|Year : 2020 | Volume
| Issue : 4 | Page : 111-116
Comparison of “Normal” craniocerebral computed tomography of deceased and living individuals
Xiaofei Liu1, Wenju Jin2, Zhiyuan Xia2, Lan Du2, Chunsheng Li3, Qing Chen1, Li Liu1
1 Department of Forensic Pathology, Criminal Investigation Corps of Beijing Public Security Bureau, Beijing, China
2 Dian Research Center for Postmortem Imaging and Angiography, Zhejiang Dian Institute of Forensic Sciences, Hangzhou, China
3 Haidian Division of Beijing Public Security Bureau, Beijing, China
|Date of Submission||01-Oct-2020|
|Date of Acceptance||29-Oct-2020|
|Date of Web Publication||05-Jan-2021|
Criminal Investigation Corps of Beijing Public Security Bureau, Beijing 100192
Criminal Investigation Corps of Beijing Public Security Bureau, Beijing 100192
Source of Support: None, Conflict of Interest: None
To compare “normal” craniocerebral computed tomography (CT) of deceased and living individuals. Nineteen parameters of craniocerebral CT scans of 50 deceased and 50 living individuals that met specific filtering criteria were measured separately: The intensity (CT value) ratio of gray matter to white matter (GM/WM), maximum and minimum length of frontal horn of ventricle, transverse diameter of cerebral parenchyma, length of choroid plexus, maximum external diameter of body of lateral ventricle, maximum internal transverse diameter of cranium, length of cerebral longitudinal fissure, length between two calvarium, transverse and longitudinal diameter of the third and fourth ventricle, length of the cerebral longitudinal fissure, Hackman value, ventricular index (D/A), index of the somatic part of lateral ventricle (F/E), lateral ventricular body index (G/E), frontal horn index (G/A), and ventriculocranial ratio (VCR). The values of these 19 parameters for the deceased and living individuals were performed using statistical methods. There were significant statistic differences between deceased and living individuals in terms of eight craniocerebral CT parameters, including GM/WM, D/A, transverse diameter of the fourth ventricle, and length of the cerebral longitudinal fissure. The craniocerebral CT findings differ between deceased and living individuals. Knowledge of the normal postmortem craniocerebral CT parameters is key to correct postmortem craniocerebral radiopathological diagnosis.
Keywords: Craniocerebral, deceased, living individual, postmortem computed tomography, postmortem cross-sectional imaging
|How to cite this article:|
Liu X, Jin W, Xia Z, Du L, Li C, Chen Q, Liu L. Comparison of “Normal” craniocerebral computed tomography of deceased and living individuals. J Forensic Sci Med 2020;6:111-6
|How to cite this URL:|
Liu X, Jin W, Xia Z, Du L, Li C, Chen Q, Liu L. Comparison of “Normal” craniocerebral computed tomography of deceased and living individuals. J Forensic Sci Med [serial online] 2020 [cited 2021 Feb 26];6:111-6. Available from: https://www.jfsmonline.com/text.asp?2020/6/4/111/306183
| Introduction|| |
Postmortem cross-sectional imaging (PMCSI), also known as virtual autopsy (virtopsy) or autopsy imaging (Ai), is regarded as a revolutionary technology in forensic medicine and has become a new subspecialty of radiology after over 20 years of development.,, Normal (nonspecific) postmortem craniocerebral imaging is an important component of PMCSI research and is also the basic requirement of making correct diagnosis for the specific postmortem findings. Currently, some researchers have preliminarily compared postmortem and antemortem cerebral morphology at the radiological level; however, radiological comparative studies on antemortem and postmortem cerebral quantitative measurements are still lacking. In the present study, a preliminary measurement and comparison of 19 imaging indices of deceased and living brains was performed with the aim of investigating the differences between postmortem and antemortem brain imaging and to further improve the quality of diagnosis using postmortem brain imaging.
| Materials and Methods|| |
Preparation of postmortem and antemortem brain computed tomography imaging data
Preparation of postmortem brain computed tomography imaging data
Among the over 350 sets of postmortem computed tomography (PMCT) scan data (digital imaging and communications in medicine [DICOM] format) obtained from the Beijing Municipal Public Security Bureau Forensic Medicine Center collected between June 1, 2019, and May 31, 2020, 50 sets of postmortem brain CT imaging data that met the following 7 screening conditions were randomly selected: (1) Age >18 years; (2) Postmortem interval (PMI) <48 h; (3) Not frozen; (4) Underlying and direct causes of death unrelated to brain disease or injury; (5) No head trauma, disease, or deformity; (6) No eye trauma or disease; (7) Male-female ratio of 25:25.
