Non-invasive visualisation and volume estimation of maggot masses using computed tomography scanning

There is limited understanding of the actual temperatures that maggots experience during growth. The impact of maggot mass heating on their growth rates cannot be properly factored into maggot growth rate models, thus limiting the accuracy of forensic entomology estimates. One of the major factors contributing to mass heating is the mass size; however, measuring mass volume is problematic as masses quickly become disturbed when probing them to measure their depth and width. Furthermore, many masses are deep within the body cavity and are inaccessible. This study examined the development of a non-invasive means for measuring mass volume using computed tomography (CT) scanning. It was found that CT can be used to visualise and measure the volume of maggot masses, and a series of rules for doing so were established. The level of agreement between mass measurements made by four ‘judges’ using CT volumetric analysis tools produced excellent reliability (ICC > 0.95). This high level of reliability was maintained when applied to masses of different sizes in experimental cups of meat and natural masses of mixed species on human bodies. Entomological features of mortuary CT scans are now routinely reported in forensic entomology casework in Victoria, Australia, as a result of our work.