Magnetic resonance imaging, computed tomographic and anatomical correlation of dimensions of the metacarpal and proximal phalanx of the little finger

Abstract

This study documents the transverse dimensions of the proximal phalanx and metacarpal of the little finger in Chinese hands, and correlates these with measurements obtained by CT and MR imaging. The study group consisted of fifty embalmed Chinese cadaver hands. The proximal phalanx and metacarpal of each little finger were examined by CT and MR imaging, followed by dissection. Axial CT and MR scans were performed through the proximal base (D1), mid-shaft (D2) and distal head (D3) of the fifth metacarpal and of the proximal phalanx (D4, D5 and D6) in these fifty hands. The following dimensions were measured: outside diameter (D) on both AP and TR views, and inside diameter (d) on both AP and TR views. The percent coefficient of variation (%CV) was lower in the group of outside diameters than in the group of inside diameters. Correlation between CT and MR imaging, and cadaveric specimen dimensions was generally fair (P<0.05), although MR imaging tended to underestimate D5. There was no correlation between MR imaging and CT, and between MR imaging and cadaveric specimen for inside diameter dimensions. MR imaging is adequate for measuring the transverse dimensions of the external dimensions of the metacarpals and phalanges but suffer from the disadvantage of not being able to reliably measure the inner dimensions. To design good implants for fixation and hand fractures, evaluation using CT is recommended.