Application of magnetic resonance imaging to ischemic necrosis of the lunate.

Twenty patients (22 wrists), in whom ischemic necrosis of the lunate was suspected clinically, were studied prospectively by physical examination, conventional radiography, radionuclide bone scintigraphy, and magnetic resonance imaging. Magnetic resonance imaging showed more specificity than radiography or radionuclide bone imaging in making the diagnosis of ischemic necrosis of the lunate. Two patterns of lunate signal defect were seen on magnetic resonance imaging with focal or generalized signal loss on T1-weighted and T2-weighted images. Generalized loss of lunate signal on T1-weighted images was diagnostic for ischemic necrosis of the lunate. Focal signal loss on the radial one half of the lunate suggested early involvement. Normal or increased signal on the corresponding T2-weighted image implied an earlier stage and a better prognosis. Magnetic resonance imaging evaluation of the lunate may be useful for subclassification of Lichtman's radiographic stage 2 and can be employed to follow lunate revascularization after treatment. Magnetic resonance imaging is a low risk, noninvasive diagnostic technique, which can modify diagnosis, staging, treatment and prognosis of ischemic necrosis of the lunate.