Biomedical subjects

M J Thali

Publications and source records attributed to M J Thali.

13 recordsLinked to original sources

PubMed2005

Maximum intensity projection of cranial computed tomography data for dental identification.

Dental radiographs play the major role in the identification of victims in mass casualties besides DNA. Under circumstances such as those caused by the recent tsunami in Asia, it is nearly impossible to document the entire dentition using conventional x-rays as it would be too time consuming. Multislice computed tomography can be used to scan the dentition of a deceased within minutes, and the postprocessing software allows visualization of the data adapted to every possible antemortem x-ray for identification. We introduce the maximum intensity projection of cranial computed tomography data for the purpose of dental identification exemplarily in a case of a burned corpse. As transportable CT scanners already exist, these could be used to support the disaster victim identification teams in the field.

Burns↗

PubMed2004

Is 'virtual histology' the next step after the 'virtual autopsy'? Magnetic resonance microscopy in forensic medicine.

AIM: The study aimed to validate magnetic resonance microscopy (MRM) studies of forensic tissue specimens (skin samples with electric injury patterns) against the results from routine histology. METHODS AND RESULTS: Computed tomography and magnetic resonance imaging are fast becoming important tools in clinical and forensic pathology. This study is the first forensic application of MRM to the analysis of electric injury patterns in human skin. Three-dimensional high-resolution MRM images of fixed skin specimens provided a complete 3D view of the damaged tissues at the site of an electric injury as well as in neighboring tissues, consistent with histologic findings. The image intensity of the dermal layer in T2-weighted MRM images was reduced in the central zone due to carbonization or coagulation necrosis and increased in the intermediate zone because of dermal edema. A subjacent blood vessel with an intravascular occlusion supports the hypothesis that current traveled through the vascular system before arcing to ground. CONCLUSION: High-resolution imaging offers a noninvasive alternative to conventional histology in forensic wound analysis and can be used to perform 3D virtual histology.

Adult↗

PubMed2003

The evaluation of a synthetic long bone structure as a substitute for human tissue in gunshot experiments.

Our goal was to compare experimental gunshot wounds in our non-biological bone model with similarly created wounds in swine bones, and evaluate the results. The design of the synthetic (polyurethane) bone was patterned after human bone structure, with a compact outer layer covering a porous inner layer. Ordnance gelatin, as substitute bone marrow, was injected into the bone's hollow core. To simulate the periostium, the bone was covered with a layer of latex. Then the bone was embedded in gelatin used to simulate surrounding soft tissue. For comparison, fresh swine bones were also embedded in gelatin, and fired upon under the same guidelines. All gunshots were high-speed filmed. In our experimental study, gunshot wounds to swine bones, and to our synthetic, non-biological bones were compared. The results (the comparison between the biological swine bones and the non-biological model bones) in regard to the following points are absolutely equal: the loss of velocity and energy after striking bone, bone fragmentation, bullet deformation, and the penetrating wound channel. Continuing studies with our synthetic bone model will bring about an even greater understanding of the mechanisms of "bullet-bone interaction". For this reason, we have extended our variety of bone models to include other skeletal structures such as skull, spine, pelvis and flat bones for further gunshot experiments.

Animals↗

PubMed2003

Bite mark documentation and analysis: the forensic 3D/CAD supported photogrammetry approach.

Bite mark identification is based on the individuality of a dentition, which is used to match a bite mark to a suspected perpetrator. This matching is based on a tooth-by-tooth and arch-to-arch comparison utilising parameters of size, shape and alignment. The most common method used to analyse bite mark are carried out in 2D space. That means that the 3D information is preserved only two dimensionally with distortions. This paper presents a new 3D documentation, analysis and visualisation approach based on forensic 3D/CAD supported photogrammetry (FPHG) and the use of a 3D surface scanner. Our photogrammetric approach and the used visualisation method is, to the best to our knowledge, the first 3D approach for bite mark analysis in an actual case. The documentation has no distortion artifacts as can be found with standard photography. All the data are documented with a metric 3D measurement, orientation and subsequent analysis in 3D space. Beside the metrical analysis between bite mark and cast, it is possible using our method to utilise the topographical 3D feature of each individual tooth. This means that the 3D features of the biting surfaces and edges of each teeth are respected which is--as shown in our case--very important especially in the front teeth which have the first contact to the skin. Based upon the 3D detailed representation of the cast with the 3D topographic characteristics of the teeth, the interaction with the 3D documented skin can be visualised and analysed on the computer screen.

