Editors' ChoiceBiomedical Imaging

Breast Cancer Imaging Goes Green

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Science Translational Medicine  20 Apr 2011:
Vol. 3, Issue 79, pp. 79ec58
DOI: 10.1126/scitranslmed.3002510

Going green may be a concept that even mammographers can buy into. As shown by Poellinger et al., indocyanine green (ICG) combined with near-infrared (NIR) imaging might be just the right tool to complement conventional breast cancer screening. X-ray mammography is the accepted screening method for the detection of breast cancer lesions but often requires additional tests, such as magnetic resonance imaging (MRI), to determine whether these lesions have malignant potential. NIR imaging is being approached as a potential cheaper alternative to MRI.

ICG, a weak fluorescent dye, does not readily leak out of normal vessels because it binds avidly to serum proteins. However, vessels around tumors might be porous enough to allow serum proteins (along with ICG) to leak into surrounding tissue, thus providing an intense contrast between tumor and nontumor lesions. Poellinger and colleagues evaluated the use of intravenously injected ICG with NIR imaging to determine whether this method could be used to differentiate between benign and malignant breast masses that had been detected on mammography and ultrasound screens. Twenty women between the ages of 40 and 80, who altogether had 21 suspicious breast lesions, were selected for the study. The women were imaged both before and after ICG injection, using a 790-nm laser for dye excitation. Post-injection images were obtained when the arterial ICG concentration reached steady-state, and also at a delayed timepoint, when the arterial ICG concentration had dropped to pre-injection levels.

The authors then generated laser absorption mammograms and fluorescence ratio images. Two blinded readers evaluated the resulting images and scored the lesions as either benign or malignant. These “scores” were either confirmed or rejected by histopathological analysis. Compared with conventional mammography scoring, the sensitivity for lesion detection was slightly lower (92% versus 100%), but the specificity in discrimination between benign and malignant lesions was much higher (75% versus 25%). The dramatically better contrast between normal and malignant breast lesions using ICG could complement conventional mammography and help avoid costly false-positive readings, thus giving physicians yet another reason to “go green.”

A. Poellinger et al., Breast cancer: Early- and late-fluorescence near-infrared imaging with indocyanine green—A preliminary study. Radiology 258, 409–416 (2011). [PubMed]

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