Grootendorst D J, Jose J, Wouters M W, van Boven H, Van der Hage J, Van Leeuwen T G, Steenbergen W, Manohar S, Ruers T J M
Faculty of Science and Technology, Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology, Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Lasers Surg Med. 2012 Sep;44(7):541-9. doi: 10.1002/lsm.22058. Epub 2012 Aug 6.
Excision and histological assessment of the first draining node (sentinel lymph node) is a frequently used method to assess metastatic lymph node involvement related to cutaneous melanoma. Due to the time required for accurate histological assessment, nodal status is not immediately available to the surgeon. Hence, in case histological examination shows metastases, the patient has to be recalled to perform additional lymphadenectomy. To overcome these drawbacks we studied the applicability of photoacoustic tomographic imaging as an intra-operative modality for examining the status of resected lymph nodes.
In melanoma patients undergoing lymphadectomy for metastatic disease, six suspect lymph nodes were photoacoustically (PA) imaged using multiple wavelengths. Histopathologal examination showed three nodes without tumor cells (benign nodes) and three nodes with melanoma cells (malignant nodes). PA images were compared with histology and anatomical features were analyzed. In addition, PA spectral analysis was performed on areas of increased signal intensity.
After correlation with histopathology, multiple areas containing melanoma cells could be identified in the PA images due to their increased response. Malignant nodes showed a higher PA response and responded differently to an increase in excitation wavelength than benign nodes. In addition, differences in anatomical features between the two groups were detected.
Photoacoustic detection of melanoma metastases based on their melanin content proves to be possible in resected human lymph nodes. The amount of PA signal and several specific anatomical features seem to provide additional characteristics for nodal analysis. However, it is as yet preliminary to designate a highly accurate parameter to distinguish between malignant and benign nodes. We expect to improve the specificity of the technique with a future implementation of an adjusted illumination scheme and depth correction for photon fluence.
对首站引流淋巴结（前哨淋巴结）进行切除及组织学评估是评估皮肤黑色素瘤相关转移性淋巴结受累情况的常用方法。由于准确的组织学评估需要时间，外科医生无法立即得知淋巴结状态。因此，如果组织学检查显示有转移，患者必须再次接受手术以进行额外的淋巴结清扫。为克服这些缺点，我们研究了光声断层成像作为术中检查切除淋巴结状态的一种方式的适用性。
在因转移性疾病接受淋巴结清扫术的黑色素瘤患者中，使用多个波长对六个可疑淋巴结进行了光声（PA）成像。组织病理学检查显示三个淋巴结无肿瘤细胞（良性淋巴结），三个淋巴结有黑色素瘤细胞（恶性淋巴结）。将PA图像与组织学结果进行比较，并分析其解剖特征。此外，对信号强度增加的区域进行了PA光谱分析。
与组织病理学结果相关联后，由于黑色素瘤细胞区域的反应增强，在PA图像中可以识别出多个含有黑色素瘤细胞的区域。恶性淋巴结显示出更高的PA反应，并且与良性淋巴结相比，对激发波长增加的反应不同。此外，还检测到两组之间在解剖特征上的差异。
基于黑色素含量对切除的人体淋巴结中的黑色素瘤转移灶进行光声检测是可行的。PA信号量和一些特定的解剖特征似乎为淋巴结分析提供了额外的特征。然而，目前指定一个高度准确的参数来区分恶性和良性淋巴结仍为时过早。我们期望通过未来实施调整后的照明方案和光子通量深度校正来提高该技术的特异性。
