Caffeine and exercise can prevent clear PET and CT imaging of heart
13 July 2005
St. Louis, USA. Consumption of caffeine before a positron emission
tomography (PET) or computed tomography (CT) scan of the heart can increase
the amount of chemical tracer in the heart and obscure the images.
According to research by Dr Medhat M. Osman, Assistant Professor in the
Division of Nuclear Medicine, Department of Internal Medicine, and Director
of PET at Saint Louis University Hospital, patients who need a positron
emission tomography (PET)/computed tomography (CT) procedure to evaluate
known or suspected malignancies should not drink coffee. Dr. Osman presented
his study at the Society of Nuclear Medicine’s annual conference in Toronto,
Canada, in June.
His research traces the relationship between caffeine intake and
myocardial uptake, which is the amount of tracer used during PET/CT that can
be detected by the whole-body scans.
Most PET scans today are performed with an imaging radiopharmaceutical —
most commonly FDG (fluorodeoxyglucose), which is a tracer that goes into the
heart to provide a picture of the organ’s function on PET scans. If a person
exercises before having a PET/CT scan, the faster heart beats cause more FDG
to appear in the heart region, obscuring the view. The research found that
caffeine caused the same effect because it increases the rate of heart beat.
This is a problem, because an increase in the FDG in the heart seen on a
scan makes it more difficult to see lesions close to the heart, says Dr.
Osman. Patients who had coffee before their scans had a “significantly
higher” myocardial uptake than those with low or no caffeine intake, says
Dr. Osman. Even average caffeine consumption “may directly affect myocardial
uptake,” he added. By avoiding caffeine and exercise, an individual has a
better chance of providing a “good view” of their body’s condition.
More information: http://www.slu.edu