在辐射诱导的肺损伤大鼠模型中，使用超极化（129）Xe磁共振成像定量分析区域早期气体交换变化。
Quantification of regional early stage gas exchange changes using hyperpolarized (129)Xe MRI in a rat model of radiation-induced lung injury.
作者信息
Doganay Ozkan, Stirrat Elaine, McKenzie Charles, Schulte Rolf F, Santyr Giles E
机构信息
Department of Medical Biophysics, Western University, London, Ontario N6A5C1, Canada; Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A5C1, Canada; and Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom.
Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G1X8, Canada.
出版信息
Med Phys. 2016 May;43(5):2410. doi: 10.1118/1.4946818.
PURPOSE
To assess the feasibility of hyperpolarized (HP) (129)Xe MRI for detection of early stage radiation-induced lung injury (RILI) in a rat model involving unilateral irradiation by assessing differences in gas exchange dynamics between irradiated and unirradiated lungs.
METHODS
The dynamics of gas exchange between alveolar air space and pulmonary tissue (PT), PT and red blood cells (RBCs) was measured using single-shot spiral iterative decomposition of water and fat with echo asymmetry and least-squares estimation images of the right and left lungs of two age-matched cohorts of Sprague Dawley rats. The first cohort (n = 5) received 18 Gy irradiation to the right lung using a (60)Co source and the second cohort (n = 5) was not irradiated and served as the healthy control. Both groups were imaged two weeks following irradiation when radiation pneumonitis (RP) was expected to be present. The gas exchange data were fit to a theoretical gas exchange model to extract measurements of pulmonary tissue thickness (LPT) and relative blood volume (VRBC) from each of the right and left lungs of both cohorts. Following imaging, lung specimens were retrieved and percent tissue area (PTA) was assessed histologically to confirm RP and correlate with MRI measurements.
RESULTS
Statistically significant differences in LPT and VRBC were observed between the irradiated and non-irradiated cohorts. In particular, LPT of the right and left lungs was increased approximately 8.2% and 5.0% respectively in the irradiated cohort. Additionally, VRBC of the right and left lungs was decreased approximately 36.1% and 11.7% respectively for the irradiated cohort compared to the non-irradiated cohort. PTA measurements in both right and left lungs were increased in the irradiated group compared to the non-irradiated cohort for both the left (P < 0.05) and right lungs (P < 0.01) confirming the presence of RP. PTA measurements also correlated with the MRI measurements for both the non-irradiated (r = 0.79, P < 0.01) and irradiated groups (r = 0.91, P < 0.01).
CONCLUSIONS
Regional RILI can be detected two weeks post-irradiation using HP (129)Xe MRI and analysis of gas exchange curves. This approach correlates well with histology and can potentially be used clinically to assess radiation pneumonitis associated with early RILI to improve radiation therapy outcomes.
目的
通过评估照射肺与未照射肺之间气体交换动力学的差异，在单侧照射的大鼠模型中评估超极化（HP）（129）Xe磁共振成像（MRI）检测早期放射性肺损伤（RILI）的可行性。
方法
使用单次激发螺旋迭代水脂分解及回波不对称和最小二乘估计成像，测量两组年龄匹配的斯普拉格-道利大鼠左右肺的肺泡气腔与肺组织（PT）、PT与红细胞（RBC）之间的气体交换动力学。第一组（n = 5）使用（60）Co源对右肺进行18 Gy照射，第二组（n = 5）未照射，作为健康对照。两组在照射后两周进行成像，此时预计会出现放射性肺炎（RP）。将气体交换数据拟合到理论气体交换模型，以从两组大鼠的左右肺中提取肺组织厚度（LPT）和相对血容量（VRBC）的测量值。成像后，取出肺标本，通过组织学评估组织面积百分比（PTA），以确认RP并与MRI测量值相关联。
结果
照射组与未照射组之间在LPT和VRBC方面观察到统计学上的显著差异。特别是，照射组右肺和左肺的LPT分别增加了约8.2%和5.0%。此外，与未照射组相比，照射组右肺和左肺的VRBC分别降低了约36.1%和11.7%。与未照射组相比，照射组左右肺的PTA测量值均增加，左肺（P < 0.05）和右肺（P < 0.01）均证实存在RP。PTA测量值与未照射组（r = 0.79，P < 0.01）和照射组（r = 0.91，P < 0.01）的MRI测量值也相关。
结论
使用HP（129）Xe MRI和气体交换曲线分析可在照射后两周检测到局部RILI。这种方法与组织学相关性良好，有可能在临床上用于评估与早期RILI相关的放射性肺炎，以改善放射治疗效果。
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