2012年9月7日 星期五

Doppler Ultrasound Imaging


Ultrasound imaging - also referred to as sonography is a medical procedure often carried out in hospitals using high frequency sound waves to map images within the body.

Ultrasound is a non invasive procedure and unlike Xray which uses potentially harmful ionizing radiation, ultrasound is a virtually risk free procedure which is why it is used routinely to scan images of unborn babies.

The other additional benefit of ultrasound is that it captures images in realtime and can show movement within the body, making it ideal to monitor bloodflow within the body.

General ultrasound images are produced in 2d but advances in the technology have meant that images can now be processed in 3d and in some very special instances 4d (movement is recorded)

Doppler Ultrasound Doppler ultrasound is a specialised technique which evaluates the flow of blood around the body as it moves through the body's major veins and arteries.

Currently 3 types of doppler ultrasound are used by physicians.

Colour vascular doppler uses doppler measurements to create a colour pattern which describes the flow of blood through the blood vessel it is measuring.

Power doppler is used to give detailed information of blood flow within deeper blood vessel - located within organs in the body.

Spectral doppler displays doppler measurements graphically instead of using colour patterns.

Common Ultrasound Procedures Ultrasound scanning has a wide spectrum of medical some very common uses for it are to diagnose swelling and infection within the body.

It is also extremely well suited to examining internal organs including:

o heart, liver, gallbladder , spleen, pancreas, kidneys, bladder uterus, ovaries, eyes, thyroid

o Another use for Ultrasound scanning is for guiding a needle thought the body during biopsies (to extract a sample of body cells).

Common Doppler procedures

Some routine doppler ultrasound procedures are:

o Evaluate blockages within blood vessels (blood clots) Evaluate the narrowing of blood vessels caused by plaque

o This information can be used to determine whether a patient would be suitable for a procedure like angioplasty.

What to do if you are having an ultrasound examination

Loose fitting clothing should be worn if you are about to have an ultrasound examination, your physician will ask you to remove your clothes and any jewellery and you will be wear a gown when the procedure is taking place.

In some more specialised ultrasound examinations your doctor may tell you not to eat or drink for a period before your examination. But generally this is not the case for routine examinations.

What does ultrasound equipment look like? An ultrasound scanner consists of a computer and video display, the actual transducer that scans the body looks a bit like a microphone which is attached to the computer console by a cord.

The transducer sends out sound waves and records the returning echo which is then used to create the image. The basic principles are the same as sonar used in submarines and ships.

The great thing about ultrasound imaging is that the image is immediately viewable on the video screen so there is no lag between taking the image and developing it which is the case with xray.




This article has been written by Ross Fraser and talks about doppler ultrasound scanning





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