https://doi.org/10.1007/s00276-019-02409-2 ORIGINAL ARTICLE
Influence of sex and body mass index on facial soft tissue thickness measurements in an adult population of southwest of Iran
Ali Reza Eftekhari‑Moghadam1 · Seyed Mahmoud Latifi2 · Hamid Reza Nazifi3 · Jafar Rezaian4
Received: 13 December 2019 / Accepted: 23 December 2019
© Springer-Verlag France SAS, part of Springer Nature 2020
Abstract
Purpose Facial soft tissues have different thicknesses among different genders and ethnicities. This study was aimed to investigate the association of sex, ethnicity and body mass index (BMI) with facial soft tissue thickness measurements using magnetic resonance imaging to make a database for the Iranian southwest population (for Lur and Arab populations).
Methods In this analytical cross-sectional study, measurements of superficial soft tissues were taken at nine points of midline including glabella (GB), nasion (NA), end of nasals (END), mid-philtrum (MID), upper lip margin (UL), lower lip margin (LL), chin-lip fold (CLF), mental eminence (ME) and beneath chin (BC), eight points of axial sections including frontal tubers (FT), supraorbital margin (SO), external orbital margin (EX) and zygomatic arch (ZY) on both sides, and also two points of coronal section including both sides of the masseteric region (MST).
Results For association of sex with the measurements, NA, MID, UL, LL and BC were significantly higher in men (Pc < 0.05).
The most accurate measurement was MID with area under curve (AUC) = 85.03%, followed by UL (81.21%), NA (72.18%), LL (71.19%) and BC (68.10%). For association of ethnicity with BMI and measurements, higher amounts of GB and MID were associated in Arab patients.
Conclusion This study showed significant association of soft tissue thickness measurements with sex, BMI and ethnicities of southwest of Iran. MID had the most diagnostic value for male sex. The results of this study can be used in forensic medicine to diagnose the legal and biological identity of the corpse.
Keywords Soft tissue thickness · Anthropology · Forensic science · MRI · Plastic surgery
Background
In forensic science and archaeology, identification of humans depends on facial soft tissue reconstruction [3]. Indeed, it is a mixture of science and art that needs knowledge of
thicknesses of head and neck tissues [5]. Facial reconstruc- tion is the last way when other methods of identification of the deceased individuals such as DNA analysis and dental radiography are unsuccessful [1]. Computerized two- and three-dimensional soft tissue reconstruction techniques have been developed during the latest decades [21]. Needle punc- ture method is a manual technique using calibrated needle for measurement of the cadavers’ soft tissue thickness in various points on the face [12]. Because of its easy pro- cedure (piercing the skin by a needle), it was widely used in corpse and living individuals [19]. Computerized axial tomography (CAT scan) and conventional X-ray imaging, because of their ionizing nature, have not been a suitable choice for collecting large sample data from live human population [9]. Non-ionizing imaging techniques, such as magnetic resonance imaging (MRI) and ultrasound, are safe methods for assessment of soft tissue thickness measure- ments in live general population [16].
* Jafar Rezaian
1 Department of Anatomical Science, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
2 Department of Biostatistic and Epidemiology, School of Health, Health Research Institute, Diabetes Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
3 Legal Medicine Research Center, Iranian Legal Medicine Organization, Tehran, Iran
4 Department of Anatomical Sciences and Pathology, Lorestan University of Medical Sciences, Khorramabad, Iran
Other than using imaging techniques for living popu- lations, the whole body MRI—also called post-mortem MRI—has been recently used for corpse study. It may be used as an adjunct or alternative to autopsy [15]. In trau- matic causes of death, MRI showed different sensitivities and specificities for different parts and organs of the body [14]. Among the post-mortem imaging methods, MRI has a high spatial resolution to show soft tissue [7].
Anthropological differences of peoples of different eth- nicities are found in hard and soft tissues of their bodies.
However, soft tissue has a more dominant role in facial reconstruction [10]. From the anthropological point of view, Iran is a country with a variety of ethnicities. These ethnici- ties have physical and genetic differences [11, 18]. Lur and Arab are the ethnicities living in west and southwest of Iran [11].
