Distribution of intravoxel incoherent motion MRI-related parameters in the brain: evidence of interhemispheric asymmetry.

AIM: To compare intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI)-derived true diffusion (D) and perfusion fraction (f)-values of the two hemispheres to detect the presence of asymmetrical differences.

MATERIALS AND METHODS: Forty-seven healthy right-handed volunteers were assessed using IVIM imaging. The interhemispheric D- and f-values were compared using paired t-tests and two related-samples Wilcoxon's test.

RESULTS: Comparison of the interhemispheric D- and f-values of the grey matter revealed a significant difference in the D-value of the frontal lobe and the f-value of the temporal lobe (p=0.028, p=0.030, respectively). A significant difference in the D-values of the frontal, temporal, and occipital lobes (p=0.003, p=0.005, and p=0.001, respectively) was seen, whereas no significant difference in f-values was seen.

CONCLUSIONS: The distribution of the IVIM-derived D- and f-values in the two hemispheres was not completely symmetrical. Radiologists should consider this difference when the contralateral region is used as internal reference to normalise the IVIM imaging results. Average values of the interhemispheric white matter within the same lobe as the lesion may be the best internal reference.