How are radiological examinations like CT or MRT of moving organs (i.e. heart) carried out?

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How are radiological examinations like CT or MRT of moving organs (i.e. heart) carried out?

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Anonymous 0 Comments

CT scans don’t use radio waves. They use x-ray. For a ct scan of your heart, it takes pictures of you with x-rays. Like a normal camera, light bounces off the object and onto the camera sensor. Same with the x-ray. X-ray is radiated onto your chest and bounced back to a sensor. However, x-ray cam pass through human tissue, so they inject you with some due that can make x-Ray bounce back to the sensor. This dye is made primarily of iodine iirc. Like a photo, if you move too much, the picture is blurry. So for the heart scan not to be blurry, a drug is taken called a bets blocker which slows down your heart temporarily, and each wave of x-ray is radiated at each diastole, or when the heart rests or gets smaller.

For MRI, radio waves made by magnets are radiated to your heart. Your heart is made up of lots of atoms and the protons in that atom will dance when a certain frequency of radio waves hit them. They dance to get rid of energy and that released energy is released as waves as well and detected my the machine. All of this happens at the speed of light so a little heart movement won’t matter.

Anonymous 0 Comments

This is a long-standing problem with radiology.

For lungs, you simply ask the patient to hold their breath for 10 seconds or so. This usually accomplishes the task of fixating the lungs.

For the heart, you hook up some electrodes to the patient which measures the rhythm of the heart. Then you synch those electrodes to the CT/MRI. So the machine knows where the heart is in time, and then when you reconstruct the image, you pick only the images taken at the same phase of the rhythm.