Review Article
Background and current status of postmortem imaging in Japan: Short history of “Autopsy imaging (Ai)”

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Abstract

There is a low autopsy rate and wide distribution of computed tomography (CT) and magnetic resonance imaging (MRI) scanners in Japan. Therefore, many Japanese hospitals, including 36% of the hospitals with in-patient facilities and 89% of large hospitals with ER facilities conduct postmortem imaging (PMI), use clinical scanners to screen for causes in unusual deaths as an alternative to an autopsy or to determine whether an autopsy is needed. The Japanese PMI examination procedure is generally referred to as “autopsy imaging” (Ai) and the term “Ai” is now commonly used by the Japanese government. Currently, 26 of 47 Japanese prefectures have at least one Ai Center with scanners that are dedicated for PMI. Here, we briefly review the history of Japanese PMI (Ai) from 1985 to the present.

Section snippets

1985

Dr. Noriyoshi Ohashi, an ER surgeon at Tsukuba Medical Center, started to conduct postmortem CT (PMCT) for the first time in Japan on cases brought into the ER in a state of cardiopulmonary arrest [21].

1995

Dr. Akihiro Takatsu, a forensic pathologist, initiated the development of a digital autopsy method based on digital PMI images, preserving data in a personal computer as a “digital morgue.” He later reported on this method, in 1999 [22], [23].

2000

Imaging examinations are frequently performed in diagnosis and follow-up evaluations for cancer treatment, including chemotherapy and radiation therapy. However, in the terminal stages of the disease, although radical tumor growth may occur, imaging for diagnostic purposes is rarely performed. Thus, there may be great differences between imaging findings while the patient was alive and the autopsy findings.

Dr. Hidefumi Ezawa, a pathologist at the Research Center Hospital for Charged Particle

2001

Dr. Seisaku Uchigasaki, a forensic pathologist, reported the significance of ultrasound examination for the attestation [24], [25]. Eventually, in 2009, the National Police Agency arranged for mobile ultrasound equipment to be located in prefectural police stations throughout Japan and started instructing police officers regarding the use of ultrasound examination.

2003

The Japan Society of Ai was established [26]. Presently, the Society has over 500 members, including medical staff (doctors of radiology, pathology, forensic medicine, critical care and emergency medicine, internal medicine, and surgery) and co-medical staff (radiological technologists, nurses, and clinical technicians).

2004

Members with specialized expertise from the Tsukuba Medical Center and National Institute of Radiological Science published the book “Autopsy imaging (Ai)” [27]. Other pertinent publications included “Guidebook for Interpretation of Ai” [28], “Guidelines for Ai” [29], and “Guidelines for Ai scanning technique” [30] (Fig. 1).

Dr. Hirotaro Iwase, a forensic pathologist, used PMCT in postmortem examinations and reported that at least 20% of the causes of death reported by the police from their

2005

Dr. Seiji Yamamoto, a radiologist at Chiba University, officially initiated the use of PMI for the first time at a university hospital in Japan as an Ai Center [32]. Currently, 26 of the 47 Japanese prefectures have at least one institution with a CT scanner that is solely dedicated to PMI [33], [34]. Most institutions belong to a forensic medicine department, pathology department, or are shared by multiple departments at university hospitals. The Tokyo Medical Examiner's Office plans to

2007

Active discussion increased regarding a death investigation system after an incident involving the assault and death of a young sumo wrestler [35]. The Japanese National Police Agency introduced PMCT to prevent mistaken inquest rulings and designated a national budget to cover PMCT examination costs.

Among approximately 1800 deceased cases (500 in 2007 and 1300 in 2008) that police asked medical institutions to examine using PMCT, two cases were identified by PMCT findings as being criminal

2008

The Japanese Ministry of Health, Labor, and Welfare approved scientific research funds for the “Investigation of PMI to assist autopsy in the detection of death causes related to medical examination and treatment,” covering the period from 2008 through 2010 [37]. The subsequent research report drew the following conclusion: although PMI examination is useful for guiding autopsy, as well as providing additional information for the assessment of the cause of death, it is not a viable alternative

2009

A questionnaire survey by the Japan Medical Association reported that 36% of Japanese hospitals with in-patient wards conducted PMI [16], and the rate of autopsy and the rate of PMI were almost inversely related. For example, of the 47 prefectures in Japan, a functioning MES exists in only four large cities (the 23 wards of metropolitan Tokyo, Yokohama City of Kanagawa Prefecture, Osaka City of Osaka Prefecture, and Kobe City of Hyogo Prefecture). Their respective rankings for autopsy ratio and

2010

There is a shortage of radiologists in Japan capable of interpreting PMI, primarily due to the overall inadequate number of radiologists and their work duties, which are focused on interpreting images in living patients. These circumstances limits radiologists’ experience in PMI, causing them to hesitate to assume responsibility in determining causes of death through interpreting imaging data. To overcome this, an association of board-certified radiologists established the “Ai Information

2011

A committee of the Japanese Ministry of Health, Labor, and Welfare investigating the practical use of PMI in death investigations submitted a report indicating the need to increase the number of radiologists capable of interpreting PMI findings and of radiological technicians capable of conducting appropriate scans [7]. The Ministry started training sessions and began an official approval system for certification of doctors as PMI diagnosis specialists and for radiological technicians as PMI

Present and future

Since 1985, PMCT has been applied in many Japanese ERs and the number of PMCT examinations has increased in cases arriving in a state of cardiopulmonary arrest, in sudden and unexpected deaths occurring in hospitals, in suspected medical malpractice deaths, in cases of natural-cause deaths due to cancer or other diseases, and at the request of the police [45], [46], [47]. Throughout Japan, we estimate that no fewer than 20,000 PMCT procedures are now performed every year.

Interpreting whether

Conflict of Interest

The authors state they have no conflict of interest.

Acknowledgments

This work was supported by a grant from the Daiwa Securities Heath Foundation. The authors thank Ms. Yumiko Moriyama for her assistance in manuscript preparation.

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    This paper is part of the special issue entitled: Postmortem Imaging, Guest-edited by Christian Jackowski.

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