DWI and acute stroke prognosis: a simple approach
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神经科学杂志 2005年第9期
Analysis of DWI lesion patterns may identify stroke patients at high risk of complications
Keywords: acute stroke; diffusion weighted imaging; stroke recurrence
In the paper by Bang et al in this issue (see pages 1222–8), the authors deal with the possibility of predicting clinical outcome in stroke patients by considering the diffusion weighted imaging (DWI) lesion patterns. This is a new approach to MRI findings which gives more emphasis to the location of DWI alterations than to their volume or number.
Although thrombolysis is the most effective treatment for acute stroke, it is still limited to a few patients because of its strict temporal therapeutic window. It follows that most therapeutic efforts are devoted to controlling the neurologic and medical complications. Therefore, early identification of patients at high risk of complications could potentially help to differentiate acute stroke therapies by selecting those patients who should be monitored and treated more aggressively. Early identification could also thus help to allocate medical resources better.
A simple evaluation of the DWI lesion pattern showed that patients presenting with internal borderzone infarcts have a more unstable hospital course. This subgroup of stroke patients may have a particular pathophysiological condition, probably linked to a precarious haemodynamic state associated with the occurrence of large artery disease.
If these internal borderzone infarcts are located in the supraventricular and paraventricular areas, we might hypothesise an unstable penumbral state. This should mainly involve the white matter which has been recently shown to present areas of potentially salvageable tissue as well as similar resistance to ischaemia of grey matter.1 In addition, a PET comparative study has shown that a DWI lesion may contain not only tissue destined for infarction but also penumbral areas that may still be saved.2
Another major early neurological complication is stroke recurrence, with a fatal outcome in about one fourth of cases. Kang et al demonstrated by serial DWI studies that "radiological" recurrences occurred in about one third of patients in the acute phase of stroke.3 In other words, stroke appears to be a "dynamic" phenomenon not limited to a single event but the result of multiple local or distant ischaemic insults. In their study, recurrences occurred mainly in patients with large vessel atherosclerosis and were frequently clinically silent. Looking at clinically manifested recurrences, Bang et al have showed that a DWI alterations pattern of small cortical infarcts suggested a higher risk of recurrent strokes.
Recent sophisticated imaging studies have indicated the possibility of closer insights into the pathophysiology of acute ischaemic stroke and its relationship with clinical features. However, such studies frequently require dedicated devices and research teams. A simple approach such as analysis of DWI lesion patterns might provide additional useful criteria to identify a subgroup of patients at high risk of neurological complications who should be strictly monitored. If these observations are confirmed, they may provide new opportunities for a better definition of individual therapeutic interventions in the acute phase of ischaemic stroke.
REFERENCES
Falcao AL, Reutens DC, Markus R, et al. The resistance to ischemia of white and gray matter after stroke. Ann Neurol 2004;56 (5) :695–701.
Guadagno JV, Warburton EA, Aigbirhio FI, et al. Does the acute diffusion-weighted imaging lesion represent penumbra as well as core? A combined quantitative PET/MRI voxel-based study. J Cereb Blood Flow Metab 2004;24 (11) :1249–54.
Kang DW, Latour LL, Chalela JA, et al. Early and late recurrence of ischemic lesion on MRI: evidence for a prolonged stroke-prone state? Neurology 2004;63 (12) :2261–5.(V Di Piero)
Keywords: acute stroke; diffusion weighted imaging; stroke recurrence
In the paper by Bang et al in this issue (see pages 1222–8), the authors deal with the possibility of predicting clinical outcome in stroke patients by considering the diffusion weighted imaging (DWI) lesion patterns. This is a new approach to MRI findings which gives more emphasis to the location of DWI alterations than to their volume or number.
Although thrombolysis is the most effective treatment for acute stroke, it is still limited to a few patients because of its strict temporal therapeutic window. It follows that most therapeutic efforts are devoted to controlling the neurologic and medical complications. Therefore, early identification of patients at high risk of complications could potentially help to differentiate acute stroke therapies by selecting those patients who should be monitored and treated more aggressively. Early identification could also thus help to allocate medical resources better.
A simple evaluation of the DWI lesion pattern showed that patients presenting with internal borderzone infarcts have a more unstable hospital course. This subgroup of stroke patients may have a particular pathophysiological condition, probably linked to a precarious haemodynamic state associated with the occurrence of large artery disease.
If these internal borderzone infarcts are located in the supraventricular and paraventricular areas, we might hypothesise an unstable penumbral state. This should mainly involve the white matter which has been recently shown to present areas of potentially salvageable tissue as well as similar resistance to ischaemia of grey matter.1 In addition, a PET comparative study has shown that a DWI lesion may contain not only tissue destined for infarction but also penumbral areas that may still be saved.2
Another major early neurological complication is stroke recurrence, with a fatal outcome in about one fourth of cases. Kang et al demonstrated by serial DWI studies that "radiological" recurrences occurred in about one third of patients in the acute phase of stroke.3 In other words, stroke appears to be a "dynamic" phenomenon not limited to a single event but the result of multiple local or distant ischaemic insults. In their study, recurrences occurred mainly in patients with large vessel atherosclerosis and were frequently clinically silent. Looking at clinically manifested recurrences, Bang et al have showed that a DWI alterations pattern of small cortical infarcts suggested a higher risk of recurrent strokes.
Recent sophisticated imaging studies have indicated the possibility of closer insights into the pathophysiology of acute ischaemic stroke and its relationship with clinical features. However, such studies frequently require dedicated devices and research teams. A simple approach such as analysis of DWI lesion patterns might provide additional useful criteria to identify a subgroup of patients at high risk of neurological complications who should be strictly monitored. If these observations are confirmed, they may provide new opportunities for a better definition of individual therapeutic interventions in the acute phase of ischaemic stroke.
REFERENCES
Falcao AL, Reutens DC, Markus R, et al. The resistance to ischemia of white and gray matter after stroke. Ann Neurol 2004;56 (5) :695–701.
Guadagno JV, Warburton EA, Aigbirhio FI, et al. Does the acute diffusion-weighted imaging lesion represent penumbra as well as core? A combined quantitative PET/MRI voxel-based study. J Cereb Blood Flow Metab 2004;24 (11) :1249–54.
Kang DW, Latour LL, Chalela JA, et al. Early and late recurrence of ischemic lesion on MRI: evidence for a prolonged stroke-prone state? Neurology 2004;63 (12) :2261–5.(V Di Piero)