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Cartilage injuries are common, especially in athletes. Because these injuries frequently affect young patients, and they have the potential to progress to osteoarthritis, treatment to alleviate symptoms and delay joint degeneration is warranted. A number of surgical techniques are available to treat focal chondral defects, including marrow stimulation, osteochondral auto- and allografting, and autologous chondrocyte implantation. Although arthroscopy is considered the standard of reference for the evaluation of cartilage before and after repair, it is invasive with associated morbidity and cannot adequately depict the deep cartilage layer and underlying bone. Magnetic resonance (MR) imaging provides unparalleled noninvasive assessment of the repair site and all other joint tissues. MR observation of cartilage repair tissue is a well-established semiquantitative scoring system for repair tissue that has primarily been used in clinical research studies. The cartilage repair osteoarthritis knee score (CROAKS) optimizes comprehensive morphologic assessment of the knee joint after cartilage repair. Furthermore, quantitative, compositional MR imaging measurements (eg, T2, T2*, T1ρ), delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC), and sodium imaging are available for biochemical assessment. These quantitative MR imaging techniques help assess collagen content and orientation, water content, and glycosaminoglycan and/or proteoglycan content both in the repair tissue as it matures and in the "native" cartilage. In this review, the authors discuss the principles of state-of-the-art morphologic and compositional MR imaging techniques for imaging of cartilage repair and their application to longitudinal studies., ((©) RSNA, 2015.)

The purpose of this HIPAA-compliant study was to prospectively evaluate the feasibility of contrast material-enhanced computed tomography (CT) with digital bone masking for the evaluation of synovitis and tenosynovitis in patients with rheumatoid arthritis. Four patients with rheumatoid arthritis and findings at magnetic resonance (MR) imaging were evaluated after informed consent for this institutional review board-approved study was obtained. To improve the conspicuity of synovial enhancement, postcontrast CT was performed with a relatively low kilovoltage and high iodine concentration and precontrast images were used as a subtraction mask to eliminate high-attenuation cortical bone contours. Moderate to high agreement between CT and MR imaging findings for synovitis and tenosynovitis was demonstrated, which suggests that this technique may be an acceptable alternative to MR imaging in the evaluation of rheumatoid arthritis., ((c) RSNA, 2009.)

Purpose: To evaluate the use of magnetic resonance (MR) imaging during manual positioning of the hip, or multipositional MR imaging, in an open-magnet configuration to study femoral head containment, articular congruency, and femoral head deformity in Legg-Calvé-Perthes disease., Materials and Methods: In 12 children with advanced Legg-Calvé-Perthes disease, multipositional MR imaging and conventional arthrography were compared in the assessment of containment, femoroacetabular congruency, and femoral head deformity. Images of the hips in several positions were compared subjectively and objectively., Results: MR imging correlated well with arthrography for overall subjective assessment of severity of disease (r = 0.71, P = .01), with good interobserver agreement (kappa = 0.65, P < .001). MR images demonstrated all cases of hinge abduction shown arthrographically. However, MR imaging failed to depict one case of femoral head flattening. MR imaging correlated well with arthrography in the objective evaluation of joint fluid and lateral subluxation (r = 0.80, P < .01). MR imaging correlated poorly with arthrography in the measurement of sphericity of the femoral head., Conclusion: Multipositional MR imaging with an open-magnet configuration was comparable to arthrography for demonstration of femoral head containment and congruency of the articular surfaces of the hip. In the evaluation of deformity, it performed less well.

This study reports findings on joint fluid enhancement after intravenous administration of gadopentetate dimeglumine. Ten subjects were studied: two asymptomatic volunteers and eight patients with suspected meniscal tears. The subjects underwent imaging at 1.5 T before, immediately after, and 42-60 minutes after intravenous administration of gadopentetate dimeglumine. The rate of fluid enhancement was assessed in three subjects, and the effects of exercise were studied. All subjects exhibited enhancement of joint fluid. Mean fluid enhancement for patients was 137% on initial and 262% on delayed images obtained after exercise. Exercise increased the rate and degree of fluid enhancement and distributed contrast material uniformly throughout the joint. The arthrographic effect of the fluid enhancement increased the number of perceived cartilage defects. This study documents enhancement of joint fluid in healthy subjects and in those with effusions. The arthrographic effect may provide a more convenient alternative to intraarticular injection of gadopentetate dimeglumine for MR arthrography.

The formation of a bony bridge across the growth plate was studied with magnetic resonance (MR) imaging, tomography, and histologic examination in 12 rabbits. Histologic studies performed 0-8 weeks after the creation of a defect in the physis demonstrated transphyseal bone formation with no evidence of cartilage repair. Gadolinium enhancement indicated the development of vascularity through the plate, which preceded the formation of a bony bridge. Enhancement was faint at 4 days after surgery, was inhomogeneous at 1 week, was maximal at 2 weeks, and decreased at 3 weeks and beyond as the lesion was replaced by bone. A dark rim representing bone deposition at the periphery of the lesion was seen at 2 weeks. At 4 weeks and beyond, the bridge was seen as a dark band of dense bone or as a wider area that was isointense with adjacent fatty marrow. Abnormality in the cartilage and development of transphyseal vascularity, which precede the formation of a bony bridge after trauma, can be detected with MR imaging.