Intravoxel incoherent motion perfusion imaging in acute stroke: initial clinical experience.
BACKGROUND
Intravoxel incoherent motion (IVIM) imaging is an MRI perfusion technique that uses a diffusion-weighted sequence with multiple b values and a bi-compartmental signal model to measure the so-called pseudo-diffusion of blood caused by its passage through the microvascular network. The goal of the current study was to assess the feasibility of IVIM perfusion fraction imaging in patients with acute stroke.


METHODS
Images were collected in 17 patients with acute stroke. Exclusion criteria were onset of symptoms to imaging >5 days, hemorrhagic transformation, infratentorial lesions, small lesions <0.5 cm in minimal diameter and hemodynamic instability. IVIM imaging was performed at 3 T, using a standard spin-echo Stejskal-Tanner pulsed gradients diffusion-weighted sequence, using 16 b values from 0 to 900 s/mm(2). Image quality was assessed by two radiologists, and quantitative analysis was performed in regions of interest placed in the stroke area, defined by thresholding the apparent diffusion coefficient maps, as well as in the contralateral region.


RESULTS
IVIM perfusion fraction maps showed an area of decreased perfusion fraction f in the region of decreased apparent diffusion coefficient. Quantitative analysis showed a statistically significant decrease in both IVIM perfusion fraction f (0.026 ± 0.019 vs. 0.056 ± 0.025, p=2.2 · 10(-6)) and diffusion coefficient D compared with the contralateral side (3.9 ± 0.79 · 10(-4) vs. 7.5 ± 0.86 · 10(-4) mm(2)/s, p=1.3 · 10(-20)).


CONCLUSIONS
IVIM perfusion fraction imaging is feasible in acute stroke. IVIM perfusion fraction is significantly reduced in the visible infarct. Further studies should evaluate the potential for IVIM to predict clinical outcome and treatment response.
Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne, Rue du Bugnon 46, 1011, Lausanne, Switzerland, christian.federau@chuv.ch.
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Sumer
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Becce
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Maeder
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Wintermark
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002560:Cerebrovascular Circulation; D002675:Child, Preschool; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D020521:Stroke / Q000175:diagnosis*