Quantitative Lung Function Assessment in 2-year old children after Congenital Diaphragmatic Hernia using Fourier Decomposition Magnetic Resonance Imaging

先天性横隔疝(CDH)导致腹部器官突出进入胸腔，从而导致肺发育障碍，继而肺发育不全。如果没有严重的其他畸形或综合征，肺发育不良和肺动脉高压是CDH患者生存结果的主要决定因素。肺发育不良不仅与呼吸道结构畸形有关，也与微血管系统功能障碍有关。在健康的儿童中，肺泡的数量增加到大约三岁，之后的肺生长是基于先前存在的肺泡的扩大。因此，CDH修复后儿童出生后肺组织发育可能是可能的。目前，肺灌注成像(MRI)的方法主要基于动态增强(DCE)或动脉自旋标记(ASL)技术。虽然DCE-MRI提供的信噪比(SNR)远高于ASL技术，但在应用造影剂及其潜在副作用方面的额外努力是不利的，特别是在患有肾脏疾病(即NSF)的患者。最近，也出现了一场重要的辩论，认为长期副作用可能与脑组织中基于Gd的造影剂的积累有关。因此，尤其是在儿童中，重复使用造影剂(例如，对于登记参加后续计划的CDH儿童)应该进行严格和个体化的评估。通过MRI，可以通过FD技术测量肺血流和肺通气量，而不需要电离辐射。我们的研究小组以前已经证明，在2岁儿童CDH后进行DCE测量是可能的，并检测到肺灌注值的侧向差异。此外，在成人患者中，无辐射和无造影剂的灌注和换气的定量，因此，V/Q成像已被证明是可行的FD-技术。因此，MRI既能显示肺形态，又能显示肺功能，是儿童CDH术后随访的合适工具。本研究的目的是将傅立叶分解技术应用于2岁儿童的肺部成像，并探讨呼吸图和灌注图在儿童先天性膈疝中的临床应用价值。这包括实施2D和3D成像技术和1.5T的后处理以及将其转换为3T，以及将灌注图与DCE-MRI进行关联。在临床上，这些技术的诊断价值，以及它检测对侧和同侧肺之间的灌注/换气变化的能力，以及最终描述联合定量灌注和换气显像对CDH患儿的患者治疗和相应的随访过程的意义。

Congenital diaphragmatic hernia (CDH) leads to herniation of abdominal organs into the thoracic cavity and consequently to impaired lung development, followed by lung hypoplasia. Lung hypoplasia and pulmonary hypertension are known to be the main determinants of survival outcome in cases of CDH if no severe additional malformations or syndromes are present. Lung hypoplasia is not only attributed to malformed airway structures but also to a dysfunctional micro vascular system. In healthy children the amount of alveoli increases until the age of about three and afterwards lung growth is based on the enlargement of preexistent alveoli. Therefore, postnatal development of lung tissue during childhood may be possible for children after CDH repair. Up to now, little is known to which extent the affected lung catches up.Current methods for perfusion weighted lung magnetic resonance imaging (MRI) are either based on dynamic contrast enhanced (DCE) MRI or arterial spin labeling (ASL) techniques. Although DCE-MRI offers much higher signal to noise ratio (SNR) than ASL techniques, the additional efforts in administering the contrast agent and its potential side-effects are disadvantages, especially in subjects with kidney disease (i.e. NSF). Recently, also a major debate has arisen which long-term side-effects may be associated to accumulation of gadolinium based contrast-agents in the brain. Therefore, especially in children the repetitive usage of contrast agent (e.g. for children with CDH enrolled into a follow-up program) should be evaluated critically and individually.With MRI lung perfusion and lung ventilation can be measured via the FD technique without the need for ionizing radiation. Our study group has demonstrated previously that DCE-measurements in 2-year old children after CDH are possible and detect side differences in lung perfusion values. Besides, in adult patients radiation free and contrast agent free quantification of perfusion and ventilation and thereby, V/Q imaging has been proven to be feasible by FD-techniques. Therefore, MRI is a suitable tool for follow-up of children after CDH, as being capable to visualize both lung morphology and lung function. The objectives of this research proposal is to implement the Fourier Decomposition technique for lung imaging in 2-year old children and to investigate the clinical value of the ventilation and perfusion maps for children with congenital diaphragmatic hernia. This comprises implementing 2D and 3D imaging techniques and post processing at 1.5T and its translation to 3T as well as correlation of the perfusion maps to DCE-MRI. Clinically, diagnostic value of the developed techniques, its power to detect changes in perfusion/ ventilation between contra- and ipsilateral lung and eventually describe implication of combined quantitative perfusion and ventilation imaging in CDH children on patient treatment and respectively follow-up procedure.