Segmentation of lung lesion volume by adaptive positron emission tomography image thresholding
Segmentation of lung lesion volume by adaptive positron emission tomography image thresholding
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DOI：
10.1002/(sici)1097-0142(19971215)80:12
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发表时间：
1997-12-15
期刊：
影响因子：
6.2
通讯作者：
Humm, JL
中科院分区：
文献类型：
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作者：
Erdi, YE;Mawlawi, O;Humm, JL
背景放射性核素治疗中的常见方案是施用示踪剂剂量的放射性药物，通过伽马成像确定其病变摄取和生物分布，然后使用该信息来确定最有效的治疗剂量。这种治疗计划方法可用于用正电子发射断层扫描（PET）准确地定量病变和器官的活性和体积。在这篇文章中，作者重点介绍了使用PET与计算机断层扫描（CT）相结合来确定适当的感兴趣体积（VVI）。作者开发了一种自动图像分割方案，以确定在可变背景活动条件下PET图像中肺转移灶的范围。椭圆形Jaszczak体模含有一组体积范围为0.4 - 5.5 mL的球体，填充有与肺病变中临床观察到的活性相对应的F-18活性（2-3 μ Ci/mL）。在冷背景下采集图像，然后在可变的源-背景（S/B）比下采集图像：7.4、5.5、3.1和2.8。对10例患者的17个原发性或转移性肺病变进行了病变分级分析，应用来自体模实验的最佳阈值。根据CT图像确定肺部病变的初始体积估计值。在F-18-fluoro-2-deoxy-D-glucose（（18）FDG）-PET图像上获得相应病变的近似S/B比值。根据病变大小的CT估计和S/B比的PET估计，可以选择适当的最佳阈值。将阈值应用于PET图像以获得病变活动和病变体积的最终估计。体模数据分析表明，对于大于4 mL的球体体积，图像分割收敛到固定阈值（从36%到44%），确切值取决于S/B比。对于患者，使用最佳阈值模式显示CT的初始体积与18FDG-PET扫描的最终体积之间具有良好的相关性（r = 0.999）（P < 0.02）。这些体积的平均差异为8. 4%。应用于PET扫描的自适应阈值方法可以定义肿瘤体积，这有望实现准确的肿瘤剂量测定。这种方法也适用于小病灶（
BACKGROUND. It is common protocol in radionuclide therapies to administer a tracer dose of a radiopharmaceutical, determine its lesion uptake and biodistribution by gamma imaging, and then use this information to determine the most effective therapeutic dose. This treatment planning approach can be used to quantitate accurately the activity and volume of lesions and organs with positron emission tomography (PET). In this article, the authors focus on the specification of appropriate volumes of interest (Vol) using PET in association with computed tomography (CT).METHODS. The authors have developed an automatic image segmentation schema to determine the Vol of metastases to the lung from PET images, under conditions of variable background activity. An elliptical Jaszczak phantom containing a set of spheres with volumes ranging from 0.4 to 5.5 mL was filled with F-18 activity (2-3 mu Ci/mL) corresponding to activities clinically observed in lung lesions. Images were acquired with a cold background and then with variable source-to-background (S/B) ratios of: 7.4, 5.5, 3.1, and 2.8. Lesion Vol analysis was performed on 10 patients with 17 primary or metastatic lung lesions, applying the optimum threshold values derived from the phantom experiments. Initial volume estimates for lung lesions were determined from CT images. Approximate S/B ratios were obtained for the corresponding lesions on F-18-fluoro-2-deoxy-D-glucose ((18)FDG)-PET images. From the CT estimate of the lesion size and the PET estimate of the S/B ratio, the appropriate optimum threshold could be chosen. The threshold was applied to the PET images to obtain lesion activity and a final estimate of the lesion volume.RESULTS. Phantom data analysis showed that image segmentation converged to a fixed threshold value (from 36% to 44%) for sphere volumes larger than 4 mL, with the exact value depending on the S/B ratios. For patients, the use of optimum threshold schema demonstrated a good correlation (r = 0.999) between the initial volume from CT and the final volume derived from the (18)FDG-PET scan (P < 0.02). The mean difference for those volumes was 8.4%.CONCLUSIONS. The adaptive thresholding method applied to PET scans enables the definition of tumor Vol, which hopefully leads to accurate tumor dosimetry. This method can also be applied to small lesions (