Quantitative analysis of intracranial hypostasis: comparison of early postmortem and antemortem CT findings

Lateralized hypostasis of the head on post mortem CT (PMCT) scanning of decomposed bodies-a marker for terminal position

Post-mortem CT (PMCT) scanning was performed on the bodies of two decomposed adult males who had died of natural causes. The bodies both showed changes of marked decomposition with a prominent swelling of tissues on one side of the head compared to the other. A review of police statements confirmed that this matched the positions of the bodies when they were found. Thus, post-mortem hypostasis of putrefactive fluids correlated in both cases with the positions that the bodies had been in when first located. This may be a simple way of identifying or confirming the positions of decomposed bodies after death. It may also assist in indicating whether a body has been moved after putrefactive fluid hypostasis has developed.

Distinguishing true from pseudo hematoma in the cervical spinal canal using postmortem computed tomography

Spinal cord injury is difficult to detect directly on postmortem computed tomography (PMCT) and it is usually diagnosed by indirect findings such as a hematoma in the spinal canal. However, we have encountered cases where the hematoma-like high-attenuation area in the cervical spinal canal was visible on PMCT, while no hematoma was observed at autopsy; we called it a "pseudo hematoma in the cervical spinal canal (pseudo-HCSC)." In this retrospective study, we performed statistical analysis to distinguish true from pseudo-HCSC. The cervical spinal canal was dissected in 35 autopsy cases with a hematoma-like high-attenuation area (CT values 60-100 Hounsfield Unit (HU)) in the spinal canal from the first to the fourth cervical vertebrae in axial slices of PMCT images. Of these 22 had a hematoma and 13 did not (pseudo-HCSC). The location and length of the hematoma-like high-attenuation and spinal cord areas were assessed on reconstructed PMCT images, true HCSC cases had longer the posterior hematoma-like area and shorter the spinal cord area in the midline of the spinal canal (P < 0.05). Furthermore, we found that true HCSC cases were more likely to have fractures and gases on PMCT while pseudo-HCSC cases were more likely to have significant facial congestion (P < 0.05). We suggest that pseudo-HCSC on PMCT is related to congestion of the internal vertebral venous plexus. This study raises awareness about the importance of distinguishing true HCSC from pseudo-HCSC in PMCT diagnosis, and it also presents methods for differentiation between these two groups.

A clear presentation of intracranial hypostasis on PMCT

Intracranial hypostasis is a common postmortem change evident on postmortem CT (PMCT), but can be readily misinterpreted as subdural hematoma by inexperienced physicians. Although PMCT is necessarily lacking contrast enhancement, we reconstructed hypostatic sinuses into three-dimensional images resembling the results of in vivo venography. This simple methodology facilitates easy recognition of intracranial hypostasis.

Comparison of fatal traumatic medico-legal cases with postmortem computed tomography and autopsy: A pilot study in Taiwan

In order to determine the performance of postmortem computed tomography (PMCT) in identifying traumatic-relevant macroscopic findings in medico-legal cases, this retrospective observational pilot study involving nine trauma casualties who had received PMCT prior to autopsy. The comparison of these findings in six anatomical regions as dictated in Injury Severity Score (ISS) were performed. 104 traumatic-relevant findings were identified with achievement of 51% congruent findings. PMCT and autopsy had additionally found 22 and 29 findings respectively. PMCT had highest sensitivity for extremity injury (81.82%), followed by chest (73.91%), head, neck and face (71.43%), and abdomino-pelvic area (50%). It had excellent detection rate in abnormal air collection, fracture, foreign body localization, internal ballistic and intracranial pathology. However, the solid organ and vascular injuries as well as integumentary lesions were the major drawback. In conclusion, incorporation of PMCT to autopsy in medico-legal investigation helps to preserve the most abundant traumatic-relevant injuries compared to either modality.

