Korean J Radiol.  2011 Jun;12(3):280-288. 10.3348/kjr.2011.12.3.280.

Transient Ischemic Attack and Stroke Can Be Differentiated by Analyzing the Diffusion Tensor Imaging

• Tong T
• Zhenwei Y
• Xiaoyuan F

• KMID: 1122325
• DOI: http://doi.org/10.3348/kjr.2011.12.3.280

Abstract

OBJECTIVE
We wanted to differentiate between transient ischemic attack (TIA) and minor stroke using fractional anisotropy and three-dimensional (3D) fiber tractography.
MATERIALS AND METHODS
The clinical data, conventional magnetic resonance imaging (MRI), diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) were obtained for 45 TIA patients and 33 minor stroke patients. The fractional anisotrophy ratio (rFA) between the lesion and the mirrored corresponding contralateral normal tissue was calculated and analyzed. The spatial relationship between the lesion and the corticospinal tract (CST) was analyzed and the lesion sizes in the minor stroke patients and TIA patients were compared.
RESULTS
Twenty-two of the 45 TIA patients (49%) revealed focal abnormalities following DWI. The rFA was significantly lower (p < 0.05) in the stroke patients (0.71 +/- 0.29) compared to that of the TIA patients (1.05 +/- 0.37). The CST was involved in almost all stroke lesions, but it was not involved in 68% of the TIA lesions. The TIA patients had significantly lower CST injury scores (3.25 +/- 1.75) than did the stroke patients (8.80 +/- 2.39) (p = 0.004).
CONCLUSION
Our data indicate that TIA and minor stroke can be identified by analyzing the rFA and the degree of CST involvement, and this may also allow more accurate prediction of a patient's long-term recovery or disability.

Keyword

Magnetic resonance imaging; Diffusion tensor imaging; Transient ischemic attack; Stroke

MeSH Terms

Aged
Anisotropy
Area Under Curve
Chi-Square Distribution
Diagnosis, Differential
Diffusion Tensor Imaging/*methods
Female
Humans
Image Interpretation, Computer-Assisted
*Imaging, Three-Dimensional
Ischemic Attack, Transient/*pathology
Male
Middle Aged
ROC Curve
Sensitivity and Specificity
Stroke/*pathology

Figure

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  Fig. 1 Diffusion weighted imaging (A) and fractional anisotrophy (B) measurement in patient with transient ischemic attack (64-year-old man with transient right extremity weakness. Yet neurologic deficits were completely resolved in 6 h). Diffusion weighted imaging (C) and fractional anisotrophy (D) measurement in patient with stroke (50-year-old man with dysarthria and right extremity weakness). In transient ischemic attack patient, rAIb = 1000 was 1.58 and rFA was 0.89. In stroke patient, rAIb = 1000 was 2.25 and rFA was 0.57. rAIb = 1000 was significantly lower in transient ischemic attack patients compared with that of stroke patients, while rFA was significantly higher in transient ischemic attack patients compared with that of stroke patients. rAI = average signal intensity, rFA = fractional anisotrophy ratio

• 

  Fig. 2 Percentile rank map of rAIb = 1000 (A) and rFA (B) between transient ischemic attack and stroke patients at different time intervals. At all time intervals, rAIb = 1000 and rFA were significantly different in stroke patients as compared with those values in transient ischemic attack patients. rAI = average signal intensity, rFA = fractional anisotrophy ratio, TIA = transient ischemic attack

• 

  Fig. 3 Receiver operating characteristic curve analysis for rFA of transient ischemic attack and stroke patients. Area under curve shows good accuracy (0.86) for discriminating transient ischemic attack from stroke using rAI measurement on fractional anisotrophy maps. rAI = average signal intensity, rFA = fractional anisotrophy ratio, ROC curve = receiver operating characteristic curve, TIA = transient ischemic attack

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  Fig. 4 Diffusion weighted imaging and diffusion tensor imaging scans from transient ischemic attack patient (53-year-old man with transient right hemisensory loss, weakness and dysarthria. Yet neurologic deficits completely resolved in 2-4 hours.) A. Axial diffusion weighted imaging showed small hyperintense lesion near left cornu posterius ventriculi lateralis. B, C. Lesion volume was 2.87 cm3. Fiber tracts reconstructed in 3-dimensional space were superimposed on fractional anisotrophy map (B) and directional encoded color map (C). D, E. Fiber tract results showed corticospinal tract (orange) of affected cerebral hemisphere appeared near lesion, but it was not running through it.

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  Fig. 5 Diffusion weighted imaging and diffusion tensor imaging scans from stroke patient (62-year-old man with right extremity weakness). A, B. Axial diffusion weighted imaging (A) and apparent diffusion coefficient (B) showed small hyperintense lesion on left thalamus and internal capsule. Lesion volume was 3.12 cm3. C, D. Fiber tracts reconstructed in 3-dimensional space were superimposed on fractional anisotrophy map (C) and directional encoded color map (D). E. Fiber tract results showed left corticospinal tract (orange) was only partially involved.

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  Fig. 6 Diffusion weighted imaging and diffusion tensor imaging scans from stroke patient (66-year-old man with left extremity weakness). A, B. Axial diffusion weighted imaging (A) and apparent diffusion coefficient (B) showed small hyperintense lesion on right thalamus and internal capsule. Lesion volume was 2.86 cm3. C, D. Fiber tracts reconstructed in 3-dimensional space were superimposed on fractional anisotrophy map (C) and directional encoded color map (D). E. Fiber tract results revealed lesion was fully involved in right corticospinal tract (orange).

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