Tomographic-cephalometric evaluation of the pars petrosa of temporal bone as sexing method

Abstract

This study assesses a common issue in Forensic Anthropology: sex determination in fragmented or incomplete human skeletal remains. Previous studies have reported a significant sexual dimorphism in adult individuals for the lateral angle and acoustic pore of the pars petrosa of temporal bone. Our aim is to test the usefulness of pars petrosa as method for estimating sex using standardized CT axial images and cephalometric techniques. We evaluate four cephalometric markers of the pars petrosa (lateral angle, acoustic pore diameter, the divergence of the medial-posterior and medial-anterior segments, and a proposed angle named “Cephalometric Angle of pars petrosa”) in 150 adult individuals of known sex and age treated in the Hospital da Beneficência Portuguesa (São Paulo, Brazil). Discriminant analysis using these four parameters allows correct sex classification in 72% of individuals, however, the Cephalometric Angle, individually, reaches 74% of correct classifications. Our results suggest that tomographic-cephalometric evaluation of the pars petrosa of temporal bone can be employed as indicial method for differentiating sex in some contexts.

Full text

Forensic
Anthropology
Tomographic-cephalometric
evaluation
of
the
pars
petrosa
of
temporal
bone
as
sexing
method
L.N.
Pezo-Lanfranco
a,
*,
R.G.
Haetinger
b,c
a
Laboratório
de
Antropologia
Biológica,
Instituto
de
Biociências
da
Universidade
de
São
Paulo,
Rua
do
Matão
277,
05508-090,
Cidade
Universitária,
São
Paulo,
SP,
Brazil
b
Med
Imagem–BP
Medicina
Diagnóstica,
Hospital
Beneficência
Portuguesa
de
São
Paulo,
São
Paulo,
SP,
Brazil
c
Departamento
de
Anatomia,
Instituto
de
Ciências
Biomédicas
da
Universidade
de
São
Paulo,
Av.
Prof.
Lineu
Prestes
2415,
05508-900,
Cidade
Universitária,
São
Paulo,
SP,
Brazil
A
B
S
T
R
A
C
T
This
study
assesses
a
common
issue
in
Forensic
Anthropology:
sex
determination
in
fragmented
or
incomplete
human
skeletal
remains.
Previous
studies
have
reported
a
significant
sexual
dimorphism
in
adult
individuals
for
the
lateral
angle
and
acoustic
pore
of
the
pars
petrosa
of
temporal
bone.
Our
aim
is
to
test
the
usefulness
of
pars
petrosa
as
method
for
estimating
sex
using
standardized
CT
axial
images
and
cephalometric
techniques.
We
evaluate
four
cephalometric
markers
of
the
pars
petrosa
(lateral
angle,
acoustic
pore
diameter,
the
divergence
of
the
medial-
posterior
and
medial-anterior
segments,
and
a
proposed
angle
named
“Cephalometric
Angle
of
pars
petrosa”)
in
150
adult
individuals
of
known
sex
and
age
treated
in
the
Hospital
Beneficência
Portuguesa
(São
Paulo,
Brazil).
Discriminant
analysis
using
these
four
parameters
allows
correct
sex
classification
in
72
%
of
individuals,
however,
the
Cephalometric
Angle,
individually,
reaches
74
%
of
correct
classifications.
Our
results
suggest
that
tomographic-
cephalometric
evaluation
of
the
pars
petrosa
of
temporal
bone
can
be
employed
as
indicial
method
for
differentiating
sex
in
some
contexts.
A
R
T
I
C
L
E
I
N
F
O
Keywords:
Lateral
angle
Forensic
anthropology
Internal
acoustic
canal
Sexual
dimorphism
Human
identification
1.
Introduction
The
determination
of
sex
in
skeletal
human
remains,
based
on
the
recognition
of
dimorphic
anatomical
traits
of
the
pelvic
bones
and
skull,
is
a
standardized
procedure
of
wide
application
in
physical
and
forensic
anthropology
[1,2].
However,
human
bones
are
not
always
well-
preserved
and
forensic-anthropologists
are
compelled
to
work
with
fragmented,
cremated
or
taphonomically
altered
bones
(i.e.,
environ-
mental
factors,
burial
conditions,
mass
disasters,
time),
which
represents
a
serious
problem
in
Forensic
Anthropology
when
the
identification
of
individuals
is
imperative.
The
search
for
alternative
methods
on
sex
determination
in
skeletonized
individuals
has
guided
the
study
of
sexual
dimorphism
in
various
anatomical
traits.
The
pars
petrosa
ossis
temporalis,
a
compact
structure
that
houses
the
internal
organs
of
the
auditory
system,
has
been
part
of
these
attempts.
Due
to
its
density
and
robustness,
pars
petrosa
is
often
the
only
bone
that
survives
integrally
to
the
effects
of
disasters,
cremation,
or
long
burial
periods,
so
it
has
great
informative
potential
from
a
forensic
viewpoint
[3–6].
Several
anatomical
features
of
the
pars
petrosa
have
reported
significant
sexual
dimorphism
[3,7–12].
Among
them,
the
diameter
of
the
acoustic
pore
[9]
and
the
course
of
the
meatus
acusticus
internus
[10,8–12]
have
been
tested
as
methods
of
sex
discrimination.
The
“lateral
angle”
(LA)
denotes,
in
cross-section,
the
inclination
of
the
internal
acoustic
canal
(which
contains
the
vestibulocochlear
and
facial
nerves)
relative
to
the
medial
surface
of
the
pars
petrosa.
