Myocardial Coverage and Radiation Dose in Dynamic Myocardial Perfusion Imaging Using Third-Generation Dual-Source CT

Area of Science:

• Cardiovascular Imaging
• Computed Tomography
• Radiology

Background:

• Third-generation dual-source CT (3rd-DSCT) provides extended z-axis coverage (10.5 cm) for dynamic myocardial CT perfusion imaging (dynamic CTP).
• Concerns exist regarding potential increases in radiation dose and compromises in image quality or myocardial blood flow (MBF) quantification with the wider scan range, even when using lower tube voltage (70 kV).

Purpose of the Study:

• To compare image quality, estimated MBF, and radiation dose of dynamic CTP between 2nd-generation DSCT (2nd-DSCT) and 3rd-DSCT.
• To evaluate the suitability of 10.5-cm z-axis coverage for dynamic CTP.

Main Methods:

• Retrospective analysis of 107 patients undergoing dynamic CTP.
• Comparison between 2nd-DSCT at 80 kV (n=54) and 3rd-DSCT at 70 kV (n=53).
• Assessment of image quality (contrast-to-noise ratio), estimated MBF, radiation dose, and myocardial coverage.

Main Results:

• No significant difference in contrast-to-noise ratio between 3rd-DSCT and 2nd-DSCT (37.4 ± 11.4 vs. 35.5 ± 11.2).
• Lower effective radiation dose with 3rd-DSCT (3.97 ± 0.92 mSv) compared to 2nd-DSCT (5.49 ± 1.36 mSv).
• Significantly less incomplete coverage with 3rd-DSCT (1.9%) versus 2nd-DSCT (56%).
• Comparable MBF in both non-ischemic and ischemic myocardium between the two generations.

Conclusions:

• Utilizing 70 kV tube voltage with 3rd-DSCT effectively balances increased z-axis coverage without compromising image quality or MBF quantification.
• A 10.5-cm z-axis coverage is adequate for complete left ventricular myocardial coverage in most patients during dynamic CTP.