Citi analyst Adam Spielman believes that health care will become increasingly automated by artificial intelligence in the coming years. The market for AI-assisted diagnostic tools is expected to quadruple to US$4-billion in the next four years, benefiting a wide variety of companies including Microsoft Co., NVIDIA Corp. and the health care division of General Electric Co. AI has been more accurate than human radiologists for a decade, according to Citi, and is challenging doctors’ skills in oncology and stroke recognition. The potential for AI in medical fields is vast. Microsoft, for instance, just paid US$20-billion for a company called Nuance…