Combined Images of Function and Structure:

Positron Emission Tomography (PET) using 18F labelled fluorodeoxyglucose (a radioactive glucose analog) has been playing an important role in clinical oncology covering 40％ of about 700,000 nuclear medicine imaging procedures performed in a year in Japan. For about the past decade, most PET images have been obtained through dual-modality PET/CT imaging that is performed with physically combined PET and CT systems. This supports the intrinsic fusion images of function (PET) with anatomical images (CT). PET/CT images are indispensable for precise diagnosis, localization, treatment planning, and evaluation of treatment effects and recurrence of cancer. The first, fully-combined PET/CT systems were commercialized in 2001 after clinical tests performed by a group headed by David Townsend in 1998 at the University of Pittsburg Medical Center. This article commemorates the first and early efforts which took place at Gunma University Hospital towards a clinically meaningful integration of PET and CT imaging. Namely, we review the origins of the Gunma approach to place PET and CT devices side by side, which enabled combined PET and CT images to be used for clinical diagnosis of brain diseases. The authors acknowledge Prof. Teruo Nagai for establishing this pioneering trial. Two episodes which made this excellent trial known in the international nuclear medicine communities are described together with acknowledgement of the scientific fairness shown by Drs. Townsend and Beyer, pioneers of modern PET/CT.