Mike Biggs

The role of micro-computed tomography in forensic investigations☆

The use of micro-CT within forensic practice remains an emerging technology, principally due to its current limited availability to forensic practitioners. This review provides those with little or no previous experience of the potential roles of micro-CT in forensic practice with an illustrated overview of the technology, and the areas of practice in which micro-CT can potentially be applied to enhance forensic investigations.

Post-mortem computed tomography ventilation; simulating breath holding

Whilst the literature continues to report on advances in the use of post-mortem computed tomography (PMCT), particularly in relation to post-mortem angiography, there are few papers published that address the diagnostic problems related to post-mortem changes in the lungs and ventilation. We present a development of previous methods to achieve ventilated PMCT (VPMCT). We successfully introduced a supraglottic airway in 17/18 cases without causing overt damage, despite rigor mortis. Using a clinical portable ventilator, we delivered continuous positive airway pressure to mimic clinical breath-hold inspiratory scans. This caused significant lung expansion and a reduction in lung density and visible normal post-mortem changes. All thoracic pathology identified at autopsy, including pneumonia, was diagnosed on VPMCT in this small series. This technique provides a rapid form of VPMCT, which can be used in both permanent and temporary mortuaries, allowing for the post-mortem radiological comparison of pre-ventilation and post-ventilation images mimicking expiratory and inspiratory phases. We believe that it will enhance the diagnostic ability of PMCT in relation to lung pathology.

Diagnostic accuracy of post-mortem CT with targeted coronary angiography versus autopsy for coroner-requested post-mortem investigations: a prospective, masked, comparison study

Summary Background England and Wales have one of the highest frequencies of autopsy in the world. Implementation of post-mortem CT (PMCT), enhanced with targeted coronary angiography (PMCTA), in adults to avoid invasive autopsy would have cultural, religious, and potential economic benefits. We aimed to assess the diagnostic accuracy of PMCTA as a first-line technique in post-mortem investigations. Methods In this single-centre (Leicester, UK), prospective, controlled study, we selected cases of natural and non-suspicious unnatural death referred to Her Majestys (HM) Coroners. We excluded cases younger than 18 years, known to have had a transmittable disease, or who weighed more than 125 kg. Each case was assessed by PMCTA, followed by autopsy. Pathologists were masked to the PMCTA findings, unless a potential risk was shown. The primary endpoint was the accuracy of the cause of death diagnosis from PMCTA against a gold standard of autopsy findings, modified by PMCTA findings only if additional substantially incontrovertible findings were identified. Findings Between Jan 20, 2010, and Sept 13, 2012, we selected 241 cases, for which PMCTA was successful in 204 (85%). Seven cases were excluded from the analysis because of procedural unmasking or no autopsy data, as were 24 cases with a clear diagnosis of traumatic death before investigation; 210 cases were included. In 40 (19%) cases, predictable toxicology or histology testing accessible by PMCT informed the result. PMCTA provided a cause of death in 193 (92%) cases. A major discrepancy with the gold standard was noted in 12 (6%) cases identified by PMCTA, and in nine (5%) cases identified by autopsy (because of specific findings on PMCTA). The frequency of autopsy and PMCTA discrepancies were not significantly different (p=0·65 for major discrepancies and p=0·21 for minor discrepancies). Cause of death given by PMCTA did not overlook clinically significant trauma, occupational lung disease, or reportable disease, and did not significantly affect the overall population data for cause of death (p≥0·31). PMCTA was better at identifying trauma and haemorrhage (p=0·008), whereas autopsy was better at identifying pulmonary thromboembolism (p=0·004). Interpretation For most sudden natural adult deaths investigated by HM Coroners, PMCTA could be used to avoid invasive autopsy. The gold standard of post-mortem investigations should include both PMCT and invasive autopsy. Funding National Institute for Health Research.

Coronary optical coherence tomography: minimally invasive virtual histology as part of targeted post-mortem computed tomography angiography

Social, cultural and practical barriers to conventional invasive autopsy have led to considerable interest in the development of minimally invasive radiological techniques as an alternative to the invasive autopsy for determining the cause of death. Critical to accurate diagnosis in this context is detailed examination of coronary anatomy and pathology. Current computed tomography and magnetic resonance imaging approaches have significantly advanced minimally invasive autopsy practice but have limited spatial resolution. This prohibits assessment at a microscopic level, meaning that histological assessment is still required for detailed analysis of, for example, coronary plaque rupture or dissection. Coronary optical coherence tomography (OCT) is used in the living during percutaneous coronary interventions to provide high-resolution coronary imaging, but this technique for obtaining virtual histology has not, to date, been translated into minimally invasive autopsy practice. We present a first description of minimally invasive post-mortem coronary OCT and discuss the potential for this technique to advance current practice.

Can cause of death be predicted from the pre-necropsy information provided in coroners’ cases?

Aim: To determine whether the cause of death can be accurately predicted from the pre-necropsy information available in coroners’ cases, before carrying out a postmortem examination. Methods: In this prospective study pathologists read the clinical summary provided by the Coroner’s Office and formulated a predicted cause of death. An external examination was then conducted and any relevant information recorded, together with any changes to the original predicted cause of death. They then carried out a complete necropsy before recording a final cause of death, which was subsequently compared with their prediction. Results: A total of 95 necropsies were included in the study. The cause of death was deemed to have been correctly predicted from the history in 62 cases (65.3%). In 33 cases (34.7%) an unexpected cause of death was found. Findings from the external examination were noteworthy in only 8 cases (8.4%), and did not alter the cause of death in any case. Conclusions: In certain circumstances an accurate cause of death may be given with confidence without the apparent need for necropsy. However, many common causes of death can present with similar or misleading scenarios. This study indicates that performing necropsies, despite seemingly predictable circumstances, is advisable if an accurate cause of death is to be recorded.

