双层探测器光谱 CT 100 kVp 单能量图像 在门静脉成像中的应用.

Objective To evaluate the image quality of CT portal venography (CTPV) under low radiation dose conditions at 100 kVp using a second-generation dual-layer detector spectral CT (DLCT). Methods A total of 110 patients [54 men, 56 women, mean age: (57.47±15.07) years] underwent abdominal contrast-enhanced DLCT from May 2023 to March 2024. The patients were randomly divided into a control group (120 kVp, n=50) and a study group (100 kVp, n=60). The original CTPV data from the control group were reconstructed into conventional mixed-energy images (CI), while the data from the study group were reconstructed into CI and virtual monoenergetic images (VMI) at 40-80 keV intervals (10 keV steps). The CT values, standard deviation (SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the main portal vein and its left and right branches were measured. Subjective image quality was assessed by two radiologists. Results The effective radiation dose (ED) for the study group [(1.92±0.21) mSv] was 52.59% lower than that of control group [(4.05±1.23) mSv]. The average CT values, SNR, and CNR of the portal vein and its branches in the 40, 50, and 60 keV VMIs of the study group were significantly higher than those in the CIs of both groups (all P<0.0001), with the highest SNR and CNR observed at 40 and 50 keV VMIs. There was no significant difference in the SNR and CNR between 40 and 50 keV VMIs (P<0.05). The SD of 40 and 50 keV VMIs in the study group was comparable to that of control (P>0.05) whereas the SD of 60-80 keV VMIs was significantly lower than that of control (P<0.05). Subjective image quality assessment showed that 50 keV VMI had the highest proportion of scores rated as 5 (best) at 75% with good interobserver agreement (all K>0.8). Conclusion Using 50 keV VMI with 100 kVp DLCT provides image quality that meets clinical diagnostic requirements while significantly reducing radiation dose compared to conventional images at 120 kVp. [ABSTRACT FROM AUTHOR]