Individualized protocol for radiation and contrast medium dose reduction in one-stop assessment for kidney transplantation patients

Abstract

Objective: To compare image quality, radiation, and contrast medium (CM) doses between individualized and conventional scan protocols in combined coronary CT angiography (CCTA) and iliac artery CTA for kidney transplantation patients.

Methods: 148 patients needing assessment for coronary and iliac arteries before kidney transplantation were prospectively enrolled and randomly divided into the conventional and individualized groups. All patients underwent one-stop combined scans on a 256-row CT scanner with automatic tube current modulation, 50 % pre-ASIR-V to control radiation dose. CCTA was performed first using one heartbeat axial scan mode with bolus tracking technique and iliac CTA was performed 3 s after CCTA using a spiral scan. The conventional group (n = 72) used the standard protocol: 100 kVp, 60 mL of 350 mgI/mL CM at 4.5 mL/s flow rate. The individualized group (n = 76) used a body-mass-index (BMI)-dependent protocol: kVp: 80 (BMI < 24) and 100 (BMI ≥ 24) and CM: 19 mgI/kg (BMI < 18); 21 mgI/kg (18 ≤ BMI < 24); and 22 mgI/kg (BMI ≥ 24). Image quality radiation and CM doses of the two groups were compared.

Results: There was no significant difference in patient demographic data. Compared with the conventional group, the individualized group reduced contrast flow rate (in mL/s) by 14.4 % (3.85 ± 0.72 vs. 4.5), contrast dose (in mL) by 35.8 % (38.53 ± 7.18 vs. 60) and radiation dose (in mSv) by 34.3 % (4.30 ± 1.73 vs. 6.54 ± 1.45). The individualized group had significantly higher subjective image quality score (P ＜ 0.05), lower noise (17.30 ± 4.97 HU vs. 19.13 ± 4.73 HU, P = 0.02) and higher signal-to-noise ratio (22.09 ± 7.41 vs. 19.55 ± 6.18, P = 0.03) for the three main vessels in CCTA compared with the conventional group. There were no differences in both subjective scores and objective measurements in iliac artery CTA between the two groups.

Conclusion: The individualized scanning protocol in the one-stop assessment of coronary and iliac arteries before kidney transplantation significantly reduces both radiation and CM doses while maintaining image quality in iliac artery CTA and providing better coronary artery images in CCTA.

Keywords: CT angiography; Kidney transplantation; Preoperative assessment; Scanning protocol.