Use of a new myocardial centroid for measurement of regional myocardial dysfunction by electron beam computed tomography - Comparison with technetium-99m sestamibi infarct size quantification

RATIONALE AND OBJECTIVES. The study compared the performance of conventiona l endocardial and epicardial centroid algorithms with the new "myocardial" centroid algorithm in patients with anterior myocardial infarction, "Floati ng" endocardial or epicardial centroid algorithms, commonly used in tomogra phic imaging methods to assess regional motion, may misrepresent left ventr icular regional myocardial function in the presence of markedly asymmetric left ventricular contraction. METHODS. A new centroid algorithm based on regional myocardial mass distrib ution was tested in 29 patients with a first anterior myocardial infarction and was compared with conventional centroid algorithms. Direct comparisons in 50 equal sectors at one midventricular level per patient were performed between electron beam computed tomography and technetium-99m sestamibi sin gle-photon emission computed tomography, The thresholds of regional myocard ial function used to define infarction were varied for regional ejection fr action from 20% to 40% and for regional wall thickening from 0 to 4 mm, Reg ression and Bland-Altman analysis were used to compare infarct size by regi onal myocardial function with infarct size by sestamibi single-photon emiss ion computed tomography, RESULTS, The new myocardial centroid showed the least shift toward infarcte d myocardium from diastole to systole and had the highest amplitudes of the measurement curves for regional ejection fraction and regional wall thicke ning. The optimal regional myocardial function thresholds for each centroid algorithm for regional ejection fraction were endocardial, 30% (R = 0.62; mean difference to sestamibi, -0.5% +/- 22.1% tomographic infarct size poin ts); epicardial, 30% (R = 0.79; mean difference, 2.2% +/- 13.1% tomographic infarct size points); and new myocardial, 25% (R = 0.88; mean difference, -0.6% +/- 9.5% tomographic infarct size points). The optimal thresholds for regional wall thickening were endocardial, 1 mm (R = 0.70 mean difference, -2.2% +/- 14.3% tomographic infarct size points); epicardial, 1 mm (R = 0. 78; mean difference, -4.6% +/- 12.7% tomographic infarct size points); and new myocardial, 2 mm (R = 0.71; mean difference, 2.1% +/- 14.1% tomographic infarct size points). The best agreement (R = 0.88) between electron beam computed tomography infarct size and sestamibi single-photon emission compu ted tomography infarct size was achieved with regional ejection fraction an d the new myocardial centroid algorithm. Conclusions, In asymmetrically contracting left ventricles, the new myocard ial centroid algorithm is superior to conventional methods for tomographic analysis of regional myocardial function.