Boos Johannes, Aissa Joel, Lanzman Rotem S, Heusch Philipp, Schimmöller Lars, Schleich Christoph, Thomas Christoph, Antoch Gerald, Kröpil Patric
Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany.
J Med Imaging Radiat Oncol. 2016 Apr;60(2):187-93. doi: 10.1111/1754-9485.12425. Epub 2016 Jan 7.
The objective of this study was to evaluate image quality and radiation dose of a CT angiography (CTA) protocol using 80 kVp in combination with iterative reconstruction and automated tube current modulation.
Ninety-five aortic CTA examinations were included in this study. A novel 80 kVp aortic CTA-protocol with iterative reconstruction was introduced in our department in March 2012 for patients with a body mass index (BMI) below 32 kg/m(2). The first 72 consecutive examinations were retrospectively assigned to group A (56 patients, 42 men, 14 women, mean age 69.6 ± 10.7 years, BMI range 19.7-31.1 kg/m(2)). For comparison, the last 23 consecutive examinations performed with the old protocol (100 kVp) were assigned to group B (21 patients, 13 men, 8 women, mean age 67.4 ± 11.1 years, BMI range 19.7-31.9 kg/m(2)). Thoracic and abdominal contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and aortic attenuation were assessed. Subjective image quality was rated on a 5-point scale (1 = non diagnostic; 5 = excellent). Furthermore, dose length product (DLP) and volumetric computed tomography dose index (CTDIvol) were analysed.
All examinations achieved diagnostic image quality. Attenuation of the aorta was significantly higher in group A compared with B (thoracic: 443.5 ± 90.5 Hounsfield units (HU) vs. 296.0 ± 61.0 HU; abdominal: 426.3 ± 94.2 HU vs. 283.6 ± 60.5 HU; P < 0.05, respectively). CNR, SNR and subjective image quality were comparable between both groups (CNR: 12.8 ± 3.7 vs. 13.0 ± 7.4; SNR 14.4 ± 3.9 vs. 14.9 ± 8.2; subjective image quality: 4.3 ± 0.6 vs. 4.5 ± 0.6; P > 0.05, respectively). CTDIvol and DLP were significantly lower in group A (1.9 ± 0.5 mGy; 139.2 ± 41.1 mGy × cm) as compared with group B (4.2 ± 1.4 mGy; 292.1 ± 91.5 mGy × cm; P < 0.001, respectively).
Low-dose CTA of the aorta using 80 kVp with iterative reconstruction enables a significant dose reduction of up to 50% compared with a 100 kVp protocol in patients with a BMI below 32 kg/m(2) while diagnostic image quality is maintained.
本研究的目的是评估采用80千伏峰值（kVp）联合迭代重建和自动管电流调制的CT血管造影（CTA）方案的图像质量和辐射剂量。
本研究纳入了95例主动脉CTA检查。2012年3月，我们科室为体重指数（BMI）低于32kg/m²的患者引入了一种采用迭代重建的新型80 kVp主动脉CTA方案。前72例连续检查被回顾性地归入A组（56例患者，42例男性，14例女性，平均年龄69.6±10.7岁，BMI范围19.7 - 31.1kg/m²）。为作比较，将最后23例采用旧方案（100 kVp）的连续检查归入B组（21例患者，13例男性，8例女性，平均年龄67.4±11.1岁，BMI范围19.7 - 31.9kg/m²）。评估了胸部和腹部的对比噪声比（CNR）、信噪比（SNR）以及主动脉衰减。主观图像质量采用5分制评分（1 = 非诊断性；5 = 优秀）。此外，分析了剂量长度乘积（DLP）和容积CT剂量指数（CTDIvol）。
所有检查均达到诊断图像质量。A组主动脉的衰减显著高于B组（胸部：443.5±90.5亨氏单位（HU）对296.0±61.0 HU；腹部：426.3±94.2 HU对283.6±60.5 HU；P均<0.05）。两组之间的CNR、SNR和主观图像质量相当（CNR：12.8±3.7对13.0±7.4；SNR 14.4±3.9对14.9±8.2；主观图像质量：4.3±0.6对4.5±0.6；P均>0.05）。A组的CTDIvol和DLP显著低于B组（分别为1.9±0.5毫西弗（mGy）；139.2±41.1 mGy×cm），而B组为（4.2±1.4 mGy；292.1±91.5 mGy×cm；P均<0.001）。
对于BMI低于32kg/m²的患者，采用80 kVp联合迭代重建的主动脉低剂量CTA与100 kVp方案相比，可显著降低剂量达50%，同时保持诊断图像质量。
