NONINVASIVE MEASUREMENT OF HUMAN ASCENDING COLON VOLUME

The capacitance and motor functions of the colon are important determi nants of its overall function. A simple, noninvasive method to quantif y regional colonic volume is required for further physiologic and phar macologic studies. Our aim was to determine whether measurements of hu man ascending colon (AC) volume using two-dimensional (2-D) images are as accurate as estimates using three-dimensional (3-D) images. Five h ealthy male volunteers each ingested a methacrylate-coated capsule con taining Tc-99m-labelled Amberlite pellets. Two- and 3-D images were ob tained using a gamma camera with single photon emission computed tomog raphy (SPECT) capability. Ascending colon volume was estimated by a va riable region of interest (VROI) program and by full-width half-maximu m (FWHM) analysis, and results were compared to the volume estimates b y SPECT. Full-width half-maximum analysis yielded volume estimates tha t were not significantly different from SPECT (slope = 1.093; t = 0.51 ; P>0.5), whereas VROI estimates were significantly different from vol ume measurements by SPECT and, hence, considered less accurate (slope = 0.438; t = 4.93; P<0.02). Thus, the less expensive and more easily a vailable planar imaging technique with analysis by FWHM estimates AC v olume as accurately as SPECT.