Neuroimaging of Ischemic Stroke With CT and MRI
Acute ischemic stroke is the third leading cause of death and the major cause of significant disability in adults in the USA and Europe. The number of patients who are actually treated for acute ischemic stroke is disappointingly low, despite availability of effective treatments. A major obstacle is the short window of time following stroke in which therapies are effective. Modern imaging is able to identify the ischemic penumbra, a key concept in stroke physiology. Evidence is accumulating that identification of a penumbra enhances patient management, resulting in significantly improved outcomes. Moreover, unexpectedly large proportions of patients have a substantial ischemic penumbra beyond the traditional time window and are suitable for therapy. The widespread availability of modern MRI and computed tomography systems presents new opportunities to use physiology to guide ischemic stroke therapy in individual patients. This article suggests an evidence-based alternative to contemporary acute ischemic stroke therapy.
Acute stroke is the third leading cause of death, accounting for approximately one in 16 deaths in 2004 and is the leading cause of serious, long-term disability in the USA. Annually, around 780,000 people experience stroke, of which around 600,000 are first attacks. On average, every 40 s, someone in the USA has a stroke and, of these, 15-30% become permanently disabled. After a major trial published in the New England Journal of Medicine in 1995, tissue plasminogen activator (tPA) was approved by the US FDA for use as an intravenous agent in ischemic stroke. Concurrently, advances in neuroimaging, especially diffusion/perfusion MRI, demonstrated that a central concept of stroke physiology, the ischemic penumbra, could be identified clinically. Further developments in stroke therapy, such as intra-arterial chemical and mechanical recanalization and the emergence of high-speed computed tomography (CT) further advanced hopes for improved patient outcomes. However, expectations for a rapid conquest of ischemic stroke proved to be premature. Indeed, only a small proportion of potential patients receive therapy. Moreover, advanced neuroimaging is rarely used in the routine evaluation of these patients.
A potential reason for the current state of affairs is that time of stroke onset has become the preeminent factor in guiding therapy. This result may have had unintended, unexpected and unfortunate consequences. Perhaps the most important impact has been the unintended suppression of the use of physiologic information provided by modern neuroimaging to guide stroke therapy. The purpose of this review is to examine the current state of stroke diagnosis by imaging and current therapeutic options. Additionally, evidence will be presented for the use of advanced neuroimaging to improve treatments through its visualization of relevant physiology. We suggest that data published to date support the concept that treatment decisions should be based on the individual patient's pathophysiological condition as revealed by neuroimaging.
Abstract and Introduction
Abstract
Acute ischemic stroke is the third leading cause of death and the major cause of significant disability in adults in the USA and Europe. The number of patients who are actually treated for acute ischemic stroke is disappointingly low, despite availability of effective treatments. A major obstacle is the short window of time following stroke in which therapies are effective. Modern imaging is able to identify the ischemic penumbra, a key concept in stroke physiology. Evidence is accumulating that identification of a penumbra enhances patient management, resulting in significantly improved outcomes. Moreover, unexpectedly large proportions of patients have a substantial ischemic penumbra beyond the traditional time window and are suitable for therapy. The widespread availability of modern MRI and computed tomography systems presents new opportunities to use physiology to guide ischemic stroke therapy in individual patients. This article suggests an evidence-based alternative to contemporary acute ischemic stroke therapy.
Introduction
Acute stroke is the third leading cause of death, accounting for approximately one in 16 deaths in 2004 and is the leading cause of serious, long-term disability in the USA. Annually, around 780,000 people experience stroke, of which around 600,000 are first attacks. On average, every 40 s, someone in the USA has a stroke and, of these, 15-30% become permanently disabled. After a major trial published in the New England Journal of Medicine in 1995, tissue plasminogen activator (tPA) was approved by the US FDA for use as an intravenous agent in ischemic stroke. Concurrently, advances in neuroimaging, especially diffusion/perfusion MRI, demonstrated that a central concept of stroke physiology, the ischemic penumbra, could be identified clinically. Further developments in stroke therapy, such as intra-arterial chemical and mechanical recanalization and the emergence of high-speed computed tomography (CT) further advanced hopes for improved patient outcomes. However, expectations for a rapid conquest of ischemic stroke proved to be premature. Indeed, only a small proportion of potential patients receive therapy. Moreover, advanced neuroimaging is rarely used in the routine evaluation of these patients.
A potential reason for the current state of affairs is that time of stroke onset has become the preeminent factor in guiding therapy. This result may have had unintended, unexpected and unfortunate consequences. Perhaps the most important impact has been the unintended suppression of the use of physiologic information provided by modern neuroimaging to guide stroke therapy. The purpose of this review is to examine the current state of stroke diagnosis by imaging and current therapeutic options. Additionally, evidence will be presented for the use of advanced neuroimaging to improve treatments through its visualization of relevant physiology. We suggest that data published to date support the concept that treatment decisions should be based on the individual patient's pathophysiological condition as revealed by neuroimaging.
SHARE