The
pioneering
method
of
the
LA
measurement
was
developed
by
Wahl
[10]
in
a
forensic
sample
of
70
individuals
using
negative
casts
(replicas)
of
the
meatus
acusticus
internus
obtained
using
clay
as
impression
material.
Prior
sectioning
of
the
replica
with
a
scalpel,
he
measures
LA,
the
acute
angle
formed
by
the
surface
of
the
medial
facies
of
the
petrous
bone
and
the
anterior
wall
of
the
meatus
acusticus
internus,
with
an
angle
protractor.
This
research
concluded
that
LA
measurements
equal
to
or
greater
than
45were
more
frequent
in
females.
Further
research
using
silicone
replicas
in
forensic
samples
of
known
sex
[5,6,11–13]
confirmed
that
mean
values
of
LA
differed
in
approxi-
mately
10between
sexes
(39.4in
males;
48.3in
females;
p
<
0.001
[11]).
None
of
these
studies
accused
significant
side
differences,
so
either
sidecouldbeusedforsexdiscrimination.
Thesestudiesalso showed
thatthe
number
of
correctly
classified
individuals
varied
between
63
%
and
83.2
%
[5,6,11–13].
Considering
the
relative
technical
difficulties
of
obtaining
reliable
measurements
from
silicone
replicas
[5,13,14],
the
use
of
multislice
computed
tomography
(MSCT)
in
the
evaluation
of
LA
was
introduced.
*
Corresponding
author.
E-mail
address:
luispezolanfranco@usp.br
(L.N.
Pezo-Lanfranco).
http://doi.org/10.1016/j.fsir.2021.100174
Received
2
November
2020;
Received
in
revised
form
11
January
2021;
Accepted
13
January
2021
Available
online
19
January
2021
2665-9107/©
2021
The
Author(s).
Published
by
Elsevier
B.V.
This
is
an
open
access
article
under
the
CC
BY
license
(http://creativecommons.org/licenses/by/4.0/).
Forensic
Science
International:
Reports
3
(2021)
100174
Contents
lists
available
at
ScienceDirect
Forensic
Science
International:
Reports
jo
u
r
nal
h
o
mep
ag
e:
ww
w.els
evier
.c
om
/lo
cat
e/fs
ir

Akansel
et
al.
[15]
evaluated
92
individuals
(47
women
and
45
men
of
Turkish
origin)
using
a
measurement
technique
modified
from
skeletal
studies
[11]
and
concluded
that
the
mean
LA
was
higher
in
women
(F
=
45.5
7.18;
M
=
41.6
6.78;
significant
p
<
0.01),
also
demonstrating
that
CT
was
able
to
replicate
the
results
obtained
using
casts.
Although
it
was
not
possible
to
obtain
a
single
cutoff
value
to
discriminate
sex,
LA
values
35were
93.6
%
specific
for
males
and
LA
values
60were
97.7
%
specific
for
females.
However,
other
studies
using
CT
have
shown
opposite
results
[16–18]
reporting
non-significant
differences
between
sexes
(46.5in
females
and
43.4in
males),
considerable
overlap
of
values,
and
poor
classification
performance
(correct
sexing
approximately
56
%,
on
average);
categorizing
the
method
as
“non-conclusive”
for
sex
determination.
The
diameter
of
the
internal
acoustic
pore
(PA),
another
trait
of
the
temporal
bone
tested
to
differentiate
sex,
was
examined
by
Lynnerup
et
al.
[9]
in
113
known-sex
skeletons
by
introducing
drills
calibrated
in
millimeters
(diameters
of
1.0–10.0
mm,
with
an
increase
of
0.5
mm),
finding
a
mean
difference
of
approximately
0.3
mm
(mean
diameter
of
3.7
mm
in
males
and
3.4
mm
in
females;
significant
p
<
0.009).
This
study
concluded
that
a
diameter
of
2.5
mm
can
be
classified
as
female
and
a
diameter
of
4.0–4.5
mm
as
male.
The
tests
of
correct
sex
classification
using
a
cutoff
point
(<3.0
mm
=
female;
>3.5
mm
=
male)
reach
70
%.
CT
studies
have
shown
lower
values
of
correct
sex
classification
than
those
observed
in
dry
bones.
These
inconsistencies
are
possibly
related
to
methodological
issues
(i.e.,
sample
size,
asymmetry
between
sexes,
ancestry
differences,
sampling
techniques)
that
would
be
better
evaluated
in
“controlled”
samples.
Until
now,
all
studies
on
LA
and
AP
were
conducted
in
populations
characterized
by
relatively
low
phenotypic
variability
[19]
such
as
Scandinavian
[9,11],
Central
[3,10,12,14,17]
and
Southern
[5,6,13]
European,
and
Turkish
[15,18].
Thus,
their
results
may
be
inadequate
to
be
interpolated
to
more
heterogeneous
or
miscegenated
populations.
Although
the
discriminatory
potential
of
LA
and
AP
for
sexing
is
relatively
limited
when
applied
independently,
the
combination
of
both
with
other
potentially
dimorphic
traits
of
the
pars
petrosa
using
multivariate
statistics
can
improve
the
method
and
make
it
applicable
to
the
resolution
of
forensic
cases,
especially
in
contexts
of
considerable
bone
fragmentation
or
lack
of
viable
DNA
(4,19).
Considering
the
advantages
that
CT
images
provide,
in
this
research
we
explore
the
potential
of
new
cephalometric
tracing
for
sex
discrimination.
