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International Journal of Biomedical Imaging
Volume 2014, Article ID 163652, 7 pages
http://dx.doi.org/10.1155/2014/163652
Research Article

Detection of Melanoma Metastases in Resected Human Lymph Nodes by Noninvasive Multispectral Photoacoustic Imaging

1Department of Surgery, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
2Biomedical Photonic Imaging Group, MIRA Institute, University of Twente, Post Box 217, 7500 AE Enschede, The Netherlands
3Melanoma Institute Australia, 40 Rocklands Road, North Sydney, NSW 2060, Australia
4Fujifilm Visualsonics Inc., Post Box 66, 3080 Yonge Street 6100, Toronto, ON, Canada
5Department of Pathology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
6Nanobiophysics Group, MIRA Institute, University of Twente, Post Box 217, 7500 AE Enschede, The Netherlands

Received 17 December 2013; Revised 23 May 2014; Accepted 23 May 2014; Published 16 June 2014

Academic Editor: Yue Wang

Copyright © 2014 Gerrit Cornelis Langhout et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads to an increased survival in node-positive patients. However, frozen section analysis of the sentinel node is not reliable and definitive histopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging can evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared multispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the present study is to examine the potential of multispectral photoacoustic imaging to identify melanoma metastasis in human lymph nodes. Methods. Three metastatic and nine benign lymph nodes from eight melanoma patients were scanned ex vivo using a Vevo LAZR multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology as gold standard. Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to identify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The penetration depth of the photoacoustic signal was up to 2 cm. Conclusion. Multispectral three-dimensional photoacoustic imaging allowed for selective identification of melanoma metastases in human lymph nodes.