Fluid in the Airway of Nontraumatic Death on Postmortem Computed Tomography Relationship With Pleural Effusion and Postmortem Elapsed Time Masanori Ishida, MD, PhD,*Þ Wataru Gonoi, MD, PhD,* Kazuchika Hagiwara, MD, PhD,* Hidemi Okuma, MD,* Yukako Shintani, MD, PhD,þ Hiroyuki Abe, MD, PhD,þ Yutaka Takazawa, MD, PhD,þ Kuni Ohtomo, MD, PhD,* and Masashi Fukayama, MD, PhDþ Abstract: To evaluate radiographic features of endotracheal/endobronchial fluid in the airway (FA) observed on postmortem computed tomography (PMCT). We studied 164 subjects who died at our hospital between April 2009 and September 2012. Fluid in the airway was considered positive when fluid was identified in the lumen of 1 of the 2 main bronchi in continuity with a segmental bronchus. Pleural effusion and atelectasis/ consolidation of the lung lower lobes were also evaluated. Fluid in the airway was observed in 60 (71%) of 84 subjects with unilateral or bilateral pleural effusion, and in 44 (55%) of 80 subjects without pleural effu- sion (P = 0.029). Of the latter, 41 (93%) had atelectasis/consolidation of the lower lung lobes. Among subjects without pleural effusion, av- erage times after death to PMCT of subjects with and without FA were 501 and 314 minutes, respectively (P = 0.01). Time-course analysis showed that cases with FA on PMCT largely correlated with time after death (R 2 = 0.7966). Fluid in the airway is frequently observed on PMCT in subjects with pleural effusion or atelectasis/consolidation of the lung. No FA in subjects without pleural effusion correlated to shorter times after death. In addition, FA frequency on PMCT increased over time after death. Key Words: postmortem imaging, computed tomography, pleural effusion, atelectasis, consolidation (Am J Forensic Med Pathol 2014;35: 113Y117) T he use of high-resolution imaging techniques such as com- puted tomography (CT) and magnetic resonance imaging in postmortem investigations is beginning to gain a role as an adjunct to more traditional methods in forensic medicine. 1Y3 There are various reports in the literature describing postmortem CT (PMCT) findings in organs such as the brain, lung, heart, and liver. 4Y8 Endotracheal/endobronchial fluid is often observed in PMCT, and the features of endotracheal/endobronchial fluid on PMCT have not been described in detail. Our aim was to inves- tigate endotracheal/endobronchial fluid on PMCT in cases of nontraumatic in-hospital death. MATERIALS AND METHODS Subjects This study was approved by the ethics committee of our institution, and informed consent was obtained from the fami- lies of the deceased. We performed unenhanced PMCT and conventional autopsy on 193 subjects who died because of nontraumatic causes in our tertiary-care academic hospital be- tween April 2009 and September 2012. Exclusion criteria were as follows: (a) age younger than 17 years (n = 10); (b) presence of thoracostomy tube(s) (n = 3); (c) performance of cardio- pulmonary resuscitation, because cardiac massage and endo- tracheal intubation are considered to affect the amount of endotracheal/endobronchial fluid (n = 16). All cadavers were placed in the supine position at room temperature from the time of death until PMCT examination. Conventional autopsy was performed soon after PMCT. Imaging Technique All PMCT studies were performed on a 4-detector-row CT scanner (Robusto; Hitachi Medical Corporation, Tokyo, Japan) in the helical mode in a cephalocaudal direction without using a contrast medium; the cadaver was laid in the supine posi- tion with hands placed on either side. The following routine scanning parameters were used for all investigations: 120 kVp, 200 mAs, and 1.25 pitch factor in all cases with 2.5 Â 4-mm collimation and 2.5-mm section thickness. Axial images were reconstructed with a 350-mm field of view and a 512 Â 512 image matrix from the CT scanner at 1.3-mm intervals. Image Interpretation Images were interpreted in a digital imaging and com- munications in medicine viewer (zioTerm2009; Ziosoft, Inc, Tokyo, Japan) using 2-dimensional axial data sets. Image analysis was performed by 2 board-certified radiologists who were blinded to clinical information; they interpreted the results by consensus. When fluid was identified in the lumen of at least 1 of the 2 main bronchi in continuity with a segmental bron- chus, we defined the finding as positive for fluid in the airway (FA; Fig. 1, AYC). The findings of pleural effusion and atelectasis/ consolidation (Fig. 1B) of the lower lobe of the lung were also evaluated. When the top horizontal level of pleural effusion was higher than the boundary between the anterior and middle column of the vertebral bodies in any of the axial images at the level of the lower lobe, we defined the finding as positive pleural effusion in this study (Fig. 1, C and D). It has been reported that a single area measurement of an axial PMCT image correlates with the volume of pleural effusion. 9 On the basis of this, boundary between the anterior and the middle column of the vertebral bodies in any of the axial images may be considered an acceptable approximate indicator of the volume of pleural effusion. The finding of ORIGINAL ARTICLE Am J Forensic Med Pathol & Volume 35, Number 2, June 2014 www.amjforensicmedicine.com 113 Manuscript received August 10, 2013; accepted December 1, 2013. *Department of Radiology, Graduate School of Medicine, The University of Tokyo; †Department of Radiology, Mutual Aid Association for Tokyo Metropolitan Teachers and Officials, Sanraku Hospital; and ‡Depart- ment of Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. The authors report no conflicts of interest. Reprints: Masanori Ishida, MD, PhD, Department of Radiology, Mutual Aid Association for Tokyo Metropolitan Teachers and Officials, Sanraku Hospital, 2-5 Kandasurugadai, Chiyoda-ku, Tokyo 101-8326, Japan. E-mail: masanoriishida@hotmail.com. This work was supported in part by a grant from the Japanese Ministry of Health, Labor and Welfare for research into ‘‘Usefulness of Postmortem Images as an Ancillary Method for Autopsy in Evaluation of Death Associated With Medical Practice (2008Y2009).’’ Copyright * 2014 by Lippincott Williams & Wilkins ISSN: 0195-7910/14/3502Y0113 DOI: 10.1097/PAF.0000000000000083 Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.