After
preliminary
explorations
of
the
pars
petrosa
we
notice
a
slight
morphological
difference
between
males
and
females
in
the
convexity
or
bending
the
medial
surface
of
pars
petrosa.
Accordingly,
the
medial
surface
in
males
is
commonly
straighter
in
the
anteroposterior
direction,
while
in
women
it
has
a
more
convex
or
irregular
shape.
This
observation
led
us
to
explore
the
levels
of
divergence
between
the
anterior
and
posterior
segments
of
the
medial
facies
(using
the
acoustic
pore
as
reference),
introducing
two
angular
measurements.
The
first,
called
Medial-surface
Inflection
Angle
of
the
pars
petrosa
(MIA),
which
characterizes
the
bending
degree
of
the
pars
petrosa
between
its
anterior
(spheno-petrous)
and
posterior
(tympanic-petrous)
segments.
The
second,
a
cephalometric
tracing
called
Cephalometric
Angle
of
pars
petrosa
(CAPP),
that
shows
the
degree
of
divergence
between
the
anterior
and
posterior
segments
relative
to
the
internal
acoustic
canal
direction.
Fig.
1.
Landmark
points
for
the
recording
of
the
four
cephalometric
measurements
of
the
pars
petrosa
ossis
temporalis
used
in
this
work.
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
2

This
study
evaluates
the
performance
of
these
four
parameters
for
the
determination
of
sex
using
CT
axial
images
of
living
individuals
from
a
multiethnic
sample
(Brazilians).
First,
we
describe
the
parameters
in
males
and
females.
Next,
we
assess
their
reliability
(repeatability,
replicability,
and
accuracy),
and
finally,
we
test
their
discriminatory
potential.
2.
Material
and
methods
2.1.
Sample
and
inclusion
criteria
The
sample
consisted
of
150
adult
individuals
of
known
sex
(M
=
75;
F
=
75),
aged
between
19
and
89
years
(M:
x
=
49.19
s
=
18.2;
F:
x
=
46.95
s
=
14.4;
p
=
0.405),
which
had
CT
studies
of
temporal
bones
indicated
for
the
diagnosis
of
otological
or
neurological
diseases,
attended
in
the
radiology
unit
(Med
Imagem
-
BP
Medicina
Diagnóstica)
of
the
Hospital
Beneficência
Portuguesa
(São
Paulo,
Brazil).
Individuals
with
congenital
or
developmental
ear
anomalies,
temporal
bone
fractures,
post-surgical
alterations
or
neoplasms,
and
CT
technically
inadequate
[11]
were
excluded.
The
images
were
acquired
with
Somatom
Flash
(dual
source,
256),
Somatom
AS
Definition
Plus
(128),
and
Somatom
Perspective
(128)
Siemens
CT
scanners.
Axial
images
were
recorded
according
to
the
following
parameters:
120140
kV,
100297
mA,
slice
thickness
0.52
mm
standardized
between
WW
3600–4400
D
and
WL
=
360–400,
reconstruction
filter
H60
sharp
for
bone.
2.2.
Recording
methods
2.2.1.
Image
selection
The
proposed
cephalometric
parameters
were
measured
in
the
same
tomographic
image
of
the
temporal
bone,
so
this
is
a
crucial
step
for
the
application
of
the
method.
For
the
selection
of
the
most
appropriate
image
(tomographic
slice)
a
method
adapted
from
Akansel
et
al.
[15:
94,
98],
was
used.
They
used
the
CT
image
slice
in
which
the
apex
of
the
internal
acoustic
canal
(fundus)
appears
more
pointed
(selected
from
the
slices
that
clearly
showed
the
meatus)
with
the
individual
oriented
trans-
versally
to
the
canthomeatal
line.
The
selected
image
should
show
the
following
anatomical
structures:
1)
internal
acoustic
canal;
2)
the
transverse
or
lateral
semicircular
canal;
3)
the
opening
of
the
facial
nerve
canal
or
Fallopian
canal
(in
the
slice
of
maximum
permeability);
4)
the
sphenopetrosal
synchondrosis,
and
5)
the
sigmoid
sinus
of
the
occipital
bone
(Fig.
1).
For
most
cases,
this
was
the
upper
slice
closest
to
the
one
that
presented
the
incudomalleal
joint
more
clearly
(ice
cream
in
cone)
[15].
In
some
cases,
not
all
anatomical
structures
appeared
in
the
same
slice,
so,
the
image
showing
the
facial
nerve
canal
and
the
greatest
number
of
anatomical
structures
was
selected.
2.2.2.
Linear
and
angular
measurements
In
a
pilot
study,
6
angular
measurements
of
the
pars
petrosa
and
3
linear
measurements
of
the
internal
acoustic
canal
were
examined.
Only
4
parameters
were
selected,
three
angles
(measured
in
sexagesimal
degrees):
1)
Lateral
Angle
-
LA;
2)
Medial-surface
inflection
angle
-
MIA;
3)
Cephalometric
angle
of
the
pars
petrosa
-
CAPP;
and
one
linear
measurement
(in
mm):
4)
Acoustic
Pore
Diameter
-
AP.
A
total
of
9
landmarks
and
5
lines
were
drawn
on
the
selected
image
(Table
1
and
Fig.
1).
The
parameters
were
measured,
as
described
in
Table
2
and
Fig.
2,
in
a
blind
test
using
the
“length”
and
“angle”
tools
of
the
RadiAnt
DICOM
Viewer
3.02
software.
2.2.3.
Statistical
analysis
The
four
parameters
were
submitted
to
descriptive
analysis
(determination
of
mean,
maximum
and
minimum
values,
standard
deviation,
and
outliers)
according
to
sex.
