Robert D. Boutin

Protocol issues for delayed Gd(DTPA)2–‐enhanced MRI (dGEMRIC) for clinical evaluation of articular cartilage

Biochemical and histologic data have validated the technique of delayed gadolinium‐enhanced MRI, in which the T1 values of cartilage after penetration of Gd(DTPA)2–allow assessment of the glycosaminoglycan (GAG) component of articular cartilage. This work describes the factors that have been found to be important for the practical implementation of the technique: 1) Exercise immediately after intravenous contrast administration was necessary for effective penetration of the contrast into the articular cartilage; 2) double‐dose contrast was better than single‐dose; 3) after contrast administration, a time window of 30–90 min for the hip, and 2–3 hr for all compartments of the knee proved to be appropriate for assessing articular cartilage; and 4) in some cases of hypointensities in the subchondral patellar bone, decreased penetration of the contrast agent into cartilage from bone was found. With the protocol described, ROIs on T1 images were reproducible within 15% on two separate imaging sessions, and initial clinical studies demonstrated the possible applications of the technique. Magn Reson Med 45:36–41, 2001.

UPDATE ON IMAGING OF ORTHOPEDIC INFECTIONS

Although the diagnosis of infection is only a small part of the orthopedists job description, it is a important part. This article discusses the fundamentals of orthopedic infections and highlights the refinements on this topic from a radiologic perspective. In addition to reviewing the imaging appearance of musculoskeletal infections in bone and the surrounding soft tissues, we focus on the advantages and disadvantages of five imaging methods: radiography, sonography, CT, scintigraphy, and MR imaging. Finally, we review three specific situations that have garnered substantial attention in recent medical literature: chronic recurrent multifocal osteomyelitis, musculoskeletal infections in AIDS patients, and pedal infections in diabetic patients.

Post-traumatic and stress-induced osteolysis of the distal clavicle: MR imaging findings in 17 patients.

Abstract Objective. To describe the MR imaging findings in patients with osteolysis of the distal clavicle and to compare the MR imaging appearance of clavicular osteolysis following acute injury with that related to chronic stress. Design and patients. MR imaging examinations were reviewed in 17 patients (14 men, 3 women; ages 16–55 years) with the diagnosis of post-traumatic or stress-induced osteolysis of the clavicle. A history of a single direct injury was present in seven patients and a history of weight-lifting, participation in sports, or repetitive microtrauma was present in 10 patients. Results. MR imaging showed edema in the distal clavicle in 17 patients and, of these, eight also had edema in the acromion. The edema was most evident in STIR and fat-suppressed T2-weighted pulse sequences. Other findings about the acromioclavicular (AC) joint were prominence of the joint capsule in 14, joint fluid in eight, cortical irregularity in 12, and bone fragmentation in six patients. No differences in the MR imaging features of post-traumatic and stress-induced osteolysis of the distal clavicle were observed. Conclusion. Post-traumatic and stress-induced osteolysis of the distal clavicle have similar appearances on MR imaging, the most common and conspicuous MR imaging feature being increased T2 signal intensity in the distal clavicle.

Magnetic resonance imaging of knee cartilage repair.

Cartilage injury resulting in osteoarthritis is a frequent cause of disability in young people. Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies for cartilage injury and degeneration.

Stress fractures of the lateral metatarsal bones in metatarsus adductus foot deformity: a previously unrecognized association.

Abstract Objective. To document a distinctive pattern of stress fractures in the lateral metatarsal bones of patients with metatarsus adductus foot deformity. Design and patients. Conventional radiographs and available medical records were reviewed in 11 patients (6 women, 5 men; ages 25–61 years) with stress fractures of the lateral (fourth or fifth) metatarsal bones and metatarsus adductus. Evaluation included the number and location of fracture(s), forefoot adduction angle, and qualitative assessment of bone mineral density. Conditions that might predispose patients to metatarsal fractures, including direct trauma, osteoporosis, and neuropathic osteoarthropathy were also recorded. Results. A total of 22 stress fractures were demonstrated, 17 of which involved the lateral metatarsals. A solitary fracture was present in six patients, while multiple fractures were evident in five patients. The sites of involvement were the fifth metatarsal (n=10), fourth metatarsal (n=7), third metatarsal (n=3), second metatarsal (n=1), and first metatarsal (n=1) bones. The locations of the stress fractures were in the proximal one-third of the metatarsal bones in 19 instances (86%) and in the middle one-third in three instances (14%). Forefoot adduction angle measured between 21° and 37° (normal range 8°–14°). Conclusion. Patients with metatarsus adductus may be at increased risk for stress fractures involving the lateral metatarsal bones, likely owing to the presence of altered biomechanics that place greater loads across the lateral aspect of the foot.

Spinous process fractures associated with Baastrup disease

Patients with Baastrup disease may experience pain owing to irritation of the periosteum or adventitial bursae between abutting spinous processes. We are not aware of any reports in the literature that describe stress fractures of the spinous fractures in patients with Baastrup disease. In this case report, we present two cases of spinous process fractures in lumbar vertebrae associated with Baastrup disease and describe their appearance with conventional radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance (MR) imaging.