多呼吸超极化氦成像方案测量肺泡氧张力和表观扩散系数。
Multibreath Hyperpolarized He Imaging Scheme to Measure Alveolar Oxygen Tension and Apparent Diffusion Coefficient.
机构信息
Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.
Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania.
出版信息
Acad Radiol. 2019 Mar;26(3):367-382. doi: 10.1016/j.acra.2018.10.001. Epub 2019 Jan 8.
RATIONALE AND OBJECTIVES
In this study, we compared a newly developed multibreath simultaneous alveolar oxygen tension and apparent diffusion coefficient (PO-ADC) imaging sequence to a single-breath acquisition, with the aim of mitigating the compromising effects of intervoxel flow and slow-filling regions on single-breath measurements, especially in chronic obstructive pulmonary disease (COPD) subjects.
MATERIALS AND METHODS
Both single-breath and multibreath simultaneous PO-ADC imaging schemes were performed on a total of 10 human subjects (five asymptomatic smokers and five COPD subjects). Estimated PO and ADC values derived from the different sequences were compared both globally and regionally. The distribution of voxels with nonphysiological values was also compared between the two schemes.
RESULTS
The multibreath protocol decreased the ventilation defect volumes by an average of 12.9 ± 6.6%. The multibreath sequence generated nonphysiological PO values in 11.0 ± 8.5% fewer voxels than the single-breath sequence. Single-breath PO maps also showed more regions with gas-flow artifacts and general signal heterogeneity. On average, the standard deviation of the PO distribution was 16.5 ± 7.0% lower using multibreath PO-ADC imaging, suggesting a more homogeneous gas distribution. Both mean and standard deviation of the ADC increased significantly from single- to multibreath imaging (p = 0.048 and p = 0.070, respectively), suggesting more emphysematous regions in the slow-filling lung.
CONCLUSION
Multibreath PO-ADC imaging provides superior accuracy and efficiency compared to previous imaging protocols. PO and ADC maps generated by multibreath imaging allowed for the qualification of various regions as emphysematous or obstructed, which single-breath PO maps can only identify as defects. The simultaneous PO and ADC measurements generated by the presented multibreath method were also more physiologically realistic, and allowed for more detailed analysis of the slow-filling regions characteristic of COPD subjects.
背景与目的
本研究旨在比较一种新开发的多呼吸同步肺泡氧分压和表观弥散系数（PO-ADC）成像序列与单次呼吸采集，以减轻呼吸间流动和缓慢填充区域对单次呼吸测量的不利影响，特别是在慢性阻塞性肺疾病（COPD）患者中。
材料与方法
共对 10 名健康受试者（5 名无症状吸烟者和 5 名 COPD 患者）进行了单次呼吸和多呼吸同步 PO-ADC 成像方案。比较了不同序列得出的 PO 和 ADC 值的全局和局部估计值。还比较了两种方案之间具有非生理值的体素分布。
结果
多呼吸方案使通气缺陷体积平均减少了 12.9±6.6%。多呼吸序列产生的非生理 PO 值比单次呼吸序列少 11.0±8.5%。单次呼吸 PO 图还显示出更多的气流伪影和总体信号异质性区域。多呼吸 PO-ADC 成像时，PO 分布的标准偏差平均降低了 16.5±7.0%，表明气体分布更均匀。从单次呼吸到多呼吸成像，平均和标准偏差的 ADC 均显著增加（p=0.048 和 p=0.070），表明在缓慢填充的肺中有更多的气肿区域。
结论
与以前的成像方案相比，多呼吸 PO-ADC 成像具有更高的准确性和效率。多呼吸成像生成的 PO 和 ADC 图可以对各种区域进行定性为气肿或阻塞，而单次呼吸 PO 图只能将其识别为缺陷。所提出的多呼吸方法生成的同步 PO 和 ADC 测量结果也更符合生理现实，并且允许对 COPD 患者特征的缓慢填充区域进行更详细的分析。
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