Jakobs Tobias F, Wintersperger Bernd J, Herzog Peter, Flohr Thomas, Suess Christoph, Knez Andreas, Reiser Maximilian F, Becker Christoph R
Department of Clinical Radiology, University of Munich, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich, Germany.
Eur Radiol. 2003 Aug;13(8):1923-30. doi: 10.1007/s00330-003-1895-7. Epub 2003 May 21.
The aim of this study was to reduce radiation exposure in multislice CT (MSCT) coronary artery calcium screening using different tube settings, and to determinate its impact on the detection and quantification of coronary artery calcification. Forty-eight patients underwent routine MSCT coronary artery calcium scoring (Somatom VolumeZoom, Siemens, Forchheim, Germany) with retrospective ECG-gated data acquisition. Scanning was performed with a 4 x 2.5-mm collimation. In each patient data acquisition was performed twice using tube settings of 120 kVp with 133 mAs (protocol 1) and of 80 kVp with 300 mAs (protocol 2). Together with the 80-kVp protocol additional online ECG-related tube current modulation (ECG pulsing) was used. Three-millimeter overlapping slices (increment 1.5 mm) were calculated for each data set. Semi-automated calcium quantification was performed calculating absolute Ca-hydroxylapatite mass. In addition to patient examinations, the radiation exposure for both protocols was evaluated using computed tomography dose index (CTDI) phantom measurements. Protocol 2 showed a significantly lower patient radiation exposure than protocol 1 (0.72 vs 2.04 mSv; p<0.0001). The CTDI phantom measurements revealed a 65% reduction of radiation dose. Calcium scoring results of both protocols showed a high correlation ( r=0.99; p<0.0001) for absolute Ca-Hydroxylapatite mass measurements. Using 80-kVp protocols patient radiation exposure can be significantly reduced in MSCT coronary artery calcium screening without affecting the detection and quantification of coronary artery calcification; therefore, this technique should be used with retrospective ECG-gated cardiac CT examinations in patients with regular sinus rhythm.
本研究旨在通过使用不同的管设置减少多层螺旋CT（MSCT）冠状动脉钙化筛查中的辐射暴露，并确定其对冠状动脉钙化检测和定量的影响。48例患者接受了常规MSCT冠状动脉钙化评分（Somatom VolumeZoom，西门子，德国福希海姆），采用回顾性心电图门控数据采集。扫描采用4×2.5毫米准直。在每位患者中，数据采集使用120 kVp、133 mAs的管设置（方案1）和80 kVp、300 mAs的管设置（方案2）各进行两次。对于80 kVp方案，还使用了额外的在线心电图相关管电流调制（心电图脉冲）。为每个数据集计算3毫米重叠层厚（层厚增量1.5毫米）。采用半自动钙化定量法计算绝对羟基磷灰石钙质量。除患者检查外，还使用计算机断层扫描剂量指数（CTDI）体模测量评估两种方案的辐射暴露。方案2显示患者辐射暴露明显低于方案1（0.72 vs 2.04 mSv；p<0.0001）。CTDI体模测量显示辐射剂量降低了65%。两种方案的钙化评分结果在绝对羟基磷灰石钙质量测量方面显示出高度相关性（r=0.99；p<0.0001）。在MSCT冠状动脉钙化筛查中，使用80 kVp方案可显著降低患者辐射暴露，且不影响冠状动脉钙化的检测和定量；因此，对于窦性心律正常的患者，在回顾性心电图门控心脏CT检查中应采用该技术。
