Objective To discuss the application value of 320-slice CT low tube voltage variable helical pitch (VHP) technique in preoperative evaluation of patients undergoing transcatheter aortic valve replacement (TAVR) by analyzing the subjective and objective quality of preoperative CTA image of patients.

Methods A total of 96 cases of patients who planned to undergo aortic valve replacement from January 2016 to December 2020 were prospectively included. All patients underwent preoperative CTA examination with 320-slice spiral CT variable helical pitch (VHP) technique. According to the random number method, the patients were divided into 80 kV, 100 kV, and 120 kV groups, with 32 patients in each group, the dosage of contrast agent was 0.9, 1.1, and 1.2 mL/kg, and the flow rate was 3, 3.5, and 4 mL/s. Images of each group were evaluated using an iterative algorithm (AIDR), and image quality was evaluated using both subjective (Likert 5 method) and objective assessment methods (CT value, SD value, and contrast to noise ratioCNR). The image qualities of the left and right common carotid artery, ascending aortic root, and left and right femoral artery were compared among the 3 groups.

Results There were no statistically significant differences in gender, age, body mass index (BMI), and scanning time among the three groups. The significant differences in subjective scores were only observed in the left and right femoral artery among the three groups (P < 0.0 1). There were significant differences in CT values at the left and right common carotid artery and left and right femoral artery among the three groups (P < 0.001). There were significant differences in SD and CNR values at all levels among the three groups (P < 0.001). The dosage of contrast agents in the 80 kV group (57.70±9.01 mL) was lower than that in the 100 kV group (71.80±10.37 mL) and 120 kV group (75.20±11.08 mL, P < 0.01). In the 80 kV, 100 kV, and 120 kV groups, the dose length product (DLP) of patients was (1 096.88±155.20) mGy×cm, (963.02±137.90) mGy×cm, and (1 048.53±168.20) mGy×cm, and the mean effective radiation dose was 16.45, 14.44, and 15.73 mSv, respectively. The patients in the 100 kV group received the lowest radiation dose (P < 0.05).

Conclusions The 320-slice CT VHP technique can obtain good image quality at the tube voltages of 80, 100, and 120 kV, among which, the dosage of contrast agent is least at 80 kV, and the radiation dose received is lowest at 100 kV.