Tc 99m pyrophosphate muscle labelling in McArdle syndrome

This paper reports the findings on 2 patients with McArdle syndrome (myophosphorylase deficiency) in whom conventional bone scans with Tc-99(m) pyrophosphate revealed intense muscle labeling following exercise tests. The temporal pattern observed was similar to that seen with other types of muscle damage. The prolonged cramps often occurring with this entity appear to produce muscle damage that is readily demonstrable using conventional bone-scanning techniques.