Postmortem contrast-enhanced computed tomography via direct large-vessel puncture.

The aim of this study was to assess the usefulness of postmortem contrast-enhanced CT (PMeCT) performed via direct large-vessel puncture when routine postmortem CT suggests a vascular lesion as the cause of death. PMeCT was performed in 9 cases (4 male, 5 female) with a mean age of 76 years (range 52-92) at the time of death. The mean time elapsed since death was 29.1 h (12.0-72.0). The location of the target vessel for puncture was determined based on the CT table position and a grid placed on the body surface. An 18-G spinal needle was advanced to the puncture site, and the needle tip was confirmed to have reached the intended blood vessel. Using negative pressure with a 20-ml syringe, the needle tip was advanced until reverse bleeding was confirmed. Diluted contrast medium was injected slowly to ensure its dispersion within the blood vessels. Following confirmation of no extravasation, additional doses of diluted contrast agent were injected in 3-4 divided doses, with CT scans obtained at each step to track the distribution of contrast agent over time. PMeCT was successful in all cases, revealing cardiac tamponade in 7 (ascending aortic dissection, n = 6; cardiac rupture, n = 1), thoracic aortic aneurysm rupture, n = 1, and iliac artery aneurysm rupture, n = 1. There were no cases of procedure-related extravasation (pseudo-lesions). When postmortem CT reveals pericardial hematoma or bleeding in the thoracic or abdominal cavity, PMeCT can identify the source of bleeding.

Objective evaluation of changes in serum transmittance over time using a portable color digitizer.

Forensic pathologists empirically understand that postmortem changes can decrease serum transparency and change its color. Such changes are potential indicators for estimating postmortem intervals; however, reports on color changes focusing on postmortem changes in serum are scarce. To elucidate the effect of postmortem intervals on serum levels, we quantitatively evaluated and investigated the relationship between serum color and time using venous blood samples obtained from three healthy male volunteers. The serum samples were separated at 0 (1 h), 1, 2, 3, 4, 7, 10, 16, 21, and 28 days of storage. Serum transmittance and color were measured using a portable color digitizer and a custom-made measurement tool, respectively. Additionally, serum sodium (Na) and potassium (K) concentrations were measured. Serum transmittance showed a logistic curve-like decrease from 0.652 ± 0.016 (0 days) to 0.101 ± 0.014 (28 days) over time. The color changed from greenish yellow (dominant wavelength: 574.4 ± 0.63 nm) to reddish orange (603.97 ± 1.31 nm). Serum Na concentration decreased, whereas serum K concentration increased along the logistic curve. Strong (0.89, p < 0.001) and inverse correlations (-0.93, p < 0.001) were observed between the serum transmittance decrease and the Na concentration decrease and the K concentration increase, respectively. Serum transmittance decreased over time, indicating a transition from bright to dark. Moreover, a strong correlation was observed between serum transmittance and electrolytes, indicating a relationship between time course, serum transmittance, and electrolytes. These findings may contribute to the estimation of postmortem intervals in the future.

Objective Evaluation of Oral and Pharyngeal Areas in Autopsy Cases of Obstructive Sleep Apnea Syndrome via Postmortem CT.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) can cause sudden death during sleep. Previous findings have suggested that OSAS development is related to maxillofacial morphology. Evaluation of facial morphology can determine the risk of developing the disease, and establishing an objective method to assess the underlying etiology of OSAS-related death would be advantageous. OBJECTIVE: The objective of this study is to determine the key features of obstructive sleep apnea syndrome (OSAS) using postmortem oral and pharyngeal computed tomography (CT). METHODS: We retrospectively assessed autopsy cases of patients with (n=25) and without (n=25) OSAS-related death. We used oral and pharyngeal CT images to compare the oral and pharyngeal cavity volume (OPCV), oral and pharyngeal soft tissue volume (OPSV), oral and pharyngeal air space volume (OPAV), and OPAV to OPCV ratio (%air). Receiver operating curve (ROC) analysis was used to determine the accuracy of OSAS prediction. We assessed participants with body mass index (BMI) values within the normal range. RESULTS: Among the 50 subjects, we observed significant between-group differences in OPSV, OPAV, and % air, whereas there were significant between-group differences in OPSV and %air among 28 subjects with normal BMI values. Both comparisons suggested that OSAS-related death was associated with low %air and high OPSV values. CONCLUSION: The %air and OPSV are useful for assessing postmortem oropharyngeal CT images. OSAS-related sudden death is likely when %air and OPSV values are ≤20.1% and ≥127.2 ml, respectively. Among those with normal BMI values, % air and OPSV values of ≤22.8% and ≥111.5 ml, respectively, predict OSAS-related sudden death.

