Key words

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-22-4-010

RESEARCH ARTICLE

F-18 Fluorodeoxyglucose (F-18 FDG) Imaging During Acute Myocardial Ischemia.

Malhotra

Nair

Radiation Medicine Centre (BARC), TMC Annexe, Jerbaiwadia Road, Parel, Mumbai-400012.

122007

224

Key wordsStress PETHot spot imagingMemory markerStress SPECT

Aims

Increased rate of glucose utilization during acute myocardial ischemia has been shown in experimental studies. It is not known if F-18 FDG can be used to image this transient metabolic shift during acute ischemia. First aim of the study was to determine if segments showing reversible ischemia on exercise myocardial perfusion single photon emission computed tomography (SPECT) with Tc-99m MIBI showed metabolic shift on a repeat stress F-18 FDG imaging. Second was to evaluate the significance of stress induced F-18 FDG uptake independent of that seen on the SPECT and third was to correlate stress myocardial perfusion SPECT and stress FDG findings independently with angiographic findings.

Materials and Methods

12 male patients, 35–68 year old (median age: 47 years) who showed inducible ischemia on exercise myocardial perfusion SPECT underwent repeat exercise testing within 2 weeks. Positron emission tomography (PET) was performed after injection of 5 to 7 mCi of F-18 FDG, 30 to 45 min post-exercise. Rest FDG PET imaging was performed on a separate day in 9 of 12 patients. SPECT and PET images were assessed visually in standard axis aided by bulls eye circumferential plot for both the studies. Angiography findings were available in 10 of 12 patients.

Results

All patients had enhanced FDG uptake in PET scans corresponding to the areas of inducible ischemia on SPECT studies. Rest FDG PET findings were not similar to stress PET findings in any of the 9 patients in whom rest FDG was also done. When compared with SPECT, F-18 FDG PET imaging revealed additional hot spots in 8 of 12 patients. These additional areas were corroborated on angiography to be harboring significant coronary artery disease (CAD) in the corresponding territories. Thus additional ’hot spot’ on stress PET represented either an FDG uptake in an additional fixed defect on SPECT or an uptake in a territory with known CAD by angiography but not detected by SPECT. When angiography findings were considered as gold standard then sensitivity for CAD detection in LAD, RCA and LCx was 80%, 60%, and 50% respectively for stress myocardial perfusion SPECT while it was 100% for PET in all territories.

Conclusion

Stress induced metabolic shift can be studied by hot spot imaging with F-18 FDG which can serve as a memory marker for acute myocardial ischemia. Stress FDG imaging correlates better with angiography than myocardial perfusion SPECT in evaluation of CAD.

F-18 Fluorodeoxyglucose (F-18 FDG) Imaging During Acute Myocardial Ischemia.

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