Postmortem brain CT (SOMATOM Perspective, Siemens Medical, Erlangen, Germany) scanning protocol: Slice thickness, slice spacing: 0.6 mm; tube voltage: 120 V; tube current: 175 mA; acquisition matrix: 512 × 512.
Preparation of antemortem brain computed tomography imaging data
Among the over 2,400 antemortem brain CT (NeuViz 16 Classic CT, Neusoft Medical, Shenyang, China) scan data (DICOM format) obtained from Renhe Hospital of Integrated Traditional Chinese and Western Medicine, Hebei City between June 1, 2019, and May 31, 2020, 50 sets of antemortem brain CT imaging data were randomly selected that met the following 5 screening conditions: (1) Age >18 years; (2) no head trauma, disease, or deformity; (3) no headache, dizziness, or nausea; (4) male-female ratio of 25:25. Antemortem brain CT scanning protocol: Slice thickness, slice spacing: 5 mm; tube voltage, 130 kV; tube current: 280 mA; acquisition matrix: 512 × 512.
Measurement of postmortem and antemortem brain computed tomography imaging indices
RadiAnt image measurement software (RadiAnt DICOM Viewer v4.6.9, Medixant, Poznan, Poland) was used to measure 19 commonly used craniocerebral imaging indicators: The gray matter/white matter (GM/WM) intensity ratio, the maximum distance between the frontal horns of the lateral ventricles, the minimum distance between the frontal horns of the lateral ventricles, the brain parenchyma transverse diameter, distance between choroid plexus glomera of the lateral ventricles, maximum external diameter of the body of the lateral ventricles, maximum internal transverse diameter of the cranium, distance between the calvaria, transverse diameter of the third ventricle, longitudinal diameter of the third ventricle, transverse diameter of the fourth ventricle, longitudinal diameter of the fourth ventricle, width of the longitudinal fissure, the Hackman value, the ventricular index (D/A), the lateral ventricle body index (F/E), the lateral ventricle body width index (G/E), the frontal horn index (G/A), and the ventriculocranial ratio (VCR).,,,,, Descriptions and schematics of the measurement methods for these indices are shown in [Table 1] and [Figure 1], respectively.
|Table 1: Nineteen craniocerebral radiological indices and their measurement descriptions for deceased and living individuals|
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|Figure 1: Diagrams for measuring craniocerebral radiological indices. (a) Intensity of gray matter (1) and white matter (2); (b) Maximum (3) and minimum (4) length of the frontal horn of the ventricle, transverse diameter of cerebral parenchyma (5) and length of the choroid plexus.(6); (c) maximum external diameter of the body of the lateral ventricle (7), maximum internal transverse diameter of the cranium (8), length between the two calvarium (9); (d) Transverse (10) and longitudinal (11) diameter of the third ventricle; (e) Transverse (12) and longitudinal (13) diameter of the fourth ventricle; (f) Length of the cerebral longitudinal fissure (14)|
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Comparison of postmortem and antemortem brain computed tomography imaging
Microsoft Office Excel 2019 (Microsoft Corporation, Redmond, Washington, U. S.) was used to calculate the mean and standard deviation of the 19 imaging indices of postmortem and antemortem brains. The paired-sample t-test was performed on the 19 imaging indices of the postmortem and antemortem brains and the difference in the measured values of the two groups of indices was analyzed using IBM SPSS Statistics 23 (IBM, Armonk, New York, U.S.A).
| Results|| |
General characteristics of postmortem and antemortem brain imaging samples
In the 50 postmortem brain imaging samples collected, the age range was 20–89 years (average: 50 years), 24 h < PMI <48 h, and the causes of death included coronary heart disease (32%), drowning (32%), mechanical injury (16%), carbon monoxide poisoning (12%), mechanical asphyxiation (6%), and electrocution (2%).
