Short‐term effects experienced during examinations in an actively shielded 7 T MR

Abstract

The objective of this study was to evaluate occurrence and strength of short‐term effects experienced by study participants in an actively shielded (AS) 7 tesla (7 T) magnetic resonance (MR) scanner, to compare results with earlier reports on passively shielded (PS) 7 T MR scanners, and to outline possible healthcare strategies to improve patient compliance. Study participants (n = 124) completed a web‐based questionnaire directly after being examined in an AS 7 T MR (n = 154 examinations). Most frequently experienced short‐term effects were dizziness (84%) and inconsistent movement (70%), especially while moving into or out of the magnet. Peripheral nerve stimulation (PNS)—twitching—was experienced in 67% of research examinations and showed a dependence between strength of twitches and recorded predicted PNS values. Of the participants, 74% experienced noise levels as acceptable and the majority experienced body and room temperature as comfortable. Of the study participants, 95% felt well‐informed and felt they had had good contact with the staff before the examination. Willingness to undergo a future 7 T examination was high (>90%). Our study concludes short‐term effects are often experienced during examinations in an AS 7 T MR, leaving room for improvement in nursing care strategies to increase patient compliance. Bioelectromagnetics. 2019;9999:XX–XX. © 2019 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.

Subjectively Reported Effects Experienced in an Actively Shielded 7T MRI: A Large‐Scale Study

“…The study was approved by the appropriate Ethics Committee (entry nos. 2015/434 and 2016/126) and informed written consent was obtained from all subjects, as described by Hansson et al…”

“…This study did not make use of examinations included in a previous study and the questionnaire was updated with additional questions regarding experience and anxiety, and by exclusion of the visual analog scale (VAS) in favor of a six‐point Likert scale and a seven‐point adjectival scale . Before the examination, all of the subjects underwent a strict MRI safety check, changed from their street clothes to hospital pants and gown, and were provided with hearing protection as in a previous study .…”

“…This study did not make use of examinations included in a previous study and the questionnaire was updated with additional questions regarding experience and anxiety, and by exclusion of the visual analog scale (VAS) in favor of a six‐point Likert scale and a seven‐point adjectival scale . Before the examination, all of the subjects underwent a strict MRI safety check, changed from their street clothes to hospital pants and gown, and were provided with hearing protection as in a previous study . After the examination, a web‐based questionnaire (REDCap; research electronic data capture; http://project-redcap.org/) was used to collect data on demographics (gender (M/F), age (y), self‐estimated sensitivity regarding motion sickness (kinetosis), on any short‐term effects, and on body and room temperature experienced, scanner noise, the communication system, and willingness regarding any future 7T MRI examination.…”

“…The operator entered the information on session parameters including the length of the examination (min), the part of the body that was examined, and the orientation of the body in the field (head‐first or feet‐first). Experience of the short‐term effects dizziness, inconsistent movement, nausea, headache, and metallic taste were evaluated for four situations: lying on the table and moving into the scanner (in), being at the isocenter (inside), moving out of the scanner (out), and having gone outside the scanner room after the examination (outside), in accordance with a previous study . These short‐term effects, together with light flashes, self‐estimated sensitivity regarding motion sickness, and PNS were evaluated regarding quantity and/or intensity using a six‐point Likert scale: none, very little, little, moderate, much, and very much .…”

“…Previous publications have shown that short‐term effects—dizziness/vertigo, inconsistent movement, nausea, headache, and a metallic taste—may be experienced by subjects in the 7T environment, but fewer sensations have been reported in the 1.5T environment, and with considerably (mean 84%) lower mean scores . Evaluation often needs to rely on self‐reporting of these effects, which further are often highly subjective, although in general are physiological and may, by some individuals, even be experienced in mock scanners with no static magnetic field, radiofrequency field, or gradient field .…”