ASSESSMENT OF MYOCARDIAL VIABILITY IN PERSISTENT DEFECTS ON TL-201 SPECT AFTER REINJECTION USING GRADIENT-ECHO MRI

This prospective study assessed myocardial viability in 30 patients wi th coronary heart disease and persistent defects despite reinjection o n TI-201 single-photon computed tomography (SPECT). In each patient, t hree observers graded TI-201 uptake in 7 left ventricular wail segment s. Gradient-echo magnetic resonance imaging in the region of the persi stent defect generated 12 to 16 short axis views representing a cardia c cycle. A total of 120 segments were analyzed. Mean end-diastolic wai l thickness and systolic wall thickening (+/- SD) was 11.5 +/- 2.7 mm and 5.8 +/- 3.9 mm in 48 segments with normal TI-201 uptake, 10.1 +/- 3.4 mm and 3.7 +/- 3.1 mm in 31 with reversible lesions, 11.3 +/- 2.8 mm and 3.3 +/- 1.9 mm in 10 with mild persistent defects, 9.2 +/- 219 mm and 3.2 +/- 2.2 mm in 15 with moderate persistent defects, 5.8 +/- 1.7 mm and 1.3 +/- 1.4 mm in 16 with severe persistent defects, respec tively. Significant differences in mean end-diastolic wall thickness ( p < 0.0005) and systolic wall thickening (p < 0.005) were found only b etween segments with severe persistent defects and all other groups, b ut not among the other groups. On follow-up in 11 patients after revas cularization, 6 segments with mild-to-moderate persistent defects show ed improvement in mean systolic wall thickening that was not seen in 6 other segments with severe persistent defects. These data indicate th at most myocardial segments with mild and moderate persistent TI-201 d efects after reinjection still contain viable tissue. Segments with se vere persistent defects, however, represent predominantly nonviable my ocardium without contractile function.