Dutch medical technology company Philips announced on Thursday that it is recalling a particular series of magnetic resonance tomograph (MRT) devices following a warning issued by the Food and Drug Administration (FDA) in the United States. Excess pressure in the helium used in the device could lead to an explosion, the FDA reported earlier. The agency rated the recall as a “Class 1” case, the highest level. There are currently 340 of these systems in operation, 150 of them in the US. The recall represents a further blow to Philips in the US, where for the past more than two years it has had p…