Extraglottic Airway Device Misplacement: A Novel Classification System and Findings in Postmortem Computed Tomography.

STUDY OBJECTIVE: Extraglottic airway devices are frequently used during cardiac arrest resuscitations and for failed intubation attempts. Recent literature suggests that many extraglottic airway devices are misplaced. The aim of this study is to create a classification system for extraglottic airway device misplacement and describe its frequency in a cohort of decedents who died with an extraglottic airway device in situ. METHODS: We assembled a cohort of all decedents who died with an extraglottic airway device in situ and underwent postmortem computed tomographic (CT) imaging at the state medical examiner's office during a 6-year period, using retrospective data. An expert panel developed a novel extraglottic airway device misplacement classification system. We then applied the schema in reviewing postmortem CT for extraglottic airway device position and potential complications. RESULTS: We identified 341 eligible decedents. The median age was 47.0 years (interquartile range 32 to 59 years). Out-of-hospital personnel placed extraglottic airway devices in 265 patients (77.7%) who subsequently died out of hospital; the remainder died inhospital. The classification system consisted of 6 components: depth, size, rotation, device kinking, mechanical blockage of ventilation opening, and injury. Under the system, extraglottic airway devices were found to be misplaced in 49 cases (14.4%), including 5 (1.5%) that resulted in severe injuries. CONCLUSION: We created a novel extraglottic airway device misplacement classification system. Misplacement occurred in greater than 14% of cases. Severe traumatic complications occurred rarely. Quality improvement activities should include review of extraglottic airway device placement when CT images are available and use the classification system to describe misplacements.

Antemortem identification by fusion of MR and CT of the paranasal sinuses.

Radiologic forensic identification is usually performed by comparing antemortem and postmortem radiographs. While computed tomography (CT) has become a valuable addition to radiologic identification, magnetic resonance (MR) imaging has only rarely been used for this purpose. In our case, identification was accomplished using fused MR- and CT images in a survivor of a gunshot injury to the head. This case supports and highlights the possibility to perform intermodality radiologic identification comparing preexisting MR imaging to subsequently aquired CT data in living (or deceased) humans as long as manual modifications of windowing, color and contrast enable differentiation of the two modalities in the fused image.

Accuracy of non-contrast PMCT for determining cause of death.

The aim of this study was (1) to compare levels of accuracy regarding the categorization of causes of death between non-contrast post-mortem computed tomography (PMCT) and the final forensic report as well as between autopsy and the final forensic report, and (2) to assess levels of confidence regarding the categorization of causes of death after non-contrast PMCT and after autopsy. This prospective study was conducted over a 5 month period during which 221 cases were admitted to our institute for forensic investigations. Whole-body PMCT and forensic autopsy were performed in every case. Of these, 101 cases were included in the final study population. Inclusion criteria were: (1) age > 18 years, (2) presence of at least one of the two principal investigators at the time of admission. One radiologist and one forensic pathologist independently read all PMCT datasets using a report template. Cause of death category and confidence levels were determined by consensus. Forensic autopsy was performed by two forensic pathologists; both unblinded to imaging results. Both post-imaging and post-autopsy cause of death categorization were compared against the final cause of death, as stated in the forensic expert report, which included findings from histology and/or toxicology. Accuracy of post-imaging cause of death categorization in reference to the final cause of death category was substantial (82%, 83/101 cases, Kappa 0.752). Accuracy of post-autopsy cause of death categorization in reference to the final cause of death category was near perfect (89%, 90/101 cases, Kappa 0.852). Post-imaging sensitivity and specificity regarding the categorization of causes of death were 82% and 97%, respectively. Post-autopsy sensitivity and specificity regarding the categorization of causes of death were 89% and 98%, respectively. There was a high consistency between the accuracy of post-imaging cause of death categorization and post-imaging levels of confidence. There was less consistency between accuracy of post-autopsy cause of death categorization and post-autopsy levels of confidence. In this study categorization of causes of death based on non-contrast enhanced PMCT alone, and on PMCT and macroscopic autopsy together, proved to be consistent with the final cause of death-category as determined based on all available information including PMCT, autopsy, and (if available) histology and/or toxicology in more than 82% and 89% of all cases, respectively. There was higher consistency between levels of confidence and accuracy of causes of death categorization was higher post-imaging than post-autopsy. These results underline the fact that the diagnostic potential of PMCT goes beyond the assessment of trauma cases.

Distal tibia allograft for glenohumeral instability: does radius of curvature match?

