Its main use is for imaging the myocardium (heart muscle). It is also used in the work-up of primary hyperparathyroidism to identify parathyroid adenomas, for radioguided surgery of the parathyroid and in the work-up of possible breast malignancies.
In primary hyperparathyroidism, one or more of the four parathyroid glands either develops a benign tumor called an adenoma or undergoes hypertrophy as a result of homeostatic dysregulation. The parathyroid gland take up Tc99m MIBI following an intravenous injection, and the patient's neck is imaged with a gamma camera to show the location of all glands. A second image is obtained after a washout time (approximately 2 hours), and mitochondria in the oxyphil cells of the abnormal glands retaining the Tc99m are seen with the gamma camera. This imaging method will detect 75 to 90 percent of abnormal parathyroid glands in primary hyperparathyroidism. An otolaryngologist can then perform a directed parathyroidectomy (less invasive than traditional surgery) to remove the abnormal gland.
Tc99m MIBI is also used in the evaluation of breast nodules. Malignant breast tissues concentrate MIBI to a much greater extent and more frequently than benign disease. As such, limited characterization of breast anomalies is possible. Scintimammography Breast-Specific Gamma Imaging (BSGI) has the highest specificity for breast cancer of any imaging test, and has a sensitivity of 66% based on positive biopsy compared to mammography and ultrasound with a 29% positive biopsy.
Following the administration of Tc99m MIBI it collects in overactive parathyroid glands. During surgery, the surgeon can use a probe sensitive to gamma rays to locate the overactive parathyroid before removing it.
The false negative technetium-99m-sestamibi scan in patients with primary hyperparathyroidism: Correlation with clinical factors and operative findings / Discussion
Mar 01, 2003; False negative (FN) results limit the efficacy of technetium-99m-Sestamibi scanning for parathyroid localization. We...