New protocol for contrast media reduction in atrial fibrillation ablation-planning CT with dual region of interest.

Introduction: Many patients with atrial fibrillation have impaired renal function, and therefore pre-operative CT for radiofrequency catheter ablation should minimize the use of contrast media. This study describes a dual-region-of-interest (D-ROI) protocol for the scanning of pulmonary veins and left atrium (PVs-LA) with less contrast media and optimized scan timing compared to the single-region-of-interest (S-ROI) protocol, without compromising image quality.

Methods: This study retrospectively included 100 patients who underwent PVs-LA CT between July 2019 and February 2022. The participants were divided into two groups: Those scanned using the S-ROI method (Group A, n = 50), and those scanned using the D-ROI method (Group B, n = 50). Descriptive statistical analysis of the contrast effect and scan timing was performed using quantitative and qualitative data collected from both groups of images.

Results: The contrast media dose was larger in group A than in group B (63.6 ± 10.1 mL vs. 45.6 ± 6.9 mL; p < 0.001). The CT values of the PVs-LA did not differ significantly between groups A and B [434.2 ± 77.0 Hounsfield units (HU) and 428.8 ± 77.2 HU, respectively; p = 0.73]. Two evaluators determined appropriate scan timing (when PVs-LA reached a relatively sufficient contrast effect for diagnosis) in 23 (46%) and 45 (90%) patients from groups A and B, respectively (p < 0.001).

Conclusions: Although the radiation dose is slightly increased compared with the S-ROI method, the D-ROI method provides improved scan timing and images with similar contrast enhancement while reducing the amount of contrast medium administered.

Implications For Practice: The novel D-ROI bolus tracking technique can reduce the contrast medium dose while optimizing scan timing.