Ultrasound

History of Ultrasound First introduced to medical world in 1950s However, has its beginnings in the 1880s when Pierre Curie introduced simple echo sounding methods. This led to the discovery of SONAR -(Sound Navigating and Ranging)

SONAR, the technique of sending sound waves through the water and observing the returning echoes to characterize submerged objects inspired early ultrasound investigators. Shortly after WWII, researchers in Japan began to explore medical diagnostic capabilities of ultrasound.

The US and Europe became aware of this new diagnostic technique in the 1950s when Japan presented their findings on the use of ultrasound to detect gallstones, breast masses, and tumors. US pioneers contributed many innovations and important discoveries to the field in the following decades.

Also produced was a hand-held “contact” scanner for clinical use. Early 1970s Gray scale static images of internal organs Mid 1970s Real-time imaging Early 1980s Spectral Doppler Color Doppler Also produced was a hand-held “contact” scanner for clinical use.

In the 1980s, after all these innovations, ultrasound technique was technologically more advanced than computers. Because of this, Samuel H. Maslak developed the 128-channel Computed Sonography platform. This allowed for black-and-white and color ultrasound images with superior resolution and clarity. 1996 – Acuson Corp. developed the Sequoia 512 system.

Although ultrasound is better known for its diagnostic capabilities, it was initially used for therapy rather than diagnosis. In the 1940s, ultrasound was used to perform services similar to that of radiation or chemotherapy now. Ultrasonic waves emit heat that can create disruptive effects on animal tissue and destroy malignant tissue.

Principles of Ultrasound: Its Components Operations Applications

Components Transducer Probe Transducer Pulse Controls CPU Display Keyboard/Cursor Disk Storage Device Printer

Physics of Ultrasound Transducer Probe ‘Mouth and Ears’ of the machine. Piezoelectric Effect Discovered by Pierre and Jacques Curie Application of electric currents changes the shape of the crystals, which in turn propagate sound waves. Receipt of sound waves changes shape of crystals again, which emit electrical signals.

Uses of Ultrasound Detection of tumors (Oncology). Assesment of the development of fetus (OB/GYN). Evaluation of blood flow (Cardiology). Insertions.

Ultrasound in Obstetrics and Gynecology

Ultrasound is extensively used in obstetrics and gynecology as a safe, non-invasive, accurate, and cost effective tool to look at the fetus. No set number of scans, but recommended that normally the woman have 2 to 3.

1st scan at 7 weeks: confirm pregnancy, exclude ectopic or molar pregnancies, confirm cardiac pulsation, and measure the crown-rump length for dating 2nd scan at 18-20 weeks: look for congenital malformations, exclude multiple pregnancies, verify dates and growth, placental position (or at 13-14 weeks to diagnose Down Syndrome).

3rd scan at 34 weeks: evaluate fetal size and assess fetal growth, verify fetal position

Technique The woman’s abdomen is covered with a gel so that the transducer can see through the skin real- time scanners (frequency sound waves between 3.5 and 7.0 megahertz) can give a continuous picture of the moving fetus The transducer is placed in contact with the abdomen and moved about to look at different parts of the uterus. Several ultrasound beams scan the fetus in thin slices, which are recomposed into a picture on the monitor screen

What ultrasound detects verify intrauterine implantation to exclude ectopic pregnancy, to diagnose a missed abortion, to establish gestation age and due date, and determine if there are multiple embryos

First trimester markers for chromosomal abnormalities are used to detect Down syndrome Hydrocephalus, anencephaly, myelomeningocoele, dwarfism, spina befida, exomphalos, gastroschisis, duodenal atresia, and fetal hydrops can be diagnosed before 20 weeks

four and a half weeks the gestational sac can be visualized, by five weeks the yolk sac, and by five and a half weeks the embryo can be visualized and measured Doppler ultrasound can detect a visible heart beat and blood flow in fetal blood vessels by six to seven weeks crown-rump length measured 7 to 13 weeks and gives an accurate estimation of gestational age, biparietal diameter, the diameter of the head, measured after 13 weeks, femur length at 14 weeks

cleft lips/ palate, spina bifida, polydactyl, low-set ears, facial dysmorphia, and clubbing of feet

Ultrasound Tools Traditional 2-D 3-D 4-D or dynamic 3-D scanners Transvaginal scanning

Images http://www.obgyn.net/us/us.asp?page=gallery/gallery http://3dultrasound.ucsd.edu/gallery.html http://www.ob-ultrasound.net/goodwork.html

Safety and Risks

Unlike X-rays, ultrasound involves only sound waves No radiation danger However, sound waves can increase body temperature This is known as cavitation Significant only for long exposure time

Many studies have been conducted to determine the physiological effects of ultrasound cavitation No direct correlation has been found between ultrasound imaging and cancer, low birth weight, dyslexia or delayed speech development Reliable data from ultrasound techniques is hard to come by Additional studies are ongoing Biggest risk is misdiagnosis

Future of Ultrasound Improved clarity for use in cancer diagnosis Increased therapeutic use to correct blood clots and kidney stones Portability and veterinary use Joint and muscle treatment through cavitation