Accurate identification of traumatic lung injury (TLI) by ATR-FTIR spectroscopy combined with chemometrics

Traumatic lung injury (TLI), which is a common mechanical injury, is receiving increasing attention because of its serious hazards. In forensic practices, accurately identifying TLI is of great importance for investigations and case trials. The main goal of this research was to identify TLI utilizing attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy in combination with chemometrics. The macroscopic appearance of lung tissue showed that identifying TLI in lung tissue at the decomposition stage is not feasible by only visualization, and significant pulmonary hypostasis was observed in the lungs regardless of whether the lung tissue was injured. Average spectra and principal component analysis (PCA) suggested that the biochemical difference between injured lung tissue samples from the TLI group and noninjured lung tissue samples from the negative control group was mainly attributed to the different structures and contents of proteins. Partial least squares discriminant analysis (PLS-DA) was then utilized to identify TLI with an accuracy of 96.4% and 98.6% based on the training set and the test set, respectively. Next, we focused on samples that were misclassified in the model and proposed that the misclassification could be caused by the pulmonary hypostasis effect. Therefore, two additional PCA and PLS-DA models were created to identify the pulmonary hypostatic areas between the TLI group and the negative control group and the nonpulmonary hypostatic areas between the TLI group and the negative control group. The PCA results indicated that the biochemical difference between the two groups was still associated with proteins, and the two PLS-DA models achieved 100% accuracy based on both the training and test sets. This result indicated that when pulmonary hypostasis was considered and the lung tissue was divided into pulmonary hypostatic areas and nonpulmonary hypostatic areas for separate comparisons, TLI identification was achieved with a greater accuracy than that obtained when the two areas were combined. This research confirms that the combined application of ATR-FTIR spectroscopy and chemometrics can be utilized to accurately identify TLI.

Longitudinal comparison of ascites attenuation between antemortem and postmortem computed tomography

OBJECTIVE

To investigate the changes in ascites attenuation between antemortem (AMCT) and postmortem computed tomography (PMCT) analyses of the same subjects.

METHODS

Thirty-five subjects who underwent unenhanced or enhanced AMCT within 7 days before death, unenhanced PMCT, and autopsy were evaluated. In each subject, ascites attenuation was measured at similar sites on AMCT and PMCT. Attenuation changes were evaluated in 42 unenhanced AMCT/PMCT site pairs (23 subjects) and 20 enhanced AMCT/PMCT site pairs (12 subjects). Factors contributing to CT attenuation changes were also assessed, including the time interval between AMCT and PMCT, serum albumin level, estimated glomerular filtration rate, and ascites volume.

RESULTS

Significantly elevated CT attenuation was observed between enhanced AMCT and PMCT (12.2 ± 6.3 vs. 18.7 ± 10.4 Hounsfield units; paired t-test, p = 0.006), but not between unenhanced AMCT and PMCT (13.5 ± 8.9 vs. 13.4 ± 9.3; p = 0.554). A significant inverse association was observed between the degree of CT attenuation change and the time interval between enhanced AMCT and PMCT (Spearman's rank correlation coefficient, r = -0.56, p = 0.01).

CONCLUSIONS

We confirmed an elevated level of ascites attenuation on PMCT relative to AMCT in subjects who underwent enhanced AMCT shortly before death.

Postmortem CT in Trauma: An Overview

As forensic radiology sees an exponential gain in popularity, postmortem computed tomography (PMCT) is increasingly being used in the appropriate setting, either as preautopsy guidance or as part of complementary virtual autopsy protocol. Many articles have expounded the value it adds to forensic pathology in the general setting and the appropriate technical parameters to be used for optimum benefit. We aim to put forth a concise review on the role of PMCT specifically in trauma and the pitfalls to be aware of. Reviews have shown that presumed cause of death in trauma have been proven by autopsy to be wrong in about 30% cases. Radiology applied to postmortem investigation in unnatural deaths and more specifically in trauma shares many semiotic features with emergency radiology. Therefore, in the near future, emergency radiologists might be required to integrate this type of imaging in their regular practice. Although the predominant drawbacks are time-dependent, PMCT also has some difficulty in differentiating antemortem and postmortem events. However, in many such scenarios, PMCT and autopsy play a complementary role in arriving at conclusions, and we believe understanding the benefits and role in trauma is imperative considering the expanding usage of PMCT.

