Minimally invasive post-mortem CT-angiography in a case involving a gunshot wound

Non-contrast post-mortem computed tomography (pm-CT) is useful in the evaluation of bony pathologies, whereas minimally invasive pm-CT-angiography allows for the detection of subtle vascular lesions. We present a case of an accidentally self-inflicted fatal bullet wound to the chest where pm-CT-angiography revealed a small laceration of the anterior interventricular branch of the left coronary artery and a tiny disruption of the right ventricle with pericardial and pleural effusion. Subsequent autopsy confirmed our radiological findings. Post-mortem CT-angiography has a great potential for the detection of vascular lesions and can be considered equivalent to autopsy for selected cases in forensic medicine.

Diagnosis of fatal pulmonary fat embolism with minimally invasive virtual autopsy and post-mortem biopsy

We report a case of a 78-year-old female with a proximal femur fracture caused by an accidental fall who died suddenly 1h after orthopaedic prosthesis insertion. Post-mortem computed tomography (CT) scan and histological examination of samples obtained with post-mortem percutaneous needle biopsies of both lungs were performed. Analysis of the medical history and the clinical scenario immediately before death, imaging data, and biopsy histology established the cause of death without proceeding to traditional autopsy. It was determined to be acute right ventricular failure caused by massive pulmonary fat embolism. Although further research in post-mortem imaging and post-mortem tissue sampling by needle biopsies is necessary, we conclude that the use of CT techniques and percutaneous biopsy, as additional tools, can offer a viable alternative to traditional autopsy in selected cases and may increase the number of minimally invasive forensic examinations performed in the future.

A minimally destructive technique for removing the smear layer from dentine surfaces

OBJECTIVES: To develop a minimally destructive technique for removing the smear layer produced by cutting and polishing specimens of dentine prepared for use in experimental studies, e.g. on occlusion of dentinal tubules by oral health products. The aim was to avoid the damage caused by conventional techniques utilising short exposures to solutions with very low pH. METHODS: Two acetate buffers, pH 5.5, containing different concentrations of calcium and phosphate, with -log(ion activity product with respect to hydroxyapatite) (pI(HA)) of 55 or 56, were tested on slices of dentine using scanning electron microscopy (SEM). RESULTS: A solution which, from previous work, was slightly undersaturated with respect to dentine mineral, with a pI(HA) of 56, was found to remove smear layers produced by cutting and/or polishing after 15 min. However, to reliably remove debris occluding the tubules an exposure time of 2h, followed by brief ultrasonication, was necessary. After 2h treatment with this buffer, only a small amount of demineralization of the surface was detectable by SEM, while calcium and phosphorus were detectable by X-ray dispersive spectroscopy. CONCLUSION: It is possible to remove smear layers, and to open dentinal tubules, by a reasonably short exposure to an acidic buffer which is undersaturated with respect to dentine mineral.

Development of an auditory implant manipulator for minimally invasive surgical insertion of implantable hearing devices

To present the auditory implant manipulator, a navigation-controlled mechanical and electronic system which enables minimally invasive ('keyhole') transmastoid access to the tympanic cavity.

Postmortem imaging-guided biopsy as an adjuvant to minimally invasive autopsy with CT and postmortem angiography: a feasibility study

Although postmortem CT suffices for diagnosing most forms of traumatic death, the examination of natural death is, to date, very difficult and error prone. The introduction of postmortem angiography has led to improved radiologic diagnoses of natural deaths. Nevertheless, histologic changes to tissues, an important aspect in traditional examination procedures, remain obscure even with CT and CT angiography. For this reason, we examined the accuracy of a minimally invasive procedure (i.e., CT angiography combined with biopsy) in diagnosing major findings and the cause of death in natural deaths.

