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Transformational change in the field of diffuse optics:From going bananas to going nuts

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Journal of Innovative Optical Health Sciences 2020年第1期3卷 1-18页

作者： Sergio Fantini Giles Blaney an.elo sassaroli Department of Biomedical Engineering Tufts University 4 Colby Street MedfordMA 02155USA

The concept of region of sensitivity is central to the field of diffuse optics and is closely related to the Jacobian matrix used to solve the inverse problem in *** is well known that,in diffuse reflectance,the region of sensitivity associated with a given source-detector pair is shaped as a banana,and features maximal sensitivity to the portions of the sample that are closest to the source and the *** have recently introduced a dual-slope(DS)method based on a special arrangement of two sources and two detectors,which results in deeper and more localized regions of sensitivity,resembling the shapes of different kinds of ***,we report the regions of sensitivity associated with a variety of source-detector arrangements for DS measurements of intensity and phase with frequency-domain spectroscopy(modulation frequency:140 MHz)in a medium with absorption and reduced scattering coefficients of 0.1 and 12 cm^(-1),*** main result is that the depth of maximum sensitivity,considering only cases that use source-detector separations of 25 and 35 mm,progressively increases as we consider single-distance intensity(2.0mm),DS intensity(4.6mm),single-distance phase(7.5mm),and DS phase(10.9 mm).These results indicate the importance of DS measurements,and even more so of phase measurements,when it is desirable to selectively probe deeper portions of a sample with diffuse *** is certainly the case in non-invasive optical studies of brain,muscle,and breast tissue,which are located underneath the superficial tissue at variable depths.

关键词： Near-infrared spectroscopy tissue optics diffuse optical tomography frequency domain dual slopes

Study of capillary transit time distribution in coherent hemodynamics spectroscopy

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Journal of Innovative Optical Health Sciences 2015年第2期8卷 78-86页

作者： an.elo sassaroli Jana Kainerstorfer Sergio Fantini Department of Biomedical Engineering Tufts University 4 Colby StreetMedfordMA 02155USA

A recently proposed analytical hemodynamie modell[***,Neurolmage 85,202-221(2014)]is able to predict the changes of oxy,deoxy,and total hemoglobin concentrations(model outputs)given arbitrary changes in blood flow,blood volume,and rate of oygen consumption(model inputs).One asumption of this model is that the capillary compartment is characterized by a single blood transit *** this work,we have extended the original model by considering a distribution of capillary transit times and we have compared the outputs of both models(original and extended)for the case of sinusoidal input signals at different frequencies,which realizes the new technique of coherent hemodynamics spectroscopy(CHS).For the calculations with the original model,we have used the mean value of the distribution of capillary transit times con-sidered in the extended *** have found that,for distributions of capillary transit times having mean values around 1 s and a standard deviation less than about 45%of the mean value,the original and extended models yield the same CHS spectra(i.e.,model outputs versus fre-quency of ocillation)within typical experimental *** wider capillary transit time dis-tributions,the two models yield different CHS *** assuming that Poiseuille's law is valid in the capillary compartment,we have related the distribution of capillary transit times to the distributions of capillary lengths and capillary speed of blood flow to calculate the average capillary and venous *** have found that,for standard deviations of the capillanry transit time distrilbution that are less than about 80%of the mean value,the average capillary saturation is always larger than the venous *** contrast,the average capillary satu-ration may be less than the venous saturation for wider distributions of the capillary transit times.

关键词： Coherent hemodynamics spectroscopy hermodynamie model near-infrared spectros-copy capillary transit time hemoglobin saturation

PHASE DIFFERENCE BETWEEN LOW-FREQUENCY OSCILLATIONS OF CEREBRAL DEOXY-AND OXY-HEMOGLOBIN CONCENTRATIONS DURING A MENTAL TASK

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Journal of Innovative Optical Health Sciences 2011年第2期4卷 151-158页

作者： an.elo sassaroli FENG ZHENG MICHELE PIERRO PETER R.BERGETHON SERGIO FANTINI Department of Biomedical Engineering Tufts University 4 Colby StreetMedfordMA 02155USA