Postmortem volume change of the spleen and kidney on early postmortem computed tomography: comparison with antemortem computed tomography

PURPOSE

To clarify an early postmortem change, we investigated the volume changes of the spleen and kidney on postmortem CT compared with antemortem CT in the same patients.

MATERIALS AND METHODS

We retrospectively evaluated the volumes of 56 spleens (56 cases) and 50 kidneys (25 cases) using antemortem and postmortem CT, which were performed within 168 min after death. We divided the cases of spleen analysis into a hemorrhagic group (n = 12) and a non-hemorrhagic group (n = 44).

RESULTS

The volumes of the organs before and after death were 101.0 ± 70.9 (cm³, mean ± standard deviation) and 81.1 ± 57.8 in spleens, 120.3 ± 49.2 and 109.2 ± 39.2 in kidneys, respectively. Both spleens and kidneys shrank after death (p < 0.05). The volumes of spleens before and after death were 111 ± 66.5 and 67.5 ± 27.7 in the hemorrhagic group, and 98.2 ± 72.5 and 84.9 ± 63.3 in the non-hemorrhagic group, respectively. The median value of the ratio of postmortem splenic volume to antemortem volume in the hemorrhagic group (65.0%) was smaller than the one in the non-hemorrhagic group (90.5%) (p < 0.05).

CONCLUSION

We demonstrated that spleens and kidneys significantly reduced in size after death. The rate of shrinkage of spleens in the hemorrhagic group significantly became larger than the one in the non-hemorrhagic group.

Hematocrit Measurement with R2* and Quantitative Susceptibility Mapping in Postmortem Brain

BACKGROUND AND PURPOSE

Noninvasive venous oxygenation quantification with MR imaging will improve the neurophysiologic investigation and the understanding of the pathophysiology in neurologic diseases. Available MR imaging methods are limited by sensitivity to flow and often require assumptions of the hematocrit level. In situ postmortem imaging enables evaluation of methods in a fully deoxygenated environment without flow artifacts, allowing direct calculation of hematocrit. This study compares 2 venous oxygenation quantification methods in in situ postmortem subjects.

MATERIALS AND METHODS

Transverse relaxation (R2*) mapping and quantitative susceptibility mapping were performed on a whole-body 4.7T MR imaging system. Intravenous measurements in major draining intracranial veins were compared between the 2 methods in 3 postmortem subjects. The quantitative susceptibility mapping technique was also applied in 10 healthy control subjects and compared with reference venous oxygenation values.

RESULTS

In 2 early postmortem subjects, R2* mapping and quantitative susceptibility mapping measurements within intracranial veins had a significant and strong correlation (R² = 0.805, P = .004 and R² = 0.836, P = .02). Higher R2* and susceptibility values were consistently demonstrated within gravitationally dependent venous segments during the early postmortem period. Hematocrit ranged from 0.102 to 0.580 in postmortem subjects, with R2* and susceptibility as large as 291 seconds^-1 and 1.75 ppm, respectively.

CONCLUSIONS

Measurements of R2* and quantitative susceptibility mapping within large intracranial draining veins have a high correlation in early postmortem subjects. This study supports the use of quantitative susceptibility mapping for evaluation of in vivo venous oxygenation and postmortem hematocrit concentrations.

Total-body CT and MR features of postmortem change in in-hospital deaths

OBJECTIVES

To evaluate the frequency of total-body CT and MR features of postmortem change in in-hospital deaths.

MATERIALS AND METHODS

In this prospective blinded cross-sectional study, in-hospital deceased adult patients underwent total-body postmortem CT and MR followed by image-guided biopsies. The presence of PMCT and PMMR features related to postmortem change was scored retrospectively and correlated with postmortem time interval, post-resuscitation status and intensive care unit (ICU) admittance.

RESULTS

Intravascular air, pleural effusion, periportal edema, and distended intestines occurred more frequently in patients who were resuscitated compared to those who were not. Postmortem clotting was seen less often in resuscitated patients (p = 0.002). Distended intestines and loss of grey-white matter differentiation in the brain showed a significant correlation with postmortem time interval (p = 0.001, p<0.001). Hyperdense cerebral vessels, intravenous clotting, subcutaneous edema, fluid in the abdomen and internal livores of the liver were seen more in ICU patients. Longer postmortem time interval led to a significant increase in decomposition related changes (p = 0.026).

