Ultrasound or Ultrasonogram, refers to use of sound waves of ultra high frequency 2 million to 20 million Hertz (cycles per second) in 2 to 20 MHz to perform imaging.
USG Probe: Ultrasound scanner has a specialised tranducer made of piezoelectric crystals capable of producing such ultra high frequency sound waves.The tranducer is also refered to as probe.The probes commonly used are curvilinear probe, linear probe , endoraginal probe and endorectal probe.
USG coupling gel: The interface between the tranducer/problems is filled by air which can reflect the ultrasound waves emergency from the probes.To circumvent this a coupling gel is used. The tranducer, coupling gel and skin have same acoustic impedance.
Echogenicity : The appearance of various structures or an USG are referred in terms of ecnogenicity as
1.hyperechoic – reflect sound waves
2.hypoechoic. – partly reflect sound waves
3.anechoeic – absorb sound waves or transmit
Posterior Acoustic Enhancement & Shadowing :
Increased brightness seen beyond objects that transmit a lot of sound waves is referred to as posterior acoustic enhancement. – Area beyond fluid filled cysts display posterior acoustic enhancement.
Posterior Acoustic shadowing:
Decreased brightness seen beyond objects that reflect major part of sound waves impinging on them.
Tissues lying beyond gall stones exhibit posterior acoustic shadowing.
Doppler in Ultrasound:
Doppler USG makes use of doppler shift i.e. the variation in the frequency and wavelength of returning sound waves after impinging on a moving object.
Doppler finds its application in detecting of vascularity of masses, direction of blood flow in vessels, to rule out obstruction in blood vessels, to detect perforator incompetence etc.
Ultrasound Free Image Collection:
A collection of royalty free ultrasound images.
Screening for Abdominal Aortic Aneurysm
DOPPLER ULTRASOUND in Pregnancy
Ultrasound Video Processing for Quantitative Analysis of Fetus
First Trimester Ultrasound USAFP
Ultrasonography in Pregnancy
Fetal Wellbeing and Antenatal Monitoring – ANTEPARTUM FETAL MONITORING
The Role of Ultrasound in Obstetric and Gynaecology
Middle Cerebral Artery Doppler
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