FIGURE 3.  Comparison of ^99mTc-sestamibi scans of parathyroid among the 3 clinical groups of PHPT at 5 min (early phase) and 2 h (delayed phase). Accuracy of technique increases in more severely affected patients, approaching 100%. Of patients with severe bone disease (group III), 70% showed increased uptake on early images, in contrast to patients in the other groups, who showed increased uptake only on delayed images.