Cryogenics in MRIs: Why It Matters

By: Hose Master | On: October 23, 2024
Close-up of MRI scanner in examination room at the hospital.

 

Medical imaging, among many other modern technologies, has revolutionized healthcare. One imaging method that has played a pivotal role in this field is magnetic resonance imaging, or MRI, particularly for detecting issues like strokes and tumors. MRIs are machines that use magnetic fields to generate extremely detailed images of inside the body, often the brain and spinal cord. They are distinct from other imaging techniques because they do not use radiation. As the population ages and more people live past their 70s, there’s a growing demand for diagnostic imaging. So, we’re quite reliant on MRIs with over 50,000 units installed globally and over 95 million scans performed annually. While they are certainly tremendously beneficial for patients, they can be extremely costly to both operate and repair. It’s only with the integration of quality cryogenic components that MRIs can function properly and efficiently.

There are a few key components of MRI machines that are responsible for creating the images that healthcare professionals need for their patients: the magnet, the gradient coils, and the radio frequency coils. These highly delicate parts are what generate the magnetic field and transmit signals, producing MRI images.

While the machine is being used, the magnet and coils get very hot. The magnet within an MRI machine is what’s called a superconductor: a type of material that can conduct electricity with no energy loss. However, preventing energy loss is only possible if the superconductor is kept cold. So, when these magnets get hot, their superconductor capabilities are diminished, and proper images cannot be created. The rising temperature in the magnet is what’s known as quench. Quench can cause irreparable damage to the magnet, which is the most expensive part of an MRI machine. So, preventing quench and ensuring these key components are kept cool is crucial. This is where cryogenics comes into play.

 

The Cooling System

Most MRIs use a liquid helium cooling system because helium has a boiling point of around -450 degrees Fahrenheit, making it an excellent cryogen. Unfortunately, there’s a dire shortage of helium, making it very expensive (around $30-50 per liter), and these systems typically require well over a thousand liters of helium to operate. Therefore, helium costs can increase quickly, especially if leaks are present in the system.

Diagram of different components of an MRI machine

(Figure 1.1 - ResearchGate)

Luckily, with modern technology, helium isn’t boiled off by the hot magnet and lost forever in the cooling process. The cold head (shown in red in Figure 1.1) is a part of the cooling system that recondenses helium that’s boiled by the magnet. This essentially recycles the helium in a closed cycle, in which the helium is repeatedly boiled and recondensed. This process requires the usage of very precise, high-quality helium coolers, containers, and transfer lines. Otherwise, the whole system is at risk of malfunctioning.

 

Cooling System Malfunctions

One of the most common issues with MRI machines is a cooling system failure. This oftentimes presents itself as low helium levels, which could be the result of a leak or because the compressor has stopped working. Another issue is high amounts of vibration which can hurt the functionality of the cryocooler, affecting image quality. Leaks and movement are, therefore, two of the prime concerns with MRI cooling systems. Because helium is being stored and transferred at cryogenic temperatures, specifically designed transfer lines are integral to this cooling system. While non-metallic hoses cannot handle cryogenic temperatures, corrugated metal hoses tailored for this specific application are ideally suited to tolerate sub-zero temperatures and high degrees of movement.

Corrugated metal hoses intended for cryogenic applications must be designed with superior flexibility and resistance to media permeation in mind. This is why a gentle forming process is crucial to maximizing the service life of the hose. Hose Master manufactures corrugated metal hoses utilizing Stress-Lite™ forming, which ensures a uniform wall thickness, minimizes torsional stress, and allows for a high degree of flexibility. A robust braid covering provides high-pressure performance and offers protection to the hose, saving money on maintenance costs in the long run. Hose Master’s corrugated metal hoses provide the superior flexibility, temperature capabilities, and resistance to pressure and vibration that are precisely needed for secure and efficient MRI operation.

The integration of cryogenics with MRI technology has unquestionably transformed medical imaging. And with the growing demand for MRI scans, our medical needs depend heavily on the safe and productive operation of these devices. With helium being a finite resource that plays a pivotal role in maintaining the longevity of MRIs, conservation is a priority. Protecting the helium protects the machine, which protects the patient, thereby protecting the facility’s investment. With Hose Master, every box is checked. As this technology continues to evolve, efficient cooling will continue to be a critical factor in the MRI market.

 

(Learn more about other applications of Hose Master’s corrugated metal hoses here)

 

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