[Evaluation of 320-row area detector computed tomography (ADCT) coronary angiography for patients with atrial fibrillation]

Computed tomography imaging using split-bolus contrast injection with volume scan of aortic root and heart for preoperative evaluation of transcatheter aortic valve implantation

The purpose of this study was to investigate using split-bolus contrast injection (SPBI) with volume scanning of the heart and aortic root with helical scanning of the access route, compared to single bolus contrast injection (SI) with variable helical pitch scanning (VHP) of the heart and aortic root and access route in a preoperative evaluation before transcatheter aortic valve implantation (TAVI). Thirty-five patients who underwent preoperative CT before TAVI using SPBI (contrast media: 24.5 mgI /kg/s, injected for 12 s for heart scan and then injected for 8 s for access route) were examined. Electrocardiogram (ECG) gated scans of the heart were performed by volume scan, after a period of time, non-gated helical scans of the aorto-iliac were performed (SPBI method). For comparison, 40 patients who had a single bolus injection (26.5 mg I/kg/s, injected for period of the scan time plus 3 s) and a VHP scan (SI method) before the SPBI method was performed were included in the study. The image qualities of the coronary arteries, aortic root, and access route (aorta-iliac), as well as radiation and iodine doses, were assessed. In visual assessment, image quality of coronary artery was significantly better with the SPBI method (grade; excellent: 57.1% in SPBI vs. 24.3% in SI, p = 0.03). There was no significant difference in image quality of the aortic root by visual assessment. The signal-to-noise (SNR) and contrast-to-noise ratio (CNR) of coronary and aortic root were not significantly different between the two methods. The access route showed significantly higher SNR (45.7 ± 11.5 vs. 34.3 ± 9.8, p < 0.001) and CNR (36.0 ± 9.7 vs. 28.0 ± 8.8, p < 0.001) for the SPBI method. The SPBI method compared to SI method reduced iodine dose by 10% and radiation dose by 45%. Preoperative CT imaging before TAVI using SPBI with volume scan is useful and can reduce iodine and radiation doses.

[Reconstruction of coronary 64-multidetector-row computed tomography angiography in patients with atrial fibrillation: delete short RR intervals using electorocardiogram]

BACKGROUND

The image qualities of coronary 64-multidetector-row computed tomography angiography (CCTA) in patients with atrial fibrillation (Afib) are often not enough. This study clarifies how to use electrocardiogram (ECG) -editing in Afib.

METHODS

We performed CCTA (Aquilion 64 with beam pitch: 0.125, 0.35 s/r) in 33 patients (M/F=24/9, age: 71±9 yr, mean heart rate: 71±12 bpm) with Afib. We injected 5 mg of verapamil into the vein when the mean HR was ≥80 bpm. First, we reconstructed images after deleting short RR (<800, 750, 700, 650, or 600). Second, we reconstructed images in 4 different methods: (1) end-systolic images with Phase Navi (automatically selecting an optimal phase) (ES-Navi), (2) Mid-diastolic images with Phase Navi (MD-Navi), (3) Mid-diastolic images reconstructed by the "R+absolute time method" [Edit-MD (R+)], and (4) Mid-diastolic images reconstructed by the "R-absolute time method" [Edit-MD (R-)]. We reconstructed 1 and 2 without ECG-editing, and 3 and 4 were reconstructed after ECG-editing without a data deficit. The quality of the images was classified into 3 ranks: no artifact (3), mild artifact (2), and severe artifact (1).

RESULTS

The image quality point of CCTA, reconstructed after deleting RR<750, was similar to RR<800, and RR<750 was even higher than that after deleting HR<600, 650, or 700. The mean image quality point of CCTA that was reconstructed by Edit-MD (R-) or Edit-MD (R+) was significantly higher than ES-Navi or MD-Navi.

CONCLUSION

The high image quality of CCTA could be reconstructed after deleting RR<750 in 76% or after deleting RR<800 in 70% of Afib. The reconstruction using Edit-MD (R-) or Edit-MD (R+) without a data deficit could provide a better quality CCTA than using PhaseNavi in Afib.