Assessment of systolic wall thickening using technetium-99m methoxyisobutylisonitrile in patients with coronary artery disease: relation to thallium-201 scintigraphy with re-injection

The results of resting planar ECG-gated (99mTc-MIBI) imaging were compared with those of thallium-201 (Tl) re-injection after exercise-redistribution scintigraphy in 20 patients (19 men, 1 woman, mean age 53±10 years) with angiographically proven coronary artery disease. Eight normal subjects (seven men, one woman, mean age 50±8 years) constituted the control group. In these subjects, only resting 99mTc-MIBI imaging was performed. The standardized percent count increase from end-diastole to end-systole was calculated as an index of wall thickening in 13 segments for each study. Regional wall thickening index (WTI) and 99mTc-MIBI uptake were significantly different among segments classified as normal, reversible defects, irreversible defects with increased tracer uptake after re-injection (Re+) or irreversible defects with unchanged tracer uptake after re-injection (Re-) on Tl imaging. Furthermore, WTI and 99mTc-MIBI uptake were significantly higher in Re- segments with moderate reduction of Tl uptake (≥50% of peak activity) than in Re- segments with severe reduction of Tl uptake (<50% of peak activity). A significant relationship between WTI and the results of Tl scintigraphy was observed. The percentage of Re- segments with severe reduction of WTI was significantly higher compared to Re+ segments (64% vs 3%). Furthermore, compared with moderate Re- segments, a significantly higher percentage of severe Re- segments showed a severe reduction of WTI (86% vs 48%). Our data document a close relationship between 99mTc-MIBI regional wall thickening, myocardial perfusion and Tl uptake after re-injection. The results of this study suggest that regional WTI decreased significantly as myocardial perfusion decreased. In addition, regional wall thickening was preserved in segments with exercise-induced ischaemia and enhanced Tl uptake after re-injection. (orig.). With 4 figs., 3 tabs