David Fowler

Accuracy and reliability of measurements obtained from computed tomography 3D volume rendered images

Forensic pathologists commonly use computed tomography (CT) images to assist in determining the cause and manner of death as well as for mass disaster operations. Even though the design of the CT machine does not inherently produce distortion, most techniques within anthropology rely on metric variables, thus concern exists regarding the accuracy of CT images reflecting an objects true dimensions. Numerous researchers have attempted to validate the use of CT images, however the comparisons have only been conducted on limited elements and/or comparisons were between measurements taken from a dry element and measurements taken from the 3D-CT image of the same dry element. A full-body CT scan was performed prior to autopsy at the Office of the Chief Medical Examiner for the State of Maryland. Following autopsy, the remains were processed to remove all soft tissues and the skeletal elements were subject to an additional CT scan. Percent differences and Bland-Altman plots were used to assess the accuracy between osteometric variables obtained from the dry skeletal elements and from CT images with and without soft tissues. An additional seven crania were scanned, measured by three observers, and the reliability was evaluated by technical error of measurement (TEM) and relative technical error of measurement (%TEM). Average percent differences between the measurements obtained from the three data sources ranged from 1.4% to 2.9%. Bland-Altman plots illustrated the two sets of measurements were generally within 2mm for each comparison between data sources. Intra-observer TEM and %TEM for three observers and all craniometric variables ranged between 0.46mm and 0.77mm and 0.56% and 1.06%, respectively. The three-way inter-observer TEM and %TEM for craniometric variables was 2.6mm and 2.26%, respectively. Variables that yielded high error rates were orbital height, orbital breadth, inter-orbital breadth and parietal chord. Overall, minimal differences were found among the data sources and high accuracy was noted between the observers, which prove CT images are an acceptable source to collect osteometric variables.

Death in custody: a historical analysis

Abstract:  This research delineates the historical evolution of death in custody. A retrospective, exploratory analysis of 145,425 cases from Maryland’s Office of the Chief Medical Examiner, occurring from 1939 to 2004, was conducted. Two hundred and two custodial deaths were identified and subsequently examined relative to time, agency, decedent characteristics, and cause and manner of death. Results indicate that there have been substantive changes in custodial deaths over time. Cardiovascular disease was the most frequent cause of death from the 1930s to the 1970s, except for the 1940s, when syphilis and tuberculosis took precedence. Asphyxia, the predominant cause of death in the 1980s, reflected an increase in suicidal hangings. Emerging in the 1980s, drug intoxication deaths were prevalent in the 1990s and 2000s. Sudden unexplained deaths involving violent behavior, the use of multiple restraints, and drug intoxication were not identified until the 1980s, coinciding with periods of increased cocaine abuse nationally.

Organ weight effects of drowning and asphyxiation on the lungs, liver, brain, heart, kidneys, and spleen.

An examination of the organ weights associated with victims of drowning, asphyxiation and trauma was undertaken to determine (a) the effects of asphyxiation compared to a trauma group, and in turn, (b) the effects of drowning compared to an asphyxiation group. Included in the study were 217 drowning deaths, 166 pure asphyxiation deaths and 381 trauma deaths. The effects of asphyxiation (compared to trauma) resulted in elevated mean organ weights for the lungs, liver, kidneys and spleen (with mean increases of 17.8, 10.5, 10.3 and 23.4%, respectively). Effects of drowning (compared to asphyxiation) resulted in elevated mean organ weights only with the lungs and kidneys (with mean increases of 30.0 and 4.4%, respectively). Only the mean heart and brain weight remained constant across all experimental groups. A picture of drowning is suggested in which elevated lung and kidney weights are the result of both asphyxiation and the aspiration of water that occurs with drowning, whereas elevated spleen and liver weights in drowning victims are associated with only the effects of asphyxiation. In addition, the common autopsy finding of a small, anemic spleen in drowning, rather than caused by some pathophysiological mechanism of death, is hypothesized to be a postmortem phenomenon.

Concentration of Carbon Monoxide (CO) in Postmortem Human Tissues: Effect of Environmental CO Exposure*

ABSTRACT: We studied how carbon monoxide (CO) is distributed within the human body through quantitation of CO concentrations in postmortem tissue samples from fatalities including possible CO exposure. Stored, frozen tissues were diced, sonicated in water, and 0.01–8.0 mg wet weight (ww) tissues were incubated with sulfosalicylic acid in CO‐purged, septum‐sealed vials. CO released into the headspace was quantitated by reduction gas chromatography. Mean tissue CO concentrations (pmol/mg ww) from subjects diagnosed to have no known CO exposure (control, N=14), died from fire (N=13), and CO asphyxiation (N=7), respectively, were: adipose (2;13;9), brain (3;13;65), muscle (15;97;297), heart (30;99;371), kidney (22;432;709, lung (54;690;2638), spleen (73;1366;3548), and blood (162;2238;5070). Carboxyhemoglobin concentrations were 1.4%, 25.2%, and 69.1% of total hemoglobin, respectively. We conclude that measurements of CO concentration in a variety of tissues can be used as markers for the degree of exogenous CO exposure and the identification of possible causes of death.

