Zabiullah Ali

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.

Comparison of whole-body post mortem 3D CT and autopsy evaluation in accidental blunt force traumatic death using the abbreviated injury scale classification

Although 3D CT imaging data are available on survivors of accidental blunt trauma, little similar data has been collected and classified on major injuries in victims of fatal injuries. This study compared the sensitivity of post mortem computed tomography (PMCT) with that of conventional autopsy for major trauma findings classified according to the trauma Abbreviated Injury Scale (AIS). Whole-body 3D PMCT imaging data and full autopsy findings were analyzed on 21 victims of accidental blunt force trauma death. All major injuries were classified on the AIS scale with ratings from 3 (serious) to 6 (unsurvivable). Agreement between sensitivity of autopsy and PMCT for major injuries was determined. A total of 195 major injuries were detected (mean per fatality, 9.3; range, 1-14). Skeletal injuries by AIS grade included 37 grade 3, 45 grade 4, 12 grade 5, and 2 grade 6 major findings. Soft tissue injuries included 10 grade 3, 68 grade 4, 16 grade 5, and 5 grade 6 major findings. Of these, PMCT detected 165 (88 skeletal, 77 soft tissue), and autopsy detected 127 (59 skeletal, 68 soft tissue). PMCT agreed with autopsy in 86% and 76% of skeletal and soft tissue injuries, respectively. PMCT detected an additional 37 skeletal and 31 soft tissue injuries that were not identified at autopsy. Autopsy detected 8 skeletal and 22 soft tissue injuries that were not detected by PMCT. PMCT was more sensitive for skeletal (P=0.05) and head and neck region injury (P=0.043) detection. PMCT showed a trend for greater sensitivity than autopsy, but this did not reach statistical significance (P=0.083). 3D PMCT detected significantly more skeletal injuries than autopsy and a similar number of soft tissue injuries to autopsy and promises to be a sensitive tool for detection and classification of skeletal injuries in fatal blunt force accidental trauma. Use of the AIS scale allows standardized categorization and quantification of injuries that contribute to death in such cases and allows more objective comparison between autopsy and PMCT.

Diabetic ketoacidosis: a silent death.

AbstractDiabetic ketoacidosis (DKA) results from severe insulin deficiency and can be diagnosed at autopsy despite no known history of the disease. Diabetic ketoacidosis may be the initial manifestation of type 1 diabetes or may result from increased insulin requirement in type 1 diabetic patients. The purpose of this study was to determine the percentage of DKA death investigated by the Office of Chief Medical Examiner that was not associated with a known history of diabetes.Cases investigated by the Office of Chief Medical Examiner during a 6-year period whose cause of death was DKA were identified using a centralized database. To determine the percentage with known history of diabetes, investigation reports were reviewed for any documentation of this history. The toxicology reports of all DKA deaths were reviewed together with histologic slides, if available, for possible microscopic changes. Concentrations of vitreous glucose, vitreous acetone, and blood acetone were used to diagnose DKA in these autopsied cases.Nearly a third of all death from DKA (32 of 92 during a 6-year period) occurred in individuals who had no known history of diabetes, emphasizing the importance of regular physicals that include a check of glucose concentration, and especially if any warning signs are present. In a case of sudden death, it is recommended that the volatile toxicology analysis at a medical examiner’s office should include tests for acetone concentration, which when elevated, together with an elevated vitreous glucose, indicates DKA.

Case report of a fatal intoxication by Nucynta.

AbstractTapentadol (Nucynta) is a centrally acting opioid analgesic prescribed for the treatment of moderate to severe acute pain. Its efficacy is believed to be due to &mgr;-opioid receptor agonist activity and inhibition of norepinephrine reuptake resulting in increased norepinephrine concentrations. There is only one other case in the literature relating to the toxicity of this agent or report of a fatality. This case report documents a case in which tapentadol was identified as the cause of death. The tapentadol concentration found in the heart blood submitted in this case was more than 20 times the upper limit of the therapeutic range. Possible mechanisms of death include respiratory depression, central nervous system depression, and serotonin syndrome. Based on the scene investigation and autopsy findings in this case, the medical examiner determined that the cause of death was narcotic (Nucynta) intoxication and the manner of death was undetermined.

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.

Generalized arterial calcification of infancy—Findings at post-mortem computed tomography and autopsy

Generalized arterial calcification in infancy is a rare genetic disorder characterized by abnormal calcification of large and medium sized arteries and marked myointimal proliferation resulting in arterial stenosis. The condition is often fatal secondary to complications of cardiac ischemia, hypertension and cardiac failure. In this report we describe the findings at post mortem computed tomography, histology and autopsy.

