Characterization of fluid in facial sinuses on post-mortem CT in case of death by drowning

Recent statistics show that drowning deaths are a reality in Switzerland. Although drowning remains a diagnosis by exclusion for forensic pathologists, post-mortem multidetector computed tomography (PMCT) is a real complementary resource to establish the cause of death. The aim of this study was to determine whether the sinuses' fluids visualized in post-mortem MDCT in case of drowning have specific characteristics that can be related to the submersion process and provide an additional element to the diagnosis of death by drowning. A few studies exist on the subject, but none of them compared putrefied bodies and drowned cases. A balanced dataset was retrospectively collected of 108 cases of natural death, putrefied bodies and drowned cases at the University Center of Legal Medicine in Geneva. For each paranasal cavity, the fluid and sinus were segmented in the slice with largest liquid quantity to derive liquid-to-sinus surface ratio (LR), and mean density (MD) in Hounsfield units (HU) of the fluid when present. For all sinuses, the MD was significantly different between putrefied and drowned groups. The average LR was statistically different for frontal and maxillary sinuses. Using cut-off values as Youden indices from ROC curves, promising specificities (Sp) and sensibilities (Se) were obtained, using single (e.g., frontal sinus: LR cut-off = 0.15: Sp = 76%, Se = 68%; MD cut-off = 44,55HU: Sp = 93%, Se = 64%, or maxillary sinus: LR cut-off = 0.14: Sp = 56%, Se = 86%; MD cut-off = 34,91HU, Sp = 65%, Se = 85%) or all (logistic regression: Sp = 80%, Se = 92.6%) measurements. This study identified potential leads for discrimination of drowning cases from natural deaths and putrefied bodies.