Quantitative assessment of hyperacute cerebral infarction with intravoxel incoherent motion MR imaging: Initial experience in a canine stroke model.

Abstract

PURPOSE: To evaluate the feasibility of intravoxel incoherent motion (IVIM) for the measurement of diffusion and perfusion parameters in hyperacute strokes. MATERIALS AND METHODS: An embolic ischemic model was established with an autologous thrombus in 20 beagles. IVIM imaging was performed on a 3.0 Tesla platform at 4.5&#x2009;h and 6&#x2009;h after embolization. Ten b values from 0 to 900 s/mmwere fitted with a bi-exponential model to extract perfusion fraction f, diffusion coefficient D, and pseudo-diffusion coefficient D*. Additionally, the apparent diffusion coefficient (ADC) was calculated using the mono-exponential model with all the b values. Statistical analysis was performed using the pairwise Student's t test and Pearson's correlation test. RESULTS: A significant decrease in f and D was observed in the ischemic area when compared with those in the contralateral side at 4.5&#x2009;h and 6&#x2009;h after embolization (P&#x2009;<&#x2009;0.01 for all). No significant difference was observed in D* between the two sides at either time point (P&#x2009;=&#x2009;0.086 and 0.336, respectively). In the stroke area, f at 6&#x2009;h was significantly lower than that at 4.5&#x2009;h (P&#x2009;=&#x2009;0.016). A significantly positive correlation was detected between ADC and D in both stroke and contralateral sides at 4.5&#x2009;h and 6&#x2009;h (P&#x2009;<&#x2009;0.001 for both). Significant correlation between ADC and f was only observed in the contralateral side at 4.5&#x2009;h and 6&#x2009;h (P&#x2009;=&#x2009;0.019 and 0.021, respectively). CONCLUSION: IVIM imaging could simultaneously evaluate the diffusion and microvascular perfusion characteristics in hyperacute strokes. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:550-556.