Multi-modulated frequency domain high density diffuse optical tomography

Frequency domain (FD) high density diffuse optical tomography (HD-DOT) utilising varying or combined modulation frequencies (mFD) has shown to theoretically improve the imaging accuracy as compared to conventional continuous wave (CW) measurements. Using intensity and phase data from a solid inhomogeneous phantom (NEUROPT) with three insertable rods containing different contrast anomalies, at modulation frequencies of 78 MHz, 141 MHz and 203 MHz, HD-DOT is applied and quantitatively evaluated, showing that mFD outperforms FD and CW for both absolute (iterative) and temporal (linear) tomographic imaging. The localization error (LOCA), full width half maximum (FWHM) and effective resolution (ERES) were evaluated. Across all rods, the LOCA of mFD was 61.3% better than FD and 106.1% better than CW. For FWHM, CW was 6.0% better than FD and mFD and for ERES, mFD was 1.20% better than FD and 9.83% better than CW. Using mFD data is shown to minimize the effect of inherently noisier FD phase data whilst maximising its strengths through improved contrast.

Automated summary

Frequency domain high density diffuse optical tomography (HD-DOT) using varying or combined modulation frequencies (mFD) has been shown to improve imaging accuracy compared to conventional continuous wave (CW) measurements. In this study, the performance of mFD was evaluated using intensity and phase data from a solid inhomogeneous phantom with contrast anomalies. The results demonstrate that mFD outperforms both FD and CW in terms of absolute and temporal tomographic imaging. The utilization of mFD data minimizes the impact of noisy FD phase data and maximizes the strengths of FD through improved contrast.