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Project 4 - aims. GOAL Advance the development of DOI to improve image accuracy, repeatability, CNR, and depth sensitivity. AIM 1 – Instrumentation Continuous-wave and Time-Domain AIM 2 – Signal Processing Algorithms to filter signal clutter AIM 3 – Experiments to quantify improvements - PowerPoint PPT Presentation
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Project 4 - aimsGOALAdvance the development of DOI to improve image accuracy, repeatability, CNR, and depth sensitivity.
AIM 1 InstrumentationContinuous-wave and Time-Domain
AIM 2 Signal Processing Algorithms to filter signal clutter
AIM 3 Experiments to quantify improvements
Parallel Efforts of Hardware development (year 1) and Signal Processing of physiological fluctuations (year 2)To come together in future years
instrument development - CWTechen Inc
Framework for Multimodal AnalysisNeurovascular physiology is modeled with a cascade of functionsLead fields model the biophysics of each imaging modalityThe functions evolve with neuroscience while the framework remains the same Key: u=observable inputs x=state variables w=process noise =model parameters z=physiological signals F=lead fields v=measurement noise y=measurements
Why fuse DOT and fMRI?Combine best of both SPECTRAL, TEMPORAL, and SPATIAL better quantification of physiology !
Improve statistical power in spatial map by improving rejection / filtering of systemic signals !
Caution: a bit of math
Caution: a bit of mathSimulations confirm improvement in quantitative accuracy in HbR !
Experimental Results
FusionImproved Quantitative HbRReconstructed [HbR]Subject ACortical ConstraintDOTBOLD
Windkessel Model Flow/Volume changes are driven by changes in arteriole resistanceAnalogous to a circuit model with oxygen diffusion
Windkessel Analysis of Human DataHbO2HbTHbRTime (sec)Molar0246810-202468x 10-6Percent ChangeASL - CBFTime (sec)BOLD x 100246810-0.0500.050.10.150.20.250.3Baseline CMRO25.2 ml O2 / 100 g / min
Framework for Multimodal AnalysisNeurovascular physiology is modeled with a cascade of functionsLead fields model the biophysics of each imaging modalityThe functions evolve with neuroscience while the framework remains the same Key: u=observable inputs x=state variables w=process noise =model parameters z=physiological signals F=lead fields v=measurement noise y=measurements
signal processing to filter physiological clutter from brain activation signalsour raw optical data show ~1Hz cardiac pulsation, ~0.1-0.3 Hz blood pressure and respiration fluctuations Need to filter this interference Interference is physiology of interest (autoregulation)
Baseline physiology with simulated functional response added
Recovering the hemodynamic response function
Cerebral autoregulation response to a step increase in blood pressure
Combine DOI and fMRIto get more complete understandingof physiology
Coupling of the hemoglobin response with the N1 somatosensory evoked potential component and uncoupling with the other SEP components
123401Hz3Hz5Hz7Hz1Hz3Hz5Hz7Hz51015Time (s)Time (s)0hemoglobin conc. changes (au)SEP (au)frequency
MTHbO2 changes (au)12345678sdurationamplitudefrequency0.5.7511.2512345678HzTime (s)HbO2 changes (au)Time (s)SP1N1P2HbO2
STSP1SN1SP2(a)(b)(c)Normalized SHbO2Normalized SSEPSHbO2
measuring brain development in healthy infants
frontal cortexCBV (ml/100g)age (wks)StO2 (%)HbT (mM)2040608012344050607001020304050P 0.02P 0.004P 0.001P 0.001P 0.005P 0.1P 0.00008P 0.000000001P 0. 8changes with age
CBV (ml/100g)StO2 (%)HbT (mM)2040608012344050607001020304050P 0.02P 0.004P 0.1effect of the transition from fetal to adult hemoglobinage (wks)
cerebral metabolic rate of oxygen (CMRO2)StO2 = aSaO2 + bSvO2 with a+b=1 (we assume b constant with age and SaO2=1)
frontal cortexCBV (ml/100g)age (wks)StO2 (%)HbT (mM)2040608012344050607001020304050P 0.02P 0.004P 0.1P 0.001P 0.001P 0.005changes in CMRO2
frontal cortexDCMRO2=0.91-6 wksDCMRO2=1.3, b=2DCMRO2=1.7, b=312-52 wkschanges in CMRO2CMRO2 constant & initial drop of StO2 due to the hematocrit dropelectrophysiological studies first two months synaptic activity very lowNMR studies in newborn very low rates of CMRO2 energy requirements possibly met by nonoxidative metabolism 40% increase in the sensorimotor cortex
The TeamOptical Imaging GroupAnna CustoSol DiamondMaria Angela FranceschiniTed HuppertDanny JosephIlkka NissilaJuliette Selb
MGHGiorgio BonmassarBruce FischlEllen GrantMatti HamalainenBruce RosenLarry Wald
USCDAnders Dale
Northeastern UniversityDana BrooksEric Miller
Texas A&MHeather BortfeldTeresa Wilcox
Univ College LondonSimon Arridge
Univ of Kuopio, FinlandJari KaipioVille Kolehmainen
A little bit of history of the field. I worked in Nirs for ~10 years. First in Illinois @ UIUC on the group of Enrico Gratton, ~1993-94 we developed the first prototype and ISS marketed the following generations of F-D oximeters.At MGH David Boas developed various CW instruments which are now assembled by Techen....
If anyone asks, the BPV input and HbT outputs were high pass filtered with a 0.05 Hz cutoff. The sampling rate is 1 Hz. I fit a 5th order ARX model to the data with one of Matlab's system id tools. The step response amplitudes were normalized so that the final value of HbT in the scalp was unity.HbT changes region to region and more marked changes with ageStO2 shows much less regional and temporal changes despite marked changes in HbTThis suggests that capillary development is keeping pace with demand such that StO2 remains relatively stableHbT changes region to region and more marked changes with ageStO2 shows much less regional and temporal changes despite marked changes in HbTThis suggests that capillary development is keeping pace with demand such that StO2 remains relatively stableHbT changes region to region and more marked changes with ageStO2 shows much less regional and temporal changes despite marked changes in HbTThis suggests that capillary development is keeping pace with demand such that StO2 remains relatively stableHbT changes region to region and more marked changes with ageStO2 shows much less regional and temporal changes despite marked changes in HbTThis suggests that capillary development is keeping pace with demand such that StO2 remains relatively stable