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Determination of sex using head and neck CT
Poster No.:
C-3035
Congress:
ECR 2010
Type:
Scientific Exhibit
Topic:
Radiographers
Authors:
A. S. C. C. Germano , E. Serrao , C. Santos , M. M. F. Baptista ;
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Amadora/PT, Coimbra/PT
Keywords:
Head & Neck, Sex Determination, CT
DOI:
10.1594/ecr2010/C-3035
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Purpose
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Forensic imaging is an emerging subspecialty in Radiology.
It is well known that forensic anthropologists recognize sexually dimorphic
features of skull and face remains.
The aim of this retrospective study was to evaluate the possibility of sex
determination based only on head and neck CT.
Methods and Materials
Materials:
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We retrospectively evaluated all patients that underwent head and neck CT
(4 MDCT scanner) in the emergency ward, between May 1st, 2006 and May
31st, 2008.
Exclusion criteria:
- Patients older than 80 or younger than 20 because in young or very old
patients sexually dimorphic features aren´t evident;
- Obvious bone pathology and/or excessive tooth loss, as this would alter
jaw morphology and limit bone characterization;
- Protocol of acquisition causing impossibility of CT-3D reconstruction , as
we used 3D reconstructions to facilitate morphological evaluation.
Thus, a total of 59 patients (37M, 22F, average age 46.7) were used for the
purpose of this study.
Forensic methods:
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Methods used can be either metric or morphological [1,2,4,5,7].
Metric techniques are restricted to the population for which they were
developed and tested [1,2,7].
As we had an heterogeneous population, we used only morphological
criteria.
Skeletal sex determination is based on sexually dimorphic expressions of
bony characteristics produced through different [1]:
-Patterns
-Rates
-Periods of growth
There is a difference in rate and duration of growth in males and females
during adolescence (males have a longer and more intense adolescent
growth spurt than females)[1]
This difference is the basis of sexual dimorphism in the skull and face [1]
This pattern varies between individuals[1]
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A certain amount of overlap is inevitable, as male and female characteristics
lie along a continuum of morphological configuration [1,3]
First assessment of sex is based in overall size and architecture (rugosity)
[1,2,8]
Many morphological criteria can be used, including forehead, frontal
eminences, supra-orbital ridges, orbits, nasal aperature, nasals, malars,
zygomatics, palate, size and shape of mandible, chin shape [1,2,4]
Use of fewer, more precisely defined character traits can improve
interobserver concordance [2]
Clarity of definition, rather than number of traits are critical for effective
determination of sex by visual assessment [2]
CT methods:
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A radiologist (ES), removed identifying elements from 4 images of each
patient (2 scout view front and profile and 2 bone 3D reconstruction front
and right oblique rotation)
One radiologist (AG) and one forensic doctor (CS) blindly evaluated the
CT images and performed a morphological analysis of global size and
architecture of the skull and face and of three traits, easily evaluated in CT
images: size of mastoid, nuchal crest /external occipital protuberance and
mandibular ramus flexure, based on morphological forensic criteria.
ES then evaluated the final data and carried out a statistical data analysis
using SPSS17.
Using forensic criteria, we tried to classify the mandible, mastoid and nuchal
crest of each individual in male, female or indeterminate.
Based on the overall impression and the three criteria, we than classified
each individual.
Mandible:
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There is a distinct angulation of the posterior border of the mandibular ramus
at the level of the occlusal surface of the molars in adult males on page
4 [3]
Only manifests consistently after adolescence [3]
It is thought to result from the attachment of the muscles of mastication [3]
In most females on page 4 the posterior ramus is straight; If there is an
angulation, it is higher or lower than the molar occlusal surface [3]
Mastoid:
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The mastoid can be subjectively classified in small, medium or large [2].
Females on page 5 have small mastoids and males on page 6 have
large ones [2].
The intermediate sizes are hard to classify [2].
