Philips is recalling hundreds of MRI machines around the globe over concerns the medical imaging equipment could explode during normal operation - something a US Food and Drug Administration (FDA) bulletin states has already happened once before.

The "class one" recall - the most serious type - was published by the FDA online this week, and warns owners of Philips Panorama 1.0T HFO magnetic resonance imagers to discontinue use of the machines until a service technician is able to make corrective repairs.

Sold between 2001 and 2016, the machines are employed broadly by medical facilities around the world to image the inside of patients' bodies. Today, 150 Panorama 1.0T HFO machines are operating in the United States, and there are reportedly 340 globally.

The recall was issued after it was determined that during a "quench" - when the magnet coils are no longer at near-absolute zero and lose their superconductivity - the helium gas that's supposed to super-cool the coils evaporates and could cause the device to rupture.

Ordinarily this gas would be vented out, but if that's blocked, the equipment may go pop. This, the bulletin notes, could result in property damage and/or serious injury from chemical exposure, lack of oxygen, tissue damage, and mechanical trauma.

"During a quench, which is not common, a large amount of helium evaporates and is vented outside the building through a venting system," the recall explains. "If an unknown blockage is present in the venting system and the pressure exceeds design limits, the structural integrity of the system could be compromised."

While a quench may not be common, and it isn't terribly desirable, it can occur during normal operation if things go awry, or be triggered manually in extreme circumstances by an operator pressing the magnet emergency stop button.

According to the FDA filing, there has been one reported event in 22 years of a quench operation causing an explosion. Thankfully no one was injured in that case.

Philips says it's notified all affected customers of the recall, and that all US users will be visited by a field service engineer to inspect the system and perform corrective replacement or repairs, if necessary. We're left to speculate what those changes entail. Customers outside the US should contact Philips within 30 days of the notice.

The recall represents yet another black mark for Philips which is still grappling with the consequences of a previous recall and subsequent class action suits related to its Respironics devices.

Issued in June 2021, the maufacturer recalled several ventilators, BiPAP machines, and CPAP machines due to potential health risks linked to dissolving polyurethane foam which could break down and be inhaled by users. ®

https://www.theregister.com//2023/12/21/philips_exploding_mri/