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, B. Braun Medical, and Smiths Medical/Portex) for exposure to clinical 1.5 and 3 Tesla (T) MRI. Catheters testing as non-magnetic were placed in an epidural configuration in a standard human torso-sized phantom, and an MRI pulse sequence applied at the maximum scanner-allowed radio frequency (RF) specific absorption rate (SAR) for 15 minutes Temperature and SAR exposure were sampled during MRI using multiple fiber-optic temperature sensors. Results Two catheters (the Arrow StimuCath Peripheral Nerve, and Braun Medical Perifix FX Epidural) were found to be magnetic and not tested further. At 3T, exposure of the remaining 3 epidural and 1 peripheral nerve catheter to the scanner’s maximum RF exposure, elicited anomalous heating of 4 to 7°C in 2 Arrow Epidural (MultiPort and Flex-Tip Plus) catheters at the entry points. Temperature increases for the other catheters at 3T and all catheters at 1.5T were ≤1.4°C. When normalized to the body-average FDA guideline SAR of 4W/kg, maximum projected temperature increases were 0.1 to 2.5°C at 1.5T and 0.7 to 2.7°C at 3T, except for the Arrow MultiPort Flex-Tip Plus catheter at 3T whose increase was 14°C. Conclusions Most but not all catheters can be left in place during 1.5T MRI scans. Heating of <3°C during MRI for most catheters is not expected to be injurious. While heating was lower at 1.5T vs 3T, performance differences between products underscore the need for safety testing before performing MRI.

MRI safety and devices: An update and expert consensus

“…In 2002, Shellock reported that an epidural catheter manufactured with 604V stainless steel (Arrow International, Walpole, MA) showed limited deflection and rotation at 3T, but communication with Arrow indicates no catheters are currently manufactured using stainless steel. In the only other study found, Owens et al did not adhere to the strict testing standards published by ASTM International, and ISO/TS 10974 was not published at the time. Instead, the methodology focused on compliance with the FDA's RF and SAR guidelines under in vitro settings.…”

Comparison of effectiveness of epidural analgesia and monitored anesthesia care for high-intensity focused ultrasound treatment of adenomyosis

“…Another point to be addressed in continuous EA with catheter insertion and MRI scan is the iatrogenic risk associated with MRI compatibility of the catheters [37]. In contrast to classical catheters made of nylon, which were used in this study, or polyether block amide, a number of new catheters are magnetic with coil-reinforcement, which can lead to significant catheter displacement under the magnetic field of an MRI scanner.…”

“…In contrast to classical catheters made of nylon, which were used in this study, or polyether block amide, a number of new catheters are magnetic with coil-reinforcement, which can lead to significant catheter displacement under the magnetic field of an MRI scanner. Furthermore, even if a few coil-reinforced catheters are not associated with magnetic displacement, hazardous temperature increases at the entry point may occur under a 3-T magnetic field [37]. This would cause a cutaneous burn at the catheter entry site and/or along the subcutaneous tunneling track.…”

Surgical Management of the Retained Epidural Catheter Fragment Complicated by Postoperative Phlegmon

“…CT has been recommended to locate retained catheters due to high resolution and ease of obtaining the test [7,8]. Magnetic resonance imaging (MRI) of the spine is not recommended as first diagnostic test of choice for ferromagnetic catheters due to metallic artifact, larger slice size, risk of neural injury secondary to heating of a wire-enforced catheter in the epidural space, and risk of catheter movement [9][10][11]. [1,3,7,18,19,20,21].…”