After
exploratory
analysis
(Kolgomorov-Smirnov
and
Levene’s
tests,
Tables
S1
and
S2,
respectively),
intergroup
differences
were
examined
with
t-test
for
independent
samples
and
Mann-Whitney
U
test
at
p
<
0.05.
In
order
to
explore
differences
between
right
and
left
side,
the
values
of
the
four
parameters
were
Table
1
Landmarks
and
lines
for
cephalometric
tracing
of
the
pars
petrosa.
Landmark
points
Point
A
Maximum
curvature
point
between
the
anterior
wall
of
the
internal
acoustic
canal
and
the
medial-anterior
surface
of
the
pars
petrosa.
In
the
image,
that
is
the
most
concave
point
in
the
curvature
of
the
anterior
rim
of
the
acoustic
pore.
Point
B
Maximum
curvature
point
between
the
posterior
wall
of
the
internal
acoustic
canal
and
the
medial-posterior
surface
of
the
pars
petrosa.
In
the
image,
that
is
the
most
concave
point
in
the
curvature
of
the
posterior
rim
of
the
acoustic
pore.
Point
C
The
most
prominent
point
of
the
medial-posterior
surface
of
the
pars
petrosa.
If
there
are
two
or
more
prominences,
the
most
pronounced
should
be
considered.
If
they
have
approximately
the
same
size,
the
point
located
closer
to
the
acoustic
pore
should
be
considered.
Point
D
Point
D
is
located
on
the
external
cortical
of
the
medial-posterior
surface
of
the
pars
petrosa,
which
coincides
with
the
septum
or
bony
prominence
of
the
sigmoid
sinus
from
the
occipital
bone.
Point
D’
Point
D’
is
located
on
the
external
cortical
of
the
medial-posterior
surface
of
the
pars
petrosa,
which
coincides
with
the
boundary
between
the
compact
bone
(roughly
at
the
projection
of
a
90line
tangent
to
the
transverse
semicircular
canal)
and
the
mastoid
cells.
Point
SP
The
more
outer
point
of
the
sphenopetrosal
synchondrosis
of
the
pars
petrosa
exposed
in
the
image.
Point
F
The
middle
point
of
the
opening
of
the
facial
nerve
or
Fallopian
canal.
Point
M
The
middle
point
of
the
line
A–B.
Point
M’
Point
in
the
projection
of
the
line
F–M
at
the
intersection
of
the
Basal
and
Pendular
lines.
Reference
Lines
Line
1
The
line
between
the
points
SP
and
A
and
its
projection.
Represents
the
inclination
of
the
medial-anterior
surface
of
pars
petrosa
(Apex
partis
petrosae).
Line
2
The
line
between
the
points
C
and
D
and
its
projection.
Represents
the
inclination
of
the
medial-posterior
surface
of
pars
petrosa
(Facies
posterior
partis
petrosae).
Line
3
The
line
between
the
points
C
and
D’
and
its
projection.
It
is
also
called
the
Basal
line.
Line
4
The
line
between
the
point
SP
and
the
point
of
intersection
of
the
Basal
and
F-M’
lines.
It
is
also
called
the
Pendular
line.
Line
F-
M’
The
line
between
the
opening
of
the
facial
nerve
(point
F),
that
cross
the
middle
point
of
the
diameter
of
acoustic
pore
(point
M),
to
the
intersection
point
between
the
Pendular
and
Basal
lines
(M’).
Procedure
1
Localize
and
mark
the
points
A,
B,
F,
and
M
2
Localize
and
mark
the
points
SP,
C,
D,
and
D’
3
Draw
the
lines
4
Localize
and
mark
the
point
M’
5
Measure
the
angles
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
3

Table
2
Cephalometric
tracing
of
the
parameters
of
the
pars
petrosa
evaluated
in
this
work.
1
Lateral
Angle
(LA).
The
first
line
is
traced
tangential
to
the
anterior
and
posterior
lips
of
the
internal
acoustic
canal
(not
necessarily
the
points
A
and
B).
The
second
line
is
traced
between
the
anterior
lip
of
the
meatus
and
the
outermost
point
of
the
anterior
surface
of
the
internal
acoustic
canal.
The
lower
of
the
two
angles
at
the
point
of
intersection
of
both
the
lines
is
recorded.
2
Acoustic
pore
(AP).
The
maximum
diameter
of
the
acoustic
pore.
The
length
between
points
A
and
B
measured
in
mm.
3
Medial-surface
Inflection
Angle
of
thepars
petrosa(MIA).
MIA
measures
the
divergence
between
the
anterior
(spheno-petrous,
Line
1)
and
posterior
(tympanic-petrous,
Line
2)
bony
bases.
The
angle
is
formed
by
the
intersection
of
projection
of
Line
1
(A-SP)
and
the
projection
of
the
Line
2
(D-C).
Line
2
is
tangential
to
the
posterior
facies
of
the
pars
petrosa.
When
the
surface
is
sinuous,
the
line
should
cross
the
most
anterior
tangential
point
of
the
surface.
The
inner
angle
of
the
intersection
of
both
the
lines
is
recorded
in
sexagesimal
degrees.
Because
in
some
individuals
the
anterior
surface
(Apex
partis
petrosae)
is
convex
and
the
posterior
surface
is
rounded
and
voluminous,
we
drawn
lines
that
simplified
these
shapes
(i.e.,
the
A-
SP
line)
to
reflect
only
the
inclination
of
the
bony
bases.
