In vivo manganese MR imaging of calcium influx in spontaneous rat pituitary adenoma.

Abstract

BACKGROUND AND PURPOSE:

Rapid uptake of the calcium analog manganese (Mn2+) into spontaneous pituitary adenoma during MR imaging of aged rats generated the hypothesis that neuroendocrine tumors may have a corresponding increase in calcium influx required to trigger hormonal release. A goal of this study was to investigate the potential for clinical evaluation of pituitary adenoma by MR imaging combined with administration of Mn2+ (Mn-MR imaging).

MATERIALS AND METHODS:

Mn-MR imaging was used to characterize the dynamic calcium influx in normal aged rat pituitary gland as well as spontaneous pituitary adenoma. To confirm the validity of Mn2+ as a calcium analog, we inhibited Mn2+ uptake into the olfactory bulb and pituitary gland of normal rats by using the calcium channel blocker verapamil. Rats with adenomas received fluorodeoxyglucose-positron-emission tomography (FDG-PET) scanning for characterization of tumor metabolism. Mn2+ influx was characterized in cultured pituitary adenoma cells.

RESULTS:

Volume of interest analysis of the normal aged pituitary gland versus adenoma indicated faster and increased calcium influx in adenoma at 1, 3, 11, and 48 hours. Mn2+ uptake into the olfactory bulb and pituitary gland of normal rats was inhibited by calcium channel blockers and showed dose-dependent inhibition on dynamic MR imaging. FDG-PET indicated correlation between tumor energy metabolism and Mn2+ influx as well as tumor size.

CONCLUSION:

These results indicate that adenomas have increased activity-dependent calcium influx compared with normal aged pituitary glands, suggesting a potential for exploitation in the clinical work-up of pituitary and other neuroendocrine tumors by developing Mn-MR imaging for humans.

• Authors: D J Cross, J A Flexman, Y Anzai, T Sasaki, P M Treuting, K R Maravilla, S Minoshima
• Journal: AJNR. American journal of neuroradiology (AJNR Am J Neuroradiol) 2007 Nov-Dec Vol. 28 Issue 10 Pg. 1865-71 ISSN: 0195-6108 [Print] United States
• PMID: 17925377 (Publication Type: Journal Article)

Chemical References

• Calcium Channel Blockers
• Contrast Media
• Radiopharmaceuticals
• Fluorodeoxyglucose F18
• Manganese
• Growth Hormone
• Verapamil
• Calcium

Topics

• Aging (metabolism)
• Animals
• Calcium (metabolism)
• Calcium Channel Blockers (pharmacology)
• Contrast Media
• Dose-Response Relationship, Drug
• Fluorodeoxyglucose F18
• Growth Hormone (metabolism)
• Image Processing, Computer-Assisted
• Magnetic Resonance Imaging
• Male
• Manganese
• Pituitary Gland (metabolism)
• Pituitary Neoplasms (metabolism, pathology)
• Positron-Emission Tomography
• Prolactinoma (metabolism)
• Radiopharmaceuticals
• Rats
• Rats, Sprague-Dawley
• Tumor Cells, Cultured
• Verapamil (pharmacology)