Hemodynamic low-frequency(~0.1 Hz)spontaneous oscillations as detected in the brain by nearinfrared spectroscopy have potential applications in the study of brain activation,cerebral autoregulation,and functional *** this work,we have investigated the phase lag between oscillations of cerebral deoxy-and oxy-hemoglobin concentrations in the frequency range 0.05-0.10 Hz in a human subject during a mental workload *** have obtained a measure of such phase lag using two different methods:(1)phase synchronization analysis as used in the theory of chaotic oscillators and(2)a novel cross-correlation phasor *** two methods yielded comparable initial results of a larger phase lag between low-frequency oscillations of deoxy-and oxyhemoglobin concentrations during mental workload with respect to a control,rest condition.

关键词： Phase lag oxyhemoglobin deoxyhemoglobin phase synchronization cross-correlation phasor LFO

COHERENT HEMODYNAMICS SPECTROSCOPY BASED ON A PACED BREATHING PARADIGM-REVISITED

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Journal of Innovative Optical Health Sciences 2014年第1期7卷 91-99页

作者： JANA M.KAINERSTORFER an.elo sassaroli MICHELE L.PIERRO BERTAN HALLACOGLU SER.GIO FANTINI Department of Biomedical Engineering Tufts University 4 ColbyStreetMedfordMA 02155USA

A novel hemodynamic model has been recently introduced,which provides analytical relation-ships between the changes in cerebral blood volume(CBV),cerebral blood flow(CBF),andcerebral metabolic rate of oxy gen(CMRO2),and associat ed changes in the tissue concentrationsof oxy-and deoxy-hemoglobin(AO and AD)measured with near-infrared,spectroscopy(NIRS)[***,Neuroimage 85,202-221(2014)].This novel model can be applied tomeasurements of the amplit ude and phase of induced hemodynamic oscillations as a function ofthe frequency of oscillation,realizing the novel technique of coherent hemodynamics spectroscopy(CHS)[***,Neuroimage 85,202-221(2014);*** et al.,Neuroimage 85,222-233(2014)]:In a previous work,,we have demonstrated an in vivo application of CiHS on hunanSubjects during paced breat hing[*** et al,Neuroimage 85,222-233(2014)].In thiswork,we present a new analysis of the collected data duringpaced breat hing based on a slightlyrevised formulation of the hemodynamic model and ann efficient fitting *** we haveinitially treated all 12 model parameindeependent,we have found that,in this new in-plementation of CHS,the number of independent is *** this article,we identifythe eight independent model parameters and,we show that our previous results are consistentwith the new formulation,once the individual parameters of the earlier analysis are combinedinto the new set of independent parameters.

关键词： Hemodynamic model near-infrared spectroscopy cerebral autoregulation cerebralblood flow metabolic rate of oxygen.

NEAR-INFRARED,BROAD-BAND SPECTRAL IMAGING OF THE HUMAN BREAST FOR QUANTITATIVE OXIMETRY:APPLICATIONS TO HEALTHY AND CANCEROUS BREASTS

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Journal of Innovative Optical Health Sciences 2010年第4期3卷 267-277页

作者： YANG YU an.elo sassaroli DEBBIE K.CHEN MARC J.HOMER ROGER A.GRAHAM SERGIO FANTINI Department of Biomedical Engineering Tufts University 4 Colby StreetMedfordMA 02155USA Tufts Medical Center Department of Radiology 800 Washington StreetBostonMA 02111USA Tufts Medical Center Department of Surgery 800 Washington StreetBostonMA 02111USA

