Regional Correlation between Resting State FDG PET and pCASL Perfusion MRI

Abstract

To determine how arterial spin labeling (ASL) measured perfusion relates to baseline metabolism, we compared resting state cerebral perfusion using pseudo-continuous ASL and cerebral glucose metabolism using (18)F-FDG PET in 20 normal volunteers. Greater regional metabolism relative to perfusion was observed in the putamen, orbitofrontal and temporal lobes, whereas perfusion was relatively higher in the hippocampus and insula. In a region of interest analysis limited to gray matter, the overall mean correlation between perfusion and metabolism across voxels was r=0.43 with considerable regional variability. Cross-voxel correlations between relative perfusion and metabolism in mean ASL and PET images of all 20 subjects were the highest in the striatum (caudate: r=0.78; putamen: r=0.81), and the lowest in medial temporal structures (amygdala: r=0.087; hippocampus: r=-0.26). Correlations between mean relative perfusion and metabolism across 20 subjects were the highest in the striatum (caudate: r=0.76; putamen: r=0.58), temporal lobe (r=0.59), and frontal lobe (r=0.52), but very poor in all other structures (r<0.3), particularly in caudal structures such as the hippocampus (r=-0.0026), amygdala (r=0.18), and insula (r=0.14). Although there was good overall correlation between perfusion and glucose metabolism, regional variability should be considered when using either ASL or (18)F-FDG PET as surrogate markers for neural activity.

Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: A PET/MR hybrid scanner study

“…Of note, a similar-530 ly limited degree of correlation has been found previously when testing 531 across-subjects correlations between imaging modalities of physiologi-532 cal functions that are known to be tightly coupled, like GU and CBF (e.g. 533Cha et al, 2013; Wong et al, 2006). Studies including both healthy 534 subjects under sensory or behavioural stimulation and patients with 535 pathologies characterized by reductions of cerebral glucose metabolism 536…”

A longitudinal characterization of perfusion in the aging brain and associations with cognition and neural structure

“…Because of neurovascular coupling, glucose consumption is tightly coupled with CBF (Baron et al, 1982;Furlow, Harrison, & Harrison, 1983), and [ 18 F]FDG-PET and [ 15 O]water PET are highly correlated (Bentourkia et al, 2000;Fox, Raichle, Mintun, & Dence, 1988). Furthermore, joint analyses of [ 18 F]FDG-PET and ASL acquisition have confirmed a good overall correlation between perfusion and glucose uptake in controls (Cha et al, 2013), as well as in patients with AD (Chen, Wolk, et al, 2011), Lewy body dementia (Nedelska et al, 2018), and frontotemporal dementia (Tosun et al, 2016). In ASL imaging, rather than using a radioactive tracer as a label, protons in the blood are labeled with a radiofrequency pulse; the perfusion of these magnetically-tagged protons to each voxel of the brain is then recorded.…”

Resting high‐frequency heart rate variability is related to resting brain perfusion

“…However, no studies to our awareness have provided consistent evidence for a relationship between resting cardiac vagal activity and resting cerebral blood flow—which presumably reflects resting metabolic activity linked to neural function (Ye et al, 2000; cf. Cha et al, 2013). The distinction between rest and reactivity is important insofar as resting cardiac vagal activity has been the predominant vagal index used in epidemiological studies linking short-term estimates of HRV with diverse health outcomes and end points, such as all-cause mortality, cardiovascular disease, and inflammation (Britton et al, 2007; Y. W. Chang et al, 2012; Habib, 1999; Huston & Tracey, 2011; Marsland et al, 2007; Thayer, Yamamoto, & Brosschot, 2010).…”