Computer Methods and Programs in Biomedicine,
Год журнала:
2024,
Номер
257, С. 108433 - 108433
Опубликована: Сен. 24, 2024
Oxygen
is
carried
to
the
brain
by
blood
flow
through
generations
of
vessels
across
a
wide
range
length
scales.
This
multi-scale
nature
and
oxygen
transport
poses
challenges
on
investigating
mechanisms
underlying
both
healthy
pathological
states
imaging
techniques
alone.
Recently,
models
describing
whole
perfusion
have
been
developed.
Such
rely
effective
parameters
that
represent
microscopic
properties.
While
characterised,
those
for
are
still
lacking.
In
this
study,
we
set
quantify
associated
with
their
uncertainties.
bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2024,
Номер
unknown
Опубликована: Апрель 15, 2024
Abstract
Oxygen
is
carried
to
the
brain
by
blood
flow
through
generations
of
vessels
across
a
wide
range
length
scales.
This
multi-scale
nature
and
oxygen
transport
poses
challenges
on
investigating
mechanisms
underlying
both
healthy
pathological
states
imaging
techniques
alone.
Recently,
models
describing
whole
perfusion
have
been
developed.
Such
rely
effective
parameters
that
represent
microscopic
properties.
While
characterised,
those
for
are
still
lacking.
In
this
study,
we
set
quantify
associated
with
their
uncertainties.
We
first
present
multi-scale,
multi-compartment
model
based
porous
continuum
approach.
then
determine
values
parameters.
By
using
statistically
accurate
capillary
networks,
geometric
(vessel
volume
fraction
surface
area
ratio)
capture
microvascular
topologies
found
be
1.42%
627
[mm
2
/mm
3
],
respectively.
These
compare
well
obtained
from
human
monkey
vascular
samples.
addition,
maximum
consumption
rates
optimised
uniquely
define
distribution
over
depth.
Simulation
results
one-dimensional
tissue
column
show
qualitative
agreement
experimental
measurements
partial
pressure
in
rats.
highlight
importance
anatomical
accuracy
simulation
performed
within
patient-specific
mesh.
Finally,
one-at-a-time
sensitivity
analysis
reveals
not
sensitive
most
its
parameters;
however,
perturbations
solubilities
plasma
concentration
ratio
considerable
impact
oxygenation.
findings
demonstrate
validity
approach
organ-scale
draw
attention
significance
anatomy
certain
parameter
values.
bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2024,
Номер
unknown
Опубликована: Июль 23, 2024
Segments
in
the
arterial
network
have
a
>1000-fold
span
of
radii.
This
is
believed
to
result
from
adaptation
each
segment
wall
shear
stress
(WSS),
with
outward
respectively
inward
remodeling
if
WSS
higher
or
lower
than
some
reference
value.
While
this
seems
straightforward
mechanism
for
tree
design,
not
but
contains
numerous
arcades,
collaterals
and
other
looping
structures.
In
theoretical
study,
we
analyzed
stability
structures
networks
under
control.
Simulation
models
were
based
on
very
simple
topologies
as
well
published
human
coronary
mouse
cerebral
networks.
Adaptation
was
implemented
rate
change
structural
radius
that
proportional
deviation
its
WSS.
A
more
generalized
model
large
range
local
hemodynamic
stimuli,
including
velocity,
flow
power
dissipation.
For
over
12,000
tested
parameter
sets,
simulations
invariably
predicted
loss
loops
due
regression
one
segments.
small
networks,
case
both
model,
initial
conditions
parameters.
Loss
loopiness
also
by
included
direction-dependent
rates,
heterogeneous
rates
among
adapting
segments,
dynamic
conditions.
found
artery
subjected
mathematical
analysis
proved
direct
consequence
Kirchhoff's
circuit
law,
which
loop
leads
positive
eigenvalue
Jacobian
matrix
partial
derivatives
therefore
unstable
equilibria
presence
loops.
an
inherent
property
adapt
hemodynamics.
Additional
mechanisms
are
needed
explain
their
presence,
communication
between
connected
PLoS Computational Biology,
Год журнала:
2024,
Номер
20(5), С. e1011973 - e1011973
Опубликована: Май 23, 2024
Recent
progresses
in
intravital
imaging
have
enabled
highly-resolved
measurements
of
periarteriolar
oxygen
gradients
(POGs)
within
the
brain
parenchyma.
POGs
are
increasingly
used
as
proxies
to
estimate
local
baseline
consumption,
which
is
a
hallmark
cell
activity.
However,
profile
around
given
arteriole
arises
from
an
interplay
between
consumption
and
delivery,
not
only
by
this
but
also
distant
capillaries.
Integrating
such
interactions
across
scales
while
accounting
for
complex
architecture
microvascular
network
remains
challenge
modelling
perspective.
This
limits
our
ability
interpret
experimental
maps
constitutes
key
bottleneck
toward
inverse
determination
metabolic
rates
oxygen.
We
revisit
problem
parenchymal
transport
metabolism
introduce
simple,
conservative,
accurate
scalable
direct
numerical
method
going
beyond
canonical
Krogh-type
models
their
associated
geometrical
simplifications.
focus
on
two-dimensional
formulation,
concepts
needed
combine
operator-splitting
Green’s
function
approach.
Oxygen
concentration
decomposed
into
slowly-varying
contribution,
discretized
Finite
Volumes
over
coarse
cartesian
grid,
rapidly-varying
approximated
analytically
grid-cells
surrounding
each
vessel.
Starting
with
simple
test
cases,
we
thoroughly
analyze
resulting
errors
comparison
simulations
original
problem,
showing
considerable
improvement
computational-cost/accuracy
balance
compared
previous
work.
then
demonstrate
model
flexibly
generate
synthetic
data
reproducing
spatial
dynamics
parenchyma,
sub-grid
resolution.
Based
these
data,
show
that
capillaries
cannot
be
overlooked
when
interpreting
POGs,
thus
reconciling
recent
cortical
layers
fundamental
idea
variations
vascular
density
depth
cortex
may
reveal
underlying
differences
neuronal
organization
load.
Computer Methods and Programs in Biomedicine,
Год журнала:
2024,
Номер
257, С. 108433 - 108433
Опубликована: Сен. 24, 2024
Oxygen
is
carried
to
the
brain
by
blood
flow
through
generations
of
vessels
across
a
wide
range
length
scales.
This
multi-scale
nature
and
oxygen
transport
poses
challenges
on
investigating
mechanisms
underlying
both
healthy
pathological
states
imaging
techniques
alone.
Recently,
models
describing
whole
perfusion
have
been
developed.
Such
rely
effective
parameters
that
represent
microscopic
properties.
While
characterised,
those
for
are
still
lacking.
In
this
study,
we
set
quantify
associated
with
their
uncertainties.