Deciphering the spectra of breast cancer in multispectral optoacoustic tomography

Multispectral optoacoustic tomography (MSOT) has been utilized to non-invasively resolve morphological changes like angiogenesis and metabolic parameters like hemoglobin concentration and oxygenation in breast tumors. Compared to other optical methods, MSOT provides higher spatial resolution, higher penetration depth and does not require the use of contrast agents. Thus, MSOT could aid the non-invasive diagnosis and treatment monitoring of breast cancer. Because MSOT illuminates tissue at multiple wavelengths, the acquired data contains spectral information about the chromophores contained in tissue. This spectral data may serve as additional dimension to infer cancer biomarkers. Recent advances in data processing and image reconstruction enable the spectroscopic analysis of MSOT data. However, effects like fluence attenuation and spectral coloring alter the spectral data hampering the identification of chromophores. Hence, it is necessary to analyze and understand spectral MSOT data—"MSOT spectra”—to not draw wrong conclusions. <br/> <br/> In this work, we showcase MSOT spectra of healthy and cancerous breast tissue in four patients between 680 nm and 1100 nm for the first time. We investigate trends and variations in MSOT spectra of tumor, tumor core, tumor rim, tumor perimeter and healthy background tissue with respect to different regions of interest and with respect to the tumors’ molecular subtypes. Moreover, we showcase effects of spectral coloring which are observed in the in-vivo MSOT spectra. <br/> <br/> Our work provides a new perspective on MSOT imaging of breast cancer. We lay the foundation to derive novel, spectral MSOT biomarkers of breast cancer aiding the clinical translation.