Postmortem kinetic CT of the cervical spine and an objective index for diagnosing anterior disc space widening: A retrospective utility analysis.

Postmortem CT has limitations in identifying cervical spine injuries. Injuries at the level of the intervertebral disc (anterior disc space widening), such as rupture of the anterior longitudinal ligament or intervertebral disc, may be difficult to distinguish from normal images depending on the imaging position. We performed postmortem kinetic CT of the cervical spine in the extended position in addition to CT in the neutral position. The difference in intervertebral angles between the neutral and extended positions was defined as the intervertebral range of motion (ROM), and the utility of postmortem kinetic CT of the cervical spine for the diagnosis of anterior disc space widening and its objective index were examined based on the intervertebral ROM. Of 120 cases, 14 had anterior disc space widening: 11 had one lesion and 3 had two lesions. The intervertebral ROM for the 17 lesions was 11.85° ± 5.25° and that for the normal vertebrae was 3.78° ± 2.81°, with a significant difference between the two. ROC analysis of the intervertebral ROM between vertebrae with anterior disc space widening and the normal vertebral spaces showed an AUC of 0.903 (95 % confidence interval 0.803-1) and a cutoff value of 8.61° (sensitivity 0.96, specificity 0.82). Postmortem kinetic CT of the cervical spine revealed that the intervertebral ROM of the anterior disc space widening was increased, which facilitated identification of the injury. An intervertebral ROM that exceeds 8.61° facilitates a diagnosis of anterior disc space widening.

Objective evaluation of chest findings in infants by postmortem computed tomography.

PURPOSE: The purpose of this study was to review the findings of computed tomography (CT) performed early postmortem on infants and to clarify the postmortem CT lung findings that occur in the absence of abnormal histopathological findings. MATERIALS AND METHODS: From July 2016 to March 2022, 72 infants were autopsied with postmortem CT (41 boys 31 girls, aged 0-36 (mean 8.2) months). Autopsy and postmortem CT lung findings were compared with the causes of death identified by the autopsies, namely sudden infant death syndrome (n = 37), acute circulatory system disease (18), drowning (7), asphyxia (5), and dehydration/undernutrition (5). RESULTS: The %aerated lung volume (-700 HU or less) ranged from 0 % to 33 % (mean 1.5 %, median 0 %), being <1 % in 61 cases (84.7 %) and >3 % in 3/5 (60 %) of the dehydration/undernutrition group. The dehydration/undernutrition group showed significant preservation of lung field air content compared with the other causes of death groups (p < 0.05). Receiver characteristic curve analysis showed a cut off value of 0.8 % and area under the curve of 0.88806. The drowning group had significantly greater pleural cavity fluid retention than the other causes of death groups (p < 0.05). No correlation was found between postmortem interval and pleural cavity fluid retention. However, resuscitation time and pleural cavity fluid retention were correlated. CONCLUSION: Evaluation of CT values on postmortem lung fields of infants usually reveals a marked decrease in air content. When air content exceeds 0.8% on infant postmortem CT, dehydration/undernutrition should be considered in the differential diagnosis.

Gluing blood into gel by electrostatic interaction using a water-soluble polymer as an embolic agent.

Liquid embolic agents are widely used for the endovascular embolization of vascular conditions. However, embolization based on phase transition is limited by the adhesion of the microcatheter to the embolic agent, use of an organic solvent, unintentional catheter retention, and other complications. By mimicking thrombus formation, a water-soluble polymer that rapidly glues blood into a gel without triggering coagulation was developed. The polymer, which consists of cationic and aromatic residues with adjacent sequences, shows electrostatic adhesion with negatively charged blood substances in a physiological environment, while common polycations cannot. Aqueous polymer solutions are injectable through clinical microcatheters and needles. The formed blood gel neither adhered to the catheter nor blocked the port. Postoperative computed tomography imaging showed that the polymer can block the rat femoral artery in vivo and remain at the injection site without nontarget embolization. This study provides an alternative for the development of waterborne embolic agents.

