(E2) Intro to cross sectional anatomy

advantages of cross sectional anatomy

• eliminates overlapping structures

• helps to differentiate between adjacent structures

• offers view of anatomy in a variety of planes

Sagittal plane or median =

left to right

axial plane or transverse =

inferior to superior

coronal plane or frontal=

posterior/anterior

what plane is 1?

sagittal

what plane is 2?

coronal

what plane is 3?

axial

thickness of slice is dependent on ____

technical settings

thinner slices = ____ detail

more

slices are determined by _____ and procedure protocols

institutional

slices are adjusted by

technologist/protocols

slices are annotated on scout images to provide ______ (scanogram)

regional location

____ patterns may change location of anatomy

breathing

specific arrangement of structures varies from _______

one person to the next

determining location of the slice helps to identify

anatomy

what is computed tomography

generates a 3D image of the body from a large series of 2D x-ray images taken around a single axis rotation

when was CT developed and publicized

in the 1970s

when was the first patients brain scan and how long was it

• 1971- London Atkinsons Morley Hospital

• 2.5 hours

hounsfield unit for bone is

• 1,000 HU (bright white)

hounsfield unit for water is

0 HU (gray)

hounsfield unit for air is

-1,000 HU (black)

hounsfield units represent the ____ of each tissue

densities

an ____ and ____ image is obtained ot designate where the slices will be imaging

AP and Lateral

slice thickness may very from _____ to _______

millimeters to centimeters

scans are taken on one plane and reconstructed to create the ____ and ____ planes

sagittal and coronal

Contrast use in CT:

• Iodine based and barium-sulfate type contrast can be used in CT

• this is used to highlight different structures of the body to evaluate pathologies and disease

advantages of CT

• visualization of anatomy without superimposition of structues

  • axial imaging

• ability to differentiate small differences in density of anatomic structures and abnormalities

CT: indications

• diagnose muscle and bone disorders

• detect internal injuries and internal bleeding

• pinpoint the location of a tumor, infection, clot

• guide procedures such as surgery, biopsy, Rad Therapy

• detect and monitor diseases and conditions

CT: contraindications

• higher doses

• contrast allergies, extravasation

• claustrophobia

Magnetic resonance is what

utilizes a powerful magnet field to align the magnetization of some atoms in the body

• magnetic properties of hydrogen atoms

MR was discovered in

1973

how does MRI work?

• a “coil” is placed around the area of interest to obtain the info of that area. the magnet aligns the single protons in the hydrogen nuclei within the field

• radio waves enter the patient from another angle, the radio waves cause the nuclei to flip positions and either align with the magnet or against it

• at termination of radio signals, nuclei return to original position by spinning like a top back into their varied position

• energy that is released from the relaxation is used to generate images

MRI T1 weighted images

• fat appears bright

• water appears dark'

• best for anatomy

MRI T2 weighted images

• water appears bright (white)

• fat appears dark

• best for pathology

Contrast use in MRI:

gadolinium is contrast used in many MRI scans to improve the clarity of the images and to improve the diagnostic accuracy of the MRI scan

Gandolinium is a safer contrast due to

less adverse reactions and eliminated through kidneys easier

advantages of MRI

• no exposure to ionizing radiation

• superior contrast resolution

• superior tissue characterization

• multi-planar capabilities

• possibly safer intravenous contrast agents

• visualization of angiography without using contrast

MRI: indications

a noninvasive way to examine organs, tissue and the skeletal system by producing high-resolution images that help diagnose a variety of problems

MRI: contraindications

• possible contrast allergy, extravasation

• metal

• take longer

• claustrophobia

• patient size (larger)

human body = ___% hydrogen

80

is this a T1 or T2 image?

T2

is this a T1 or T2 image?

T1

How does MRI and diagnostic work togther?

• x-ray can screen for metal before going to MRI

  • metal, pacemaker, abdomen

• fluoro and arthrograms

how does CT and diagnostic work together?

• better detail on fractures

• myelograms and arthrograms

• kidney stones

• abdomen x-ray looking for prior contrast before CT