Technetium (99mTc) sestamibi is a lipophilic cation which, when injected intravenously into a patient, distributes in the myocardium proportionally to the myocardial blood flow.

The resulting two sets of images are compared with each other to distinguish ischemic from infarcted areas of the myocardium.

In primary hyperparathyroidism, one or more of the four parathyroid glands either develops a benign tumor called an adenoma or undergoes hyperplasia as a result of homeostatic dysregulation.

A second image is obtained after a washout time (approximately 2 hours), and mitochondria in the oxyphil cells of the abnormal glands retaining the 99mTc are seen with the gamma camera.

An endocrine surgeon can then perform a focused parathyroidectomy (less invasive than traditional surgery) to remove the abnormal gland.

During surgery, the surgeon can use a probe sensitive to gamma rays to locate the overactive parathyroid before removing it.

Malignant breast tissues concentrate 99mTc MIBI to a much greater extent and more frequently than benign disease.

Researchers continue to devote their time to improving the technology, changing scan parameters, and reducing dose to patients.