Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China.
Med Phys. 2013 Oct;40(10):102507. doi: 10.1118/1.4820976.
The temporal mismatch between PET and standard helical CT (HCT) causes substantial respiratory artifacts in PET reconstructed images when using HCT as the attenuation map. Previously we developed an interpolated average CT (IACT) method for attenuation correction (AC) and demonstrated its merits in simulations. In this study we aim to apply IACT in patients with thoracic lesions using an active breathing controller (ABC).
Under local ethics approval, we recruited 15 patients with a total of 18 lesions in different thoracic regions: left upper lobe (2), right upper lobe (4), right hilum (3), right lower lobe (3), left hilum (2), and esophagus (4). All patients underwent whole body PET scans 1 h after 300-480 MBq (18)F-FDG injection, depending on the patients' weight. The PET sinograms were reconstructed with AC using: (i) standard HCT [120 kV, smart mA (30-150 mA), 0.984:1 pitch] and (ii) IACT obtained from end-inspiration and end-expiration breath-hold HCTs (120 kV, 10 mA, 0.984:1 pitch) aided by ABC. IACT was obtained by averaging the intensity of two extreme phases and the interpolated phases between them, where the nonlinear interpolation was obtained by B-spline registration and with an empirical sinusoidal function. The SUV max, SUV mean, and the differences of centroid-of-lesion (d) between PET and different CT schemes were measured for each lesion.
From visual inspection, the respiratory artifacts and blurring generally reduced in the thoracic region for PET IACT. Matching between CT and PET improved for PET IACT, with an average decrease of d for 1.34 ± 1.79 mm as compared to PET HCT. The SUV max and SUV mean were consistently higher for PET IACT versus PET HCT for all lesions, with (30.95 ± 18.63)% and (22.39 ± 15.91)% average increase, respectively.
IACT-ABC reduces respiratory artifacts, PET/CT misregistration and enhances lesion quantitation. This technique is a robust and low dose AC protocol for clinical oncology application especially in the thoracic region.
当使用螺旋 CT（HCT）作为衰减图时，PET 与标准 HCT 之间的时间不匹配会导致 PET 重建图像中出现大量呼吸伪影。我们之前开发了一种用于衰减校正（AC）的插值平均 CT（IACT）方法，并在模拟中证明了其优点。在这项研究中，我们旨在使用主动呼吸控制器（ABC）在患有胸部病变的患者中应用 IACT。
在当地伦理委员会的批准下，我们招募了 15 名患者，共 18 个病变位于不同的胸部区域：左肺上叶（2 个）、右肺上叶（4 个）、右肺门（3 个）、右肺下叶（3 个）、左肺门（2 个）和食管（4 个）。所有患者均在注射 300-480MBq（18）F-FDG 后 1 小时行全身 PET 扫描，具体取决于患者体重。使用以下方法对 PET 正弦图进行 AC 重建：（i）标准 HCT[120kV、智能毫安（30-150mA）、0.984:1 螺距]和（ii）IACT，通过 ABC 辅助，从吸气末和呼气末屏气 HCT（120kV、10mA、0.984:1 螺距）中获得。IACT 通过平均两个极端相位的强度和它们之间的插值相位来获得，其中非线性插值通过 B 样条配准和经验正弦函数获得。测量每个病变的最大标准摄取值（SUV max）、平均标准摄取值（SUV mean）和病变中心（d）在 PET 和不同 CT 方案之间的差异。
从视觉检查来看，IACT 通常可以减少胸部区域的呼吸伪影和模糊。与 PET HCT 相比，IACT 改善了 CT 与 PET 的匹配程度，病变中心的平均差异（d）平均减少了 1.34±1.79mm。与 PET HCT 相比，所有病变的 SUV max 和 SUV mean 均较高，分别为（30.95±18.63）%和（22.39±15.91）%。
IACT-ABC 减少了呼吸伪影、PET/CT 配准错误，并提高了病变定量。该技术是一种用于临床肿瘤学应用的强大且低剂量的 AC 方案，特别是在胸部区域。
