Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MBBS IV - Supplementary Courses > Diagnostic radiology - CT, MRI > Flashcards

Diagnostic radiology - CT, MRI Flashcards

1
Q

CT vs MRI

  • Radiation
  • Exam time
  • Bone detail
  • Soft tissue detail
  • Contrast
A
  • Radiation
    CT = yes, MRI = No
  • Exam time
    CT = fast (3 min), MRI = Slow (30min+)
  • Bone detail
    CT = good, MRI = poor
  • Soft tissue detail
    CT = poor, MRI = good
  • Contrast
    CT = Iodine-based, MRI = Gadolinium-based
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

CT vs MRI

  • Hemorrhagic stroke Sensitivity
  • Ischemic stroke Sensitivity
A
  • Hemorrhagic stroke resolution
    CT = excellent, MRI = poor
  • Ischemic stroke resolution
    CT = poor, MRI = excellent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

CT vs MRI to evaluate Stroke

  • Availability
  • Stroke induced Infarct sensitivity
  • Stroke induced Hemorrhage sensitivity
A
  • Availability
    CT = good, MRI = fair
  • Stroke Infarct sensitivity
    CT = Poor, MRI = good
  • Stroke Hemorrhage sensitivity
  • CT = Good, MRI = Good
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

CT vs MRI

- Early progression of ischemic stroke

A

MRI can detect early edema changes in ischemic stroke much faster than CT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List 3 sequences of MRI and their indications

A

1) FLAIR (fluid attenuation inversion recovery)&raquo_space;Better detection of lesions, suppress CSF
2) SPGR: Spoiled gradient recalled sequence: T1-weighted, fat attenuation&raquo_space; Better anatomy
3) Diffusion weighted sequence&raquo_space; Functional, observe fluid motion and perfusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Application of MRI sequences on the CNS?

A
  • Brain for acute stroke
  • Spine for myelopathy, radiculopathy
  • Infection
  • Neoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

2 Advantages of MRI + 4 disadvantages of MRI

A

Adv:

  • Excellent soft tissue contrast
  • No radiation risk

Disadv:

  • Limited availability, expensive
  • Slow to perform
  • Incompatible with implants, life support (ferrous metal)
  • Nodular systemic fibrosis from Gadolinium chelates in renal failure patients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Assessment for fitness to use Gadolinium in MRI?

A

Check urine creatinine clearance to avoid Gadolinium chelates in renal failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

MRI

Principle of operation?

A
  • Powerful magnetic fiuld align nuclear magnetixation of hydrogen atoms in water in the body
  • Radiofrequency alter alignment of magnetization> produce rotating magnetic field
  • Scanner detect magnetic field
  • Computer reconstruct images
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Hemorrhagic stroke

  • Territories?
  • Most significant D/dx?
A

Lobar territories: Frontal, temporal, parietal or occipital lobes

D/dx: Arterio-venous Malformations (AVM), common in temporal and frontal lobe, young patients with no Hypertension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Hemorrhagic stroke

  • Territories?
  • Most significant D/dx?
A
  • Lobar territories: Frontal, temporal, parietal or occipital lobes
  • Basal ganglia, Cerebellum, Brainstem

D/dx: Arterio-venous Malformations (AVM), common in temporal and frontal lobe, young patients with no Hypertension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Compare epidural and subdural hematoma:

  • Cause
  • Shape
  • Bone fracture
A
  • Cause
    Epidural = Middle meningeal artery tearing (75%) or Transverse sinus tearing (25%)
    Subdural: Bridging vein tearing
  • Shape:
    Epidural = Lentiform (biconvex)
    Subdural = Crescent
  • Bone fracture
    Epidural = 90%
    Subdural = no usual association
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Compare epidural and subdural hematoma:

  • Cross sutures
  • Cross midline
  • Clinical course and progression
A
  • Cross sutures (Subdural crosses Sutures)
    Epidural: No
    Subdural: Yes
  • Cross midline
    Epidural: Yes
    Subdural: No
  • Clinical course and progression
    Epidural: Rapid deterioration
    Subdural: Chronic progression
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Appearance of blood on CT over time?

A

Initial/ acute = Hyperdense (white)

Late/ chronic = Hypodense (black)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define time for acute, subacute and chronic subdural haematoma

A

Acute = < 1 week

Subacute = 1-3 weeks

Chronic = > 3 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Sensitivity of CT vs MRI in detecting ischemic stroke?

A

MRI: high - 86-100%

CT: Gradually improve sensitivity with time, Poor sensitivity for first 10 days

<1 day = 48%
1-2 days = 59%
7-10 days = 66%
> 11 days = 74%

17
Q

2 main types of vessel occlusion in Ischemic stroke?

A

1) Small artery occlusion (<1cm = lacunar infarct, small hypodense area)
usually at basal ganglia and periventricular white matter

2) Large artery occlusion
MCA, ACA, ICA, PCA, Cerebellar or brainstem infarct

18
Q

Range of Hounsfield units/ CT number in Bone, Clotted blood, gray matter, white matter, CSF, Water, Fat, Air

A

Hounsfield unit:

  • Water = 0
  • Fat = -20 to -100
  • Air = -1000
CSF = 0-8 
White matter = around 30
Gray matter = around 40
Clotted blood = 40-95 
Bone = 80 - 1000
19
Q

Multiple/ large number of lesions on CT suggests?

A

Metastasis

Disseminated infection

20
Q

Outline 5 different shape of lesions and interpretation

A

1) Round/ Oval = slow displacing, growing lesion
2) Tubular = vascular or neural lesion
3) Wedge/ Triangular = Vascular territory affected
4) Polygonal/ plate = fibrosis pattern
5) Irregular/ Infiltrative = malignancy

21
Q

Adverse reactions to iodinated contrast for CT

A
  • Anaphylaxis (increased risk with prior history of contrast reaction, active asthma and allergies)
  • Nephrotoxicity (increased risk with DM, renal impairment, dehydration)
  • Fatal lactic acidosis- Metformin retention due to renal failure induced by iodinated contrast

Must not use metformin with Iodine contrast in CT

22
Q

Name 2 contrasts for CT

Route of admin.?

A

Iopamiro (iodinated)
Water (oral or rectal contrast)

IV, Per-oral, Per-rectal

23
Q

Typical effective dose (mSv) for CT head, chest and abdomen or pelvis

A

Head = 2.3
Chest = 8
Abdomen or pelvis = 10

24
Q

Typical effective dose (mSv) for Barium swallow, meal, follow-through and enema

A 
Swallow = 1.5 
Meal = 3 
Follow-through = 3 
Enema = 7
25
Q

Advantages of MDCT over conventional CT

A

Multi-detector CT

Advantage:

  • Increase coverage with one rotation
  • Improve spatial and temporal resolution
26
Q

Advantage of CT over X-ray

A
  • No superimposition

- 3D reconstruction for spatial resolution

MBBS IV - Supplementary Courses (54 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions