Breast Cancer: Early- and Late-Fluorescence Near-Infrared Imaging with Indocyanine Green—A Preliminary Study

Abstract

To assess early- and late-fluorescence near-infrared imaging, corresponding to the vascular (early-fluorescence) and extravascular (late-fluorescence) phases of indocyanine green (ICG) enhancement, for breast cancer detection and benign versus malignant breast lesion differentiation. The study was approved by the ethical review board; all participants provided written informed consent. Twenty women with 21 breast lesions were examined with near-infrared imaging before, during, and after intravenous injection of ICG. Absorption and fluorescence projection mammograms were recorded simultaneously on a prototype near-infrared imaging unit. Two blinded readers independently assessed the images and assigned visibility scores to lesions seen on the absorption and absorption-corrected fluorescence mammograms. Imaging results were compared with histopathologic findings. Lesion contrast and diameter on the fluorescence mammograms were measured, and Cohen κ, Mann-Whitney U, and Spearman ρ tests were conducted. The absorption-corrected fluorescence ratio mammograms showed high contrast (contrast value range, 0.25-0.64) between tumors and surrounding breast tissue. Malignant lesions were correctly defined in 11 (reader 1) and 12 (reader 2) of 13 cases, and benign lesions were correctly defined in six (reader 1) and five (reader 2) of eight cases with late-fluorescence imaging. Lesion visibility scores for malignant and benign lesions were significantly different on the fluorescence ratio mammograms (P = .003) but not on the absorption mammograms (P = .206). Mean sensitivity and specificity reached 92% ± 8 (standard error of mean) and 75% ± 16, respectively, for fluorescence ratio imaging compared with 100% ± 0 and 25% ± 16, respectively, for conventional mammography alone. Preliminary data suggest that early- and late-fluorescence ratio imaging after ICG administration can be used to distinguish malignant from benign breast lesions.