Forensic Science: DNA Testing, Autopsy Screening, Fingerprint and Blood Spatter Analysis

DNA testing, autopsy screening, fingerprint and blood spatter analysis are methods used in forensic science. These scientific methods are often used to arrest criminals and determine the cause of death in committed crimes. Conventional radiography is one of the oldest imaging techniques used in conjunction with these practices to provide information of skeletal injuries (Grabber S, 2016). However, due to increasing advancements made in radiography, CT and MRI are now more reliable methods. These are used to provide law enforcements and medical professionals with more effective methods to determine the cause of accidental and non-accidental deaths. This paper will evaluate these new procedures and their uses in forensic radiography while primarily focusing on the issue of post-mortem non-accidental injury seen in children.

Non-accidental trauma (NAT) can be defined as any intentional abuse inflicted to either harm or threaten a child (Paul, 2014). NAT is the leading cause of childhood traumatic injury and death in the United States (Paul, 2018). It is estimated that 1,700 children in the United States die of child abuse and neglect annually (National Center for Fatality Review and Prevention, 2011). Studies have shown that cases suspected of NAT often show recurrent attributes such as multiple fractures, metaphyseal fractures, bucket-handle fractures, and fractures of the posterior ribs (Jayakumar, 2010). Moreover, physical abuse is often suspected when a child experiences internal bleeding, showing as subdural bleeding and retinal hemorrhages on the scans (Geddes, 2001) Therefore, forensic radiography is a crucial investigative tool that detects physical abuse in children of pre and post-mortem and combines the use of x-ray, CT and MRI.

Prior to the use of diagnostic imaging in determining the cause of death, conventional autopsy was the common tool used for post-mortem assessment. This tool uses direct inspection, palpation, and tissue specimens to aid in assessment. However, the nature of this procedure is invasive. In addition, it does not allow for a second opinion in court due to the potential loss of evidence from cut tissue. Thus, autopsy is not the most effective method. Because of this, x-ray, post-mortem CT and MRI have been immensely developed and widely used in forensic science and analysis (Yen, 2007).

As noted earlier, x-rays have often been used for post-mortem suspected NAT cases. Although these post-mortem x-rays are significant in identifying skeletal injuries, most cases of NAT are more complex than skeletal injuries alone. These injuries include abdominal and spinal injuries as well (Grabbher, 2016). Conventional radiography is limited in detecting abdominal injury due to its low sensitivity rate and specificity of examinations. A study conducted in 2013, showed that 85% of abdominal injuries were detected by CT. This is due to its high sensitivity and specificity for this type of injury (Larimer, 2013).

Another limitation of post-mortem x-rays is that it is not able to obtain all the necessary images required in the appropriate planes due to the stiffening of the muscle after death. This condition is known as Rigor Mortis (Wagensvald, 2015). This problem is eliminated by PMCT's ability to post process images into different orientations. Multi-planar reconstruction can be used to re-orientate and examine the body parts in different planes (Radiol, 2011). Additionally, post-mortem x-rays

are more time consuming than PMCT, which can be done in a matter of seconds, making it more efficient.

Post-Mortem CT (PMCT) is a non-invasive cross-sectional imaging technique that is increasingly used in determining the death in suspected NAT. Not only is it able to detect skeletal injuries, but also is able to detect more fractures than an autopsy. A study proved this when it detected 28% more injuries than the autopsy did (Daly, 2013). The study continued to say that PMCT is additionally able to classify the blunt force trauma due to its sensitivity. Further, another study done in 2009 concluded that PMCT is able to retrieve valuable information related to brain and spinal cord injuries that are usually missed in an autopsy (Thomsen, 2009).

The advantages of PMCT are evident. However, just like conventional methods, a radiologist must interpret the images obtained. Training and years of expertize is imperative for the accuracy of proper diagnosis. It is important that only the specialized radiologists and pathologists report these post-mortem images. One of the major limitations of PMCT is that is it limited in assessing soft tissue injuries due to CTs poor tissue contrast. Soft tissue injuries are commonly seen on a child who is being physically abused. A study done by Thompson conceded that external or superficial injuries, such as bruising are nonviable using CT (Thompson, 2009). Therefore, CT should not be solely used in the investigation of NAT. In conjunction with PMCT, post-mortem MRI is another tool available that is particularly good at delineating these injuries.

A study published by Korean J Radiol, analyzed five post-mortem cases that underwent an autopsy, PMCT and PMMR. This study concluded that both PMCT and PMMR findings were consistent with four out of the five autopsy cases. However it found that PMMR was the most effective method in evaluating the soft tissue lesions, hemorrhages and bone injuries, all of which are present in NAT victims (Radiol, 2010).

Another study conducted in 2010 compared the two different imaging modalities against an autopsy. It concluded that PMMR was the most effective imaging modality in evaluating traumatic brain injury (Ampanozi, 2010). Brain injury is the most common injury seen in NAT in children, accounting for 64% of the cases (Larimer, 2013).

Given the evidence above, it is evident that PMMR is excellent in determining deaths that involve soft tissue injuries along with hemorrhages. However, one disadvantage of this imaging modality is its limitation in detecting bony details, which are common in NAT victims. These can include metaphyseal lesions and rib fractures (Grabber S, 2016). Perez Rossello concluded that this insensitivity along with high costs, time, prolonged time, low availability, and issues associated with metal artifacts has greatly reduced the significance of PMMR as the frontline imaging modality used in forensic science (Rossello, 2010).

In conclusion, due to the technological advancements made in radiological science, PMCT and PMMR have become increasingly popular tools in forensic science. These imaging modalities allow for the images to be stored digitally and indefinitely. Because of this, tissue samples may not be required from an autopsy for NAT victims. Additionally, the images produced by these modalities can be used in court and can be shown to the audience as evidence with less explicit and tormenting details. These non-invasive methods are often preferred by the victim's family members and more acceptable for cultural and religious beliefs. However, modalities used include autopsy, x-ray, CT and MRI alone or in combination with each other. Ultimately, this will be determined by a case-to-case basis and decided by the radiologist.

Cite this page