Neuro-Imaging Group, MIRA Institute for Biomedical Engineering and Technical Medicine, University of Twente, 7500 AE Enschede, The Netherlands.
IEEE Trans Biomed Eng. 2013 Sep;60(9):2594-602. doi: 10.1109/TBME.2013.2261893. Epub 2013 May 6.
As the first step in developing a new clinical technique for the magnetic detection of colorectal sentinel lymph nodes (SLNs), a method is developed to measure the magnetic content in intact, formalin fixated lymph nodes using a vibrating sample magnetometer (VSM). A suspension of superparamagnetic nanoparticles is injected ex vivo around the tumor in the resected colon segments. A selection of three lymph nodes is excised from the region around the tumor and is separately measured in the VSM. The iron content in the lymph nodes is quantified from the magnetic moment curve using the Langevin model for superparamagnetism and a bimodal particle size distribution. Adverse, parasitic movements of the sample were successfully reduced by tight fixation of the soft tissue and using a small vibration amplitude. Iron content in the lymph nodes is detected with 0.5 μg accuracy and ranged from 1 to 51 μg. Histological staining confirmed iron presence. The current method of measuring intact biological tissue in a VSM is suitable to show the feasibility and merit of magnetic detection of SLNs in colorectal cancer. For clinical validation of magnetic SLN selection in colorectal cancer, a new magnetometer with high specificity for superparamagnetic nanoparticles is required.
作为开发用于检测结直肠前哨淋巴结（SLN）的新型临床磁性检测技术的第一步，我们开发了一种使用振动样品磁强计（VSM）来测量福尔马林固定完整淋巴结中磁性含量的方法。将超顺磁纳米粒子混悬液在切除的结肠段肿瘤周围进行离体注射。从肿瘤周围区域切除三个淋巴结，并在 VSM 中分别进行测量。使用超顺磁的朗之万模型和双峰粒径分布，从磁矩曲线中定量计算淋巴结中的铁含量。通过软组织的紧密固定和使用小的振动幅度，成功减少了样品的不利、寄生运动。淋巴结中的铁含量的检测精度为 0.5μg，范围为 1 至 51μg。组织学染色证实了铁的存在。目前在 VSM 中测量完整生物组织的方法适合证明结直肠癌中 SLN 磁性检测的可行性和优势。为了在结直肠癌中对磁性 SLN 选择进行临床验证，需要一种具有超顺磁纳米粒子高特异性的新型磁强计。
