Micrometastases Visible When SPECT/CT and Fluorescent Imaging Used Together

Pulmonary micrometastases of colorectal cancer are detectable far earlier with combination imaging, opening door to improved cancer treatment.

SPECT/CT used with fluorescence could help surgeons tell the difference between tumor tissue and normal tissue, according to a new study from The Netherlands. In a study, published in The Journal of Nuclear Medicine, researchers analyzed data on colorectal cancer that had metastasized beyond the primary tumor. Using a mouse model, investigators identified pulmonary micromestastases of colorectal cancer with labetuzumab, an antibody that targets carcinoembryonic antigen. It was labeled with both a near-infrared fluorescent dye (IRDye800CW) and radioactive Indium-111. Carcinoembryonic antigen is overexpressed in 95% of colorectal cancer cases.  Using micro-SPECT and fluorescence imaging, from the first week of tumor growth, researchers visualized sub-millimeter pulmonary tumor colonies. Results also indicated dual-modality imaging can also guide tumor lesion resection which is critical for patients to achieve the best prognosis.  An injection of Indium-111-DTPA-labetuzumab-IRDye800CW enables detection of tiny carcinoembryonic antigen. The same strategy, with a different tumor-targeting antibody, can also be used with other types of cancer, researchers said.  Ultimately, study results demonstrate the possibility to detect micrometastases of colorectal cancer with fluorescence imaging and SPECT/CT before they're visible to the naked eye, and the broad application of the strategy could change oncology surgery and improve cancer patient prognoses.