Answering The Most Common Questions About Maintaining Your MRI Cold Head

Your MRI is an expensive piece of equipment vital to your hospital’s ability to accurately diagnose its patients. Because of how expensive it is, it’s important to use it and maintain it properly to avoid the need for repair or replacement. The reason that MRIs are so expensive–and that the cost of repairing or replacing faulty parts is so expensive–is because the MRI is made up of many complex components, including the cold head. The cold head is arguably one of the most important parts of an MRI. Without a properly functioning cold head, the MRI itself will not be able to function.

What is an MRI Cold Head?

MRIs use superconducting magnets to generate a magnetic field powerful enough to capture the detailed diagnostic images you need. These magnets must be kept cold to retain their superconductivity. To do this, liquid helium is used. However, the intense heat of the superconducting magnets causes the liquid helium to turn into gas. The cold head is a component located inside of the MRI’s cooling system that re-condenses the helium gas back into liquid, thereby helping to prevent it from boiling off completely.

Without the cold head. the liquid helium would burn off way too fast, requiring you to constantly refill the helium supply, which is incredibly costly. Without liquid helium, the MRI’s magnet will lose its superconductivity and quench, which is a potentially dangerous process in which the entire system shuts down.

What Can Cause a Cold Head to Fail? Common Issues

If your cold head fails, your MRI system will run out of liquid helium, thereby losing its superconductivity. Essentially, it will be rendered unusable until you can get your cold head fixed or replaced. Besides the fact that repairs or replacement can be costly, the amount of downtime your system might experience can be costly as well.

Knowing what can cause a cold head to fail can help you better prepare for potential downtime as well as take steps to prevent damage from occurring in the first place. The following are some of the common issues that can cause a cold head to fail:

Wear and Tear

The cold head is continuously working hard to help protect your MRI from overheating, which means you can expect it to experience wear and tear over time as a result of normal use. A cold head’s performance is tracked is by its re-condensing margin, and regular wear and tear will gradually reduce its re-condensing margin over the years. In fact, cold heads tend to lose around ten percent of their cooling capacity every year. Once the re-condensing margin reaches close to zero, it will need to be replaced. Regular maintenance can help reduce the amount of wear and tear the cold head experiences and help to prolong its lifespan.

Contamination

If the helium inside of your cold head becomes contaminated with any impurities, it can reduce its efficiency or even cause damage to the cold head itself. There are several ways your cold head could become contaminated, like the oil from inside of your MRI’s compressor finding its way into your cold head. Generally, contamination occurs gradually, but it can end up causing serious problems if it’s not dealt with right away.

Helium Loss or Fluctuation

If the cold head’s re-condensing margin is dropping sharply or fluctuating (and it’s not an issue with your compressor), it means your cold head is not functioning properly to maintain the proper levels of liquid helium. If the problem isn’t identified quickly, it could result in the need to replace a significant amount of helium. If it’s not identified at all, it could cause your MRI to quench due to the lack of necessary helium.

Maintenance is Key

Regular maintenance is essential to ensure that your cold head is functioning properly. During routine maintenance, the cold head will be inspected for potential contamination through air and oil tests. The cold head’s adsorber should be replaced once a year to help reduce the risk of contamination.  

The cold head’s re-condensing margin will be also be evaluated during maintenance, and if it’s low, the cold head should be replaced to prevent your MRIs helium from burning off at an ascending rate, which can lead to quenching.

Choosing a Service Contract

The cold head may be covered as part of your OEM (original equipment manufacturer) service or through a third-party service contract. When shopping around for a service contract, there are certain things to look for. Besides the basic service rates (which are typically charged in monthly or yearly fee payment plans), find out how much is charged for adsorber and cold head replacement, whether the contract covers all parts and labor, whether the parts are OEM quality (if you’re going through a third-party), and how often preventative maintenance inspections are scheduled and what it entails (look for preventative maintenance that includes thorough contamination testing).

Replacing a Cold Head

Maintenance will help to prolong the life of your cold head; however, you will need to have it replaced eventually. Most cold heads will cost between $5,000 and $10,000 to replace, but this is a minor investment compared to how much it could cost should your cold head fail and cause severe damage to your entire MRI system.

When to replace your cold head depends on how well you’ve maintained it and whether it was purchased new or refurbished. A refurbished cold head will last between three and four years, while a new cold head could last upwards of five years. The age and condition of the MRI system itself can also impact how often you’ll need to replace your cold head. If it needs to work harder than usual due to the age of the MRI system, the cold head may not last as long as usual.

Steps You Can Take Today

If you haven’t been concerning yourself with your MRI’s cold head, it’s time to start taking steps to prevent potential damage and to prolong the life of your cold head for as long as possible. First check your service contract to find out what’s covered in regards to cold head maintenance. If it doesn’t include preventative cold head maintenance, you’ll want to find a service contract that does. You should also go over the past maintenance of your cold head. If it hasn’t been serviced, you may want to schedule an inspection to evaluate its condition.

One step you can take on your own is checking the re-condensing margin. Your MRI’s console should provide the metrics for your cold head’s re-condensing margin. If it’s low,  you will need to replace your cold head soon.