Interpretation of myocardial perfusion SPECT with attenuation correction. Part 2

Abstract

Objective: to investigate the possibilities of a combined single photon emission computed tomography/computed tomography (SPECT/CT) system during myocardial perfusion studies and to examine the features of their interpretation.Subjects and methods. In April 2013 to April 2019, the Department of Radionuclide Diagnosis, National Medical Research Center of Cardiology, performed myocardial perfusion SPECT with attenuation correction (AC) in 3144 patients with various cardiovascular diseases. Based on the experience gained, the authors expanded and adjusted the principles of processing and interpreting the results of this study, which they had first set forth in 2014. Special emphasis is placed on the interpretation of apical and septal perfusion defects and diffuse perfusion irregularity, on the demonstration of the role of current reconstruction algorithms in obtaining highest-quality myocardial images, and on the assessment of self-potentialities of lowdose CT findings at myocardial SPECT/CT, as well as on proposals to standardize quantitative parameters for perfusion assessment at myocardial SPECT/CT.Results. AC affected in large measure the interpretation of myocardial perfusion SPECT in most cases. Apical perfusion defect appeared on AC images was observed in 50% of patients without established coronary heart disease and could be interpreted as a normal variant (apical thinning). The diffuse irregularity of perfusion radiopharmaceutical tracer accumulation in the application of the current reconstruction algorithms stood out in a separate pattern as a sign of microcirculatory disturbances. Low-dose CT data allow visualization of a severe thoracic abnormality at imaging and should be reflected in the conclusion. The perfusion study descriptions based on an analysis of AC and nAC images had a greater interoperator consistency than those based on an analysis of only nAC images (w = 0.915 and 0.809, respectively; p = 0.027). At the same time, the use of arithmetic means of the extent of transient ischemia (Reversibility Extent) is better consistent with visual analysis (= 0.08Ѓ}1.46%, p = 0.49).Conclusion. The use of AC and current iterative algorithms at myocardial perfusion SPECT should be part of a mandatory study protocol, since this affects to a large extent the diagnostic value of the technique. The borderline values of disturbed perfusion parameters at AC should be reconsidered.

Keywords

• single photon emission computed tomography/computed topography
• attenuation correction
• myocardium