How Do MRIs Work?

Posted on: 07/21/2015

You go into a tube, the machine whirs, and a little while later—voila!—there’s an image that shows what’s going on inside your body. At least, that’s the way it seems for most of us. Whether you’re due for an MRI scan or simply curious for future reference, knowing a little more about how MRIs work is a great way to start the process.

MRI stands for Magnetic Resonance Imaging, which means it’s a machine that uses magnetic fields and radio waves to create images of the body that one couldn’t otherwise see. Using the images created from MRIs helps hospitals to diagnose diseases, determine how severe certain injuries are, investigate general bodily issues, and more.

The Process

The study begins with the patient, typically in a gown of some sort, being positioned in the MRI scanner. MRI scanners come in a variety of different models, with each providing a different set of benefits. Most MRI machines look like a big tube with a table in the center where the patient lays.

When the patient is situated, the MRI creates a strong magnetic field around them. This magnetic field is very powerful, so patients will have to remove accessories like jewelry, credit cards, and other metallic objects before entering the room. While this maintains the image quality of the scan, ensuring a crisp picture, it also ensures the safety of the patient.

What happens next is very complex. To understand it fully, one would need a deep understanding of science and medicine. Here’s what happens in a nutshell: inside the MRI machine are wire loops. To create the magnetic field, an electric current is run through them. As the magnetic field is created, the machine is also sending and receiving radio waves through a coil placed where the scan needs to be focused.

Inside your body are small particles called protons. When the magnetic field is created, the protons all line up in the same direction, much like a needle of a compass might point to a nearby magnet. The strategically placed coil then starts emitting radio waves, knocking the protons out of alignment. As they realign, they send energy signals that the coil picks up. This information is then sent to a computer, processed, and turned into an image.

According to Medical News Today, unlike CT scanning or x-rays, MRIs do not cause ionizing radiation. MRI exams are also completely painless and noninvasive, typically only taking 30 to 45 minutes.

Seattle Diagnostic Imaging Services

Via Radiology provides radiology and diagnostic imaging procedures including bone density tests, mammograms, ultrasound exams, MRI exams, CT scans and other imaging modalities. Contact us online for more information.

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