Evaluation of 99mTc-myocardial Perfusion SPECT Attenuation Correction by Hybrid SPECT/CT-Examination by Quantitative Analysis-

Abstract

A non-uniform attenuation correction is necessary for the myocardial perfusion image (MPI) SPECT that is one of the images of the trunk. Simultaneous non-uniform attenuation correction during the process of SPECT reconstruction was enabled by developing hybrid SPECT/CT. Image acquisition of 99m Tc MPI with hybrid SPECT/CT was performed in a phantom study and clinical cases We evaluated the effect of non-uniform attenuation correction by Filtered Back Projection (FBP) or Ordered Subsets-Expectation Maximization (OS-EM) using visual analysis and quantitative analysis with a 17-segment model. The phantom study and the clinical cases differed somewhat as follows In the phantom study, the count increased significantly with non-uniform attenuation correction in visual analysis and quantitative analysis. In the clinical cases, non-uniform attenuation correction increased the quantitative count in the basal and middle layer of the heart, and visual uniformity of the whole heart improved. However, the visual and quantitative count in the apex decreased with non-uniform attenuation correction. As a result, diagnostic performance for coronary heart disease is expected to be improved by this new technique using hybrid SPECT/CT.

Cause of apical thinning on attenuation-corrected myocardial perfusion SPECT

“…Attenuation correction, however, induces an artifactual myocardial perfusion defect at the apex, which is called "apical thinning" [11][12][13][14]. Subsequently, this phenomenon induces falsepositive hypoperfusion in normal perfusion and reduces specificity for the detection of CAD.…”

Validation of prone myocardial perfusion SPECT with a variable-focus collimator versus supine myocardial perfusion SPECT with or without computed tomography-derived attenuation correction

“…Indeed, a phantom study on conventional SPECT with a parallel-hole collimator has shown that CTAC can introduce artificial apical defects [15]. Furthermore, in a study in human using technetium-99m tetrofosmin MPS with a parallel-hole collimator, myocardial tracer accumulation in the apex was lower in supine images acquired with CTAC than in those acquired without CTAC [16].…”