4
Cephalometric
Angle
of
thepars
petrosa(CAPP).
The
angle
formed
by
intersecting
Line
3
(Basal
line,
that
crosses
the
points
M’-C-D’
or
the
two
more
external
points
of
the
posterior
wall
of
the
pars
petrosa.)
and
Line
4
(Pendular
line,
from
SP
to
M’
points).
The
angle
of
intersection
of
both
the
lines
with
the
Line
F-M’
is
recorded
in
sexagesimal
degrees.
Fig.
2.
Cephalometric
tracing:
a)
lateral
angle
of
the
internal
acoustic
canal
(LA);
b)
diameter
of
Acoustic
Pore
(AP);
c)
Medial-surface
inflection
angle
(MIA);
and
d)
cephalometric
angle
of
pars
petrosa
(CAPP).
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
4

compared
in
20
%
of
the
sample
(16
male
and
16
female
individuals)
randomly
selected.
Only
the
measures
on
the
left
side
were
used,
by
convention,
for
comparisons
between
males
and
females
[1:44].
The
intra
(repeatability)
and
interobserver
(replicability)
errors
of
the
measurements
were
examined
in
10
%
of
the
sample
(8
males
and
8
females)
randomly
selected.
For
this
purpose,
we
examined
the
difference
of
means
between
the
two
measurements
conducted
by
one
of
the
researchers
(LPL)
at
different
times,
and
the
difference
of
means
between
the
measurements
of
both
researchers,
using
t-test
for
paired
samples
and
Pearson
correlation
coefficient
at
p
<
0.05.
To
evaluate
the
accuracy
of
the
method,
the
determined
sex
was
contrasted
with
the
known
sex
of
the
individual.
A
Discriminant
Analysis
was
performed
to
determine
the
percentage
of
correct
classifications
achieved
using
the
four
proposed
parameters
and
to
detect
the
discriminatory
power
of
each
of
them
in
terms
of
probability.
Statistical
analysis
was
conducted
with
SPSS
v.
21
(IBM1).
3.
Results
The
results
of
descriptive
analysis
and
confidence
intervals
(95
%
CI)
of
each
parameter
are
showed
in
the
Table
3.
The
distribution
of
the
values
is
observed
in
the
Fig.
3.
The
pairwise
comparisons
do
not
show
significant
differences
(LA:
t
=
1.131
p
=
0.262;
AP:
t
=
1.375
p
=
0.174;
MIA:
t
=
0.460
p
=
0.647;
and
CAPP:
t
=
1.552
p
=
0.176;
see
Tables
S3
and
S4).
The
evaluation
of
intraobserver
error
show
significant
differences
between
the
first
and
second
measurement
for
MIA
(t
=
2.461;
p
=
0.026),
but
not
for
the
other
parameters
(LA:
t
=
1.887
p
=
0.079;
AP:
t
=
0.715
p
=
0.485;
CAPP:
t
=
1.625
p
=
0.125).
The
evaluation
of
the
interobserver
error
showed
significant
differences
for
LA
(t
=
2.299
p
=
0.036)
and
CAPP
(t
=
3.290;
p
=
0.005),
but
not
for
PA
(t
=
1.683
p
=
0.113)
and
MIA
(t
=
3.290
p
=
0.225).
The
correlations
between
measurements
are
high,
positive,
and
significant
in
Table
3
Mean
values
of
the
evaluated
parameters
by
sex.
Sex
N
Min.
Max.
Median
Mean
SD
IC
95
%
males
LA
75
24.20
64.60
39.30
40.46
8.58
38.48–42.43
AP
75
3.60
14.10
8.70
8.63
2.23
8.12–9.15
MIA
75
130.30
179.20
156.40
157.42
10.77
154.94–159.90
CAPP
75
93.60
180.00
142.40
139.47
20.61
134.73–144.22
females
LA
75
26.70
67.90
45.50
45.78
8.24
43.88–47.67
AP
75
2.80
12.80
8.20
8.26
1.86
7.84–8.70
MIA
75
129.0
177.0
150.10
151.03
9.70
148.80–153.26
CAPP
75
34.70
167.90
112.20
106.34
31.71
99.05–113.64
Fig.
3.
Box
plots
and
values
distributions
of
the
evaluated
parameters:
a)
Lateral
Angle
(LA),
in
sexagesimal
degrees;
b)
Diameter
of
Acoustic
Pore
(AP),
in
mm;
c)
Medial-
surface
inflection
angle
of
the
pars
petrosa
(MIA),
in
sexagesimal
degrees;
d)
Cephalometric
angle
of
the
pars
petrosa
(CAPP),
in
sexagesimal
degrees.
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
5

all
cases,
with
only
one
exception
to
the
evaluation
of
interobserver
error
(AP:
r
=
0.373
p
=
0.155;
see
Tables
S5–S7).
The
comparison
of
means
between
sexes,
examined
with
a
t-test
for
independent
samples,
reveal
significant
differences
for
LA,
CAPP,
and
MIA,
but
not
for
AP
(Table
4).
Females
show
a
more
open
lateral
angle,
a
medial-surface
of
the
pars
petrosa
slightly
more
divergent
between
their
anterior
and
posterior
segments,
and
a
more
acute
cephalometric
angle.
In
all
cases,
however,
there
is
considerable
overlap
of
values,
and
establishing
a
cutoff
point
to
reasonably
differentiate
between
both
sexes
is
somewhat
difficult.
When
the
individuals
were
allocated
in
categories
according
to
the
cutoff
points
recommended
by
Norén
et
al.
