Kogler Annie K, Polemi Andrew M, Nair Surabhi, Majewski Stanislaw, Dengel Lynn T, Slingluff Craig L, Kross Brian, Lee S J, McKisson J E, McKisson John, Weisenberger Andrew G, Welch Benjamin L, Wendler Thomas, Matthies Philipp, Traub Joerg, Witt Michael, Williams Mark B
Department of Physics, University of Virginia, Charlottesville, VA, USA.
Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
EJNMMI Res. 2020 Nov 11;10(1):139. doi: 10.1186/s13550-020-00729-8.
Assessment of lymphatic status via sentinel lymph node (SLN) biopsy is an integral and crucial part of melanoma surgical oncology. The most common technique for sentinel node mapping is preoperative planar scintigraphy of an injected gamma-emitting lymphatic tracer followed by intraoperative node localization using a non-imaging gamma probe with auditory feedback. In recent years, intraoperative visualization of SLNs in 3D has become possible by coupling the probe to an external system capable of tracking its location and orientation as it is read out, thereby enabling computation of the 3D distribution of the tracer (freehand SPECT). In this project, the non-imaging probe of the fhSPECT system was replaced by a unique handheld gamma camera containing an array of sodium iodide crystals optically coupled to an array of silicon photomultipliers (SiPMs). A feasibility study was performed in which preoperative SLN mapping was performed using camera fhSPECT and the number of detected nodes was compared to that visualized by lymphoscintigraphy, probe fhSPECT, and to the number ultimately excised under non-imaging probe guidance.
Among five subjects, SLNs were detected in nine lymphatic basins, with one to five SLNs detected per basin. A basin-by-basin comparison showed that the number of SLNs detected using camera fhSPECT exceeded that using lymphoscintigraphy and probe fhSPECT in seven of nine basins and five of five basins, respectively. (Probe fhSPECT scans were not performed for four basins.) It exceeded the number excised under non-imaging probe guidance for seven of nine basins and equaled the number excised for the other two basins.
Freehand SPECT using a prototype SiPM-based gamma camera demonstrates high sensitivity for detection of SLNs in a preoperative setting. Camera fhSPECT is a potential means for efficiently obtaining real-time 3D activity distribution maps in applications such as image-guided percutaneous biopsy, and surgical SLN biopsy or radioguided tumor excision.
通过前哨淋巴结（SLN）活检评估淋巴状态是黑色素瘤手术肿瘤学不可或缺的关键部分。前哨淋巴结定位的最常用技术是术前对注射的γ发射淋巴示踪剂进行平面闪烁扫描，然后术中使用带有听觉反馈的非成像γ探头进行淋巴结定位。近年来，通过将探头与一个能够在读取时跟踪其位置和方向的外部系统耦合，实现了术中对SLN进行三维可视化，从而能够计算示踪剂的三维分布（徒手单光子发射计算机断层扫描）。在本项目中，fhSPECT系统的非成像探头被一个独特的手持式γ相机取代，该相机包含一组碘化钠晶体，这些晶体与一组硅光电倍增管（SiPM）光学耦合。进行了一项可行性研究，其中使用相机fhSPECT进行术前SLN定位，并将检测到的淋巴结数量与淋巴闪烁造影、探头fhSPECT可视化的数量以及在非成像探头引导下最终切除的数量进行比较。
在五名受试者中，在九个淋巴区域检测到了SLN，每个区域检测到1至5个SLN。逐个区域比较显示，使用相机fhSPECT检测到的SLN数量分别在九个区域中的七个区域和五个区域中超过了使用淋巴闪烁造影和探头fhSPECT检测到的数量。（有四个区域未进行探头fhSPECT扫描。）在九个区域中的七个区域，它超过了在非成像探头引导下切除的数量，在另外两个区域与切除的数量相等。
使用基于SiPM的γ相机原型进行徒手单光子发射计算机断层扫描在术前环境中对检测SLN具有高灵敏度。相机fhSPECT是在图像引导经皮活检、手术SLN活检或放射性引导肿瘤切除等应用中有效获取实时三维活动分布图的潜在手段。
