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Flashcards in Intro Deck (66):
1

what are the different MR pulse sequences

spin echo t1 - SE

spin echo t2 - FSE

proton density - PD

gradient echo - GE

Short tau inversion recovery - STIR

2

what are the TR and TE values for spin echo T1

low TR - 380
low TE - 20

3

what are the TR and TE values for spin echo T2

high TR - >1500
high TE - > 80

4

what are the strengths of a T1 MR

what are the weaknesses

strengths - anatomic detail, fat subacute hemorrhage, meniscal pathology, gadolinium use to enhance, marrow pathology is better than other pulse sequences

weaknesses - poor detection of soft tissue edema, not as sensitive stir or T2 for marrow pathology

5

what are the strengths of a T2 MR

what are the weaknesses

strengths - detection of fluid and pathology, act as myelographic study without nee of intrathecal contrast administration

weaknesses - long imaging time (fast spin echo reduces T2 imaging times)

6

FSE and SE corresponds to what on MRI scans

FSE - fast spin echo - T2

SE - spin echo - T1

7

TR and TE correspond to what on MRI scans

TR - repetition time
TE - echo time

8

what are the TR and TE values for proton density pulse sequence for MR

high TR

low TE

9

what are the strengths of proton density MRI pulse sequence

what are the weaknesses

strengths - anatomic detail and meniscal pathology

weaknesses - poor detection of fluid and marrow pathology

10

what are the strengths of gradient echo MRI pulse sequence

what are the weaknesses

strengths - ligaments, tendons, loose bodies, subtle hemorrhage, 3D imaging

weaknesses - poor detection of marrow, metallic hardware increases artifacts on image

11

what are the strengths of short tau inversion recovery MRI pulse sequence

what are the weaknesses

strengths - marrow and soft tissue edema

weaknesses - DONT use with gadolinium, and doesnt perform well with large patients

12

what is the example used in the slide that proton density picks up

what is the example used in the slide that stir picks up

PD - bankhart lesion

STIR - stress fractures on calcaneus

13

what is specialized form of MR that allows non invasive imaging of the CV system

MRA

MR angiograpghy

14

when is MRA used

when angiography is conventional contraindicated

15

what is the best way to examine the vertebral, carotid, and cerebral arteries

MRA > doppler US > conventional angiography

16

what is the best way to detect arteriovenous malformations and aneurysms

MRA > conventional angiography

17

what is the contrast agent used in MR

gadolinium diethylene triamine pentaacetic acid

called gadolinium DTPA

18

what does gadolinium do to the image

enhances the MR signal intensity of tissues following intravenous or intra-articular injection

19

gadolinium is considered what

radioisotope

20

gadolinium (contrast agent) is useful for evaluating what

inflammatory, infection, and neoplastic lesions

21

what are adverse reactions associated with using contrast on MR

when should you not use contrast? values?

anaphylaxis may occur but rare - nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD) is a small but serious risk

patient with kidney disease or low GFR - avoid contrast

GFR < 60 - use caution
GFR < 30 - AVOID

22

when did we first start using CT scans

1972

23

CT is great for what

and bad for what

great for - bony anatomy, complex bones, subtle calcifications, emergency situations, complex areas where motion is an issue

bad for - bone marrow and internal derangement
(just not as good as MR)

24

which imaging system acquires axial image slices

CT

25

what are the contraindications of CT

- utilizing ionizing radiation
- limit use on children
- pregnancy
- contrast - hypersensitivity reaction
- metallic objects
- claustrophobia
- risk of raditaiton vs need for diagnostic information

26

what are the four basic types of contrast used for CT scans

intravenous
oral
rectal
intra-articular

27

what are hounsfield units used for

CT

28

what is an easy way to differentiate the make up of any lesion on a CT scan

hounsfield units

29

what tissue has the highest hounsfield unit

bone - 1000

30

what is a quick and easy way to look at subcutaneous anatomy and certain MSK anatomy

ultrasound

31

what is a bone scan also called

bone scintigraphy

32

what are the indications of a bone scintigraphy

- eval for skeletal metastasis
- early detection of osteomyelitis
- diagnosis of stress and occult fracture
- staging of pagets disease
- diagnosis of osteonecrosis
- eval of fracture and healing
- assess complications of total joint athroplasty
- assess activity of RA and seronegative arthritis

33

what is injected intravenously for a bone scintigraphy

99m tc-mdp

technetium

34

what determines the amount of radiopharmaceutical deposited at the site for a bone scan

based on vascular permeability, blood supply, and osteoblastic activity

- increased bone turnover generally means increased uptake

35

how do you decide between ordering a MRI and bone scan

MRI - is done more quickly (1 hour), scheduled for a sooner date, no radiation, better soft tissue detail, expensive

bone scan - takes longer (4 hours), conveys wider area of the body (bilateral or diffuse symptoms), easier to interpret, cheaper

