Cross Sectional Anatomy

CT is an ____________ radiation source

CT is an ____________ radiation source

ionizing

computer generated image of attenuation from 360 different points

CT

basic unit of CT

houndsfield

MR does not use

ionizing radiation

orients hydrogen atoms in a magnetic field

MRI

sound beam of high frequency is passed through the body

Ultrasound

Transmitter and receiver for ultrasound

transducer

_______ is not a good conductor for ultrasound

air

excellent conductor in ultrasound

water

measurements for ultrasound

always metric

always give measurements in

two dimensions

ultrasound is used to describe

texture of tissue as it reacts to the ultrasound beam

without echoes

anechoic

shows some echoes and has good through transmission

hypoechoic

has echoes

echogenic

shows lots of echoes and does not have much through transmission

hyperechoic

homogenous - same echo pattern throughout

isoechoic

attenuation of sound beam

shadowing

MR image where fat is bright

T1

MR image where water is dark

T1

Mr image where water is bright

T2

Mr image where fat is dark

T2

flowing blood is called a

signal void

low frequency is used for

deeper structures

organs that use low frequency (more penetration)

liver gallbladder kidneys

high frequency is for

superficial structures

structures seen using high frequency

thyroid breast

___________is NOT a good conductor for ultrasound

AIR

cuts the body from superior to inferior

axial / transverse

anything without echoes

anechoic

describe anechoic

totally black - sonolucent good through transmission smooth borders

examples of anechoic

cysts vessels renal pyramids

has some echoes and good through transmission (a little darker)

hypoechoic

has echoes

echogenic

has lots of echoes and is brighter than surrounding tissues. not much through transmission

hyperechoic

_________ has brighter walls and is hyperechoic

arteries

arteries are _________

hyperechoic

____________ are anechoic and have a very thin muscle layer

veins

same echo pattern throughout

isoechoic / homogenous

attenuation of the sound beam causes

shadowing

all gallbladders should be

anechoic

anything that moves and has a shadow is a

stone