QUANTITATIVE MAGNETIC-RESONANCE-IMAGING OF PERFUSION USING MAGNETIC LABELING OF WATER PROTON SPINS WITHIN THE DETECTION SLICE

A technique for noninvasive quantitative magnetic resonance imaging of perfusion is presented. It relies on using endogenous water as a free ly diffusible tracer. Tissue water proton spins are magnetically label ed by slice-selective inversion, and longitudinal relaxation within th e slice is detected using a fast gradient echo magnetic resonance imag ing technique. Due to blood flow, nonexcited spins are washed into the slice resulting in an acceleration of the longitudinal relaxation pro cess, Incorporating this phenomenon into the Bloch equation yields an expression that allows quantification of perfusion on the basis of a s lice-selective and a nonselective inversion recovery experiment. Based on this technique, quantitative parameter maps of the regional cerebr al blood flow (rCBF) were obtained from eight rats. Evaluation of regi ons of interest within the cerebral hemispheres yielded an average rCB F value of 104 +/- 21 ml/min/100 g, which increased to 219 +/- 30 ml/m in/100 g during hypercapnia. The measured rCBF values are in good agre ement with previously reported literature values.