[Myocardial scintigraphy with Tc-99m-MIBI for assessing the extent and severity of coronary disease: a comparison with thallium-201 and equilibrium angiocardioscintigraphy]

Abstract

Background: The aim of this study was to compare in the same population of patients affected by coronary artery disease (CAD), the accuracy in the assessment of CAD extent and severity achieved by myocardial scintigraphy, performed using Tc-99m-MIBI with two different imaging techniques (planar and single photon emission tomography--SPECT) and using TI-201 SPECT and by equilibrium radionuclide angiography (RNV).

Methods: We studied 20 patients (18 men and 2 women, age range 42-74) without prior myocardial infarction, but with effort angina. Seven had one-vessel and 13 multi-vessel disease; coronary artery stenosis was > or = 70% and < 80% in 18 arteries and > or = 80% in 19. After therapy withdrawal, all patients underwent (in different days, within 2 weeks): SPECT exercise TI-201 myocardial scintigraphy (early and redistribution images), planar and SPECT Tc-99m-MIBI myocardial scintigraphy (exercise and rest imaging 24 hours apart) and RNV (baseline and exercise studies).

Results: All methods were highly sensitive for the diagnosis of CAD: TI-201 SPECT 95%, Tc-99m-MIBI planar 95%, Tc-99m-MIBI SPECT 100%, RNV 100%. For the recognition of the involvement of more than one territory (multi-vessel disease) myocardial scintigraphy with Tc-99m-MIBI SPECT was the most sensitive (92%, p < 0.05 vs Tc-99m-MIBI planar and p < 0.01 vs RNV) and accurate (75%) method, while regional wall motion analysis with RNV showed the highest specificity (100%, p < 0.02 vs TI-201 SPECT, p < 0.05 vs Tc-99m-MIBI SPECT). For the recognition of the involved vessels Tc-99m-MIBI SPECT had the highest sensitivity (89%, p < 0.02 vs Tc-99m-MIBI planar, p < 0.002 vs RNV) and global accuracy (80%), while regional wall motion analysis with RNV had the highest specificity (96%, p < 0.02 vs Tc-99m-MIBI planar and SPECT, p < 0.001 vs TI-201 SPECT). The degree of obstruction (< 80% vs > or = 80%) significantly influenced the rate of positive RNV results (7/18 vs 14/19, p < 0.05), but not those of the different myocardial perfusion studies.

Conclusions: Our data show that clear differences among the tested methods are present with respect to the assessment of disease extent and severity. SPECT myocardial scintigraphy with Tc-99m-MIBI appears more accurate than the other methods for assessing the extent of CAD. RNV wall motion analysis shows a very good specificity for the recognition of multi-vessel CAD and for the detection of high grade obstructions. This encourages the efforts for studying, whenever possible, not only myocardial perfusion, but also ventricular function and regional wall motion. To this aim the collection of first-pass radionuclide angiocardiography at the moment of Tc-99m-MIBI injection could be particularly advantageous.