The usefulness of measuring n-butyric acid concentration as a new indicator of blood decomposition in forensic autopsy.

In forensic medicine, although various alcohols have been reported as indicators of decomposition in collected blood, no studies have examined short-chain fatty acids as indicators. In this study, the blood n-butyric acid concentration was quantified, and the association between n-butyric acid and decomposition was investigated to determine whether the detection of n-butyric acid could be a new indicator of decomposition. Among the forensic autopsies performed from 2016 to 2018 in our laboratory, the cases were divided into decomposed (n = 20) and non-decomposed (n = 20) groups based on macroscopic findings. Blood samples collected at the time of autopsy were derivatized with 3-nitrophenylhydrazine hydrochloride after solid-phase extraction. The n-butyric acid concentration was measured using liquid chromatography-tandem mass spectrometry. In addition, ethanol and n-propanol were measured using a gas chromatography-flame ionization detector. There was a significant difference (p < 0.01) in the concentrations of n-butyric acid between the decomposed and non-decomposed groups (0.343 ± 0.259 [0.030-0.973] and 0.003 ± 0.002 [0.001-0.007] mg/mL, respectively). In the decomposed group, n-butyric acid was detected at high concentrations, even in cases where n-propanol was low. These results suggest that n-butyric acid is more likely to be an indicator of blood decomposition than n-propanol.

Objective skull fracture evaluation by using the postmortem 3D-CT skull fracture score in fatal falls.

PURPOSE: We evaluated the usefulness of skull fracture analysis using three-dimensional computed tomography skull fracture scores (3DCT-SFs) in cases of fatal falls. MATERIALS AND METHODS: From April 2016 to September 2020, 46 cases of fatal falls from great heights (33 males, 13 females; mean age: 52.7 (range: 18-89) years) were examined using routine postmortem CT. The 3DCT-SFs were determined as the sum of the fracture line lengths measured on a volume rendering image. Skull fracture severity was classified into four stages according to the 3DCT-SFs. These stages were compared by macroscopic evaluation of skull fracture severity (injury level 0: no fracture; injury level I: fracture without deviation; injury level II: fracture with deviation; injury level III: comminuted open skull fracture). The relationship between 3DCT-SFs values, the fall distance, and the hardness of the landing surface was also examined. RESULTS: Skull fractures occurred in 26 cases (56.5%). The mean 3DCT-SFs of the cases that were classified as stages I, Ⅱ, and III were 86.6 (5.0-187.0), 832.0 (235.1-1865.8), and 3582.5 (2171.6-4787.6), respectively. Upon macroscopic evaluation of fracture severity, there were 8, 10, and 8 cases of injury levels I, II, and III, respectively. The 3DCT-SFs-based stages correlated significantly with the macroscopic skull fracture severity levels (R2 = 0.936). Solid-surface fall points resulted in significantly higher 3DCT-SFs than soft surfaces. Comminuted open fracture of the skull (stage III) occurred with fall distances ≥ 24 m. CONCLUSION: The 3DCT-SFs correlate well with macroscopic findings and are useful as an objective skull fracture index.

Evaluation of oral air space volume in obstructive sleep apnea syndrome using clinical and postmortem CT imaging.

OBJECTIVES: Obstructive sleep apnea syndrome (OSAS) induces upper airway occlusion and may cause sudden death during sleep. This study sought to clarify the relationship between oral air space volume and OSAS onset, which is influenced by multiple factors, such as jawbone, dentition morphology, and oral soft-tissue volume. METHODS: (1) 50 subjects from deceased cases were divided into two groups: OSAS (25 subjects) and controls (25 subjects). (2) 28 subjects from clinical cases were divided into two groups: OSAS (9 subjects) and controls (19 subjects). In all cases, the Computed Tomography (CT) images of the facial region were obtained, and four parameters of oral area volume were analyzed in deceased and clinical cases, and comparisons and analyses were performed between OSAS and control cases. In addition, the efficiency of measurement of these parameters was evaluated using Receiver Operating Characteristic (ROC) curves in OSAS. RESULTS: (1) In deceased cases, oral soft-tissue volume (OSV), oral air-space volume (OAV), and the ratio of OAV to OSV (%air) showed a significant correlation. (2) In clinical cases, OAV and %air showed a significant correlation. In both postmortem and clinical images, a small %air value indicates a high risk of developing OSAS and a high probability of OSAS-related sudden death. CONCLUSIONS: It was shown that the %air is an index to evaluate OSAS by CT imaging of the oral region. OSAS may be indicated when the %air value is ≦ 16.0% in deceased cases and ≦ 6.6% in clinical cases.

