Performance of a novel collimator for high-sensitivity brain SPECT
Performance of a novel collimator for high-sensitivity brain SPECT
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DOI：
10.1118/1.2143140
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发表时间：
2006-01-01
期刊：
影响因子：
3.8
通讯作者：
Kijewski, MF
中科院分区：
文献类型：
--
作者：
El Fakhri, G;Ouyang, J;Kijewski, MF
我们评估了由于一种新型的脑部单光子计算机断层扫描准直器在检测和评估任务中性能的改善。数据是在CeraSPECT(TM)扫描仪上使用新的和标准的准直器获取的。新的可变聚焦准直器SensOgrad(TM)对投影进行了不均匀的采样，中央区域显示得更多，以补偿来自中央大脑结构的计数的衰减。此外，它还利用了更多的柱面晶体表面。进行了两项体模研究。第一个体模是一个直径21厘米的圆柱形背景，包含9个体积从0.5到5厘米(3)的球体。TC-99m球体与本底活度比为10：1。每个准直器采集29个10min的数据集。第二个体模是放射支持设备(长滩，加利福尼亚州)纹状体体模，纹状体与背景的比例左侧为10：1，右侧为5：1。用每个准直器采集29个4分钟的数据集。在相同的模拟条件下，使用两个准直器对三名健康志愿者进行了~(99m)Tc-HMPAO的灌注成像。投影通过带非加窗斜坡过滤器的过滤反投影进行重建。计算非预白化匹配滤波信噪比(NPW-SNR)作为人类检测球形病变的替代指标。球体活动浓度、半径和位置坐标是通过使用迭代非线性算法将图像拟合到假设模型来同时估计的。由于在模型中加入了点扩散函数，因此分辨率恢复在估计过程中是隐含的。使用新的准直器，球体探测的NPW-SNR提高了1.5~2倍；对于纹状体模，SNR提高了54%。对于距离模体中心大于5ern的球体，用于估计球体活动浓度的信噪比提高了46%到89%。用标准准直器获取的图像在中心区域太过嘈杂，无法估计球体的活动。在99m-HMPAO人体研究中，皮质的SNR提高了21%到41%，基底节提高了66%，丘脑提高了74%。新的准直器大大提高了整个大脑的检测和估计性能。更高的灵敏度对于动态成像尤为重要。(C)2006年美国医学物理学家协会。
We assessed improvements in performance in detection and estimation tasks due to a novel brain single photon computed tomography collimator. Data were acquired on the CeraSPECT (TM) scanner using both new and standard collimators. The new variable focusing collimator SensOgrade (TM) samples the projections unequally, with central regions more heavily represented, to compensate for attenuation of counts from central brain structures. Furthermore, it utilizes more of the cylindrical crystal surface. Two phantom studies were performed. The first phantom was a 21-cm-diameter cylindrical background containing nine spheres ranging from 0.5 to 5 cm(3) in volume. Tc-99m sphere to background activity ratio was 10:1. Twenty-nine 10-min datasets were acquired with each collimator. The second phantom was the Radiology Support Devices (Long Beach, CA) striatal phantom with striatal-background ratios of 10:1 on the left and 5:1 on the right. Twenty-nine 4-min datasets were acquired with each collimator. Perfusion imaging using Tc-99m-HMPAO was also performed in three healthy volunteers using both collimators under identical simulations. Projections were reconstructed by filtered backprojection with an unwindowed ramp filter. The nonprewhitening matched filter signal-to-noise ratio (NPW-SNR) was computed as a surrogate for human performance in detecting spherical lesions. Sphere activity concentration, radius, and location coordinates were simultaneously estimated by fitting images to an assumed model using an iterative nonlinear algorithm. Resolution recovery was implicit in the estimation procedure, as the point spread function was incorporated into the model. NPW-SNR for sphere detection was 1.5 to 2 times greater with the new collimator; for the striatal phantom the improvement in SNR was 54%. The SNR for estimating sphere activity concentration improved by 46 to 89% for spheres located more than 5 ern from the phantom center. Images acquired with the standard collimator were too noisy in the central regions to allow estimation of sphere activity. In Tc-99m-HMPAO human studies, SNR was improved by 21 to 41 % in the cortex, 66% in the basal ganglia, and 74% in the thalamus. The new collimator leads to substantially improved detection and estimation performance throughout the brain. The higher sensitivity will be particularly important for dynamic imaging. (c) 2006 American Association of Physicists in Medicine.