Department of Electrical Engineering, Yuan Ze University, 135 Yuan-Tung Road, Chung-Li 320, Taiwan, ROC.
Comput Biol Med. 2013 Oct;43(10):1341-52. doi: 10.1016/j.compbiomed.2013.07.006. Epub 2013 Jul 15.
Patient-specific dosimetry calculations are often performed for radioiodine therapy in patients with Graves' hyperthyroidism. The radioiodine doses are typically calculated to deliver the desired amount of radiation based on gland size and radioactive iodine uptake. Thus the estimation of thyroid gland volume is of great importance for radioiodine therapy. In clinical practice, thyroid volume determinations are usually performed with ultrasonography (US) or with planar scintigraphy (PS). In traditional planar scintigraphic studies, the thyroid boundary is estimated using a fixed threshold value if the shape of the thyroid is well-defined or a manually drawn region of interest (ROI) if the thyroid shape is irregular. The thyroid volume is then calculated based on the area thus determined. Delineating the thyroid area on a planar scintigram is not easy when applying a fixed threshold value. Moreover, hand-drawn ROIs are time consuming, tedious, and highly operator-dependent. In this study, for a PS image, a fully automated thyroid volume estimation system mainly consisting of four steps, i.e. preprocessing, image contrast enhancement, image segmentation, and automated ROI finding, was proposed to obtain the maximum height and area of each thyroid lobe, and thus calculate the thyroid volume using either Himanka-Larsson's formula or Allen-Goodwin's formula. A set of 40 Graves's disease patients regarded as training set were used to determine empirically some parameters operated in the system. A set of 30 Graves's disease patients being independent of the training set, regarded as test set for thyroid volume measurements were used for comparisons and performance analyses. In this study, the US was adopted as a standard reference. The statistical analyses were performed with bias, precision, and relative differences. The results of thyroid volume estimation from the proposed approach correlated well with those from US, and the statistical performance analyses showed good agreement between them. In comparison, our automated approach with Allen-Goodwin's formula had not only good correlation with US (R(2)=0.99) but also the best bias (0.8), precision (±2.32 ml), and low relative differences (2.2 ± 6.1%). It is expected that this automated computer-assisted approach can help physicians in the determination of patient-specific administered activities for treatment of thyroid disease.
患者特异性剂量计算通常在 Graves 甲状腺功能亢进症患者的放射性碘治疗中进行。放射性碘剂量通常根据腺体大小和放射性碘摄取量计算，以提供所需的辐射量。因此，甲状腺体积的估计对于放射性碘治疗非常重要。在临床实践中，甲状腺体积的测定通常使用超声（US）或平面闪烁照相术（PS）进行。在传统的平面闪烁照相研究中，如果甲状腺形状定义良好，则使用固定的阈值来估计甲状腺边界，如果甲状腺形状不规则，则使用手动绘制的感兴趣区域（ROI）。然后根据确定的区域计算甲状腺体积。在应用固定阈值时，在平面闪烁图像上描绘甲状腺区域并不容易。此外，手动绘制 ROI 既耗时又乏味，并且高度依赖于操作者。在这项研究中，对于 PS 图像，提出了一种主要由四个步骤组成的全自动甲状腺体积估算系统，即预处理、图像对比度增强、图像分割和自动 ROI 查找，以获得每个甲状腺叶的最大高度和面积，并使用 Himanka-Larsson 公式或 Allen-Goodwin 公式计算甲状腺体积。一组 40 名 Graves 病患者被视为训练集，用于确定系统中操作的一些经验参数。一组 30 名 Graves 病患者与训练集无关，作为甲状腺体积测量的测试集，用于比较和性能分析。在这项研究中，采用 US 作为标准参考。采用偏倚、精度和相对差异进行统计分析。该方法的甲状腺体积估算结果与 US 吻合良好，统计学性能分析也显示出良好的一致性。相比之下，我们使用 Allen-Goodwin 公式的自动方法不仅与 US 具有良好的相关性（R(2)=0.99），而且偏倚（0.8）、精度（±2.32ml）和相对差异（2.2±6.1%）最低。预计这种自动计算机辅助方法可以帮助医生确定针对甲状腺疾病的特定患者给药活动。
