Hamaguchi Takashi, Miyati Tosiaki, Ohno Naoki, Matsushita Tatsuhiko, Takata Tadanori, Matsuura Yukihiro, Kobayashi Satoshi, Gabata Toshifumi
Radiology Division, 88335Kanazawa University Hospital, Kanazawa, Ishikawa, Japan.
Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, 12858Kanazawa University, Kanazawa, Ishikawa, Japan.
Acta Radiol. 2023 Mar;64(3):1212-1221. doi: 10.1177/02841851221100079. Epub 2022 May 11.
The acoustic noise in magnetic resonance imaging (MRI) potentially depends on the measurement position and presence of a patient inside the scanner bore.
To analyze the spatial characteristics of the acoustic noise by using the gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) with and without a human-body phantom on the examination table.
Acoustic noise waveforms were acquired at 80 and 110 measurement positions with and without a phantom. The GPAN-TFs µPa/(mT/m) in the coils were calculated by deconvolution. The phantom effect on the spatial distribution of the acoustic noise was assessed using the peak sound pressure levels (SPLs), mean values, peak values, and peak frequencies of the GPAN-TFs.
The peak SPLs in all positions for the X-, Y-, and Z-gradient coils were increased by 11.1 dB, 1.4 dB, and 6.1 dB, respectively, compared with the peak SPL of the magnetic isocenter. The maximum peak SPLs among all positions of the X-, Y-, and Z-gradient coils with the phantom were increased by 4.9 dB, 7.4 dB, and 6.9 dB, respectively, relative to those without the phantom. However, the peak SPLs decreased at some positions with the phantom placed on the table (X-gradient coil = 4.6 dB, Y-gradient coil = 5.0 dB, Z-gradient coil = 8.4 dB). The most common peak frequencies were in the range of 2000-3000 Hz.
"Hotspot" areas with and without the phantom were associated with acoustic noise sources in the clinical MRI scanner and were enhanced by the phantom's presence.
磁共振成像（MRI）中的声学噪声可能取决于测量位置以及扫描孔内患者的存在情况。
通过使用梯度脉冲到声学噪声传递函数（GPAN-TF），分析检查台上有无人体模型时声学噪声的空间特征。
在有和没有模型的情况下，于80个和110个测量位置采集声学噪声波形。通过去卷积计算线圈中的GPAN-TF（μPa/(mT/m)）。使用GPAN-TF的峰值声压级（SPL）、平均值、峰值和峰值频率评估模型对声学噪声空间分布的影响。
与磁等中心的峰值SPL相比，X、Y和Z梯度线圈在所有位置的峰值SPL分别增加了11.1 dB、1.4 dB和6.1 dB。有模型时，X、Y和Z梯度线圈在所有位置中的最大峰值SPL相对于无模型时分别增加了4.9 dB、7.4 dB和6.9 dB。然而，当模型放置在检查台上时，某些位置的峰值SPL下降（X梯度线圈 = 4.6 dB，Y梯度线圈 = 5.0 dB，Z梯度线圈 = 8.4 dB）。最常见的峰值频率在2000 - 3000 Hz范围内。
有无模型时的“热点”区域与临床MRI扫描仪中的声学噪声源相关，并且模型的存在会增强这些区域。
