Alternate Imaging Modalities

Question 1

Flouroscopy

Answer 1

real-time moving x-ray of internal structures

Question 2

CT Scanning

Answer 2

series of cross-sectional x-rays
can create 3D images digitally (volume rendering) and multiplanar reconstruction (ex: creating lateral view from cross-sectional images)

Question 3

Pixels vs Voxels

Answer 3

pixels are 2 dimensional (x and y)
voxels are 3 dimensional (x, y, and z) (the lower the z value (slice thickness), the better the resolution)

TEST QUESTION

Question 4

Hounsfield Units

Answer 4

the typical monitor displays 256 shades of gray
the human eye can only differentiate 20 shades of grey

Question 5

Windowing

Answer 5

Wide HU Window: best for tissue types that vary alot
Narrow HU Window: best for imaging similar tissue types

Question 6

CT Terminology

Answer 6

HYPERattenuating: highest HU values, appear white (bone and metal)

HYPOattenuating: lowest HU values, appear black, (air)

Question 7

What are the differences between CT and radiography

Answer 7

CT produces cross-sectional images vs 2D
Ct is more expensive and less readily available

Question 8

Answer 8

hyperattenuating structure

Question 9

Differences between CT and MR

Answer 9

ct is an x-ray procedure using ionizing radiation. MR does not use ionizing radiation

there is no contrast of soft tissue on CT
Ct is fast to acquire and less expense than MRI

Question 10

Answer 10

dilated ventricle is hypointese on T1 weighted images and hyperintese on T2 images

Question 11

Answer 11

degenerative disc before hypointesne

Question 12

What are the important differences between a low frequency transducer and a high frequency
transducer.

Answer 12

A high frequency transducer will provide images of high detail (good spatial resolution) but will
not penetrate deep into tissue
* A low frequency transducer will have good depth penetration to image deep structures but will
have poorer detail

Question 13

What are the differences between ultrasound and radiography

Answer 13

ultrasound does not use ionizing radiation
ultrasound gives soft tissue contrast
US images represent cross sectional images vs 2D

Question 14

Doppler ultrasound will show the direction of flow of blood. By convention, if the blood is moving
toward the transducer the color will be.

Answer 14

red

Question 15

Which modalities use ionizing radiation (x-rays/ gamma rays).

Answer 15

Ionizing Radiation
* Radiography
* Fluoroscopy
* Computed Tomography

No Ionizing Radiation involved in image formation
* Magnetic Resonance Imaging
* Ultrasound

Question 16

What modality would be best to evaluate abdominal organs

Answer 16

ultrasound

Question 17

What modality would be best to evaluate for the presence of a brain tumor

Answer 17

MRI

Question 18

What modality would be best to evaluate location of a bullet within the thorax

Answer 18

CT

Question 19

What would be the best modality to evaluate for a collapsing trachea

Answer 19

Fluoroscopy

Question 20

Main weights

Answer 20

T1 and T2

Question 21

T1 weighted

Answer 21

Fluid is hypointense (black)
fat is hyperintese (white)

Question 22

T1 relaxed

Answer 22

fat - hyperintese (white)
tissues - (intermediate intensity -gray)
water (black)

Question 23

T2 Weighted

Answer 23

Fluid -hyperintense (white)
fat- hyperintense (white)

Question 24

MR Terminology

Answer 24

hypointense - less bright
isointesene -same brightness
hyperintese- brighter

Question 25

Ultrasound frequency

Answer 25

low frequency, low resolution, poor quality, good for large pets

high frequency, high resolution, good image, low penetration, good for small pets

Question 26

US terminology

Answer 26

Anechoic- black
hyperechoic -dark grey
isoechoic- same
hyperechoic- brighter