Noninvasive measurement of oxygenation using quantitative susceptibility mapping

项目摘要/摘要 本研究的目的是建立心脏定量敏感性图(QSM)，用于非侵入性测量。 测量血氧饱和度，以达到提高早期诊断和治疗的长期目标 肺高压(PH)患者的决策和临床结果。博士是一位进步的和 影响约10%65岁以上成年人的寿命缩短障碍。鉴于PH在其后期阶段可能是不可逆转的， 早期诊断和生理监测至关重要。肺和心脏的氧合受损 房室(心脏氧合)是PH的关键表现，影响症状和临床结果。 PH时肺动脉压升高损害肺氧交换，减少氧输送。 将基因血液注入左心。体循环心输出量在PH时经常受损，导致较大的差异。 左右心脏之间的血氧饱和度。有创导管插入术(Cath)目前用于 测量心脏氧合，但存在程序风险、电离辐射暴露，而且早期测量是不切实际的 诊断和连续监测-一种非侵入性的准确测量血氧含量的方法 有很大的实用性。MRI非常适合于肺高压的评估，因为它可以综合评估肺解剖结构。 OMY，压力，以及心功能和重塑-血氧是MRI评估的一个关键缺陷 pH值这一差距源于当前脉冲序列技术的局限性，而不是核磁共振基础物理。 众所周知，脱氧作用会改变血液的磁化率。这些变化是有传统的- 使用MR信号的幅度属性：横向弛豫时间(T2)来探测。不过，这个 需要针对患者的校准，这在临床实践中是困难的。相比之下，QSM依赖于 磁共振信号可直接测量敏感度，从而测量心脏氧合。我们已经获得了极大的鼓舞 心脏血氧的QSM测量的初步数据，QSM和QSM之间的一致性很好 氧合作用进行了侵入性测量。我们已经确定了发展心脏QSM的关键挑战，包括 运动抑制和延长的扫描时间。目前的研究建议开发一种加速心脏 QSM方法，并测试QSM与侵入性导管氧合的关系，以及努力耐受性和临床 预后。研究目标如下：(1)利用自由呼吸获得和开发加速心脏QSM 优化重构。(2)在PH患者中测试加速和现行心脏QSM，并与 以T2为基础的心脏氧合和有创心导管术的参考标准。(三)确定 心脏QSM是否分层显示临床严重程度并预测PH疾病的进展。预期的结果 这项研究是一种测量心脏氧合的非侵入性方法--心脏氧合是PH的关键标志 这目前依赖于侵入性测试。鉴于这一严重疾病的患病率和治疗选择不断增加 条件，心脏QSM无创氧合评估具有广泛的意义 数百万PH患者的早期诊断、治疗优化和临床结果的改善。

PROJECT SUMMARY/ABSTRACT The goal of this research is to develop cardiac quantitative susceptibility mapping (QSM) for non-invasive meas- urement of blood oxygen saturation, towards the long-term objective of improving early diagnosis, therapeutic decision-making, and clinical outcomes for patients with pulmonary hypertension (PH). PH is a progressive and life shortening disorder affecting ~10% of adults over age 65. Given that PH can be irreversible in its later stages, early diagnosis and physiologic monitoring are critically important. Impaired oxygenation of the lungs and heart chambers (cardiac oxygenation) is a key manifestation of PH that impacts symptoms and clinical outcomes. Increased pulmonary arterial pressure in PH impairs pulmonary oxygen exchange, decreasing delivery of oxy- genated blood to the left heart. Systemic cardiac output is often compromised in PH, resulting a larger differential blood oxygen saturation between the left and right heart. Invasive catheterization (cath) is currently used to measure cardiac oxygenation but entails procedural risks, ionizing radiation exposure, and is impractical for early diagnosis and serial monitoring - a non-invasive method to accurately measure blood oxygenation would be of substantial utility. MRI is well suited for PH assessment as it enables integrated evaluation of pulmonary anat- omy, pressure, as well as cardiac function and remodeling - blood oxygenation is a key gap in MRI evaluation of PH. This gap stems from limitations in current pulse sequence technology rather than fundamental MRI physics. It is well known that deoxygenation changes the magnetic susceptibility of blood. These changes have tradition- ally been probed using a magnitude property of the MR signal: the transverse relaxation time (T2). However, this requires patient-specific calibration that is difficult in clinical practice. In contrast, QSM relies on the phase of the MR signal to directly measure susceptibility and thus cardiac oxygenation. We have obtained highly encouraging preliminary data for QSM measurement of cardiac blood oxygenation, with close agreement between QSM and oxygenation measured invasively. We have identified key challenges for developing cardiac QSM, including motion suppression and prolonged scan times. The current research proposes to develop an accelerated cardiac QSM method, and to test QSM in relation to oxygenation on invasive cath, as well as effort tolerance and clinical prognosis. Study Aims are as follows: (1) Develop accelerated cardiac QSM using free-breathing acquisition and optimized reconstruction. (2) Test accelerated and current cardiac QSM among PH patients in comparison to T2-based cardiac oxygenation and the reference standard of invasive cardiac catheterization. (3) Determine whether cardiac QSM stratifies clinical severity and predicts PH disease progression. The expected outcome of this research is a non-invasive method for measuring cardiac oxygenation – a critically important marker in PH that currently relies on invasive testing. Given the increasing prevalence and therapeutic options for this serious condition, non-invasive oxygenation assessment by cardiac QSM holds broad significance towards the goal of early diagnosis, therapy optimization, and improved clinical outcomes for millions of patients with PH.