Multiphase Postmortem Computed Tomography Angiography in Pediatrics: A Case Report

Pediatric forensic postmortem computed tomography: basics to advanced

The approach to postmortem computed tomography (CT) differs significantly from that of diagnostic CT in living patients. Elimination of artifacts such as noise and beam hardening as well as optimization of tissue contrast requires alteration of exposure parameters from protocols designed to limit radiation dose in children. Multiple scans may be performed, and detailed post-processing can be used to enhance subtle findings such as small intracranial extra axial collections and non-displaced fractures. Basics of postmortem CT technique are discussed here as well as advanced techniques in scanning and post-processing.

Pediatric postmortem CT angiography: validation of vascular access for PMCT angiography in stillbirths, babies and toddlers

PURPOSE

The use of angiography in postmortem CT angiography (PMCTA) has several advantages. In adults, femoral vascular access is well established. Due to the small and specific anatomy in fetuses and infants, the technique has to be adapted, especially regarding the vascular access. The aim of this study was to evaluate vascular access for pediatric PMCTA (pedPMCTA).

MATERIALS AND METHODS

Ten pedPMCTAs were performed in stillbirths, babies, and one toddler. A femoral approach by cannulation of the femoral artery and vein, an umbilical approach by cannulation of the umbilical vessels, and an intraosseous approach by an intraosseous needle were evaluated by handling and resulting imaging.

RESULTS

The insertion of a cannula with a size of 18-20 G in the femoral vessels was possible in babies. An umbilical access with peripheral venous cannulas with a size of 14-20 G was feasible in stillbirths and newborns. An intraosseous access is advisable as equal alternative to umbilical and in cases where a femoral access is not possible. The most significant problem with the vascular access is the extravasation of contrast media, but this can be reduced significantly with practice.

CONCLUSION

When performing pedPMCTA, an umbilical vascular access is recommended if an umbilical cord with open vessels is still present. Otherwise, a bone marrow access should be preferred in the presence of an arteriovenous shunt or if only the venous system needs to be shown. If that is not the case, the femoral access with the possibility to separate venous and arterial scan should be used.

Forensic post-mortem CT in children

Post-mortem computed tomography (PMCT) imaging is gaining popularity and acceptance for use alongside forensic autopsies of children, predominantly to aid in the detection of traumatic injuries. Recent research on this topic has provided a breadth of new information regarding the appropriate usage, imaging guidance, and diagnostic accuracy for the identification of different paediatric pathologies. Additionally, advanced CT imaging techniques, such as PMCT angiography or ventilated PMCT, have been trialled, and post-mortem micro-CT is now being used in specialist centres for the assessment of subtle fractures in extracted bone specimens. Various image post-processing methods (e.g., three-dimensional printing from PMCT imaging data) are being used for the illustration of injuries in the medicolegal setting to a lay audience and provide another avenue for the future of forensic radiology research. In this review, the evidence-based principles and benefits of post-mortem imaging for forensic investigation in childhood deaths are presented, with a particular focus on PMCT and current practices. Variations in forensic imaging strategies around the world, published diagnostic accuracy rates, and expected normal post-mortem imaging findings are discussed, as well as potential future applications and research in this area.

[Bridging vein injuries in shaken baby syndrome : Forensic-radiological meta-analysis with special focus on the tadpole sign]

Shaken baby syndrome is a common variant of the abusive head trauma in infants and toddlers and is still subject of intensive research. In recent years, a number of radiological studies on the diagnostic and forensic relevance of injured bridging veins were conducted using different imaging modalities. The present article will give an overview on the current state of research in this field and will discuss the forensic implications. The meta-analysis of the seven currently existing studies revealed that injuries of the bridging veins and bridging vein thromboses, respectively, frequently appear as rounded, enlarged, and/or tubular structures. The "tadpole sign" may serve as a valuable tool for the identification of these formations. Especially, T2*/SWI (susceptibility-weighted imaging) sequences allow for good detectability of these lesions and should always be generated when abusive head trauma is suspected. In conclusion, it can be recommended that the presence of radiologically detectable bridging vein injuries should give reason to search for other manifestations of physical child abuse.