CONCLUSIONS

There is a wide variety of imaging features of postmortem change in in-hospital deaths. These imaging features vary among clinical conditions, increase with longer postmortem time interval and must be distinguished from pathologic changes.

Postmortem Changes as Documented in Postmortem Computed Tomography Scans

The benefits and uses of postmortem computed tomography (PMCT) have been well documented in the forensic pathology and radiology literature in recent years and research into its utility continue in earnest. Opinions and policies regarding who actually interprets the PMCT scans vary between institutions, but in general, scans will be read by a forensic pathologist, a clinical radiologist, or a clinical radiologist with a special interest or training in postmortem imaging. Differences between clinical computed tomography scans and PMCT scans have been well documented and knowledge of these differences, typically those due to postmortem changes, is essential to the reader of the PMCT scan so as to minimize the risk of misinterpretation and, potentially, misdiagnoses.

Common Postmortem Computed Tomography Findings Following Atraumatic Death: Differentiation between Normal Postmortem Changes and Pathologic Lesions

Computed tomography (CT) is widely used in postmortem investigations as an adjunct to the traditional autopsy in forensic medicine. To date, several studies have described postmortem CT findings as being caused by normal postmortem changes. However, on interpretation, postmortem CT findings that are seemingly due to normal postmortem changes initially, may not have been mere postmortem artifacts. In this pictorial essay, we describe the common postmortem CT findings in cases of atraumatic in-hospital death and describe the diagnostic pitfalls of normal postmortem changes that can mimic real pathologic lesions.

Early postmortem volume reduction of adrenal gland: initial longitudinal computed tomographic study

We aimed to confirm whether postmortem adrenal volumetric changes occur by measuring adrenal volumes on computed tomography (CT). Fifty-five adrenal glands from 28 subjects who died were included. All subjects underwent antemortem CT (AMCT) and postmortem CT (PMCT) within 94-1,191 min after death, followed by conventional autopsy. CT volumetry was performed using freely-available software. Differences between AMCT and PMCT adrenal volumes were evaluated statistically along with differences in the degree of volume change, elapsed time to PMCT, and presence of underlying malignant disease. The mean volume of the right adrenal gland decreased from 3.8 cm(3) on AMCT to 2.6 cm(3) on PMCT (P < 0.001); the left adrenal gland decreased from 4.2 cm(3) on AMCT to 3.1 cm(3) on PMCT (P < 0.001). Conventional autopsy revealed decreased intracellular lipid components in portions of the adrenal glands. No correlation between the adrenal gland reduction rate and the elapsed time from AMCT to death or from death to PMCT was observed (P = 0.99 and 0.79; P = 0.28 and 0.59 for the right and left adrenal glands, respectively). Significant differences in both the bilateral adrenal gland reduction rates and underlying malignant disease were found for the left adrenal gland (P = 0.015), but not for the right (P = 0.74). Adrenal volume reduction was observed on PMCT compared to AMCT. This highlights the need to further elucidate the mechanism of adrenal shrinkage during the agonal stage and after death. This may be explained by pathological findings of intracellular lipid depletion.

Is acute subdural hematoma reduced during the agonal stage and postmortem?

The issue of proper use of postmortem computed tomography (PMCT) in forensic fields is currently being actively discussed. The PMCT image has specific findings that differ from the antemortem image, and it is essential to understand and interpret postmortem changes in order to utilize PMCT properly. In this article, we present two cases of acute subdural hematoma (ASDH) in which images were obtained both ante- and postmortem. These images showed marked reduction of hematoma and diminishing midline shift between the agonal and postmortem periods, without evacuation of the hematoma. Attention should be paid to this phenomenon because key findings in determining cause of death could disappear if investigating the cause of death takes too long in cases that prove to be ASDH. In other words, this phenomenon potentially becomes a risk for misdiagnosis when we decide the cause of death without knowing the details of the circumstances of death.

Changes in aortic shape and diameters after death: comparison of early postmortem computed tomography with antemortem computed tomography

PURPOSE

The purpose of this study is to evaluate the postmortem deformation of the aorta on postmortem computed tomography (CT) by comparison with the antemortem CT in the same patient.

