Ventilated post-mortem computed tomography through the use of a definitive airway

Postmortem chest computed tomography in COVID-19: A minimally invasive autopsy method

Objectives

Performing autopsies in a pandemic scenario is challenging, as the need to understand pathophysiology must be balanced with the contamination risk. A minimally invasive autopsy might be a solution. We present a model that combines radiology and pathology to evaluate postmortem CT lung findings and their correlation with histopathology.

Methods

Twenty-nine patients with fatal COVID-19 underwent postmortem chest CT, and multiple lung tissue samples were collected. The chest CT scans were analyzed and quantified according to lung involvement in five categories: normal, ground-glass opacities, crazy-paving, small consolidations, and large or lobar consolidations. The lung tissue samples were examined and quantified in three categories: normal lung, exudative diffuse alveolar damage (DAD), and fibroproliferative DAD. A linear index was used to estimate the global severity of involvement by CT and histopathological analysis.

Results

There was a positive correlation between patient mean CT and histopathological severity score indexes - Pearson correlation coefficient (R) = 0.66 (p = 0.0078). When analyzing the mean lung involvement percentage of each finding, positive correlations were found between the normal lung percentage between postmortem CT and histopathology (R=0.65, p = 0.0082), as well as between ground-glass opacities in postmortem CT and normal lungs in histopathology (R=0.65, p = 0.0086), but negative correlations were observed between ground-glass opacities extension and exudative diffuse alveolar damage in histological slides (R=-0.68, p = 0.005). Additionally, it was found is a trend toward a decrease in the percentage of normal lung tissue on the histological slides as the percentage of consolidations in postmortem CT scans increased (R =-0.51, p = 0.055). The analysis of the other correlations between the percentage of each finding did not show any significant correlation or correlation trends (p ≥ 0.10).

Conclusions

A minimally invasive autopsy is valid. As the severity of involvement is increased in CT, more advanced disease is seen on histopathology. However, we cannot state that one specific radiological category represents a specific pathological correspondent. Ground-glass opacities, in the postmortem stage, must be interpreted with caution, as expiratory lungs may overestimate disease.

Impact of the COVID-19 pandemic on a post-mortem CT service for adult non-suspicious death

Due to the COVID-19 pandemic, the post-mortem computed tomography (PMCT) service was expanded from three to seven cases per day to help mortuary services and avoid invasive autopsy. Additional targeted angiography and pulmonary ventilation procedures were stopped and triage rules relaxed to allow more indications to be scanned, including those requiring toxicology. A service evaluation was performed for the first 3-months of the COVID-19 pandemic compared to the equivalent period the previous year to study the impact of these changes. It was found that, despite the increase in deaths regionally, coronial referrals remained about 100 per month, a reduction in referral rate. The number undergoing PMCT rose from 28% to 74% of cases. Turnaround time remained the same. For cases triaged to PMCT, the need for subsequent autopsy increased from 7.9% to 15.8%. No significant changes were seen in diagnosis rates, including cardiac or respiratory. There was an increase in patients with coronary death without severe coronary calcification who underwent autopsy after PMCT. These may have been diagnosed by targeted coronary angiography. Fifty-three cases requiring toxicology/biochemistry had PMCT, with 38 having PMCT only. In 8/11 (72.7%) cases with normal PMCT and toxicology as the key diagnostic test, autopsy was performed prior to results. This suggests the pathology team were reluctant to risk an "unascertained" outcome. This study shows that it is possible to increase PMCT services by widening referral criteria and by limiting the use of enhanced imaging techniques, without significantly changing diagnosis rates of key diseases; however, selectively restarting targeted angiography may help avoid autopsy in some cases.

Ventilated postmortem computed tomography to evaluate the lungs of dogs with and without focal lung lesions

OBJECTIVE

To identify the optimal ventilation pressure for ventilated postmortem CT assessment of the lungs in cadaveric dogs and compare the optimal ventilation pressures between dogs with and without focal lung lesions.

SAMPLE

12 cadaveric dogs.

PROCEDURES

CT was performed with dogs positioned in sternal recumbency within 30 to 180 minutes after death. After orotracheal intubation, lungs were aerated to ventilation pressures of 0, 10, 15, 20, 25, 30, and 35 cm H₂O. Lung attenuation measurements were made at 5 predetermined anatomical locations with use of a multi-image analysis graphic user interface tool. Lungs were considered hyperaerated (-1000 to -901 HU), normo-aerated (-900 to -501 HU), poorly aerated (-500 to -101 HU), and nonaerated (-100 to 100 HU) on the basis of lung attenuation values. Optimal ventilation pressure was defined as the pressure at which the percentage of normo-aerated lung was greatest. For analysis, dogs were assigned to one group when focal lung lesions were evident and to another group when lesions were not evident.

