Magnetic resonance imaging-related programmable ventriculoperitoneal shunt valve setting changes occur often.

Abstract

Patients with programmable ventriculoperitoneal (VP) shunt valves undergo multiple skull radiographs to evaluate for setting changes resulting from MRI. Our purpose was to determine the rates of inadvertent, MRI-related, programmable VP shunt valve setting changes. In this retrospective cohort with a study period of January 2015-December 2018, we reviewed the pre- and post-MRI skull radiographs of patients with programmable VP shunts and collected the following data: Demographics, commercial type of the valve used, magnetic field strength of the MRI device used, and whether a setting change occurred. We used the chi-square test to identify variables associated with valve setting change. We identified 210 MRI exposure events in 156 patients, and an MRI-related valve setting change rate of 56.7%. The setting change rate was significantly higher with higher magnetic field strength (p = 0.03), and with Medtronic Strata™ valves compared to Codman Hakim™ valves (p < 0.0001). Inadvertent, MRI-related shunt valve setting changes are frequent with valves that lack a locking mechanism. Therefore, we suggest that when feasible, the clinicians could opt to manually reprogram the valves after the MRI to the preferred setting without the need for pre- and post-MRI radiographs. We believe that this protocol modification could help reduce ionizing radiation exposure and cost. Manufacturers may consider incorporating locking mechanisms into the design of such devices in order to reduce the unintended setting change rates.