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Magnetic resonance imaging represents a relevant way to diagnostically assess the wrist with high-resolution, multipla- nar imaging without employing ioniz- ing radiation. It influences clinical and surgical diagnosis and management of wrist pathologies.1 This article will dis- cuss typical indications for advanced imaging of the wrist, including post- traumatic lesions, avascular necrosis, chondral injuries and arthritis, tendon pathologies and internal derangements of ligaments and the triangular fibrocar- tilage complex (TFCC).
MRI protocol
While varying among institutions, a typical wrist MRI protocol is shown in Table 1. It employs a small field of view (8 to 10 cm), and section thick- ness varies from 2mm to 3mm. A thin- ner section sequence (up to 1mm) is normally added (2D or 3D GRE T2* or more recent volumetric 3D turbo spin echo proton density fat saturation se- quences), which allows for multiplanar reconstruction in isotropic acquisitions. 3T MRI is preferable to 1.5T, given the better signal-to-noise ratio, contrast, and resolution of the images, all of which increase diagnostic accuracy.2 Direct or indirect MR arthrography (for both 1.5T and 3T) is employed as the standard of care in many institutions for assessing internal derangement, as multiple stud- ies demonstrate the accuracy advantage of these techniques, particularly of 3T MR arthrography. However, whether arthrography is necessary for all cases remains unclear. Given the technologi- cal advances in MRI systems, dedicated coils and new sequences, the authors perform 3T MRI as a default at our insti- tution, and reserve arthrography for se- lected postoperative cases, or for cases of clinical-radiological mismatch in which surgery is being considered.3-8 8
Bones and cartilage
Occult fractures are detected as linear, low signal intensity on the T1-weighted sequence with surrounding bone marrow edema (Figure 1). Areas of bone contu- sion are differentiated mainly by the ab- sence of a clear fracture line (Figure 2).9 Typical areas include the scaphoid, the tubercle of trapezium (radial-sided pain), the hook of the hamate (ulnar/volar- sided pain) and the distal radius.
Avascular necrosis (AVN) of the lu- nate (Kienbock's disease) is character- ized initially by high signal intensity on fluid sensitive sequences, with low signal intensity on all sequences later in disease progression. A typical coronal plane frac- ture and bone fragmentation may follow, with further progression...