双源CT 80 kV低管电压在冠状动脉CT血管成像中的可行性研究

Feasibility study of dual-source CT under low tube voltage of 80 kV in coronary CT angiography

目的探讨双源CT 80 kV低管电压在冠状动脉CT血管成像(CCTA)中的可行性。方法对2014年12月至2015年11月亳州市人民医院收治的行CCTA检查、体质指数(BMI)≤30 kg/m^2的56例患者,按检查顺序分成A组(100 kV、碘克沙醇320 mg I/mL)及B组(80 kV、碘克沙醇320 mg I/mL),每组各28例。比较两组患者的辐射剂量;测量升主动脉(AO)根部的CT值及噪声(SD)、图像的信噪比(SNR);测量左冠状动脉主干(LM)、左冠状动脉前降支(LAD)近段、左冠状动脉回旋支(LCX)近段、右冠状动脉(RCA)近段的CT值及邻近组织的CT值,计算LM、LAD、LCX、RCA近段的对比度噪声比(CNR)。采用Likert4分法对每组患者容积重组(VR)及最大密度投影重组(MIP)图像进行双盲主观分级评分,并作统计学分析。结果 A组辐射剂量(4.36±0.71)mSv高于B组(1.75±0.40)mSv,差异有统计学意义(P<0.05);B组AO、RCA、LM、LAD、LCX近段的CT值高于A组,差异有统计学意义(P<0.05)。B组图像的噪声(47.17±7.76)HU较A组(29.73±4.21)HU大,差异有统计学意义(P<0.05);两组图像的SNR、LM、LAD、LCX、RCA近段的CNR差异均无统计学意义(P>0.05);两组图像质量主观评分、用于诊断的冠脉节段数比较,差异无统计学意义(P>0.05)。结论对于BMI≤30 kg/m^2的患者,在80 kV低管电压条件下行CCTA,能明显降低患者X线辐射剂量,且图像质量能够满足临床诊断要求。

Objective To evaluate the feasibility of dual-source CT(DSCT)under low tube voltage of 80 kV in the patients receiving coronary CT angiography(CCTA).Methods From Dec 2014 to Nov 2015,56 cases of patients with body mass index(BMI)≤30 kg/m 2 underwent CCTA in our hospital were selected,and then divided into group A(100 kV,320 mgI/mL iodixanol)and group B(80 kV,320 mgI/mL iodixanol)according to their examination order,28 cases in each group.The radiation dosages between the two groups were compared,and the CT values and signal-to-noise ratios(SNR)at root of ascending aorta(AO)were measured.Then the CT values of left main coronary artery(LM),proximal segments of left anterior descending(LAD)and left circumflex(LCX)coronary arteries,proximal segment of right coronary artery(RCA)and adjacent tissues were also measured,and the contrast-to-noise ratios(CNR)of LM,proximal segments of LAD,LCX and RCA were further calculated.Statistical analysis was carried out after double-blind subjective grading of the patients’images of volume rendering(VR)and maximum intensity projection(MIP)by means of Likert four-point scale.Results The radiation dose in group A(4.36±0.71)mSv was significantly higher than that ingroup B(1.75±0.40)mSv(P<0.05).The CT values of AO,LM,and proximal segments of RCA,LAD and LCX in group B were higher than those in group A,with significant differences(P<0.05).The image noise in group B(47.17±7.76)HU was significantly higher than that in group A(29.73±4.21)HU(P<0.05).But there was no significant difference in the SNR of root of AO and the CNR of LM and proximal segments of RCA,LAD and LCX between the images of two groups(P>0.05).No significant difference was found in the subjective grades of image quality and the coronary segments for diagnosis between the two groups(P>0.05).Conclusion For patients with BMI≤30kg/m 2,operation of CCTA under low tube voltage of 80 kV could largely reduce the X-ray radiation dosage for the mand obtain images meeting the quality requirement of clinical diagnosis.