Generation gaps in medical education: An exploratory qualitative study.

This qualitative study aimed to explore medical students' experience of generation gap in their interactions with senior teachers (aged >55) in Japan. Focus group interviews were conducted with 28 medical students (20 to 30 years, mean age 22 ±2 years, classified as millennials, with only one year of studies since starting specialised courses for medicine. The participants were interviewed in groups of four, with each interview lasting 60 minutes. Topics covered included generation gap experienced in daily life and during their studies, and work-life balance issues. The discussions were recorded and transcribed, and content analysis was applied. Four specific influential generation-gap categories were identified - distinctive sociocultural backgrounds, more recent educational media tools and faster information dissemination speed, new-era values, and challenges in communication - that were consistent with findings from previous studies. More senior personnel involved in medical education need to consider these categories to enhance effectiveness of teaching.

Sample preparation method with ultrafiltration for whole blood thiosulfate measurement.

Quantitative analysis of thiosulfate is useful for diagnosing hydrogen sulfide poisoning. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables more rapid and sensitive measurements than previous methodologies. As simple measurements of blood thiosulfate concentration are affected by the blood matrix, blood is used as the solvent to prepare the standard solution for calibration curve generation. Thus, a large amount of blood devoid of thiosulfate is required. We developed a preparation method by incorporating an ultrafiltration step to overcome this limitation and generate a calibration curve using a standard solution prepared with pure water. We used this improved method to investigate the stability of thiosulfate in refrigerated samples. To compare the effects of refrigeration, blood samples were prepared using the following two methods: one sample was treated with a 50-kDa exclusion ultrafiltration membrane and the other was not treated. The samples were stored at 4 °C, and then measured at 0, 3, 6, 24, 48, and 96 h. The incorporation of the ultrafiltration step in the measurement procedure enabled the quantification of thiosulfate, by plotting a calibration curve using a standard of pure water; it did not require a blood standard. Additionally, the reduction in whole blood thiosulfate concentration was within 10% during 2 days of refrigeration. Thus, the need for a large amount of blood to prepare the standard solution was resolved by the ultrafiltration step in test sample preparation. This method is useful to measure thiosulfate concentration and is not hindered by sample refrigeration for a few days.

Post-mortem computed tomography in sudden death by asthma.

Ground glass attenuation (GGA) of the lungs is a common finding of post-mortem computed tomography (PMCT) that is associated with pulmonary congestion and edema due to cardiac failure during the agonal period, or due to post-mortem hypostasis. However, hypo-attenuation of the lung is an atypical finding of PMCT, and is usually a consequence of hypovolemic states before death or postmortem body posture after death. Previous studies have shown a few differential diagnoses, such as hypothermia, massive hemorrhage, asphyxiation by hanging, and dehydration, for hypo-attenuation of the lung. This report presents the case of a woman who died suddenly because of an asthma attack. Our PMCT analysis demonstrated hypoattenuation of the lung in this case. We suggest fatal asthma as a differential diagnosis for the appearance of hypo-attenuation of lungs on PMCT.

Joint European Society of Paediatric Radiology (ESPR) and International Society for Forensic Radiology and Imaging (ISFRI) guidelines: paediatric postmortem computed tomography imaging protocol.

Postmortem CT for investigating childhood deaths is increasingly utilised as a noninvasive adjunct or alternative to standard autopsy; however there are no standardised published imaging protocols. This article describes a standardised imaging protocol that has been developed based on current practices of international postmortem imaging practitioners and experts. This recommendation is expected to be useful for postmortem imaging centres wishing to update their existing practices and for those starting paediatric postmortem CT as a new service.

