Ebner Lukas, Bütikofer Yanik, Ott Daniel, Huber Adrian, Landau Julia, Roos Justus E, Heverhagen Johannes T, Christe Andreas
1 Department of Diagnostic, Interventional and Pediatric Radiology, Hospital and University of Bern Inselspital, Freiburgstrasse 10, Bern CH-3010, Switzerland.
AJR Am J Roentgenol. 2015 Apr;204(4):727-35. doi: 10.2214/AJR.14.12921.
The purpose of this study was to investigate the feasibility of microdose CT using a comparable dose as for conventional chest radiographs in two planes including dual-energy subtraction for lung nodule assessment.
We investigated 65 chest phantoms with 141 lung nodules, using an anthropomorphic chest phantom with artificial lung nodules. Microdose CT parameters were 80 kV and 6 mAs, with pitch of 2.2. Iterative reconstruction algorithms and an integrated circuit detector system (Stellar, Siemens Healthcare) were applied for maximum dose reduction. Maximum intensity projections (MIPs) were reconstructed. Chest radiographs were acquired in two projections with bone suppression. Four blinded radiologists interpreted the images in random order.
A soft-tissue CT kernel (I30f) delivered better sensitivities in a pilot study than a hard kernel (I70f), with respective mean (SD) sensitivities of 91.1%±2.2% versus 85.6%±5.6% (p=0.041). Nodule size was measured accurately for all kernels. Mean clustered nodule sensitivity with chest radiography was 45.7%±8.1% (with bone suppression, 46.1%±8%; p=0.94); for microdose CT, nodule sensitivity was 83.6%±9% without MIP (with additional MIP, 92.5%±6%; p<10(-3)). Individual sensitivities of microdose CT for readers 1, 2, 3, and 4 were 84.3%, 90.7%, 68.6%, and 45.0%, respectively. Sensitivities with chest radiography for readers 1, 2, 3, and 4 were 42.9%, 58.6%, 36.4%, and 90.7%, respectively. In the per-phantom analysis, respective sensitivities of microdose CT versus chest radiography were 96.2% and 75% (p<10(-6)). The effective dose for chest radiography including dual-energy subtraction was 0.242 mSv; for microdose CT, the applied dose was 0.1323 mSv.
Microdose CT is better than the combination of chest radiography and dual-energy subtraction for the detection of solid nodules between 5 and 12 mm at a lower dose level of 0.13 mSv. Soft-tissue kernels allow better sensitivities. These preliminary results indicate that microdose CT has the potential to replace conventional chest radiography for lung nodule detection.
本研究旨在探讨在两个平面上使用与传统胸部X光片相当剂量的微剂量CT进行双能减影以评估肺结节的可行性。
我们使用带有人工肺结节的仿真人体胸部模型，对65个胸部模型中的141个肺结节进行了研究。微剂量CT参数为80 kV和6 mAs，螺距为2.2。应用迭代重建算法和集成电路探测器系统（Stellar，西门子医疗）以最大程度降低剂量。重建最大密度投影（MIP）。在两个投影方向上采集胸部X光片并进行骨抑制。四位不知情的放射科医生随机顺序解读图像。
在一项初步研究中，软组织CT内核（I30f）比硬内核（I70f）具有更高的灵敏度，各自的平均（标准差）灵敏度分别为91.1%±2.2%和85.6%±5.6%（p = 0.041）。所有内核均能准确测量结节大小。胸部X光片对成簇结节的平均灵敏度为45.7%±8.1%（骨抑制后为46.1%±8%；p = 0.94）；对于微剂量CT，无MIP时结节灵敏度为83.6%±9%（附加MIP后为92.5%±6%；p<10⁻³）。读者1、2、3和4对微剂量CT的个体灵敏度分别为84.3%、90.7%、68.6%和45.0%。读者1、2、3和4对胸部X光片的灵敏度分别为42.9%、58.6%、36.4%和90.7%。在每个模型分析中，微剂量CT与胸部X光片的各自灵敏度分别为96.2%和75%（p<10⁻⁶）。包括双能减影的胸部X光片的有效剂量为0.242 mSv；对于微剂量CT，应用剂量为0.1323 mSv。
在0.13 mSv的较低剂量水平下，微剂量CT在检测5至12 mm实性结节方面优于胸部X光片和双能减影的组合。软组织内核具有更高的灵敏度。这些初步结果表明，微剂量CT有潜力取代传统胸部X光片用于肺结节检测。
