Gary M. Hatch

Suicide Announcement on Facebook

BACKGROUND The media and the Internet may be having an influence on suicidal behavior. Online social networks such as Facebook represent a new facet of global information transfer. The impact of these online social networks on suicidal behavior has not yet been evaluated. AIMS To discuss potential effects of suicide notes on Facebook on suicide prevention and copycat suicides, and to create awareness among health care professionals. METHODS We present a case involving a suicide note on Facebook and discuss potential consequences of this phenomenon based on literature found searching PubMed and Google. RESULTS There are numerous reports of suicide notes on Facebook in the popular press, but none in the professional literature. Online social network users attempted to prevent planned suicides in several reported cases. To date there is no documented evidence of a copycat suicide, directly emulating a suicide announced on Facebook. CONCLUSIONS Suicide notes on online social networks may allow for suicide prevention via the immediate intervention of other network users. But it is not yet clear to what extent suicide notes on online social networks actually induce copycat suicides. These effects deserve future evaluation and research.

You Can’t Touch This: Touch-free Navigation Through Radiological Images

Keyboards, mice, and touch screens are a potential source of infection or contamination in operating rooms, intensive care units, and autopsy suites. The authors present a low-cost prototype of a system, which allows for touch-free control of a medical image viewer. This touch-free navigation system consists of a computer system (IMac, OS X 10.6 Apple, USA) with a medical image viewer (OsiriX, OsiriX foundation, Switzerland) and a depth camera (Kinect, Microsoft, USA). They implemented software that translates the data delivered by the camera and a voice recognition software into keyboard and mouse commands, which are then passed to OsiriX. In this feasibility study, the authors introduced 10 medical professionals to the system and asked them to re-create 12 images from a CT data set. They evaluated response times and usability of the system compared with standard mouse/keyboard control. Users felt comfortable with the system after approximately 10 minutes. Response time was 120 ms. Users required 1.4 times more time to re-create an image with gesture control. Users with OsiriX experience were significantly faster using the mouse/keyboard and faster than users without prior experience. They rated the system 3.4 out of 5 for ease of use in comparison to the mouse/keyboard. The touch-free, gesture-controlled system performs favorably and removes a potential vector for infection, protecting both patients and staff. Because the camera can be quickly and easily integrated into existing systems, requires no calibration, and is low cost, the barriers to using this technology are low.

The influence of body temperature on image contrast in post mortem MRI

OBJECTIVE To assess the temperature dependency of tissue contrast on post mortem magnetic resonance (PMMR) images both objectively and subjectively; and to visually demonstrate the changes of image contrast at various temperatures. MATERIALS AND METHODS The study was approved by the responsible justice department and the ethics committee. The contrast of water, fat, and muscle was measured using regions of interest (ROI) in the orbit of 41 human corpses to assess how body temperature (range 2.1-39.8 °C) relates to image contrast of T1-weighted (T1W) and T2-weighted (T2W) sequences on PMMR. Regressions were calculated using the method of least squares. Three readers judged visible changes of image contrast subjectively by consensus. RESULTS There was a positive relationship between temperature and contrast on T1-weighted (T1W) images and between temperature and the contrast of fat/muscle on T2-weighted (T2W) images. There was a negative relationship between temperature and the contrast of water/fat and water/muscle on T2W images. Subjectively, the influence of temperature became visible below 20 °C on T2W images, and below 10 °C on T1W images. CONCLUSION Image contrast on PMMR depends on the temperature of a corpse. Radiologists involved in post mortem imaging must be aware of temperature-related changes in MR image contrast. To preserve technical quality, scanning corpses below 10 °C should be avoided.

Radiologic identification of disaster victims: A simple and reliable method using CT of the paranasal sinuses

OBJECTIVE To assess the reliability of radiologic identification using visual comparison of ante and post mortem paranasal sinus computed tomography (CT). SUBJECTS AND METHODS The study was approved by the responsible justice department and university ethics committee. Four blinded readers with varying radiological experience separately compared 100 post mortem to 25 ante mortem head CTs with the goal to identify as many matching pairs as possible (out of 23 possible matches). Sensitivity, specificity, positive and negative predictive values were calculated for all readers. The chi-square test was applied to establish if there was significant difference in sensitivity between radiologists and non-radiologists. RESULTS For all readers, sensitivity was 83.7%, specificity was 100.0%, negative predictive value (NPV) was 95.4%, positive predictive value (PPV) was 100.0%, and accuracy was 96.3%. For radiologists, sensitivity was 97.8%, NPV was 99.4%, and accuracy was 99.5%. For non-radiologists, average sensitivity was 69.6%, negative predictive value (NPV) was 91.7%, and accuracy was 93.0%. Radiologists achieved a significantly higher sensitivity (p < 0.01) than non-radiologists. CONCLUSIONS Visual comparison of ante mortem and post mortem CT of the head is a robust and reliable method for identifying unknown decedents, particularly in regard to positive matches. The sensitivity and NPV of the method depend on the readers experience.

