Novel technique changes lymph node biopsy, reduces radiation exposure in breast cancer patients

January 14, 2009

Information obtained from a new application of photoacoustic tomography (PAT) is worth its weight in gold to breast cancer patients.

For the first time, Lihong Wang, Ph.D., Gene K. Beare Distinguished Professor in the Department of Biomedical Engineering, with a joint appointment in Radiology, and Younan Xia, Ph.D., James M. McKelvey Professor in Biomedical Engineering, with a joint appointment in chemistry in Arts & Sciences, both at Washington University in St. Louis, have used gold nanocages to map sentinel lymph nodes (SLN) in a rat noninvasively using PAT. Wang's lab is the largest PAT lab in the world, credited with the invention of super-depth photoacoustic microscopy, and Xia's lab invented the gold nanocages.

Their work, supported by the National Institutes of Health, can minimize invasive surgical lymph node biopsy procedures to determine if breast cancer has metastasized and reduce the patient's exposure to radioactivity. The nanocages also have the potential to serve as an alternative to chemotherapy, to kill targeted cancers by heating them up. The research was published in a recent on-line issue of Nanoletters.

From heat, to expansion, to sound and an image

PAT blends optical and ultrasonic imaging to give high-resolution images of the body that contain information about physiology or tissue function. Molecules already present in the body (endogenous molecules), such as melanin, hemoglobin, or lipids, can be used as endogenous contrast agents for imaging. When light is shone on the tissue, the contrast agent absorbs the light, converts it to heat, and expands. This expansion is detected as sound and decoded into an image.

"Using pure optical imaging, it is hard to look deep into tissues at high resolution because light scatters. The useful photons run out of juice within one millimeter," Wang explained. "PAT improves tissue transparency by two to three orders of magnitude because sound scatters less than light. This allows us to see through the tissue by listening to the sound."

Exogenous contrast agents (found outside the body), like the gold nanocages developed by Xia's group, can be used to image parts of the body that even contain endogenous contrast agents. These nanocages are especially attractive because their properties can be tuned to give optimal contrast and gold is non-toxic.

"By controlling the synthesis, we can move the absorption peak for the nanocages to a region that allows them to be imaged deep in tissue. We can also attach biomolecules to the surface of the nanocages so they are targeted to cancer cells," Xia said.

Safe imaging, no radioactivity or surgery

The SLN, the first draining node, is often biopsied in breast cancer patients to determine if the cancer has metastasized. "To find the SLN, doctors inject radioactive particles and a blue dye into the breast. The lymphatic system gobbles up the injected material, treating it as foreign matter and accumulating it in the SLN. The radioactive particles can be detected using a Geiger counter held to the breast to locate the lymph nodes. Then, the doctors surgically open the breast, follow the blue dye, and dissect the SLN," Wang said.

Wang and Xia's technique allows the SLN to be imaged safely without radioactivity or surgery. A piece of tissue can then be removed using a minimally invasive needle biopsy and tested for cancer. "We will convert an invasive surgical procedure into a minimally invasive needle biopsy," Wang said.

In the future, they hope to attach molecules to the surface of the gold nanocages that will selectively bind to cancer cells, making a "smart contrast agent." Then, the nanocages will only be detected where cancer is present, eliminating the need for a needle biopsy.

