Quantitative myocardial perfusion imaging using rapid kVp switch dual-energy CT: preliminary experience.

BACKGROUND: Quantitative myocardial CT perfusion (CTP) is susceptible to beam-hardening (BH) artifact from conventional single-energy (kVp) CT (SECT) scanning, which can mimic perfusion deficits.

OBJECTIVE: We evaluated the minimization of BH artifact with dual-energy (kVp) CT (DECT) generated monochromatic CT images to improve perfusion estimates.

METHODS: We investigated the performance of DECT with a scanner capable of rapid kVp switching with respect to (1) BH artifact in a myocardium phantom model comparing SECT with image-based DECT and projection-based DECT, (2) optimal imaging parameters for measuring iodine concentration at high contrast-to-noise ratio in a tissue characterization phantom model, and (3) the feasibility of a dynamic time-resolved scan protocol with the projection-based DECT technique to measure myocardial perfusion in normal (nonischemic) porcine.

RESULTS: In a myocardium phantom model, projection-based DECT 70 keV was better able to minimize the difference in the attenuation of the myocardium (19.9 HU) between having and not having contrast in the heart chambers in comparison to SECT using 80 kVp (30.4 HU) or 140 kVp ( 23.3 HU) and image-based DECT 70 keV (27.5 HU). Further, projection-based DECT 70 keV achieved the highest contrast-to-noise ratio (3.0), which exceeded that from imaged-based DECT 70 keV (2.0), 140 kVp SECT (1.3), and 80 kVp SECT (2.9). In 5 normal pigs, projection-based DECT at 70 keV provided a more uniform perfusion estimate than SECT.

CONCLUSION: By effectively reducing BH artifact, projection-based DECT may permit improved quantitative myocardial CTP compared with the conventional SECT technique.