We have examined ten human subjects with a previously developed instrument for near-infrared diffuse spectral imaging of the female *** instrument is based on a tandem,planar scan of two collinear optical fibers(one for illumination and one for collection)to image a gently compressed breast in a transmission *** optical data collection features a spatial sampling of 25 points/cm2 over the whole breast,and a spectral sampling of 2 points/nm in the 650-900nm wavelength *** the ten human subjects examined,eight are healthy subjects and two are cancer patients with unilateral invasive ductal carcinoma and ductal carcinoma in situ,*** each subject,we generate second-derivative images that identify a network of highly absorbing structures in the breast that we assign to blood vessels.A previously developed paired-wavelength spectral method assigns oxygenation values to the absorbing structures displayed in the second-derivative *** resulting oxygenation images feature average values over the whole breast that are significantly lower in cancerous breasts(69±14%,n=2)than in healthy breasts(85±7%,n=18)(p<0.01).Furthermore,in the two patients with breast cancer,the average oxygenation values in the cancerous regions are also significantly lower than in the remainder of the breast(invasive ductal carcinoma:49±11%vs 61±16%,p<0.01;ductal carcinoma in situ:58±8%vs 77±11%,p<0.001).

关键词： Diffuse spectral imaging near-infrared spectroscopy optical mammography oximetry hemoglobin saturation

DISCRIMINATION OF MENTAL WORKLOAD LEVELS IN HUMAN SUBJECTS WITH FUNCTIONAL NEAR-INFRARED SPECTROSCOPY

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Journal of Innovative Optical Health Sciences 2008年第2期1卷 227-237页

作者： an.elo sassaroli FENG ZHENG LEANNE M.HIRSHFIELD AUDREY GIROUARD ERIN TREACY SOLOVEY ROBERT J.K.JACOB SERGIO FANTINI Department of Biomedical Engineering Tufts University MedfordMA 02155USA†Department of Computer Science Tufts UniversityMedfordMA 02155USA

We have applied functional near-infrared spectroscopy(fNIRS)to the human forehead to distinguish different levels of mental workload on the basis of hemodynamic changes occurring in the prefrontal *** report data on 3 subjects from a protocol involving 3 mental workload levels based on to working memory *** quantify the potential of fNIRS for mental workload discrimination,we have applied a 3-nearest neighbor classification algorithm based on the amplitude of oxyhemoglobin(HbO2)and deoxyhemoglobin(HbR)concentration changes associated with the working memory *** have found classification success rates in the range of 44%-72%,which are significantly higher than the corresponding chance level(for random data)of 19.1%.This work shows the potential of fNIRS for mental workload classification,especially when more parameters(rather than just the amplitude of concentration changes used here)and more sophisticated classification algorithms(rather than the simple 3-nearest neighbor algorithm used here)are considered and optimized for this application.

关键词： Diffuse optical imaging near-infrared spectroscopy functional brain imaging working memory mental workload

Role of rumination in the relationship between metacognition and shyness

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World Journal of Psychiatry 2018年第4期8卷 108-113页

作者： Sara Palmieri Giovanni Mansueto Simona Scaini Francesca Fiore Sandra sassaroli Giovanni M Ruggiero Rosita Borlimi Bernardo J Carducci Studi Cognitivi Cognitive Psychotherapy School and Research Center Department of Psychology Sigmund Freud University Psicoterapia Cognitiva e Ricerca Cognitive Psychotherapy School Shyness Research Institute Indiana University Southeast

AIM To explore the association between metacognitive beliefs, rumination and shyness in a non-clinical sample of adults. METHODS One hundred and three healthy subjects from the general population were enrolled in the study. Shyness was evaluated using the Revised Cheek and Buss Shyness Scale, rumination was assessed using the Ruminative Response Scale, metacognition was evaluated using the MetaCognitions Questionnaire 30, and anxiety levels were measured using the State Trait Anxiety Inventory form Y. Correlation analyses, mediation models and 95% bias-corrected and accelerated(BCaCI) bootstrapped analyses were performed. Mediation analyses were adjusted for sex and anxiety. RESULTS Shyness, rumination and metacognition were significantly correlated(P < 0.05). The relationship between metacognition and shyness was fully mediated by rumination(Indirect effect: 0.20; 95% BCaCI: 0.08-0.33).CONCLUSION These findings suggest an association between metacognition and shyness. Rumination mediated the relationship between metacognition and shyness, suggesting that rumination could be a cognitive strategy for shy people. Future research should explore the relationship between these constructs in more depth.

