On the Validation of a Multiple-Network Poroelastic Model Using Arterial Spin Labeling MRI Data

Abstract

The Multiple-Network Poroelastic Theory (MPET) is a numerical model to characterize the transport of multiple fluid networks in the brain, which overcomes the problem of conducting separate analyses on individual fluid compartments and losing the interactions between tissue and fluids, in addition to the interaction between the different fluids themselves. In this paper, the blood perfusion results from MPET modeling are partially validated using cerebral blood flow (CBF) data obtained from arterial spin labeling (ASL) magnetic resonance imaging (MRI), which uses arterial blood water as an endogenous tracer to measure CBF. Two subjects—one healthy control and one patient with unilateral middle cerebral artery (MCA) stenosis are included in the validation test. The comparison shows several similarities between CBF data from ASL and blood perfusion results from MPET modeling, such as higher blood perfusion in the gray matter than in the white matter, higher perfusion in the periventricular region for both the healthy control and the patient, and asymmetric distribution of blood perfusion for the patient. Although the partial validation is mainly conducted in a qualitative way, it is one important step toward the full validation of the MPET model, which has the potential to be used as a testing bed for hypotheses and new theories in neuroscience research.

Exploring neurodegenerative disorders using a novel integrated model of cerebral transport: Initial results

“… Values of shear modulus, G , and Lamé’s constant λ for the white matter (with subscript w ) than the grey matter (with subscript g ) are given. The reader is referred to Vardakis et al, Guo et al and Chou 3 , 47 , 48 , 54 – 56 for further details. SSBF: subject-specific blood flow profile derived arterial pressure.…”

“…In previous work, the authors conducted grid-independence studies, verified the multiporoelastic system against analytical solutions, 47 , 57 , 58 in addition to the system being recently validated with respect to data arising from both a CSF infusion test 54 and ASL based values. 55 …”

“…In line with previous work, grid-independence of the 6-MPET system was conducted, and converged solutions fell within a specified percentage band of numerical error estimates. For details regarding the discretisation of the conservation equations, the reader is referred to Guo et al and Vardakis et al 47 , 48 , 54 , 55 Finally, the discretised form of the 6-MPET system is solved using the PETSc library. 59 , 60 …”

“…Additionally, the permeability of the arteriole/capillary compartment is assigned partitioned values for white (k c,white ) and grey matter (k c,grey ), and reflects the calibration of the capillary compartment with respect to the validation of the filtration velocity via CBF data acquired from ASL images. 55 In this manuscript, a new set of Biot-Willis constants were used, reflecting the theoretical nature of this study. In previous studies (see Vardakis et al.…”

Study protocol of validating a numerical model to assess the blood flow in the circle of Willis

“…Cerebral perfusion can be simulated from the level of major cerebral arteries by lumped model 6 to the level of microvascular circulation in the grey and white matter by multiple-network pro-elastic models. 7 In addition, threedimensional models can simulate haemodynamic parameters, such as wall shear stress and oscillating shear stress, [8][9][10] as well as that it can predict the haemodynamic situation after a change in arterial network structure. 11 12 Currently, the application of numerical models is mainly restricted to a laboratory setting, because of its complicated input and simulation, but also due to insufficient validation for use in clinical practice, since many haemodynamic parameters cannot be measured in vivo.…”