Sequential early and delayed myocardial 99mTc pyrophosphate scans: evaluation of diffuse myocardial uptake.

Of 114 pyrophosphate (PPi) myocardial studies, eleven were selected to assess the significance of diffuse uptake observed in the images obtained early (2-3 h) following injection and compared with delayed scintigrams at 6-24 h. From the results of the late studies the patients were divided into two groups; those with no or minimal residual activity in the delayed study (five cases) and those with approximately the same intensity of delayed scans as in the early study (six cases). No significant abnormalities in cardiac enzymes or the EKG (obtained within 24 h) were noted in the patients of the first group. Cardiac enzymes, EKG abnormalities, indicating myocardial damage, or decreased radionuclide LVEF dysfunction were found in the patients of second group. We concluded that a late image is required in a case of diffuse PPi myocardial uptake in the early image, and myocardial damage may be present if there is persistently diffuse uptake of PPi in the late image.