Introduction and Imaging

Question 1

Apical

Answer 1

Pertaining to the tip or apex

Question 2

Basal

Answer 2

Pertaining to the bottom or base

Question 3

Rostral

Answer 3

Situated towards the nose or brow

Question 4

Basilar

Answer 4

Pertaining to the skull base

Question 5

Qualities of CT scan-
How does it work?
2D or 3D
Contrasting agent

Answer 5

X-ray based. Computer detects signal strength exiting opposing side of tissue.

Creates 2D image
Iodine used as contrasting agent in brain and neck
180 degree ar

Question 6

CT advantages and disadvantages

Answer 6

Advantage
-Cheap relative to MRI

Disadvantages

• Joints and some tissues don’t age well
• Can only 1-2 times a year max

Question 7

What colors are these structures in a CT scan and why?

Bone, Acute blood 
Enhanced tumor 
Subacute blood                 
Muscle
Grey matter 
White matter
Cerebrospinal fluid                          
Air, Fat

Answer 7

Dense structures appear white.
Medium density structures are grey
Low density structures are black

Sends signal. If it can go straight through = not dense. Black.
Sends signal. If it can’t go straight through = very dense. White.

Bone, Acute blood - very white 
Enhanced tumor - very white 
Subacute blood - light grey
Muscle - light grey 
Grey matter - light grey 
White matter -medium grey 
Cerebrospinal fluid - medium grey to black 
Air, Fat - Very black

Question 8

Which is more dense? White or grey matter?

Answer 8

Grey matter is more dense. Will appear lighter than white matter in CT scan

Question 9

What does MRI stand for

Answer 9

Magnetic resonance imaging

Question 10

How does MRI create a 2-dimensional image

Answer 10

Based on how Hydrogen atoms, or protons, spin.
The machine has a north and south pole used to create a magnetic field. The field causes Hydrogen atoms to spin in the same/specific direction instead of allowing them to spin freely. Once the magnetic field shuts off, the machine picks up how long it takes for the spin to go back to normal. The Hydrogen atoms give off energy as their magnetic field return to baseline.

Question 11

T1 weighted MRI vs T2 weighted MRI

Answer 11

T1: Created from cancelled atoms returning to baseline.
T2: Created from enhanced atoms returning to baseline. Once the machine turns off, the Hydrogen atoms will try to go back to normal. Over time, one of the adjacent H atoms will change orientation slightly.

Question 12

Is T1 weighted or T2 weighted MRI used more commonly?

Answer 12

T2 weighted. Especially for edema- produces a light brighter image.

Question 13

What colors are these structures in an MRI and why?

Bone 
Air 
Muscle
Grey matter
White matter 
Fat
Cerebrospinal fluid
Edema
Tumor 
Infarct
Ischemia

Answer 13

Bone- Very black in T1 and T2
Air- Very black in T1 and T2
Muscle- Dark grey in T1 and T2
White matter- Light grey in T1 and dark grey in T2
Grey matter- Dark grey in T1 and light grey in T2
Fat- White in T1 and grey in T2
Cerebrospinal fluid- Very black in T1 and very white in T2
Tumor- Variable
Infarct (necrosis) - Dark grey in T1 and light grey/white in T2
Ischemia(artery blockage or build up)- Dark grey in T1 and light grey/white in T2

Question 14

White mater is lighter than grey matter in ____ MRI

Grey matter is lighter than white matter in ____ MRI

Answer 14

T1

T2

Question 15

Where is white and grey matter located at in the brain

Answer 15

White- Center

Grey- Peripheral (more dense)

Question 16

What does MRA stand for

Answer 16

Magnetic resonance angiography

Question 17

How does MRA work

Answer 17

Looks at vasculature in the neck or brain and can determine if there is stenosis (spinal narrowing) or plaque.
This is not ordered often and a little more expensive.
An alternative method used is ultrasound.

Question 18

What is the basis of a fMRI

Answer 18

Functional MRI works by taking advantage of the higher magnetism of deoxyhemoglobin compared to oxyhemoglobin. Therefore, you can tell which areas of the brain require more or less oxygen meaning more or less metabolic activity. 2D.

Question 19

Compare fMRI and PET 
Price
Agents used 
Resolutions
Duration/patient requirements

Answer 19

fMRI:

• cheaper due to use of MRI
• No radioactive or contrasting agent
• High resolution
• Complete stillness or 45 minutes. Lous.

PET:

• More expensive bc it requires a special machine
• Radioactive agent injected
• Low resolution
• Subject can move freely and only lasts 5-10 minutes.

Question 20

When to order an x-ray

Answer 20

• Cheaper than a CT
• Fractured bones
• Tissue changes ex: tumor in lungs
• only need 2D image

Question 21

What does PET scan stand for

Answer 21

Positron emission tomography

Question 22

What is a PET scan

Answer 22

-A FANCY CT scan that is VERY expensive (5-10k)

Question 23

Which 2 scans have the ability to track metabolic activity

Answer 23

PET scan through use of glucose

fMRI through use of deoxy and oxyhemoglobin

Question 24

How does a PET scan work

Answer 24

When A mix of isotopes and glucose are injected into the body, metabolically active tissue will take up the glucose. Once the isotope begins to decay, the PET scan will pick up the released energy from the decay.

More metabolically active- more bright and vibrant colors.

Question 25

When to ordre a PET scan

Answer 25

• Seizures
• TBI
• Schizophrenia
• Tumor/cancer cells
• Movement disorders

All of these will display an abnormal level of metabolic activity in the brain. Although expensive, this test is quick and the patient is allowed to move around more freely than compared to an fMRI.