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Published on: August 28, 2018
Platform-specific impact of CT attenuation correction on CZT myocardial perfusion SPECT: per-vessel detection of
Yoshimitsu Honda1, Yoshimitsu Fukushima2, Kenji Yodogawa3
1Department of Radiology, Nippon Medical School, Tokyo, Japan.
Insights
CT attenuation correction (CTAC) significantly improves the detection of coronary artery disease (CAD) on 19-pinhole CZT SPECT imaging. This method enhances sensitivity for identifying obstructive CAD, particularly in the LCX and RCA territories.
Area of Science:
- Nuclear Medicine
- Cardiovascular Imaging
- Medical Physics
Background:
- Myocardial perfusion SPECT imaging is crucial for diagnosing coronary artery disease (CAD).
- Attenuation artifacts can affect image quality and diagnostic accuracy in SPECT.
- CT attenuation correction (CTAC) is a technique used to reduce these artifacts.
Purpose of the Study:
- To evaluate the impact of CT attenuation correction (CTAC) on the per-vessel detection of obstructive CAD.
- To assess the diagnostic performance of CTAC on a 19-pinhole CZT SPECT system compared to non-attenuation-corrected (NAC) imaging.
Main Methods:
- Retrospective analysis of 48 patients with confirmed CAD undergoing rest-stress ⁹⁹ᵐTc-tetrofosmin CZT SPECT.
- SPECT images were reconstructed with and without CTAC.
- Perfusion defects were quantified and compared between NAC and CTAC reconstructions.
- Reference standard was ≥70% diameter stenosis on coronary CT angiography or invasive angiography.
Main Results:
- CTAC significantly reduced global rest defect rates and increased reversible defect rates (5.9% vs. 1.5%).
- CTAC improved the discrimination of territories with obstructive stenosis (AUC 0.717 vs. 0.614).
- Sensitivity for detecting obstructive CAD increased from 52.8% to 75.5% with CTAC, with a modest decrease in specificity (68.9% to 64.4%).
- The greatest improvement was observed in the LCX and RCA territories.
Conclusions:
- CTAC enhances the per-vessel detection of obstructive CAD on a 19-pinhole CZT SPECT platform.
- The benefits of CTAC are primarily sensitivity-driven, offering a significant improvement in identifying significant coronary artery stenosis.
- CTAC provides a valuable tool for improving diagnostic accuracy in myocardial perfusion imaging, especially in specific coronary territories.
Abstract:
Attenuation artifacts on myocardial perfusion SPECT differ across camera geometries. This study evaluated whether CT attenuation correction (CTAC) improves per-vessel detection of obstructive coronary artery disease (CAD) on a stationary 19-pinhole CZT system. Rest-stress ⁹⁹ᵐTc-tetrofosmin CZT SPECT studies from 48 patients with angiographically confirmed CAD (185 vessels) were retrospectively reconstructed with and without CTAC. The reference standard was ≥ 70% diameter stenosis on coronary CT angiography or invasive angiography, with no perfusion input. Disease-negative participants were excluded by design. Perfusion was quantified as the percent defect averaged within each coronary territory, assigned per patient on hybrid SPECT/CT fusion images. Per-vessel discrimination of the reversible (stress - rest) defect rate was compared between reconstructions. Compared with non-attenuation-corrected (NAC) reconstructions, CTAC lowered the global rest defect rate (P < 0.0001) and raised the reversible defect rate (median 5.9% vs. 1.5%; P < 0.0001). The reversible defect rate discriminated territories subtended by obstructive stenosis better with CTAC than with NAC (AUC 0.717 vs. 0.614; ΔAUC 0.103; DeLong P = 0.0164; bootstrap P = 0.010; within-patient permutation P = 0.0474). At the Youden point, sensitivity rose to 75.5% from 52.8%, with specificity 64.4% versus 68.9%. The gain was greatest in the LCX (0.803 vs. 0.658; P = 0.043) and RCA territories. On this 19-pinhole CZT platform, CTAC improves per-vessel discrimination of obstructive CAD, most prominently in the LCX and RCA territories. The benefit is sensitivity-led, opposite to the specificity-led gain reported on Anger cameras, at a modest cost in specificity.
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