Korean J Radiol.  2005 Jun;6(2):75-81. 10.3348/kjr.2005.6.2.75.

Assessment of Tissue Viability Using Diffusion- and Perfusion-Weighted MRI in Hyperacute Stroke

• Moon WJ
• Na DG
• Ryoo JW
• Roh HG
• Byun HS
• Chon YH
• Chung EC

• KMID: 1783179
• DOI: http://doi.org/10.3348/kjr.2005.6.2.75

Abstract

OBJECTIVE
The aim of this study was to investigate the relationship between the diffusion and perfusion parameters in hyperacute infarction, and we wanted to determine the viability threshold for the ischemic penumbra using diffusion- and perfusion-weighted imaging (DWI and PWI, respectively). MATERIALS AND METHODS: Both DWI and PWI were performed within six hours from the onset of symptoms for 12 patients who had suffered from acute stroke. Three regions of interest (ROIs) were identified: ROI 1 was the initial lesion on DWI; ROI 2 was the DWI/PWI mismatch area (the penumbra) that progressed onward to the infarct; and ROI 3 was the mismatch area that recovered to normal on the follow-up scans. The ratios of apparent diffusion coefficient (ADC), the relative cerebral blood volume (rCBV), and the time to peak (TTP) were calculated as the lesions' ROIs divided by the contralateral mirror ROIs, and these values were then correlated with each other. The viability threshold was determined by using the receiver operating characteristic (ROC) curves. RESULTS: For all three ROIs, the ADC ratios had significant linear correlation with the TTP ratios (p < 0.001), but not with the rCBV ratios (p = 0.280). There was no significant difference for the ADC and rCBV ratios within the ROIs. The mean TTP ratio/TTP delay between the penumbras' two ROIs showed a significant statistical difference (p < 0.001). The cutoff value between ROI 2 and ROI 3, as the viability threshold, was a TTP ratio of 1.29 (with a sensitivity and specificity of 86% and 73%, respectively) and a TTP delay of 7.8 sec (with a sensitivity and specificity of 84% and 72%, respectively). CONCLUSION: Determining the viability thresholds for the TTP ratio/delay on the PWI may be helpful for selecting those patients who would benefit from the various therapeutic interventions that can be used during the acute phase of ischemic stroke.

Keyword

Brain, diffusion; Brain, infarction; Brain, MR; Brain, perfusion; Magnetic resonance (MR), diffusion study; Magnetic resonance (MR), perfusion study

MeSH Terms

Acute Disease
Aged
Cerebrovascular Accident/*diagnosis
Female
Humans
Magnetic Resonance Imaging/*methods
Male
Middle Aged
Sensitivity and Specificity
Tissue Survival/*physiology

Figure

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  Fig. 1 A 60-year-old man with a right-sided weakness, and he was initially imaged at 4.5 hours from the onset of stroke.

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  Fig. 2 A. The scatterplot showing the relationship between the apparent diffusion coefficient ratios and the time to peak ratios. The apparent diffusion coefficient ratios showed a weak negative correlation with the time to peak ratios (r2 = 0.092, F = 17.84, p < 0.001).B. The scatterplot showing the relationship between the apparent diffusion coefficient ratios and the cerebral blood volume ratios ratios. The apparent diffusion coefficient ratios showed no significant correlation with the relative cerebral blood volume ratios (r2 = 0.007, F = 1.17, p = 0.280).

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  Fig. 3 Box plots of the mean values of the lesion-contralateral normal regions' ratios for all the patients.

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