Thallium-201 myocardial imaging for evaluation of cardiomyopathy

The usefulness of thallium-201 myocardial scintigraphy (TMS) was evaluated in 27 patients with cardiomyopathy, in comparison with hemodynamic and echocardiographic findings. The patients were 6 cases of hypertrophic obstructive cardiomyopathy (HOCM), 15 of hypertrophic non-obstructive cardiomyopathy (HCM) and 6 of congestive cardiomyopathy (CCM). Interventricular septal thickness in TMS was compared with echocardiographic estimate. Although favorable correlation was obtained between scintigraphic (in gated image) and echocardiographic estimates, no significant correlation was found between scintigraphic (in ungated image) and echocardiographic estimates. Similar correlation were also obtained between scintigraphic (in gated image) and echocardiographic estimates of posterior wall thickness and the ratio of interventricular septal to posterior wall thickness. The patients with CCM had a marked increase in left ventricular transverse diameter compared to those with HOCM or HCM. The mean pulmonary arterial wedge pressure in patients with CCM was significantly higher than that in patients with HCM. Right ventricular free wall was visualized in 5 of 6 cases with CCM, but it was visualized only in 2 of 15 cases with HCM. Right ventricular free wall was not visualized in all patients with HOCM. Of the 27 patients with cardiomyopathy, there were 5 patients with equivocal perfusion defect and 22 normal studies. The location of equivocal perfusion defect was apical in 4 of 5 cases. Multiple perfusion defects were seen in the patient with ischemic cardiomyopathy. (author)