There have been many articles presenting the mean soft tissue thickness data of different populations, but there have been no publications presenting such data in the south- west Iranian ethnicities so far. The present study classifies a cohort of living individuals from the Iranian southwest population according to age, body mass index (BMI) and ethnicity, and also presents the average tissue thickness of nine points of the midline, six points of the parasagittal (axial section) and two points of coronal sections measured by MRI.
The purpose of this study was to investigate the asso- ciation of sex, ethnicity and BMI with facial soft tissue thickness measurements to make a database for the Iranian southwest population and successful use of MRI for this object in forensic science. The points used for investigation of soft tissue thickness were chosen according to facial and morphometry resources.
Patients and methods
An analytical cross-sectional study was conducted includ- ing 100 living individuals (63 females and 37 males) aged between 18 and 50 years who had been referred to our department (Golestan Hospital MR imaging center, Ahvaz, Iran) for brain MRI during December 2016 and January of 2017. The chief complaint of the patients was headache.
Patients who had previous head and maxillofacial surgery, skin edema, soft tissue mass, trauma and metallic artifact (such as shrapnel and bullets) were excluded from this study.
MRI was performed on a 1.5 T MR unit (Magnetom Avanto, Siemens, Erlangen, Munchen, Germany), Tim Technology, magnetic field gradient strength Q-engine (33 mT/m @ 125 T/m/s) quadrature head coil array. The sec- tions were selected in such a way that the middle section was the true midsagittal section for all patients. T1-weighted (T1W) sagittal, axial and coronal section measurements
were used for the study (TR 400–500 ms, TE 15–25 ms, NEX 2, FOV 210–230 mm, slice thickness 4.5 mm). We used T1W sequence for this reason, which shows good ana- tomical details and fat tissue.
Measurements were taken at nine points of the midline including superficial soft tissue of glabella (GB), superficial soft tissue of nasion (NA), end of nasals (END), superficial soft tissue of mid-philtrum (MID), upper lip margin (UL), lower lip margin (LL), chin–lip fold (CLF), superficial soft tissue of mental eminence (ME) and superficial soft tissue beneath chin (BC), eight points of axial sections includ- ing frontal tubers (FT), supraorbital margin (SO), external orbital margin (EX) and superficial soft tissue of the zygo- matic arch (ZY) on both sides, as well as two points of the coronal section including both sides of the superficial soft tissue of the masseteric region (MST) (ramus of mandible) (Figs. 1, 2, 3, 4, 5). Briefly, the final measurements were GB, NA, END, MID, UL, LL, CLF, ME, BC, right FT (RFT), right SO (RSO), right EX (REX), right ZY (RZY), right MST (RMST), left FT (LFT), left SO (LSO), left LX (LEX), left ZY (LZY) and left MST (LMST).
The measurements were evaluated using Stata 14 (Stata- Corp LLC, US) software. Mean and standard deviation (SD) were calculated for all measurements. Independent t test was used to compare the measurements between male and female. Bonferroni’s correction was used to adjust the P values resulting from t test (Pc value). Then the results with significant Pc values were considered for receiver operative characteristics (ROC) curve analysis and area
Fig. 1 Measurements of the superficial soft tissue of the glabella (g), superficial soft tissue of nasion (n), end of nasal (end), superficial soft tissue of mid-philtrum (mid), upper lip margin (ul), lower lip margin (ll), chin lip fold (clf), superficial soft tissue of mental eminence (me) and superficial soft tissue of beneath chin (bc)
under ROC curves (AUC) were reported. In the cases with AUC > 70%, the ROC curve graph and three cutoff points were reported. Logistic regression and correlation analysis were used to investigate the association of ethnicity and BMI with soft tissue measurements, respectively. Alpha 0.05 was considered as the significance level. This study was approved by the ethic committee of Lorestan Univer- sity of Medical Sciences.
Results
100 participants were imported to the study. Ethnicity- wise, 40 of them were Arab and 60 of them were Lur. 63 individuals were female and 37 individuals were male.
