Rationale and objectives
We sought to explore the feasibility and diagnostic performance of dual-energy computed tomography (DECT) versus single-energy computed tomography (SECT) for the evaluation of myocardial perfusion in patients with intermediate to high likelihood of coronary artery disease.
Materials and Methods
The present prospective study involved patients with known or suspected coronary artery disease referred for myocardial perfusion imaging by single-photon emission computed tomography. Forty patients were included in the study protocol and scanned using DECT imaging ( n = 20) or SECT imaging ( n = 20). The same pharmacologic stress was used for DECT, SECT, and single-photon emission computed tomography scans.
Results
A total of 1360 left ventricular segments were evaluated by DECT and SECT. The contrast-to-noise ratio was similar between groups (DECT 8.8 ± 2.9 vs. SECT 7.7 ± 4.2; P = .22). The diagnostic performance of DECT was greater than that of SECT in identifying perfusion defects (area under the receiver operating characteristic curve of DECT 0.90 [0.86–0.94] vs SECT 0.80 [0.76–0.84]; P = .0004) and remained unaffected when including only segments affected by beam-hardening artifacts (area under the receiver operating characteristic curve = DECT 0.90 [0.84–0.96) vs. SECT 0.77 [0.69–0.84]; P = .007).
Conclusions
Our results suggest that myocardial perfusion by DECT imaging is feasible and might have improved diagnostic performance compared to SECT imaging for the assessment of myocardial CT perfusion. Furthermore, the diagnostic performance of DECT remained unaffected by the presence of beam-hardening artifacts.
Until recently, coronary computed tomography angiography (CCTA) was limited to the anatomic assessment of coronary obstructions in patients with low to intermediate likelihood of coronary artery disease (CAD), whereas the functional significance of coronary stenoses remained outside its scope. Several studies have demonstrated the ability of CCTA to perform myocardium perfusion studies by using stress vasodilator agents . However, the clinical use of stress myocardium computed tomography (CT) perfusion is somewhat limited, mostly by technical issues including beam-hardening artifacts (BHAs), which are originated by the polychromatic nature of x-rays and the energy dependency of x-ray attenuation, and are related to a considerable myocardial signal density (SD) drop at regions in close proximity to highly attenuated structures, thus resembling perfusion defects .
With the advent of dual-energy computed tomography (DECT) imaging, BHAs could be reduced with the generation of synthesized monochromatic image reconstruction . We therefore sought to explore the feasibility and diagnostic performance of DECT versus single-energy computed tomography (SECT) for the evaluation of myocardial perfusion defects assessed by single-photon emission computed tomography (SPECT) in patients with intermediate to high likelihood of CAD. Furthermore, we sought to compare the diagnostic performance of DECT versus SECT among myocardial regions with high prevalence of BHAs.
Methods
Study Population
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CT Perfusion Acquisition
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Dual-Energy CT
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Single-Energy CT
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SPECT Myocardial Perfusion Imaging
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CT Perfusion Analysis
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Statistical Analysis
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Results
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Image Quality and Effective Radiation Dose
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Table 1
Effective Radiation Doses
Scan Radiation Dose (mSV)P Value SPECT vs. DECT SECT SPECT DECT SECT Stress 4.3 ± 1.0 7.1 ± 2.6 ∗ Rest 3.2 ± 0.4 2.8 ± 2.1 † Total 7.4 ± 1.1 9.9 ± 3.8 ‡ 8.8 ± 2.0 0.06 0.41
DECT, dual-energy computed tomography; SECT, single-energy computed tomography; SPECT, single-photon emission computed tomography.
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Diagnostic Performance of DECT Versus SECT
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Table 2
Diagnostic Performance of SECT and DECT
Diagnostic performance SECT DECT SECT BHA DECT BHA Sensitivity (%) 70.3 (63.9–76.1) 82.8 (75.1–88.9) 69.1 (56.6–79.5) 86.6 (71.9–94.3) Specificity (%) 90.7 (87.6–93.2) 96.7 (94.9–98.1) 84.1 (76.5–89.7) 93.6 (88.2–96.7) Positive predictive value (%) 79.3 (73.0–84.7) 85.5 (78.0–91.2) 69.1 (56.6–79.5) 79.2 (64.6–89.0) Negative predictive value (%) 85.7 (82.2–88.7) 96.0 (94.1–97.5) 84.1 (76.5–89.7) 96.1 (91.2–98.4) Positive likelihood ratio 7.5 (5.6–10.2) 25.4 (16.1–40.2) 4.3 (2.8–6.6) 13.5 (7.3–24.8) Negative likelihood ratio 0.33 (0.27–0.40) 0.18 (0.12–0.25) 0.37 (0.26–0.52) 0.15 (0.07–0.31) Diagnostic odds ratio 23.1 (14.8–36.2) 142.9 (70.9–291.7) 11.8 (5.9–23.7) 92.5 (31.6–270.4) Area under the curve (ROC) 0.80 (0.76–0.84) 0.90 (0.86–0.94) 0.77 (0.69–0.84) 0.90 (0.84–0.96)
BHA, beam-hardening artifact; DECT, dual-energy computed tomography; ROC, receiver operating characteristic; SECT, single-energy computed tomography.
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Analysis Including Segments Affected by BHAs
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Discussion
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Limitations
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Conclusions
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