5. Ultrasonography - Principles, Indications, Limitations

Question 1

Principles:

Answer 1

High-frequency soundwaves (2-20 MHz)
Electric current sent to piezoelectric material (deform/vibrate)
Propagate through different tissue densities
Time to return + strength of soundwaves
Transducer (electrical <—> mechanical)
High-frequency: Superficial organs (7-18MHz)
Low-frequency: Deep organs (2-5MHz)

Question 2

Interpretation:

Answer 2

Hyperechoic: reflects more soundwaves (bright/white)
Ex. Bones, calcifications

Hypoechoic: reflects less (gray)
Ex. Muscle, tumors

Anechoic: reflects nothing (black)
Ex. Cyst, blood vessels

Acoustic shadowing = Hyperechoic stone + dark shadow
Acoustic enhancement = Anechoic cyst + bright area behind

Acoustic impedance: higher = denser

Question 3

Indication:

Answer 3

First-line: biliary, cardiac, renal, obstetrics, vascular

Interventional: aspiration, biopsy,