BACKGROUND: A distal tibia osteochondral allograft is a potential graft option for glenoid reconstruction because the distal tibia may have a similar radius of curvature (ROC) as the glenoid. This study evaluated ROC mismatch as measured on computed tomography (CT) scans between the glenoid, distal tibia, and humeral head. METHODS: Bilateral CT images were formatted for 10 decedents from the Office of the Medical Investigator database, giving 20 specimens per anatomic location. The ROCs of the glenoid, distal tibia, and humeral head were measured. A statistical model was generated to assess ROC mismatch of randomly paired distal tibias and glenoids. RESULTS: The mean ± standard deviation ROC was 2.9 ± 0.25 cm for the glenoid, 2.3 ± 0.21 cm for the distal tibia, and 2.5 ± 0.12 cm for the humeral head. No differences were found in laterality, intraobserver, or interobserver measurements. The least-squares difference in the ROC between the glenoid and tibia was 0.57 cm, glenoid and humerus was 0.40 cm, and humerus and tibia was 0.17 cm. Only 22% of randomly paired distal tibias and glenoids had a difference in ROC of 0.3 cm or less. CONCLUSION: CT measurement of the ROC of the glenoid, distal tibia, and humeral head is reliable and reproducible. The probability of obtaining a random distal tibia allograft with a similar ROC to the glenoid is low. Obtaining ROC measurements of the injured glenoid and the distal tibia allograft specimen before use for glenoid reconstruction may be useful.

Quantification of pleural effusion from single area measurements on CT.

The objective of this study was to determine if area measurements of pleural fluid on computed tomography (CT) reflect the actual pleural fluid volume (PEvol) as measured at autopsy, to establish a formula to estimate the volume of pleural effusion (PEest), and to test the accuracy and observer reliability of PEest.132 human cadavers, with pleural effusion were divided into phase 1 (n = 32) and phase 2 (n = 100). In phase 1, PEvol was compared to area measurements on axial (axA), sagittal (sagA), and coronal (corA) CT images. Linear regression analysis was used to create a formula to calculate PEest. In phase 2, intra-class correlation (ICC) was used to assess inter-reader reliability and determine the agreement between PEest and PEvol. PEvol correlated to a higher degree to axA (r s mean = 0.738; p < 0.001) than to sagA (r s mean = 0.679, p < 0.001) and corA (r s mean = 0.709; p < 0.001). PEest can be established with the following formula: axA × 0.1 = PEest. Mean difference between PEest and PEvol was less than 40 mL (ICC = 0.837-0.874; p < 0.001). Inter-reader reliability was higher between two experienced readers (ICC = 0.984-0.987; p < 0.001) than between an inexperienced reader and both experienced readers (ICC = 0.660-0.698; p < 0.001). Pleural effusions may be quantified in a rapid, reliable, and reasonably accurate fashion using single area measurements on CT.

Material differentiation in forensic radiology with single-source dual-energy computed tomography.

The goal of this study was to investigate the use of dual-energy computed tomography (CT) in differentiating frequently encountered foreign material on CT images using a standard single-source CT scanner. We scanned 20 different, forensically relevant materials at two X-Ray energy levels (80 and 130 kVp) on CT. CT values were measured in each object at both energy levels. Intraclass correlation coefficient (ICC) was used to determine intra-reader reliability. Analysis of variance (ANOVA) was performed to assess significance levels between X-Ray attenuation at 80 and 130 kVp. T test was used to investigate significance levels between mean HU values of individual object pairings at single energy levels of 80 and 130 kVp, respectively. ANOVA revealed that the difference in attenuation between beam energies of 80 kVp compared to 130 kVp was statistically significant (p < 0.005) for all materials except brass and lead. ICC was excellent at 80 kVp (0.999, p < 0.001) and at 130 kVp (0.998, p < 0.001). T test showed that using single energy levels of 80 and 130 kVp respectively 181/190 objects pairs could be differentiated from one another based on HU measurements. Using the combined information from both energy levels, 189/190 object pairs could be differentiated. Scanning with different energy levels is a simple way to apply dual-energy technique on a regular single-energy CT and improves the ability to differentiate foreign bodies with CT, based on their attenuation values.

Fatal left ventricular rupture and pericardial tamponade following a horse kick to the chest.