Fig. 2 a Measurement of the superficial soft tissue of the zygomatic arch (zy) and b measurement of the orbital margin (om)
Fig. 3 Measurement of superficial soft tissue of frontal tuber (ft)
Fig. 4 Measurement of the superficial soft tissue of the masseteric region (mst)
The age range was 18–50 years. The average of BMI was 25.12 (± 3.95) kg/m2.
For association of sex with measurements, NA, MID, UL, LL and BC were significantly higher in males (Pc < 0.05).
No significant difference was found for other measurements and the bilateral points. The points with significant associa- tion were considered for ROC curve analysis. According to this, the most accurate measurement for diagnosis of sex was MID with AUC = 85.03%, followed by UL (81.21%), NA (72.18%), LL (71.19%) and BC (68.10%) (Table 1, Figs. 6, 7, 8, 9).
For association of ethnicity with BMI and measure- ments, higher amounts of GB and MID were associated in Arab patients based on logistic regression analysis (odds ratio = 2.028 and 1.284, repectively) (Table 2). For associa- tion of BMI and measurements, UL, RFT and LFT had cor- relations with BMI based on correlation analysis (positive correlation for RFT and LFT, and negative correlation for UL) (Table 3).
Discussion
This study was aimed to investigate the association of sex, ethnicity and BMI with facial soft tissue thickness measure- ments. Among the 19 measurements, 5 were associated with male sex with acceptable diagnostic values, 2 were associ- ated with Arab ethnicity and 3 had positive correlation with BMI.So far, many studies have been done to examine the facial soft tissue thickness. Studies showed that several populations
Fig. 5 Measurement of the superficial soft tissue of the supraorbital (so) region
Table 1 Association of sex with measurements (mm) using independent t test and ROC curve analysis a Mean (SD) b Non-significant c Corrected P value based on Bonferroni’s correction (P value multiplied by 19; significant at 0.05 after correction) d Area under the ROC curve (%) GBNAENDMIDULLLCLFMEBCRFTRSOREXRZYRMSTLFTLSOLEXLZYLMST Female4.66 (0.89)a4.88 (1.19)2.05 (0.71)12.20 (1.97)9.10 (1.36)9.62 (1.73)9.55 (1.61)10.83 (1.84)4.86 (1.37)4.31 (0.85)5.80 (1.00)3.42 (1.01)9.32 (2.68)22.29 (3.92)4.35 (0.85)5.77 (0.98)3.27 (1.03)9.05 (2.65)21.94 (4.38) Male4.35 (1.19)6.06 (1.55)2.08 (0.63)14.79 (1.85)11.04 (1.73)11.00 (1.80)10.25 (1.69)11.75 (2.17)5.84 (1.53)4.23 (1.05)5.42 (1.25)2.93 (0.81)8.02 (2.80)23.34 (4.46)4.30 (1.12)5.34 (1.24)2.88 (0.95)7.65 (2.98)22.65 (5.59) P value0.16000.00000.84670.00000.00000.00030.04050.02670.00140.65000.09670.01440.02340.22140.82100.06660.06170.01660.4830 Pcc valueNSb0.0019NS0.00190.00190.0057NSNS0.0266NSNSNSNSNSNSNSNSNSNS AUCd–72.18–85.0381.2171.19––68.10––––––––––
had remarkable difference in facial tissue thickness. A ques- tion is whether soft tissue thickness data from one popula- tion can be applied to facial reconstruction of people with a different ethnicity [4]. The most often quoted studies were Rhine and Moore [13] for American people, Suzuki [20]
for Mongoloids and Rhine and Campbell [12] for Ameri- can black people. Several other databases for racial groups also exist [17]. Gender and BMI are two factors that play an essential role in facial soft tissue reconstruction. Elmehal- lowi and Soliman found a considerable sexual dimorphism in facial soft tissue thickness among Egyptians [6]. Studies showed that facial variations resulting from different body types (thin, normal and obese) may limit the effectiveness
of facial reconstruction and is a contributing factor in deter- mining differences in facial soft tissue thicknesses between people [2]. An Iranian study showed that facial soft tissue thickness was higher than that in Turkish and American studies. They believed that soft tissue thickness was higher in male and was associated with increasing BMI [8].
