Ankle ligaments on MRI: appearance of normal and injured ligaments.

OBJECTIVE: The objective of our study was to provide a pictorial survey of MR images of ankle ligaments in various conditions from intact to disrupted. CONCLUSION: MR images of ankle ligaments from a sample of patients with ankle pain or injury are presented and reviewed.

MRI of isolated distal fibular fractures with widened medial clear space on stressed radiographs: which ligaments are interrupted?

OBJECTIVE: Patient management choices in ankle fractures remain controversial because of ambiguities in assessing ankle stability and lack of information on the integrity of all supporting ligaments. Our objective was to use MRI to identify the range of ankle ligament injuries associated with a problematic subset of ankle fracture: isolated fibular fractures for which widened medial clear space is absent or minimal on standard ankle radiographs but evident on stress images. CONCLUSION: In our retrospective study of 19 patients, we have categorized ligament injury and found partial or complete tears in all cases in at least two of the four major ligament groups--usually the deltoid and syndesmosis groups. The anterior inferior tibiofibular ligament of the syndesmosis suffered complete interruption in every case. The posterior tibiotalar ligament of the deltoid group, a major contributor to stability, was generally injured but, unexpectedly, most of these tears were partial.

MR imaging of the articular cartilage of the knee.

Magnetic resonance (MR) imaging of the knee is capable of accurately identifying and characterizing cartilage injuries and degeneration. Optimal cartilage imaging requires an understanding of the relationship between cartilage structure and the MR image, acquisition of images with adequate resolution, a purposeful interrogation of the images by a reviewer possessing an understanding of the appearance of tissue pathology as well as common pitfalls and artifacts, and finally, the accurate and consistent reporting of results.

Imaging of skeletal muscle.

Various diagnostic imaging techniques such as sonography, computed tomography, scintigraphy, radiography, and magnetic resonance imaging (MRI) have made possible the noninvasive evaluation of skeletal muscle injury and disease. Although these different modalities have roles to play, MRI is especially sensitive in the diagnosis of muscle disorders and injury and has proved to be useful in determining the extent of disease, in directing interventions, and in monitoring the response to therapies. This article describes how magnetic resonance images are formed and how the signal intensities in T1- and T2-weighted images may be used for diagnosis of the above-mentioned conditions and injuries.

MRI appearance of normal articular cartilage.

At each joint, the extracellular matrix of cartilage is arranged in a complex and characteristic organization that is specific for that joint. This structure exerts a strong influence on the appearance of magnetic resonance (MR) images through orientation-related alterations in T2 decay. As a result, the MR appearance of cartilage at each joint is predictable and specific for that joint. The diagnostic utility of MR imaging for evaluating cartilage is enhanced when the acquisition and review of the images is informed by an understanding of this relationship between normal structure and the MR appearance of cartilage.

Increased radiodensity of the proximal pole of the scaphoid: a common finding in computed tomography imaging of the wrist.

OBJECTIVES: To determine whether the proximal pole (PP) of the scaphoid is denser than the distal pole (DP) in a diverse population of patients undergoing computed tomography (CT) imaging of the wrist. METHODS: Sixty-nine patients who had CT of the wrist were retrospective reviewed. We measured CT density of the medullary bone of PP and DP of the scaphoid and calculated PP/DP ratio. To evaluate the variability of PP/DP ratio, we compared the ratios of these 3 groups. These patients were separated into 3 groups based on their diagnoses: group 1, healed scaphoids treated by casting; group 2, scaphoid nonunions; group 3, intact scaphoids. RESULTS: Proximal pole was denser than DP in most subjects. Proximal pole/distal pole ratio was similar among groups (P < 0.05). Fracture healing, sex, and age did not affect this ratio. However, we did not study scaphoids with avascular necrosis. CONCLUSIONS: Proximal pole was denser than DP in most of our subjects, including those with intact scaphoids, healing scaphoid fractures, and nonunions.

MRI of articular cartilage: revisiting current status and future directions.

OBJECTIVE: The purpose of this article is to review the current understanding of the MRI appearance of articular cartilage and its relationship to the microscopic and macroscopic structure of articular cartilage, the optimal pulse sequences to be used in imaging, the appearance of both degenerative and traumatic chondral lesions, the appearance of the most common cartilage repair procedures, and future directions and developments in cartilage imaging. CONCLUSION: Articular cartilage plays an essential role in the function of the diarthrodial joints of the body but is frequently the target of degeneration or traumatic injury. The recent development of several surgical procedures that hold the promise of forming repair tissue that is hyaline or hyalinelike cartilage has increased the need for accurate, noninvasive assessment of both native articular cartilage and postoperative repair tissue. MRI is the optimal noninvasive method for assessment of articular cartilage.

Leiomyosarcoma of the popliteal vein.

Primary vascular leiomyosarcomas are rare tumors arising from the media of vessel walls, involving the extremities in about one third of reported cases, and the popliteal vein even less frequently. We report a case of popliteal vein leiomyosarcoma in a 62-year old man who presented with leg pain and edema 4 weeks following spine surgery. Findings on ultrasound, MRI and CT angiography are reviewed, with particular emphasis on the value of CT angiography in fully evaluating the extent of the mass and in assisting percutaneous biopsy.

Macroscopic structure of articular cartilage of the tibial plateau: influence of a characteristic matrix architecture on MRI appearance.

OBJECTIVE: The purpose of our study was to describe the structural organization of the extracellular matrix of articular cartilage of the tibial plateau and its influence on MRI appearance. MATERIALS AND METHODS: Spin-echo images of 11 resected tibial plateaus acquired at 7 T were compared with the structure of the extracellular matrix as shown by fracture sectioning the samples in the plane of imaging. Four samples were scanned at two different orientations relative to the main magnetic field (B(0)). T2 maps were acquired in two orientations on three of these four samples. RESULTS: On the basis of the presence of reproducible regional variations in the shape of the matrix, a characteristic matrix architecture was described. The location of peak signal intensity and T2 on MRI correlated with the level at which the matrix was estimated to be aligned at approximately 55 degrees to B(0) (r = 0.91). This correlation of matrix orientation relative to B(0) with T2 and signal intensity on MRI was not altered by regional variations in the shape of the matrix or by imaging samples at two different orientations. CONCLUSION: The structure of the extracellular matrix, through its orientation-dependent influence on T2 decay, exerts a strong influence on the MRI appearance of cartilage. At the tibial plateau, a characteristic matrix architecture is associated with an equally characteristic MRI appearance.