低剂量前置门控冠脉CTA结合迭代重建技术在不典型胸痛患者中的应用研究

Low-dose coronary CTA with iterative reconstruction in patients with atypical chest pain

目的:评价应用迭代重建技术的半剂量冠状动脉CTA的图像质量、辐射剂量及以选择性冠状动脉造影为"金标准",探讨该技术诊断不典型胸痛患者冠脉病变的准确性。材料与方法:回顾分析132例不典型胸痛患者,其中男83例,女49例,平均年龄(54±8.3)岁,体质量指数26.4±2.4,进行前置门控低剂量256层螺旋CT血管造影(256层iCT,Philips)检查。120 kVp,105 mAs(管电流较常规降低50%)。原始数据采用迭代算法(iDOSE4)重建,迭代等级设置为IL4,卷积核:XCB。由两位有经验的放射科医师采用盲法对上述病例的横断面及CPR图像进行主观图像质量(对比度,血管边缘锐利度、主观噪声、可接受度)的4分法评估。计算二者主观评分的一致性及主观评分的均值,及冠脉节段显示的合格率。132例患者中,55例进行了选择性冠脉造影,以造影结果为金标准,以管腔直径狭窄≥50%为阳性,计算应用迭代重建技术的低剂量冠状动脉CTA诊断冠脉狭窄的敏感性、特异性、准确度、阳性预测值及阴性预测值。结果:两位观察者的主观评分达到了很好的一致性,对比度、血管边缘锐利度、主观噪声、可接受度的kappa值分别为0.66,0.72,0.82,0.84。应用迭代重建的半剂量冠脉CTA具有很好的图像质量,其对比度、血管边缘锐利度、噪声、可接受度的评分分别为3.97±0.17、3.86±0.35、3.89±0.32、3.83±0.38。可以诊断的节段占总节段的98.8%(1 865/1 887)。CTDI、DLP、ED分别为(8.19±0.18)mGy,(100.06±7.67)mGy.cm,(1.40±0.11)mSv。55例接受冠脉造影病人,低剂量结合迭代重建技术的图像表现出较高的准确性,其敏感性、特异性和准确度分别为93.75%、97.03%、97.04%(基于狭窄段),96%,93.3%和94.5%(基于病人)。结论:应用iDose4迭代重建技术的低剂量冠脉CTA能在辐射剂量减少50%条件下提供高质量的冠脉图像,并能准确检出不典型胸痛患者的冠脉病变。

Objective： To evaluate image quality （IQ） and effective radiation dose on 256-slice coronary CTA at 50% reduced radiation dose using iterative reconstruction （IR）（iDose4） and to assess the accuracy of this protocol in the diagnosis of coronary artery disease （CAD） in patients with atypical chest pain based on selective invasive coronary angiography as gold standard. Methods： Retrospective analysis of 132 consecutive patients（83 males, mean age 54 years, mean BMI 27） with atypical chest pain underwent low-dose 256-slice CT angiography with prospective gating （Brilliance iCT, Philips Healthcare）. The tube output was reduced by 50% compared to our routine institutional protocol. Scanning conditions were as follows： 120 kVp, 105 mAs, using prospective ECG-triggering at 75% of R-R interval. The HR was stabilized and controlled to ≤70 beats/min. Images were reconstructed using IR, using iterative levels 4（IR）, and standard convolution kernel（XCB）. Two radiologists evaluated IQ （contrast, sharpness, subjective noise and image acceptability） using a 4-point scale in a blinded manner. Subjective score consistency, the mean of subjective score and the acceptability display of coronary segments were calculate. Of the 132 patients, 55 also underwent coronary angiography, with percent diameter stenosis I〉50% as positive, to calculate the sensitivity, specificity, accuracy, positive and negative predicative values of coronary CTA with IR. Results： Subjective score consistency was achieved （Kappa value, 0.66±0.84）. The scores of contrast, sharpness, subjective noise and image acceptability were 3.97±0.17, 3.86±0.35, 3.89±0.32, 3.83±0.38, respectively. The percent of diagnostic segments in 132 patients was 98.8%（1 865/ 1 887）. The CTDI, DLP, and ED were （8.19±0.18） mGy, （100.06±7.67）mGy＇cm, and （1.40±0.11） mSv, respectively. In 55 patients underwent coronary angiography, low-dose scanning with IR exhibited high accuracy. The sensitivity, specificity, and accuracy were 93.75%, 97.03% and 97,04%, respectively （segment-based）; and 96%, 93.3%, and 94.5%（patient-based）. Conclusion： The iDose4 iterative reconstruction technique can maintain image quality in coronary CTA scanning at 50% radiation dose reduction, and can diagnose CAD with high accuracy.