Of the 50 antemortem brain imaging samples collected, the age range was between 21 and 62 years (average: 48 years), and the individuals were undergoing routine health examinations.
Comparison of basic indices of postmortem and antemortem brains
[Table 2] presents the comparison of basic indices of postmortem and antemortem brains. The results indicate that the distance between the calvaria, the maximum internal transverse diameter of the cranium, and the brain parenchyma transverse diameter were increased, and the fourth ventricle transverse diameter and longitudinal fissure width were decreased in postmortem brains compared to antemortem brains. These differences were statistically significant (P < 0.05); there were no statistically significant differences in the other basic indices.
|Table 2: Comparisons of 13 basic craniocerebral radiological indices between the deceased and the living body|
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Comparison of postmortem and antemortem brain and cranial ratio indices
[Table 3] shows the comparison of ratio indices of postmortem and antemortem brains. The results indicate that the GM/WM and D/A were decreased, and the G/E was increased in postmortem brains compared to antemortem brains. These differences were statistically significant (P < 0.05); there were no statistically significant differences in terms of the other ratio indices.
|Table 3: Comparisons of 6 craniocerebral radiological index ratios between the deceased and living individuals|
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Comparison of postmortem and antemortem computed tomography imaging morphology
[Figure 2] shows a comparison of some postmortem and antemortem CT images. The results show that the boundaries of the GM are less clear, the sulci are shallower or even absent, the transverse diameter of the fourth ventricle is decreased, and there are often high-density shadows caused by pooling blood in postmortem brains compared to antemortem brains.
|Figure 2: Morphological comparisons of craniocerebral computed tomography images between the deceased and living individuals. (a) Normal craniocerebral computed tomography image of the deceased at the centrum semiovale level, note that the differentiation loss of the gray and white matter and narrowing/absence of sulci/fissures; (b.) Normal craniocerebral computed tomography image of the living at the centrum semiovale level, note the clear differentiation of the gray and white matter (arrow, blank) and obvious sulci/fissures (triangles, blank); (c). Normal craniocerebral computed tomography image of the deceased at the fourth ventricle level, note that narrowing of the fourth ventricle (triangles, solid) and hypostasis (arrow, solid); (d). Normal craniocerebral computed tomography image of the living at the fourth ventricle level; note the normal size of the fourth ventricle level|
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| Discussion|| |
The application of the theory and technology of PMCSI to nondestructive, minimally invasive, or scalpel-free autopsy is an overall trend in forensic medicine worldwide. In particular, PMCT has become a tool for daily examination in countries such as Switzerland, Japan, the United Kingdom, and Australia. PMCT has an important practical value for postmortem brain examination. For example, PMCT has high sensitivity for skull fracture, intracranial hemorrhage, pneumocephalus, and gunshot wound brain injuries.,,, In practice, forensic physicians often encounter antemortem imaging data, and diagnostic and anatomical examination results often do not match in the preliminary stages of virtual autopsies. Therefore, we believe that virtual autopsy must first review the differences between postmortem and antemortem brain CT images and the characteristics of nonspecific brain imaging in the early postmortem period must be identified before a correct diagnosis from postmortem brain imaging can be made.
In the present study, certain screening criteria were applied in the selection of the 50 postmortem and antemortem brain CT samples to eliminate variation in postmortem index measurements caused by age, gender, brain injury or disease, and possible effects of freezing within a certain range. In addition, cadavers were selected within 48 h of death, and cases with putrefaction gas in liver and brain tissues were excluded in order to minimize the effects of decomposition on changes in nonspecific brain imaging. The 19 selected imaging measurement indices are all commonly used for early clinical imaging studies, and they are significant for assessing whether an individual has cerebral edema (or atrophy) and for providing an imaging diagnosis or opinion on brain injury, poisoning, or encephalitis based on clinical manifestations. With rapid development of clinical CT technology, these indicators are no longer used, but systematic brain imaging studies are of great significance for delving into the differences in postmortem and antemortem brain imaging. As postmortem CT imaging data is accumulated, indices for postmortem imaging will be further refined and reviewed.