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Nuchal crest/external occipital protuberance:
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Nuchal crest is well marked in very muscled occipitals, and so is a male on
page 7 characteristic [1,2]
It is not evident or not so marked in females on page 8
Images for this section:
Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig. 5
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Fig. 6
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Results
Results:
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The accuracy of sex determination on page
was 76.3% regarding
observer AG and 67.8% for observer CS.
Sensitivity was 0.68-0.72 and specificity 0.67-0.78 between the observers.
Age did not have a statistically significant impact in the correct determination
of sex(p=0.387).
The direction of error for cranial sex criteria favored the female gender, 8
cases of men were assumed as women for observer A (p<0.01), and 12
cases for observer B (p<0.01).
Interobserver agreement on page
: The observed percentage of
agreement was 71%, corresponding to a Cohen´s kappa of 0.42 (p<0.01),
indicating moderate interobservers agreement [2,9]
Fig.
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References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
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Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
Page 12 of 28
Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
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Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
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Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
Results both observers:
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None of the criteria for sex determination and the final answer was
statistically significant, making each of them non-decisive for the final
answer/sex impression, for each observer.
There was no association between any criteria and the real sex of the
patient.
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Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
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Fig.
References: A. S. C. C. Germano; Department of Radiology, Hospital Professor
Doutor Fernando Fonseca EPE, Amadora, PORTUGAL
Images for this section:
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Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig. 5
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Fig. 6
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Conclusion
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The accuracy of patient sex determination using morphologic forensic
techniques in CT images in our study was inferior to the direct use of these
same techniques in human skeletal remains.
We used few CT images, the ones we though were essencial for this study
but maybe results can be improved with the complete exam and using more
criteria.
Results were affected by the fact that the radiologists had no knowlegde of
forensic criteria before this work and the forensics had no knowlegde of CT,
so we think that cooperation between the two specialties is fundamental.
As in the literature, our error favored females, which can be explained by
the fact that indeterminate individuals failed to express size and shape male
characteristics.
To our knowledge, this is the first reported attempt to develop a systematic
method for sex determination based on head and neck CT images of alone.
Solution
Please click on the following links: female on page 25 /male on page 26
Images for this section:
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Fig. 1
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Fig. 2: solution: scroll to end of conclusion
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Fig. 3: solution: scroll to end of conclusion
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References
1. Rogers TL. Determining the Sex of Human Remains Through Cranial Morphology. J
Forensic Sci 2005;50:493-500.
2. Walrath DE; Turner P.; Bruzek J. Reliability test of the Visual Assessment of Cranial
traits For Sex Determination. American Journal of Physical Anthropology 2004;125:
132-137.
3. Loth S; Henneberg M. Mandibular ramus Flexure: A New Morphologic Indicator of
Sexual Dimorphism in the Human Skeleton. American Journal of Physical Anthropology
1996; 99: 473-485.
4. Maat GJR; Mastwijk RW; Velde EAVD. On the Reliability of Non-metrical Morphological
Sex Determination of the skull compared with that of the pelvis in the Low Countries.
International journal of Osteoarcheology 1997; 7:575-580
5. Schmitttbuhl M; Minor JM; Taroni F. Sexual Dimorphism of the Human Mandible:
Demonstration by Elliptical Fourier Analysis. Int J Legal Med 2001; 115: 100-101.
6. Stephan CN; Norris RM; Henneberg M. Does Sexual Dimorphism in Facial Soft Tissue
Dephs Justify Sex Distinction in Craniofacial Identification? J Forensic Sci 2005; 50:
513-518
7. Uytterschaut HT. Sexual Dimorphis in Human Skulls. A Comparison of Sexual
Dimorphism in Different Populations. Human Evolution 1986; 1: 243-250.
8. Weiss KM. On the Systematic Bias in Skeletal Sexing. American Journal of Physical
Anthropology , 37: 239-250.
9. http://en.wikipedia.org/wiki/Cohen's_kappa
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