Podcast
Questions and Answers
What does the BOLD technique in fMRI primarily measure?
What does the BOLD technique in fMRI primarily measure?
Which cellular structures are involved in providing oxygen to the brain's energy supply?
Which cellular structures are involved in providing oxygen to the brain's energy supply?
What distinguishes the simplest fMRI task design mentioned?
What distinguishes the simplest fMRI task design mentioned?
What is referred to by ‘functional connectivity’ in the context of fMRI?
What is referred to by ‘functional connectivity’ in the context of fMRI?
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The increase in cerebral blood flow (CBF) during visual stimulation is primarily seen in which brain area?
The increase in cerebral blood flow (CBF) during visual stimulation is primarily seen in which brain area?
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Which of the following best describes the T2*-sensitive sequences used in fMRI?
Which of the following best describes the T2*-sensitive sequences used in fMRI?
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In the historical context, what was Mosso's apparatus used for?
In the historical context, what was Mosso's apparatus used for?
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What percentage of the brain's energy supply is accounted for by arteries, veins, and capillaries?
What percentage of the brain's energy supply is accounted for by arteries, veins, and capillaries?
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What is the Larmor frequency in relation to a spin system?
What is the Larmor frequency in relation to a spin system?
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How does a wider range of coverage in k-space impact image resolution?
How does a wider range of coverage in k-space impact image resolution?
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What information does the center of k-space provide?
What information does the center of k-space provide?
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In the equation ω = γB, what does each variable represent?
In the equation ω = γB, what does each variable represent?
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What does the periphery of k-space provide in terms of image information?
What does the periphery of k-space provide in terms of image information?
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What do basic sampling units differ between k-space and image space?
What do basic sampling units differ between k-space and image space?
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What does the Fourier Transform accomplish in the context of MRI?
What does the Fourier Transform accomplish in the context of MRI?
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What is the role of the head coil in MRI focusing?
What is the role of the head coil in MRI focusing?
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What is primarily affected in Parkinson's disease?
What is primarily affected in Parkinson's disease?
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In fMRI studies of Alzheimer's disease (AD), what is suggested by hyperactivity during memory trials?
In fMRI studies of Alzheimer's disease (AD), what is suggested by hyperactivity during memory trials?
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What neuroimaging technique is sensitive to iron presence in the brain?
What neuroimaging technique is sensitive to iron presence in the brain?
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What may contribute to the loss of dopamine-producing neurons in Parkinson's disease?
What may contribute to the loss of dopamine-producing neurons in Parkinson's disease?
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What cognitive abilities were observed in at-risk patients during fMRI tasks in studies related to Alzheimer's disease?
What cognitive abilities were observed in at-risk patients during fMRI tasks in studies related to Alzheimer's disease?
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How do iron-rich structures appear on T2-weighted MRI images?
How do iron-rich structures appear on T2-weighted MRI images?
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What effect does repeated exposure to jet lag have on salivary cortisol levels in cabin crew?
What effect does repeated exposure to jet lag have on salivary cortisol levels in cabin crew?
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What hypothesis is suggested regarding high cortisol elevations and their effects?
What hypothesis is suggested regarding high cortisol elevations and their effects?
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What characterized the short-recovery group of flight attendants?
What characterized the short-recovery group of flight attendants?
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How many subjects were tested in each flight attendant group?
How many subjects were tested in each flight attendant group?
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What is the primary measurement method mentioned for assessing brain activity?
What is the primary measurement method mentioned for assessing brain activity?
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What aspect of brain structure was examined in relation to jet lag?
What aspect of brain structure was examined in relation to jet lag?
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Which group had recovery intervals of more than 14 days?
Which group had recovery intervals of more than 14 days?
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Which of the following best describes brainwaves?
Which of the following best describes brainwaves?
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What was a key difference between the two flight attendant groups studied?
What was a key difference between the two flight attendant groups studied?
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Which term refers to the measurement of electrical patterns on the scalp?
Which term refers to the measurement of electrical patterns on the scalp?
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What are the primary functions of RF coils in an MRI system?
What are the primary functions of RF coils in an MRI system?
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What ensures the homogeneity of the static magnetic field in MRI?
What ensures the homogeneity of the static magnetic field in MRI?
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Which of the following statements about T1 and T2 is correct?
Which of the following statements about T1 and T2 is correct?
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Which component begins to recover after RF is turned off in MRI?
Which component begins to recover after RF is turned off in MRI?
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What type of MRI images are produced by using short acquisition times?
What type of MRI images are produced by using short acquisition times?
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Time to Echo (TE) refers to which aspect of MRI imaging?
Time to Echo (TE) refers to which aspect of MRI imaging?
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Which property does T2* depend on in addition to tissue characteristics?
Which property does T2* depend on in addition to tissue characteristics?
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What is the consequence of spins getting out of phase with each other in MRI?
What is the consequence of spins getting out of phase with each other in MRI?
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What is a primary cognitive domain affected by cognitive impairment?
What is a primary cognitive domain affected by cognitive impairment?
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Which of the following is NOT a factor contributing to cognitive impairment?
Which of the following is NOT a factor contributing to cognitive impairment?
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What cognitive function is primarily associated with changes in the hippocampus?
What cognitive function is primarily associated with changes in the hippocampus?
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Which symptom is characteristic of Alzheimer's disease?
Which symptom is characteristic of Alzheimer's disease?
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Mild Cognitive Impairment (MCI) is best described as:
Mild Cognitive Impairment (MCI) is best described as:
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Which of the following is a potential underlying cause of Mild Cognitive Impairment?
Which of the following is a potential underlying cause of Mild Cognitive Impairment?
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Neurofibrillary tangles are associated with which condition?
Neurofibrillary tangles are associated with which condition?
