Table 1. Corticotropinomas have increased GLUT1 expression compared to the surrounding normal gland.

A blinded analysis of histopathology revealed that 9 out of 10 pituitary adenomas had increased GLUT1 expression. Adjacent normal pituitary tissue was available for 3 patients which were all negative for GLUT1 expression. Despite GLUT1 overexpression, no immediate SUV changes were appreciated in patients that underwent simultaneous CRH-stimulation and ¹⁸F-FDG PET, presumably due to delayed effect on glucose uptake.

	GLUT1 Expression	Normal Adjacent Tissue	Non-CRH / CRH-Stimulated PET	Non-CRH SUV Max	CRH-stimulated SUV Max
Case 1	+++	-	Positive	12.8	12.8
Case 2	+++	NA	Negative	4.3	4.3
Case 3	+	NA	Positive	11.6	11.6
Case 4	++	NA	Negative	4.3	5.3
Case 5	++	NA	Negative	3.7	3.6
Case 6	+++	NA	Positive	21.1	11.1
Case 7	++	NA	Negative	4.7	4.3
Case 8	+	-	Positive	6	6
Case 9	-	NA	Positive	7.5	7.3
Case 10	+++	-	Negative	5	4.3

⁺weak immunoreactivity,

⁺⁺moderate immunoreactivity,

⁺⁺⁺strong immunoreactivity,

^-no immunoreactivity.

Abbreviations: ¹⁸F-FDG PET - ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET, GLUT1 – glucose transporter 1, NA – not available.