BASE IMAGING - A NEW SPIN-LABELING TECHNIQUE FOR MEASURING ABSOLUTE PERFUSION CHANGES

A new technique for magnetic resonance imaging of absolute perfusion c hanges that uses magnetically labeled tissue water proton spins as a f reely diffusible tracer is described. It consists of unprepared basis (BA) images that serve as a reference and selective (SE) inversion pre pared images that are sensitive to perfusion changes. In the present s tudy, the BASE technique was applied to functional neuroimaging. BA an d SE images were alternatingly and repeatedly acquired during periods of visual stimulation and control, Visual stimulation was achieved wit h an alternating black/white checkerboard operating at a frequency of 8 Hz. Maps of the absolute cerebral blood flow changes (Delta CBF) wer e calculated from the image intensities of the corresponding BA and SE images, The individual mean values of Delta CBF measured in five heal thy volunteers ranged from 69 +/- 18 to 99 +/- 26 ml/min/100 g. Since the BASE technique does not require nonselective spin inversion, it ca n be used with small transmit/receive head coils (e.g., surface coils) . In addition, the BASE technique is robust against a mismatch of the inversion and detection slice profiles.