What is the value of motion and thickening in gated myocardial perfusion SPECT?

Abstract

Myocardial perfusion SPECT imaging (MPI) is a stress imaging modality, widely used in the detection and evaluation of coronary artery disease (CAD). This method is unique in providing simultaneous bi-modal functional imaging of relative myocardial perfusion and left ventricular (LV) function.1 While perfusion images identify regions with relative hypoperfusion, gated SPECT allows assessment of global and regional LV function. The added prognostic information gained by global LV function to myocardial perfusion findings has been extensively shown.2,3 However, accurate regional assessment of contractile function is also of great importance, since it could enhance the detection of CAD, 4 and provide additional prognostic information in predicting cardiac events. 5,6 Similar to myocardial perfusion, regional motion and thickening can be assessed using semi-quantitative visual methods, based on segmental scoring. While motion score simply reflects the extent of inward shift of the ventricular wall, thickening is assessed as systolic brightening of the myocardium occurring due to the partial volume effect. This systolic apparent increase in count density occurs since myocardial thickness is commonly in the range up to 2 cm, less than twice the full width at half maximum of the point spread function of conventional gamma cameras with intrinsic spatial resolution of *1 cm.7 Visual assessment of regional LV contractile function is expert dependent, and suffers from limited reproducibility with high inter-and intraobserver variability. 8 Therefore, several methods have been developed and validated, which automatically quantify motion and thickening, and provide useful and reproducible assessment of regional function.9,10 Whether visually or automatically assessed, regional motion and thickening have been shown as important adjunctive parameters to perfusion in the diagnosis of CAD.In the current issue of the Journal of Nuclear Cardiology, Yang et al. used resting gated SPECT MPI to demonstrate the relationship between myocardial thickening and LV remodeling among patients with history of myocardial infarction (MI). The 92 patients included in the analysis were divided into subacute MI (3-6 months before nuclear testing, n = 54) and old MI ([6 months before nuclear testing, n = 38) subgroups. In addition, all patients underwent FDG-PET imaging to identify myocardial viability as metabolic perfusion mismatch, and a scar score was calculated. LV remodeling was defined as end-diastolic volume index [62.53 ml/m 2 , derived as mean value ?2 standard deviations from gated SPECT of another 95 patients who had normal SPECT MPI and no evidence of CAD. Compared to patients with subacute MI, those with old MI had larger LV volume and worse cardiac function, larger perfusion deficit, and higher summed thickening score (STS). Interestingly, of all the demographic, clinical, perfusion, and metabolic imaging parameters evaluated, only the STS and the % of segments with reduced thickening among segments with normal perfusion were independ...

Integrating subvolume dose and myocardial perfusion imaging parameters to assess the impact of radiation therapy on heart function in breast cancer patients: A comparative analysis between left‐ and right‐sided breast cancer

“…10 Single photon emission computed tomography (SPECT) with myocardial perfusion imaging (MPI) and semi-quantitative analysis are highly effective tools for the early detection of myocardial perfusion defects, [11][12][13] and can also provide multiple indicators of cardiac function for evaluating the severity of heart disease. [14][15][16][17] However, there is currently a lack of research that analyzes the correlation between the radiation dose received by the left ventricular 20 regions and the parameters of MPI including end-diastolic volume (EDV), end-systolic volume (ESV), wall motion (WM), and wall thickening (WT) in breast cancer patients after radiation therapy. Therefore, the aim of this study was to utilize an innovative method of integrating the 20 subvolume dose of left ventricle and the MPI parameters of the 20 subvolumes in patients with left-or right-sided breast cancer after radiation therapy.…”