Department of Electrical Engineering, Washington University, St. Louis, MO, United States of America.
Department of Radiology, Washington University, St. Louis, MO, United States of America.
Phys Med Biol. 2021 May 20;66(11). doi: 10.1088/1361-6560/abfb16.
This paper presents a novel PET geometry for breast cancer imaging. The scanner consists of a 'stadium' (a rectangle with two semi-circles on opposite sides) shaped ring, along with anterior and posterior panels to provide high sensitivity and high spatial resolution for an imaging field-of-view (FOV) that include both breasts, mediastinum and axilla. We simulated this total-breast PET system using GATE and reconstructed the coincidence events using a GPU-based list-mode image reconstruction implementing maximum likelihood expectation-maximization (ML-EM) algorithm. The rear-panel is made up of a single layer of LSO crystals (3.2 × 3.2 × 20 mmeach), while the 'stadium'-shaped elongated ring and the anterior panel are made with dual-layered LSO crystals (1.6 × 1.6 × 6 mmeach). The energy resolution and coincidence resolving time of all detectors are assumed to be 12% and 250 ps full-width-at-half-maximum, respectively. Various sized simulated lesions (4, 5, 6 mm) having 4:1, 5:1, and 6:1 lesion-to-background radioactivity concentration ratios, mimicking different biological uptakes, were strategically located throughout a volumetric torso phantom. We compared system sensitivity and lesion detectability of the dedicated total-breast PET system to a state-of-the-art clinical whole-body PET scanner. The mean sensitivity of the total-breast PET system is 3.21 times greater than that of a whole-body PET scanner in the breast regions. The total-breast PET system also provides better contrast-recovery coefficients for lesions of all sizes and lesion-to-background ratios in the breast when compared to a reference clinical whole-body PET scanner. Receiver operating characteristics (ROC) study shows the area under the ROC curve is 0.948 and 0.924 for the total-breast system and the whole-body PET scanner, respectively, in the detection of 4 mm diameter lesions with 4:1 lesion-to-background ratio. This study demonstrates our novel geometry can provide an imaging FOV larger than conventional PEM systems to simultaneously image both breasts, chest wall and axillae with significantly improved lesion detectability in the breasts when compared to a whole-body PET scanner.
本文提出了一种用于乳腺癌成像的新型正电子发射断层扫描（PET）几何结构。该扫描仪由一个“体育场”（一个带有两个半圆的矩形）形状的环组成，以及前壁和后壁，为包括两个乳房、纵隔和腋窝在内的成像视野（FOV）提供高灵敏度和高空间分辨率。我们使用 GATE 模拟了这个全乳房 PET 系统，并使用基于 GPU 的列表模式图像重建实现最大似然期望最大化（ML-EM）算法来重建符合事件。后壁由单层 LSO 晶体（每个 3.2×3.2×20mm）组成，而“体育场”形状的拉长环和前壁由双层 LSO 晶体（每个 1.6×1.6×6mm）组成。所有探测器的能量分辨率和符合分辨时间分别假设为 12%和 250ps 半高全宽。各种大小的模拟病变（4、5、6mm）具有 4:1、5:1 和 6:1 的病变与背景放射性浓度比，模拟不同的生物摄取，战略性地位于一个容积式躯干体模中。我们比较了专用全乳房 PET 系统与最先进的临床全身 PET 扫描仪的系统灵敏度和病变检测能力。全乳房 PET 系统在乳房区域的平均灵敏度比全身 PET 扫描仪高 3.21 倍。与参考临床全身 PET 扫描仪相比，全乳房 PET 系统还为所有大小和病变与背景比的病变提供了更好的对比恢复系数。接收器操作特性（ROC）研究表明，对于具有 4:1 病变与背景比的 4mm 直径病变的检测，全乳房系统和全身 PET 扫描仪的 ROC 曲线下面积分别为 0.948 和 0.924。这项研究表明，我们的新型几何结构可以提供比传统 PEM 系统更大的成像视野，同时对两个乳房、胸壁和腋窝进行成像，并与全身 PET 扫描仪相比，显著提高了乳房中的病变检测能力。
