Cardiac PET scanning offers a reliable, noninvasive method for evaluating coronary abnormalities in very young patients, starting in the first month after birth. Researchers from the University of California, Los Angeles used FDG and ammonia-13 PET studies to assess myocardial viability in children with suspected heart defects, and tested PET's effectiveness against histologic findings.
In this study, nine children aged 14 days to 12 years who had undergone heart surgery were scanned with resting ammonia-13 and FDG PET. Angiograms and a pathologic tissue analysis were available for all patients either at heart transplant or postmortem, said Dr. Miguel Hernandez-Pampaloni in a presentation at the Society of Nuclear Medicine conference in June in St. Louis.
The myocardium was defined as normal if the ammonia uptake was graded as normal on a 5-point scale, Hernandez-Pampaloni said. If the ammonia and FDG uptakes had concordant match patterns, the myocardium was deemed nonviable. A mismatch between ammonia uptake and glucose metabolic activity also was considered nonviable.
The results were compared to angiographic perfusion scores from a 4-point scale and correlated with histopathology.
The results showed exact agreement between regional myocardial perfusion and angiography in 162 segments analyzed. The correlation between the perfusion segments and histopathology was 87% in patients with normal ammonia-13 uptake, 60% in those with moderate uptake, and 75% in patients with severely reduced uptake.
In 79% of the segments where there was no fibrosis, both the PET scan and histopathology detected viable myocardium. The absence of viable tissue was correlated with both techniques in 84% of the segments with any amount of fibrosis.
"We can conclude that PET is useful to assess coronary obstructions in infants and even neonates because of high spatial resolution. Metabolic PET imaging also identifies myocardial viability in pediatric patients," Hernandez-Pampaloni said.
A group from Guy’s Hospital in London reached a similar conclusion in a paper published in a recent issue of Pediatric Cardiology. In this case, ammonia-13 and PET were used to evaluate myocardial perfusion after an arterial switch operation in 11 patients, ages one to four. The results were correlated with patterns of coronary artery anatomy, electrocardiogram, and echocardiography.
PET scanning demonstrated normal distribution of myocardial perfusion before and after stress in all but one patient, and can be considered a "reliable noninvasive method for evaluation of myocardial perfusion in small children," the group concluded (Pediatric Cardiology, Mar-Apr.2000, Vol 21:2, pp.111-118).
By Shalmali Pal
AuntMinnie.com staff writer
July 25, 2000
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