Sperling Prostate Center

Learning About MRI the Fun Way

UPDATE: 2/3/2022
Originally published 1/22/2015

The serendipitous discovery of the website “How Things Work” developed by Dr. Prasanna Tilakaratna has been a source of delight on the few occasions I’ve visited it. Pras, as he prefers to be called, is a unique humanistic blend of science, philosophy, and a positive outlook that makes his sites enjoyable.

I thought it was worth revisiting his simple, illustrated explanation of how MRI works to see how he may have updated it while still sprinkling it with gently humorous comments. He makes demystifying MRI for laypersons an art. As he points out, “If you are an imaging professional, I am sorry to say that my explanations will be too basic for you, and I would advise you to read much more detailed material elsewhere (Good Luck!).” Indeed, grasping complex physics/math formulas, and grappling with quantum mechanics to decode subatomic particles takes more than just good luck, as I have experienced in my own research with MRI and Artificial Intelligence.

In any case, it was fun to explore Pras’ website in 2015, and it’s even more fun today. For example, check out his Magic Breathing Wheel. How does he do that???

If you find his MRI explanation a bit too simplistic or time-consuming as you proceed through his slides, you might turn to the National Institute of Biomedical Imaging and Bioengineering. Along with its very good explanation of MRI physics and medical applications, the site addresses possible risks. Of course, MRI is incredibly safe—definitely safer than CT and x-rays since there’s no exposure to radiation. But the site wisely identifies the following considerations:

  • The magnetic field can interact with implants containing certain metals (always tell your doctor about any implants before undergoing MRI)
  • Loud noises that require ear protection
  • Possible twitching sensations due to rapidly switching magnetic fields
  • Patients with certain kidney problems may not be able to have gadolinium-based contrast agents
  • Claustrophobia may be a problem for some patients (always tell your doctor)
  • Pregnancy may be a contraindication, especially in the first trimester—though no harm has been demonstrated, it’s good to err to the side of caution.

Life can get busy, but I hope you’ll take a little time to let Prasanna Tilakaratna enlighten you on MRI.


By accident, I discovered a web presentation on the basic principles of MRI that was not only easy and clear, but also entertaining and charming. Sound impossible? It’s not as far-fetched as it seems, thanks to the work of Prasanna Tilakaratna, a very intelligent man with a gentle sense of humor.

Pras, as he likes to be called, is a consultant anesthesiologist at a community hospital about 30 miles east of London. I never met him, of course, but his “About Me” page makes it very easy for you to get to know him. His “How Equipment Works” website is completely voluntary and extremely gratifying. He writes, “While I do spend a huge amount of personal time on this website, I get great joy feeling that I might be helping someone somewhere understand the physical principles behind equipment.”

The term Magnetic Resonance Imaging gives a big clue that the principles might be difficult to grasp. How many of us walk around with a working knowledge of magnetism, radio frequency, and subatomic particles (hydrogen protons)? He not only explains the principles, but he also describes the device in a way that demystifies it. If you’ve ever had an MRI, did you know that the coils that produce the magnetic field are housed in liquid helium at -450° Fahrenheit? Do you know why they have to be kept so cold? Do you know why the imaging process is so noisy? If you’re already starting to get a headache just thinking about it, Pras and his illustrations take you step by step into how magnetic resonance is harmlessly converted into detailed, accurate images of internal structures based on the water in your body. Along the way, he intersperses joking observations that add a bit of comedy.

If you have about 15 minutes to indulge in painless learning, I invite you step into my world of magnetic resonance imaging. Pras not only makes it understandable, but adds a sense of wonder over one of the truly miraculous ways technology helps medical practice. Visit http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html and have fun!

About Dr. Dan Sperling

Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Prostate Center.

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