Comparison of Cerebral Blood Flow Acquired by Simultaneous [¹⁵O]Water Positron Emission Tomography and Arterial Spin Labeling Magnetic Resonance Imaging

Abstract

Until recently, no direct comparison between [15O]water positron emission tomography (PET) and arterial spin labeling (ASL) for measuring cerebral blood flow (CBF) was possible. With the introduction of integrated, hybrid magnetic resonance (MR)-PET scanners, such a comparison becomes feasible. This study presents results of CBF measurements recorded simultaneously with [15O]water and ASL. A 3T MR-BrainPET scanner was used for the simultaneous acquisition of pseudo-continuous ASL (pCASL) magnetic resonance imaging (MRI) and [15O]water PET. Quantitative CBF values were compared in 10 young healthy male volunteers at baseline conditions. A statistically significant (P<0.05) correlation was observed between the two modalities; the whole-brain CBF values determined with PET and pCASL were 43.3±6.1 mL and 51.9±7.1 mL per 100 g per minute, respectively. The gray/white matter (GM/WM) ratio of CBF was 3.0 for PET and 3.4 for pCASL. A paired t-test revealed differences in regional CBF between ASL and PET with higher ASL-CBF than PET-CBF values in cortical areas. Using an integrated, hybrid MR-PET a direct simultaneous comparison between ASL and [15O]water PET became possible for the first time so that temporal, physiologic, and functional variations were avoided. Regional and individual differences were found despite the overall similarity between ASL and PET, requiring further detailed investigations.

Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-Labeling in Healthy Volunteers

“…Other studies have found moderate to good correlations (r ϭ 0.4 -0.8) between pseudocontinuous ASL and PET imaging for pCBF measurements. 4,27,28 On the contrary, Henriksen et al 29 showed a large underestimation of ASLbased pCBF (75%) compared with the estimation by PCMRI and no correlation between the 2 methods. One explanation for this result might be that they used a model-free pulsed-ASL method.…”

Quantifying fluctuations of resting state networks using arterial spin labeling perfusion MRI

“…[37][38][39] Such reference image acquisition can and will be included in future studies. Since the average gray matter perfusion is approximately 70 ml/100g/min for normal healthy young volunteers, 40 the absolute perfusion signal fluctuations can be estimated from this population average and the reported signal fluctuation percentage in this paper. An additional benefit of ASL for study of resting state networks is the reduction of non-neural noise sources observed with BOLD.…”

Baseline brain perfusion and brain structure in patients with major depression: a multimodal magnetic resonance imaging study

“…53 Also, in neuropsychiatric diseases such as Alzheimer disease, ASL and FDG-PET have been shown to detect similar, but not identical, perfusion/metabolism abnormalities, 50,51 suggesting complementary and nonredundant information provided by both imaging modalities. Modality-dependent characteristics, however, cannot fully account for our finding of lower rCBF in the subgenual part of the ACC.…”