Introduction to Diagnostic Imaging

Question 1

how many radiographic opacities are there?

Answer 1

five

Question 2

are radiographs sensitive for bone loss?

Answer 2

no

Question 3

what are mach lines?

Answer 3

when it looks like there is a fracture when there is not

Question 4

what physical properties are responsible for x-ray attenuation?

Answer 4

atomic number
physical density
thickness

Question 5

how do we triangulate to deal with squishing 3D into 2D?

Answer 5

two images that are perpendicular

Question 6

what are iodine and barium usually used to evaluate?

Answer 6

lumens and cavities

Question 7

how do we describe filling defects?

Answer 7

intraluminal
mural
extramural

Question 8

where is barium used and when should it not be used?

Answer 8

gastrointestinal tract almost always
do not use in cases of suspected gastrointestinal perforation

Question 9

where can iodine be given?

Answer 9

almost anywhere

Question 10

why would you give iodine intravenously for contrast media?

Answer 10

angiogram
intravenous urogram
portogram

Question 11

what are the positives and negatives of contrast procedures?

Answer 11

improve contrast
help assess function
do not eliminate superimposition

Question 12

what are the methods of tomographic alternate imaging?

Answer 12

computed tomography
magnetic resonance imaging
ultrasonography
(nuclear medicine)

Question 13

what are the advantages of multislice computed tomography?

Answer 13

tomographic: no superimposition
better tissue contrast
can do reconstructions
can cover large areas
relatively fast
can do contract procedures
can give IV contrast
CT guided biopsy
can use for radiation therapy planning
great for bones, lung

Question 14

can computed tomography tell soft tissues apart?

Answer 14

yes

Question 15

why is it necessary that you can manipulate the CT display to best show the tissue of interest?

Answer 15

human eye can only distinguish a limited number of shades of grey

Question 16

what do you need in order to get enhancement using IV iodinated contrast?

Answer 16

tissue of interest must have vascular supply
in neural tissue, must have loss of blood-brain barrier

Question 17

what are the uses of using CT for IV iodinated contrast?

Answer 17

evaluate vessels
assess vascularity of lesion
assess viability of tissue
asses blood-brain barrier

Question 18

what are the disadvantages of computer tomography?

Answer 18

expensive $1500
lower availability than radiographs
requires anesthesia
use of x-rays still limits tissue contrast resolution
radiation dose higher than radiographs
imaging does not occur in real time
dense bone and metal give artifacts

Question 19

what are the advantages of magnetic resonance imaging?

Answer 19

tomographic
multiplanar (can image in any plane)
excellent soft tissue contrast
no ionizing radiation
can cover large areas
special sequences (allows better characterization of tissues)
can do angiography without a contrast medium

Question 20

what is T1W SE magnetic resonance sequence characterized by?

Answer 20

fluid dark
fat bright

Question 21

what is T2W SE magnetic resonance sequence characterized by?

Answer 21

fluid/fluidy tissues bright

Question 22

how do lesions often appear on T2-W sequences?

Answer 22

hyperintense or bright

Question 23

what is signal void/black on all sequences of MRI?

Answer 23

no H+

Question 24

what does the relative signal strength mean on all sequences?

Answer 24

intensity
hypointense: dark

Question 25

what do you need for MRI contrast with IV gadolinium?

Answer 25

vascular supply blood-brain barrier breakdown in CNS

Question 26

what does IV gadolinium do?

Answer 26

paramagnetic agent shortens T1 relaxation at low concentrations

Question 27

what are the disadvantages of MRI?

Answer 27

expensive lower availability requires anesthesia requires radiologist at time of scan scans take more time prone to artifact needs hydrogen protons magnet is always on

Question 28

why is MRI not good for lungs?

Answer 28

long scan times lead to motion artifact too few H+ in aerated lung to generate an image

Question 29

what are the advantages of ultrasonography?

Answer 29

tomographic multiplanar relatively cheap fairly quick available no anesthesia required good soft tissue contrast real time imaging allows guided biopsy no ionizing radiation can evaluate vessels useful artifacts good for abdominal organs, especially GI

Question 30

what does hyperechoic mean?

Answer 30

bright

Question 31

what does isoechoic mean?

Answer 31

equally echogenic

Question 32

what is the doppler effect in ultrasound?