Washington University in St. Louis

---

---

	Sentinel Lymph Node Biopsy by Hiram S. Cody III (Author), Harrison (Author), Serruys (Author), Erkinjuntti (Author), Schmidt (Author), Jones (Author), Barry M. Kinzbrunner (Author), Neil J. Weinreb (Author), Joel S. Policzer (Author), Giocobini (Author), Kopelman (Author) An intuitive and powerful technique, sentinel lymph node biopsy has entered clinical practice with astonishing rapidity and now represents a new standard of care for melanoma and breast cancer patients. It shows great promise for the treatment of urologic, colorectal, gynecologic, and head and neck cancers. This text, written by international experts in the technique, provides a clear and comprehensive guide. It discusses various mapping techniques and how these are applied in leading institutions. This essential resource for surgical oncologists, pathologists and specialists in nuclear medicine also provides key information for those planning to start a sentinel lymph node program.
	Biopsy Interpretation of Lymph Nodes (Biopsy Interpretation Series) by Steven H. Swerdlow (Author) This volume is a practical illustrated guide to the pathologic diagnosis of Hodgkin's disease, non-Hodgkin's lymphomas, and other diseases appearing in lymph node biopsies. Dr. Swerdlow's approach to lymph node diagnosis is grounded in a thorough knowledge of the varied ways in which lymphocytes can be charcterized. It provides a systematic approach to the diagnosis and classification of non-Hodgkin's lymphomas, based on the Lukes/Collins and Kiel classifications. Close attention is also given to accurated diagnosis of conditions other than lymphomas and to evaluation of entities that do not yet have well-defined histopathologic, immunophenotypic, or genotypic criteria.
	Lymph Node Biopsy by Harry L. Ioachim (Author)
	Ioachim's Lymph Node Pathology by Harry L. Ioachim (Editor), L. Jeffrey Medeiros (Editor) Now in its Fourth Edition, this comprehensive, practical, and thoroughly illustrated reference offers valuable guidance in the diagnostic interpretation of lymph node biopsies. It provides encyclopedic coverage of all the various nonmalignant lesions, lymphomas, other neoplasms, and metastatic tumors in lymph nodes. The discussion of each pathologic entity includes definition, clinical syndrome, histopathology, and differential diagnosis. This edition has more than 700 illustrations, including over 600 in full color. Dr. Ioachim is joined by a new co-editor, L. Jeffrey Medeiros, MD, from the University of Texas MD Anderson Cancer Center. All chapters have been extensively revised and a new chapter on genetics has been added. A companion Website will offer the fully searchable online text...
	Lymph Node Biopsy: A Diagnostic Atlas with 300 Photomicrographs in Full Colour by A.H.T. Robb-Smith (Author), C.R. Taylor (Author)
	Lymph Node Biopsy: A Diagnostic Atlas by A.H.J.Robb- Smith (Author), Clive R. Taylor (Author), A.H. Robb-Smith (Author)
	Lymph Node Biopsy Interpretation 2/E by A. G. Stansfeld (Author), Alfred G. Stansfeld (Editor), A. J. D'Ardenne (Editor) This offers diagnostic histopathologists practical guidelines for achieving optimal diagnostic accuracy in interpreting lymph node biopsies. Because this is a rapidly changing subject there is a large amount of new material in the second edition, including a new section on cytogenetics. There are also extensive appendices and illustrations.
	Gale Encyclopedia of Cancer: Lymph node biopsy by A.M. Tish Davidson (Author) The article is excerpted from Gale Encyclopedia of Cancer The resource students and researchers will turn to for reliable, up-to-date and clearly written information, the Gale Encyclopedia of Cancer is a comprehensive survey of 120 cancers, cancer drugs, traditional and alternative treatments and diagnostic procedures. The Encyclopedia includes entries covering cancers, cancer drugs, treatments, side effects and diagnostic procedures. Entries typically include the following elements: Causes and Symptoms Definition Description Diagnosis Prevention Resources Risks Special Concerns And more An appendix provides complete contact information for cancer centers, national support groups, government agencies and research groups. Features include anatomical...
	Gale Encyclopedia of Medicine: Lymph node biopsy by Tish Davidson A.M. (Author) The article is excerpted from Gale Encyclopedia of Medicine. Consult the second edition of this authoritative, comprehensive, in-depth medical guide for information on more than 1,700 medical topics in language accessible to adult laypersons. Presented in a single alphabetical sequence, articles range in length from one or two paragraphs for minor topics, to several pages or more for major topics. Disease/disorder articles typically cover definition; description; causes and symptoms; diagnosis; treatments; prevention; and more. Test/treatment articles typically cover definition; purposes; precautions; preparation; risks; normal and abnormal results; and much more. This second edition includes more than 200 new entries, 300 updated entries, approximately 650 color images...
	Should you perform sentinel lymph node biopsies for patients with primary cutaneous melanoma?(Pro & Con): An article from: Skin & Allergy News by Julian A. Kim (Author), A. Bernard Ackerman (Author) This digital document is an article from Skin & Allergy News, published by International Medical News Group on February 1, 2004. The length of the article is 1052 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Should you perform sentinel lymph node biopsies for patients with primary cutaneous melanoma?(Pro & Con) Author: Julian A. Kim Publication: Skin & Allergy News (Magazine/Journal) Date: February 1, 2004 Publisher: International Medical News Group Volume: 35 Issue: 2 Page: 14(1) Distributed by Thomson...