marrow signal abnormalities. Surgical and nonsurgical clinical results were correlated when available. RESULTS: We found 100% diagnostic correlation between spin-echo and turbo spin-echo sequences for rotator cuff integrity. Surgical data were available for 26 patients, and clinical follow-up for another 37. For complete rotator cuff tear in the surgical subpopulation, sensitivity was 89%, specificity was 94%, and diagnostic accuracy was 24 of 26 (92%). We found no diagnostically significant difference between the two imaging sequences for fluid conspicuity, coracoacromial morphology, or marrow signal. Signal-to-noise ratios were superior in the turbo spin-echo sequences. CONCLUSION: Turbo spin-echo sequences are an accurate and efficient tool in the MR imaging evaluation of the rotator cuff. Potential benefits include time saving, increased spatial resolution, and improved signal-to-noise ratio.

MR imaging of the posterior cruciate ligament: normal, abnormal, and associated injury patterns.

The posterior cruciate ligament (PCL) of the knee has received little attention in the radiology literature, but its importance in knee stability has come under close scrutiny in recent years. Unrepaired injury of the PCL can lead to chronic instability and early joint degeneration. Three major mechanisms of trauma that involves the PCL are posterior displacement of the tibia in a flexed knee, hyperextension, and rotation combined with an adduction or abduction force. The spectrum of PCL injuries includes partial tear or intrasubstance injury, complete ligamentous rupture, and avulsion of the PCL insertion site on the posterior tibia. Associated injuries include injury of other ligaments, meniscal tear, bone injury, and joint effusion. PCL rupture is easily identified with magnetic resonance (MR) imaging by using simple signal intensity and structural characteristics. Because clinical and arthroscopic assessment of the PCL can be difficult, MR imaging can be valuable for evaluating the acutely injured knee when operative repair of the PCL is being considered.

MR imaging appearance of the extensor mechanism of the knee: functional anatomy and injury patterns.

Trauma to the extensor mechanism of the knee, a common clinical problem, can be accurately evaluated with magnetic resonance (MR) imaging. The extensor mechanism consists of the quadriceps muscle and tendon, patella, patellar tendon, and patellar retinacula. Injuries of these structures can be classified into partial and complete tears. Acute injuries are associated with edema, hemorrhage, and fluid collections; chronic injuries often demonstrate redundancy, atrophy, and retraction of the affected structures. MR imaging is useful in differentiating partial and complete tears and in evaluating tissue edema and hemorrhage. It also allows detection of unsuspected nondisplaced patellar fractures and chronic conditions due to repetitive trauma. Transient dislocation of the patella is an often clinically unsuspected entity for which MR imaging can serve an important diagnostic role. A detailed understanding of the functional and anatomic relationships of the extensor mechanism can greatly assist in interpretation of MR images of the traumatized knee.

Magnetic resonance imaging of the extensor mechanism.

Trauma involving the extensor mechanism of the knee is a fairly common clinical problem, and can be addressed easily with a basic understanding of the anatomy of the involved structures. Injury to the muscles and tendons of this group is categorized broadly into complete versus partial tears based on the respective absence or presence of intact fiber bundles. Acute injuries are associated with edema, hemorrhage, and fluid collections; chronic injuries often demonstrate redundancy, atrophy, and retraction. Fracture of the patella can be related to direct or indirect trauma, and is functionally equivalent to a complete tear of the musculotendinous elements. Tendinitis is a more chronic condition seen with repetitive trauma, and usually affects the proximal aspect of the patellar tendon. Swelling and abnormal intrasubstance signal are commonly associated with this entity.

Posterior cruciate ligament injury: MR imaging diagnosis and patterns of injury.

PURPOSE: To illustrate the variety of posterior cruciate ligament (PCL) injuries and assess the type and frequency of associated knee injuries. MATERIALS AND METHODS: In a retrospective review of 1,950 magnetic resonance (MR) examinations of the knee, 47 patients with MR imaging findings of PCL injury were identified. In 24 patients, the findings on MR images were correlated with athroscopic findings (n = 14) or findings at physical examination (n = 10). Patterns of associated injuries were described and tabulated. RESULTS: Twenty-one patients (45%) had complete PCL tears; 22 patients (47%), partial tears; and four patients (9%), bone avulsion. Associated injuries were seen in 34 patients (72%). Patterns of injuries differed from those seen in anterior cruciate ligament injury and correlated with the mechanism of trauma. CONCLUSION: MR imaging proved accurate in assessment of the PCL in patients with clinical correlation and demonstrated patterns of associated injury that may affect management strategy.

Staging lung carcinoma with a Tc-99m labeled monoclonal antibody.

Thirty-three patients with biopsy-proven lung cancer and a total of 150 lesions diagnosed by conventional staging procedures were imaged using a Tc-99m labeled monoclonal Fab fragment of an IgG2B murine monoclonal antibody (MoAb) (NR-LU-10, NeoRx Corporation). Immunoscintigraphy demonstrated 100% of primary and 78% of metastatic lesions. MoAb imaging detected 88% of lesions in 12 small cell lung cancer (SCLC) patients and 77% of lesions in 21 non-small cell lung cancer (NSCLC) patients. Based on initial evaluation by other methods, 29 sites of MoAb activity were not associated with evidence of disease. Eleven of these were subsequently shown to represent sites of metastases; 18 remain unconfirmed. Four of ten patients studied with limited NSCLC had eight unsuspected lesions on MoAb imaging. Confirmation of unsuspected lesions in two patients altered initial clinical staging, and surgical therapy was abandoned. This study demonstrates that Tc-99m labeled NR-LU-10 can accurately stage patients with lung cancer.

Obstruction of the inferior vena cava: a multiple-modality demonstration of causes, manifestations, and collateral pathways.

This article explores the causes and manifestations of obstruction of the inferior vena cava (IVC) with a multiple-modality approach. Caval obstruction may be due to thrombus, extension of a tumor, extrinsic compression, or intrinsic caval disease. Evaluation of the IVC should be tailored to the individual circumstance; no single modality is best in all situations. Although magnetic resonance offers multiplanar imaging, vena cavography or ultrasound are often necessary to exclude intraluminal tumor extension. Computed tomography is sensitive for intracaval thrombus and compression but does not delineate the hepatic IVC well. Nuclear venography demonstrates well the resultant collateral pathways, which can be separated into the deep, intermediate, superficial, and portal systems. Despite the clear visualization of these pathways with this modality, congenital caval anomalies, such as caval interruption with azygos continuation, can be confused with acquired caval disease.