Letter from the Editors

Article Outline

• Copyright

During the past several years, there has been growing utilization of positron emission tomography (PET). A great deal of this has been stimulated by its co-registration with computed tomography (CT) acquired during the same patient visit. These elegant PET/CT fusion studies produce function and anatomic correlative images that may add greater specificity and sensitivity than previously available from a radionuclide study alone. Somewhat overlooked has been the parallel progress along similar lines being made with single-photon emitters (SPECT) and CT.

Procedures with single-photon tracers still constitute the majority of everyday nuclear medicine practice. Many of these include body section (SPECT) studies as an important part of the examination. Examples of this include bone imaging with ^99mTc-MDP, infection studies with ⁶⁷Ga-citrate and ¹¹¹In-WBCs, brain imaging with ^99mTc-ECD or -HMPAO, liver blood pool imaging with ^99mTc-RBCs, tumor receptor imaging with ¹¹¹In-octreoscan, and immunoscintigraphy with ¹¹¹In-prostoscint and other antibodies.

The concept of combining SPECT studies with CT acquired during a single examination has stimulated a great deal of productive basic and clinical research. Several commercial companies now offer these instruments. Drs. O’Connor and Kemp from the Mayo Clinic review the development of various SPECT/CT devices that are now available for clinical use. Problems such as patient motion and partial volume averaging are discussed with commentary directed at how different available devices are dealing with these situations. Important considerations such as attenuation correction, non-registration, scatter, and beam hardening artifacts are discussed as well in this comprehensive review.

The remainder of this issue, as well as the entire January 2007 issue, are devoted to the specific disease processes where SPECT/CT has had a positive impact on diagnostic accuracy. Endocrine and neuroendocrine disease, lung cancer and lymphoma, skeletal disorders, and infection localization are discussed in this issue. Additional important subjects will be reviewed in the January issue. We are grateful for the excellent reviews written by our colleagues. It appears clear that, although starting more slowly than PET/CT, SPECT/CT has many existing and potential areas of clinical application and will significantly add to the diagnostic armamentarium of the nuclear medicine physician.

Hopefully, definitive studies of the specific role of SPECT/CT will continue to emerge as utilization of this approach increases. Regardless of the final outcome, there is a clear necessity for the nuclear medicine physician to become increasing familiar with CT imaging in order to pursue his/her task. Close and cooperative relationships with CT radiologists will be essential to the growth of nuclear medicine during the ensuing decade.