Ultrasound & other modalities

Sound waves are measured in —-

Hertz (Hz)

What are the pros and cons of ultrasound?

Pros:

• Noninvasive

• Detects size, shape, and position of organs

• Some distinction of the texture of organs

• Dynamic nature of some organs (eg: motility of the bowel)

Cons:

• Not friendly with gas or bones

• Patient limits

Transducer (probe)

• Piezoelectric crystal

• Converts electrical energy to sound energy

• Once the echo returns it converts the sound energy back to electrical energy

What is the basic principle of ultrasound?

• Production of sound wave from electronic signal

• Sound wave interacts with tissue interfaces and within tissue

• Some sound waves are:

  • Reflected (Echoes)

  • Transmitted

  • Alter direction

• Echoes returning to machine are analyzed and are converted into an image

What are the transducer types?

• Curvilinear

• Linear

• Microconvex

• Phased

Curvilinear

• Pie shaped image

• Useful in areas that are deeper

• Variable frequencies and size

• E.g standard sized dogs

• Less detail

Linear

• Rectangle shaped image

• Used in small animals where we want to zoom in on small structures

• More detail

• Tend to be higher frequency

• e.g cats

Increasing frequency →

decreases penetration

Decreasing frequency →

increases penetration

Sagittal image

• Cranial to the left

• Caudal to the right

• Ventral at the top of image

• Dorsal at bottom of image

Sagittal

Hyperechoic

(very bright) strong reflection

ex. bone, fat, calcifications, scar tissue

Transverse

Isoechoic

(same brightness): blends with surrounding tissues

Hypoechoic

(darker): weaker reflection

ex. many soft tissues

Anechoic

(black): no echoes

Example: fluid (like cysts or blood vessels)

What are the 4 transducer maneuvers?

Fanning, rocking, sliding, rotating

Liver

Kidney

Spleen

Urinary bladder

Small intestines