Investigation of effect of modulation frequency on high-density diffuse optical tomography image quality

Fan, Weihao; Dehghani, Hamid; Eggebrecht, Adam T.

doi:10.1117/1.nph.8.4.045002

Cited by 22 publications

(8 citation statements)

References 71 publications

(115 reference statements)

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“…There is an upward tail to the reconstruction of the contrast anomaly which extends to the surface of the phantom from the CW case, which is not observed for the FD or mFD case. As is previously established, phase data samples deeper than intensity data [ 14 , 26 ] , which are evident in the FD and mFD reconstruction of absorption coefficient. However, the FD and mFD reconstructions suffer from some positive and negative contrast artifacts, which are seen above the contrast anomaly instead of the positive tail in the CW case.…”

Section: Discussionmentioning

confidence: 97%

“…The reason why intensity data at multiple modulation frequencies was not in the mFD data type was that it has been shown that there is an appreciable increase in the sampling depth of phase data for increasing modulation frequencies, but that the change in sampling depth with intensity data is very small [ 26 ], so it was decided that only additional phases would be used in the mFD data.…”

Section: Methodsmentioning

confidence: 99%

“…The final two simulation studies also in 2021 were from DeJong et al [ 25 ] and Fan et al [ 26 ], where they both use 3D atlas models of the human adult head for HD-DOT, with Fan using 5 different head models. Fan uses 11 frequencies between 0 to 1000 MHz and found that without noise 700 MHz gave the most accurate localization of brain activations and 1000 MHz the lowest full width half maximum error in reconstruction of optical properties.…”

Section: Introductionmentioning

confidence: 99%

“…Quantitative evaluations of how mFD-HD-DOT measurements perform have only been simulated Perkins et al [ 24 ], DeJong et al [ 25 ] and Fan et al [ 26 ]), so evaluating the performance of mFD on a phantom will eliminate factors which can effect the measurement outside of type of data itself, such as poor source-detector coupling and instrumental noise. As well as this, it allows for flexibility in the processing of data and methods for image reconstruction, due to the simple geometry and stable measurements on a phantom.…”

Section: Introductionmentioning

confidence: 99%

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Multi-modulated frequency domain high density diffuse optical tomography

Perkins

Eggebrecht²,

Dehghani³

2022

Biomed. Opt. Express

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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.

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Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-modulated frequency domain high density diffuse optical tomography

Perkins

Eggebrecht²,

Dehghani³

2022

Biomed. Opt. Express

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“…Although alternative fNIRS acquisition techniques, such as TD fNIRS and FD (frequency domain) fNIRS, 23 offer many theoretical advantages over the more traditionally used CW fNIRS (including enhanced sensitivity to deeper tissue 24 , 25 ), several practical aspects have hindered their adoption. In particular, TD and FD fNIRS require much more complicated and precise (and thus, potentially more expensive) instrumentation, as well as more sophisticated processing techniques to reach their full potential.…”

Section: Discussionmentioning

confidence: 99%

How much do time-domain functional near-infrared spectroscopy (fNIRS) moments improve estimation of brain activity over traditional fNIRS?

et al. 2022

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. Significance Advances in electronics have allowed the recent development of compact, high channel count time domain functional near-infrared spectroscopy (TD-fNIRS) systems. Temporal moment analysis has been proposed for increased brain sensitivity due to the depth selectivity of higher order temporal moments. We propose a general linear model (GLM) incorporating TD moment data and auxiliary physiological measurements, such as short separation channels, to improve the recovery of the HRF. Aims We compare the performance of previously reported multi-distance TD moment techniques to commonly used techniques for continuous wave (CW) fNIRS hemodynamic response function (HRF) recovery, namely block averaging and CW GLM. Additionally, we compare the multi-distance TD moment technique to TD moment GLM. Approach We augmented resting TD-fNIRS moment data (six subjects) with known synthetic HRFs. We then employed block averaging and GLM techniques with “short-separation regression” designed both for CW and TD to recover the HRFs. We calculated the root mean square error (RMSE) and the correlation of the recovered HRF to the ground truth. We compared the performance of equivalent CW and TD techniques with paired t-tests. Results We found that, on average, TD moment HRF recovery improves correlations by 98% and 48% for HbO and HbR respectively, over CW GLM. The improvement on the correlation for TD GLM over TD moment is 12% (HbO) and 27% (HbR). RMSE decreases 56% and 52% (HbO and HbR) for TD moment compared to CW GLM. We found no statistically significant improvement in the RMSE for TD GLM compared to TD moment. Conclusions Properly covariance-scaled TD moment techniques outperform their CW equivalents in both RMSE and correlation in the recovery of the synthetic HRFs. Furthermore, our proposed TD GLM based on moments outperforms regular TD moment analysis, while allowing the incorporation of auxiliary measurements of the confounding physiological signals from the scalp.

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Fundamental effects of array density and modulation frequency on image quality of diffuse optical tomography

Fan,

Trobaugh,

Zhang

et al. 2024

Medical Physics

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BackgroundDiffuse optical tomography (DOT) provides three‐dimensional image reconstruction of chromophore perturbations within a turbid volume. Two leading strategies to optimize DOT image quality include, (i) arrays of regular, interlacing, high‐density (HD) grids of sources and detectors with closest spacing less than 15 mm, or (ii) source modulated light of order ∼100 MHz.PurposeHowever, the general principles for how these crucial design parameters of array density and modulation frequency may interact to provide an optimal system design have yet to be elucidated.MethodsHerein, we systematically evaluated how these design parameters effect image quality via multiple key metrics. Specifically, we simulated 32 system designs with realistic measurement noise and quantified localization error, spatial resolution, signal‐to‐noise, and localization depth of field for each of ∼85 000 point spread functions in each model.ResultsWe found that array density had a far stronger effect on image quality metrics than modulation frequency. Additionally, model fits for image quality metrics revealed that potential improvements diminish with regular arrays denser than 9 mm closest spacing. Further, for a given array density, 300 MHz source modulation provided the deepest reliable imaging compared to other frequencies.ConclusionsOur results indicate that both array density and modulation frequency affect the spatial sampling of tissue, which asymptotically saturates due to photon diffusivity within a turbid volume. In summary, our results provide comprehensive perspectives for optimizing future DOT system designs in applications from wearable functional brain imaging to breast tumor detection.

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Investigation of effect of modulation frequency on high-density diffuse optical tomography image quality

Cited by 22 publications

References 71 publications

Multi-modulated frequency domain high density diffuse optical tomography

Multi-modulated frequency domain high density diffuse optical tomography

How much do time-domain functional near-infrared spectroscopy (fNIRS) moments improve estimation of brain activity over traditional fNIRS?

Fundamental effects of array density and modulation frequency on image quality of diffuse optical tomography

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