NROb60 - Final Exam Questions With 100% Verified Answers
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NROb60
NROb60 - Final Exam Questions With 100%
Verified Answers
Lecture 6 - The first phase of human brain-imaging involved X-ray based methods, such as----- -
answerpneumoencephalography
pneumoencephalography - how does this work generally , what are the cons of this method -
answer•Air is injecte...
NROb60 - Final Exam Questions With 100%
Verified Answers
Lecture 6 - The first phase of human brain-imaging involved X-ray based methods, such as----- -
answer✔pneumoencephalography
pneumoencephalography - how does this work generally , what are the cons of this method -
answer✔•Air is injected into subarachnoid space to improve X-ray contrast
•Makes the ventricles more translucent than surrounding tissue - specifically the lateral ventricles
- You can see the c shape of the lateral ventricles
- Was useful for visualizing ventricular anomalies causing hydrocephalus, but comes with risks
and discomfort.
Very invasive and unpelasent
But you cant see the brain completely
how does cerebral angiography generally work - answer✔, X-ray images reveal blood vessels if
a contrast agent is introduced into arterial circulation
•X-ray images taken in different planes to visualize full network
•Time-lapse images will spread through major arteries first
- helps Visualize different arteries
- Done in a timeline sequence so you can watch the contrast dye go into all the little branches
The approach allowed identification of arterio-venous malformations and other vascular
anomalies, such as arterial occlusions • Helped inform clinical assessments of strokes
however there are substantial risks with this
in slide 7 week 7 how do you which artery is being supplied - answer✔Internal carotid artery aca
and mca are being supplied - theres a lack of dye in the back of the brain and cerebellum so that's
how we know
Here visualzing arteries
computerized tomography (CT) - answer✔the X-ray source and
detector are moved around the individual's head
•Distinguishes gray and white matter, ventricles, and major anatomical structures
•Spatial resolution of a few millimeters
In CT, a narrow X-ray beam and very sensitive detectors are placed on opposite sides of the head
probe a small portion of tissue at a time with limited radiation exposure
- The X-ray tube and detectors rotate around the head, collecting radiodensity information from
every orientation around a narrow slice, that can be processed to produce a tomographic image.
The individual is then moved very slowly through the scanner to complete a set of serial sections
CT scans readily distinguish gray and white matter, differentiates the ventricles, and major
anatomical structures (spatial resolution of several millimeters) • The white matter tracts appear
as the darker color
what image does a ct scan create and what is this useful to study - answer✔Created a horizontal
image in this case - we can see that white matter is darker color, grey matter is lighter and the
ventricles are black here
Useful for detecting brain lesions like tumors, or hematoma you can visualize easily
CT is useful in detecting brain lesions where the damage has a different tissue density than the
normal brain tissue
•Metastatic brain tumors in breast cancer patient -->White spots throughout gray and white
matter
what are some cons of ct - answer✔risks associated with unnecessary radiation exposure and due
to its relatively low resolution of brain structures (compared to MRI
Development of -------- made it possible to construct detailed spatial images - answer✔Magnetic
Resonance Imaging (MRI)
explain the functions of mri and how it works - answer✔•Safe, noninvasive and versatile
Based on the physics of atomic motion
A magnetic coil is placed around the head to activate and record magnetic resonance signal
The nuclei of some atoms act as spinning magnets, randomly positioned normally in the body
• When placed in a strong magnitude field of the MRI machine, these atoms will line up with the
field and spin at a frequency that is dependent on the field strength
• A brief radiofrequency pulse knocks the atoms out of alignment with the field and when turned
off, the protons relax and emit a radio signal
• Almost all MRI scanners use detectors turned to the radio frequencies of spinning hydrogen
nuclei in water molecules, creating images based on the distribution of water in different tissues.
essentially Putting a person in a very strong magnet, atoms within soft tissue oreitn randomly in
normal cirucmtsances , but rn the mri is trelying on water
When placed under the strong magnetic force it forces the molecules to orient in the same
direction
Radio pulse makes it briefly disoroiet and then when it relaxes it orients it properly
Different tissue has diff water content so you can see different things
Now resolution is a mm
what resolution does mri have , what does the light or dark depend on - answer✔•Millimeter
resolution
•Light vs dark can reverse depending on pulse sequence used - soft tissue contrast can be
manipulated by adjusting the time at which the realigning hydrogen signal is measured
---- is a variant of MRI and identifies major axon pathways in the brain - answer✔Diffusion
Tensor Imaging (DTI)
what does dti do - answer✔•Detects similarities in the direction of water molecules within
specific regions of the magnetic field.
•Can't resolve individual axons, but can visualize the origin,
orientation, course, and termination of axonal bundles
how does the dti work - answer✔Used for when hydrogen atoms are moving and orienting to
magnetic and being disrupted by the energy pulse
Energy relates to types of tissue there is - when there are major axonal tracts in the brain they
share more similairites than tissues in the brain - can represent major fiber tracts - looking at
tracts going in the same direction
Identifies major axon pathways in the brain by detecting similarities in the direction of water
molecules within specific regions of the magnetic field, to visualize axonal connections between
regions.
• This information is then assembled into an image that indicates the degree of alignment of
water molecules in the tissue.
• Maximally aligned molecules (shown in different colors, depending upon shared directions)
define regions where major axon tracts are found in the cortical white matter and other brain
regions.
• Doesn't have the resolution to portray individual axons, but the origin, orientation, course, and
termination of axonal bundles can be effectively visualized
How do we map the major input and output connections to a brain region? - answer✔- using tract
tracing
Multiple different inputs come into a single brain region, and neurons from one region can
project to many others
Looking more at tract tracing and cell identity
Don't worry about the acronyms and things
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