Letter from the Editors

Article Outline

• Copyright

More than 95% of the clinical positron emission tomography imaging studies being performed in the United States and throughout the world utilize fluorine-18 (¹⁸F)-fluorodeoxyglucose (FDG). However, it also is likely that this practice will undergo significant change within the next several years because of the anticipated approval of several new ¹⁸F-labeled agents.

It is unlikely that medical centers, private laboratories and offices will consider purchasing cyclotrons to produce very short half-lived nuclides like carbon-11 (T_1/2 = 20 min), nitrogen-13 (T_1/2 = 10 min) or oxygen-15 (T_1/2 = 20 min). Therefore, fluorine-18 (T_1/2 = 109 min) will continue to be the major radiolabel used in clinical practice because of its availability from commercial sources. It then follows that new agents labeled with ¹⁸F would be the most feasible approach to exploring a variety of metabolic functions in addition to the currently available study of glucose metabolism with FDG. Although it has provided considerable clinically important information about glucose metabolism, FDG’s major shortcoming remains the non-specificity of its findings. It is with these thoughts in mind that the editors decided to put together the current issue devoted to ¹⁸F agents other than FDG. We would like to thank Dr. Sandi Kwee from Honolulu, HI, for offering useful suggestions for both inspiring this issue and recommending several of the authors. Although the emphasis is on ¹⁸F, positron emitting isotopes of gallium, copper, and bromine, as well as some others, offer the promise of developing into labels that will be practical for general use.

The introductory article by our New York colleague, Dr. Shankar Vallabhajosula, provides a superb overview of the great versatility of fluorine-18 in labeling many different agents. Each of these agents has a role in various aspects of metabolism in a variety of tumors as well as some benign pathologic processes. Choline and thymidine derivative images provide general oncologic probes into cellular proliferation and metabolism while estradiol more specifically looks at metabolic changes in breast cancer patients. Excellent reviews in these areas are provided by Dr. Kwee and some international associates, Dr. Vesselle and colleagues in Seattle, WA, and Drs. Sandararajan, Mankoff, and colleagues, also in Seattle. Tumor hypoxia provides an additional way to monitor activity and response to therapy. ¹⁸F-Fluoromisonidiazole (FMISO) is a unique positron agent that has been developed to study this aspect of tumor metabolism. Lee and Scott from Melbourne, Australia, share with us their interesting work using this agent.

In the area of neurologic diagnosis, ¹⁸F-DOPA has shown great early promise not only in the study of movement disorders, but also in brain tumors, neuroendocrine disorders, and possible dementia. Drs. Seibyl, Chen, and Silverman provide a superb “cross country” review of this exciting agent over this wide range of indications.

Finally, we have an improved cortical bone scan that is made available with the use of ¹⁸F-fluoride. Dr. Einat Even-Sapir and her team in Tel Aviv, Israel, have now utilized this positron agent for several years and have produced extraordinary images for us to appreciate.

In presenting this truly “cutting edge” issue of Seminars in Nuclear Medicine, we are most indebted to all of the authors. We trust that our readers will enjoy these remarkable articles as much as we have. It will certainly serve as an important reference source for the next few years.