Bites, Human↗

PubMed2003

Into the decomposed body-forensic digital autopsy using multislice-computed tomography.

It is impossible to obtain a representative anatomical documentation of an entire body using classical X-ray methods, they subsume three-dimensional bodies into a two-dimensional level. We used the novel multislice-computed tomography (MSCT) technique in order to evaluate a case of homicide with putrefaction of the corpse before performing a classical forensic autopsy. This non-invasive method showed gaseous distension of the decomposing organs and tissues in detail as well as a complex fracture of the calvarium. MSCT also proved useful in screening for foreign matter in decomposing bodies, and full-body scanning took only a few minutes. In conclusion, we believe postmortem MSCT imaging is an excellent vizualisation tool with great potential for forensic documentation and evaluation of decomposed bodies.

Autopsy↗

PubMed2003

Analysis of patterned injuries and injury-causing instruments with forensic 3D/CAD supported photogrammetry (FPHG): an instruction manual for the documentation process.

Forensic 3D/CAD supported photogrammetry (FPHG) is a method of recording and documenting the surface of small objects, thus enabling a three-dimensional image of these objects in virtual space. With this representation on the computer screen the course of forensically relevant events can be reconstructed. The procedure allows for examining patterned injuries of skin, soft tissue or bones for matching potentially incriminated instruments in shape, size and angle.3D recording of objects to be examined requires taking series of photographs. A computer system then calculates the position in space of certain points on the surface of the objects and subsequently produces 3D data models of the objects. Using a 3D/CAD program these data models are used to generate graphic true-to-object volume models. The objects in question can then be moved against each other arbitrarily on the screen-depending on the questions to be answered-in order to compare them and possibly establish their congruence. This article covers the state of the art in FPHG procedures in the form of a step-by-step instruction. It also illustrates the wide range of FPHG applications.

Forensic Medicine↗

PubMed2003

A high-speed study of the dynamic bullet-body interactions produced by grazing gunshots with full metal jacketed and lead projectiles.

Experimenting upon a synthetic, non-biological Skull-Brain Model, our goal was to document and study the bullet-body interaction of grazing (glancing, tangential) gunshots. Thanks to the high-speed study of the dynamic bullet-body interaction it was possible to document the glancing behavior of projectiles with a resolution of 50 million pictures per second. It was possible to demonstrate the differing deformation and fragmentation patterns between the 9mm Luger full metal jacketed projectile and the 38 Smith & Wesson (S & W) lead round nose projectile. In a true-to-life manner the morphologic fracture systems could be documented by utilization of the model in dependence of the projectile's behavior, deformation, and fragmentation. Based on these experimental studies with body models, conclusions could be drawn for surgical and reconstructive forensic questions in real cases. In summary, model substitutes offer a suitable basis for the study of the bullet-body interaction because the experiments are reproducible, totally independent of the biological variances of corpse and animal experiments, and are harmless from the ethical perspective.

Brain Injuries↗

PubMed2002

The dynamic development of the muzzle imprint by contact gunshot: high-speed documentation utilizing the "skin-skull-brain model".

Many contact gunshots produce a muzzle imprint in the skin of the victim. Different mechanisms have been discussed in literature as being responsible for the creation of the muzzle imprint. Experimenting upon the synthetic non biological skin-skull-brain model, our goal was to document and study the creation of the muzzle imprint with the aid of high-speed photography. In our experiments, we could document with our high-speed photography (at exposure rates in the range of nanoseconds) the bulging, the pressing against the muzzle, and the splitting of the artificial skin. Furthermore, it was possible to photographically record the back pattern of synthetic tissue particles. And, the soot and gunpowder cavity could be reproduced experimentally. In conclusion the experiments completed with the skin-skull-brain model, using high-speed photography for documentation, show the promising possibilities of experimental ballistics with body models.

Brain Injuries↗

PubMed2002

The "skin-skull-brain model": a new instrument for the study of gunshot effects.

