Understanding MRI Scanning: Safety and Potential Risks

MRI Scanning: The Paradox of Safety and Potential Hazards

Medical imaging technology has come a long way in recent decades, and Magnetic Resonance Imaging (MRI) is one of the most revolutionary advancements in the field. Despite the advanced technology, MRI scans are known for their high safety profile, with a vast array of benefits for patients. However, there are certain risks and considerations that must be taken into account to ensure a safe and successful scan.

Paradox of MRI Safety

One of the fascinating facets of MRI is its inherent safety compared to other imaging modalities. It is widely acknowledged as the only known medical imaging technique in which a person has been killed by the scanner, specifically due to causes attributable to the scanner. At the same time, MRI is considered one of the safest forms of medical imaging both in the short and long term.

This seeming paradox is rooted in the nature of MRI scans. An MRI scan itself is painless; the only discomfort often experienced is the feeling of claustrophobia due to the confined space of the MRI machine. The machine can become quite loud, but this can be easily mitigated with earplugs, and a mild sedative can be helpful in managing anxiety.

Understanding the MRI Machine

Under the hood, an MRI machine operates with a powerful static magnetic field - approximately 50,000 times stronger than the Earth's magnetic field for a 3 Tesla (T) scanner. This magnetic field can pose significant risks if metallic or non-MRI safe objects are brought into the scanning suite. The issue stems from the fact that the magnetic field is extremely strong, and any object with even a small amount of metallic content can be rapidly accelerated and become a dangerous projectile, potentially causing severe injury or death.

Non-compliance and Safety Risks

Most attention in the medical community is given to the risks posed by metal shrapnel or other metallic objects within the patient's body. However, the majority of accidents in MRI suites occur due to a lack of compliance with safety protocols by individuals who bring non-MRI safe equipment into the imaging area. The magnetic field's strength increases dramatically with distance, meaning that any metallic object attracted by the magnet will experience a force proportional to its mass and the acceleration caused by the field. This force can be dangerously high, especially when applied to the human body, a 'squishy' target.

Other Risks Associated with MRI Scanning

Among the other risks associated with MRI scanning, two distinct issues stand out:

Contrast Agent Reactions

Contrast agents are often used in MRI scans to provide better visualization of certain tissues and organs. While most patients tolerate these agents well, some individuals may experience adverse reactions, particularly those with compromised kidney function. To mitigate this risk, most competent scanning facilities will conduct an eGFR test to assess kidney function before the MRI. This ensures that the patient is safe to undergo the contrast-enhanced scan.

Tissue Heating

Fast Spin Echo (FSE) pulse sequences, characterized by high-frequency changes in the secondary magnetic field, can cause tissue heating. This heating is usually imperceptible, and it is exceedingly rare for a patient to be injured by this phenomenon. Nevertheless, MRI technicians are trained to minimize this risk and ensure that patients are as comfortable as possible during the procedure.

MRI Scanning: A Painless Experience

Despite the potential risks, an MRI scan is generally a painless and comfortable experience. Patients are positioned on a table, which is then moved into the MRI machine, where they remain still for the duration of the scan. The MRI machine is designed to be as comfortable as possible, with patients often cushioned with pillows. Additionally, some imaging centers offer music options that can be played through the machine, helping to ease any anxiety.

Preparation for an MRI Scan

To ensure a safe and comfortable scanning experience:

Patients should bring any relevant medical records and discuss any concerns with their healthcare provider. Patients with claustrophobia should inform their doctor beforehand, as they may be prescribed a mild sedative to help relax them. Patients should wear comfortable clothing and remove any metal accessories before the scan. Patients should get earplugs to combat the noise generated by the machine.

In summary, while MRI scanning poses certain risks, the safety measures in place ensure that the benefits far outweigh the potential hazards. By understanding and addressing these risks, patients can undergo MRI scans with confidence.