[11]
for
LA
(M
<
45and
F
>
45),
only
63
%
individuals
(94/150)
were
correctly
classified.
Based
on
the
means,
medians,
standard
deviations,
and
confidence
intervals
obtained
from
our
observations
were
established
as
cutoff
points
154for
MIA
(F
<
154and
M

154)
and
134for
CAPP
(F
<
134and
M

134).
With
these
cutoff
points
these
parameters
allowed
a
correct
classification
of
61
%
(91/150)
and
71
%
(107/150)
of
individuals,
respectively.
The
discriminant
analysis
using
the
four
combined
parameters
allowed
classifying
the
correct
sex
in
72
%
of
the
individuals
(108/150
individuals).
The
parameters
used
individually
allowed
correct
classi-
fications
of
62.7
%
of
individuals
for
LA;
60
%
for
MIA
and
74
%,
the
maximum
value
reached,
for
CAPP
(Table
5).
Although
can
be
considered
“low”,
the
CAPP
showed
higher
classification
potential
than
LA
[9–12,15].
4.
Discussion
Despite
their
apparent
potential
for
determination
of
sex
in
skeletonized
individuals,
the
combined
use
of
cephalometric
measures
of
the
pars
petrosa
shows
a
relatively
limited
efficacy
in
the
correct
classification
of
sex.
There
is
a
remarkable
congruence
between
the
values
obtained
in
this
research
and
previously
published
studies
(anatomical
and
tomographic)
for
the
Lateral
Angle
(LA)
[3–18],
which
reinforces
the
statement
that
studies
with
CT
images
can
replace
osteological
studies.
However,
in
the
case
of
the
diameter
of
Acoustic
Pore
(AP),
our
results
are
approximately
3
mm
higher
on
average
for
both
sexes.
This
finding
is
possibly
related
to
the
method
used
by
Lynnerup
et
al.
[9]
and
the
more
accurate
measurements
obtained
from
this
study.
It
can
also
be
related
to
the
two-dimensional
nature
of
CT
images
and
cephalometric
tracing.
As
reported
by
previous
studies
[3,12–17],
LA
and
AP,
show
high
overlap
of
values
and
low
efficacy
when
used
individually.
Between
the
two
newer
traits
proposed
in
this
work,
the
Medial-surface
Inflection
Angle
of
the
pars
petrosa
(MIA)
proved
to
be
ineffective,
while
the
parameter
called
Cephalometric
Angle
of
the
pars
petrosa
(CAPP)
showed
greater
discriminating
power.
Although
three
parameters
show
signifi-
cant
differences
between
sexes,
in
all
cases
it
is
difficult
to
establish
cutoff
points
that
allow
differentiation
between
males
and
females.
Possibly
the
confidence
intervals
(95
%
CI)
obtained
in
this
study
represent
a
good
point
of
departure
for
future
explorations.
Discriminant
analysis
revealed
which
parameters
were
the
most
appropriate
to
differentiate
between
sexes.
The
Cephalometric
Angle
of
pars
petrosa
(CAPP)
has
the
highest
discriminant
value
and
correctly
classify
74
%
of
cases.
The
concomitant
use
of
the
other
three
measures,
reduces
the
discriminant
potential
of
the
model
by
1
%.
The
low
discriminating
value
of
the
Medial-surface
Inflection
Angle
(MIA)
and
Acoustic
Pore
diameter
(AP)
can
be
attributed
to
the
high
degree
of
overlay
of
measurements.
AL
reached
a
classification
value
of
approximately
63
%
similar
to
the
observed
in
other
studies
[6,11,16,17].
In
all
tests,
the
parameters
worked
better
in
male
individuals.
Higher
discriminant
power
in
males
was
reported
for
LA
[5,6].
The
overlap
of
LA
values
is
greater
in
older
females.
As
observed
by
pioneering
studies
[3,12]
the
age
of
individuals
seems
to
be
a
significant
factor
in
LA
expression.
A
decrease
in
LA
values
with
ageing
was
observed,
especially
in
females
over
70
years
old.
When
the
sample
is
divided
into
age-ranges,
LA
is
more
reliable
in
the
younger
cohorts
[6].
Has
been
hypothesized
that
LA
is
affected
by
the
general
masculinization
and
atrophic
processes
in
Table
4
Comparison
of
means
of
evaluated
parameters
according
sex.
Parameter
Test
t
t
df
Sig.
Mean
difference
Standard
error
of
difference
Confidence
Interval
95
%
Inferior
Superior
LA
3.872
148
.000
5.32
1.37
8.03
2.60
AP
1.076
148
.284
.36
.33
.30
1.02
MIA
3.818
148
.000
6.39
1.67
3.08
9.70
CAPP*
7.585
148
.000
33.12
4.36
24.49
41.76
*
CAPP
showed
normal
distribution
and
non-equal
variance,
for
post-hoc
comparison
of
means
the
Mann-Whitney
U
test
was
conducted:
U:
1861.500;
Z:
-3.575;
Sig:
<0.001.
Table
5
Results
of
individuals’
classification
with
Discriminant
Analysis.
