Feel the Beat
In addition to displaying cardiac anatomy, various medical imaging techniques -- including PET, CT, MRI and echocardiography provide information related to heart function. However, the potential complications with the use of contrast agents as well as the cost of these imaging methods are limiting factors for their widespread clinical application, and none of these methods can "see" the heart as it stiffens and softens with each beat.
Did you know?
The average heartbeat is 72 times per minute. In the course of one day it beats over 100,000 times. In one year the heart beats almost 38 million times, and by the time you are 70 years old, on average, it's made it to 2.5 billion beats. Carl Bianco, How Stuff Works: How Your Heart Works
Biomedical engineering Professor Gregg Trahey's group has shown that a special form of ultrasound, called Acoustic Radiation Force Impulse (ARFI) imaging, has promise for real-time viewing of the heart in action. The method monitors the heart's relaxation and contraction based on telltale changes in the organ's stiffness. Shifts in those properties can be an indication of heart failure and can also vary with cardiac ischemia or following a heart attack, among other cardiac conditions. The National Institutes of Health-funded work appeared in Ultrasound in Medicine & Biology.
The ARFI method, which Professors Trahey and Kathy Nightingale pioneered beginning in 1997, employs two different sound pulses: a high-energy beam that pushes on tissues like sonic fingers and a tracking beam that monitors the resulting tissue motion. The researchers earlier showed ARFI to be an effective method for imaging the breast and liver.