Abdominal CT with low radiation dose in severe obese patients: Application of wide-detector helical CT combined with adaptive statistical iterative reconstruction-V (ASIR-V)

Abstract

Objective To investigate the value of wide-detector helical CT combined with adaptive statistical iterative reconstruction-V (ASIR-V) in the low radiation dose CT examination of upper abdomen in obese patients. Methods In the first phantom experiment part, the optimal percentage of pre- and post-ASIR-V of abdominal scanning (120 kVp, NI=10 HU) were explored. The second human experiment was performed based on the phantom study, and our institutional review board approved this prospective study, each participant provided written informed consent. 87 obese patients (body mass index, BMI≥30 kg/m2) underwent contrast-enhanced abdominal CT scan were randomly divided into two scan protocols [protocol A: n=43, 120 kVp, detector coverage of 80 mm, 40% pre-ASIR-V (group A1) and combined with 60% post- ASIR-V (group A2) respectively; protocol B, n=44, 120 kVp, detector coverage of 40 mm, 40% ASIR (group B)]. Quantitative parameters [image noise and contrast-to-noise ratio (CNR)] and qualitative visual parameters (overall image quality as graded on a 5-point scale) were compared. Weighted effective dose (E) were assessed. Results The optimal percentage of pre- and post-ASIR-V of abdominal scanning were 40% and 60%, respectively. The effective radiation dose in protocol A [(4.55 ± 0.95) mSv] was decreased for 53% as compared with protocol B [(9.58 ± 2.04) mSv] (t=-14.773, P 0.05), and lower overall image quality scores(Z=-3.298--3.030, P<0.05) than group B. The overall image quality scores in group A were all greater than 3 point and met the clinical diagnostic level. Conclusions Compared with stand-detector helical CT in obese patients, the wide-detector helical CT combined with 40% pre-ASIR-V could reduce the radiation dose by 53%, and improve overall image quality by combining post- ASIR-V technique. Trial registration Chinese clinical trial registry, ChiCTR-DCD-15005932 Key words: Adaptive statistical iterative reconstruction-V; Wide-detector; Radiation dosage; Image quality; Obesity