RESULTS

Median optimal ventilation pressure was significantly higher for those dogs with lung lesions (35 cm H₂O), compared with those without (25 cm H₂O).

CONCLUSIONS AND CLINICAL RELEVANCE

A ventilation pressure of 35 cm H₂O may be considered for ventilated postmortem CT to determine the presence of focal lung lesions; however, further investigation is required.

Clinical Relevance of Unexpected Findings of Post-Mortem Computed Tomography in Hospitalized Patients: An Observational Study

Background and objective: The current literature describing the use of minimally invasive autopsy in clinical care is mainly focused on the cause of death. However, the identification of unexpected findings is equally important for the evaluation and improvement of daily clinical care. The purpose of this study was to analyze unexpected post-mortem computed tomography (PMCT) findings of hospitalized patients and assess their clinical relevance. Materials and methods: This observational study included patients admitted to the internal medicine ward. Consent for PMCT and autopsy was requested from the next of kin. Decedents were included when consent for at least PMCT was obtained. Consent for autopsy was not obtained for all decedents. All findings reported by PMCT were coded with an International Classification of Diseases (ICD) code. Unexpected findings were identified and subsequently categorized for their clinical relevance by the Goldman classification. Goldman class I and III were considered clinically relevant. Additionally, correlation with autopsy results and ante-mortem imaging was performed. Results: In total, 120 decedents were included and evaluated for unexpected findings on PMCT. Of them, 57 decedents also underwent an autopsy. A total of 1020 findings were identified; 111 correlated with the cause of death (10.9%), 508 were previously reported (49.8%), 99 were interpreted as post-mortem changes (9.7%), and 302 were classified as unexpected findings (29.6%). After correlation with autopsy (in 57 decedents), 24 clinically relevant unexpected findings remained. These findings were reported in 18 of 57 decedents (32%). Interestingly, 25% of all unexpected findings were not reported by autopsy. Conclusion: Many unexpected findings are reported by PMCT in hospitalized patients, a substantial portion of which is clinically relevant. Additionally, PMCT is able to identify pathology and injuries not reported by conventional autopsy. A combination of PMCT and autopsy can thus be considered a more comprehensive and complete post-mortem examination.

Introduction of postmortem CT increases the postmortem examination rate without negatively impacting the rate of traditional autopsy in daily practice: an implementation study

AIM

The aim of this implementation study was to assess the effect of postmortem CT (PMCT) and postmortem sampling (PMS) on (traditional) autopsy and postmortem examination rates. Additionally, the feasibility of PMCT and PMS in daily practice was assessed.

METHODS

For a period of 23 months, PMCT and PMS were used as additional modalities to the autopsy at the Department of Internal Medicine. The next of kin provided consent for 123 postmortem examinations. Autopsy rates were derived from the Dutch Pathology Registry, and postmortem examination rates were calculated for the period before, during and after the study period, and the exclusion rate, table time, time interval to informing the referring clinicians with results and the time interval to the Multidisciplinary Mortality Review Board (MMRB) meeting were objectified to assess the feasibility.

RESULTS

The postmortem examination rate increased (from 18.8% to 32.5%, p<0.001) without a decline in the autopsy rate. The autopsy rate did not change substantially after implementation (0.2% decrease). The exclusion rate was 2%, the table time was 23 min, and a median time interval of 4.1 hours between PMCT and discussing its results with the referring clinicians was observed. Additionally, more than 80% of the MMRB meetings were held within 8 weeks after the death of the patient.

CONCLUSIONS

Our study shows that the implementation of a multidisciplinary postmortem examination is feasible in daily practice and does not adversely affect the autopsy rate, while increasing the postmortem examination rate.

Pulmonary postmortem computed tomography of bacterial pneumonia and pulmonary edema in patients following non-traumatic in-hospital death

In this study, we compared the postmortem computed tomography (PMCT) findings among nonpathological lungs, lungs with bacterial pneumonia, and lungs with pulmonary edema in patients following non-traumatic in-hospital death. We studied 104 consecutive adult patients (208 lungs) who died in our tertiary care hospital and underwent PMCT and pathological autopsy (both within 2.5 days after death), and were pathologically diagnosed with nonpathological lungs, bacterial pneumonia, and pulmonary edema. Thirteen pulmonary features were assessed on the CT scans. We also examined the association between the time elapsed since death and the pulmonary findings. We observed increased lung opacities with horizontal plane formation, diffuse opacities, diffuse bronchovascular bundle thickening, symmetric opacities to the contralateral lung, and decreased segmental opacities with time elapsed since death (Cochran-Armitage test for trend). Multiple logistic regression revealed that the presence of opacities without horizontal plane formation or centrilobular opacities, and the absence of diffuse bronchovascular bundle thickening were associated with histopathological pneumonia, whereas the presence of opacities with horizontal plane formation, diffuse opacities, and interlobular septal thickening were associated with histopathological pulmonary edema. In conclusion, specific pulmonary PMCT findings increased with time elapsed since death, and some lung findings may facilitate the diagnosis of bacterial pneumonia and pulmonary edema.

