Near infrared (NIR) fluorescence imaging is an emerging modality that can enable real-time image-guided procedures. Indocyanine green (ICG) is an FDA-approved, inexpensive, and widely available NIR dye. We hypothesized that axillary lymphatic mapping with ICG is equivalent to lymphatic mapping with technetium 99m (^99mTc) in breast cancer patients.

Breast cancer patients (cT1-2, N0) were prospectively enrolled. Patients underwent lymphatic mapping with ^99mTc preoperatively and ICG mapping intraoperatively (0.8 mL). Sentinel lymph node (SLN) biopsy was guided by NIR camera and gamma probe. Rate of failed mapping, number of SLNs identified, and rate of identifying pathologically positive SLNs were compared between the 2 techniques (p < 0.05 was considered statistically significant).

Ninety-two female patients were enrolled (median age 59 years). Mean transit time from ICG injection in the breast to localization in the axilla was 5 minutes (range 2 to 29 minutes). No adverse reactions to ICG were noted. Mean number of SLNs identified with ICG and ^99mTc was 2.4 (SD 1.42) and 2.2 (SD 1.23), respectively (p = 0.34). Pathologically positive SLNs were identified in 18 (19.8%) patients. A total of 24 pathologically positive SLNs in 18 patients were identified by ICG in 24 of 24 (100%) patients and by ^99mTc in 23 of 24 (96%) patients (p = 0.99).

Indocyanine green with NIR fluorescence imaging can be safely and efficiently used for real-time intraoperative lymphatic mapping in breast cancer patients. Indocyanine green performs similarly to ^99mTc with regard to the number of SLNs identified, rate of failed mapping, and identification of pathologically positive SLNs.