In order to create and study wound morphology, a "skin-skull-brain model" had to be designed which would make the laboratory reproduction of a real ballistic injury possible. To simulate the human skin, an artificial skin (a silicon cap) is used. This silicon scalp contains synthetic fibers (artificial leather) to simulate the collagen and fat of the scalp. The artificial skull is a layered polyurethane sphere (19 cm o.d.; and 5, 6, or 7 mm thick) constructed in a specially designed form with a Tabula externa, Tabula interna, and a porous Diploe sandwiched in between. The periostium of the artificial skull is made of latex. This elastic latex layer prevents the bone fragments from scattering after the model has been struck by gunfire. The brain itself is simulated with ordnance gelatin, 10% at 4 degrees C, a material well known in wound ballistics. Gunshots were fired at a distance of 10 m from the model. During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot injuries. Using the "skin-skull-brain model" has some significant advantages: the model is inexpensive, easy to construct, instantly available for use, and eliminates ethics conflicts. The main advantage of such a model is, in comparison with biological substances, the high reproducibility of inflicted traumas.

Brain Injuries↗

PubMed2002

A study of the morphology of gunshot entrance wounds, in connection with their dynamic creation, utilizing the "skin-skull-brain model".

The goal of this study was to document the dynamic effects created within, and the developing mechanisms of a gunshot entrance wound to the skin utilizing high-speed photography and the "skin-skull-brain model". The high-speed photography was taken with an Imacon 468/Hadland-Photonics camera. Full metal jacketed, 9 mm Luger projectiles were fired at the target model from a distance of 10 m. During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot entrance wounds. It has been possible to document and study the dynamic process of the "bullet-skin-interaction" in the gunshot entrance wound. The development of the morphologic terms of the entrance wound are discussed. In combination with high-speed photography, this "skin-skull-brain model" is a perfect tool for the documentation and the study of the dynamic development of gunshot entrance wounds in the skin.

Brain Injuries↗

PubMed2001

Body models in forensic ballistics: reconstruction of a gunshot injury to the chest by bullet fragmentation after shooting through a finger.

Forensic science uses substitutes to reconstruct injury patterns in order to answer questions regarding the dynamic formation of unusual injuries. Using a case study, an experimental simulation of a finger was designed, for the first time with a combination of hard wood and glycerin soap. With this model as an intermediate target simulation, it was possible not only to demonstrate the "bullet-body (finger) interaction", but also to recreate the wound pattern found in the victim. This case demonstrates that by using ballistic models and body-part substitutes, gunshot cases can be reproduced simply and economically, without coming into conflict with ethical guidelines.

Finger Injuries↗

PubMed2000

Matching tire tracks on the head using forensic photogrammetry.

In the field of the documentation of forensics-relevant injuries, from the reconstructive point of view, the forensic, CAD-supported photogrammetry plays an important role; particularly so when a detailed 3-D reconstruction is vital. This is demonstrated with a soft-tissue injury to the face caused by being run over by a car tire. Since the objects (injury and surface of the tire) to be investigated will be evaluated in virtual space, they must be series photographed. These photo sequences are then evaluated with the RolleiMetric multi-image evaluation system. This system measures and calculates the spatial location of points shown in the photo sequences, and creates 3-D data models of the objects. In a 3-D CAD program, the model of the injury is then compared against the model of the possible injury-causing instrument. The validation of the forensic, CAD-supported photogrammetry, as shown by the perfect 3-D match between the tire tread and the facial injury, demonstrates how greatly this 3-D method surpasses the classic 2-D overlay method (one-to-one photography).

Accidents, Traffic↗

PubMedDate not supplied

Extended CT scale overcomes restoration caused streak artifacts for dental identification in CT--3D color encoded automatic discrimination of dental restorations.

OBJECTIVE: Besides DNA, dental radiographs play a major role in the identification of victims in mass casualties or in corpses with major postmortem alterations. Computed tomography (CT) is increasingly applied in forensic investigations and is used to scan the dentition of deceased persons within minutes. We investigated different restoration materials concerning their radiopacity in CT for dental identification purposes. METHODS: Extracted teeth with different filling materials (composite, amalgam, ceramic, temporary fillings) were CT scanned. Radiopacities of the filling materials were analyzed in extended CT scale images. RESULTS: Radiopacity values ranged from 6000-8500HU (temporary fillings), 4500-17000HU (composite fillings) and >30710HU (Amalgam and Gold). The values were used to define presets for a 3D colored volume rendering software. CONCLUSIONS: The effects of filling material caused streak artifacts could be distinctively reduced for the assessment of the dental status and a postprocessing algorithm was introduced that allows for 3D color encoded visualization and discrimination of different dental restorations based on postmortem CT data.

Acrylic Resins↗