Luhur Reny, Schuijf Joanne D, Mews Jürgen, Blobel Jörg, Hamm Bernd, Lembcke Alexander
1 Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Charité - Universitätsmedizin Berlin, Campus Charité Mitte , Berlin , Germany.
2 Center for Medical Research & Development Europe,Toshiba Medical Systems Europe BV , Toshiba Medical Systems Europe BV , Zoetermeer , Netherlands.
Br J Radiol. 2018 Apr;91(1084):20170678. doi: 10.1259/bjr.20170678. Epub 2018 Jan 10.
To assess the accuracy of an iterative reconstruction (IR) technique for coronary artery calcium scoring with reduced radiation dose.
163 consecutive patients underwent twofold scanning by 320-row detector CT at 120 kVp. A low-dose scan at 25% tube current but with standard scan length (14 cm) was followed by a standard dose scan with routine tube current but reduced scan length (10 cm). Reduced dose images were constructed using filtered back-projection (FBP) and IR (adaptive iterative dose reduction in three dimensions). The standard dose scan reconstructed with FBP served as the gold standard for comparisons. Image noise and Agatston coronary calcium scores were determined and compared between the groups.
Compared with FBP at standard dose, noise at reduced dose increased markedly with FBP but remained low with IR. Mean Agatston score with FBP at reduced dose showed a significant increase as compared with FBP at standard dose. No significant difference was observed when applying IR at reduced dose. At reduced dose, 38 (23.3%) patients were reassigned to a different cardiovascular risk category with FBP but only 8 (4.9%) with IR. Out of 47 patients with a zero Agatston score, 15 patients (31.9%) were false-positive with FBP at reduced dose, but no false positives were found with IR.
IR allows accurate coronary artery calcium scoring with a radiation dose reduced by 75%. Advances in knowledge: The application of adaptive iterative dose reduction in three dimensions allows the maintenance of accurate Agatston scores and risk stratification at significantly reduced tube current, thus reducing the patient's exposure to ionizing radiation.
评估一种用于冠状动脉钙化评分的迭代重建（IR）技术在降低辐射剂量时的准确性。
163例连续患者接受了320排探测器CT在120 kVp下的两次扫描。先进行一次低剂量扫描（管电流为25%但扫描长度标准，14 cm），随后进行一次标准剂量扫描（管电流常规但扫描长度缩短，10 cm）。使用滤波反投影（FBP）和IR（三维自适应迭代剂量降低）构建低剂量图像。用FBP重建的标准剂量扫描作为比较的金标准。测定并比较两组的图像噪声和阿加斯顿冠状动脉钙化评分。
与标准剂量下的FBP相比，低剂量下FBP的噪声显著增加，而IR的噪声仍较低。低剂量下FBP的平均阿加斯顿评分与标准剂量下的FBP相比显著增加。低剂量应用IR时未观察到显著差异。在低剂量下，38例（23.3%）患者用FBP重新分类到不同的心血管风险类别，但用IR时只有8例（4.9%）。在47例阿加斯顿评分为零的患者中，15例（31.9%）在低剂量下用FBP出现假阳性，但用IR未发现假阳性。
IR可在辐射剂量降低75%的情况下实现准确的冠状动脉钙化评分。知识进展：三维自适应迭代剂量降低的应用能够在显著降低管电流的情况下维持准确的阿加斯顿评分和风险分层，从而减少患者接受的电离辐射暴露。
