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Latest Developments in fMRI

Latest Developments in fMRI. Peter A. Bandettini, Ph.D Unit on Functional Imaging Methods & 3T Neuroimaging Core Facility Laboratory of Brain and Cognition National Institute of Mental Health. Technology. Methodology. Interpretation. Applications. Technology. Methodology. Engineers.

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Latest Developments in fMRI

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  1. Latest Developments in fMRI Peter A. Bandettini, Ph.D Unit on Functional Imaging Methods & 3T Neuroimaging Core Facility Laboratory of Brain and Cognition National Institute of Mental Health

  2. Technology Methodology Interpretation Applications

  3. Technology Methodology Engineers Statisticians Physicists Mathematicians Neuroscientists Clinicians Physiologists Interpretation Applications

  4. Diff. tensor Technology Mg+ 7T >8 channels 1.5T,3T, 4T EPI on Clin. Syst. Venography Real time fMRI EPI SENSE Nav. pulses Local Human Head Gradient Coils Quant. ASL Z-shim Baseline Susceptibility MRI Dynamic IV volume Spiral EPI ASL Current Imaging? BOLD Simultaneous ASL and BOLD Multi-shot fMRI Correlation Analysis CO2 Calibration Methodology Motion Correction Parametric Design Multi-Modal Mapping Surface Mapping Baseline Volume Free-behavior Designs ICA Phase Mapping Mental Chronometry Multi-variate Mapping Linear Regression IVIM Deconvolution Fuzzy Clustering Event-related BOLD models PET correlation Interpretation IV vs EV ASL vs. BOLD Bo dep. Pre-undershoot PSF of BOLD TE dep Resolution Dep. Extended Stim. Blood T2 Post-undershoot Metab. Correlation Linearity SE vs. GE CO2 effect Optical Im. Correlation Hemoglobin Fluctuations NIRS Correlation Balloon Model Electrophys. correlation Inflow Veins Complex motor Applications Memory Imagery Emotion Language Children Drug effects Motor learning Tumor vasc. BOLD -V1, M1, A1 Presurgical Ocular Dominance Attention Volume - Stroke Clinical Populations V1, V2..mapping Priming/Learning D Volume-V1 Performance prediction Plasticity Face recognition 36 82 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02

  5. Alternating Left and Right Finger Tapping ~1992

  6. The use of fMRI for the Investigation of Brain Function and Physiology • Where? • When? • How much? • How to do it well? • Is there more?

  7. A Primary Challenge for Observing Brain Activation with fMRI: ...to make progressively more precise inferences without making too many assumptions about non-neuronal physiologic factors.

  8. Neuronal Activation Measured Signal Hemodynamics Noise ? ? ?

  9. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  10. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  11. Single Shot EPI T2* decay EPI Readout Window ≈ 20 to 40 ms

  12. P. A. Bandettini, Functional MRI temporal resolution in "Functional MRI" (C. Moonen, and P. Bandettini., Eds.), p. 205-220, Springer - Verlag,. 1999.

  13. + 2 sec Latency - 2 sec Magnitude P. A. Bandettini, The temporal resolution of Functional MRI in "Functional MRI" (C. Moonen, and P. Bandettini., Eds.), p. 205-220, Springer - Verlag,. 1999.

  14. Venogram (3 Tesla)

  15. Hemi-Field Experiment 9.0 seconds 15 seconds 500 msec 500 msec 20 30 10 Time (seconds) Right Hemisphere Left Hemisphere

  16. 0 10 20 30 500 ms 500 ms RightHemifield Left Hemifield + 2.5 s - = 0 s - 2.5 s

  17. Hemodynamic Response Modulation Bottleneck In Processing (upstream) Delayed Processing (downstream)

  18. 11026–11031 PNAS September 26, 2000vol. 97 no. 20

  19. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  20. Single Shot Imaging T2* decay EPI Readout Window ≈ 20 to 40 ms

  21. T2* decay EPI Window Partial k-space imaging

  22. Partial k-space imaging Jesmanowicz, P. A. Bandettini, J. S. Hyde, (1998) “Single shot half k-space high resolution EPI for fMRI at 3T.” Magn. Reson. Med. 40, 754-762.

  23. T2* decay EPI Window 1 Multishot Imaging T2* decay EPI Window 2

  24. Multi Shot EPI Excitations 1 2 4 8 Matrix Size 64 x 64 128 x 128 256 x 128 256 x 256

  25. Perfusion Rest Activation BOLD P. A. Bandettini, E. C. Wong, Magnetic resonance imaging of human brain function: principles, practicalities, and possibilities, in "Neurosurgery Clinics of North America: Functional Imaging" (M. Haglund, Ed.), p.345-371, W. B. Saunders Co., 1997.

