What is the use of ultrasonic waves directed through the heart to study its structure and motion? myocardial perfusion imaging

Echocardiography

Explanation:

Echocardiography is a painless test that uses the sound waves called ultrasonic waves with a frequency exceeding 20 kHz is used to produce images of the heart.

The echocardiography is also known as the ultrasound of the heart which is performed to check the blood clots, the aorta related pictures and the functioning of the valves of the heart.

The picture produced by this echocardiography is known as the echocardiogram and is used to treat heart disease.

Thus, Echocardiography is the correct answer.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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