冠状动脉CTA双低技术的临床应用

Clinical application of low kilovolt technique combining low concentration of contrast medium in coronary CT angiography

目的探讨应用双低技术——低千伏(100 kV)技术联合低对比剂浓度在冠状动脉CT血管造影(CCTA)中的可行性。方法选取拟行冠状动脉CTA检查患者80例患者(体重指数≤26.0 kg/m2),随机分为A、B两组,A组(n=40)采用100kV,270 mg/ml威视派克对比剂及自适应迭代算法重建(ASiR),B组(n=40)采用120 kV,350 mg/ml欧乃派克对比剂及滤波反投影算法重建(FBP)。测量主动脉、皮下脂肪和竖脊肌的CT值和SD值,平均SD值计算为图像噪声。测量左冠状动脉前降支(LAD),左冠状动脉回旋支(LCX)和右冠状动脉(RCA)的CT值和SD值,并计算对比噪声比(CNR)。采用5分法对所有图像进行主观质量评分。记录CT剂量指数,并进行有效辐射剂量计算。结果A组患者平均碘用量比B组患者下降22.8%。两组患者LAD、LCX和RCA血管CT值、CNR值、图像噪声及图像质量主观评分,均无统计学差异(P均>0.05)。A组患者的有效辐射剂量明显低于B组患者,差异有统计学意义(P<0.05)。结论对于体重指数≤26的患者,低对比剂浓度和低千伏(100 kV)相对于常规扫面能够提供相似的图像质量,并减少对比剂的碘用量及有效辐射剂量。

Objective To discuss the feasibility of low kilovolt （100 kV） technique combining low concentration of contrast medium in coronary CT angiography （CCTA）. Methods The patients （n=80, BMI≤26） with planed CCTA were chosen and randomly divided into group A and group （each n=40）. Group A was given low-kV （100 kV） CCTA with Visipaque （270 mg/mL） and self-adaptive iterative reconstruction algorithm （ASiR）, and group B, routine kV （120 kV） CCTA with Omnipaque （350 mg/mL） and filter back-projection algorithm （FBP）. The CT values and SD values of aorta, subcutaneous fat and erector spine muscle were measured, and mean SD value was calculated as image noise. The CT values and SD values of left anterior descending artery （LAD）, left circumflex （LCX） and right coronary artery （RCA） were measured, and contrast-to-noise ratio （CNR） was calculated. All images were given quality subjective scoring by using 5-score method. The CT dose index was recorded and effective radiation dose was calculated. Results The average iodine dosage decreased by 22.8%in group A compared with group B. The CT values, CNR values, image noise and image quality subjective scores of LAD, LCX and RCA had no statistical difference between 2 groups （all P〉0.05）. The effective radiation dose was significantly lower in group A than that in group B （P〈0.05）. Conclusion To the patients with BMI≤26, low concentration of contrast medium and low kilovolt CCTA can provide similar image quality, lower iodine dosage and lower effective radiation dose compared with conventional scanning.