Foundations: Ultrasound (FINISH - add comparison/last slide)

What is an ultrasound?

1. Cross-sectional imaging method

2. Sound waves (ultrasound beam) reflected by a transducer

3. Ultrasound beam bounces off body tissues

4. Return sound waves detected by a transducer• Transducer converts acoustic to electrical signals• Signals are processed by a computer into an image

What are different ways in which ultrasound can be used?

1. Diagnostic

2. Rehabilitative

3. Interventional

4. Research

What is diagnostic US?

Diagnosis and monitor pathology

- Hemarthrosis

- Sprains

- Strains

- Healing stage

- Lesions

- Disease

What is rehabilitative US?

Evaluate muscle and other soft-tissue structure and function (including biofeedback) during physical tasks

What is interventional US?

Guide percutaneous procedures involving "dry" (acupuncture) or "wet" needling (injection)

What is research US?

Measurement, explore muscle and soft-tissue structure and function

- Develop and evaluate screening tools and interventions

What are different arrays with ultrasound?

1. Linear array

2. Curvilinear array

What is a linear array?

Sound wave goes straight through in a line

- Field of view is as wide as the transducer itself

What is a curvilinear array?

Sound wave goes out in a cone shape

- Deep structures are disproportionately larger

What are different types of interactions between the sound beam and tissues?

1. Absorption

2. Reflection

3. Refraction

4. Scattering

What is absorption?

Sound beams get converted to heat

What is reflection?

Sound beam is reflected at the interface between 2 tissues

What is refraction?

Sound beam changes direction

What is scattering?

Sound beams reflect unevenly

What is hyper-echoic vs hypo-echoic?

1. Hyper-echoic: white

2. Hypo-echoic: dark

What are common uses/strengths of ultrasound?

1. Low cost

2. Portable

3. Visualize structures not limited to orthogonal planes

4. Continuous modification

5. Can manipulate tissues during the test

What are common limitations of ultrasound?

1. Operator skill

2. Does not penetrate bone

3. Waves do not cross air interfaces