Magnetic Resonance Arthrography of the Wrist and Elbow

Magnetic Resonance Arthrography of the Wrist and Elbow Gary M. LiMarzi, MDa,b, M. Cody O’Dell, MDa,b, Kurt Scherer, MDa,b, Christopher Pettis, MDa,b, Christopher W. Wasyliw, MDa,b, Laura W. Bancroft, MDa,b,* KEYWORDS MR arthrography Scapholunate ligament tear Ulnar collateral ligament tear Olecranon stress fracture Osteochondritis dissecans KEY POINTS Magnetic resonance (MR) arthrography is highly sensitive and specific for the diagnosis of scapholunate ligament tears. MR dictations should state if tears are partial-thickness or full-thickness, and if the tearing involves the dorsal, membranous, and/or volar components of the ligament. Partial-thickness tears of the anterior band of the ulnar collateral ligament in overhead-throwing athletes are well evaluated with MR arthrography. Repetitive valgus elbow stress and rapid elbow extension during the late stages of throwing may result in an olecranon stress fracture, with propagation from a structural weak point in the trochlear groove. Osteochondritis dissecans of the elbow is an osteochondral injury classically seen in adolescent or young adult athletes, especially baseball pitchers, due to repetitive valgus impaction injury of the radial head and developing ossification center of the capitellum. MAGNETIC RESONANCE ARTHROGRAPHY OF injuries to the intrinsic and extrinsic carpal liga- THE WRIST ments, as well as the triangular fibrocartilage com- plex (TFCC). Because the TFC is discussed in Wrist pain is a common, nonspecific patient depth in the article by Cody et al, elsewhere in complaint that may be secondary to a variety of this issue, this article will not focus on its normal im- underlying processes, both degenerative and trau- aging appearance or pathology. Because clinical matic. Wrist trauma can be divided into 2 cate- presentations can overlap significantly, magnetic gories: low impact and high impact. High-impact resonance (MR) arthrography is essential in the trauma can lead to displaced fractures, disloca- diagnostic workup of such injuries. MR arthrogra- tions, and acute tears of the ligaments and tendons, phy of the wrist is generally preferred over conven- whereas low-impact trauma can lead to more 1 tional MR imaging or computed tomography (CT) occult injuries. Both mechanisms can result in arthrography because of its high intrinsic contrast The authors have nothing to disclose. a Florida Hospital Diagnostic Radiology Residency Program, Department of Radiology, Florida Hospital, Uni- versity of Central Florida College of Medicine, 601 East Rollins, Orlando, FL 32803, USA; b Department of Radi- ology, Florida Hospital, University of Central Florida College of Medicine, 6850 Lake Nona Boulevard, Orlando, FL 32827, USA * Corresponding author. E-mail address: [email protected] Magn Reson Imaging Clin N Am 23 (2015) 441–455 http://dx.doi.org/10.1016/j.mric.2015.04.003 1064-9689/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved. mri.theclinics.com 442 LiMarzi et al resolution, as well as the ability to evaluate extra- articular soft tissue pathology. MR arthrography is indicated to evaluate TFCC, intrinsic and extrinsic carpal ligaments, and the distal radial ulnar joint (DRUJ).2 Technique The use of intra-articular contrast agents provides an effective means of evaluating the TFCC and interosseous ligaments of the wrist. There is vari- ability among institutions as to whether to perform single-compartment (most commonly radiocarpal), 2-compartment, or rarely 3-compartment (radiocarpal, DRUJ, and midcarpal) arthrography before MR arthrography. Injections are most commonly performed under fluoroscopic guidance, but some radiologists prefer sonographic guidance.3 Radiocarpal injections are approached most Fig. 1. Wrist arthrogram in a 70-year-old man before commonly from a dorsal approach; however, MR arthrography. Anteroposterior view of the wrist 4 some radiologists choose a lateral approach. at the beginning of arthrogram demonstrates radio- With the patient supine on the fluoroscopy table, carpal injection of 1:250 ratio of gadolinium to iodin- the patient’s wrist is placed in a flexed position ated contrast through a 25-gauge needle (arrowhead) and bolstered with a rolled towel. The radiocarpal before MR arthrogram. Asterisk indicates site for mid- joint is visualized in profile and the skin overlying carpal injection, and circle indicates site for distal the joint is marked at the level of the mid scaphoid. radioulnar injection. After prepping and draping the dorsum of the wrist, local anesthesia is administered with a 25-gauge, Midcarpal joint injections are most commonly 1.5-inch anesthesia needle from a dorsal performed from a dorsal approach into to the cen- approach, and the needle is advanced into the tral portion