Abstract
MR-generated acoustic noise can contribute to patient discomfort and potentially be harmful. One way to reduce this noise is by altering the gradient output and/or waveform using software optimization. Such modifications might influence image quality and switched gradient field exposure, and different techniques appear to affect sound pressure levels (SPLs) to various degrees. To evaluate SPLs, image quality, switched gradient field exposure, and participants' perceived noise levels during two different acoustic noise reduction (ANR) techniques, Quiet Suite (QS) and Whisper Mode (WM), and to compare them with conventional T2-weighted turbo spin echo (T2W TSE) of the lumbar spine. Prospective. Forty adults referred for lumbar MRI. Conventional T2W TSE, T2W TSE with QS, and T2W TSE with WM were acquired at 1.5T. Peak SPL (A-weighted decibels, dBA), perceived noise levels (Borg CR10®-scale), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), three radiologists' qualitative assessments in image quality on an ordinal scale 1-4, switched gradient field exposure (% general public), and gradient currents were measured. Interobserver reliability was reported as percentage agreement. Repeated measures ANOVA, Friedman's ANOVA, and Wilcoxon's Signed-Rank Test for acoustic noise measurements and image quality assessments. Mean peak SPLs were 89.9dBA, 74.3dBA, and 78.8dBA for conventional, QS, and WM, respectively (P < 0.05). Participants perceived QS as the quietest and conventional as the loudest sequence (P < 0.05). No qualitative differences in image quality were seen (P > 0.05), although QS showed significantly improved SNR and CNR (P < 0.05). Switched gradient field exposure was reduced by 66% and 48% for QS and WM, respectively. Without degrading image quality, both QS and WM are viable ANR techniques in lumbar T2W TSE. QS provided the lowest SPL, the lowest gradient field exposure and was perceived as the most silent among the three sequences. 1 TECHNICAL EFFICACY STAGE: 5.
Highlights
MR-generated acoustic noise can contribute to patient discomfort and potentially be harmful
This corresponded to an 84% reduction in sound pressure with Quiet Suite (QS)
When comparing QS with Whisper Mode (WM), we found that all contrast-to-noise ratio (CNR) values between cerebrospinal fluid (CSF) and adjacent tissues were significantly increased with QS (P < 0.05) and that signal-to-noise ratio (SNR) values were significantly improved at the level of conus medullaris (P < 0.05) and in CSF (P < 0.05)
Summary
MR-generated acoustic noise can contribute to patient discomfort and potentially be harmful. One way to reduce this noise is by altering the gradient output and/or waveform using software optimization Such modifications might influence image quality and switched gradient field exposure, and different techniques appear to affect sound pressure levels (SPLs) to various degrees. Purpose: To evaluate SPLs, image quality, switched gradient field exposure, and participants’ perceived noise levels during two different acoustic noise reduction (ANR) techniques, Quiet Suite (QS) and Whisper Mode (WM), and to compare them with conventional T2-weighted turbo spin echo (T2W TSE) of the lumbar spine. Assessment: Peak SPL (A-weighted decibels, dBA), perceived noise levels (Borg CR10®-scale), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), three radiologists’ qualitative assessments in image quality on an ordinal scale 1–4, switched gradient field exposure (% general public), and gradient currents were measured.
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