A feasibility study on “Tri-Low” technology in combination with iterative model reconstruction (IMR) algorithm in CT angiography(CTA) of the head-and-neck vessels / 中华放射医学与防护杂志

ABSTRACT

Objective To evaluate the feasibility of low-tube-voltage, low injection rate, low contrast agent dosage in combination with iterative model reconstruction ( IMR) algorithm in CT angiography ( CTA) of the head-and-neck vessels .Methods Sixty patients who underwent CT angiography of the head-and-neck vessels were randomly divided into groups A and B with 30 cases in each group .Patients in group A received a conventional scan with 120 kVp and filterback projected ( FBP) reconstruction .Patients in group B received a low-dose scan with 80 kVp, and image reconstruction with FBP ( group B1) and IMR (group B2)algorithm.The contrast agent protocol were as follows the injection time in all patients was 10s, the injection rate was 4.5-5.5 ml/s in group A while 3.5-4.0 ml/s in group B.The CT values of artery, image noise, signal to noise ratio ( SNR) and contrast to noise ratio ( CNR) were measured and compared among three groups with One-way ANOVA analysis . Image quality was evaluated by two radiologists with five scale method , and compared with Kruskal-Wallis test .The CT dose index volume (CTDIvol) and dose length product ( DLP) were recorded and compared between groups with two independent samples t-test.Results The image quality scores of groups A , B1and B2 were 3-5, 2-4 and 3 -5, respectively .Image quality of twelve patients in group B 1 couldn′t meet the diagnostic requirements but none in group A and B 2.The objective image parameters SNR and CNR for group B 2 were equal to group A ( P >0.05), while those for group B1 were lower than group A (t=13.39, 9.45, P<0.05) and group B2 (t=-12.14, -9.96,P<0.05).CTDIvol and DLP for group B were separately 80.9%, 81.3%lower than those of group A(t=39.1, 32.2,P<0.05).The injection rate and contrast agent volume for group B were separately 22.0%, 22.1% lower than those of group A ( t=20.8, 20.8, P<0.01) .Conclusions It is feasible in CT angiography of the head-and-neck vessels with lower tube-voltage, lower injection rate, lower contrast agent dose and combining with iterative model reconstruction algorithm.This protocol can reduce the radiation dose by 81.3% while maintaining image quality .Trial registration Chinese clinical trial registry ,ChiCTR-BOC-16010060.