Postmortem Magnetic Resonance Imaging and Postmortem Computed Tomography in Ligature and Manual Strangulation

[Strangulation]

CLINICAL PROBLEM

Detection of manual strangulation, choking and hanging, as well as the intensity of these actions, helps to clarify the course of events, to enforce the state's right to prosecute and ultimately to protect against further attacks. However, this is complicated by the scarcity of externally visible findings.

STANDARD PROCEDURE TO DATE

The forensic examination of the head and neck after strangulation is carried out by means of external inspection to detect injuries and congestion above the strangulation level. Lesions below the surface of the skin, in particular of the subcutaneous fat tissue, the muscles or the laryngeal structures, usually escape the external inspection.

FORENSIC RADIOLOGY AS AN IMPORTANT COMPONENT

Imaging techniques allow internal injuries to be recorded and objectified, which can be of considerable added value in the collection of evidence. Since criminal proceedings must meet the highest standards of security, high demands are placed on imaging and diagnosis.

ASSESSMENT

Imaging techniques are suitable for detecting and objectifying internal injuries after a person has survived strangulation. However, their excellent reconstruction and visualization capabilities also make them a valuable addition to postmortem examinations.

RECOMMENDATIONS FOR PRACTICE

After reported and survived strangulation, choking or hanging, magnetic resonance imaging (MRI) of the soft tissues of the neck should be performed as soon as possible, and if cerebral damage is suspected, the skull should also be examined. If the event was not survived, whole-body computed tomography (CT) is now standard practice at many forensic medicine institutes.

Photon-counting CT for forensic death investigations-a glance into the future of virtual autopsy

This article explores the potential of photon-counting computed tomography (CT) in forensic medicine for a range of forensic applications. Photon-counting CT surpasses conventional CT in several key areas. It boasts superior spatial and contrast resolution, enhanced image quality at low x-ray energies, and spectral imaging capabilities that enable more precise material differentiation. These advantages translate to superior visualization of bone structures, foreign bodies, and soft tissues in postmortem examinations. The article discusses the technical principles of photon-counting CT detectors and highlights its potential applications in forensic imaging, including high-resolution virtual autopsies, pediatric forensic CT, trauma analysis, and bone density measurements. Furthermore, advancements in vascular imaging and soft tissue contrast promise to propel CT-based death investigations to an even more prominent role. The article concludes by emphasizing the immense potential of this new technology in forensic medicine and anthropology.

Diagnostic accuracy of post-mortem computed tomography for fractures of the hyoid-larynx complex

Post-mortem computed tomography (PMCT) is routinely used at many forensic institutions to guide the following autopsy and is especially useful for diagnosing fractures. This systematic review aims to investigate the sensitivity and specificity of a PMCT scan in fracture diagnosis of the hyoid-larynx complex (HLC) compared to traditional autopsy in cases involving traumatic neck injuries. We searched PubMed, SCOPUS and Web of Science and included papers with cases n ≥ 3 published between January 2000 and April 2023 reporting on PMCT and autopsy findings of fractures of the HLC. The search provided 259 results of which 10 were included. Overall sensitivity and specificity were 0.70 [0.59; 0.79] and 0.92 [0.80; 0.97] for hyoid bone fractures and 0.80 [0.62; 0.91] and 0.76 [0.63; 0.85] for the thyroid cartilage. The results show great variation, and a large range between studies. These results indicate that PMCT cannot replace autopsy in cases with HLC fractures. Future larger prospective studies are needed, examining fracture details, scan protocols and different slice thicknesses using uniform reporting.

Longitudinal visibility of MRI findings in living victims of strangulation

Initial experiences with magnetic resonance imaging (MRI) of living strangulation victims demonstrated additional findings of internal injuries compared to the standard clinical forensic examination. However, existing studies on the use of MRI for this purpose mostly focused on the first 48 h after the incident. The aims of this study were (a) to evaluate the longitudinal visibility of MRI findings after violence against the neck by performing two MRI examinations within 12 days and a minimum of four days between both MRI scans and (b) to assess which MRI sequences were most helpful for the detection of injuries. Twenty strangulation victims participated in this study and underwent one (n = 8) or two (n = 12) MRI scans. The first MRI examination was conducted during the first five days, the second five to 12 days after the incident. Two blinded radiologists assessed the MRI data and looked for lesions in the structures of the neck. In total, 140 findings were reported in the 32 MRI examinations. Most of the findings were detected in the thyroid and the muscles of the neck. T2-weighted SPACE with fat suppression, T1-weighted TSE and T1-weighted MPRAGE were rated as the most helpful MRI sequences. Subjects who showed findings in the initial scan also demonstrated comparable results in the second scan, which was performed on average 8.4 days after the incident. Our results show that even up to 12 days after the incident, the criminal proceeding of strangulation cases may greatly profit from the information provided by an MRI examination of the neck in addition to the standard clinical forensic examination.

Comparison of findings identified at traditional invasive autopsy and postmortem computed tomography in suicidal hangings

Cases of suicidal hanging are a common death referred for medico-legal autopsy throughout the world. Although some advocate using postmortem computed tomography (PMCT) without traditional invasive autopsy (TIA) to investigate such deaths, others reject this approach. There is currently limited evidence to guide practice. In this context, the TIA reports and PMCT images of 50 cases of suspected suicidal hanging during an 11-month period were reviewed. The reviewers were blinded to the findings of the other modality. A Cohen’s Kappa coefficient (K) was calculated to assess agreement between TIA and PMCT across a range of pertinent findings. This analysis demonstrated perfect agreement for identification of a ligature (K = 1.00) and a strong level of agreement for identification of a ligature suspension point (K = 0.832) but only a minimal level of agreement for overall ligature mark (K = 0.223). PMCT demonstrated a weak level of agreement for fractures of hyoid bone (K = 0.555) and thyroid cartilage (K = 0.538). Three probable fractures not identified at TIA were identified on PMCT. TIA was shown to be superior in the identification of intramuscular and laryngeal fracture–related haemorrhage/bruising whereas PMCT was superior to TIA in identifying body gas deposition. There was overall good correlation between the natural disease and trauma identified elsewhere in the body during the TIA and PMCT. The study demonstrates that PMCT can assist the investigation of suspected suicidal hangings. However, the accuracy of many findings is limited, and if it is used as an alternative to the TIA, potentially pertinent findings, such as fractures of the laryngeal cartilages, could be missed.