APSCM + iterative reconstruction improve quality of coronary CTA

Combining automatic tube potential selection with tube current modulation (APSCM) and iterative reconstruction significantly improves objective image quality and reduces radiation dose at coronary CT angiography (CTA), according to a study published in August in Radiology.

The study showed the potential benefits of using APSCM over a body mass index (BMI)-based protocol, the most commonly used technique that adapts kilovolt and tube current-time produce according to the patient’s BMI, according to Young Joo Suh, MD, and colleagues from Yonsei University College of Medicine, Seoul, Korea.

Tube potential modulation with APSCM has recently been developed as a technique that automatically selects appropriate kilovolt and milliampere second settings for each patient in order to maintain a set contrast-to-noise ratio (CNR) selected by the user, explained the authors.

Suh and colleagues devised a study to analyze the effect of APSCM on image quality, diagnostic accuracy and radiation dose. They also wanted to determine the effect of sinogram-affirmed iterative reconstruction (SAFIRE) compared with traditional filtered back projection (FBP).

The retrospective analysis included images from 185 patients who underwent CTA with a BMI-based protocol and 197 who underwent an APSCM protocol with FBP and an APSCM protocol with SAFIRE. A subgroup of 51 patients was used to compare diagnostic performance with that of conventional coronary angiography.

“The APSCM group with SAFIRE had a significant reduction in image noise and a significant increase in CT number, contrast enhancement, signal-to-noise ratio, and contrast-to-noise ratio compared with the APSCM group with FBP and the BMI-based group,” wrote the authors. The APSCM group with SAFIRE resulted in a 29 percent decrease in image noise and a 41 percent increase in signal-to-noise ratio (SNR) and CNR compared with the APSCM group that used FBP.

Compared with a BMI-based protocol with FBP, the technique of combining APSCM and SAFIRE led to a 9 percent decrease in image noise and a 21 percent increase in CNR and SNR.

Suh and colleagues noted that while objective measures of image quality were improved by combining tube potential modulation with iterative reconstruction, diagnostic accuracy was similar between the three study groups.