of the 4-part junction of the lunate, tri- radiocarpal joint. Connector tubing flushed with quetrum, hamate, and capitate. Distal radioulnar injectate from the syringe is connected to the nee- joint injection is performed from a dorsal dle after dripping contrast into the needle hub to approach, with the needle extending to the radial displace any air. Although some radiologists inject aspect of the ulnar head. only a small amount of iodinated contrast to confirm needle placement before injecting the Contraindications dilute gadolinium mixture, it is also acceptable to combine the iodinate contrast and gadolinium Besides the normal contraindications for MR together. While taking rapid cine images, an imaging, the only absolute contraindication for ar- approximately 3-mL mixture of iodinated contrast thrography is local infection of the skin or subcu- 5 and dilute gadolinium is injected into the radiocar- taneous tissue. One would not want to pal joint, or until resistance is perceived (Fig. 1). contaminate a joint by crossing a needle through The gadolinium-based contrast used in MR ar- infected tissues. Usually, patients who cannot un- thrography is usually diluted in normal saline and/ dergo MR arthrography are able to tolerate imag- or iodinated contrast to a concentration of 1:250, ing with CT arthrography. For example, patients which optimizes the paramagnetic effects of gado- with implantable cardiac pacemakers who, with linium at 1.5-T field strengths. After removal of the some recent exceptions due to new MR imaging- needle, the wrist is then briefly exercised and con- safe pacemakers, cannot undergo MR arthrogra- 5–8 ventional arthrographic images are obtained in the phy, can be safely evaluated with CT. A history anteroposterior, lateral, and oblique images before of adverse contrast reactions with either iodinated MR arthrography. Some radiologists also prefer or gadolinium-based agents is considered a rela- taking dedicated spot imaging of the scapholunate tive contraindication and should be evaluated on 5 (SL) ligament with ulnar deviation or clenched fist a case-by-case basis. stress maneuver. This arthrographic imaging is Complications diagnostic, and is instrumental in cases of patients unable to complete the MR portion of the examina- Arthrography is a generally well-tolerated proce- tion for a variety of reasons. dure with few significant risks, and complications MR Arthrography of the Wrist and Elbow 443 following arthrography are uncommon and usually in the form of pain. This can be due to overdisten- tion of the joint space, irritation of surrounding nerves, or from intravasation of injected contrast into adjacent muscles.5,7,8 Synovitis caused by the contrast also may be irritating and painful. Infection is an inherent risk to all percutaneous procedures, but is very rare. Magnetic Resonance Acquisition Wrist MR arthrography should be obtained on a 1.5-T or preferably a 3.0-T magnet in a dedicated wrist coil for optimal image quality, and thin- Fig. 2. Axial scout for prescription of coronal and section imaging and small field of view should be sagittal views. A plane intersecting the hook of the 9–13 used (Table 1). Patients are optimally scanned hamate (H) and the palmar margin of the trapezium in the prone position with the arm extended over- (T) serves as the reference plane for coronal acquisi- head and the wrist in neutral positioning near the tions (single line). Sagittal images are prescribed isocenter of the magnet (“Superman” position).13 from the axis perpendicular (double lines) to the cor- If patients cannot tolerate this positioning, imaging onal plane. is done with the wrist by the patient’s side, with care to optimize fat suppression. MR arthrography includes axial, coronal, and sagittal imaging also prefer using gradient-echo sequences or planes, and the coronal and sagittal sequences 3-dimensional volumetric sequences. Although are prescribed relative to a plane intersecting the uncommonly used, some investigators use finger hook of the hamate and the palmar margin of the trap distraction with weights suspended from the trapezium (Fig. 2). Most sequences are obtained fingers to accentuate the amount of contrast in with turbo spin echo (TSE) T1-weighting with fat the SL interval, widening of the space, and disrup- 14,15 suppression, to take advantage of the T1 proper- tion of Gilula carpal arcs. ties of the injected gadolinium; T1-weighted images without fat suppression and T2-weighted NORMAL ANATOMY images with fat suppression also are obtained. Intrinsic Ligaments T2-weighted fat-suppressed and non–fat-suppressed T1-weighted images are useful in evalu- The intrinsic and extrinsic interosseous ligaments ating the marrow. T2-weighted images can of the wrist

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