FIGURE 5. Double-phase parathyroid scintigraphy with ^99mTc-sestamibi in patient with multinodular goiter. (Top left) Image at 15 min shows physiologic early uptake in thyroid gland, with clear focus of increased accumulation at lower pole of left thyroid lobe. (Top right) Late ^99mTc-sestamibi scan shows some residual activity in thyroid gland, with obvious focal ^99mTc-sestamibi retention at lower pole of left thyroid lobe. Second tracer (^99mTc-pertechnetate) was administered after recording delayed ^99mTc-sestamibi scan. (Bottom left) Image obtained by subtracting delayed ^99mTc-sestamibi scan from summation scan recorded after ^99mTc-pertechnetate administration was used to draw profile of thyroid gland, which was then superimposed on delayed ^99mTc-sestamibi scan (bottom right) for better anatomic localization of parathyroid adenoma (confirmed by minimally invasive radioguided surgery).