|Year : 2014 | Volume
| Issue : 3 | Page : 566-569
The value of diffusion-weighted imaging in prediction of outcome of transient ischemic attacks
M Ezzat Elwan1, M Salah-Eldeen Elzawawy2, Rasha A El-Kabany1, Ibrahim E Alahmar1, Eman S Matar MBBCh 1
1 Department of Neuropscychiatry, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Clinical Radiology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||01-Dec-2013|
|Date of Acceptance||02-Mar-2013|
|Date of Web Publication||26-Nov-2014|
Eman S Matar
Department of Neuropscychiatry, Faculty of Medicine, Menoufia University, Yassin Abd El Ghaffar Street, Shebin El Kom, Menoufia
Source of Support: None, Conflict of Interest: None
The aim of the study was to study the clinical significance of diffusion-MRI in the prediction of outcome of transient ischemic attacks (TIAs) and its relation to the risk factors and TIA clinical presentations.
Diffusion-weighted imaging (DWI) observations in TIA patients led to the proposal for a new definition of TIA, which is called the 'tissue-based' TIA definition, so that patients with clinical symptoms of focal brain with acute DWI-lesions, irrespective of the neurological signs duration, had a stroke rather than TIA.
Patients and methods
The participants in this study were classified into two groups: patient group (group I) and control group (group II) (n = 20) of normal individuals. The patients in group I (n = 35) were those who had had recent TIAs for the first time for whom an initial brain DWI was performed within 48 h after the onset of TIA and a follow-up one 3 months later for those with initial positive DWI.
Initial DWI lesions were detected in nine (25.7%) patients; it was found that those with TIA duration 1 h or more, with mainly AF or carotid artery stenosis more than 50% and presenting clinically with aphasia or motor manifestations, had lesions on DWI.
TIA patients with duration of symptoms 1 h or more, atrial fibrillation or carotid artery stenosis more than 50% risk factors, and presenting clinically with motor deficits or aphasia had DWI positivity and thus an increased risk of developing stroke.
Keywords: duration, diffusion-weighted imaging, presentation, transient ischemic attack
|How to cite this article:|
Elwan M E, Elzawawy M S, El-Kabany RA, Alahmar IE, Matar ES. The value of diffusion-weighted imaging in prediction of outcome of transient ischemic attacks. Menoufia Med J 2014;27:566-9
|How to cite this URL:|
Elwan M E, Elzawawy M S, El-Kabany RA, Alahmar IE, Matar ES. The value of diffusion-weighted imaging in prediction of outcome of transient ischemic attacks. Menoufia Med J [serial online] 2014 [cited 2020 Sep 20];27:566-9. Available from: http://www.mmj.eg.net/text.asp?2014/27/3/566/145514
| Introduction|| |
A brief episode of neurologic dysfunction presumptively caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than 1 h, is the traditional definition of transient ischemic attack (TIA)  . MRI using diffusion-weighted imaging (DWI) within 24-48 h from the onset of the TIA shows an ischemic lesion in ~50% of all TIA patients, with the probability of DWI positivity increasing with the duration of symptoms  .
Therefore, a new definition of TIA has been proposed as a brief episode of neurologic dysfunction presumptively caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than 1 h, and without neuroimaging evidence of acute infarction; the corollary is that persistent clinical signs or characteristic imaging abnormalities define infarction  .
| Patients and methods|| |
This study was carried out on 35 patients admitted to the Neurology Department, Menoufia University, from November 2011 till September 2012 and a control group of normal individuals matched for age and sex (n = 20). Each participant in this study was subjected to a full assessment of history, complete general and neurological examination, and the following investigations: routine blood biochemistry, ECG, transesophageal echocardiography, carotid duplex ultrasonography, and brain diffusion-MRI. Initial diffusion-weighted-MRI scans were performed within 48 h from the onset of TIA and a follow-up one 3 months later for those with initial positive DWI scans using echo-planar imaging on a 1.5-T magnet (Titan Excelart Vantage Series). DWI scan was considered positive if the scan indicated an area of hyperintensity on DWI and hypointensity on the apparent diffusion coefficient map relative to the normal brain, indicating acute cerebral ischemia. All scans were reviewed by a board-certified radiologist during the patients' hospitalization.
