Sunkuk Kwon, Abstract Co-Author: Nothing to Disclose

Sergy Lemeshko MD, PhD, Presenter: Nothing to Disclose

Wei Wang, Abstract Co-Author: Nothing to Disclose

Shi Ke, Abstract Co-Author: Nothing to Disclose

Devon Caywood, Abstract Co-Author: Nothing to Disclose

Michel E. Mawad MD, Abstract Co-Author: Nothing to Disclose

Eva M. Sevick-Muraca PhD, Abstract Co-Author: Research grant, Becton, Dickinson and Company

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Lymph node status serves as an important prognostic marker in melanoma as well as several other cancers. We hypothesize that intradermal administration of molecularly targeted imaging agents can provide diagnostic imaging for purposes of regional nodal staging. In this work. a preclinical model of human melanoma implanted in axilla lymph nodes of athymic mice was used to test a cyclic RGD peptide dual labeled for PET as well as for near infrared (NIR) optical imaging.

Human melanoma tumor cells positively expressing the αvβ3 integrin (M21) or not expressing the αvβ3 integrin (M21L) were inoculated directly into the axillary LN of animals (N=10) without interrupting lymphatic vessels. Normal saline was injected into the opposite side axillary LN as a control. Fluorescence and PET imaging were conducted at 20min, 6hr, and 18hr after intradermal injection of 61Cu-DOTA-IRDye800-c(KRGDf) in both footpads. The mean of the fluorescence intensities within each two-dimensional regions of interest (ROIs) were calculated. Three-dimensional ROIs were drawn over each ROI on decay-corrected whole-body PET images to obtain an imaging ROI-derived percent injected dose per gram.

The fluorescence and PET images at 20 min after agent administration showed that the signal associated with the axillary nodes was non-specific whether M21 cells, M21L cells, or saline were inoculated. However, at 6 and 18hr after injection, the signal remained only on the axillary node where αvβ3 positive M21 cells were inoculated. PET studies revealed that the uptake of 61Cu-DOTA-IRDye800-c(KRGDf) in M21 cells in the axillary node was significantly greater than in nodes injected with saline or M21L cells at 6 and 18 hrs after injection.

When administered intradermally, 61Cu-DOTA-IRDye800-c(KRGDf) specifically targets to αvβ3 integrin expressed in M21 cells implanted within the axillary node.

Regional, diagnostic imaging of lymph node status following intradermal administration of molecularly targeting PET/NIR agents could enable staging with greater efficacy and less morbidity.

Kwon, S, Lemeshko, S, Wang, W, Ke, S, Caywood, D, Mawad, M, Sevick-Muraca, E, et al, , et al, , Molecular Imaging of a Model of Melanoma Lymph Node Metastases.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014223.html