Department of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.
Philips Healthcare, Best, Netherlands.
MAGMA. 2024 Aug;37(4):621-636. doi: 10.1007/s10334-024-01162-x. Epub 2024 May 14.
To investigate the effect of respiratory motion in terms of signal loss in prostate diffusion-weighted imaging (DWI), and to evaluate the usage of partial Fourier in a free-breathing protocol in a clinically relevant b-value range using both single-shot and multi-shot acquisitions.
A controlled breathing DWI acquisition was first employed at 3 T to measure signal loss from deep breathing patterns. Single-shot and multi-shot (2-shot) acquisitions without partial Fourier (no pF) and with partial Fourier (pF) factors of 0.75 and 0.65 were employed in a free-breathing protocol. The apparent SNR and ADC values were evaluated in 10 healthy subjects to measure if low pF factors caused low apparent SNR or overestimated ADC.
Controlled breathing experiments showed a difference in signal coefficient of variation between shallow and deep breathing. In free-breathing single-shot acquisitions, the pF 0.65 scan showed a significantly (p < 0.05) higher apparent SNR than pF 0.75 and no pF in the peripheral zone (PZ) of the prostate. In the multi-shot acquisitions in the PZ, pF 0.75 had a significantly higher apparent SNR than 0.65 pF and no pF. The single-shot pF 0.65 scan had a significantly lower ADC than single-shot no pF.
Deep breathing patterns can cause intravoxel dephasing in prostate DWI. For single-shot acquisitions at a b-value of 800 s/mm, any potential risks of motion-related artefacts at low pF factors (pF 0.65) were outweighed by the increase in signal from a lower TE, as shown by the increase in apparent SNR. In multi-shot acquisitions however, the minimum pF factor should be larger, as shown by the lower apparent SNR at low pF factors.
研究在前列腺弥散加权成像（DWI）中由于呼吸运动导致的信号丢失的影响，并评估在临床相关 b 值范围内使用单次激发和多激发采集时，部分傅里叶在自由呼吸方案中的应用。
首先在 3T 上进行控制呼吸 DWI 采集，以测量深呼吸模式下的信号丢失。在自由呼吸方案中，采用无部分傅里叶（无 pF）和部分傅里叶（pF）因子为 0.75 和 0.65 的单激发和多激发（2 次激发）采集。在 10 名健康志愿者中评估表观 SNR 和 ADC 值，以测量低 pF 因子是否会导致低表观 SNR 或高估 ADC。
控制呼吸实验显示了浅呼吸和深呼吸之间信号变异系数的差异。在自由呼吸的单激发采集中，pF 0.65 扫描在前列腺外周区（PZ）的表观 SNR 明显（p<0.05）高于 pF 0.75 和无 pF。在 PZ 的多激发采集中，pF 0.75 的表观 SNR 明显高于 0.65 pF 和无 pF。单激发 pF 0.65 扫描的 ADC 明显低于单激发无 pF。
深呼吸模式会导致前列腺 DWI 中的体素内去相位。对于 b 值为 800 s/mm 的单激发采集，低 pF 因子（pF 0.65）下运动相关伪影的潜在风险可以通过更低的 TE 增加信号来抵消，这可以通过表观 SNR 的增加来体现。然而，在多激发采集中，最小 pF 因子应该更大，因为在低 pF 因子下，表观 SNR 较低。