| Results|| |
The age range of the patients in group I was between 48 and 72 years (mean age 59.2 ± 7.9 years); there were 22 (62.9%) men and 13 (37.14%) women ([Table 1], [Table 2] and [Table 3]). The range of duration of symptoms was between 0.15 and 6 h (mean duration 1.8 ± 3.4 h). The time range from the onset of TIA symptoms to the initial MRI study was 3-48 h (mean 15.3 ± 12.0 h). DWI initial lesions were detected in nine (25.7%) patients, five (55.6%) men and four (44.4%) women (mean age 60 ± 7.9 years); TIA duration in these patients was 1 h or more in 63.6% and less than 1 h in only 8.3% ([Table 4]). The mean time delay to DWI after the onset of TIA was 14.1 ± 12.9 h ([Table 5]). They mainly had atrial fibrillation (33.3%), more than 50% carotid artery stenosis (44.4%), hypertension (11.1%), and a combination of hypertension and more than 50% carotid artery stenosis (11.1%) as risk factors for their TIAs ([Figure 1]). The clinical presentations of their TIAs were mainly in the form of aphasia (22.2%), motor weakness (44.4%), aphasia and motor weakness (22.2%), and sensorimotor manifestations (1.1%) ([Figure 2], [Figure 3] and [Figure 4]). All lesions were unilateral and involved the distribution of the anterior cerebral circulation (100%); none of the patients had lesions that involved the distribution of the posterior cerebral circulation. On follow-up DWI performed 3 months later for those with initial positive DWI, two (22.2%) patients had permanent lesions corresponding to the initial ones ([Figure 5]).
|Figure 1: Risk factors of group I. DM, diabetes mellitus; DWI, diffusion-weighted imaging; HTN, hypertension.|
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|Figure 5: Time changes of diffusion-weighted imaging (DWI) signal intensity. ADC, apparent diffusion coefficient.|
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|Table 3: Diffusion-weighted imaging findings in patient group I and the control group II |
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|Table 4: Durations of transient ischemic attacks in positive diffusion-weighted imaging versus negative scans, group I |
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|Table 5: Time delay to MRI in positive diffusion-weighted imaging versus negative scans, group |
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| Discussion|| |
In this study, statistical significance was found for the duration of TIA symptoms (≥1 h) and the presence of ischemic lesions on DWI, and this result is in agreement with that of Rapposelli  , Purroy et al.  , and Olivot and Albers  , who found that prolonged TIA duration (≥60 min) was observed more frequently in the positive group than in the negative group. They found that the duration of TIA reflects the severity of brain ischemia and the probability of infarct increases with increasing duration of symptoms, so that the shorter the duration of symptoms of TIAs, the more reversible the DWI lesions or negative DWI scans.
It was found that there was no statistical significance for the delay from the onset of TIA to the initial DWI and the presence of DWI-related lesions. This result is in agreement with that of Lamy et al.  who performed DWI within 48 h from the onset of symptoms, Ay et al.  , in whose study, the mean delay from the onset of TIA to having DWI was 30 ± 33 h, and Inatomi et al.  , who performed DWI for their TIA patients within 14 days after the onset of TIAs. This result is not in agreement with the result of Rapposelli  , who found that positivity for lesions on DWI was more common among patients who had an MR scan within 24 h of symptom resolution than among patients who had an MR scan beyond the 24-h postresolution time frame.
Patients with TIA-related lesions (positive DWI) mainly had atrial fibrillation and/or carotid artery stenosis 50% or more as risk factors than patients with negative DWI scans; this result is in agreement with the results of Calvet et al.  , Prabhakaran et al.  , and Inatomi et al.  , who found similar results. The result of this study is not in agreement with that of Nagura et al.  , who found that DWI abnormalities were closely related to intracranial vascular occlusive lesions; no other risk factors including cardiac diseases differed significantly between the DWI-positive and the DWI-negative patient groups.
Patients with positive DWI scans were those who clinically experienced aphasia and/or motor manifestations of their TIAs more than those with negative DWI scans. This result is in agreement with the results of Merwick et al.  , Shah et al.  , Redgrave et al.  , and Oppenheim et al.  , who found similar results. Olivot and Albers  found that in TIA patients with clinical presentations in the form of syncope, ataxia, and/or sensory manifestations, there was no association with a positive DWI scan. They explained that sensory manifestations are often viewed as 'soft' symptoms because they are subjective. In addition, sensory symptoms may be associated with a broad range of possible etiologies such as hyperventilation, seizure, migraine, or multiple sclerosis. This may explain why patients presenting with sensory symptoms did not have a greater likelihood of abnormal DWI. The same reasoning may also hold true for other nonspecific symptoms such as syncope; the latter symptom is often associated with brain stem lesions, which are known to be more difficult to detect with MRI than hemispheric abnormalities  .
We found that there was no statistical significance for repeated TIAs and DWI positivity; this result is in agreement with the result of Shah et al.  and Oppenheim et al.  , who found similar results.
Two (22.2%) patients from those with initial positive DWI (n = 9) had permanent DWI lesions corresponding to the initial ones on follow-up DWI performed 3 months later. The percentage of the presence of irreversible DWI lesions in this study is lower than that of Oppenheim et al.  ; in their study, of 33 patients with initial positive DWI who had an MRI follow-up with a delay from TIA onset (3-6 months), infarcts in regions corresponding to the original DWI abnormalities were found in 26 (79%) patients.
| Conclusion|| |
In TIA patients with duration of symptoms 1 h or more, atrial fibrillation or carotid stenosis as risk factors, motor deficits, and aphasia were each associated independently with lesions in DWI.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]