@article {Galt1716, author = {James R. Galt and Raghuveer K. Halkar and Chheng-Orn Evans and Naema A. Osman and David LaBorde and Timothy H. Fox and Bajat A. Faraj and Kush Kumar and Houping Wang and Nelson M. Oyesiku}, title = {In Vivo Assay of Folate Receptors in Nonfunctional Pituitary Adenomas with 99mTc-Folate SPECT/CT}, volume = {51}, number = {11}, pages = {1716--1723}, year = {2010}, doi = {10.2967/jnumed.108.061689}, publisher = {Society of Nuclear Medicine}, abstract = {The objective of this study was to evaluate the in vivo assay of folate receptors in nonfunctional pituitary adenomas using preoperative 99mTc-folate SPECT/CT and Western blot analysis (WBA) of surgical specimens as the standard. Methods: Fifty-six patients (29 men, 27 women; age range, 29{\textendash}82 y) with clinically nonfunctional pituitary adenomas on MRI underwent preoperative imaging using 666 MBq (18 mCi) of 99mTc-folate. SPECT/CT images and whole-body and lateral head planar images were acquired approximately 2 h after injection. Surgical resection took place within a week. WBA on a portion of the excised specimens assessed folate receptor expression in 49 patients. Attenuation-corrected 99mTc-folate SPECT/CT images were assessed qualitatively and quantitatively (maximal adenoma counts to background), with WBA as a standard. Results: Integrated CT was useful for uptake localization and assisted region-of-interest placement. Qualitative interpretation of planar imaging yielded a sensitivity of 81\% and specificity of 72\%. Qualitative SPECT/CT yielded a sensitivity of 94\% and specificity of 61\%. Receiver-operating-characteristic curve analysis of quantitative uptake yielded a tumor-to-background cutoff ratio of 3.5, with a sensitivity of 81\% and specificity of 83\%. Scalp uptake yielded consistent results (over the brain, neck, and choroid plexus) for background when SPECT/CT misalignment artifacts were avoided. Detection of pituitary uptake on anterior{\textendash}posterior and lateral images was hampered by facial uptake, which varied between patients. Conclusion: SPECT/CT of 99mTc-folate is an accurate method of assaying folate receptors in vivo and may provide a quantitative marker for identifying folate receptor{\textendash}positive tumors. This method may also prove beneficial in selecting patients for folate-targeted therapy of clinically nonfunctional pituitary adenomas, for which there is currently no medical therapy.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/51/11/1716}, eprint = {https://jnm.snmjournals.org/content/51/11/1716.full.pdf}, journal = {Journal of Nuclear Medicine} }