Abstract: Objective To study the imaging characteristics of maxillary sinus effusion in drowned bodies, to explore its morphological characteristics and value in the diagnosis of the cause of death, and to provide objective evidence to support the study of virtual anatomy of drowning. Methods The 154 postmortem CT examination cases （31 cases of drowning, 123 cases of non-drowning） of Beijing Public Security Bureau Forensic Center in 2019 were collected. The bodies of all cases were scanned by multi-layer spiral CT before double-blind reading by clinical imaging experts. Maxillary sinus of corpses with maxillary sinus effusion in imaging findings was punctured. The detection rate of maxillary sinus effusion was calculated. The CT value and volume of maxillary sinus effusion were measured on 3D DICOM workstation. Results The detection rate of maxillary sinus effusion in the drowning was 100%, the shape was horizontal liquid level, the volume was 1.2-11.2 mL, the CT value was 6.08-19.02 Hu, with an average value of 12.85 Hu. The detection rate of maxillary sinus effusion in non-drowning was 19.51% （24/123）, the shape was wavy or irregular, and there were bubbles inside, the volume was 0.4-13.4 mL, the CT value was 23.68-77.75 Hu, with an average value of 42.08 Hu. The differences in CT value between the two groups had statistical significance. Conclusion The postmortem CT examination method can be used to observe the shape and measure the CT value of the maxillary sinus effusion in the bodies in water, which can be an auxiliary examination method for identification of drowning.

Key words: forensic pathology, death from drowning, computed tomography （CT）, maxillary sinus, effusion