Optical coherence tomography

A review is presented of different scanning, acquisition and processing techniques used to obtain depth-resolved information in optical-coherence tomography (OCT). The principles and performances of different OCT techniques are discussed and images from different types of tissue are presented. Special attention is devoted to the progress in using the time-domain flying spot OCT technique and combination of the en face OCT imaging with confocal microscopy. Although OCT is based on white light interferometry, which is a well established and an old technology, the quest for higher resolution and faster acquisition of in vivo images has ensured OCT a rapid evolution in the last decade. Highly adventurous avenues to expand the OCT capabilities and trends are presented at the end of the review.     

The reconstruction: a useful tool in forensic sciences

The intervention of a forensic pathologist may be required at any stage of a judicial investigation. Clearly, he or she plays an important role at a crime scene and later on during the examination of the body. But the forensic pathologist's contribution is equally important during reconstruction, which is most frequently called for in cases of violent deaths, homicides in particular. However, reconstruction may also be very useful in cases of less importance in terms of criminal law. It requires little investment and can provide precious evidence. In the two cases presented here we were able to exclude, respectively, the presumption of the adulteration of a blood sample taken for alcohol dosage and the accidental origin of an attempted murder. In fact, reconstruction may be a valuable procedure in any event requiring the participation of a forensic expert.     

Inca bone in forensic autopsy: a report of two cases with a review of the literature

Complete tripartite and complete asymmetric bipartite bones were, respectively, found in the interparietal region of the occipital bone in two forensic autopsy cases that we encountered. These isolated bones are called the Inca bones, or interparietal bones, which occasionally occur as a result of incomplete fusion of the ossifying nuclei during the developmental course. The Inca bones were detectable on ante-mortem cranial radiographs in these two cases. We review the embryological background of this variation, discuss the significance of this variation in forensic medicine, and additionally, present a review of the frequencies of other non-metrical characteristics of the skulls that may be detectable at the time of autopsy.     

Advanced computed tomography technology and patient dose: a literature review

Cumulative patient radiation dose is a hot topic making headlines today. Responsible for almost two thirds of the medical radiation dose given to patients, computed tomography (CT) has been the major target of these news articles. Through this review of peer reviewed publications, an examination of the relationship between the advancement of technology in CT equipment and the increasing patient dose areexplored. Discussion includes CT scan protocols, demands of physicians, equipment capabilities, and possible solutions to address the problem. Although most of these issues are well known in the imaging community, a few of the results are somewhat surprising. The information disclosed will help form a path to a future with lowerradiation doses received by all patients.     

Optical coherence tomography in the assessment of oral squamous cell carcinoma resection margins

BackgroundIncomplete surgical removal of cancer is believed to be the main cause of local recurrence and high mortality. This study assessed the use of optical technology (namely optical coherence tomography [OCT]) in examining oral squamous cell carcinoma (OSCC) resection margins to assess if this modality could guide the surgeon during surgical resections.Materials and methodsTwenty-eight T₁–T₂ N0M0 oral squamous cell carcinoma patients participated in this study. Nineteen patients were males and nine were females. The majority of lesions were in the ventro-lateral tongue, floor of mouth, retromolar trigone and the buccal mucosa.Following tumour resection, the specimen resection margins were optically scanned in the immediate ex vivo phase. Two independent assessors commented on the four resection margins of each specimen. The findings were then compared to the corresponding gold standard histopathology. The average epithelial thickness for both tumor-free and tumor-involved margins was also calculated.ResultsThe pathology reports of the 112 margins revealed 90 tumor-free margins and 22 tumor-involved margins. Examining the data from both senior operating surgeons (assessors), the overall sensitivity and specificity was found to be 81.5% and 87%, respectively. Whilst the positive predictive value was 61.5% and the negative predictive value was 95%. OCT accuracy for the first assessor was 88% and for the second assessor 84%. The assessors’ inter-observer agreement was “very good” for superior, inferior and medial margins; while agreement on the lateral surgical margin status was “good”. Using OCT, the mean epithelial thickness at the tumor-free resection margins was 360 μm; while, it was 567 μm for the tumour-involved margins.ConclusionOCT is a valuable tool in the assessment of surgical margins. Tumour-involved margins can be identified by architectural changes and increase in epithelial layer thickness on the OCT image. Further studies are required to assess tumour margins in vivo.     