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What effect does impaired neurotransmission have on cognitive function?
What effect does impaired neurotransmission have on cognitive function?
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Study Notes
BM402: Engineering in Medicine
- Course name: Engineering in Medicine
- Date: October 17, 2024
- Location: M 2170 - South Campus
MRI
- MRI type: Functional MRI
- Applications: MRI and fMRI
- Other imaging type: EEG
- Applications: EEG
- Other imaging type: Multimodal Imaging
Brain Imaging
- Imaging techniques: X-Ray, CT, PET Scan, MRI, MRA
- Specific MRI Anatomical Scan: Axial view, Sagittal view, Healthy volunteer, Siemens 3T MR Scanner
fMRI: Functional Scan
- Functional network types: Primary visual, Lateral visual, Medial visual, Sensory-motor, Right lateral, Left lateral, Precuneus, Ventral stream, Medial temporal, Salience, Task positive, Auditory, Default mode
- Z-score data: Veer et al. 2010
Magnetic Resonance Imaging: MRI
- MRI scanner: Giant magnet
- Magnet strength: Measured in Tesla (T)
- Earth's magnetic field strength: ~0.00006 T
- 3T MRI scanner strength: ~50,000 times stronger than Earth's field
- Clinical MRI scanners: 1.5T or 3T
- Research MRI scanners: 7T, 10.4T and 11.7T
- Helium for cooling coils: ~35,000 liters required for 11.7T scanner
MRI: How it Works
- Hydrogen protons in H2O molecules
- Protons spin in a magnetic field
- Precessional frequency: Rate of proton spin in a magnetic field
- RF: Radio frequency pulse, tips protons away from B0 field
- On Resonance: Protons have same frequency
- Fourier Transform: Changes electrical current in a coil to create an image, relates the Larmor frequency.
MRI: Focusing Our Imaging
- Magnetic field strength
- White Matter
- CSF
- Grey Matter
- Coil
- Current
MRI: Image Formation (detailed)
- Main Magnet
- Coils (x, y, z gradient coils, rf receiver coil, rf transmitter (body) coil)
- Patient table
- RF pulse (90 degree rf pulse)
- Gradient pulse (applied along z axis)
- Fourier Transform (FT)
Fourier Transform
- 2D Inverse Fast Fourier Transform (2D IFFT) converts from k-space to image space
Converting from k-space to image space
- Image space: Basic sampling unit is distance
- K-space: Basic sampling unit is spatial frequency (1/distance)
- Wider k-space coverage: Higher spatial resolution in image space (smaller voxels)
- Center of k-space (B): Low-spatial frequency info, retains most signal but not fine details
- Periphery of k-space (C): High spatial-frequency info, finer details, contributes relatively little signal
First MR Image
- 2003 Nobel Prize not for medical applications of MRI but development of imaging techniques
- Early large-bore MRI scanner labeled "Indomitable" by Damadian et al. (1977)
- The first image of a human body, subject Larry Minkoff
MRI Basics
- Rabi used strong magnetic field to measure spin properties of nuclei
- MRI scanners use strong magnetic field to induce changes in proton spin
- Bloch detected nuclear induction
- Lauterbur manipulated magnetic field strength creating image
- MRI studies use magnetic gradients for image creation
MRI Hardware
- Static magnetic field
- Gradient coils
- RF coils (Tx-Coil and Rx-Coil): excitation and signal reception
- Shimming coils
MRI Image Contrast (T1, T2, T2*)
- T1 and T2: Inherent to tissues (fixed for specific tissues at given magnetic field strength)
- T2*: Depends on inhomogeneities in main magnetic field
- T1-weighted images: Short acquisition times, white matter appears light
- T2-weighted images: Longer times, gray matter appears bright
- T2, T2*, Free Induction Decay (FID)
T2* and Functional MRI (fMRI)
- BOLD (Blood Oxygen Level Dependent) technique: Image contrast based on deoxy- and oxy-hemoglobin levels in local brain
- Deoxyhemoglobin: Paramagnetic, shortens T2 and T2* and decreases signal
- Neural activity: Affects blood oxygen levels
- Blood oxygenation changes: Changes in MR signal
Functional MRI – Task Design
- Simplest task: eyes open and eyes closed
- BOLD signal intensity differences in primary visual cortex observed.
Functional Connectivity
- Correlations in spontaneous blood oxygen level dependent (BOLD) fluctuations
- Examining inter-regional correlations in neuronal variability
Jetlag
- Chronic 'jet lag' causes temporal lobe atrophy and spatial cognitive deficits
- Repeated exposure to jet lag leads to reduced temporal lobe volume and deficits in spatial learning and memory
- High cortisol associated with cognitive deficits
- Cortisol levels higher in cabin crew with repeated jet lag compared to short distance flights
EEG Basics
- Electro-encephalo-gram (EEG): Measurement of electrical patterns at the surface of the scalp, reflecting cortical activity
- Electrical activity: Brainwaves (Delta, Theta, Alpha, Beta, Gamma)
EEG History
- Hans Berger: Initial observations
- Technology advances over time (EEG recording equipment, computer-aided signal processing)
EEG - Brain Rhythms
- Different brainwave frequencies (Delta, Theta, Alpha, Beta, Gamma)
- Associated with different brain functions and mental states
Electrocorticography
- ECOG, IEEG
- Intracortical microelectrodes: deep brain recording
- Grid and stick electrodes: recording brain activity
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Description
Dive into the essential concepts of Engineering in Medicine with a focus on Magnetic Resonance Imaging (MRI) and its applications in brain imaging. This quiz explores various types of MRI, functionalities of fMRI, and comparisons with other imaging techniques like EEG and PET scans. Prepare to test your knowledge on the anatomical and functional aspects of MRI in a clinical and research context.
