CTArthrography, MR Arthrography, PET, and Scintigraphy in Osteoarthritis Patrick Omoumi, MD a,b , Gustavo A. Mercier, MD, PhD c , Fr ed eric Lecouvet, MD, PhD a , Paolo Simoni, MD a , Bruno C.Vande Berg, MD, PhD a, * Damage to articular cartilage is considered to be the hallmark of osteoarthritis (OA), even if other factors are involved in the pathogenesis of the disease. The radiological assessment of OA has been based mostly on the radiographic grading of the joint space width, an indicator of cartilage thickness, and on indirect signs such as osteo- phytes. 1–3 Attempts have been made to better delineate cartilage lesions by using intraarticular contrast material in arthrography, 4 which has inherent limitations due to the projection of three- dimensional structures on a plane. The advent of cross-sectional imaging enabled arthrography to develop further. 5–7 Indeed, arthrographic tech- niques such as computed tomography (CT) arthrography and magnetic resonance (MR) arthrography, thanks to their high resolution and the possibility of multiplanar imaging, remain superior to conventional MR imaging for the delin- eation of surface lesions of all cartilage areas. However, MR imaging is the only technique enabling the analysis of the internal structure of cartilage, and many recent developments include biochemical qualitative assessment. 2 The development of nuclear medicine tech- niques have focused mainly on the subchondral changes associated with OA, because there are no radiopharmaceuticals to image the articular cartilage in clinical practice. We review technical aspects of CT arthrography and MR arthrography of various joints, compare both methods, and report on their most common and useful indications, as well as their pitfalls and limitations. We also describe in detail the nuclear medicine methods that might be relevant for OA research and clinical application. CT ARTHROGRAPHYAND MR ARTHROGRAPHY Technical Considerations Type of contrast material with CT arthrography CT arthrography can be performed using either a single (iodine) or double-contrast (iodine and air) technique. In the past, air was used with conventional arthrography to distend the joints, which is not necessary when using CT, because the penetration of the air into cartilage lesions is poor when compared with that of fluid. Nowadays, there is a general consensus in using a single- contrast technique, which is easier to perform 8,9 and probably less painful. 10 Dilution of the contrast material can be achieved with local anesthetics or saline to avoid beam- hardening artifacts. Nevertheless, the dilution a Department of Radiology, Cliniques Universitaires Saint-Luc, Universite ´ Catholique de Louvain, Brussels, Belgium b Department of Radiology, Centre Hospitalo-Universitaire de Tours, Tours, France c Department of Radiology, Nuclear Medicine and Molecular Imaging, Boston University Center, Boston, MA, USA * Corresponding author. E-mail address: vandeberg@rdgn.ucl.ac.be (B.C. Vande Berg). KEYWORDS  CT arthrography  MR arthrography  PET  PET-CT  Scintigraphy  Osteoarthritis  Cartilage Radiol Clin N Am 47 (2009) 595–615 doi:10.1016/j.rcl.2009.04.005 0033-8389/09/$ – see front matter ª 2009 Published by Elsevier Inc. radiologic.theclinics.com