Biomedical Photonic Imaging Group, MIRA Institute, University of Twente, AE, Enschede, The Netherlands.
Contrast Media Mol Imaging. 2013 Jan-Feb;8(1):83-91. doi: 10.1002/cmmi.1498.
Detection of tumor metastases in the lymphatic system is essential for accurate staging of malignancies. Commercially available superparagmagnetic nanoparticles (SPIOs) accumulate in normal lymph tissue after injection at a tumor site, whereas less or no accumulation takes place in metastatic nodes, thus enabling lymphatic staging using MRI. We verify for the first time the potential of SPIOs, such as Endorem(®) as a novel photoacoustic (PA) contrast agent in biological tissue. We injected five Wistar rats subcutaneously with variable amounts of Endorem(®) and scanned the resected lymph nodes using a tomographic PA setup. Findings were compared using histology, vibrating sample magnetometry (VSM) and 14 T MR-imaging. Our PA setup was able to detect the iron oxide accumulations in all the nodes containing the nanoparticles. The distribution inside the nodes corresponded with both MRI and histological findings. VSM revealed that iron quantities inside the nodes varied between 51 ± 4 and 11 ± 1 µg. Nodes without SPIO enhancement did not show up in any of the PA scans. Iron oxide nanoparticles (Endorem(®)) can be used as a PA contrast agent for lymph node analysis and a distinction can be made between nodes with and nodes without the agent. This opens up possibilities for intra-operative nodal staging for patients undergoing nodal resections for metastatic malignancies.
在淋巴系统中检测肿瘤转移对于恶性肿瘤的准确分期至关重要。市售的超顺磁纳米颗粒（SPIOs）在肿瘤部位注射后会积聚在正常淋巴组织中，而在转移性淋巴结中则很少或没有积聚，因此可以使用 MRI 进行淋巴分期。我们首次验证了 SPIOs（如 Endorem(®)）作为一种新型光声（PA）对比剂在生物组织中的潜力。我们向五只 Wistar 大鼠皮下注射不同剂量的 Endorem(®)，并使用层析 PA 设备扫描切除的淋巴结。使用组织学、振动样品磁强计（VSM）和 14 T MR 成像比较结果。我们的 PA 设备能够检测到所有含有纳米颗粒的淋巴结中的氧化铁积聚。淋巴结内的分布与 MRI 和组织学结果一致。VSM 显示，节点内的铁量在 51±4 和 11±1 µg 之间变化。没有 SPIO 增强的节点在任何 PA 扫描中都没有显示出来。氧化铁纳米颗粒（Endorem(®)）可用作 PA 对比剂用于淋巴结分析，并可以区分有和没有该试剂的淋巴结。这为接受转移性恶性肿瘤淋巴结切除术的患者提供了术中淋巴结分期的可能性。