Answer 32

moving reflectors (red blood cells) generate echoes with a different frequency from the incident beam (doppler shift)

Question 33

what can the computer calculate using the doppler shift?

Answer 33

direction of flow velocity of flow presence or absence of turbulence

Question 34

what is important about ultrasound artifacts?

Answer 34

sometimes useful can allow ultrasonographer to make an educated guess about the makeup of the structure strong or black shadows deep to an object usually mean mineral dirty or grey shadows often means gass "fair enhancement" usually means the structure is fluid filled

Question 35

what are some disadvantages of ultrasonography?

Answer 35

cannot image through gas, intact bone or metal cannot cover large sections of the patient at once does not give a global view cannot do reconstructions highly user dependent hard copy difficult for others to understand

Question 36

can you penetrate aerated lung using ultrasonography?

Answer 36

no

Question 37

when can you image diseased lung?

Answer 37

only if no aerated lung is between the chest walls and the area of interest

Question 38

what is nuclear medicine?

Answer 38

radioactive isotope given to the patient detect emissions from patient to generate image

Question 39

what are the advantages of nuclear medicine?

Answer 39

relatively inexpensive gives information on function global view- can cover whole patient high sensitivity

Question 40

what are the disadvantages of nuclear medicine?

Answer 40

radiation dose to patient patient radioactive following the study does not give good morphologic information low specificity

Question 41

what is the radiation dose in nuclear medicine compared to radiographs?

Answer 41

bone scane 31x 3-view chest radiographs dose

Question 42

why do we use MRI over radiographs?

Answer 42

better for neural tissue/soft tissues

Question 43

why do we use CT over radiographs?

Answer 43

better for bone/thorax

Question 44

why do we use ultrasonography over radiographs?

Answer 44

better for gastrointestinal/abdominal regions

Question 45

why do we use nuclear medicine over radiographs?

Answer 45

better for function

Question 46

how does an MRI make an image?

Answer 46

radiofrequency wave absorption and electromagnetic induction

Question 47

what are the positives of radiography?

Answer 47

relatively cheap available gives global view can do most without anesthesia (not skull or spine) most people can interpret

Question 48

what are the disadvantages of radiography?

Answer 48

3D squashed into 2D limited opacities: only 5, cannot see inside soft tissue organs, insensitive for bone loss patient receives radiation

Question 49

why would you give iodine intrathecally?

Answer 49

myelogram

Question 50

why would you give iodine into the urinary tract?

Answer 50

cystogram urethrogram

Question 51

why would you give iodine into joints?

Answer 51

arthrogram

Question 52

why would you give iodine into the gastrointestinal tract?

Answer 52

if perforation is suspected

Question 53

why would you give iodine into wounds and fistulas?

Answer 53

to find the extent

Question 54

what reactions does barium cause outside of the gastrointestinal tract?

Answer 54

granulomatous

Question 55

what makes up multislice computed tomography?

Answer 55

rotating X-ray tube and electronic detectors computer represents each slice of a patient as a grid of small units of volume (voxels) and calculates the amount of x-ray attenuation by each voxel

Question 56

how is a magnetic resonance imaging image generated?

Answer 56

put patient in strong magnetic field use radiofrequency pulse to cause H protons to precess this generates a current in a receiving coil computer forms an image

Question 57

what is dark in T2*W gradient echo in MRI?

Answer 57

hemorrhage and mineral

Question 58

what is the FLAIR MRI sequence like?

Answer 58

pure fluid dark, fluidy tissue bright

Question 59

which sequences do lesions appear hyperintense or bright on?

Answer 59

T2-W except those with mineralization, bone, hemorrhage, fat, melanin

Question 60

what color does FAT SAT make fat?

Answer 60

dark like T1W but fat not bright

Question 61

on what sequences does IV gadolinium appear bright?

Answer 61

T1-W spin echo and FAT SAT

Question 62

are the pituitary gland and meninges inside or outside of the blood brain barrier?

Answer 62

outside

Question 63

what are hydrogen protons bad for?

Answer 63

cortical bone and lung

Question 64

what do dirty or grey shadows on ultrasound often mean?

Answer 64

gas

Question 65

what do strong or black shadows on ultrasound often mean?

Answer 65

mineral

Question 66

what does far enhancement usually mean on ultrasound?

Answer 66

structure is fluid filled