Carbofuran self-poisoning: forensic and analytic investigations in twins and literature review

International Journal of Legal Medicine - Carbofuran is a pesticide widely used in agricultural context to kill insects, mites, and flies by ingestion or contact. Along with literature review, we...     

Bayesian networks for evaluating forensic DNA profiling evidence: a review and guide to literature

Almost 30 years ago, Bayesian networks (BNs) were developed in the field of artificial intelligence as a framework that should assist researchers and practitioners in applying the theory of probability to inference problems of more substantive size and, thus, to more realistic and practical problems. Since the late 1980s, Bayesian networks have also attracted researchers in forensic science and this tendency has considerably intensified throughout the last decade. This review article provides an overview of the scientific literature that describes research on Bayesian networks as a tool that can be used to study, develop and implement probabilistic procedures for evaluating the probative value of particular items of scientific evidence in forensic science. Primary attention is drawn here to evaluative issues that pertain to forensic DNA profiling evidence because this is one of the main categories of evidence whose assessment has been studied through Bayesian networks. The scope of topics is large and includes almost any aspect that relates to forensic DNA profiling. Typical examples are inference of source (or, 'criminal identification'), relatedness testing, database searching and special trace evidence evaluation (such as mixed DNA stains or stains with low quantities of DNA). The perspective of the review presented here is not exclusively restricted to DNA evidence, but also includes relevant references and discussion on both, the concept of Bayesian networks as well as its general usage in legal sciences as one among several different graphical approaches to evidence evaluation.     

Gender equity: how do the forensic sciences fare?

ABSTRACT

Females are underrepresented in science, technology, engineering and mathematics (STEM) at all levels of society. Fewer females are completing STEM school subjects, graduating with STEM degrees, being employed as STEM professionals, and holding senior leadership and academic positions in STEM. However, unlike almost every other STEM discipline, the overall ratio of females is higher in many forensic science disciplines. For our sector, rather than having difficulty in attracting females, the bigger issue is how we retain and promote female talent. This complex issue is exacerbated by: gender pay gaps; family role expectations; lack of visible role models or mentors; discrimination and harassment; and bias during recruitment and promotion practices. We discuss barriers relevant for women in the forensic industry and offer potential solutions. These include flexible work arrangements, sponsorship programmes, and fostering and practising an inclusive workplace culture. Gender equity programmes and exemplar STEM organizations focused on a commitment to gender parity will be explored. Harnessing untapped female talent is as much a social justice issue as employing best practices for improving the quality, diversity and output of our forensic science workforce, and research and innovation strategies.     

Non-cryogenic forensic tissue preservation in the field: a review

There are many non-cryogenic tissue preservatives that have been employed for human and non-human specimens and in this review we examine their potential for use in field-based forensic operations such as disaster victim identification (DVI). A number of preservatives show promise for short tandem repeat (STR) profiling of human tissue including FTA paper, solid salt, DMSO, ethanol, buffers and proprietary preservatives. Their use will be governed by considerations such as user safety, cost, ease of use and transport.     

