Regional 99m technetium diphosphonate uptake in experimental dog heart infarct: relation to duration and severity of ischaemia.

Regional uptake of 99mTechnetium diphosphonate was compared with regional myocardial blood flow 6, 12 and 24 h after the onset of myocardial infarction in dogs, and with regional creatine kinase depletion 24 h after the onset. Uptake of the imaging agent increased from 6 to 24 h, but no consistent relationship could be demonstrated between regional myocardial blood flow and regional uptake of the diphosphonate nor between uptake and regional creatine kinase depletion at the centre or border of the infarct. In addition, inappropriately high levels of 99m Technetium uptake could be demonstrated in the epicardial layer of the normal tissue surrounding the infarct. We conclude that diphosphonate uptake is not quantitatively related to the severity of ischaemia, and that use of this substance for imaging may over-estimate myocardial infarct size.