Hassan Mohy-Ud-Din1,2, Nabil E Boutagy3, John C Stendahl3, Zhen W Zhuang3, Albert J Sinusas4,3, Chi Liu5. 1. Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA. hassanmohyuddin@skm.org.pk. 2. Shaukat Khanum Memorial Cancer Hospital and Research Center, 7-A, Block R-3, Johar Town, Lahore, 54000, Pakistan. hassanmohyuddin@skm.org.pk. 3. Section of Cardiovascular Medicine, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA. 4. Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA. 5. Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA. chi.liu@yale.edu.
Abstract
BACKGROUND: Currently, there is no established non-invasive imaging approach to directly evaluate myocardial microcirculatory function in order to diagnose microvascular disease independent of co-existing epicardial disease. In this work, we developed a methodological framework for quantification of intramyocardial blood volume (IMBV) as a novel index of microcirculatory function with SPECT/CT imaging of 99mTc-labeled red blood cells (RBCs). METHODS: Dual-gated myocardial SPECT/CT equilibrium imaging of 99mTc-RBCs was performed on twelve canines under resting conditions. Five correction schemes were studied: cardiac gating with no other corrections (CG), CG with attenuation correction (CG + AC), CG + AC with scatter correction (CG + AC + SC), dual cardiorespiratory gating with AC + SC (DG + AC + SC), and DG + AC + SC with partial volume correction (DG + AC + SC + PVC). Quantification of IMBV using each approach was evaluated in comparison to those obtained from all corrections. The in vivo SPECT estimates of IMBV values were validated against those obtained from ex vivo microCT imaging of the casted hearts. RESULTS: The estimated IMBV with all corrections was 0.15 ± 0.03 for the end-diastolic phase and 0.11 ± 0.03 for the end-systolic phase. The cycle-dependent change in IMBV (ΔIMBV) with all corrections was 23.9 ± 8.6%. Schemes that applied no correction or partial correction resulted in significant over-estimation of IMBV and significant under-underestimation of ΔIMBV. Estimates of IMBV and ΔIMBV using all corrections were consistent with values reported in the literature using invasive techniques. In vivo SPECT estimates of IMBV strongly correlated (R2 ≥ 0.70) with ex vivo measures for the various correction schemes, while the fully corrected scheme yielded the smallest bias. CONCLUSIONS: Non-invasive quantification of IMBV is feasible using 99mTc-RBCs SPECT/CT imaging, however, requires full compensation of physical degradation factors.
BACKGROUND: Currently, there is no established non-invasive imaging approach to directly evaluate myocardial microcirculatory function in order to diagnose microvascular disease independent of co-existing epicardial disease. In this work, we developed a methodological framework for quantification of intramyocardial blood volume (IMBV) as a novel index of microcirculatory function with SPECT/CT imaging of 99mTc-labeled red blood cells (RBCs). METHODS: Dual-gated myocardial SPECT/CT equilibrium imaging of 99mTc-RBCs was performed on twelve canines under resting conditions. Five correction schemes were studied: cardiac gating with no other corrections (CG), CG with attenuation correction (CG + AC), CG + AC with scatter correction (CG + AC + SC), dual cardiorespiratory gating with AC + SC (DG + AC + SC), and DG + AC + SC with partial volume correction (DG + AC + SC + PVC). Quantification of IMBV using each approach was evaluated in comparison to those obtained from all corrections. The in vivo SPECT estimates of IMBV values were validated against those obtained from ex vivo microCT imaging of the casted hearts. RESULTS: The estimated IMBV with all corrections was 0.15 ± 0.03 for the end-diastolic phase and 0.11 ± 0.03 for the end-systolic phase. The cycle-dependent change in IMBV (ΔIMBV) with all corrections was 23.9 ± 8.6%. Schemes that applied no correction or partial correction resulted in significant over-estimation of IMBV and significant under-underestimation of ΔIMBV. Estimates of IMBV and ΔIMBV using all corrections were consistent with values reported in the literature using invasive techniques. In vivo SPECT estimates of IMBV strongly correlated (R2 ≥ 0.70) with ex vivo measures for the various correction schemes, while the fully corrected scheme yielded the smallest bias. CONCLUSIONS: Non-invasive quantification of IMBV is feasible using 99mTc-RBCs SPECT/CT imaging, however, requires full compensation of physical degradation factors.
Authors: Jing Wu; Nabil E Boutagy; Zhengxin Cai; Shu-Fei Lin; Ming-Qiang Zheng; Attila Feher; John C Stendahl; Michael Kapinos; Jean-Dominique Gallezot; Hui Liu; Tim Mulnix; Wenjie Zhang; Marcel Lindemann; Jo-Ku Teng; Edward J Miller; Yiyun Huang; Richard E Carson; Albert J Sinusas; Chi Liu Journal: J Nucl Cardiol Date: 2020-05-15 Impact factor: 5.952