Redo of US, CT, MRI Better

Bottom line

Acoustic shadow

Anechoic

Echogenic

What does the doppler pobe tell you?

What fluid is traveling towards you and what is away from you

Red is towards. Blue is away

What on US can help you identify a thrombus?

Doppler

What technology does echocardiograms use?

Ultrasound

What is M-mode?

It lets you graph out a tissue over time with an ultrasound. Useful for examining the heart with echocardiogram

What is nuclear scintigraphy?

Inject radioactive drug to target a specific ACTIVE tissue. Camera can be used to detect areas of increased metabolic activity like infection or neoplasia

What is the usefulness of nuclear scintigraphy?

Functional imaging that is highly sensitivity but has a low specificity

Describe the view of nuclear scintigraphy

Not cross sectional

Poor spatial and contrast resolution

What imaging modality has the best spatial resolution?

Radiographs

What imaging modalities use x-rays?

Radiographs and CT

How are radiographs formed?

x-rays

What is the risk of x-ray exposure?

Stochastic and deterministic effects

What is the indication for a radiography?

Usually a first line of defense for imaging

What are the limitations of a radiograph?

Making 3D animals into 2D images causes superimposition

Border effacement occurs due to soft tissue and fluid having the same opacity or because two soft tissue opacities are next to each other

What imaging modalities removed superimposition?

Ultrasound, MRI, and CT because they are cross sections

What does ultrasound have the best contrast resolution for?

Soft tissue

What is the spatial resolution of ultrasound?

Good, but not as good as radiographs

How does ultrasound form images?

Sending out soundwaves and letting them bounce back

What is acoustic impedance?

Difficulty for a soundwave to go through a tissue

What is the reason why bone is not visible on ultrasound?

The acoustic impedance is really high

What is acoustic shadow?

Area deeper than bone on ultrasound that is just black

What does anechoic mean?

Term for when sound waves do not bounce back on ultrasound

What does echogenic mean?

Term for when sound waves do bounce back

What is a dynamic imaging technique?

Ultrasound

What are the limitations of ultrasound?

Lots of training and limited views

What opacities are limited with ultrasound?

Bone and gas

What do you use for contrast with MRI?

Paramagnetic IV materials like gadolinium

What is MRI best for?

Soft tissues like brain and spine

How does MRI work?

Uses magnetic resonance and radiofrequency

What is the safety of MRI?

Extremely strong magnetic field formed by a superconducting magnet makes it impossible to have metal nearby

What term do you use for MRI instead of opacity?

Intensiry

What are the limitations of MRI?

Takes 30 or 90 minutes so always needs general anesthesia

Why is CT able to differentiate soft tissue from liquid?

Liquid is more hypoattenuated than soft tissue with CT

What contrast agent do you use for CT?

Iodinated agents like iohexal

What is dose of CT?

100x that of an xray so more risk for stochastic and deterministic effects

What term is used instead of opacity in CT?

Attenuation

What are the indications for a CT?

Trauma, met check, vascular shunt, bony disease, non neurogenic skull problems

What are the limitations of CT?

Only takes 30ish seconds but still usually needs general anesthesia or a heavily sedated patient