Horse kicks are rare incidents-especially, if they end in fatality. In this case, a 13-year-old girl collapsed 3 minutes after sustaining a kick to the chest from a pony. Resuscitation attempts were unsuccessful. Postmortem computed tomography and magnetic resonance imaging were performed before autopsy.Imaging revealed a 3-cm long laceration of the left ventricle and a large pericardial effusion. Using segmentation techniques, the amount of blood inside the pericardium was determined. These findings correlated well with the autopsy findings. Pericardial tamponade was determined at autopsy to be the cause of death.Postmortem imaging may prove useful for the diagnosis of these types of injury, but further studies are needed to document accuracy.

Postmortem Computed Tomography in Firearm Homicides: A Retrospective Case Series.

Postmortem computed tomography (PMCT) is integrated into the evaluation of decedents in several American medical examiner offices and medicolegal death investigative centers in many other countries. We retrospectively investigated the value of PMCT in a series of firearm homicide cases from a statewide centralized medical examiner's office that occurred during 2016. Autopsies were performed or supervised by board-certified forensic pathologists who reviewed the PMCT scans prior to autopsy. PMCT scans were re-evaluated by a forensic radiologist blinded to the autopsy findings and scored by body region (head-neck, thoracoabdominal, and extremities). Injury discrepancies were scored using a modified Goldman classification and analyzed with McNemar's test. We included 60 males and 20 females (median age 31 years, range 3-73). Based on PMCT, 56 (79.1%) cases had injuries relevant to the cause of death in a single body region (24 head-neck region, 32 thoracoabdominal region). Out of these 56 cases, 9 had a missed major diagnosis by PMCT outside that region, including 6 extremity injuries visible during standard external examination. Yet all had evident lethal firearm injury. We showed that PMCT identifies major firearm injuries in homicide victims and excludes injuries related to the cause of death in other regions when a single body region is injured. Although PMCT has a known limited sensitivity for soft tissue and vascular pathology, it can be combined with external examination to potentially reduce or focus dissections in some of these cases depending on the circumstances and medicolegal needs.

The Role of Postmortem Computed Tomography in the Evaluation of Strangulation Deaths.

We explored the value of postmortem computed tomography (PMCT) to augment autopsy in evaluating strangulation fatalities. A literature search identified 16 studies describing autopsy findings in 576 deaths and two studies describing autopsy and PMCT findings in six deaths. Similar cases were identified from our institution, yielding 130 deaths with autopsy findings and 14 deaths with both autopsy and PMCT findings. The presence of laryngohyoid fracture and soft tissue hemorrhage was compared from autopsy and autopsy+PMCT cases. The detection rates of fractures in autopsy and autopsy+PMCT cases were not significantly different. PMCT identified all fractures observed at autopsy and five fractures not identified. While PMCT may not detect soft tissue injuries in decomposed remains or subtle internal hemorrhages in neck injury, it is equally able to detect bony injuries as autopsy and might surpass autopsy in detecting subtle fractures. We conclude PMCT is useful to supplement autopsy in strangulation cases.

A new method for estimating patient body weight using CT dose modulation data.

BACKGROUND: Body weight (BW) is a relevant metric in emergency care. However, visual/physical methods to estimate BW are unreliable. We have developed a method for estimating BW based on effective mAs (mAseff) from computed tomography (CT) dose modulation. METHODS: The mAseff of CT examinations was correlated with the BW of 329 decedents. Linear regression analysis was used to calculate an equation for BW estimation based on the results of decedents with a postmortem interval (PMI) < 4 days (n = 240). The equation was applied to a validation group of 125 decedents. Pearson correlation and t-test statistics were used. RESULTS: We found an overall strong correlation between mAseff and BW (r = 0.931); r values ranged from 0.854 for decedents with PMI ≥ 4 days to 0.966 for those with PMI < 4 days; among the latter group, r was 0.974 for females and 0.960 for males and 0.969 in the presence and 0.966 in the absence of metallic implants (all correlations with p values < 0.001). The estimated BW was equal to 3.732 + (0.422 × mAseff) - (3.108 × sex index), where the sex index is 0 for males and 1 for females. The validation group showed a strong correlation (r = 0.969) between measured BW and the predicted BW, without significant differences overall (p = 0.119) as well as in female (p = 0.394) and in male decedents (p = 0.196). No outliers were observed. CONCLUSIONS: CT dose modulation is a rapid and reliable method for BW estimation with potential use in clinical practice, in particular in emergency settings.

Comparative radiologic identification with standardized single CT images of the paranasal sinuses-Evaluation of inter-rater reliability.

