Review ArticleClinical radiology and postmortem imaging (Virtopsy) are not the same: Specific and unspecific postmortem signs
Introduction
Medical imaging like computed-tomography (CT) and magnetic resonance imaging (MRI) play a major role in clinical medicine. Without evidence based, accurate diagnostic there is no effective treatment. In all disciplines in medicine, radiology got more and more important over the past decades with the development of new techniques (MRI) and better resolutions (CT). Imaging revolutionized forensic medicine not only for diagnostic reasons but also for documentation, which is even applicable in court.
At the beginning of postmortem imaging in 2000 [1], nobody knew the “normal” appearance of all the organs with the sedimentation effect of the blood, the gas formation during decomposition and the altered body temperature. Furthermore, radiologists nowadays are much more used to contrast enhanced imaging methods than to non-contrast examination like postmortem imaging. Although postmortem contrast enhanced examination techniques with promising results have been recently described by Ross et al. [2], [3], [4] the aim of this article is to describe the differences between radiology and non-contrast postmortem imaging (Virtopsy). All basic postmortem changes that may appear in dead people but are perfectly “normal” in this setting shall be described: over the past years we gained more experience and several unspecific postmortem radiological signs could be established [5], [6], [7], [8], [13], [14], [15]. Also postmortem signs that are specific for a certain cause of death will be described [9], [10], [11], [12], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [5], [28], [29], [30], [31], [32], [33], [34], [35], [36].
Section snippets
Technical aspects of Virtopsy
Virtopsy is a specific method, where deceased persons get a classic forensic autopsy combined with postmortem pre-autoptic multislice-computed-tomography (CT) and optional magnetic resonance imaging (MRI) of the whole body without contrast media application [37]. At the beginning of Virtopsy CT was performed on a GE Lightspeed QX/I unit (General Electric, Milwaukee, WI, USA), today it is done on a Somatom 6 unit (Siemens Medical Solutions, Erlangen, Germany). Axial slices are acquired with a
Loss of cortico-medullary differentiation
For the brain the act of dying is patho-physiologically like suffering a stroke: postmortem hypoxia leads to edema formation which obscures the border between white and grey matter. In CT the difference of attenuation between cortex and medulla of the brain decreases rather fast (Fig. 1). This sign is also known in living patients, but it is not compatible with regular brain function. It is usually seen in brain-death patients.
In MRI the cortico-medullary differentiation remains much longer and
Strangulation
Specific signs for strangulation have been shortly established in imaging [11], [25], [26]. There are some common signs in clinical radiology and in postmortem imaging: hemorrhage into the skin, subcutaneous and intramuscular hemorrhage are common (Fig. 8). The sternocleidomastoid and platysma muscle are frequently affected. Hemorrhagic and edematous lymph nodes are a specific sign of strangulation and occur from the venous congestion like the forensic ophthalmologic petechiae. Forensic
Motion artifacts
This rather specific sign for live occurs only in radiology due to respiration, swallowing or beating of the heart during data acquisition. Therefore the border of the diaphragm and the heart can be blurred or doubled (Fig. 9a). Pulsation-artifacts of the aorta may even simulate a dissection membrane (Fig. 9b). These artifacts can be diminished with proper breathing commands and electrocardiogram triggered scans. Obviously these problems do not exist in Virtopsy. Of course, there is need to
Low contrast
Generally in CT the structures of organs and the pathologies are better visible after contrast administration; therefore, abdominal imaging of the living has the higher potential. But MRI helps a lot in detecting edematous pathologies, because of the water-sensibility of the T2 sequences.
“Vanishing” aorta
After fatal hemorrhage the abdominal vessels behave like the big thoracic arteries and veins. Fatal bleeding empties the blood vessel globally. But death generally leads to a loss of intravascular pressure that
Conclusion
The difference in imaging the living or the dead is sometimes unapparent like in the detection of cranial hemorrhage. Sometimes the lack of contrast in postmortem imaging is so obvious like in aortic imaging, where one has difficulties to find an aortic tear. The lack of contrast in postmortem imaging is compensated by an additional modality: a combined CT and MRI analysis helps to increase the accuracy of forensic imaging. A main aim of this article is to give an overview of the several
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