Short-axis circumferential profiles of the heart in healthy subjects: comparison of T1-201 SPECT and two-dimensional echocardiography

To correlate the findings at thallium-201 single photon emission computed tomography (SPECT) with left ventricular anatomy, circumferential wall thickness was measured in 12 healthy subjects with two-dimensional echocardiography. At the midpapillary level, eight anatomic structures were identified with echocardiography, as were four maxima (papillary muscles and junctions of the left ventricular myocardium with the right ventricle, both anteriorly and posteriorly) and the intervening minima (including the septum). Tl-201 SPECT was performed in the same subjects. The normalized circumferential count profiles of the short-axis sections that included the papillary muscles showed the same basic pattern as that on echocardiograms. In most cases, the posterior papillary muscle and the posterior junction with the right ventricle were not distinguishable from each other, which produced three circumferential profile maxima instead of four. When values from all subjects were averaged, left ventricular anatomy was less evident in the circumferential profile. Left ventricular anatomic structures were reflected to a similar degree with either 180 degrees or 360 degrees data sampling.