Comparison of global cerebral blood flow measured by phase‐contrast mapping MRI with ¹⁵O‐H₂O positron emission tomography

Abstract

PurposeTo compare mean global cerebral blood flow (CBF) measured by phase‐contrast mapping magnetic resonance imaging (PCM MRI) and by 15O‐H2O positron emission tomography (PET) in healthy subjects. PCM MRI is increasingly being used to measure mean global CBF, but has not been validated in vivo against an accepted reference technique.Materials and MethodsSame‐day measurements of CBF by 15O‐H2O PET and subsequently by PCM MRI were performed on 22 healthy young male volunteers. Global CBF by PET was determined by applying a one‐tissue compartment model with measurement of the arterial input function. Flow was measured in the internal carotid and vertebral arteries by a noncardiac triggered PCM MRI sequence at 3T. The measured flow was normalized to total brain weight determined from a volume‐segmented 3D T 1‐weighted anatomical MR‐scan.ResultsMean CBF was 34.9 ± 3.4 mL/100 g/min measured by 15O‐H2O PET and 57.0 ± 6.8 mL/100 g/min measured by PCM MRI. The measurements were highly correlated (P = 0.0008, R2 = 0.44), although values obtained by PCM MRI were higher compared to 15O‐H2O PET (absolute and relative differences were 22.0 ± 5.2 mL/100 g/min and 63.4 ± 14.8%, respectively).ConclusionThis study confirms the use of PCM MRI for quantification of global CBF, but also that PCM MRI systematically yields higher values relative to 15O‐H2O PET, probably related to methodological bias. Level of Evidence: 3J. Magn. Reson. Imaging 2017;45:692–699.

A Noninvasive Method for Quantifying Cerebral Blood Flow by Hybrid PET/MRI

“…Lastly, velocity encoding was set to 80 cm/s (24) in order to measure both low and high flows at hypo-and hypercapnia, respectively. A recent study comparing CBF measurements from PC MRI and 15 O-water PET in healthy human subjects reported only a moderate correlation between the 2 techniques and significantly higher values from PC MRI-up to a 63% overestimation (38). This result is in contrast to the current study, in which a strong correlation was found (slope, 0.88; intercept, 1.7 mL/100 g/min; R 2 5 0.9 [ Fig.…”

Robust cerebrovascular blood velocity and flow rate estimation from 4D‐CTA

“…Furthermore, the 4D-CTA flow rates indicate an average global cerebral blood flow (CBF) of 545 AE 78 ml/min. This is in good agreement with a recent PET study (503 ml/min), 27 which also pointed out discrepancies with PCMRI data neglecting partial volume effects.…”

3D phase contrast MRI: Partial volume correction for robust blood flow quantification in small intracranial vessels

“…Similarly, comparisons with cerebral blood flow rate (CBF) assessed with positron emission tomography (PET) in Ref. showed recurrent overestimation of 2D‐PCMRI measurements. These results emphasize the importance to correct these biases independently of the spatial resolution.…”

“…Mainly tested on 2D‐PCMRI datasets, these post‐processings require the localization of the circulating volume or assume idealized velocity profiles (typically parabolic Poiseuille flow) which are in general erroneous. Previous in vitro and recent in vivo studies have shown that these partial volume effects might lead to blood flow rate overestimation. However, these effects were not considered in most of the recent intracranial flow investigations .…”