Determination of left ventricular mass by single-photon emission computed tomography with thallium-201

To test the hypothesis that single-photon emission computed tomography (SPECT) might permit accurate, noninvasive measurement of LV mass, SPECT measurements of LV mass to LV weight were compared in 20 mongrel dogs. Projection images of the left ventricle were acquired after intravenous injection of thallium-201 (TI-201). Transverse sections were reconstructed using filtered backprojection. Coronal sections were extracted from the reconstructed volume. The boundary of LV uptake of TI-201 in each coronal section was defined automatically using a threshold detector. Scintigraphic LV mass [total number of volume elements (voxels) showing TI-201 uptake X voxel volume X specific gravity of myocardium] was compared to actual LV weight. There was good correlation between scintigraphic LV mass and LV weight. Mean LV weight was 68 +/- 20 g (+/- standard deviation) (range 27 to 94). Mean SPECT LV mass was 66 +/- 19 g (range 28 to 100). Linear regression analysis yielded the following relation: SPECT LV mass = 0.87 X LV weight + 6.79 (r = 0.91, root-mean-square deviation from regression = 7.5). SPECT measurements were reproducible, with a coefficient of variation of 0.24%. Thus, SPECT of LV TI-201 distribution can be used to measure LV mass in canine myocardium.