Mechanism of technetium 99m sestamibi parathyroid imaging and the possible role of p-glycoprotein

• Published in: Surgery Vol. 120; no. 6; pp. 1039 - 1045
• Main Authors: Mitchell, Bradford K., Cornelius, Eugene A., Zoghbi, Sami, Murren, John R., Ghoussoub, Rola, Flynn, Stuart D., Kinder, Barbara K.
• Format: Journal Article
• Language: English
• Published: United States Mosby, Inc 01.12.1996
• Subjects: Adenoma - metabolism; Adult; Aged; ATP-Binding Cassette, Sub-Family B, Member 1 - metabolism; ATP-Binding Cassette, Sub-Family B, Member 1 - physiology; Female; Humans; Hyperparathyroidism - diagnostic imaging; Hyperparathyroidism - metabolism; Immunohistochemistry; Male; Middle Aged; Parathyroid Glands - diagnostic imaging; Parathyroid Glands - metabolism; Parathyroid Neoplasms - metabolism; Radionuclide Imaging; Radiopharmaceuticals; Reference Values; Technetium Tc 99m Sestamibi; Thyroid Gland - cytology; Thyroid Gland - metabolism
• ISSN: 0039-6060; 1532-7361
• DOI: 10.1016/S0039-6060(96)80052-3

Background. Localization of parathyroid glands is critical in the treatment of recurrent or persistent hyperparathyroidism. Technetium sestamibi imaging may improve localization; however, the mechanism of visualization of parathyroid tissue remains unclear. On the basis of the chemical structure of sestamibi it has been suggested that p-glycoprotein is involved in the transport of sestamibi across cell membranes. This study was designed to examine sestamibi uptake and retention and p-glycoprotein expression in normal and abnormal parathyroid tissue. Methods. Thirty-two consecutive patients underwent 2-methoxy-isobutyl-isonitrile imaging immediately before parathyroid exploration. Tissue was obtained from normal and abnormal parathyroids and from the thyroid gland. Touch preparations gave rapid confirmation of tissue origin. Specimens were trimmed and weighed, and gamma-emission was counted. Percentage injected dose per gram of tissue was calculated. Immunohistochemistry was obtained with a battery of monoclonal antibodies to identify p-glycoprotein in parathyroid tissue submitted for permanent histologic examination. Slides were graded by a pathologist familiar with immunohistochemistry. Results. Abnormal parathyroid tissue had a higher mean retention of injected dose per gram than did normal thyroid and parathyroid tissue. Immunohistochemistry revealed that abnormal parathyroid tissue expresses less p-glycoprotein. Conclusions. These results suggest that size is not the single determinant of parathyroid visualization and that p-glycoprotein expression may be involved in the mechanism of parathyroid imaging.