1. fMRI: Biological Basis and Experiment Design Lecture 15: CBF and Localization II CBF techniques Big veins and big voxels 1 light year = 5,913,000,000,000 miles?

2. Harrison, Harel et al., Cerebral Cortex 12:225 (2002) 100  m

3. Perfusion techniques FAIR – Flow-sensitive Alternating Inverstion Recovery MOTIVE – MOdulation of TIssue and VEssel signal QUIPSS – QUantitative Imaging of Perfusion using a Single Subtraction QUIPSS-II – QUIPSS... 2 nd version CASL – Continuous Arterial Spin Labeling PASL – Pulsed Arterial Spin Labeling

4. Perfusion (ASL) – general idea Water in blood is used as a tracer Two images are measured –With inversion of incoming blood Longitudinal magnetization of incoming blood is inverted, and subtracts from total voxel signal –Without inversion of incoming blood Difference image indicates

5. CASL vs. PASL Continuous ASL –long pulse is applied to neck arteries, so all blood coming into the head is inverted –After an appropriate delay (~1 – 2s) for that blood to get to the volume of interest, image is acquired –Reference image is taken without inversion pulse –Subtraction provides perfusion map Pulsed ASL –Inversion is done in slab surrounding slices of interest –The rest is the same...

7. Low res SE High res SE