Diagnosable and non-diagnosable causes of death by postmortem computed tomography: a review of 339 forensic cases

Postmortem computed tomography (PMCT) is often used to diagnose causes of death, especially in nations with a low autopsy rate. To identify the causes of death that can and cannot be determined by PMCT, imaging findings were reviewed in 339 consecutive forensic autopsy cases. Causes of death could be determined based on PMCT findings alone in 7% of these cases, based on suggestive PMCT findings with additional information in 54%, and could not be determined by PMCT in 38%. PMCT screening may be useful for establishment of some causes of death, including traumatic intracranial hematoma, endogenous intracranial hemorrhage, and some cases of cardiac rupture. Suggestive findings from PMCT in other cases, such as those involving subarachnoid hemorrhage or pericardial hematoma, can lead to misdiagnosis and may be a pitfall of PMCT screening. Causes of death including some cases of cervical cord injuries, asphyxiation, burn, drug intoxication, acute myocardial infarction, and pulmonary thromboembolism cannot be diagnosed using PMCT.     

Mushroom toxins: a forensic toxicological review

Mushrooms are ubiquitous in the world. Amateur hunters harvest mushrooms growing in forests to enjoy eating them as seasonal delicacies, and occasionally they cause poisonings and even deaths. In this review, mushroom toxins are tabulated according to mushroom species, symptoms, toxicities and analytical methods on the basis of references. Second, because we constructed a method for analysis of amatoxins, the most virulent mushroom toxins, by liquid chromatography-time-of-flight-mass spectrometry, we introduce it for use in forensic toxicology. Third, an extensive poisoning incident after consumption of the usually edible mushroom Pleurocybella porrigens took place in nine prefectures in Japan from September to December 2004, resulting in 59 poisoned people including 19 deaths; this incident is briefly described and discussed in relation to its causative toxin(s). Finally, we present the chemical structures of new toxins purified from the highly toxic mushrooms Podostroma cornu-damae and Russula subnigricans; their structures were very unique, and the toxicities were comparable to those of amatoxins. From the forensic toxicological point of view, reports on sophisticated methodology for analyses of mushroom toxins seem to be too scant even for the well-known toxins. Hereafter, a number of toxic mushrooms and their new toxins are expected to be disclosed, especially because of environmental changes such as the global warming phenomenon.     

Clinical applications of anterior segment swept-source optical coherence tomography: A systematic review

Optical coherence tomography (OCT) is a non-invasive method that provides the opportunity to examine tissues by taking cross-sectional images. OCT is increasingly being used to evaluate anterior segment (AS) pathologies. Swept-source (SS) OCT allows greater penetration and achieves better visualization of the internal configuration of AS tissues due to the longer wavelength employed and high scan speeds. We reviewed the utilization of AS SS-OCT in various conditions including glaucoma, ocular surface pathologies, iris tumors, refractive surgery, cataract surgery, and scleral diseases. A systematic literature search was carried out on PubMed, Scopus, and Web of Science databases between January 1, 2008, and September 1, 2022 using the following keywords: AS SS-OCT; dry eye and SS-OCT; ocular surface and SS-OCT; cornea and SS-OCT; dystrophy and SS-OCT; glaucoma and SS-OCT; ocular surface tumors and SS-OCT; conjunctival tumors and SS-OCT; refractive surgery and SS-OCT; cataract and SS-OCT; biometry and SS-OCT; sclera and SS-OCT; iris and SS-OCT; ciliary body and SS-OCT; artificial intelligence and SS-OCT. A total of 221 studies were included in this review. Review of the existing literature shows that SS-OCT offers several advantages in the diagnosis of AS diseases. Exclusive features of SS-OCT including rapid scanning, deeper tissue penetration, and better image quality help improve our understanding of various AS pathologies.     

Optical coherence tomography angiography findings in transfusion-dependent beta-thalassemia patients with and without splenectomy