Microneurography in rats: a minimally invasive method to record single C-fiber action potentials from peripheral nerves in vivo

Microneurography is a method suitable for recording intraneural single or multiunit action potentials in conscious subjects. Microneurography has rarely been applied to animal experiments, where more invasive methods, like the teased fiber recording technique, are widely used. We have tested the feasibility of microneurographic recordings from the peripheral nerves of rats. Tungsten microelectrodes were inserted into the sciatic nerve at mid-thigh level. Single or multiunit action potentials evoked by regular electrical stimulation were recorded, digitized and displayed as a raster plot of latencies. The method allows unambiguous recording and recognition of single C-fiber action potentials from an in vivo preparation, with minimal disruption of the nerve being recorded. Multiple C-fibers can be recorded simultaneously for several hours, and if the animal is allowed to recover, repeated recording sessions can be obtained from the same nerve at the same level over a period of weeks or months. Also, single C units can be functionally identified by their changes in latency to natural stimuli, and insensitive units can be recognized as 'silent' nociceptors or sympathetic efferents by their distinctive profiles of activity-dependent slowing during repetitive electrical stimulation, or by the effect on spontaneous efferent activity of a proximal anesthetic block. Moreover, information about the biophysical properties of C axons can be obtained from their latency recovery cycles. Finally, we show that this preparation is potentially suitable for the study of C-fiber behavior in models of neuropathies and nerve lesions, both under resting conditions and in response to drug administration.

A Minimally Invasive Technique for the Detection and Analysis of Pulmonary Fat Embolism: A Feasibility Study*

We investigated the feasibility of postmortem percutaneous needle biopsy (PNB) for obtaining pulmonary samples adequate for the study of pulmonary fat embolism (PFE). Samples of both lungs were obtained from 26 cadavers via two different methods: (i) PNB and (ii) the double-edged knife technique, the gold standard at our institute. After water storage and Sudan III staining, six forensic pathologists independently examined all samples for the presence and severity of PFE. The results were compared and analyzed in each case regarding the vitality of the PFE and its relationship to the cause of death. The results showed that PFE was almost identically diagnosed and graded on the samples obtained via both methods. The discrepancies between the two techniques did not affect the diagnoses of vitality or cause of death related to PFE. This study demonstrates the feasibility of the PNB sampling method for the diagnosis and interpretation of PFE in the postmortem setting.

Minimally invasive postmortem telebiopsy

For the past 10 years, medical imaging techniques have been increasingly applied to forensic investigations. To obtain histological and toxicological information, tissue and liquid samples are required. In this article, we describe the development of a low-cost, secure, and reliable approach for a telematic add-on for remotely planning biopsies on the Virtobot robotic system. Data sets are encrypted and submitted over the Internet. A plugin for the OsiriX medical image viewer allows for remote planning of needle trajectories that are used for needle placement. The application of teleradiological methods to image-guided biopsy in the forensic setting has the potential to reduce costs and, in conjunction with a mobile computer tomographic scanner, allows for tissue sampling in a mass casualty situation involving nuclear, biological, or chemical agents, in a manner that minimizes the risk to involved staff.

A self-developed and constructed robot for minimally invasive cochlear implantation

Conclusion: A robot built specifically for stereotactic cochlear implantation provides equal or better accuracy levels together with a better integration into a clinical environment, when compared to existing approaches based on industrial robots. Objectives: To evaluate the technical accuracy of a robotic system developed specifically for lateral skull base surgery in an experimental setup reflecting the intended clinical application. The invasiveness of cochlear electrode implantation procedures may be reduced by replacing the traditional mastoidectomy with a small tunnel slightly larger in diameter than the electrode itself. Methods: The end-to-end accuracy of the robot system and associated image-guided procedure was evaluated on 15 temporal bones of whole head cadaver specimens. The main components of the procedure were as follows: reference screw placement, cone beam CT scan, computer-aided planning, pair-point matching of the surgical plan, robotic drilling of the direct access tunnel, and post-operative cone beam CT scan and accuracy assessment. Results: The mean accuracy at the target point (round window) was 0.56 ± 41 mm with an angular misalignment of 0.88 ± 0.41°. The procedural time of the registration process through the completion of the drilling procedure was 25 ± 11 min. The robot was fully operational in a clinical environment.