Cortical spreading depression in the gyrencephalic feline brain studied bymagnetic resonance imaging

1. Time-lapse diffusion-weighted magnetic resonance imaging (DWI) was used to detect and characterize complex waves of cortical spreading depression ( CSD) evoked with KCl placed upon the suprasylvian gyrus of anaesthetized ca ts. 2. The time-lapse representations successfully demonstrated primary CSD wav es that propagated with elliptical wavefronts selectively over the ipsilate ral cerebral hemispheres with a velocity of 3.8 +/- 0.70 mm min(-1) (mean /- S.E.M. of 5 experiments). 3. In contrast, the succeeding secondary waves often remained within the or iginating gyrus, were slower (velocity 2.0 +/- 0.18 mm min(-1)), more fragm ented and varied in number. 4. Computed traces of the apparent diffusion coefficients (ADCs) showed neg ative deflections followed by monotonic decays (amplitudes: primary wave, - 19.9 +/- 2.8%; subsequent waves, -13.6 +/- 1.9%; duration at half-maximal d ecay, 150-200 s) when determined from regions of interest (ROIs) through wh ich both primary and succeeding CSD waves propagated. 5. The passage of both the primary and the succeeding waves often correlate d with transient DC potential deflections recorded from the suprasylvian gy rus. 6. The detailed waveforms of the ADC and the T-2*-weighted (blood oxygenati on level-dependent: BOLD) traces showed a clear reciprocal correlation. The se imaging features that reflect disturbances in cellular water balance agr ee closely with BOLD measurements that followed the propagation velocities of the first and subsequent CSD events. They also provide a close physiolog ical correlate for clinical observations of cortical Mood flow disturbances associated with human migraine.