MATERIALS AND METHODS

A total of 58 non-traumatic patients without hemorrhagic events who underwent torso CT before and shortly after death were enrolled. Antemortem chest and abdominal CT were obtained in 44 cases and in 57 cases, respectively. The lengths of the major and minor axes of the ascending and descending thoracic aorta and the abdominal aorta were measured on both antemortem and postmortem CT in the same patient. To evaluate the shape of the aorta, the major axis-minor axis ratio (Ma-MiR) was calculated. Mean values of the diameters of the aorta and Ma-MiRs on postmortem CT were compared with those on antemortem CT using the Wilcoxon signed-rank test. We also evaluated the major and minor axes and Ma-MiRs on both antemortem and postmortem CT in two age groups: 65 years and under (n=13) and over 65 years (n=45).

RESULTS

At each level tested, the aorta significantly shrank after death (p<0.001) (ascending thoracic aorta, descending thoracic aorta, and abdominal aorta: 38.5 mm × 33.5 mm, 28.0 mm × 25.9 mm, and 24.4 mm × 21.8 mm on antemortem CT, 30.0 mm × 26.2 mm, 24.4 mm × 20.7 mm, and 21.5 mm × 14.5 mm on postmortem CT, respectively). The postmortem Ma-MiRs significantly increased at the descending thoracic aorta and the abdominal aorta (p<0.001). The diameters of the aorta are longer in older cases at all levels on both antemortem and postmortem CT. The reduction rates were larger in younger cases than older cases at all levels.

CONCLUSIONS

After death, the aorta shrunk at all levels, and became oval in shape in descending thoracic and abdominal aorta. The contraction was greater in younger cases than older cases. Investigators who interpret postmortem imaging should be aware of the postmortem deformation of the aorta.

Background and current status of postmortem imaging in Japan: short history of "Autopsy imaging (Ai)"

There is a low autopsy rate and wide distribution of computed tomography (CT) and magnetic resonance imaging (MRI) scanners in Japan. Therefore, many Japanese hospitals, including 36% of the hospitals with in-patient facilities and 89% of large hospitals with ER facilities conduct postmortem imaging (PMI), use clinical scanners to screen for causes in unusual deaths as an alternative to an autopsy or to determine whether an autopsy is needed. The Japanese PMI examination procedure is generally referred to as "autopsy imaging" (Ai) and the term "Ai" is now commonly used by the Japanese government. Currently, 26 of 47 Japanese prefectures have at least one Ai Center with scanners that are dedicated for PMI. Here, we briefly review the history of Japanese PMI (Ai) from 1985 to the present.

The effectiveness of postmortem multidetector computed tomography in the detection of fatal findings related to cause of non-traumatic death in the emergency department

OBJECTIVES

To investigate the diagnostic performance of postmortem multidetector computed tomography (PMMDCT) for the detection of fatal findings related to causes of non-traumatic death in the emergency department (ED).

METHODS

494 consecutive cases of clinically diagnosed non-traumatic death in ED involving PMMDCT were enrolled. The fatal findings were detected on PMMDCT and classified as definite or possible findings. These findings were confirmed by autopsy in 20 cases.

RESULTS

The fatal findings were detected in 188 subjects (38.1%) including 122 with definite (24.7%) and 66 with possible finding (13.4%). Definite findings included 21 cases of intracranial vascular lesions, 84 with intra-thoracic haemorrhage, 13 with retroperitoneal haemorrhage and one with oesophagogastric haemorrhage. In three patients who had initially been diagnosed with non-traumatic death, PMMDCT revealed fatal traumatic findings. Two definite findings (two haemopericardiums) and seven possible findings (two intestinal obstructions, one each of multiple liver tumours central pulmonary artery dilatation, pulmonary congestion, peritoneal haematoma, and brain oedema) were confirmed by autopsy. The causes of death were not determined in cases with possible findings without autopsy.

CONCLUSIONS

PMMDCT is a feasible tool for detecting morphological fatal findings in non-traumatic death in ED. It is important to know the ability and limitation of PMMDCT.