Quantitative Analysis of Myocardial Perfusion SPECT Anatomically Guided by Coregistered 64-Slice Coronary CT Angiography

Abstract

Aim Sequential testing by coronary computed tomography angiography (CTA) and myocardial perfusion SPECT (MPS) obtained on standalone scanners may be needed to diagnose coronary artery disease (CAD) in equivocal cases. We have developed an automated technique for MPS-CTA registration and demonstrate its utility for improved MPS quantification by guiding the co-registered physiological (MPS) with anatomical CTA information. Methods Automated registration of MPS left ventricular (LV) surfaces with CTA coronary trees was accomplished by iterative minimization of voxel differences between pre-segmented CTA volumes and “motion-frozen” MPS data. Studies of 35 sequential patients (26 males), mean age 67±12 years with 64-slice coronary CTA, MPS and with available results of the invasive coronary angiography performed within 3 months were retrospectively analyzed. 3D coronary vessels and CTA slices were extracted and fused with quantitative MPS results mapped on LV surfaces and MPS coronary regions. Automatically co-registered CTA images and extracted trees were used to correct the MPS contours and to adjust the standard vascular region definitions for MPS quantification. Results Automated co-registration of MPS and coronary CTA had the success rate of 96% as assessed visually; the average errors were 4.3±3.3 mm in translation and 1.5±2.6 deg in rotation on stress and 4.2±3.1 mm in translation and 1.7±3.2 deg in rotation on rest. MPS vascular region definition was adjusted in 17 studies and LV contours were adjusted in 11 studies using co-registered CTA images as a guide. CTA-guided MP analysis resulted in improved area under the receiver operator characteristics (ROC) curves for the detection of RCA and LCX lesions as compared to standard MPS analysis 0.84±0.08 vs. 0.70±0.11 for LCX (p = 0.03) and 0.92±0.05 vs. 0.75±0.09 (p=0.02) for RCA. Conclusions Software image co-registration of standalone coronary CTA and MPS obtained on separate scanners can be performed rapidly and automatically allowing CTA-guided contour and vascular territory adjustment on MPS for improved quantitative MPS analysis.

Hybrid Imaging Using Quantitative H215O PET and CT-Based Coronary Angiography for the Detection of Coronary Artery Disease

“…Fourth, although care was taken to match individual coronary anatomy to perfusion territories in the evaluation of the PET/CTCA scan, software to generate fusion images of CTCA and PET was not commercially available from the manufacturer of our installed system. Some studies have demonstrated that fused hybrid imaging as compared with side-by-side analysis may slightly improve diagnostic accuracy (34)(35)(36). Finally, parametric perfusion images were generated by different software packages developed in-house in both studies (12,37).…”

Cardiac SPECT/CT Imaging: CT Attenuation Correction and SPECT/CT Hybrid Imaging

“…These reported that the use of cardiac SPECT/CT hybrid imaging decreased the indeterminate diagnostic rate and consequently increased the conclusive diagnostic rate compared to side-by-side interpretations in patients with CAD. These patients, who are often found to have multivessel disease (MVD), moderate coronary stenoses, or branch lesions, also often see the greatest diagnostic improvement in regard to these findings via cardiac SPECT/CT fusion imaging (Figure 4 and 5) [75][76][77]. Hybrid cardiac imaging can facilitate the detection of hemodynamically significant coronary artery stenosis, leading to appropriate choices of therapeutic methods.…”

Multimodality cardiac imaging

“…13 Traditionally, LCX and RCA are subject to more variable patterns of coronary artery anatomy than the left anterior descending artery, which explains the particular value of hybrid imaging in these territories.…”

“…12 A recent study implementing motion-frozen SPECT data and CTA-guided SPECT contour and territory adjustments, found that the improved diagnostic value of hybrid imaging was mainly driven by higher diagnostic indices in the left circumflex (LCX) and right coronary artery (RCA) territories. 13 Traditionally, LCX and RCA are subject to more variable patterns of coronary artery anatomy than the left anterior descending artery, which explains the particular value of hybrid imaging in these territories.…”

“…Additionally, the increased availability of dedicated fusion software packages for three-dimensional coregistration of CTA and MPI have facilitated the use of hybrid imaging in clinical practice. 8,9 The feasibility and clinical robustness of noninvasive hybrid imaging was first documented by Namdar and coworkers in a clinical study involving fusion of 13 N-ammonia positron emission tomography (PET) with 4-slice CTA in 25 patients with CAD. 10 The hybrid PET/CTA images allowed to identify flow-limiting coronary lesions which required a revascularization procedure (as defined by invasive coronary angiography and PET) with a sensitivity, specificity, positive, and negative predictive value of 90%, 98%, 82%, and 99%, respectively.…”