Post-mortem computed tomography in adult non-suspicious death investigation-evaluation of an NHS based service

Objective:

Post-mortem CT (PMCT) can replace autopsy in many cases of non-suspicious death. A purely NHS-based service to replace autopsy with PMCT was launched, with the cost met by the family from 2015 to 2017, and subsequently “free at the point of delivery” after local authority funding was secured. The aim of the service was to improve the experience for the families. This report describes and evaluates the service against local standards of (1) less than four day turn around, (2) cause of death given in >90% and (3) less than 10% require autopsy.

Methods:

A retrospective review of reports, records and emails was undertaken to collate demographics, times of different stages of the process, the outcome and comments from service users.

Results:

Between July 2015 and July 2018, 279 patients had PMCT scans, 67 (24.0%) in the family-funded service and 212 (76%) in the current service. 97.1% (n = 271/279) of cases had the radiology report issued by day 3 (96.8% vs 98.6% for the family funded and local authority-funded services respectively). A cause of death was given in 97.2% of scans. 2.8% of patients required autopsy. Feedback from families, coroner’s officers and undertakers has been overwhelmingly positive.

Conclusion:

The services exceeded local standards and met the needs of the Coroner and the families based on the feedback received. This model could be employed for similar services, but the change to the logistics and financial structures required to initiate such services remains a significant hurdle.

Advances in knowledge:

This is the first report of a fully NHS-based PMCT service.

Forensic Radiology: A Primer

RATIONALE AND OBJECTIVE

Forensic radiology is a relatively unknown subspecialty which is becoming increasingly more important. The field incorporates antemortem and postmortem imaging for the detection and documentation of various pathologies for medicolegal purposes. Postmortem imaging is increasingly used in conjunction with the traditional autopsy in a process called a "virtual" autopsy. Radiography has been a staple of forensic investigations for over a century, first used in 1896. Advanced imaging techniques such as postmortem computed tomography and postmortem magnetic resonance imaging have only recently gained acceptance in the forensic science community. Postmortem computed tomography and postmortem magnetic resonance imaging methods are now widely used in some parts of the world, while other countries including the United States have been slower to adopt these methods into their daily practice. Advanced forensic imaging is increasingly used in the courts where juries have responded positively to such presentation of forensic data. For these reasons, advanced postmortem imaging is becoming a regular part of forensic investigations. The increase in the use of forensic imaging presents a unique opportunity for radiologists to collaborate with pathologists and law enforcement officials. This paper provides an overview of forensic radiology and identifies potential challenges and opportunities.

State of the art in post-mortem computed tomography: a review of current literature

Computed tomography (CT) and other advanced diagnostic imaging techniques are gaining popularity in forensic pathology. This paper aims to define and offer complete and easily accessible "state of the art" for post-mortem computed tomography (PMCT), by reviewing the latest international literature. The proposed format answers the "five Ws" that follows: (1) What: We report the different kinds of CT scan and settings generally used in post-mortem imaging. The machine most employed is a 8/16-slice spiral CT, usually without contrast enhancement. The introduction of some variables, such as CT-guided biopsies, post-mortem ventilation, and PMCT angiography is becoming increasingly useful. (2) Why: Literature highlights the many advantages of PMCT. Limitations can be partly overcome by modern imaging techniques and combined evaluation with traditional autopsy. (3) Who: Most authors agree that collaboration between different specialists, i.e., radiologists and pathologists, is the best scenario, since radiologic, anatomic, and forensic skills are needed simultaneously. The most important human factor is "teamwork". (4) When: Literature provides no absolute limits for performing PMCT. Some authors have tested PMCT as a replacement for conventional autopsy but found some limitations. Others evaluated PMCT as a guide or screening tool for traditional autopsy. (5) Where: Many research groups around the world have performed studies on the use of PMCT. Although few countries adopt PMCT in routine practice, its use is rapidly spreading.

State of the art in post-mortem forensic imaging in China

The autopsy and histopathologic examination are traditional and classic approaches in forensic pathology. In recent years, with the tremendous progresses of computer technology and medical imaging technology, the developed post-mortem computer tomography, post-mortem magnetic resonance imaging and other new methods provide non-invasive, intuitive, high-precision examining methods and research tools for the forensic pathology. As a result, the reconstruction of the injury as well as the analysis of injury mechanism has been essentially achieved. Such methods have become popular in the research field of forensic science and related work has also been carried out in China. This paper reviews the development and application of abovementioned post-mortem forensic imaging methods in China based on the relevant literature.

