Analysis of improvements to post-stroke visual field mapping using prospective motion correction in fMRI

英国每年约有110，000例中风病例，中年男性中风的终生风险为1/6，中年女性为1/5。据估计，60%的中风幸存者在中风后立即遭受某种形式的视觉障碍。其中，三分之一的人在中风发作后三个月仍患有视力障碍。这种视觉障碍可以有一个显着的影响生活质量，因为它会导致缺乏流动性，信心的丧失和碰撞和事故的增加率。在正在进行的工作中，我们一直在使用磁共振成像（MRI），以确定备用皮层周围的枕叶病变的能力，以支持视力。通过功能性磁共振成像，我们一直在估计备用视觉皮层内不同区域的视野覆盖范围，并使用这些信息来训练参与者完成困难的视觉任务。除了功能性MRI，还有一套强大的附加技术可以提供重要的附加信息。然而，尽管如此，这些额外的测量在临床环境中从未组合使用。弥散加权成像-血管造影/灌注测量-高分辨率解剖扫描这些技术不经常组合的主要原因之一是参与者必须花费在MR扫描仪中的时间量以及与运动相关的问题和伪影。例如，由于中风后舞蹈病和震颤等运动障碍同时发生，许多中风幸存者可能无法从这种有针对性的干预中受益，因为这些疾病引起的不自主运动可能会导致运动伪影）MRI），因此也是所有成像数据。详细研究的好处提高数据质量的不同方法（和局限性）（前瞻性运动校正，并行成像，多波段，压缩传感）因此，fMRI衍生数据至关重要，并可能导致在使用何种成像协议来评估这些患者方面的切实改进。稳定磁共振成像（MRI）测量。特别是，我们将调查和量化目前使用的功能性MRI协议，弥散加权成像和血管造影/灌注测量可以通过使用并行成像来改进（例如SENSE）和多波段采集-基于导航回波的运动前瞻性校正-使用欠采样数据采集（压缩传感）-（时间允许的话）使用机器学习技术改善血管造影成像衍生测量的量化，方法学博士课程的启动计划如下。学生将：-比较目前使用的设置和成像协议（在3 T）成像中风幸存者和健康对照队列。调查质量改进（在健康参与者中）从当前使用的扫描仪移动（3 T Achieva）升级到更新的硬件平台，包括许多技术改进（3 T Ingenia）-使用2种互补并行成像方法评估成像加速和数据质量之间的权衡（SENSE和多波段）-通过使用计算密集型方法来使用欠采样数据，进一步研究加速（压缩感测，稀疏信号的重建），这将特别有益于血管造影术-评估通过加速和/或减少成像相关的声学噪声实现的患者舒适度的改善。这对我们发展患者和公众参与（PPI）尤为重要。与EPSRC的战略和研究领域保持一致-特定主题电话，涉及弱势受试者的成像技术。

There are approximately 110,000 stroke cases in England each year with the lifetime risk of a stroke for a middle-aged man being 1-in-6 and for a middle-aged woman being 1-in-5. It is estimated that 60% of stroke survivors suffer from some form of visual impairment immediately after a stroke. Of those, one in three still suffer from visual impairment three months post-stroke onset. This visual impairment can have a marked impact on quality of life, as it leads to a lack of mobility, loss of confidence and increased rates of collisions and accidents.In ongoing work we have been using magnetic resonance imaging (MRI) to identify spared cortex surrounding the lesions in the occipital lobe with capacity to support vision. With functional MRI, we have been estimating the visual field coverage of different areas within the spared visual cortex and using this information to train participants on a difficult visual task. In addition to functional MRI, there is a powerful set of additional techniques that can provide important additional information. Despite this however, these additional measurements are really never use in combination in the clinical setting.- diffusion weighted imaging - angiography/perfusion measurements - high resolution anatomical scansOne of the main reasons for these technologies are not often combined is the amount of time a participant has to spend in an MR scanner and problems and artefacts related to motion. For example, due to the co-occurrence of movement disorders such as chorea and tremors post-stroke, many stroke survivors may not be able to benefit from such a targeted intervention, since the involuntary movements caused by these disorders can cause motion artefacts in MRI) and therefore also all the imaging-dreived data. A detailed study of the benefits (and limits) of different approaches to improving data quality (prospective motion correction, parallel imaging, multiband, compressed sensing) for fMRI derived data is therefore crucially important and likely to lead to tangible improvements in what kind of imaging protocols are used to assess these patients.Aims and objectivesTo investigate and quantify the improvements attainable with new technologies aimed at speeding up and stabilising magnetic resonance imaging (MRI) measurements. In particular, we will investigate and quantify how currently used protocols for functional MRI, diffusion weighted imaging and angiography/perfusion measurements can be improved by- use of parallel imaging (e.g SENSE) and multiband acquisition- prospective correction for motion based on navigator echoes- using undersampled data acquisition (compressed sensing)- (time permitting) use of machine learning techniques to improve quantification of imaging-derived measures for angiography, etc.MethodologyThe plan for the start of the PhD program is as follows. The student will:- compare the currently used setup and imaging protocol (at 3T) for imaging a cohort of stroke survivors and healthy controls.- investigate the quality improvements (in healthy participants) of moving from currently used scanner (3T Achieva) to an updated hardware platform that includes many technical improvements (3T Ingenia)- assess the trade-off between imaging speed-up and data quality with 2 kinds of complementary parallel imaging approaches (SENSE and Multiband)- investigate further speed-ups by also using computationally intensive approaches to using undersample data (compressed sensing, reconstruction of sparse signals), which will be particularly beneficial for angiography- assess the improvements in patient comfort achieved by speeding up and/or reducing imaging related acoustic noise. This is particularly important for our development of Patient and Public Involvement (PPI).Alignment to EPSRC's strategies and research areas- specific thematic call, relating to Imaging technologies for vulnerable subjects.