Guest Editorial

Article Outline

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One of the challenges of healthcare in the 21st century is to diagnose and treat diseases in their infancy. Imaging plays an important role in achieving this goal. In nuclear medicine we have the privilege of being able to detect disease-related dysfunction that can occur before anatomic changes can be appreciated. With the emergence of molecular imaging, we are now developing targeted diagnostic and therapeutic agents that are able to visualize functional changes at (sub)cellular levels.

While these significant developments have lead to a major paradigm shift toward functional and physiologic imaging, one of the most significant drawbacks is the fact that, the closer we get from reaching this targeted approach, the fewer anatomic details and landmarks are available for accurate assessment of the metabolic information. Co-registration of separately performed anatomic and metabolic studies has proven feasible and demonstrated the value of combined images. However, improving the anatomic localization of foci of impaired metabolism through software techniques has been hampered by a multitude of technical and logistic difficulties.

Dr. Bruce Hasegawa from UCSF was among the first to understand the unmet need of the medical community. He explored the feasibility of integrating anatomic and physiologic imaging into a single combined functioning unit in the late 1980s, overcoming the main limitations of software co-registration through anatomic and functional images that were obtained in close temporal and spatial proximity in the same imaging session. This further allowed teams of highly talented physicists and engineers in the industry to meet the challenge and progress towards the beginnings of a new technology—hybrid imaging—and specifically developing positron emission tomography/computed tomography (PET/CT) and single-photon emission computed tomography (SPECT)/CT devices.

GE Healthcare's Millennium VG with “Hawkeye,” a dual-head gamma camera with an integrated x-ray transmission system, was the first fully integrated clinical SPECT/CT hybrid system, with Vanderbilt University Medical Center and Rambam Health Care Campus being the first sites to perform clinical studies in 1999. One year later, the first PET/CT scanners, developed by Siemens and GE Healthcare, were installed in the University of Pittsburgh Medical Center, University Hospital in Zurich, Johns Hopkins, and Rambam. Phillips Medical soon joined with additional hybrid imaging devices. The superimposition of SPECT or PET and CT images, without the challenges of co-registration, was a significant technologic advancement and was met with contagious enthusiasm by both physicians and scientists.

Newer generations of hybrid systems utilize multislice CT with improved anatomic resolution, contrast and scanning speed. New PET and SPECT biometrics are being developed and evaluated in large-scale clinical studies, opening a new era of molecular imaging for diagnosis, staging, and treatment response in a variety of diseases. Continuing developments in SPECT technology, including solid-state detectors, are about to change well-established clinical protocols.

This two-part issue of Seminars in Nuclear Medicine has been conceived to respond to a number of specific achievements. Published as we celebrate a decade of hybrid imaging, it also comes a year since the untimely death of Bruce Hasegawa and is, therefore, a tribute and salute from the imaging community to the foresight and vision of this extraordinary scientist.

An additional focus of this seminar is to illustrate that collaboration between institutions can accelerate the scientific progress in developing medical technology and clinical protocols, as was the case for SPECT/CT and PET/CT, opening new avenues for exploring future innovations in medical imaging.

The article on physics and technological aspects of hybrid imaging written by Drs. Patton, Hutton, and Townsend from the Vanderbilt University Medical Center in Nashville, University College London in the UK, and University of Tennessee in Knoxville, provides insight into the technical challenges and solutions that have lead to the development of hybrid imaging devices.

The contribution of Drs. Even-Sapir, Keidar, and Bar-Shalom, from Tel-Aviv Medical Center and Rambam, in Haifa, Israel, authors of early milestone articles on SPECT/CT and PET/CT, demonstrates the improved diagnostic accuracy achieved by this modality and is dedicated to their teacher and mentor, the late Prof. Dov Front.

The article by of Drs. Bockisch, Freudenberg, Schmidt, and Kuwert, from the German University Hospitals of Essen and Erlangen, relies on the cumulative unique expertise of the authors and provides evidence for proven outcomes of PET/CT and SPECT/CT in cancer imaging.

With a large clinical experience reported in numerous publications and guidelines, Drs. Delbeke, Schroder, Martin, and Wahl, from the Vanderbilt University Medical Center in Nashville, Memorial Sloan-Kettering in New York, and Johns Hopkins in Baltimore, take us one step further, demonstrating the value of hybrid imaging in improving therapeutic decisions with a wide range of medical applications.

Although the majority of the articles included in this two-part series are devoted to broad reviews and perspectives on the future, one deals entirely with a specific organ system. Dr. Stephen Scharf has had a unique experience with hybrid imaging of bone disease because of his association with a hospital with a very strong orthopedic practice. Dr. Scharf has accumulated a large and imposing library of images of bone disease and bone injuries using hybrid imaging. His review of this area is a unique contribution based on an impressive clinical experience.

From the University Hospital in Zurich, Switzerland, and Brigham and Women's Hospital in Boston, Drs. Kaufmann and Di Carli, whose combined experience over the last few years allows SPECT/CT and PET/CT to enter the field of noninvasive cardiac evaluation, eloquently summarize how hybrid imaging is now being used beyond assessment of cancer as initially envisioned.

Finally, the outstanding contribution that introduces this first part this seminar, by Dr. Thakur of Jefferson University in Philadelphia, predicting the future role of genomic biomarkers for molecular imaging, and the visionary essay that concludes the two issues by Dr. Cherry of the University of California, Davis, present the latest technological developments in hybrid imaging and plans for the future. These articles provide clear evidence that the next decade will be at least as exciting as the one that preceded it.

We are grateful to all our contributors whom we know and appreciate for their expertise, knowledge, and dedication for many years. Research in hybrid imaging has been successful because we have all joined forces and developed good working relationships within academic institutions all over the world and with partners in the industry, leading to the current state of development of this technology, and its rapid acceptance by the imaging community and referring physicians who treat the patients.

Special thanks go to Drs. Don Blaufox and Lenny Freeman, the tireless Editors of Seminars in Nuclear Medicine, who have made this journal a leading teaching instrument for all who work, or are interested, in our specialty. Their enthusiasm and advice have made this special issue possible—dedicated to 10 years of hybrid imaging and to the memory of our distinguished colleague and friend, Bruce Hasegawa.