basics | magnetic resonance imaging

series: knowledge cards
May 10, 2019


— contents —

~ about
~ videos
~ special section
~ learning

image | above
An MRI diagnostic imaging machine installed in a hospital.

about | magnetic resonance imaging

MRI stands for magnetic resonance imaging. It’s a closet-size machine with powerful scanning ability, that can see inside human and animals bodies. It’s one of the most relied-upon medical tools for diagnosis and a common procedure around the world. MRI is especially good at imaging soft tissue.

At some point: you, your family, your friends, or your pet will likely have an MRI scan to check-up on health, diagnose an illness, or visualize an injury. MRI is safe and installed ubiquitously at hospitals + clinics — considered a gold standard of medical care. MRI is also a valuable research tool — for scientists making discoveries and designing medical therapies.

— basic background —

MRI uses a strong magnetic field and radio waves to create detailed images of the organs and tissues in the body. Since its invention, doctors and researchers continue to refine MRI techniques to assist in medical procedures and research. The development of MRI revolutionized medicine.

An MRI scan uses a large magnet, radio waves, and a computer to make a series of high-resolution, cross-sectional images of internal organs, tissues, and bones in the body. MRI scanning is a non-invasive and painless procedure. The cost of a basic MRI scanner starts at $150,000 but can exceed several million dollars.

The scanner usually resembles a large tube with a table in the middle, for the patient to slide in. Unlike CT scans and x-ray imaging, MRI doesn’t give off potentially harmful ionizing radiation. CT means computerized tomography, it’s a type of high-tech x-ray scanner. All three imaging techniques are common for diagnosis.

The development of the MRI scan was a huge milestone for the medical world. Doctors, scientists, and researchers can examine the inside of the human body in detail using a non-invasive tool. Here are some examples of how an MRI scanner can be used for diagnosis:

  • preventative medicine: whole body scan
  • preventative medicine: breast cancer screening
  • discovering: tumors, cysts, growths
  • detecting joint injuries
  • detecting skeletal injuries
  • evaluating the brain + spinal cord
  • evaluating heart abnormalities
  • evaluating abdominal organ abnormalities
  • evaluating female pelvic pain
  • evaluating female reproductive organs

— getting an MRI scan —

The use of MRI technology is always expanding in scope and use. There’s little preparation required to get an MRI scan. At the clinic, you might be asked to change into a gown. Since magnets are used, no metal items can be close to the scanner: such as jewelry, devices, or accessories that will interfere with the machine. Some patients can’t get an MRI scan if they have metal inside their body — such as: bullets, shrapnel, metallic foreign bodies. This can also include medical devices: such as cochlear implants, aneurysm clips, and pacemakers.

Patients will sometimes get an injection of intra-venous (IV) contrast liquid — a type of dye that stains specific types of tissues the doctor wants to see in detail. The contrast dye improves the visibility of a particular tissues under MRI scan. During the scan, it’s essential to stay still. Any movement will blur the images — like a camera trying to take a picture of a moving object. Depending on the images, at times you might need to hold your breath.

watch | video
How an MRI machine functions.

watch | video
Comparing MRI scan + CT scan.

special section | mechanics
from: Mouser Electronics

Several technologies exist for seeing the soft tissues and bone inside the human body — the oldest is x-ray. Today, 4 sophisticated technologies are evolving to improve precision + lower cost:

  • computed tomography — CT
  • positron emission tomography — PET
  • magnetic resonance imaging — MRI
  • ultra-sound — U/S

Each of these diagnostic machines sends a signal into the body — when the body reacts to the signal: the reaction will affect the original signal or a return signal. All of these techniques can discriminate small, important signals from a cacophony of jumbled noise.

So high-fidelity, low-noise electronic components and design are critical to extracting these tiny signals and sending them — as accurately as possible — for processing + display. So medical imaging is one of the most demanding, interesting, and rewarding fields in electronic design. We’ll look at the mechanical function of these 4 modern diagnostic imaging systems.

on the web | learning

Mouser Electronics | Look Inside — CT, PET, MRI, ultra-sound
deck: A mechanical overview of medical imaging machines.

on the web | learning

Philips | MRI innovations
Siemens | MRI innovations
GE Health Care | MRI Innovations
Aspect Imaging | MRI Innovations

Bay Imaging Consultants | What’s the difference between MRI scans + CT scans?

— notes —

CT = computerized tomography
MRI = magnetic resonance imaging
U/S = ultra-sound

Rx = prescription
Dx = diagnosis

GE = General Electric
* GE Health Care under umbrella of General Electric

[ story file ]

story title: basics | magnetic resonance imaging
deck: series: knowledge cards
year: 2019
section: digest

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