Fluorescence-enhanced absorption imaging using frequency-domain photon migration: tolerance to measurement error

Enhanced contrast of frequency-domain photon migration (FDPM) measurements for successful biomedical optical imaging may be theoretically achieved with exogenous fluorescence contrast agents. However in practice, the reduced fluorescence signals detected at the air-tissue interface possess significant noise when compared to the signals collected at the incident wavelength. In this study, we experimentally assess signal to noise ratios (SNRs) for FDPM measurements in homogeneous tissue-like scattering media which absorb and fluorescence. At 100 MHz, the SNR for our single-pixel FDPM signals at the incident wavelength is approximately constant at 55 dB while the corresponding fluorescence signal SNR is variable with signal power and is approximately 35 dB. Using these SNR values to guide our studies on the tolerance of absorption and fluorescence-enhanced absorption imaging, we show that the noise tolerance of a Born iterative method for reconstruction of absorption from FDPM measurements at the incident wavelength cannot handle the reduced SNR that is tolerated by a Born iterative type approach for reconstruction of absorption from measurements at the emission wavelength.