低管电压与低流速对比剂联合迭代算法在下肢动脉CTA中的应用

目的 探讨低流速对比剂、低电压扫描结合迭代重建算法在下肢动脉CTA检查中的应用价值。方法 收集60例接受双下肢动脉CTA检查者,将其随机分为两组、各30例,实验组:采用低管电压(80 kV)扫描,对比剂注射速率3.3 ml/s,迭代算法重建图像;对照组:采用常规管电压(120 kV),对比剂注射速率5.0 ml/s,使用滤波反投影法进行图像重建。扫描结束后记录容积剂量指数(CTDI)和剂量长度乘积(DLP)。测量腹部至小腿8个ROI及周围肌肉组织的CT值和标准差(图像噪声),计算CNR及SNR,并对图像质量进行评分。比较2组的辐射剂量、碘注射量、血管CT值及图像质量。结果 实验组的CTDI和DLP分别为(3.57±0.64) mGy和(429.26±97.60)mGy·cm,对照组分别为(7.23±0.86)mGy、(918.15±173.53)mGy·cm,二者差异有统计学意义(P均<0.001)。实验组平均碘注射量为(22.49±2.03)g,对照组(33.48±2.97)g,差异有统计学意义(t=2.58,P<0.05)。实验组8个ROI的平均血管CT值和图像噪声均高于对照组,差异有统计学意义(P均<0.05)。两组间CNR、SNR和图像质量主观评分差异无统计学意义(P均>0.05)。结论 采用80 kV管电压、3.3 ml/s对比剂注射速率联合迭代算法行双下肢动脉CTA检查,能够在保证图像质量的同时减少患者所接受的辐射剂量和碘注射量。

Application of low tube voltage CTA combined with low injection rate of contrast media and iterative reconstruction algorithm in lower extremity arteries

Objective To explore the application value of low tube voltage CTA in lower extremity arteries combined with low injection rate of contrast media and iterative reconstruction algorithm. Methods Totally 60 patients performed lower extremity artery CTA were collected and randomly divided into two groups (group A and group B, each n=30). Patients in group A accepted 80 kV-tube-voltage CTA with iterative reconstruction algorithm and 3.3 ml/s contrast media injection rate. Patients in group B, a conventional scan with 120 kV tube voltage, 5 ml/s injection rate of contrast media and filtered back projection (FBP) were performed. The CT dose index (CTDI) and dose length product (DLP)of each scan were recorded. The CT values and standard deviations (image noises) of arteries and surrounding muscles were measured. The SNR and CNR were calculated and image quality was scored. The radiation dose, iodine dosage, CT value and image quality were compared and analyzed. Results The CTDI and DLP were (3.57±0.64)mGy, (429.26±97.60) mGy·cm in group A, and (7.23±0.86)mGy, (918.15±173.53)mGy·cm in group B, respectively, and then the difference was statistically significant (both P<0.001). The difference of iodine dosage was statistically significant between the two groups (22.49±2.03]g vs 33.48±2.97]g, P<0.05). The mean CT values and image noises in group A were significantly higher than those in group B (both P<0.05), while there were no statistical differences in SNR, CNR and image quality between the two groups (both P>0.05). Conclusion The 80 kV tube voltage CTA with iterative reconstruction algorithm and 3.3 ml/s injection rate of contrast media in lower extremity artery can be used to reduce radiation dose and iodine dosage while keeping the image quality satisfactory.