BackgroundOcular involvement is common in transfusion-dependent beta-thalassemia (TDβ-T) patients. We aimed to investigate the effect of splenectomy on optical coherence tomography angiography (OCTA) findings in TDβ-T patients.MethodsThe study is a prospective cross-sectional study. A total of 45 eyes of 23 patients with splenectomy (34.04±8.83 years), 18 eyes of 9 patients without splenectomy (27.44±5.43 years), and 54 eyes of 27 controls (33.22±6.44 years) were included. Vessel density in superficial capillary plexus, deep capillary plexus and radial peripapillary capillary, foveal avascular zone, choriocapillaris flow area, choroidal and retinal thickness detected by OCTA were evaluated. p < 0.05 was considered significant.ResultsVessel density of superficial capillary plexus and deep capillary plexus were similar in patients with and without splenectomy, and controls. Choriocapillaris flow area was significantly decreased in patients with splenectomy than that in those without splenectomy and controls (2.02±0.12 vs. 2.17±0.1 and 2.14±0.12; p < 0.001). Choroidal thickness was significantly lower in patients without splenectomy than in patients with splenectomy and controls (260.05±61.02 vs. 305.11±42.13 and 298.89±29.14, p = 0.008). Parafoveal and perifoveal thickness of the full retina and outer retina were significantly lower in patients without splenectomy than in patients with splenectomy and controls (301.06±10.0, 279.78±10.28 vs. 311.04±14.89, 290.87±13.67 and 316.63±13.57, 289.56±9.31, p < 0.001 and p = 0.002; 174.72±7.81, 167.17±6.21 vs. 182.87±8.81, 173.60±7.09 and 185.11±9.26, 173.96±6.79, p = 0.001 and p < 0.001, respectively).ConclusionsOCTA findings can provide information about the microvascular effects of splenectomy on the retina of patients with TDβ-T.     

Alternative matrices in forensic toxicology: a critical review

Forensic Toxicology - The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in...     

Virtual autopsy using imaging: bridging radiologic and forensic sciences. A review of the Virtopsy and similar projects

The transdisciplinary research project Virtopsy is dedicated to implementing modern imaging techniques into forensic medicine and pathology in order to augment current examination techniques or even to offer alternative methods. Our project relies on three pillars: three-dimensional (3D) surface scanning for the documentation of body surfaces, and both multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) to visualise the internal body. Three-dimensional surface scanning has delivered remarkable results in the past in the 3D documentation of patterned injuries and of objects of forensic interest as well as whole crime scenes. Imaging of the interior of corpses is performed using MSCT and/or MRI. MRI, in addition, is also well suited to the examination of surviving victims of assault, especially choking, and helps visualise internal injuries not seen at external examination of the victim. Apart from the accuracy and three-dimensionality that conventional documentations lack, these techniques allow for the re-examination of the corpse and the crime scene even decades later, after burial of the corpse and liberation of the crime scene. We believe that this virtual, non-invasive or minimally invasive approach will improve forensic medicine in the near future.     

Laser capture microdissection in forensic research: a review

In forensic sciences, short tandem repeat (STR) analysis has become the prime tool for DNA-based identification of the donor(s) of biological stains and/or traces. Many traces, however, contain cells and, hence, DNA, from more than a single individual, giving rise to mixed genotypes and the subsequent difficulties in interpreting the results. An even more challenging situation occurs when cells of a victim are much more abundant than the cells of the perpetrator. Therefore, the forensic community seeks to improve cell-separation methods in order to generate single-donor cell populations from a mixed trace in order to facilitate DNA typing and identification. Laser capture microdissection (LCM) offers a valuable tool for precise separation of specific cells. This review summarises all possible forensic applications of LCM, gives an overview of the staining and detection options, including automated detection and retrieval of cells of interest, and reviews the DNA extraction protocols compatible with LCM of cells from forensic samples.     

Considerations when designing human performance tests in the forensic sciences

In their 2009 report ‘Strengthening Forensic Science in the United States: A Path Forward’ the National Academies of Science (NAS) called for the development of a body of research establishing the limits of the performance of forensic scientists on a range comparison tasks. The NAS proposed that this could be facilitated through collaboration between the forensic sciences and broader research communities. In this paper we outline a range of issues cognitive scientists routinely consider when designing human performance tests. In doing so the aim is to provide forensic scientists with tools to help avoid common research design errors while also laying a common foundation for further collaborations between cognitive and forensic scientists as sought by the NAS.