  26. Anatomy BOLD Perfusion P. A. Bandettini, E. C. Wong, Magnetic resonance imaging of human brain function: principles, practicalities, and possibilities, in "Neurosurgery Clinics of North America: Functional Imaging" (M. Haglund, Ed.), p.345-371, W. B. Saunders Co., 1997.

  27. Arterial inflow (BOLD TR < 500 ms) Venous inflow (for ASL, w/ no VN) Pulse Sequence Sensitivity Spatial Heterogeneity

  28. Menon, et al ODC Maps using fMRI 1 cm calcarine • Identical in size, orientation, and appearance to those obtained by optical imaging1 and histology3,4. 1Malonek D, Grinvald A. Science 272, 551-4 (1996). 3Horton JC, Hocking DR. J Neurosci 16, 7228-39 (1996). 4Horton JC, et al. Arch Ophthalmol 108, 1025-31 (1990).

  29. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  30. CC Histogram Continuously Growing Activation Area Inflection Point Ziad Saad, et al

  31. 1000 800 600 400 200 0 200 400 600 800 1000 Temporal S/N vs. Image S/N PHANTOMS SUBJECTS 1400 1200 1000 800 600 400 200 Temporal S/N Temporal S/N 0 200 400 600 800 1000 1200 1400 Image S/N Image S/N N. Petridou

  32. Signal / Thermal Noise Signal / Physiologic Noise Signal to Noise Ratio Optimal for fMRI Resolution, Speed, Surface Coils, Field Strength, etc..

  33. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  34. D Neuronal Activity Number of Neurons Local Field Potential Spiking Coherence Spiking Rate D Metabolism Aerobic Metabolism Anaerobic Metabolism - Blood Volume Deoxygenated Blood D Hemodynamics - Flow Velocity Oxygenated Blood + Perfusion D BOLD Contrast D Deoxy-Hb MRI Pulse Sequence D Perfusion Contrast D Inflow Contrast

  35. Motor Cortex Auditory Cortex S. M. Rao et al, (1996) “Relationship between finger movement rate and functional magnetic resonance signal change in human primary motor cortex.” J. Cereb. Blood Flow and Met. 16, 1250-1254. J. R. Binder, et al, (1994). “Effects of stimulus rate on signal response during functional magnetic resonance imaging of auditory cortex.” Cogn. Brain Res. 2, 31-38

  36. Logothetis et al. (2001) “Neurophysiological investigation of the basis of the fMRI signal” Nature, 412, 150-157 S. M. Rao et al, (1996) “Relationship between finger movement rate and functional magnetic resonance signal change in human primary motor cortex.” J. Cereb. Blood Flow and Met. 16, 1250-1254.

  37. time (s) Different stimulus “ON” periods measured linear BOLD Response Signal Stimulus timing 0.25 s 0.5 s 1 s 2 s 20 s Brief stimuli produce larger responses than expected

  38. 8 f (SD) 6 4 2 0 10 20 30 40 0 1 2 3 4 5 0 10 20 30 40 Stimulus Duration -2 8 f (SD) 6 60 4 40 2 20 0 1 2 3 4 5 0 2 0 2 4 6 8 Stimulus Duration -2 nonlinearity Results – visual task

  39. Results – visual task Nonlinearity Magnitude Latency

  40. Sources of this Nonlinearity • Neuronal • Hemodynamic • Oxygen extraction • Blood volume dynamics Oxygen Extraction Flow In Flow Out D Volume

  41. BOLD Correlation with Neuronal Activity Logothetis et al. (2001) “Neurophysiological investigation of the basis of the fMRI signal” Nature, 412, 150-157. P. A. Bandettini and L. G. Ungerleider, (2001) “From neuron to BOLD: new connections.” Nature Neuroscience, 4: 864-866.

  42. 20 3 15 2 10 BOLD (% increase) CBF (% increase) 5 1 0 0 -5 -10 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 Time (seconds) Time (seconds) CBF BOLD Simultaneous Perfusion and BOLD imaging during graded visual activation and hypercapnia N=12

  43. Computed CMRO2 Changes 40 30 20 10 0 % % -10 -20 -30 -40 Subject 2 Subject 1

  44. CBF OEF CMRO2

  45. Latest Developments… • Temporal Resolution • Spatial Resolution • Sensitivity and Noise • Information Content • Implementation

  46. Neuronal Activation Input Strategies • Block Design • 2. Parametric Design • 3. Frequency Encoding • 4. Phase Encoding • 5. Event Related • 6. Orthogonal Design • 7. Free Behavior Design

  47. First Event-related fMRI Results Blamire, A. M., et al. (1992). “Dynamic mapping of the human visual cortex by high-speed magnetic resonance imaging.” Proc. Natl. Acad. Sci. USA 89: 11069-11073.

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