9.4 t horizontal bore magnet

Infarct size was assessed by means of magnetic resonance imaging (MRI). MRI studies were conducted on a 9.4-T horizontal bore magnet (Bruker BioSpin, Ettligen, Germany) with 12 cm wide actively shielded gradient coils (440 mT/m). Radiofrequency (RF) transmission was achieved with a birdcage volume redsonator; signal was detected using a four-element arrayed surface coil, positioned over the head of the animal, which was fixed with a teeth bar, earplugs and adhesive tape. Transmission and reception coils were actively decoupled from each other. Gradient-echo pilot scans were performed at the beginning of each imaging session for accurate positioning of the animal inside the magnet bore. Apparent diffusion coefficient (ADC) maps were acquired during MCA occlusion (80 min after the onset of ischemia) using a spin-echo echo-planar imaging sequence with the following acquisition parameters: field-of-view 19.2 × 19.2 mm², image matrix 128 × 128 (in-plane resolution 0.15 mm/pixel), 14 consecutive slices of 1 mm thickness, repetition time=4 s, echo time=30 ms and diffusion b values: 0, 100, 300, 600, 800, 1000 and 1400 s/mm². T2-weighted image was acquired 24 h and 7 days after the onset of ischemia. All images were processed and maps were constructed with ImageJ (Rasband WS, ImageJ, US National Institutes of Health, Bethesda, MD, USA, http://rsb.info.nih. gov/ij/, 1997–2009).