The First Use of Postmortem 3D Computed Tomography Images as Evidence in U.S. Criminal Courts: A Report of Four Cases

Computed tomography (CT) is an imaging technique that has assumed an increasingly important role in clinical medicine since its invention in 1972 and has been admissible as evidence in court for many years. A recently introduced scientific application of CT, enabled by major advances in high-resolution imaging, postmortem CT (PMCT) allows unprecedented three-dimensional (3D) visualization of the whole body after death. As a novel scientific tool, PMCT may be subject to scrutiny for admissibility in court under Federal Rule of Evidence 702 and the Daubert standard. We present four cases of criminal prosecution for vehicular manslaughter where PMCT, including images generated with 3D reconstruction techniques, was admitted as evidence to demonstrate victim injuries to the jury in 2012. The use of PMCT for demonstrative proposes in court enabled the triers of fact to better understand and visualize injuries allegedly caused by the accused. Not only is PMCT a useful forensic tool, but it may also provide powerful and easily comprehensible visual evidence before a judge or jury. These cases may be used as precedent for future testimony in U.S. courts.

Estimating Sex Using Metric Analysis of the Scapula by Postmortem Computed Tomography

Postmortem computed tomography (CT) has been extensively used in the last decade for identification purposes and in various anthropologic studies. Postmortem CT measurements of scapulae, analyzed using logistic discriminant function developed in this study, showed 94.5% accuracy in estimating sex. Data analyzed using the Dabbs and Moore‐Jansen (2010) discriminant function and the discriminant function generated in this study provided nearly identical results with disagreement in only one case. Height and weight were not statically significant in sex prediction. The results of this study show that data obtained from volume rendered postmortem CT images can be considered reliable and treated as a practical option to standard anthropological methods, especially in mass fatalities as a rapid triage tool for sex determination.

Quantitative measurement of lipid rich plaque by coronary computed tomography angiography: A correlation of histology in sudden cardiac death

BACKGROUND AND AIMS Recent advancements in coronary computed tomography angiography (CCTA) have allowed for the quantitative measurement of high-risk lipid rich plaque. Determination of the optimal threshold for Hounsfield units (HU) by CCTA for identifying lipid rich plaque remains unknown. We aimed to validate reliable cut-points of HU for quantitative assessment of lipid rich plaque. METHODS 8 post-mortem sudden coronary death hearts were evaluated with CCTA and histologic analysis. Quantitative plaque analysis was performed in histopathology images and lipid rich plaque area was defined as intra-plaque necrotic core area. CCTA images were analyzed for quantitative plaque measurement. Low attenuation plaque (LAP) was defined as any pixel < 30, 45, 60, 75, and 90 HU cut-offs within a coronary plaque. The area of LAP was calculated in each cross-section. RESULTS Among 105 cross-sections, 37 (35.2%) cross-sectional histology images contained lipid rich plaque. Although the highest specificity for identifying lipid rich plaque was shown with <30 HU cut-off (88.2%), sensitivity (e.g. 55.6% for <75 HU, 16.2% for <30 HU) and negative predictive value (e.g. 75.9% for <75 HU, 65.9% for <30 HU) tended to increase with higher HU cut-offs. For quantitative measurement, <75 HU showed the highest correlation coefficient (0.292, p = 0.003) and no significant differences were observed between lipid rich plaque area and LAP area between histology and CT analysis (Histology: 0.34 ± 0.73 mm2, QCT: 0.37 ± 0.71 mm2, p = 0.701). CONCLUSIONS LAP area by CCTA using a <75 HU cut-off value demonstrated high sensitivity and quantitative agreement with lipid rich plaque area by histology analysis.

En Bloc Examination of the Neck in Pediatric Homicide Cases: A Proper Way for Complete Assessment of Neck Trauma

The necks of infants and young children are not only anatomically different from adults, but are also supported by much weaker musculoskeletal systems and are therefore prone to trauma as a result of extension/flexion (shaking) or contact trauma to the head. Shaking cervical spine injuries can occur at much lower levels of head velocity and acceleration than those reported for shaken baby syndrome. The proper method for a comprehensive and detailed examination of the neck in pediatric homicide and suspected homicide cases is the en bloc examination of the neck, because the standard examination of the spinal cord not only distorts the anatomical relationship of the cord and osteocartilagenous structures, but also excludes the cervical nerves, ganglia, and the vertebral arteries from being evaluated. Interpretation of gross and microscopic findings using this method requires experience and knowledge of the anatomical relationship and common artifacts, such as epidural, focal intradural, or even isolated nerve hemorrhage to avoid misinterpretation. It is our opinion that this method should be applied to all pediatric homicide or suspected homicide cases, but is not suited for routine or nonsuspicious cases as it will add to the time and cost of medical examiners operations.