宝石能谱CT GSI成像和常规成像在上腹部应用价值的对比研究

目的:探讨宝石能谱CT GSI扫描模式在上腹部检查中降低辐射剂量和优化图像质量的可行性及应用价值。方法:选择2016年9月至2016年12月期间我院40例拟行上腹部三期增强的患者,根据扫描模式将患者分为A组和B组,每组20例。A组患者采用宝石能谱CT常规扫描模式行螺旋扫描,管电压120 Kvp及自动毫安管电流,确定NI值为10。B组患者采用GSI模式行三期增强扫描收集门脉期图像。回顾性自适应统计迭代重建(ASIR)70kev单能量图像,应用ASIR Review工具收集0到100%ASIR的CT值、噪声值,计算图像信号噪声比(SNR)。记录各组剂量报告中CT剂量容积指数(CTDI vol)及剂量长度乘积(DLP),并计算有效剂量(ED),采用图像质量主观评分对图像进行评价。结果:B组CT值、噪声值及SNR均高于A组(P0.05),B组CTDIvol、DLP和ED均显著低于A组(P0.05);随着ASIR升高,SNR升高,但是图像质量主观评分先升高后降低。当ASIR为50%时,图像质量最高,不同ASIR的CT值、噪声值之间的差异无统计学意义(P0.05)。结论:宝石能谱CT GSI扫描模式的效果明显优于螺旋扫描,同时在降低图像噪声的前提下选择50%ASIR,可保障图像质量。

Comparative Study of Gemstone Spectrum CT GSI Imaging and Conventional Imaging in Upper Abdominal Application Value

ABSTRACT Objective: To explore the feasibility and application value of the gemstonespectrum CT GSI scanning mode in reduc- ing the radiation dose and optimizing image quality in the upper abdominal examination. Methods: A total of 40 patients, who underwent upper abdominal three stage enhancement in Guangyuan Central Hospital during September 2016 to December 2016, were selected and divided into group A(n=20) and group B(n=20) according to the scan mode. Group A was performed spiral scanning by gemstone spectrum CT conventional scanning mode(tube voltage: 120Kvp; tube current of automatic milliampere; NI value:10). Group B was performed three stage enhanced scanning by GSI mode to collect portal phase image. ASIR CT values and noise values from 0 to 100% were collected by ASIR Review tool[retrospective adaptive statistical iterative reconstruction (ASIR)70kev single energy image]. The image signal to noise ratio (SNR) was calculated.The CT dose volume index (CTDI vol) and dose length product (DLP) were recorded in each dose re- port, and the effective dose (ED) was calculated.The images were evaluated according to image subjective scores. Results: The CT value, noise value and SNR of group B were higher than those of group A (P<0.05). The CTDIvol, DLP and EDof group B were significantly lower than those of group A(P<0.05). With the increase of ASIR, the SNR increased, but subjective score of image quality increased at first and then decreased. When ASIR was 50%, the image quality was the best. There were no statistical differences in CT value and noise value between different ASIR, and noise value (P>0.05). Conclusion: The effect of gemstone spectrum CT GSI scanning mode is significantly better than spiral scanning.At the same time, under the premise of reducing the image noise, selecting 50% ASIR can ensure the image quality.