RT Journal Article
SR Electronic
T1 In Vivo Assay of Folate Receptors in Nonfunctional Pituitary Adenomas with <sup>99m</sup>Tc-Folate SPECT/CT
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1716
OP 1723
DO 10.2967/jnumed.108.061689
VO 51
IS 11
A1 Galt, James R.
A1 Halkar, Raghuveer K.
A1 Evans, Chheng-Orn
A1 Osman, Naema A.
A1 LaBorde, David
A1 Fox, Timothy H.
A1 Faraj, Bajat A.
A1 Kumar, Kush
A1 Wang, Houping
A1 Oyesiku, Nelson M.
YR 2010
UL http://jnm.snmjournals.org/content/51/11/1716.abstract
AB 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, 29–82 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–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–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.