Technical aspects of myocardial planar imaging with technetium-99m sestamibi

• Published in: The American journal of cardiology Vol. 66; no. 13; pp. E16 - E22
• Main Authors: Smith, William H., Watson, Denny D.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY Elsevier Inc 16.10.1990; Elsevier
• Subjects: Biological and medical sciences; Cardiovascular system; Heart - diagnostic imaging; Humans; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Nitriles; Organotechnetium Compounds; Radionuclide investigations; Subtraction Technique; Technetium Tc 99m Sestamibi; Technology, Radiologic; Tomography, Emission-Computed - standards
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/0002-9149(90)90607-3

Fundamental quantitative planar imaging techniques, evolved over the years, have been adapted to maximize the efficiency and clinical effectiveness of technetium-99m (Tc-99m) sestamibi imaging. To ensure reproducible image interpretation, the Society for Motion Picture and Television Engineers test pattern is used to obtain the necessary standardization of video and hard copy images. A standardized intensity scale intuitively relates count density to perceived brightness. Data are accumulated via standard 16-frame multiple gated acquisition and can be viewed in cine mode to assess wall motion. The images are then automatically summed for quantitative analysis of myocardial perfusion. Excessive extracardiac Tc-99m activity is automatically suppressed by the computer program to prevent suboptimal display of the heart. Due to the difference in heart background ratio and shape of the extracardiac background between resting and exercise Tc-99m sestamibi images, a modified interpolative background subtraction algorithm was developed. Image registration is necessary for accurate comparison of the rest and exercise images to detect redistribution. This is automatically accomplished by adjusting the position of the background-subtracted and centered images so as to maximize the cross-correlation coefficient. Profiles are generated to sample the myocardial count distribution and can be compared to a normal database, subject to confirmation by a competent interpreter. Rest redistribution is defined by a change in the myocardial distribution of Tc-99m sestamibi between exercise and rest images. Flashback display is used to identify subtle regions of redistribution that often signify residual viability within an infarct zone. In this technique, which maintains standard anatomic images for the interpreter, exercise and rest background-corrected images are brought into registration and each scaled to its maximum count so that alternate images can be flashed on the screen in the same position. Redistribution in a myocardial segment will appear as a sudden shift of intensity relative to the remainder of the image during flashback.