Photoacoustic imaging (PAI) technology, one of the most rapidly growing areas in medical imaging in the last decade, shows great potential for improved diagnosis, monitoring, and treatment of many diseases. However, because of the limited bandwidth in photoacoustic (PA) signal detection, and the uncertainty of light fluence in tissue, conventional PAI images remain largely qualitative. Moreover, PAI findings are highly dependent on the individual system and operator, and hence, are difficult to be reproduced and used for purposes of objective comparison. Ultrasound (US) spectrum analysis (USSA) has shown potential for evaluating several parameters (such as dimension and density) of microscopic backscatters in biologic tissues. USSA, however, is a purely “physical” imaging technique due to its mono-physics nature. Due to the physical-limiting nature of PAI and the chemical-limiting nature of USSA, there remains a need to develop an imaging system that can analyze both physical and chemical biological structures simultaneously.
The present technology provides for a method of assessing physical and chemical biomarkers in a tissue. The method includes performing a photoacoustic scan by illuminating the tissue to generate acoustic signals and detecting the acoustic signals generated from the tissue. The method also includes transforming the acoustic signals into a plurality of frequency domains to create a plurality of power spectra and generating a two dimensional physio-chemical spectrogram (PCS) from the plurality of power spectra acquired from the photoacoustic scan. Additionally, the present technology provides for a method of performing photoacoustic physio-chemical analysis (PAPCA) on a tissue. The method includes performing a plurality of photoacoustic scans on a tissue to generate photoacoustic signals, wherein each scan comprises a broad range of wavelengths. The method further includes transforming the photoacoustic signal at each wavelength into a frequency domain to create power spectra, and generating a two dimensional physio-chemical spectrogram (PCS) from the power spectra. The PCS comprises a first axis representing an optical wavelength and a second axis representing ultrasonic frequency. The axis presenting the optical wavelength indicates the chemical components in the tissue. The ultrasonic frequency indicates the micron scale tissue features, such as whether the tissue is homogeneous or heterogeneous. The PCS provides physical and chemical information about the tissue simultaneously, which can be used to diagnosis diseases.