Towards multi-phase postmortem CT angiography in children: a study on a porcine model

PURPOSE

Multi-phase postmortem computed tomography angiography (MPMCTA) is a growing technique, which is standardized for adults. Application of this protocol for a children population is not so well defined. Our study aims to adapt the adult's protocol to children, using a porcine model.

MATERIAL AND METHODS

Three groups of 18 pigs were studied, with a weight distribution between 4 and 48 kg. Different pump devices were used. Pigs of group I were studied using the Virtangio® machine, whereas pigs of groups II and III were studied using used the Medrad® machine. Study of vascular opacification was possible using a semi-quantitative method based on 26 arterial and 26 venous segments that were distributed over the entire body from the cephalic extremity to the posterior pawns.

RESULTS

While thoracic, abdominal, and pelvic vascular opacification were complete for each individual pig in a group, group III showed better vascular opacification for the cephalic extremity. This was also true for anterior and posterior pawns vascular opacification. Spearman correlation tests showed a significant relationship between anthropometric characteristics of pigs, injection parameters, and percentage of opacified segments. A higher percentage of opacification was obtained for individuals of lower weights, with comparatively lower quantities of contrast agent injected.

CONCLUSION

Postmortem computed tomography angiography (PMCTA) was possible for all the individuals, particularly for small weights (4 kg) using the Medrad® machine. However, further studies are needed to better understand the procedure.

Modern post-mortem imaging: an update on recent developments

Modern post-mortem investigations use an increasing number of digital imaging methods, which can be collected under the term "post-mortem imaging". Most methods of forensic imaging are from the radiology field and are therefore techniques that show the interior of the body with technologies such as X-ray or magnetic resonance imaging. To digitally image the surface of the body, other techniques are regularly applied, e.g. three-dimensional (3D) surface scanning (3DSS) or photogrammetry. Today's most frequently used techniques include post-mortem computed tomography (PMCT), post-mortem magnetic resonance imaging (PMMR), post-mortem computed tomographic angiography (PMCTA) and 3DSS or photogrammetry. Each of these methods has specific advantages and limitations. Therefore, the indications for using each method are different. While PMCT gives a rapid overview of the interior of the body and depicts the skeletal system and radiopaque foreign bodies, PMMR allows investigation of soft tissues and parenchymal organs. PMCTA is the method of choice for viewing the vascular system and detecting sources of bleeding. However, none of those radiological methods allow a detailed digital view of the body's surface, which makes 3DSS the best choice for such a purpose. If 3D surface scanners are not available, photogrammetry is an alternative. This review article gives an overview of different imaging techniques and explains their applications, advantages and limitations. We hope it will improve understanding of the methods.

Whole-body post-mortem computed tomography angiography of a newborn revealing transposition of great arteries

The number of medico-legal post-mortem examinations referring to newborns is considerably low: In the case of the Chair and Department of Forensic Medicine of the author's origin, the autopsy rate of such cases is less than 1%. Even experienced forensic pathologists can find the technical autopsy procedure of a newborn quite difficult. Post-mortem imaging using unenhanced post-mortem computed tomography (PMCT) gives only a limited opportunity to help in conventional autopsy examination. By adding contrast medium (CA) administration, we can significantly expand diagnostic capabilities. However, the post-mortem computed tomography angiography (PMCTA) technique has already been developed mostly in adult death cases (as considerably much more frequent), and no standardised protocol for examination of children exists. The authors present the dual-phase PMCTA examination of a newborn by manual CA administration using the access to umbilical vessels (vein and artery) unveiling transposition of the great arteries (TGA). The results are presented as multiplanar reformatted (MPR) images and three-dimensional (3D) images by volume/surface-rendered reconstructions, giving a contribution towards proving the value of forensic imaging in post-mortem examinations of heart and vascular malformations in newborns.