Online survey of current autopsy practice

Aims: The Royal College of Pathologists (RCPath) has for several years published guidance on good autopsy practice. However, pressures such as time, cost and the introduction of the Human Tissue Act have generated suggestions that there is a discrepancy between the published guidelines and what can realistically be achieved in daily practice. The aims of this study were to determine the extent to which practising pathologists agree with this complaint, and what suggestions they might have for its resolution. Methods: All histopathologists in the UK on the RCPath database (n = 1213) were sent an email invitation to participate in an online questionnaire. Results: 406 pathologists completed the survey, providing numerical data and free-text responses. Results concerning pressures of time, resources and limitations on examination and sampling were in keeping with those expected from recent issues raised. The view that RCPath guidelines are higher than can be achieved in routine coronial autopsy practice was widely supported, but only 45% stated that the RCPath should publish separate guidelines to differentiate between hospital (“consent”) autopsies and medico-legal cases. Conclusion: The circumstances under which coronial autopsies are conducted in many parts of the UK make it difficult or impossible to comply with current RCPath guidance. Pathologists disagree on whether this situation demands a reduction of RCPath standards, an improvement in autopsy practice in medico-legal cases to current RCPath standards, or the implementation of “double standards”. Resolution of this dilemma requires clarification of exactly what a coronial autopsy is trying to achieve.

End-tidal CO2 detection during cadaveric ventilation.

‘Life like’ end-tidal CO2 production has been reported in frozen cadaver during intubation training. We report the same phenomenon in a non-frozen cadaveric model used to undertake CT postmortem, with the additional findings of an increase in CO2 with chest compressions and an increase in CO2 after a pause in ventilation.

Detection of bacterioplankton using PCR probes as a diagnostic indicator for drowning; the Leicester experience

Bodies found immersed in water can pose difficulties to the investigating authorities. Pathologists may be assisted with the diagnosis by the use of tests such as the analysis for diatoms or the levels of strontium in the blood, although there is a recognised level of uncertainty associated with these tests. Recent work from Japan has shown that using molecular approaches, most recently real-time polymerase chain reaction (PCR) assays with TaqMan probes for bacterioplankton, it is possible to undertake rapid, less laborious, high throughput tests to differentiate freshwater from marine bacterioplankton and in doing so provide a molecular diagnostic test to assist in the diagnosis of drowning. We report the experiences of a United Kingdom forensic pathology unit in the use of this PCR based system for the diagnosis of drowning. We applied this technique to 20 adult and child cadavers from 4 bath, 12 freshwater, 2 brackish and 2 salt water scenes both from within the United Kingdom and abroad. Drowning was concluded to be the cause of death in 16 of these 20 cases and the PCR method supported this conclusion in 12 of these 16 cases. The PCR did not provide evidence of drowning in the four cases where death was from other causes. We illustrate that this PCR method provides a rapid diagnostic supportive test for the diagnosis of drowning that can be applied to United Kingdom autopsy practice.

Myocardial Bridging: Is it Really a Cause of Sudden Cardiac Death?

Myocardial bridges are described as myocardial muscle fibre bundles covering an epicardial coronary artery for a variable distance. They are a relatively common finding, with incidence changing on the basis of the study method used (angiographic/necropsy). Although myocardial bridges are usually associated with a benign prognosis, being in many cases asymptomatic and found only by chance, their presence has also been considered a cause of angina, malignant arrhythmia, myocardial infarction and sudden death. They are diagnosed by angiography in vivo when systolic compression of a segment of coronary artery that remains patent during diastole is observed. Whether or not myocardial bridges are benign or of pathological significance is the subject of ongoing controversy. Arguments and evidence for and against this phenomenon are discussed here, and a potential solution is offered in an attempt to clarify the situation.

Mammography in symptomatic women attending a rapid diagnosis breast clinic: a prospective study.

INTRODUCTION We determined whether it is safe to avoid mammograms in a group of symptomatic women with a non-suspicious history and clinical examination. PATIENTS AND METHODS Symptomatic women aged 35 years or over newly referred to a rapid-diagnosis breast clinic underwent mammography on arrival in the clinic. A breast radiologist reported on the mammograms. An experienced clinician who was unaware of the mammogram findings examined patients and decided whether a mammogram was indicated or not. If not, a management plan was formulated. Mammogram findings were then provided to the clinician and any change to the original management plan as a result of mammography was recorded. RESULTS In two-thirds (67%) of 218 patients, the clinician felt a mammogram was indicated. Half (46%) of these mammograms showed an abnormality; of these abnormal mammograms, 41% were breast cancer. Among the third (n = 71) of mammograms felt not to be indicated, 3 showed abnormalities of which 2 were breast cancer. One cancer was not suspected clinically or mammographically but was diagnosed on cyto/histopathological assessment. CONCLUSIONS A significant proportion of patients attending a symptomatic breast clinic have a non-suspicious history and normal clinical findings on examination. However, even in this group avoiding mammograms risks missing clinically occult breast cancers. It would appear sensible to offer mammograms to all symptomatic women over 35 years of age.