Parameter
Sex
Group
of
classification
Total
Cases
correctly
classified
(%)
male
female
n
(%)
n
(%)
n
(%)
LA
male
51
(68.0)
24
(32.0)
75
(100.0)
62.7
%
female
32
(42.7)
43
(57.3)
75
(100.0)
AP
male
Do
not
qualifies
for
the
analysis
female
MIA
male
44
(58.7)
31
(41.3)
75
(100.0)
60.0
%
female
29
(38.7)
46
(61.3)
75
(100.0)
CAPP
male
60
(80.0)
15
(20.0)
75
(100.0)
74.0
%
female
24
(32.0)
51
(68.0)
75
(100.0)
LA+AP+MIA+
CAPP
male
54
(72.0)
21
(28.0)
75
(100.0)
72.0
%
female
21
(28.0)
54
(72.0)
75
(100.0)
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
6

female
skull
(especially
the
cranial
base
and
the
petrous
bone)
linked
to
hormonal
changes
caused
by
menopause
(for
an
expanded
discussion
on
this
issue
see
Massoti
et
al.
[6]).
Thus,
the
discriminating
power
of
our
markers
can
be
related
to
differences
in
the
age
distribution
of
the
sample.
A
new
study
considering
age-ranges
is
ongoing
and
should
answer
this
issue.
The
variability
observed
among
the
parameters
could
be
also
related
to
differences
of
ancestral
group
or
ethnic
origin
and
correlated
differences
in
the
skull
shape
linked
to
the
high
level
of
admixture
between
caucasoids,
negroids,
mongoloids
and
Amerindians
in
the
Brazilian
population
[20].
An
observation
that
deserves
future
evaluation
suggests
that
individuals
of
Asian
ancestry
(inferred
by
the
last
name)
have
a
lower
inflection
of
the
medial
surface
of
the
pars
petrosa
(with
approximate
angles
of
180)
in
possible
association
with
greater
brachycephaly.
Thus,
parameters
such
as
MIA
and
CAPP
could
be
more
efficient
in
Amerindians
or
Asian
individuals.
On
the
other
hand,
mongoloid
females
could
also
mimic
values
from
males
of
other
groups.
The
greatest
difficulty
of
applying
this
method
in
forensic
cases
is
the
acquisition
of
adequate
CT
images.
However,
there
are
other
limitations
that
represent
potential
sources
of
error
that
deserve
consideration:
1)
problems
with
image
standardization
and
post-processing
of
CT
images
that
can
affect
the
accuracy
of
measurements;
2)
difficulty
to
select
the
best
image
for
measurements;
3)
the
limitation
that
imposes
the
two-
dimensional
nature
of
cephalometric
tracing
in
the
representation
of
the
three-dimensional
petrous
bone;
4)
partial
volume
effects
caused
by
pixels
containing
mixture
of
tissues
that
result
in
loss
of
resolution
[16].
All
these
factors
may
also
explain
the
intra-
and
interobserver
error,
which
in
this
research
proved
to
be
significant.
Due
to
the
morphology
of
the
pars
petrosa
and
its
highly
variable
topography,
the
correct
tracing
of
the
parameters
is
the
main
obstacle
to
a
correct
application
of
the
method
in
practical
terms.
Considering
that
several
studies
have
already
focused
on
the
morphology
of
pars
petrosa
as
a
useful
trait
for
the
determination
of
sex
using
osteometric
methods
[3,7,8,11],
future
studies
applying
geometric
morphometrics
techniques
could
provide
new
insights
on
sexual
dimorphism
and
differences
between
populations.
5.
Conclusion
The
significant
differences
between
males
and
females
for
LA,
MIA,
and
CAPP
in
our
sample
suggests
some
degree
of
sexual
dimorphism
of
the
pars
petrosa
that
should
be
evaluated
with
more
sophisticated
methods.
The
discriminatory
value
of
the
integrated
parameters
reaches
72
%
of
correct
classifications.
When
used
individually,
the
Cephalometric
Angle
of
the
pars
petrosa
showed
higher
discriminating
power
(74
%
of
correct
classifications).
Tomographic-cephalometric
tracing,
due
to
its
method-
ological
limitations,
may
be
useful
for
the
determination
of
sex
only
as
indicial
method
of
identification,
in
cases
involving
very
fragmented
bones,
where
it
is
impossible
to
apply
more
reliable
methods.
Funding
This
work
was
supported
by
São
Paulo
Research
Foundation,
Brazil
(FAPESP:
2017/17580-0,
LPL).
Declaration
of
Competing
Interest
The
authors
declare
no
conflict
of
interest.
Acknowledgments
The
authors
wish
to
thank
Professor
Edson
Aparecido
Liberti
(Department
of
Anatomy
of
ICB-USP)
for
his
helpful
comments,
research
Ethics
Committee
of
the
Hospital
Beneficência
Portuguesa
de
São
Paulo,
and
the
valuable
collaboration
and
technical
support
of
the
Med
Imagem-BP
Medicina
Diagnóstica
team.
This
project
was
authorized
by
Plataforma
Brasil:
CAAE
53081816.0.0000.5483.
Appendix
A.
Supplementary
data
Supplementary
material
related
to
this
article
can
be
found,
in
the
online
version,
at
doi:https://doi.org/10.1016/j.fsir.2021.100174.
References
[1]
J.
Buikstra,
D.
Ubelaker
(Eds.),
Standards
for
Data
Collection
from
Human
Skeletal
Remains,
Arkansas
Archeological
Survey
Research
Series
n44,
Fayetteville,
Arkansas,
1994.
[2]
L.
Klepinger,
in:
Matt
Carmill,
Caye
Brown
(Eds.),
Fundamentals
of
Forensic
Anthropology.
Foundations
of
Human
Biology,
Willey
Liss,
New
Jersey,
2006.
[3]
J.
Wahl,
M.
Graw,
Metric
sex
differentiation
of
the
pars
petrosa
ossis
temporalis,
Int.
