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

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 h and 6 h after embolization. Ten b values from 0 to 900 s/mm were 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 h and 6 h after embolization (P < 0.01 for all). No significant difference was observed in D* between the two sides at either time point (P = 0.086 and 0.336, respectively). In the stroke area, f at 6 h was significantly lower than that at 4.5 h (P = 0.016). A significantly positive correlation was detected between ADC and D in both stroke and contralateral sides at 4.5 h and 6 h (P < 0.001 for both). Significant correlation between ADC and f was only observed in the contralateral side at 4.5 h and 6 h (P = 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.