The use of protein-based radiocolloids in sentinel node localisation

James R. Ballinger*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

13 Citations (Scopus)

Abstract

Although lymphoscintigraphy has been part of nuclear medicine since the earliest days, the scintigraphic sentinel node procedure is only about 20 years old. During that time, it has gradually become the standard of care in an increasing range of cancers. Despite sentinel node procedures being carried out around the world, there is no consensus on the optimal properties or composition of the radiotracer, with the prime determinant of choice being geography: filtered sulphide colloid being used in the United States, antimony sulphide colloid in Australia and Canada, and protein-based radiocolloids in Europe. Ideal properties of a 99mTc-labelled protein colloid for sentinel node localisation include rapid transit from the injection depot to the sentinel node and prolonged retention in the node. The agents in clinical use offer a balance between these two conflicting properties. This review assesses the available evidence on the role of colloidal particle size on efficacy of sentinel node localisation. It has been suggested that the optimal particle size is 100–200 nm, but most of the radiocolloids in clinical use are smaller than this. The amount of activity to be administered varies between types of cancer and as a function of time between injection and surgery. Another parameter upon which there is disagreement is the number of particles administered. Traditionally the sentinel node procedure has been performed with separate injections of radiocolloid and blue dye (often separated in time), as the combination of two means of detection (radioactivity and visual) has better sensitivity than either modality alone. Recently, convenient methods have been developed to attach a fluorescent label to colloidal protein, such that the radioactivity and optical signal come from the same molecule given at a single injection time. Preliminary results have been promising and agents with improved properties are being developed. Finally, we have recently seen the introduction of the first tracer specifically designed for sentinel node localisation, the non-colloidal macromolecule tilmanocept. It remains to be seen where its role will be in sentinel node localisation.

Original languageEnglish
Pages (from-to)179-186
Number of pages8
JournalClinical and Translational Imaging
Volume3
Issue number3
DOIs
Publication statusPublished - 29 Jun 2015

Keywords

  • Nanocolloid
  • Protein-based radiocolloid
  • Sentinel node
  • Technetium-99m

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