Resting State Regional Correlation Between FDG-PET and PCASL Perfusion MRI

Yoon Chung Kim¹, Yoon-Hee Cha¹, Shruthi Chakrapani¹, Danny JJ Wang¹

Perfusion is normally coupled to metabolism and neural function, and correlations of those for each brain region would be useful in interpreting future studies for investigating normal brain function or a diseased state. However, existing studies comparing ASL and FDG-PET are limited by small sample size. Thus, we performed a systematic evaluation of resting pseudo-continuous ASL (pCASL) and 18FDG-PET on 19 healthy subjects to determine the correlation between perfusion and FDG-PET CMRglu measurements across different brain regions. Our study showed that there is generally a good correlation between ASL CBF and PET CMRglu across pixels in the group mean images whereas the correlation of mean CBF and CMRglu values across 19 subjects is intermediate. We also found that metabolism of caudate and putamen is significantly higher relative to perfusion rate, consistent with an earlier report. While susceptibility effects and ROI size differences may to a certain degree account for the observed regional variations, the biophysical mechanism underlying the coupling and uncoupling of glucose metabolism and perfusion across brain regions warrants further investigation.