双低模式在中小体质指数患者肠系膜上动脉CTA中的应用研究

Application Research of Double-Low Model in Superior Mesenteric Artery CTA in Medium and Small Body Mass Index Patients

目的探讨双低模式在中小体质指数患者肠系膜上动脉CTA中应用的可行性与价值。方法前瞻性分析2017年9月至2018年3月期间行肠系膜上动脉CTA检查的患者80例。将其随机分为两组(常规组、双低组),每组40例,分别行常规和双低方案扫描,常规组采用管电压120 kV、250 mA、320 mgI/mL碘佛醇,双低组采用管电压80 kV、自动管电流40～440mA、270mgI/mL碘克沙醇。两组造影剂总量均根据患者体重计算(1.0mL/kg),注射速率为3.5mL/s。对图像质量进行主观评分,并测量右肾动脉层面腹主动脉、肠系膜上动脉、左侧竖脊肌CT值,计算肠系膜上动脉的信噪比、对比噪声比、图像灵敏度,患者的辐射剂量及碘负荷,比较两组间不同指标的差异。采用Wilcoxon秩和检验和独立样本t检验。结果两组间图像质量主观评分、对比剂用量、左侧竖脊肌CT值差异无统计学意义(P>0.05)。与常规扫描相比,双低组对比剂浓度、碘流率、总碘摄入量分别降低15.63%(50/320)、15.63%(175/1120)、15.98%(3.09/19.34);双低组肠系膜上动脉CT值、腹主动脉CT值分别提高43.03%(132.45/307.79)、47.12%(152.01/322.58);双低组噪声、信噪比(Signal Noise Ratio,SNR)、对比噪声比(Contrast To Noise Ratio,CNR)、图像灵敏度(Figure of Merit,FOM)分别提高20.14%(9.65/47.92)、19.16%(1.23/6.42)、28.11%(1.47/5.23)、623.56%(11.91/1.91),差异均有统计学意义(P<0.05);两组个性参数(性别比、年龄、体重、BMI)及扫描范围差异无统计学意义;双低组CTDIvol(mGy)、DLP(mGy·cm)、ED(mSv)分别降低76.76%(11.43/14.89)、77.91%(599.82/769.81)、77.92%(9/11.55);所有差异均有统计学意义(P<0.05)。结论中小体质指数患者行肠系膜上动脉CTA时应用低射线剂量、低浓度对比剂的双低方案切实可行,可获得满足临床诊断需求的理想血管图像,且大幅降低受检者接受的有效辐射剂量、降低碘流率、减少总碘摄入量、降低肾毒性。

Objective To explore the feasibility and value of double low model for superior mesenteric artery CTA in patients with medium and small body mass index. Methods A total of 80 patients who underwent superior mesenteric artery CTA examination between September 2017 and March 2018 were prospectively analyzed. They were randomly divided into two groups (conventional group and double low group), with 40 cases in each group receiving routine and double low scheme scanning, respectively. In the conventional group, the tube voltage was 120 kV, 250 mA, 320 mgI/mL iodobutol, while in the double low group, the tube voltage was 80 kV, automatic tube current 40-440 mA, and 270 mgI/mL iodoxacol. The total amount of contrast agent was calculated according to the patient's weight (1.0 mL/kg), and the injection rate was 3.5 mL/s. Routine and double low program scans were performed respectively. The image quality was evaluated subjectively, and CT values of the right renal artery level abdominal aorta, superior mesenteric artery, and left lateral spinal muscle were measured, and the signal-to-noise ratio (SNR), contrast to noise ratio (CNR), and image sensitivity of the superior mesenteric artery and radiation dose and iodine load in patients were calculated. Wilcoxon rank sum test and independent sample t test were used. Results There was no statistically significant difference in subjective ratings of images between the two groups (P<0.05). There was no significant difference in CT value between the two groups of contrast agents (P<0.05). The concentration of contrast agent, iodine flow rate and total iodine intake were reduced by 15.63%(50/320), 15.63%(175/1120) and 15.98%(3.09/19.34), respectively. The differences were statistically significant (P<0.05). The CT value of the superior mesenteric artery and the abdominal aorta were respectively increased by 43.03%(132.45/307.79) and 47.12%(152.01/322.58), and the differences were statistically significant (P<0.05). The SNR, CNR and figure of merit (FOM) of the two groups increased by 19.16%(1.23/6.42), 28.11%(1.47/5.23) and 623.56%(11.91/1.91), and the differences were statistically significant (P<0.05). There were no statistical differences between the two groups of personality parameters (sex ratio, age, weight, BMI) and scanning range. The CTDIvol (mGy), DLP (mGy·cm) and ED (mSv) of the two groups were reduced by 76.76%(11.43/14.89), 77.91%(599.82/769.81) and 77.92%(9/11.55), and there was a statistical difference (P<0.05). Conclusion The low-ray dose and low-concentration contrast medium are feasible for superior mesenteric artery CTA in patients with medium and small body mass index. The requirements of clinical diagnosis of superior vascular image can be obtained, and greatly reduce inspectors effective radiation dose, iodine flow rate, total iodine intake and nephrotoxicity.