van der Velden Sandra, Bastiaannet Remco, Braat Arthur J A T, Lam Marnix G E H, Viergever Max A, de Jong Hugo W A M
Radiology and Nuclear Medicine, UMC Utrecht, Mail E01.132, PO Box 85500, 3508 GA, Utrecht, Netherlands. Image Sciences Institute, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, Netherlands.
Phys Med Biol. 2017 Oct 12;62(21):8210-8225. doi: 10.1088/1361-6560/aa8840.
Radioembolisation with yttrium-90 (Y) is increasingly used as a treatment of unresectable liver malignancies. For safety, a scout dose of technetium-99m macroaggregated albumin (Tc-MAA) is used prior to the delivery of the therapeutic activity to mimic the deposition of Y. One-day procedures are currently limited by the lack of nuclear images in the intervention room. To cope with this limitation, an interventional simultaneous fluoroscopic and nuclear imaging device is currently being developed. The purpose of this simulation study was to evaluate the accuracy of estimating the lung shunt fraction (LSF) of the scout dose in the intervention room with this device and compare it against current clinical methods.
A male and female XCAT phantom, both with two respiratory profiles, were used to simulate various LSFs resulting from a scout dose of 150 MBq Tc-MAA. Hybrid images were Monte Carlo simulated for breath-hold (5 s) and dynamic breathing (10 frames of 0.5 s) acquisitions. Nuclear images were corrected for attenuation with the fluoroscopic image and for organ overlap effects using a pre-treatment CT-scan. For comparison purposes, planar scintigraphy and mobile gamma camera images (both 300 s acquisition time) were simulated. Estimated LSFs were evaluated for all methods and compared to the phantom ground truth.
In the clinically relevant range of 10-20% LSF, hybrid imaging overestimated LSF with approximately 2 percentage points (pp) and 3 pp for the normal and irregular breathing phantoms, respectively. After organ overlap correction, LSF was estimated with a more constant error. Errors in planar scintigraphy and mobile gamma camera imaging were more dependent on LSF, body shape and breathing profile.
LSF can be estimated with a constant minor error with a hybrid imaging device. Estimated LSF is highly dependent on true LSF, body shape and breathing pattern when estimated with current clinical methods. The hybrid imaging device is capable of accurately estimating LSF within a few seconds in an interventional setting.
钇-90（Y）放射性栓塞术越来越多地用于治疗不可切除的肝脏恶性肿瘤。为确保安全，在给予治疗活性物质之前，先使用99m锝标记的大聚合白蛋白（Tc-MAA）进行预注射剂量，以模拟Y的沉积。目前，由于介入室缺乏核图像，一日手术受到限制。为应对这一限制，目前正在研发一种介入性同步荧光透视和核成像设备。本模拟研究的目的是评估使用该设备在介入室中估计预注射剂量的肺分流分数（LSF）的准确性，并将其与当前临床方法进行比较。
使用具有两种呼吸模式的男性和女性XCAT体模，模拟150 MBq Tc-MAA预注射剂量产生的各种LSF。对屏气（5秒）和动态呼吸（10帧，每帧0.5秒）采集进行蒙特卡罗模拟混合图像。使用荧光透视图像对核图像进行衰减校正，并使用治疗前CT扫描对器官重叠效应进行校正。为作比较，模拟了平面闪烁显像和移动γ相机图像（采集时间均为300秒）。对所有方法的估计LSF进行评估，并与体模真实值进行比较。
在临床相关的10%-20%LSF范围内，混合成像分别高估了正常呼吸和不规则呼吸体模的LSF约2个百分点（pp）和3个pp。在进行器官重叠校正后，LSF估计误差更恒定。平面闪烁显像和移动γ相机成像中的误差更依赖于LSF、体型和呼吸模式。
使用混合成像设备可以以恒定的微小误差估计LSF。使用当前临床方法估计LSF时，其高度依赖于真实LSF、体型和呼吸模式。混合成像设备能够在介入环境中几秒钟内准确估计LSF。