CT based volume measurement and estimation in cases of pericardial effusion

The measurement of fluid volumes in cases of pericardial effusion is a necessary procedure during autopsy. With the increased use of virtual autopsy methods in forensics, the need for a quick volume measurement method on computed tomography (CT) data arises, especially since methods such as CT angiography can potentially alter the fluid content in the pericardium. We retrospectively selected 15 cases with hemopericardium, which underwent post-mortem imaging and autopsy. Based on CT data, the pericardial blood volume was estimated using segmentation techniques and downsampling of CT datasets. Additionally, a variety of measures (distances, areas and 3D approximations of the effusion) were examined to find a quick and easy way of estimating the effusion volume. Segmentation of CT images as shown in the present study is a feasible method to measure the pericardial fluid amount accurately. Downsampling of a dataset significantly increases the speed of segmentation without losing too much accuracy. Some of the other methods examined might be used to quickly estimate the severity of the effusion volumes.

Sex determination from os sacrum by postmortem CT

Sex determination in forensic practice is performed mostly on sexually dimorphic bones, including pelvic bones such as the os sacrum. Postmortem CT scan provides an easy and fast method for depicting and measuring bone structures prior to elaborate autopsy preparations. To develop a simple and objective method for sex determination in postmortem CT, metric data were evaluated from CT images of the pelvic-associated os sacrum of 95 corpses (49 men and 46 women) from the Canton of Bern, Switzerland. Discriminant function analysis of the data showed that the best accuracy in determining sex was 76.8% and 78.9% with two different observers. It is concluded that measuring the os sacrumin postmortem CT for sex determination has moderate accuracy and should only be applied in combination with other methods.

Suicidal knife wound to the heart: Challenges in reconstructing wound channels with post mortem CT and CT-angiography

We present a case of an individual who stabbed himself through the heart with a large knife. Post mortem computed tomography (CT) and CT-angiography were used to assess the stab channel and to reconstruct the sequence of events. After penetrating injuries to the chest, both the intra-thoracic organs and the injury causing instrument may shift (e.g. from pnemothorax) and render forensic reconstructions more challenging. This case report illustrates the potentials and the pitfalls of CT for the reconstruction of penetrating injures to the chest.

Assessment of coronary artery disease by post-mortem cardiac MR

OBJECTIVES Minimally invasive or virtual autopsies are being advocated as alternative to traditional autopsy, but have limited abilities to detect coronary artery disease. It was the objective of this study to assess if the occurrence of chemical shift artifacts (CSA) along the coronary arteries on non-contrast, post-mortem cardiac MR may be used to investigate coronary artery disease. METHODS We retrospectively compared autopsy and CT findings of 30 cases with significant (≥75%), insignificant (<75%), or absent coronary artery stenosis to post-mortem cardiac MR findings. The chi-square test was used to investigate if the occurrence of CSA depends on the presence or absence of stenosis. Sensitivity, specificity and predictive values were calculated for each finding. RESULTS CSA indicates the absence of (significant) stenosis (p<0.001). The occurrence of paired dark bands in lieu of CSA on post-mortem cardiac MR suggests (significant) coronary arteries stenosis (p<0.001). Both findings have a high specificity but low sensitivity. CONCLUSIONS CSA is a marker of vessel patency. The presence of paired dark bands indicates stenosis. These criteria improve the ability of minimally invasive or virtual autopsy to detect coronary artery disease related deaths.

How reliable are Hounsfield-unit measurements in forensic radiology?

OBJECTIVE To assess the reliability of computed tomography (CT) numbers, also known as Hounsfield-units (HU) in the differentiation and identification of forensically relevant materials and to provide instructions to improve the reproducibility of HU measurements in daily forensic practice. MATERIALS AND METHODS We scanned a phantom containing non-organic materials (glass, rocks and metals) on three different CT scanners with standardized parameters. The t-test was used to assess the influence of the scanner, the size and shape of different types of regions-of-interest (ROI), the composition and shape of the object, and the reader performance on HU measurements. Intra-class correlation coefficient was used to assess intra- and inter-reader reliability. RESULTS HU values did not change significantly as a function of ROI-shape or -size (p>0.05). Intra-reader reliability reached ICC values >0.929 (p<0.001). Inter-reader reliability was also excellent with an ICC of 0.994 (p<0.001). Four of seven objects yielded significantly different CT numbers at different levels within the object (p<0.05). In 6/7 objects the HU changed significantly from CT scanner to CT scanner (p<0.05). CONCLUSION Reproducible CT number measurements can be achieved through correct ROI-placement and repeat measurements within the object of interest. However, HU may differ from CT-scanner to CT-scanner. In order to obtain comparable CT numbers we suggest that a dedicated Forensic Reference Phantom be developed.

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.