Understanding MRI Scans
Magnetic resonance imaging (MRI) is a medical imaging technique that uses strong magnetic fields and radio waves to create detailed cross-sectional and 3D images of internal body structures. As the patient lies inside the MRI scanner, the magnetic fields temporarily realign water molecules in the body while radio waves create a signal that is detected by the machine.
MRI Scanner Components
The main components of an MRI scanner include:
- A powerful main magnet that generates a strong magnetic field
- Gradient coils that produce smaller magnetic fields
- A radio wave antenna to send signals
- A computer that processes the signals and constructs images
Some machines resemble a large donut or tunnel that the patient passes through while lying down on a motorized exam table. An MRI technologist will operate the scanner from a nearby computer.
Coping With a Cold Sensation in the Head
One of the most common sensations patients report during an MRI scan is feeling unusually cold in the head or face region. This is caused by circulation of coolant fluids that are used to control the temperature of the scanner's hardware components.
Why It Happens
Powerful superconducting electromagnets positioned all around your skull generate very strong magnetic fields inside the MRI machine. This causes them to heat up significantly. Liquid helium or nitrogen coolant systems allow the magnets to function properly at extremely cold temperatures.
As you slide into the center of the donut-shaped magnet bore on the exam table, your face and head end up very close to these cold magnet surfaces. The radical temperature differential is what leads to you perceiving an uncomfortable icy sensation unlike elsewhere in your warmer body.
Lasting Duration
The cold feeling in the head and face region only lasts during the actual image acquisition portion of the scan which is around 30-60 minutes depending on what body part is being examined. It is temporary and subsides once you exit from the machine bore after your scanning session completes.
Managing Discomfort
While the cold can be unpleasant, it causes no harm or health risks. However, some tips can make it more bearable so you can lie still:
- Wear a hat or headscarf to provide a warm barrier
- Use a blanket or ask for one
- Listen to provided music which diverts attention
- Close your eyes and relax breathing slowly
If it becomes truly intolerable, using the squeezeball and speaking through the intercom to halt the scan briefly may help. Communicate any severe reactions to the technician.
Why Staying Still is Vital During MRI
Aside from physical discomfort, maintaining near-perfect stillness is one of the biggest challenges for patients undergoing MRI scans. But why is motionless positioning so crucial for generating optimal images?
Susceptibility to Movement
MRI scanners capture very fine differences between structures and tissues throughout the body. Complex computational reconstruction transforms the radio wave signals into hands-off medical imaging without exposure hazards of traditional scans.
But this process relies on precision down to fractions of a millimeter in resolution. Even subtle motions like breathing, swallowing or twitching a foot can introduce distortions in the digital rendering algorithms.
Artifact Interference Patterns
When movement occurs during the pulse sequencing phase which lasts seconds to minutes, it shows up on images as wavy lines or blotchy shades rather than clean tissue demarcation. These unwanted artifacts make it far harder for radiologists to accurately interpret the scan when hunting for tumors, tears or other pathology.
Prolonging Scan Duration
Excessive motion usually requires re-scanning affected sequences to obtain usable information. This means more time spent subjected to the claustrophobic machine noise and cold sensations. Stillness helps get you out faster by capturing pristine images efficiently.
Trust that the technologist is monitoring you closely through cameras andmicrophone links. They will provide explicit breathing instructions for sequences sensitive to respiratory distortions in the abdomen or chest. Just heed directions communicated over the speaker.
What Happens If You Move Too Much?
Ideally with cooperation and communication, MRI scans proceed free of motion artifacts. But sometimes patients simply cannot tolerate the experience despite best efforts to remain still and calm.
Halting the Scan
If movements become too severe, the MRI technologist will stop the scan and pull you out from the machine bore. This could be due to visibility of major motion artifacts or concern for patient comfort and anxiety levels.
Offering Sedation
For select cases involving claustrophobia, injury limitations on positioning, or children unable to stay still, sedative medications may be clinically warranted so imaging can be successfully completed.
Your physician can prescribe a mild oral sedative like Valium to take beforehand or order monitored anesthesia care with an IV injectable drug to induce temporary sleep.
Trying Again Later
If sedatives are declined or still inadequate in resolving motion problems, the MRI may need to be rescheduled. Technologists will make notes about scan quality issues and workaround suggestions to inform future attempts.
Getting images necessary for medical decision making regarding conditions like back pain or concussion symptoms is the priority. Your care team wants to ensure diagnoses are accurate with the most optimal scan results possible.
Conclusion
The cold sensation in the facial region is a common harmless but unpleasant phenomenon many patients endure during MRI exams. Combined with the confining space and loud noises, it can certainly provoke anxiety and the urge to move for warmth and comfort.
Yet with focused breathing, trusted assurance from staff, and embracing mental escape tactics, most people can get through scans successfully. Being well-informed about what to expect in advance helps ease the process so crucial imaging for informing medical care can be achieved.
FAQs
Why does my head feel so cold during an MRI?
The powerful electromagnets in the MRI scanner circling your head give off substantial heat and require liquid cooling to function properly. This causes a radical temperature difference from the climate-controlled room, making your face feel unusually cold.
How long does the cold feeling last?
The icy sensation in the head region only persists while you are inside the actual donut-shaped tube of the MRI magnets during image acquisition. It subsides after the scan completes when you exit from the bore of the machine.
Will sneezing or swallowing affect my MRI scan?
It's best to minimize all motion during MRI sequences, but normal bodily functions like sneezes or swallows between image captures typically won't ruin the results. Just heed instructions from the technologist guiding you when to stay very still.
Can the MRI staff do anything about the cold?
Not directly or easily since adjusting the magnet cooling systems could impact image quality. Some facilities may have cloth hats or blankets to help make it more bearable. Mostly it requires mental patience knowing the chilling is temporary and harmless.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.
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