Erratum to ¿Organ weight effects of drowning and asphyxiation on the lungs, liver, brain, heart, kidneys, and spleen¿ [Forensic Sci. Int. 133 (2003) 190¿196]

Abstract An examination of the organ weights associated with victims of drowning, asphyxiation and trauma was undertaken to determine (a) the effects of asphyxiation compared to a trauma group, and in turn, (b) the effects of drowning compared to an asphyxiation group. Included in the study were 217 drowning deaths, 166 pure asphyxiation deaths and 381 trauma deaths. The effects of asphyxiation (compared to trauma) resulted in elevated mean organ weights for the lungs, liver, kidneys and spleen (with mean increases of 17.8, 10.5, 10.3 and 23.4%, respectively). Effects of drowning (compared to asphyxiation) resulted in elevated mean organ weights only with the lungs and kidneys (with mean increases of 30.0 and 4.4%, respectively). Only the mean heart and brain weight remained constant across all experimental groups. A picture of drowning is suggested in which elevated lung and kidney weights are the result of both asphyxiation and the aspiration of water that occurs with drowning, whereas elevated spleen and liver weights in drowning victims are associated with only the effects of asphyxiation. In addition, the common autopsy finding of a small, anemic spleen in drowning, rather than caused by some pathophysiological mechanism of death, is hypothesized to be a postmortem phenomenon.

Recurrent cerebral venous thrombosis associated with heterozygote methylenetetrahydrofolate reductase C677T mutation and sickle cell trait without homocysteinemia: An autopsy case report and review of literature

Elevated blood homocysteine concentration and certain genetic mutations have been associated with increased risk for developing arterial and venous thrombosis. A common mutation of methylenetetrahydrofolate reductase, MTHFR C677T, has been associated with elevated homocysteine concentration and increased risk for developing thrombosis in homozygote carriers. Heterozygote carriers for this gene mutation, if associated with other major or minor risk factors for thrombophilia, appear to be prone to develop thrombosis. A postmortem genetic testing for common mutations resulting in thrombophilia should be performed in all individuals who die as a result of thrombosis, regardless of predisposing risk factors, to determine the true prevalence of mutations in these individuals, and to assess the true role of a certain mutation, such as heterozygote MTHFR C677T, in the pathogenesis of thrombosis. Postmortem genetic testing for common mutations associated with thrombophilia in selected cases has potentially life-saving importance to surviving family members. We report a case of recurrent cerebral venous thrombosis in a 19 year old male with history of sickle cell trait, obesity, and high normal blood homocysteine, who was heterozygote for MTHFR C677T mutation.

Rat Bite Fever, a Fatal Case of Streptobacillus moniliformis Infection in a 14‐Month‐Old Boy

Abstract:  Streptobacillus moniliformis is the primary cause of rat bite fever in North America. Children under 12 years of age are primarily infected, presenting with an acute syndrome of fever, rash, and polyarthritis. Common vectors include rats and mice. Transmission is predominantly from a bite or scratch, but contact with or ingestion of food contaminated with feces or saliva has also been reported. We report a fatal case of S. moniliformis infection in a 14‐month‐old‐boy. At home, the child was exposed to filthy living conditions and the family had pet ferrets. Autopsy revealed a red‐pink, mostly confluent rash and a circumscribed area suspicious for a possible bite mark. Cerebrospinal fluid cultures were positive for S. moniliformis. This case highlighted key features, such as the morbiliform rash, but lacked lymphadenopathy or joint manifestations. It is important to consider rat or rodent exposure as a source of infection.

Interaction between carbon monoxide and ethanol in fire fatalities

Impairment due to ethanol is clearly a risk factor in deaths due to fire. However, it is less clear whether there is a physiological interaction between ethanol and carbon monoxide (CO) that would alter the carboxyhemoglobin saturation level (COHb sat.) that accounts for death. In an attempt to explore this issue further, 196 fire fatalities investigated by the Office of the Chief Medical Examiner, State of Maryland over a 3-year period were examined. COHb sat. and blood ethanol concentrations (BAC) were tabulated. Twelve cases positive for therapeutic or abused drugs other than lidocaine or atropine were excluded; 184 cases were included. The data indicate that ethanol does not affect the COHb sat. that accounts for death, since the percentage of cases positive for ethanol at a given COHb range shows no trends. Therefore, we conclude that although ethanol remains a risk factor in fire fatalities, the risk appears to be related to the impairment that it produces as opposed to a direct interaction with CO.

Failure to detect elevated levels of carboxyhemoglobin in infants dying from SIDS.

Carboxyhemoglobin (COHb) levels were determined in stored blood samples from 91 infants diagnosed to have died from the sudden infant death syndrome (SIDS) (0.59+/-0.41%, excluding one outlying value of 10.83%); 48 age-matched controls (0.53+/-0.38%); and three individuals who died from fire related causes (41+/-20%). No statistical differences in COHb levels were detected between blood from SIDS and control infants (p = 0.43).

A Comparison of Carboxyhemoglobin Saturation Values in Postmortem Heart Blood and Peripheral Blood Specimens

The following is a study conducted to determine whether there was any significant difference in carboxyhemoglobin (COHb) saturation levels between the heart blood and blood collected from a peripheral site. The average heart blood to peripheral blood COHb saturation level ratio in the 42 cases studied was 1.09. Sixty-two percent (26 of 42) of the cases had a heart blood to peripheral blood ratio between 0.9 and 1.1; 74% (31 of 42) had a ratio between 0.8 and 1.2. Eighty-three percent (35 of 42) had a ratio between 0.7 and 1.3. There were four cases where the heart blood to peripheral blood ratio was either below 0.6 or greater than 1.4. The differences between the two sites were not statistically significant.