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Flashcards in PPT info Deck (12)
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1

Ultrasound (method, contrast, measurement, contraindications, cost, time, advantages)

Method: sound waves provide real time images
Contrast: none (no radiation - good for pregnancies and children)
Measurement: echo, flow of fluids (unique)
Contraindications: gas, if you need to see bones
Cost: medium
Time: medium (15-30 min)
Advantages: no radiation (good for pregnancy and kids), can be done at bedside

2

Ultrasound (how do certain tissues appear)

hyperechoic (white) - calcium, air, fat, bone
hypoechoic (gray) - soft tissue
anechoic (black) - fluid

3

MRI (magnetic resonance imaging; method, contrast, measurement, contraindications, cost, time, advantages, disadvantages)

Method: magnetic field excites water molecules; radio waves
Contrast: gadolinium sequences injected via IV
Measurement: intensity
Contraindications: magnetic objects
Cost: highest
Time: longest
Advantages: best tissue discrimination, good for brain/bone, no radiation
Disadvantages: patient can't move

4

CT (computed tomography; method, contrast, measurement, contraindications, cost, time, advantages, disadvantages)

Method: enhanced xrays
Contrast: iodine via IV
Measurement: density using Hounsfield numbers
Contraindications: iodine allergy, renal function
Cost: medium-high
Time: medium
Advantages: better discrimination than xray
Disadvantages: high radiation dose; can't always penetrate BBB

5

CT (densities; how do certain tissues/fluids appear)

air - hypodense; dark (-1000 H.U.)
fat - hypodense; dark (-10-100 H.U.)
fluid - hypodense; black (0 H.U)
bone/tissue - hyperdense; white (+1000 H.U.)

6

plain xray (method, contrast, measurement, contraindications, cost, time, advantages, disadvantages)

Method: radiation
Contrast: barium fluoroscopy
Measurement: density
Contraindications: none
Cost: low
Time: Low
Advantages: done at bedside, quick
Disadvantages: medium radiation exposure, limited discrimination of tissue

7

xray (densities; how do certain tissues appear)

Low (black) => high (white)
1. air (dark)
2. fat
3. soft tissue
4. bone
5. metal (white)

8

nuclear medicine method

- gamma ray radiation (radionuclide isotopes injected IV or inhaled)
- isotope accumulates in particular organ (can be used to study function)
- use a gamma camera to scan the body/organ -> image

9

abnormal radionuclide accumulation (nuclear medicine)

bone scan - bone metastasis
VQ ventilation perfusion lung scan - pulmonary embolism
PET scan - increased tissue metabolism in cancer

10

MRI T1 (intensities)

air - hypointense; dark
fat - hyperintense; bright
fluid - hypointense; dark
bone - hypointense; dark

11

MRI T2 (intensities)

air - hypointense; dark
fat - isointense; gray
fluid - hyperintense; bright
bone - hypointense; dark

12

what dosage has risk for radiation induced cancer?

above 100 msV