For instance, SPECT/CT SRS using 99mTc-HYNIC-octreotide specifically binding to SSTR2 in meningioma can diagnose primary optic nerve sheath meningioma or allow differentiation of meningiomas from inactive pituitary adenomas, which is seemingly elusive by conventional MRI (69, 70). Here, SSTR2 is linked to pituitary gland adenoma.