"It is advisable for patients to stop caffeine intake for a 24-hour period prior to imaging," said SNM member Medhat M. Osman, M.D., Sc.M., Ph.D., assistant professor in the department of internal medicine's division of nuclear medicine and director of PET at St. Louis University Hospital, St. Louis, Mo. The study, "Correlation Between Myocardial Uptake and Caffeine Intake: Detection With FDG PET/CT," traced the relationship between caffeine intake and myocardial uptake detected by whole-body PET/CT.
PET is a powerful medical imaging modality that noninvasively (nonsurgically) uses special imaging systems and radioactive tracers to produce pictures of the function and metabolism of the cells in the body. CT is an X-ray test that generates a detailed view of the anatomy or structure of organs and tissues in the body. Fused together, PET and CT images can more accurately define a host of diseases processes than can conventional, anatomic-based imaging alone (such as CT and MRI) and can play an important role in cardiac and neurologic imaging.
Most PET scans today are performed with an imaging radiopharmaceutical--most commonly FDG (fluorodeoxyglucose)--that can be tracked by a PET scanner. Where FDG goes in the heart--its uptake into an organ, a tissue, a cell or body fluids--provides a picture of the heart's function. If a person exercises before having a PET/CT scan, more FDG uptake is noted. The researchers found that the same thing happens with caffeine: The heart beats faster when you drink coffee, just as it does when you exercise. Patients who had coffee before their scans had a "significantly higher" myocardial uptake than those with low or no caffeine intake, said Osman. Even average caffeine consumption "may directly affect myocardial uptake," he added.
This is a problem, because an increase in the FDG seen on a scan makes it more difficult to see lesions or read the image if they are in close proximity to the heart, said Osman. By avoiding caffeine and exercise, an individual has a better chance of providing a "good view" of his or her body.
Authors of "Correlation Between Myocardial Uptake and Caffeine Intake: Detection With FDG-PET/CT" are Stephanie M. Anastas, Crystal D. Botkin and Penny E. Yost, all internal medicine, division of nuclear medicine, St. Louis University Hospital, St. Louis, Mo.; Dorina Kallogjeri, Cancer Center Operations; and Medhat M. Osman, internal medicine, division of nuclear medicine, St. Louis University Hospital, St. Louis, Mo.
Technologist Paper 1705
About the Society of Nuclear Medicine
The Society of Nuclear Medicine is holding its 52nd Annual Meeting June 18–22 at the Metro Toronto Convention Centre, Toronto, Canada. Research topics for the 2005 meeting include techniques for the early diagnosis of Alzheimer's disease; advanced imaging for the diagnosis, staging and treatment of cancer; nuclear cardiology; and the collaboration between nuclear medicine and bioengineering in the fight against cancer. SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular imaging/nuclear medicine. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.