Ultrasound, Computed Tomography, Magnetic Resonance Imaging

What kind of waves are in an ultrasound?

sound waves

How does an ultrasound work?

crystals in transducer convert sound waves to electric current, computer in ultrasound machine converts electric current to image

What kind of waves are in an ultrasound?

sound waves

How does an ultrasound work?

crystals in transducer convert sound waves to electric current, computer in ultrasound machine converts electric current to image

What is the fate of the sound wave?

goes through tissue or bounces back

What color is fluid in an ultrasound?

black

What color is soft tissue in an ultrasound?

gray

What color is fibrous tissue such as the diaphragm in an ultrasound?

white

What color are solid structures such as bone in an ultrasound?

white on top and then black underneath

How many waves are coming back in an ultrasound if you seen black?

none

How many waves are coming back in an ultrasound if you see white?

all

How many waves are coming back in an ultrasound if you see gray?

some

What substance content must you think about during an ultrasound?

water

What substance do ultrasounds hate and why?

air; all waves bounce back

How would you describe it if an U/S structure is darker than another one?

hypoechoic

How would you describe it if an U/S structure is brighter than another one?

hyperechoic

How would you describe it if an U/S structure is the same color as another structure?

isoechoic

How would you describe it if an U/S structure is black?

anechoic

What is an acoustic shadow?

ultrasound artifact where you cannot see below a structure that reflects back all the waves (bone)

What is an acoustic enhancement?

brightness deep to anechoic structure

What is a reverberation artifact?

sound waves reflecting multiple times between 2 strong reflectors (most common in lung)

What is a mirror image artifact?

duplication of image of the opposite of a strong reflector; most common from thorax/abdomen interface

What is a slice thickness artifact?

from imaging a 3D structure with anechoic fluid; most common in bladder and gall bladder

What is an edge-shadowing artifact?

when sound waved bend as they hit a curved surface tangentially

What is the most expensive part of the U/S?

probe (transducer)

What is a linear ultrasound probe most commonly used for?

equine tendons

What shape are the ultrasound waves in a linear probe?

straight line

What is a curvilinear ultrasound probe most commonly used for?

thorax and abdomen

What shape are the ultrasound waves in a curvilinear probe?

sector

What is the outcome if you increase the frequency on an ultrasound?

greater resolution, less depth

What is the outcome if you decrease the frequency on an ultrasound?

less resolution, greater depth

What can you measure in real-time imaging (doppler mode)?

can measure movement (heartbeat), can assess direction of flow (leaky valve)

What does the computer do in a CT?

reconstructs the data acquired from the detectors to make a "slice" image

What does tomography do?

2D slices to allow 3D location

What is CT images in horses "generally" limited to?

head, carpus/tarsus, digit

What do you need to do when CTing soft tissues?

inject contrast solution

What are some indications with CT?

detailed evaluation of bone (fracture planning), image the head, spine, abdomen, etc.

How do MRIs work?

strong magnet applied and protons are excited by a radiofrequency pulse; pulse removed --> protons relax --> emits signal; protons in different tissues relax differently

Both MRI and CT allow for __________ and ____________

tomography; 3D reconstruction

What does MRI have thats better than CT?

contrast resolution

What is an MRI superior for imaging?

soft tissues

What is CT superior for imaging?

bone because it doesn't have as much water

Which imaging technique is superior for fracture planning?

CT

Where is an ultrasound not possible in a horse?

the foot

What are the indications for MRI in small animal?

neuroimaging, musculoskeletal, tumor staging, abdomen and cardio

What are the excellent modality's for soft tissue?

ultrasound, MRI

What is the excellent modality for bone?

CT

What are the good modality's for bone?

radiograph, MRI

What can an ultrasound detect on bones?

edge only

What modality's can do 3D?

CT, MRI