title: Evaluation of epidural and peripheral nerve catheter heating during magnetic resonance imaging.
abstract: BACKGROUND
  Many epidural and peripheral nerve catheters contain conducting wire that could heat during magnetic resonance imaging (MRI), requiring removal for scanning.
  
  
  METHODS
  We tested 2 each of 6 brands of regional analgesia catheters (from Arrow International [Reading, Pennsylvania], B. Braun Medical Inc [Bethlehem, Pennsylvania], and Smiths Medical/Portex [Keene, New Hampshire]) for exposure to clinical 1.5- and 3-T MRI. Catheters testing as nonmagnetic were placed in an epidural configuration in a standard human torso-sized phantom, and an MRI pulse sequence applied at the maximum scanner-allowed radiofrequency specific absorption rate (SAR) for 15 minutes. Temperature and SAR exposure were sampled during MRI using multiple fiberoptic temperature sensors.
  
  
  RESULTS
  Two catheters (the Arrow StimuCath Peripheral Nerve and B. Braun Medical Perifix FX Epidural) were found to be magnetic and not tested further. At 3 T, exposure of the remaining 3 epidural and 1 peripheral nerve catheter to the scanner's maximum RF exposure elicited anomalous heating of 4°C to 7°C in 2 Arrow Epidural (MultiPort and Flex-Tip Plus) catheters at the entry points. Temperature increases for the other catheters at 3 T, and all catheters at 1.5 T were 1.4°C or less. When normalized to the body-average US Food and Drug Administration guideline SAR of 4 W/kg, maximum projected temperature increases were 0.1°C to 2.5°C at 1.5 T and 0.7°C to 2.7°C at 3 T, except for the Arrow MultiPort Flex-Tip Plus catheter at 3 T whose increase was 14°C.
  
  
  CONCLUSIONS
  Most but not all catheters can be left in place during 1.5-T MRI scans. Heating of less than 3°C during MRI for most catheters is not expected to be injurious. While heating was lower at 1.5 T versus 3 T, performance differences between products underscore the need for safety testing before performing MRI.
authors.affiliation: From the *Department of Anesthesiology and Critical Care Medicine and †Division of MR Research, Russell H. Morgan Department of Radiology and Radiologic Science, The Johns Hopkins University and School of Medicine, Baltimore, Maryland.
authors.forename: Sean
authors.initials: S
authors.lastname: Owens
authors.forename: M Arcan
authors.initials: MA
authors.lastname: Erturk
authors.forename: Jean-Pierre P
authors.initials: JP
authors.lastname: Ouanes
authors.forename: Jamie D
authors.initials: JD
authors.lastname: Murphy
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Wu
authors.forename: Paul A
authors.initials: PA
authors.lastname: Bottomley
mesh_terms: D002404:Catheterization / Q000295:instrumentation* / Q000379:methods; D002408:Catheters, Indwelling; D004824:Epidural Space; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000295:instrumentation; D008422:Materials Testing; D010525:Peripheral Nerves; D019047:Phantoms, Imaging; D013696:Temperature; D013997:Time Factors