Background and current status of postmortem imaging in Japan: short history of "Autopsy imaging (Ai)".

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.