The overall results of the present study showed that of the 19 selected brain imaging measurement indices, there were statistically significant differences in 8 indices between postmortem and antemortem brains. First, we found that GM/WM was decreased in postmortem brains compared to premortem brains. This is consistent with the results of studies of early postmortem brain changes by Takahashi et al. and Shirota et al.,, as well as changes in GW/WM in 128 postmortem and antemortem neonatal brains in a study by Nishiyama et al. in 2017; namely, GM intensity decreases within 70 min after death and WM intensity increases (GM/WM ratio decreases) within about 120 min. Second, the present study found for the first time that three indices;–distance between the calvaria, maximum internal transverse diameter of the cranium, and brain parenchyma transverse diameter, are higher in postmortem brains than in antemortem brains. This may be due to hypoxia and edema of brain tissue and increased volume of cranial contents after death. The latter presents as shall owing or disappearance of the sulci on gross brain CT imaging [Figure 2], as well as decreased longitudinal fissure width and fourth ventricle transverse diameter [Table 2]. These findings are also consistent with gross anatomical and histopathological changes, namely shallower sulci and widened gyri on gross pathology, as well as widened nerve cells and perivascular spaces and ischemic and hypoxic changes in nerve cells on microscopic examination. Third, the present study also found that G/E was increased in postmortem brains compared to antemortem brains. This may be because the maximum external diameter of the lateral ventricle body remains generally unchanged in the postmortem brain whereas the maximum internal transverse diameter of cranium increases [Table 2]. Finally, there are also major differences in CT images between postmortem and antemortem brains, which is consistent with the description of normal postmortem brain images by Takahashi et al. and Smith et al., Some nonspecific postmortem CT images of brain disease or injury are often subject to misdiagnosis, including misdiagnosis of postmortem blood accumulation as intracranial hemorrhage or subarachnoid hemorrhage [Figure 2]c, or misdiagnosis of unclear postmortem GM boundaries, shallow sulci and fissures, or fourth ventricle shrinkage as organic brain disease [Figure 2]a.
The present study also includes some shortcomings. First, it is not possible to select the same individuals for comparative studies before and after death nor conduct comparative studies of postmortem images and autopsy results. Second, some differences exist between the CT scanning protocols used for postmortem and antemortem samples, which limit the individual comparisons of CT values of different tissues in postmortem and antemortem brains, such as the intensity (CT values) of the lateral ventricle cerebrospinal fluid, vitreous humor, lens, and WM in cadavers. Third, the sample size of antemortem and postmortem brain CT images in the present study is small, and the distribution is not balanced (such as in age distribution, proportion of causes of death, and so on). Some older individuals (such as those aged 62 and 89 years) may have some degree of brain atrophy prior to death. Finally, due to the small sample size, further research is needed to determine whether statistically significant differences in CT imaging indices exist between brain tissues in the context of different causes of death. These factors may cause variation in the measurement results of some indices to some extent, as well as discrepancies with measurement results of larger samples in the future. Therefore, standardized CT scanning protocols are still necessary for future comparative studies of cranial CT imaging measurements between different age groups and large sample sizes of the same individuals before and after death, and between groups with different causes of death.
In summary, multiple brain CT imaging indices were measured, and brain images were systematically compared between postmortem and antemortem samples in the present study, and the results show that significant differences exist between the two. Users of postmortem imaging diagnosis should systematically study normal postmortem brain CT images to avoid applying clinical imaging diagnostic standards, which can lead to misdiagnosis.
This study has been approved by the institutional ethic review board.
This article was originally released in Chinese language in the Chinese Journal of Forensic Medicine.
Financial support and sponsorship
”10-10 Plan” forensic cadaver virtopsy technology research key project fund of the Ministry of Public Security (2019SSGG0402); China Scholarship Council (201707070113).
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]