Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 The importance of specific diagnosis in stroke patient management
- 2 Limitations of current brain imaging modalities in stroke
- 3 Clinical efficacy of CT in acute cerebral ischemia
- 4 Computerized tomographic-based evaluation of cerebral blood flow
- 5 Technical introduction to MRI
- 6 Clinical use of standard MRI
- 7 MR angiography of the head and neck: basic principles and clinical applications
- 8 Stroke MRI in intracranial hemorrhage
- 9 Using diffusion-perfusion MRI in animal models for drug development
- 10 Localization of stroke syndromes using diffusion-weighted MR imaging (DWI)
- 11 MRI in transient ischemic attacks: clinical utility and insights into pathophysiology
- 12 Perfusion-weighted MRI in stroke
- 13 Perfusion imaging with arterial spin labelling
- 14 Clinical role of echoplanar MRI in stroke
- 15 The ischemic penumbra: the evolution of a concept
- 16 New MR techniques to select patients for thrombolysis in acute stroke
- 17 MRI as a tool in stroke drug development
- 18 Magnetic resonance spectroscopy in stroke
- 19 Functional MRI and stroke
- Index
- Plate Section
15 - The ischemic penumbra: the evolution of a concept
Published online by Cambridge University Press: 26 August 2009
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 The importance of specific diagnosis in stroke patient management
- 2 Limitations of current brain imaging modalities in stroke
- 3 Clinical efficacy of CT in acute cerebral ischemia
- 4 Computerized tomographic-based evaluation of cerebral blood flow
- 5 Technical introduction to MRI
- 6 Clinical use of standard MRI
- 7 MR angiography of the head and neck: basic principles and clinical applications
- 8 Stroke MRI in intracranial hemorrhage
- 9 Using diffusion-perfusion MRI in animal models for drug development
- 10 Localization of stroke syndromes using diffusion-weighted MR imaging (DWI)
- 11 MRI in transient ischemic attacks: clinical utility and insights into pathophysiology
- 12 Perfusion-weighted MRI in stroke
- 13 Perfusion imaging with arterial spin labelling
- 14 Clinical role of echoplanar MRI in stroke
- 15 The ischemic penumbra: the evolution of a concept
- 16 New MR techniques to select patients for thrombolysis in acute stroke
- 17 MRI as a tool in stroke drug development
- 18 Magnetic resonance spectroscopy in stroke
- 19 Functional MRI and stroke
- Index
- Plate Section
Summary
Definition
In human ischemic stroke the affected brain tissue has metabolic requirements that can no longer be supported by a sudden interruption, or at least reduction, in nutrient supply and waste disposal resulting from disease in a proximal artery. The underlying pathophysiological changes immediately following arterial occlusion include an initial loss of neuronal electrical activity followed by depletion of cellular energy stores and the loss of the transmembrane ion pumps which maintain water, sodium, chloride and potassium balance. Cellular necrosis will follow these changes if the cell's minimum energy requirements are not met. The tissue supplied by the artery is not affected homogeneously by this process, and critical blood flow thresholds associated with irreversible tissue infarction, functional tissue impairment, or benign oligemia can be identified. Several methods of threshold detection using modern imaging techniques lead to differing interpretations of this in vivo, and the extensive molecular and biochemical mechanisms in the penumbra can only partially be evaluated in human stroke patients. The region of incomplete ischemia in stroke usually adjacent to the area of profound ischemia has been termed the ischemic penumbra. A useful functional definition of the penumbra is that region of under-perfused brain tissue that is metabolically impaired, classically showing electrical inactivity, but with cellular morphology intact. In humans, this region is closely associated with established critical thresholds for blood flow rates using positron emission tomography (PET).
Keywords
- Type
- Chapter
- Information
- Magnetic Resonance Imaging in Stroke , pp. 191 - 206Publisher: Cambridge University PressPrint publication year: 2003
- 1
- Cited by