Forensic postmortem computed tomography: volumetric measurement of the heart and liver

PURPOSE

The purpose of this study was to investigate the utility of postmortem computed tomography (PMCT) images in estimating organ sizes and to examine the use of the cardiothoracic ratio (CTR).

METHODS

We included 45 individuals (19 females), who underwent a medico-legal autopsy. Using the computer software program Mimics^®, we determined in situ heart and liver volumes derived from linear measurements (width, height and depth) on a whole body PMCT-scan, and compared the volumes with ex vivo volumes derived by CT-scan of the eviscerated heart and liver. The ex vivo volumes were also compared with the organ weights. Further, we compared the CTR with the ex vivo heart volume and a heart weight-ratio (HWR). Intra- and inter-observer analyses were performed.

RESULTS

We found no correlation between the in situ and ex vivo volumes of the heart and liver. However, a highly significant correlation was found between the ex vivo volumes and weights of the heart and liver. No correlations between CTR and the ex vivo heart volume nor with HWR was found. Concerning cardiomegaly, we found no agreement between the CTR and HWR. The intra- and inter-observer analyses showed no significant differences.

CONCLUSIONS

Noninvasive in situ PMCT methods for organ measuring, as performed in this study, are not useful tools in forensic pathology. The best method to estimate organ volume is a CT-scan of the eviscerated organ. PMCT-determined CTR seems to be useless for ascertaining cardiomegaly, as it neither correlated with the ex vivo heart volume nor with the HWR.

Non-invasive or minimally invasive autopsy compared to conventional autopsy of suspected natural deaths in adults: a systematic review

OBJECTIVES

Autopsies are used for healthcare quality control and improving medical knowledge. Because autopsy rates are declining worldwide, various non-invasive or minimally invasive autopsy methods are now being developed. To investigate whether these might replace the invasive autopsies conventionally performed in naturally deceased adults, we systematically reviewed original prospective validation studies.

MATERIALS AND METHODS

We searched six databases. Two reviewers independently selected articles and extracted data. Methods and patient groups were too heterogeneous for meaningful meta-analysis of outcomes.

RESULTS

Sixteen of 1538 articles met our inclusion criteria. Eight studies used a blinded comparison; ten included less than 30 appropriate cases. Thirteen studies used radiological imaging (seven dealt solely with non-invasive procedures), two thoracoscopy and laparoscopy, and one sampling without imaging. Combining CT and MR was the best non-invasive method (agreement for cause of death: 70 %, 95%CI: 62.6; 76.4), but minimally invasive methods surpassed non-invasive methods. The highest sensitivity for cause of death (90.9 %, 95%CI: 74.5; 97.6, suspected duplicates excluded) was achieved in recent studies combining CT, CT-angiography and biopsies.

CONCLUSION

Minimally invasive autopsies including biopsies performed best. To establish a feasible alternative to conventional autopsy and to increase consent to post-mortem investigations, further research in larger study groups is needed.

KEY POINTS

• Health care quality control benefits from clinical feedback provided by (alternative) autopsies. • So far, sixteen studies investigated alternative autopsy methods for naturally deceased adults. • Thirteen studies used radiological imaging modalities, eight tissue biopsies, and three CT-angiography. • Combined CT, CT-angiography and biopsies were most sensitive diagnosing cause of death.

Ventilated postmortem computed tomography in children: feasibility and initial experience

OBJECTIVES

Ventilated postmortem computed tomography (vPMCT) is associated with improved pulmonary imaging compared to standard PMCT in adults. We aimed to evaluate the feasibility of performing ventilated PMCT in children.

METHODS

Postmortem thoracic CT was performed before (PMCT) and after ventilation (vPMCT). We used a range of mouthpieces, including endotracheal tubes, bag and mask and laryngeal mask airway (LMA). Hounsfield units of the lungs at PMCT were measured for normal and abnormal lung areas, before and after ventilation. All patients underwent full conventional autopsy and histology.

RESULTS

Twelve patients underwent ventilated PMCT, median age 52 days (range 3-304 days). Ventilated PMCT provided diagnostic lung images in all 12 cases, compared to only three unventilated PMCT examinations (p < 0.005). In all cases, ventilated PMCT improved the image quality of aerated lungs irrespective of the method used. Average lung Hounsfield units decreased significantly with ventilation from pre-vPMCT values (-134.1 ± 215.1 vs post-vPMCT -531.8 ± 190.1; p < 0.001). LMA with continuous positive pressure ventilation subjectively provided the best results.

CONCLUSION

Ventilated PMCT significantly improves lung aeration in children and can aid recognition of areas of abnormality in paediatric lungs. Such advances will improve accuracy and uptake of imaging-assisted autopsies in children.