Department of Radiology, Massachusetts General Hospital, 25 New Chardon St, 4th Floor, 467C, Boston, MA 02114, USA.
Radiology. 2011 May;259(2):565-73. doi: 10.1148/radiol.11101450. Epub 2011 Mar 8.
To compare lesion detection and image quality of chest computed tomographic (CT) images acquired at various tube current-time products (40-150 mAs) and reconstructed with adaptive statistical iterative reconstruction (ASIR) or filtered back projection (FBP).
In this Institutional Review Board-approved HIPAA-compliant study, CT data from 23 patients (mean age, 63 years ± 7.3 [standard deviation]; 10 men, 13 women) were acquired at varying tube current-time products (40, 75, 110, and 150 mAs) on a 64-row multidetector CT scanner with 10-cm scan length. All patients gave informed consent. Data sets were reconstructed at 30%, 50%, and 70% ASIR-FBP blending. Two thoracic radiologists assessed image noise, visibility of small structures, lesion conspicuity, and diagnostic confidence. Objective noise and CT number were measured in the thoracic aorta. CT dose index volume, dose-length product, weight, and transverse diameter were recorded. Data were analyzed by using analysis of variance and the Wilcoxon signed rank test.
FBP had unacceptable noise at 40 and 75 mAs in 17 and five patients, respectively, whereas ASIR had acceptable noise at 40-150 mAs. Objective noise with 30%, 50%, and 70% ASIR blending (11.8 ± 3.8, 9.6 ± 3.1, and 7.5 ± 2.6, respectively) was lower than that with FBP (15.8 ± 4.8) (P < .0001). No lesions were missed on FBP or ASIR images. Lesion conspicuity was graded as well seen on both FBP and ASIR images (P < .05). Mild pixilated blotchy texture was noticed with 70% blended ASIR images.
Acceptable image quality can be obtained for chest CT images acquired at 40 mAs by using ASIR without any substantial artifacts affecting diagnostic confidence.
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101450/-/DC1.
比较不同管电流-时间产品（40-150 mAs）采集并采用自适应统计迭代重建（ASIR）或滤波反投影（FBP）重建的胸部 CT 图像的病灶检出和图像质量。
本研究经机构审查委员会批准，并符合 HIPAA 规定，纳入 23 例患者（平均年龄 63 岁±7.3[标准差]；10 例男性，13 例女性）的 CT 数据。这些患者在 64 层多排 CT 扫描仪上进行扫描，扫描长度为 10cm，管电流-时间产品分别为 40、75、110 和 150 mAs。所有患者均签署了知情同意书。数据采用 30%、50%和 70%ASIR-FBP 混合重建。两名胸部放射科医生评估图像噪声、小结构的可视性、病灶的显著性和诊断信心。在胸主动脉中测量客观噪声和 CT 值。记录 CT 剂量指数容积、剂量-长度乘积、体重和横径。采用方差分析和 Wilcoxon 符号秩检验进行数据分析。
在 40 和 75 mAs 时，FBP 的噪声不可接受，分别有 17 例和 5 例患者如此，而 ASIR 在 40-150 mAs 时噪声可接受。30%、50%和 70%ASIR 混合重建的客观噪声（分别为 11.8±3.8、9.6±3.1 和 7.5±2.6）低于 FBP（15.8±4.8）（P<0.0001）。在 FBP 和 ASIR 图像上均未遗漏任何病灶。FBP 和 ASIR 图像上病灶的显著性均被评为清晰可见（P<0.05）。在 70%混合 ASIR 图像上可见轻微的像素化斑点状纹理。
在使用 ASIR 采集 40 mAs 胸部 CT 图像时，可获得可接受的图像质量，且无任何实质性伪影影响诊断信心。
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101450/-/DC1.
