Imaging of cardiac 18F-FDG uptake is used in the diagnostic evaluation of residual viable myocardium. Although, originally, hibernating myocardium was identified by a mismatch between perfusion defect and relatively preserved 18F-FDG uptake, at present several studies propose that 18F-FDG distribution can also be used alone for this purpose. Nevertheless, even severe myocardial 18F-FDG uptake defects are frequently observed in cancer patients without any cardiac disease. The aim of this study was to retrospectively analyze global and regional 18F-FDG cardiac images of 49 consecutive cancer patients free of cardiac diseases who submitted to 3 PET scans under fasting conditions. Methods: Images were acquired with a high-resolution PET/CT scanner. Three-dimensional regions of interest were drawn on the fused PET/CT images to measure the maximal standardized uptake value of the left ventricular myocardium (SUVMyo) as well as the average SUV of the left ventricular blood (SUVLV) and of the liver (SUVLiver). Analysis of regional myocardial 18F-FDG uptake was performed on a subsample of 26 patients by an automatic recognition of endocardial and epicardial borders and subdividing the left ventricle in 20 segments. Regional 18F-FDG distribution was defined as the percentage of SUVMyo in each region. Results: SUVMyo as well as SUV LV and SUVLiver did not change on average throughout the studies. This stability was not caused by a persistent pattern of myocardial 18-FDG distribution. Rather, it was associated with important variations in both directions over time. Regional 18F-FDG distribution was largely heterogeneous in all 3 studies, with a variation coefficient in each patient of 18% ± 7%, 18% ± 5%, and 17% ± 5%, respectively. An 18F-FDG uptake of 10% in 76 and in 116 of 468 segments, respectively. Conclusion: The large spatial and temporal heterogeneity of the myocardial metabolic pattern, in cancer patients free of any disease, suggests a word of caution on the use of 18F-FDG alone as a diagnostic tool for myocardial viability.
- Cardiac uptake
- Whole-body PET/CT
ASJC Scopus subject areas
- Radiological and Ultrasound Technology