Mercury embolism of the lung and right ventricle revealed by postmortem computed tomography and X-ray analytic microscopy

A man with tattoos was found dead in the sea. Although the body was highly decomposed, his fingerprints identified him as a man in his 40s known to have a history of amphetamine abuse. A week prior to being found, he had stated that he wanted to commit suicide after having made a mistake at work. Video images from security cameras suggested that he drove to the sea alone. Whole-body postmortem computed tomography (PMCT) scans followed by a forensic autopsy were performed. The CT protocol used the following scan parameters: 120 kV tube voltage, 200 mA tube current, 1 rotation per second, 1.25 mm collimation, and a pitch of 0.93. PMCT showed 14 small, high-density particles that appeared to have slight metallic artifacts: 11 particles in the right lobe of the lung and 3 in the wall of the right ventricle (Fig. 1). The particles were 1–2 mm in diameter. The CT values of the particles were 179–1065 Hounsfield units (HU) (mean 517 HU, median 545 HU). Autopsy revealed fluid with high electrolyte concentrations in both pleural cavities. Diatoms were found in both lungs but not in the kidneys. Toxicologic screening tests of blood, muscle, and urine samples, using liquid chromatography-tandem mass spectrometry, were all negative. To identify the high-density particles revealed by PMCT, small specimens that included some of the particles each were extracted, using CT guidance, from formalin-fixed right lung tissue and from right ventricular wall tissue. X-ray fluorescence (XRF) analysis with an X-ray analytic microscope (XGT-5200; Horiba, Kyoto, Japan) was performed to determine the composition of the particles. This machine has a thin (10 lm at its thinnest) glass tube that can narrow the X-ray beam. The beam is focused on a sideby-side basis on the tissue specimen; enabling element mapping by visualizing XRF results point by point with a resolution of 10–100 lm. The XGT-5200 protocol included the following parameters: 100 lm glass tube diameter, 50 kV tube voltage, and 1000 s/frame acquisition time. The XGT-5200 results after scanning one frame are shown in Fig. 2a–d (lung) and Fig. 3a–d (heart). Both analyses detected fluorescence consistent with that of mercury in the same positions where there was high X-ray attenuation on CT findings (Figs. 2e, 3e). Point analysis showed a high-energy spectrum of mercury, whereas there was no mercury spectrum at distant points. None of the spectra of other metals, including those for calcium, iron, and sodium, were significantly changed between these points. Therefore, we concluded that the X-ray absorption & Yohsuke Makino ymakino-tky@umin.ac.jp