Establishment of carpal contents/canal ratio by means of magnetic resonance imaging.

Magnetic resonance imaging (MRI) was used to determine cross-sectional areas and volumes of carpal canals and carpal canal contents in five cadaver specimens in an assessment of the reliability of MRI for establishing contents/canal ratios. Volumes of the carpal canals and their contents were accurately calculated from MRI with a previously described correction factor (0.8161) for carpal tunnel volumes and a calculated correction factor (1.078) for carpal tunnel contents volume. There was no significant difference between laboratory-measured or MRI-calculated ratios from either volumes (p = 0.86) or surface areas (p greater than 0.79). Cross-sectional area contents/canal ratios were significantly higher (p = 0.0001) at the level of the distal aspect of the hook of the hamate (0.54) as compared with those at the level of the distal radial styloid (0.42) and proximal metacarpals (0.44). MRI provides an effective and reliable means of determining contents/canal ratios from both cross-sectional area and volume calculations.