36

compare bone scan and MRI based on sensitivity and specificity

bone scan - sensitive but not specific

MRI - sensitive and specific

37

what are the 3 basic forms of imaging? what are these forms based on?

based on how the image is formed

transmission imaging
reflection imaging
emission imaging

38

what are the types of transmission imaging

reflection imaging

emission imaging

transmission - radiography, fluoroscopy, CT

reflection - US

emission - MR and nuclear medicine

39

attenuation occurs in what type of imaging

transmission imaging

40

what is attenuation

a decrease in the intensity of beam as it transverses through matter

41

attenuation decreases the intensity of the beam

how so and due to what

absoprtion - photoelectric effect

deflection - compton scatter

42

increase in density of tissue does what to attenuation

increase attenuation

meaning fewer particles make it to the film

43

what is a permanent film record of differential attenuation of xray beams by various tissues

radiograph

44

what transmission method is used in facet joint injection that allows placement of needle directly in the facet joint

fluoroscopy

45

fluoroscopy produces what

still image

46

what is based on sound waves that are sent to the body and then are sent back to the sound head similar to an echo

reflection imaging

47

how does reflection imaging work with low and high densities of matter in the body

low density - water - does NOT reflect sound waves back to sound head

high density - bone - reflects back sound waves back to sound head

48

low density on ultrasound appears? and is considered what

high density on ultrasound appears? and is considered what

low density appears DARK --> low echogenicity or hypoechoic

high density appears BRIGHT --> high echogenicity or hyperechoic

49

what type of imaging method is based on various tissues emitting a particular frequency that is detected and mapped by a computer to generate an image

emission imaging

50

what imaging method uses natural magnetic properties of atoms to produce a image

MRI

51

what imaging method detects gamma ray emissions from the body after radioisotope is injected

nuclear medicine

52

what are the definite clinical indicators of imaging

red flags

trauma new or old
weight loss
night pain
neuromotor defecit
inflammatory arthritis
hx of malignancy
fever of unknown origin
abnormal blood work
deformities of the spine
failure to respond to therapy
medicolegal complications

53

what are the possible clinical indications of imaging

yellow flags

>50 years old
pediatric patient with pain and no trauma
drug and alcohol abuse
corticosteriod use
unavailable imaging
lost or outdated imaging
dated previous studies
research - need IRB
constitutional systemic DZ
recent immigration
therapeutic risk assessment - downs syndrome

54

what are the non indicators of medical imaging

patient education
routine screeening
habitual screening
discharge status assessment
pre employment screening
inadequate equipment
non trained person CA
financial gain
recent hx of radiation
pregnancy

55

who do you consult to know what type of imaging to order in any given situation

american college of radiology appropriateness criteria

56

in many circumstances what is the first step in the diagnostic imaging process

why

plain film radiography

cheap, easy, available, quick, high diagnostic yield

57

what imaging method is good for MSK, abdominal, and chest pathology

xray

58

what are xray contraindications

children and pregnancy

59

what is the ALARA principle

as low as reasonably achievable

60

what are the ABCS

alignment
bone
cartilage space
soft tissue

61

xray use is declining because it has been proven to have little use for the following....

spine assessment for LBP
sinus infections
kidney stones
kidney function
abdominal pain
skull injuries

what methods are better for each

spine assessment for LBP - MR

sinus infections - CT

kidney stones - CT

kidney function - US, MR, nuclear medicine

abdominal pain - CT or MRI

skull injuries - CT

62

when should you order advanced imaging

failure to respond to therapy

need more specific diagnosis

documentation of subtle injury or pathology

pre surgical planning or assessment

if evaluation suggests further imaging

if $ can be saved for the patient

63

MRI is great for what

and bad for what

great for - internal joint derangement, MSK soft tissues, bone marrow

bad for - calcification, bony fragments, anatomy that can be obscured by motion (gut)

64

what are the characteristics of MRI

radiation?
used for what?
how many planes?
cosst?

no radiation

soft tissue and bone detail

multiplanar imaging

expensive

65

what are MR contradindications

1st trimester pregnancy
>300 lbs
clasutrophobia

ferromagnetic artifacts
pacemakers, defibrillators, implanted NTs or tens units

implants and prosthetic heart valves
breast feeding women - may be ok but must pump 24 hours before feeding child

66

how does MRI work

atomic nuclei spin randomly in the body

magnet aligns the H nuclei parallel with the magnetic field

radio signal activated, nuclei misalign, radiosignal stops, nuceli realign, nuclei release a signal

coil recieves the signal like a radio atenna

computer generates an image