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ホームInternational symposium of education for forensic medicine第2回>Lecture 1 Germany

Air in Post Mortem CT – Riddle, Tool, and Clue.

Prof. Dr. Hermann Vogel
Department of Legal Medicine, University Medical Center Hamburg-Eppendorf

Background: PMCT is employed on a wide scale.  In Hamburg, since 2008, more than 6000 PMCT have been made. New methods like MPMCTA have been developed. Procedures adapted to examine the corpse have been developed. At present, we think of procedures, which are adapted to asked questions, and which optimise our resources. This approach shall be demonstrated by showing the potential and the role of air in PMCT.
Material and Method: The Institute for Legal medicine of the University Hospital Eppendorf, Hamburg, has its own 16 slice CT (Philips Imation), since 2008.  Victims of crime, deceased of unknown cause, and deceased patients are regularly examined with PMCT. The PMCT consists of a whole body CT (slice thickness 1mm, pitch 1mm, 180-220mAs and 120-140kV), and CT of the head and the heart (slice thickness 0,8mm, pitch 0,5mm, 180-220mAs, and 120-140kV).  The data are transferred to a radiologist, specialised in forensics since 40 years by teleradiology. In more than 90%, the written report is available the same day. Recently, the role of air in the findings and its contribution to the diagnosis has been analysed systematically. 
Results: During the first years, PMCT had been an additional tool. With growing experience, it became apparent that certain questions are either easier to be answered when the pathologist knows the PMCT beforehand (for example which bones are fractured after a fall of great height), or that some findings would not be documented if PMCT not had been made (for example wrong positioning of tubes, and catheters). Furthermore, it was obvious that small amounts of air were difficult or impossible to localise and demonstrate by autopsy. These small amounts of air can pose a riddle, or a diagnostic clue. Air by itself can be a tool in PMCT diagnostics. 
Riddle: After death, blood outgases. This liberated gas appears in the vessels, which are higher up; in a corpse in prone position, this gas shows up in the liver, the right heart, the ascending aorta, the lumbar aorta, and the inguinal femoral vessels.  This liberated gas has to be differentiated from gas embolism and air replacing intravascular blood after bleeding. Keeping the corps cold does not impede the outgassing.
Tool: Intravascular gas can be used to visualise details of the inner surface of vessels, heart holes, and body cavities. One can examine these inner surfaces with “virtual endoscopy”, a method, which calculates images corresponding to those obtained with an endoscope. Examples are vegetation of cardiac valves, defects of the cardiac septa, and implanted valves. With pneumothorax the rupture of the heart and the rupture of the lung is open to inspection.
Clue: The analysis of the air allows being precise about air embolism as the cause of death. The sequence of stabs can be determined by analysing the air pattern. Air bubbles allow locating stabs into the heart with needles. In the bones, air indicates the stab and its direction. After coronary intervention, air showing up in the left coronary artery, suggests arterial air embolism; this assumption is strengthened by contrast substance imbibition of the myocardium.
Conclusion: In PMCT, air and especially air bubbles indicate findings, which are not available by other approaches. At present, we work on the definition of algorithms/proceedings with PMCT as the primary examine.

  • Education Center for Forensic Pathology and Science Symposium
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