The status of the lymph nodes serves as the most important prognostic indicators for patients with breast carcinoma and provides one of the parameters that indicates the need for adjuvant treatment. Breast cancer patients with mammographically detected cancers first undergo diagnostic lymphoscintigraphy. Lymphoscintigraphy is typically performed using a radiocolloid as a nonspecific contrast agent injected peritumorally for nuclear imaging and localization of sentinel or closest lymph nodes for surgical resection and subsequent biopsy. The resection and biopsy of the sentinel rather than major lymph nodes minimize surgical evasiveness.
However, in breast cancer patients, lymphoscintigraphy is compromised by increased amounts of adipose tissue in obese subjects, where the sentinel lymph location can be as deep as 4 cm from the tissue surface. Nuclear imaging is also hampered by chemotherapy, which may shrink the size of the lymph node to as small as 5 mm. In addition, nuclear imaging may not provide adequate sentinel node detection because of slow and inconsistent drainage of radiopharmaceuticals through the lymphatic system.
U.S. Pat. No. 5,865,754 to Sevick-Muraca et al. describes a fluorescence imaging system that relates to in vivo imaging of biologic tissue by mapping a fluorescence characteristic of the tissue through the detection of light emitted in response to excitation light from a time-varying light source.