Topic 40 - Principles, methods and diagnostic value of ultrasonography.

Question 1

Principles of RADIOGRAPHY:

Answer 1

• Overview of the whole abdomen and the bony structures
• Imaging depends on the density of the organs

Black = fluid
White = bone
Grey = tissue

Question 2

Principles of ULTRASONOGRAPHY:

Answer 2

1. Image only one section at the time
2. Imaging depends on the acoustic properties of the organs
3. The more sound reflected the brighter the US image
4. Fluid filled organs contain no or few reflectors producing no echo = black
5. US allows accurate distance measurements
6. The image is updated continuously, allows observation for moving organs - heart

Question 3

Finding diseases with ULTRASONOGRAPHY, principles:

Answer 3

1. Disease process may change size, shape and internal structure of the organs and these can be detected with US
2. US can not replace histological examination, instead allows establishing diagnosis by localizing lesions and aiming histological sampling - biopsy, centesis

Question 4

Indications for US:

Answer 4

• Palpable alterations in the abdomen
• Laboratory alterations
• Clinical signs without palpable or laboratory alterations

Question 5

ultrasonography is done by an operator, what makes an operatory a good one?

Answer 5

• knows normal topography well
• knows normal US anatomy of organs
• knows the physics of US, the origin of different artifacts
• performs meticulous examination of the organs indifferent planes
• knows the different pathological processes and and the possible US alterations they may cause
• knows the differential diagnosis of the different US alterations

Question 6

Sound frequency of the US:

Answer 6

2-18 MHz (megahertz)

Question 7

Sound frequency a human can hear:

Answer 7

20 Hz (hertz) - 20 kHz (kilohertz)