J.
Legal
Med.
114
(2001)
215–223.
[4]
I.
Kontopoulos,
K.
Penkman,
G.D.
McAllister,
N.
Lynnerup,
P.B.
Damgaard,
H.B.
Hansen,
M.E.
Allentoft,
M.J.
Collins,
Petrous
bone
diagenesis:
a
multi-analytical
approach,
Palaeogeogr.
Palaeoclimatol.
Palaeoecol.
518
(2019)
143–154.
[5]
S.
Masotti,
E.
Succi-Leonelli,
E.
Gualdi-Russo,
Cremated
human
remains:
is
measurement
of
the
lateral
angle
of
the
meatus
acusticus
internus
a
reliable
method
of
sex
determination?
Int.
J.
Legal
Med.
127
(2013)
1039–1044.
[6]
S.
Masotti,
A.
Pasini,
E.
Gualdi-Russo,
Sex
determination
in
cremated
human
remains
using
the
lateral
angle
of
the
pars
petrosa
ossis
temporalis:
is
old
age
a
limiting
factor?
Forensic
Sci.
Med.
Pathol.
15
(2019)
392–398.
[7]
M.
Graw,
Metric
sex
determination
of
the
skull
base,
Homo
50
(1999)
101–106.
[8]
M.
Graw,
H.T.
Haffner,
Morphognostically
accessible
sex
dimorphism
of
pars
petrosa
ossis
temporalis,
Med.
Legal
Agg.
1
(2000)
61–64.
[9]
N.
Lynnerup,
M.
Schulz,
A.
Madelung,
M.
Graw,
Diameter
of
the
human
internal
acoustic
meatus
and
sex
determination,
Int.
J.
Osteoarchaeol.
16
(2006)
118–123.
[10]
J.
Wahl,
Ein
Beitragzur
metrischen
Geschlechtsdiagnose
verbrannter
menschlicher
Knoschenreste-ausgearbeitet
an
der
Pars
petrosa
ossis
temporalis,
Zeitschrift
für
Rechtsmedizin
86
(1981)
79–101.
[11]
A.
Norén,
N.
Lynnerup,
A.
Czarnetzki,
M.
Graw,
Lateral
angle:
a
method
for
sexing
using
the
petrous
bone,
Am.
J.
Phys.
Anthropol.
128
(2005)
318–323.
[12]
M.
Graw,
J.
Wahl,
M.
Ahlbrecht,
Course
of
the
meatus
acusticus
internus
as
criterion
for
sex
differentiation,
Forensic
Sci.
Int.
147
(2005)
113–117.
[13]
D.
Gonçalves,
T.J.U.
Thompson,
E.
Cunha,
Sexual
dimorphism
of
the
lateral
angle
of
the
internal
auditory
canal
and
its
potential
for
sex
estimation
of
burned
human
skeletal
remains,
Int.
J.
Legal
Med.
129
(2015)
1183–1186.
[14]
H.
Schutkowski,
Über
den
diagnostichen
Wert
der
Pars
petrosa
ossis
temporalis
für
die
Geschlechtsbestimmung,
Zeitschrift
für
Morphologie
und
Anthropologie
74
(1983)
129–144.
[15]
G.
Akansel,
N.
Inan,
O.
Kurtas,
H.T.
Sarisoy,
A.
Arslan,
A.
Demirci,
Gender
and
the
lateral
angle
of
the
internal
acoustic
canal
meatus
as
measured
on
computerized
tomography
of
the
temporal
bone,
Forensic
Sci.
Int.
178
(2008)
93–95.
[16]
J.
Morgan,
N.
Lynnerup,
R.D.
Hoppa,
The
lateral
angle
revisited:
a
validation
study
of
the
reliability
of
the
lateral
angle
method
for
sex
determination
using
computed
tomography
(CT),
J.
Forensic
Sci.
58
(2)
(2013)
443–447.
[17]
P.
Panenková,
R.
Benus,
S.
Masnicová,
D.
Hojsök,
S.
Katina,
Reliability
of
sex
estimation
by
lateral
angle
method
and
metric
analysis
of
the
foramen
magnum,
Proceedings
of
the
5th
International
Anthropological
Congress
of
Ales
Hrdlicka;
2–5
Sept
2009,
Prague,
Humpolec,
Czech
Republic.
Olomouc,
Czech
Republic:
Ceska
Antropologie,
2009
Revised
in
15/10/2017
http://www.defm.fmph.uniba.sk/
katina/StKaPosterFM.pdf.
[18]
G.O.
Afacan,
T.
Onal,
G.
Akansel,
A.S.
Arslan,
Is
the
lateral
angle
of
the
internal
acoustic
canal
sexually
dimorphic
in
non-adults?
An
investigation
by
routine
cranial
magnetic
resonance
imaging,
Homo
68
(5)
(2017)
393–397.
[19]
J.C.
Long,
J.
Li,
M.E.
Healy,
Human
DNA
sequences:
more
variation
and
less
race,
Am.
J.
Phys.
Anthropol.
139
(2009)
23–34.
[20]
T.T.
Lopez-Capp,
C.
Rynn,
C.
Wilkinson,
L.A.
Saavedra
de
Paiva,
E.
Michel-Crosato,
M.
G.H.
Biazevic,
Craniometric
variation
among
Brazilian
and
Scottish
populations:
a
physical
anthropology
approach,
Braz.
J.
Oral
Sci.
17
(2018)
e18019.
L.N.
Pezo-Lanfranco,
R.G.
Haetinger
FSIR
3
(2021)
100174
7