关键词： Social anxiety Shyness Rumination Postevent Metacognitive beliefs

Broadband diffuse optical spectroscopy of two-layered scattering media containing oxyhemoglobin,deoxyhemoglobin,water,and lipids

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Journal of Innovative Optical Health Sciences 2022年第3期15卷 92-106页

作者： Giles Blaney Martina Bottoni an.elo sassaroli Cristianne Fernandez Sergio Fantini Department of Biomedical Engineering Tufts University 4 Colby StMedfordMA 02155USA Department of Biomedical Engineering Politecnico di Torino 24 Corso Duca degli AbruzziTorinoTO 10129Italy

We investigated the relationship between chromophore concentrations in two-layered scattering media and the apparent chromophore concentrations measured with broadband optical spectroscopy in conjunction with commonly used homogeneous medium inverse *** used diffusion theory to generate optical data from a two-layered distribution of relevant tissue absorbers,namely,oxyhemoglobin,deoxyhemoglobin,water,and lipids,with a top-layer thickness in the range 1–15 *** generated data consisted of broadband continuous-wave(CW)diffuse reflectance in the wavelength range 650–1024 nm,and frequency-domain(FD)diffuse reflectance at 690 and 830 nm;two source-detector distances of 25 and 35mm were used to simulate a dual-slope *** data were inverted using diffusion theory for a semi-infinite homogeneous medium to generate reduced scattering coeffcients at 690 and 830nm(from FD data)and effective absorption spectra in the range 650–1024nm(from CW data).The absorption spectra were then converted into effective total concentration and oxygen saturation of hemoglobin,as well as water and lipid *** absolute values,it was found that the effective hemoglobin parameters are typically representative of the bottom layer,whereas water and lipid represent some average of the respective concentrations in the two *** concentration changes,lipid showed a significant cross-talk with other absorber concentrations,thus indicating that lipid dynamics obtained in these conditions may not be *** systematic simulations of broadband spectroscopy of two-layered media provide guidance on how to interpret effective optical properties measured with similar instrumental setups under the assumption of medium homogeneity.

关键词： Broadband spectroscopy two-layer medium heterogeneous forward model homo-geneous inverse model partial-volume effect

The meaning of “coherent” and its quantication in coherent hemodynamics spectroscopy

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Journal of Innovative Optical Health Sciences 2018年第6期 55-77页

作者： an.elo sassaroli Kristen Tgavalekos Sergio Fantini Department of Biomedical Engineering Tufts University MedfordMA 02155USA

We have recently introduced a new technique,coherent hemodynamics spectroscopy(CHS),which aims at characterizing a specic kind of tissue hemodynamics that feature a high level of covariation with a given physiological *** this study,we carry out a detailed analysis of the signicance of coherence and phase synchronization between oscillations of arterial blood pressure(ABP)and total hemoglobin concentration([Hbt]),measured with near-infrared spectroscopy(NIRS)during a typical protocol for CHS,based on a cyclic thigh cuffocclusion and *** though CHS is based on a linear time invariant model between ABP(input)and NIRS measurands(outputs),for practical reasons in a typical CHS protocol,we inducenite“groups”of ABP oscillations,in which each group is characterized by a different *** this reason,ABP(input)and NIRS measurands(output)are not stationary processes,and we have used wavelet coherence and phase synchronization index(PSI),as a metric of coherence and phase synchronization,*** was calculated by using both the wavelet cross spectrum and the Hilbert *** have also used linear coherence(which requires stationary process)for comparison with wavelet *** of surrogate data is used tond critical values for the signicance of covariation between ABP and[Hbt].Because we have found similar critical values for wavelet coherence and PSI by usingve of the most used methods of surrogate data,we propose to use the data-independent Gaussian random numbers(GRNs),for *** using wavelet coherence and wavelet cross spectrum,and GRNs as surrogate data,we have found the same results for the signicance of coherence and phase synchronization between ABP and[Hbt]:on a total set of 20 periods of cuffoscillations,we have found 17 coherent oscillations and 17 phase synchronous *** synchronization assessed with Hilbert transform yielded similar results with 14 phase synchronous *** coherence and wave

关键词： Wavelet coherence phase synchronization near-infrared spectroscopy surrogate data