Magnetic Resonance Imaging to Visualize Stroke and Characterize Stroke Recovery: A Review

Abstract

The global burden of stroke continues to grow. Although stroke prevention strategies (e.g., medications, diet, and exercise) can contribute to risk reduction, options for acute interventions (e.g., thrombolytic therapy for ischemic stroke) are limited to the minority of patients. The remaining patients are often left with profound neurological disabilities that substantially impact quality of life, economic productivity, and increase caregiver burden. In the last decade, however, the future outlook for such patients has been tempered by movement toward the view that the brain is capable of reorganizing after injury. Many now view brain recovery after stroke as an area of scientific research with large potential for therapeutic advances, far into the future (Broderick and William, 2004). As a probe of brain anatomy, function and physiology, magnetic resonance imaging (MRI) is a non-invasive and highly versatile modality that promises to play a particularly important role in such research. Here we provide a basic review of MRI physical principles and applications for assessing stroke, looking toward the future role MRI may play in improving stroke rehabilitation methods and stroke recovery.

Post-stroke Fatigue and Depressive Symptoms Are Differentially Related to Mobility and Cognitive Performance

“…Patients were selected within 6 months of stroke, and longer-term studies will also be required. Neuroimaging and fluid biomarker data were unavailable; therefore we are unable to address possible neuroanatomical and inflammatory bases for the current findings (Macintosh and Graham, 2013 ; Bensimon et al, 2014 ). Although the FAS is a well-established measure, we cannot comment on how the findings might map onto other fatigue instruments.…”

Indirect MRI of 17o‐labeled water using steady‐state sequences: Signal simulation and preclinical experiment

“…Signal amplitudes of balanced steady‐state free precession (bSSFP) were simulated via the following equation: where M 0 is equilibrium magnetization, which is assumed to be unity, and θ is flip angle (FA), , and . In the simulation at 3T, respective T 1 /T 2 values of 3817/1442 msec, 1820/99 msec, and 1084/69 msec were used for CSF, gray matter (GM), and white matter (WM) . To determine the optimal FA, those signals were simulated with repetition time / echo time (TR/TE) of 2.6/1.2 msec, and various FAs (5–120°).…”

“…2;H are the respective proton transverse relaxation times of H 16 2 O and H 17 2 O, and P is the molar fraction of H 17 2 O (the same as the 17 O concentration). In this simulation, T 2,H was calculated at various values of P (0.037-1.600%).…”

Cerebral Perfusion Measurements in Elderly with Hypertension Using Arterial Spin Labeling

“…CBF crushed may be preferable to CBF non-crushed , since micro-vascular CBF changes are generally assumed to reflect (patho-)physiological changes in neuronal activity and energy demand whereas macro-vascular CBF is believed to be dominated by cardiovascular fluctuation [ 7 ]. ATT has been shown to be able to provide additional diagnostic value to CBF measurements, especially in cerebrovascular pathology [ 8 , 9 ]. Compared to the measurement of ATT with multiple time point approaches (multi-TI), advantages of FEAST include whole-brain coverage, relatively high SNR [ 10 ], relatively low motion sensitivity and relatively low computational demand [ 6 ].…”