Delivery of gadolinium-labeled nanoparticles to the sentinel lymph node: comparison of the sentinel node visualization and estimations of intra-nodal gadolinium concentration by the magnetic resonance imaging.

Abstract

Sentinel node imaging is commonly performed prior to surgery for breast cancer and melanoma. While current methods are based on radio-lymphoscintigraphy, MR lymphangiography (MRL) offers the benefits of better spatial resolution without ionizing radiation. However, the optimal nanoparticle for imaging the sentinel nodes remains unclear. Gadolinium-labeled (Gd) contrast agents ranging in diameter from <1 to 12 nm were evaluated to determine which size provides the most rapid and most concentrated delivery of contrast agent to the lymph nodes in a mouse model of lymphatic metastases. Specifically, PAMAM-G2, -G4, -G6 and -G8, and DAB-G5 Gd-dendrimer agents, as well as Gadomer-17 and Gd-DTPA, were compared. Among these agents, the G6 Gd dendrimer depicted the lymphatics and lymph nodes with the highest peak concentrations and this occurred 24-36 min post-injection (p<0.01; all except G8). Based on ex vivo concentration phantoms, high accumulations of Gd(III) ions occurred within lymph nodes (1.7-4.4 mM Gd/270-680 ppm Gd) with high target to background ratios (>100). These concentrations are sufficient to contemplate the use of Gd-neutron capture therapy of regional lymph nodes. Thus, when injected interstitially, the PAMAM-G6 Gd dendrimer not only provides excellent opacification of sentinel lymph nodes, but also provides the potential for targeted therapy of sentinel lymph nodes.

• Authors: Hisataka Kobayashi, Satomi Kawamoto, Marcelino Bernardo, Martin W Brechbiel, Michael V Knopp, Peter L Choyke
• Journal: Journal of controlled release : official journal of the Controlled Release Society (J Control Release) Vol. 111 Issue 3 Pg. 343-51 (Apr 10 2006) ISSN: 0168-3659 [Print] Netherlands
• PMID: 16490277 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)

Chemical References

• Contrast Media
• Dendrimers
• PAMAM Starburst
• Polyamines
• Gadolinium

Topics

• Animals
• Contrast Media (chemistry)
• Dendrimers
• Female
• Gadolinium (analysis)
• Lymph Nodes (metabolism)
• Lymphatic Metastasis
• Magnetic Resonance Imaging
• Mammary Neoplasms, Experimental (diagnosis, radiotherapy)
• Mice
• Models, Animal
• Nanoparticles
• Neutron Capture Therapy
• Polyamines (chemistry)