Intravoxel incoherent motion diffusion-weighted imaging in stroke patients: initial clinical experience

To evaluate the feasibility of using intravoxel incoherent motion (IVIM) to measure diffusion and perfusion parameter variations in stroke.

Thirty-eight stroke patients were enrolled in the study. IVIM imaging was performed using 15 b-values from 0 to 1000 s/mm(2). Arterial spin labelling (ASL) magnetic resonance perfusion was also undertaken. Relations between the IVIM parameters (including apparent diffusion coefficient [ADC], diffusion coefficient Dslow [D], pseudo-diffusion coefficient Dfast [D*], fractional perfusion-related volume [f]) and fD* (the multiplication of the first two parameters) and the ASL-derived parameter, cerebral blood flow (CBF), were analysed using paired t-tests. Comparisons of all the parameters between lesions and contralateral normal regions, as well as between acute and subacute groups were analysed using Student's t-test.

There were positive correlations between f and CBF as well as fD* and CBF (r=0.472 and 0.653). Quantitative analysis showed a significant decrease in ADC, D, D*, f, fD*, and CBF of the lesions compared with the contralateral side, in which the decrease of fD* (68.6%) was highest. The values of ADC, f, and fD* increased in the subacute period group compared with the acute period group.

IVIM analysis allowed separation of perfusion contribution from true diffusion and thus provided an evaluation of the perfusion and diffusion variations during stroke, which might further elucidate the mechanisms of ischaemic stroke.