Kanazawa University, Kodatsuno, Ishikawa, Japan.
Acad Radiol. 2011 Jan;18(1):101-6. doi: 10.1016/j.acra.2010.09.009.
Acoustic noise both in terms of its magnitude and frequency during magnetic resonance imaging (MRI) scan is influenced by imaging parameters and pulse sequences. It varies because of many different factors such as structure, materials, and magnetic field strength. The purpose of our study is to evaluate the characteristics of acoustic noise independent of MRI scan protocol by measuring a gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) at various MRI scanners.
We measured sound pressure levels in the frequency domain in a 0.4-T, seven 1.5-T, and three 3.0-T clinical MRI systems when applying a simple narrower trapezoidal gradient pulse. We calculated a GPAN-TF [μPa/(mT/m)] in each gradient coil (ie, X, Y, and Z-axis) by the deconvolution process.
GPAN-TF at a high-frequency range (1000-10,000 Hz) was larger than that at low frequency for all MRI (P<0.01) scanners except for a low static field machine. For high frequency (>1000 Hz), the 3.0-T MRI scanner had a larger GPAN-TF than that of 0.4-T and 1.5-T (P < .01). MR scanner with a vacuum chamber reduced GPAN-TF at a lower frequency (P < .01), but this effect decreased at higher frequency.
GPAN-TF analysis makes it possible to obtain more detailed information on acoustic noise properties among MRI scanners.
磁共振成像（MRI）扫描过程中的声噪声无论是在幅度还是频率方面都受到成像参数和脉冲序列的影响。它因结构、材料和磁场强度等许多不同因素而变化。我们研究的目的是通过在各种 MRI 扫描仪上测量梯度脉冲到声噪声传递函数（GPAN-TF）来评估独立于 MRI 扫描协议的声噪声特性。
当施加简单的较窄梯形梯度脉冲时，我们在 0.4-T、7 个 1.5-T 和 3 个 3.0-T 临床 MRI 系统中在频域测量声压级。我们通过反卷积过程计算每个梯度线圈（即 X、Y 和 Z 轴）的 GPAN-TF[μPa/（mT/m）]。
除了低静态场机器外，所有 MRI 扫描仪（P<0.01）的高频范围（1000-10000 Hz）的 GPAN-TF 均高于低频。对于高频（>1000 Hz），3.0-T MRI 扫描仪的 GPAN-TF 大于 0.4-T 和 1.5-T（P<0.01）。具有真空腔的 MR 扫描仪可降低低频时的 GPAN-TF（P<0.01），但这种影响在高频时会降低。
GPAN-TF 分析可获得有关 MRI 扫描仪之间声噪声特性的更详细信息。
