Purpose-To prospectively demonstrate the feasibility of using indocyanine green, a nearinfrared (NIR) fluorophore at the minimum dose needed for noninvasive optical imaging of lymph nodes (LNs) in breast cancer patients undergoing sentinel lymph node mapping (SLNM).Materials and Methods-Informed consent was obtained from 24 women (age range, 30-85 years) who received intradermal subcutaneous injections of 0.31-100 μg indocyanine green in the breast in this IRB-approved, HIPAA-compliant, dose escalation study to find the minimum microdose for imaging. The breast, axilla, and sternum were illuminated with NIR light and the fluorescence generated in the tissue was collected with an NIR-sensitive intensified chargedcoupled device. Lymphoscintigraphy was also performed. Resected LNs were evaluated for the presence of radioactivity, blue dye accumulation, and fluorescence. The associations between the resected LNs that were fluorescent and (a) the time elapsed between NIR fluorophore administration and resection and (b) the dosage of NIR fluorophores were tested with the Spearman rank and Pearson product moment correlation tests, respectively.Results-Lymph imaging consistently failed with indocyanine green microdosages between 0.31 and 0.77 μg. When indocyanine green dosages were 10 μg or higher, lymph drainage pathways from the injection site to LNs were imaged in eight of nine women; lymph propulsion was observed in seven of those eight. When propulsion in the breast and axilla regions was present, the mean apparent velocities ranged from 0.08 to 0.32 cm/sec, the time elapsed between "packets" of propelled fluid varied from 14 to 92 seconds. In patients who received 10 μg of indocyanine green or more, a weak negative correlation between the fluorescence status of resected LNs and the time © RSNA, 2008 Address correspondence to E.M.S. (evas@bcm.tmc.edu). Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2463070962/DC1 Author contributions:Guarantor of integrity of entire study, E.M.S.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, all authors; clinical studies, all authors; statistical analysis, all authors; and manuscript editing, all authors See Materials and Methods for pertinent disclosures. NIH Public Access Author ManuscriptRadiology. Author manuscript; available in PMC 2011 September 3. Conclusion-NIR fluorescence imaging of lymph function and LNs is feasible in humans at microdoses that would be needed for future molecular imaging of cancer-positive LNs.Currently, standard-of-care staging of breast cancer requires surgical resection of the first tumor-draining, or sentinel, lymph node (SLN) for subsequent pathologic examination (1). If the SLN is cancerous, then additional lymph nodes (LNs) in the axillary basin are subsequently removed for accurate staging. Recently, the a...

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SummaryWhile the lymphatic system is increasingly associated with diseases of prevalence, study of these diseases is difficult owing to the paucity of imaging techniques with the sensitivity and temporal resolution to discriminate lymphatic function. Herein, we review the known, pertinent features of the human lymphatic system in health and disease and set the context for a number of emerging studies that use near-infrared fluorescence imaging to non-invasively assess tumor draining lymphatic basins in cancer patients, intraoperatively guide resection of first draining lymph nodes, and to interrogate the difference between normal and aberrant lymphatic structure and function.

ObjectiveFluorophore-labeled contrast imaging agents are moving toward clinical use for a number of applications. The near-infrared dye IRDye 800CW is frequently used in its N-hydroxysuccinamide (NHS) ester form for labeling these agents. Following conjugation or breakdown of a labeled ligand, excess NHS ester is converted to the carboxylate form. To prepare for clinical use as a near-infrared fluorophore, a toxicity study was conducted on IRDye 800CW carboxylate.MethodsMale and female Sprague–Dawley rats were given a single intravenous or intradermal administration of IRDye 800CW carboxylate; Indocyanine Green was used as a comparative control. Animals were injected with varying doses of the test and control articles and observed for up to 14 days. Clinical chemistry, hematological, and pharmacokinetic analyses were performed on subgroups of animals. Organs were analyzed for content of the test article. Tissues were analyzed microscopically for pathological changes.ResultsBased on hematologic, clinical chemistry, and histopathologic evaluation, single administration of IRDye 800CW carboxylate intravenously at dose levels of 1, 5, and 20 mg/kg or 20 mg/kg intradermally produced no pathological evidence of toxicity.ConclusionA dose of 20 mg/kg was identified as the no observed adverse effect level following IV or ID routes of administration of IRDye 800CW.Electronic supplementary materialThe online version of this article (doi:10.1007/s11307-010-0317-x) contains supplementary material, which is available to authorized users.