Lung weight estimation with postmortem CT in forensic cases.

Postmortem computed tomography (CT) is a minimally invasive technique to examine internal organs before a forensic autopsy. The purpose of our study was to estimate lung weight in a forensic setting in cases of various lung states, including fluid accumulation (congestion, edema, hypostasis, and inflammation etc.) using postmortem CT. From January 2016 to July 2018, 111 deceased bodies (62 males and 59 females, aged from 18 to 95 (average 59.6) years) were examined by CT before autopsy. Both lungs of the 111 deceased were analyzed separately, making it a total of 222 samples. We extracted lung fields from CT images manually after semi-automatic detection using an image workstation. The total lung volume and 6 categories of lung volume divided according to their CT density were measured. Multiple regression analysis was performed with lung weight in autopsy as the response variable, while the 6 categories were labelled as explanatory variables. The relation between lung weight in autopsy and lung weight estimated using postmortem CT showed a high Pearson's correlation coefficient (R2 = 0.9106). Using postmortem CT, the lung weight can be estimated in forensic settings.

Estimating normal lung weight measurement using postmortem CT in forensic cases.

PURPOSE: The aim of this study is to estimate the lung weight using postmortem CT in well aerated lung autopsy cases. The correlation coefficients to the lung weight were also evaluated for the cadavers' height, weight, whole body surface area (WBSA), body mass index, and estimated lung volume. MATERIALS AND METHODS: From October 2015 to July 2016, 31 cadavers (male 12, female 19, age 20-98 (mean 66.9) y.o., postmortem interval 0.3-75.0 (5.7) days) were compared as regards body weight, height, whole body surface area (WBSA), body mass index (BMI), lung volume on CT, and total lung volume classified into several CT number categories, with their lung weight in autopsy. RESULTS: The lung weight (mean ±â€¯SE) was 284.9 ±â€¯14.8 g in right lung and 249.3 ±â€¯12.9 g in left lung. The %ALV was 79.9 ±â€¯0.9 HU (mean ±â€¯standard error (SE)) in both lungs, 80.3 ±â€¯1.3 HU in right lung, and 77.6 ±â€¯2.0 HU in left lung. Using a simple linear regression test, there was no statistically significant correlation between the lung weight and the categories (R2: body height 0.234, weight 0.224, WBSA 0.309, BMI 0.046, lung volume 0.059). The volume for each individual CT density category showed no significant correlation, but the stepwise regression test yielded an excellent correlation coefficient (R2 = 0.840). CONCLUSION: The well aerated lung weight was 284.9 ±â€¯14.8 g in right lung and 249.3 ±â€¯12.9 g in left lung, and the postmortem CT could estimate the lung weight with high correlation coefficient.

Freezing preparation for macroscopic forensic investigation in putrefied brain.

PURPOSE: To evaluate the usefulness of the applied freezing technique in putrefied brain for macroscopic investigation. MATERIALS AND METHODS: From October 2015 to September 2016, first the brains of 10 cadavers (control group: male 6, female 4, age 20-80 (mean 61.5), postmortem intervals (PMI) 14-75 (mean 29.7)days) were inspected following the standard practice (without freezing preparation), and then with 10 cadavers (freezing group: male 7, female 3, age 41-88 (mean 60.4), PMI 7-75 (mean 29.2)days) the freezing technique was used before the autopsy. The cut brain was investigated, and the gray-white matter difference was evaluated macroscopically. RESULTS: In the control group, the brain parenchyma leaked out like sludge in 5, and there was difficulty maintaining its structure in 7. The gray-white matter difference was well visible in 3, but hard to distinguish in 3, and the total scores ranged from 0 to 9 (mean 4.4) points. In the freezing group, the entire putrefied brain was extracted as a solid organ, the gray-white matter differences were well visible, and the total scores were 6.7-9 (8.3) points. The gray-white matter difference was preserved in the freezing group (p<0.05). CONCLUSION: The freezing procedures to evaluate the putrefied brain have been successfully applied, and it could be statistically more useful in putrefied brain investigation than the ordinary procedure. Postmortem CT can be useful to evaluate not only the degree of brain putrefaction, but also the degree of brain parenchyma freezing.