Myocardial perfusion imaging and infarct characterization using multidetector cardiac computed tomography

Comparison of myocardial perfusion evaluation with single versus dual-energy CT and effect of beam-hardening artifacts

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.

Beam hardening artifact reduction using dual energy computed tomography: implications for myocardial perfusion studies

BACKGROUND

Myocardial computed tomography perfusion (CTP) using conventional single energy (SE) imaging is influenced by the presence of beam hardening artifacts (BHA), occasionally resembling perfusion defects and commonly observed at the left ventricular posterobasal wall (PB). We therefore sought to explore the ability of dual energy (DE) CTP to attenuate the presence of BHA.

METHODS

Consecutive patients without history of coronary artery disease who were referred for computed tomography coronary angiography (CTCA) due to atypical chest pain and a normal stress-rest SPECT and had absence or mild coronary atherosclerosis constituted the study population. The study group was acquired using DE and the control group using SE imaging.

RESULTS

Demographical characteristics were similar between groups, as well as the heart rate and the effective radiation dose. Myocardial signal density (SD) levels were evaluated in 280 basal segments among the DE group (140 PB segments for each energy level from 40 to 100 keV; and 140 reference segments), and in 40 basal segments (at the same locations) among the SE group. Among the DE group, myocardial SD levels and myocardial SD ratio evaluated at the reference segment were higher at low energy levels, with significantly lower SD levels at increasing energy levels. Myocardial signal-to-noise ratio was not significantly influenced by the energy level applied, although 70 keV was identified as the energy level with the best overall signal-to-noise ratio. Significant differences were identified between the PB segment and the reference segment among the lower energy levels, whereas at ≥70 keV myocardial SD levels were similar. Compared to DE reconstructions at the best energy level (70 keV), SE acquisitions showed no significant differences overall regarding myocardial SD levels among the reference segments.

CONCLUSIONS

BHA that influence the assessment of myocardial perfusion can be attenuated using DE at 70 keV or higher.