The aim of this study was to assess the reproducibility of a standardized image for personal identification (SIPI), used in the comparative analysis of paranasal sinuses, and test the effect of inaccurate reformation of the SIPI on suitability for comparative identification. Five raters with different professional backgrounds independently reformatted SIPIs from ten post-mortem head CTs. Inter-rater, intra-rater agreement as well angular deviations between reformatted SIPI images and reference SIPI images were calculated. Second, raters assessed the suitability of 70 accurately and inaccurately reformatted SIPIs for identification with a 4-point Likert scale. Inter-rater agreement as well as levels of significance regarding image suitability were calculated. Inter-rater agreement regarding reproducibility of SIPI reformation was excellent (inter-rater correlation coefficient (ICC) 0.9995, intra-rater ICC 0.9983). Deviation between the angular dimensions of the reformatted SIPIs and the reference SIPIs was ≤1° in 94% of all 300 measurements. Inter-rater agreement regarding the effect of inaccurate SIPI reformation on suitability for comparative identification was fair (ICC 0.6809). There was no statistically significant difference between raters' evaluation of image suitability (p=0.9755). This study shows that the standardized image for personal identification can be accurately reformatted by different raters with varying professional backgrounds. In addition, raters agree that inaccurately reformatted SIPIs are still suitable for comparative identification in the majority of cases.

Comparative Evaluation of Potentially Radiolucent Projectile Components by Radiographs and Computed Tomography.

Projectile components that are traditionally radiolucent can be of considerable importance in determination of weapon type and caliber, but they are often missed on evaluation of postmortem radiographs. We hypothesized that these components would be significantly better visualized by evaluation of computed tomography (CT) scans compared to the practice standard of radiography alone. In this project, potentially radiolucent projectile components were both pulled apart and fired, and the radiolucent components were recovered. These components were embedded in blocks of ballistics gelatin and were imaged using both radiography and CT. The scans were evaluated by three blinded, board-certified radiologists for the presence/absence of projectile components and true-negative regions in each block. If a radiologist indicated visualization of a projectile component, they were further requested to describe their observation. It was found that traditionally radiolucent projectile components are not significantly more often identified on CT scans than radiography (p < 0.05).

Postmortem magnetic resonance imaging: Reproducing typical autopsy heart measurements.

PURPOSE: The aim of this study was to evaluate the utility of cardiac postmortem magnetic resonance (PMMR) to perform routine measurements of the ventricular wall thicknesses and the heart valves and to assess if imaging measurements are consistent with traditional autopsy measurements. METHODS: In this retrospective study, 25 cases with cardiac PMMR and subsequent autopsy were included. The thicknesses of the myocardial walls as well as the circumferences of all heart valves were measured on cardiac PMMR and compared to autopsy measurements. Paired samples T-test and the Wilcoxon-Signed rank test, were used to compare autopsy and cardiac PMMR measurements. For exploring correlations, the Pearson's Correlation coefficient and the Spearman's Rho test were used. RESULTS: Cardiac PMMR measurements of the aortic and pulmonary valve circumferences showed no significant differences from autopsy measurements. The mitral and tricuspid valves circumferences differed significantly from autopsy measurements. Left myocardial and right myocardial wall thickness also differed significantly from autopsy measurements. Left and right myocardial wall thickness, and tricuspid valve circumference measurements on cardiac PMMR and autopsy, correlated strongly and significantly. CONCLUSION: Several PMMR measurements of cardiac parameters differ significantly from corresponding autopsy measurements. However, there is a strong correlation between cardiac PMMR measurements and autopsy measurements in the majority of these parameters. It is important to note that myocardial walls are thicker when measured in situ on cardiac PMMR than when measured at autopsy. Investigators using post-mortem MR should be aware of these differences in order to avoid false diagnoses of cardiac pathology based on cardiac PMMR.

New evidence for old lore--urinary bladder distension on post-mortem computed tomography is related to intoxication.