Limitations
From the limitations of the study, it can be mentioned that there has been no previous data from other ethnicities of Iran to compare with our results. The discussed Iranian study
cutoff: >=3.39 Sen: 100%
Spe: 7.94%
cutoff: >=8.79 Sen: 5.41%
Spe: 100%
cutoff: >=4.89 Sen: 75.68%
Spe: 60.91%
0.000.250.500.751.00Sensitivity
0.00 0.25 0.50 0.75 1.00
1 - Specificity Area under ROC curve = 0.7218
Fig. 6 ROC curve analysis for NA. The red cutoff is the most central sensitive cutoff; the blue one is the most central specific cutoff; and the purple of is one of the most accurate cutoffs. Specificity is consid- ered in favor of being male (color figure online)
cutoff: >=10.63 Sen: 100%
Spe: 17.46%
cutoff: >=16.98 Sen: 10.81%
Spe: 98.41%
cutoff: >=14.24 Sen: 75.68%
Spe: 90.41%
0.000.250.500.751.00Sensitivity
0.00 0.25 0.50 0.75 1.00
1 - Specificity Area under ROC curve = 0.8503
Fig. 7 ROC curve analysis for MID. The red cutoff is the most central sensitive cutoff; the blue one is the most central specific cutoff; and the purple of is one of the most accurate cutoffs. Specificity is consid- ered as in favor of being male (color figure online)
cutoff: >=7.98 Sen: 100%
Spe: 17.46%
cutoff: >=12.88 Sen: 21.62%
Spe: 100%
cutoff: >=10.61 Sen: 62.16%
Spe: 88.89%
0.000.250.500.751.00Sensitivity
0.00 0.25 0.50 0.75 1.00
1 - Specificity Area under ROC curve = 0.8121
Fig. 8 ROC curve analysis for UL. The red cutoff is the most central sensitive cutoff; the blue one is the most central specific cutoff; and the purple of is one of the most accurate cutoffs. Specificity is consid- ered in favor of being male (color figure online)
cutoff: >=8.19 Sen: 100%
Spe: 23.81%
cutoff: >=14.3 Sen: 5.41%
Spe: 100%
cutoff: >=11.72 Sen: 40.54%
Spe: 87.30%
0.000.250.500.751.00Sensitivity
0.00 0.25 0.50 0.75 1.00
1 - Specificity Area under ROC curve = 0.7119
Fig. 9 ROC curve analysis for LL. The red cutoff is the most central sensitive cutoff; the blue one is the most central specific cutoff; and the purple of is one of the most accurate cutoffs. Specificity is consid- ered in favor of being male (color figure online)
was conducted on an Iranian general population. Therefore, this study should be repeated on other ethnicities such as Lur and Lak population of Lorestan province, Azeri, Gilak and Balouch populations. In addition, molecular studies such as human leukocyte antigen (HLA) typing can be carried out to find correlations between molecular and anatomical anthropology.
Conclusions
This study showed significant association of soft tissue thickness measurements in MRI with sex, BMI and ethnics of west of Iran. MID had the most diagnostic value for male sex. The results of this study can be used in forensic medi- cine as well as basic medical sciences. In forensic medicine, these results can be used for facial reconstruction of Iranian corpse. In basic medical sciences, these results can be used for research and education of gross anatomy. In addition, archeological and anthropological studies may benefit from the results of our study.
Acknowledgements We thank Ahvaz and Lorestan Universities of Medical Sciences for their intellectual support.
Author contribution AREM: data collection, manuscript writing.
SML: data management, data analysis. HRN: clinical consult and supervision. JR: protocol development, manuscript editing.
Funding This study has no funding source.
Compliance with ethical standards
Conflicts of interest We declare that there is no conflict of interest.
Ethical approval This study is approved by the ethics committee of Lorestan University of Medical Sciences.
Informed consent Written informed consent was obtained from all participants.
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