Principle of ultrasoundNUR HANISAH ZAINOREN

ULTRASOUND One of the imaging modalites with NO IONIZING RADATIONCan image directly in any body planeSound waves with a frequency of 10-20Hz

PrinciplesUS machines utilize the pulse echo principleUS probe generates pulses of high frequency sound waves --> transmitted into the patient --> echoes returning from various tissue boundaries (interfaces) --> detected by probe --> processed by computer --> visualised as an image on screen

Ultrasound gel

Ultrasound gel is a type of conductive medium that enables a tight bond (acoustic seal) between the skin and the probe or transducer, letting the waves transmit directly to the tissues beneath and to the parts that need to be imaged.

ClinicaL interpretation of ECHOGENICITYThe liver is usally used as the benchmark for echogenicity. *in scrotal US, always compare the two testes*Hypoechoic (darker and black) - Lymph node, GIT, Liver masses Hyperechoic (brighter and white) - Bone, Stone, Fat, LigamentsAnaechoic / sonolucent (clear black; containing few or no echo) - Gall bladder, Bladder, Cyst, Amniotic fluidIsoechoic (similar echogenicities) - Spleen and Liver, Used when speaking of comparisons

Doppler studyWhen an US beam encounters a moving structure, a change in the pitch and frequency of the returning echo occurscalled as "DOPPLER SHIFT"

Image can be generate, giving information about the speed and direction of the moving structure

Types of dopplerColor Doppler Power DopplerSpectral Imaging

Color dopplerThe displayed color identifies the direction of flow as well as the speed of flow

Power Doppler Measures the concentration of moving structuresMore sensitive to low-flow states, but does not allow an evaluation of direction or speed

Spectral imagingEstimation of the diameter of the vessel in which the cells are flowing by calculating the velocity of moving RBCs

ReferencesConcise The Radiology for Undergraduates, Bhushan N. Lakhar, Chandrakant M. Shettyhttp://www.slideshare.net/mobile/cbyrne2014/point-of-care-ultrasound-yperechoic-future-in-medical-schoolhttp://youtu.be/JqVGgq5bE-Y

Thank you.