Joint reconstruction of Ictal/inter-ictal SPECT data for improved epileptic foci localization.
Joint reconstruction of Ictal/inter-ictal SPECT data for improved epileptic foci localization.
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DOI：
10.1002/mp.12167
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发表时间：
2017-04
期刊：
影响因子：
3.8
通讯作者：
Ouyang J
中科院分区：
文献类型：
--
作者：
Rakvongthai Y;Fahey F;Borvorntanajanya K;Tepmongkol S;Vutrapongwatana U;Zukotynski K;El Fakhri G;Ouyang J
为了提高定位癫痫灶的性能，我们开发了一种联合发作/发作间期SPECT重建方法，其中发作和发作间期SPECT投影同时重建以获得差分图像。我们已经开发了一种SPECT重建方法，共同重建发作和发作间期SPECT投影数据。我们进行了两个幻影和病人的研究，以评估我们的联合癫痫灶定位方法的性能相比，传统的减法，其中差分图像是通过减去发作间期图像从共同注册的发作图像。使用99 mTc和霍夫曼头部模型在两个不同的位置和方向采集两个低噪声SPECT投影数据集。在两个体模位置之一，还使用99 mTc填充的3.3 cm球体采集低噪声数据集，其冷衰减背景与霍夫曼体模相同。将这三个数据集合并并缩放以模拟低噪声临床发作（三种不同的病灶与背景对比度水平：1.25、1.55和1.70）和发作间期扫描。对于每个低噪声数据集，通过将泊松噪声添加到投影来生成25个噪声实现。使用传统减影和我们的联合方法计算差分图像中病变对比度的平均值和标准差（SD）。我们还将这两种方法应用于35个癫痫患者数据集。每个差分图像被提交给两个核医学医生定位病变，并指定一个置信水平。分析阅片者的数据，以获得减影法和联合法的局部响应接受者工作特征（LROC）曲线。对于体模研究，使用传统减影与我们的联合方法获得的差分图像中的平均病变对比度之间的差异随着迭代次数的增加而减小。与传统的减影方法相比，使用我们的联合方法在第10次迭代时病变对比度的SD降低范围分别为54.7%至68.2%（p<0.0005）和33.8%至47.9%（p<0.05）。在患者研究中，我们的联合方法分别将第一和第二读取器的LROC下的面积从0.24增加到0.34和从0.15增加到0.20。我们已经证明了我们的方法相比，目前在临床实践中使用的标准减法的性能提高。所提出的联合发作/发作间期重建方法产生更好的性能比传统的减影方法的癫痫灶定位。
To improve the performance for localizing epileptic foci, we have developed a joint ictal/inter-ictal SPECT reconstruction method in which ictal and inter-ictal SPECT projections are simultaneously reconstructed to obtain the differential image. We have developed a SPECT reconstruction method that jointly reconstructs ictal and inter-ictal SPECT projection data. We performed both phantom and patient studies to evaluate the performance of our joint method for epileptic foci localization as compared with the conventional subtraction method in which the differential image is obtained by subtracting the inter-ictal image from the co-registered ictal image. Two low-noise SPECT projection data sets were acquired using 99mTc and a Hoffman head phantom at two different positions and orientations. At one of the two phantom locations, a low-noise data set was also acquired using a 99mTc-filled 3.3-cm sphere with a cold attenuation background identical to the Hoffman phantom. These three datasets were combined and scaled to mimic low-noise clinical ictal (three different lesion-to-background contrast levels: 1.25, 1.55 and 1.70) and inter-ictal scans. For each low-noise data set, twenty-five noise realizations were generated by adding Poisson noise to the projections. The mean and standard deviation (SD) of lesion contrast in the differential images were computed using both the conventional subtraction and our joint methods. We also applied both methods to the 35 epileptic patient datasets. Each differential image was presented to two nuclear medicine physicians to localize a lesion and specify a confidence level. The readers’ data were analyzed to obtain the localized-response receiver operating characteristic (LROC) curves for both the subtraction and joint methods. For the phantom study, the difference between the mean lesion contrast in the differential images obtained using the conventional subtraction versus our joint method decreases as the iteration number increases. Compared with the conventional subtraction approach, the SD reduction of lesion contrast at the 10th iteration using our joint method ranges from 54.7% to 68.2% (p<0.0005), and 33.8% to 47.9% (p<0.05) for 2 and 4 million total inter-ictal counts, respectively. In the patient study, our joint method increases the area under LROC from 0.24 to 0.34 and from 0.15 to 0.20 for the first and second reader, respectively. We have demonstrated improved performance of our method as compared to the standard subtraction method currently used in clinical practice. The proposed joint ictal/inter-ictal reconstruction method yields better performance for epileptic foci localization than the conventional subtraction method.