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99mTc-Labeled Superparamagnetic Iron Oxide Nanoparticles for Multimodality SPECT/MRI of Sentinel Lymph Nodes.

Author:
  • Renata Madru
  • Pontus Kjellman
  • Fredrik Olsson
  • Karin Wingårdh
  • Christian Ingvar
  • Freddy Ståhlberg
  • Johan Olsrud
  • Jimmy Lätt
  • Sarah Fredriksson
  • Linda Knutsson
  • Sven-Erik Strand
Publishing year: 2012
Language: English
Pages: 459-463
Publication/Series: Journal of Nuclear Medicine
Volume: 53
Issue: 3
Document type: Journal article
Publisher: Society of Nuclear Medicine

Abstract english

The purpose of this study was to develop multimodality SPECT/MRI contrast agents for sentinel lymph node (SLN) mapping in vivo. METHODS: Nanoparticles with a solid iron oxide core and a polyethylene glycol coating were labeled with (99m)Tc. The labeling efficiency was determined with instant thin-layer chromatography and magnetic separation. The stability of the radiolabeled superparamagnetic iron oxide nanoparticles (SPIONs) was verified in both sterile water and human serum at room temperature 6 and 24 h after labeling. Five Wistar rats were injected subcutaneously in the right hind paw with (99m)Tc-SPIONs (25-50 MBq, ∼0.2 mg of Fe) and sacrificed 4 h after injection. Two animals were imaged with SPECT/MRI. All 5 rats were dissected; the lymph nodes, liver, kidneys, spleen, and hind paw containing the injection site were removed and weighed; and activity in the samples was measured. The microdistribution within the lymph nodes was studied with digital autoradiography. RESULTS: The efficiency of labeling of the SPIONs was 99% 6 h after labeling in both water and human serum. The labeling yield was 98% in water and 97% in human serum 24 h after labeling. The SLN could be identified in vivo with SPECT/MRI. The accumulation of (99m)Tc-SPIONs (as the percentage injected dose/g [%ID/g]) in the SLN was 100 %ID/g, whereas in the liver and spleen it was less than 2 %ID/g. Digital autoradiography images revealed a nonhomogeneous distribution of (99m)Tc-SPIONs within the lymph nodes; nanoparticles were found in the cortical, subcapsular, and medullary sinuses. CONCLUSION: This study revealed the feasibility of labeling SPIONs with (99m)Tc. The accumulation of (99m)Tc-SPIONs in lymph nodes after subcutaneous injection in animals, verified by SPECT/MRI, is encouraging for applications in breast cancer and malignant melanoma.

Keywords

  • Radiology, Nuclear Medicine and Medical Imaging
  • Tc-99m
  • lymph nodes
  • SPECT/MRI
  • nanoparticles
  • iron oxide
  • SPIONs

Other

Published
  • ISSN: 0161-5505
Sven-Erik Strand
E-mail: sven-erik [dot] strand [at] med [dot] lu [dot] se

Project manager

Systemic Radiation Therapy Group

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Professor emeritus

Medical Radiation Physics, Lund

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