Reduction of MRI acoustic noise achieved by manipulation of scan parameters – A study using veterinary MR sequences

Sound pressure levels were measured within an MR scan room for a range of sequences employed in veterinary brain scanning, using a test phantom in an extremity coil. Variation of TR and TE, and use of a quieter gradient mode (‘whisper’ mode) were evaluated to determine their effect on sound pressure levels (SPLs). Use of a human head coil and a human brain sequence was also evaluated. Significant differences in SPL were achieved for T2, T1, T2* gradient echo and VIBE sequences by varying TR or TE, or by selecting the ‘whisper’ gradient mode. An appreciable reduction was achieved for the FLAIR sequence. Noise levels were not affected when a head coil was used in place of an extremity coil. Due to sequence parameters employed, veterinary patients and anaesthetists may be exposed to higher sound levels than those experienced in human MR examinations. The techniques described are particularly valuable in small animal MR scanning where ear protection is not routinely provided for the patient.