Radiology, Vol 206, 339-345, Copyright © 1998 by Radiological Society of North America
Assessment of dorsal or ventral intercalated segmental instability configurations of the wrist: reliability of sagittal MR images
M Zanetti, J Hodler and LA Gilula
Department of Radiology, Balgrist Clinic, University of Zurich, Switzerland.
PURPOSE: To determine whether a dorsal intercalated segmental instability
(DISI) or ventral intercalated segmental instability configuration can be
mimicked on sagittal magnetic resonance (MR) images in asymptomatic
subjects with unremarkable lateral radiographs. MATERIALS AND METHODS: In
10 asymptomatic adult volunteers, capitolunate, scapholunate, and
radiolunate angles were measured on lateral radiographs and compared with
those measured on T1-weighted spin-echo MR images obtained in neutrally
positioned wrists with subtle variations in the sagittal imaging plane. MR
measurements also were obtained in 15 degrees radially and 15 degrees
ulnarly deviated wrists. RESULTS: In neutrally positioned wrists, the mean
capitolunate, scapholunate, and radiolunate MR angles were 13.6
degrees-14.5 degrees, 4.0 degrees-9.9 degrees, and 18.0 degrees-20.3
degrees larger, respectively, than those on lateral radiographs. In 15
degrees radially deviated wrists, the mean MR angles were similar to those
on lateral radiographs. In 15 degrees ulnarly deviated wrists, the mean MR
angles were 32.3 degrees, 16.6 degrees, and 37.1 degrees larger than those
on lateral radiographs. At MR imaging, a DISI configuration would have been
diagnosed in four subjects with neutrally positioned wrists and in eight
subjects with ulnarly deviated wrists. CONCLUSION: The lunate appears more
dorsally tilted on sagittal MR images than on lateral radiographs, and a
DISI configuration can be mimicked. Subtle errors in the selection of the
imaging plane do not substantially influence measurements; however, wrist
positioning is crucial.