INTRODUCTION: Distension of the urinary bladder is reported to be a sign of intoxication at autopsy. The purpose of this study was to compare radiologically calculated urinary bladder volume (UBV) to autopsy measurements of UBV, and to investigate the relationship between intoxication and calculated UBV. MATERIALS AND METHODS: Autopsy reports, toxicology reports and post-mortem CTs of 332 adult human cadavers were retrospectively analyzed, 259 cases were included in the final population. Spearman's rho test was used to compare calculated UBV to autopsy measurements. Significance levels for UBV in relation to toxicology results were investigated with the Mann-Whitney test. Spearman's rho test was also used to correlate the widest left-right bladder diameter on axial images to calculated UBV. Both calculated UBV and axial diameters were subjected to receiver operating characteristics curve analysis. Sensitivity and specificity were calculated for individual cutoff values. RESULTS: There is a strong correlation and high consistency (r=0.92, p<0.001) between the measured and calculated UBV. Positive toxicology results strongly correlate with calculated UBV (p<0.001). Additionally, there is a strong correlation between calculated UBV and axial urinary bladder diameter (p<0.001). UBV of 182 ml and >330 ml indicate positive toxicology results with a sensitivity/specificity of 40%/87% and 25%/97% respectively. Axial urinary bladder diameter of 8.5 cm and >10 cm indicate positive toxicology results with a sensitivity/specificity of 36%/85% and 16%/95% respectively. CONCLUSIONS: Radiologically calculated UBV accurately represents the autoptically measured UBV. The occurrence of urinary bladder distension on post-mortem imaging should raise suspicion of intoxication.

Post-mortem virtual estimation of free abdominal blood volume.

PURPOSE: The purpose of this retrospective study was to examine the reliability of virtually estimated abdominal blood volume using segmentation from postmortem computed tomography (PMCT) data. MATERIALS AND METHODS: Twenty-one cases with free abdominal blood were investigated by PMCT and autopsy. The volume of the blood was estimated using a manual segmentation technique (Amira, Visage Imaging, Germany) and the results were compared to autopsy data. Six of 21 cases had undergone additional post-mortem computed tomographic angiography (PMCTA). RESULTS: The virtually estimated abdominal blood volumes did not differ significantly from those measured at autopsy. Additional PMCTA did not bias data significantly. CONCLUSION: Virtual estimation of abdominal blood volume is a reliable technique. The virtual blood volume estimation is a useful tool to deliver additional information in cases where autopsy is not performed or in cases where a postmortem angiography is performed.

Format preferences of district attorneys for post-mortem medical imaging reports: understandability, cost effectiveness, and suitability for the courtroom: a questionnaire based study.

AIMS: The objective of this study was to explore the perception of the legal authorities regarding different report types and visualization techniques for post-mortem radiological findings. METHODS: A standardized digital questionnaire was developed and the district attorneys in the catchment area of the affiliated Forensic Institute were requested to evaluate four different types of forensic imaging reports based on four cases examples. Each case was described in four different report types (short written report only, gray-scale CT image with figure caption, color-coded CT image with figure caption, 3D-reconstruction with figure caption). The survey participants were asked to evaluate those types of reports regarding understandability, cost effectiveness and overall appropriateness for the courtroom. RESULTS AND CONCLUSION: 3D reconstructions and color-coded CT images accompanied by written report were preferred regarding understandability and cost/effectiveness. 3D reconstructions of the forensic findings reviewed as most adequate for court.

"Drug mules" as a radiological challenge: sensitivity and specificity in identifying internal cocaine in body packers, body pushers and body stuffers by computed tomography, plain radiography and Lodox.

PURPOSE: The purpose of our study was to retrospectively evaluate the specificity, sensitivity and accuracy of computed tomography (CT), digital radiography (DR) and low-dose linear slit digital radiography (LSDR, Lodox(®)) in the detection of internal cocaine containers. METHODS: Institutional review board approval was obtained. The study collectively consisted of 83 patients (76 males, 7 females, 16-45 years) suspected of having incorporated cocaine drug containers. All underwent radiological imaging; a total of 135 exams were performed: nCT=35, nDR=70, nLSDR=30. An overall calculation of all "drug mules" and a specific evaluation of body packers, pushers and stuffers were performed. The gold standard was stool examination in a dedicated holding cell equipped with a drug toilet. RESULTS: There were 54 drug mules identified in this study. CT of all drug carriers showed the highest diagnostic accuracy 97.1%, sensitivity 100% and specificity 94.1%. DR in all cases was 71.4% accurate, 58.3% sensitive and 85.3% specific. LSDR of all patients with internal cocaine was 60% accurate, 57.9% sensitive and 63.4% specific. CONCLUSIONS: CT was the most accurate test studied. Therefore, the detection of internal cocaine drug packs should be performed by CT, rather than by conventional X-ray, in order to apply the most sensitive exam in the medico-legal investigation of suspected drug carriers. Nevertheless, the higher radiation applied by CT than by DR or LSDR needs to be considered. Future studies should include evaluation of low dose CT protocols in order to address germane issues and to reduce dosage.