Differentiation of sellar lesions by use of combination of 68Ga-DOTATATE and 18F-FDG PET/CT

Objectives The aim of this study was to define whether the combinaition of 68Ga-DOTATATE and 18F-FDG could be helpful for the differential diagnosis in the sellar lesions.

Methods We evaluated 86 consecutive subjects suspicion of sellar lesions, including primary pituitary adenoma(n=34,PPA), recurrent pituitary adenoma(n=35,RPA),Rathke’s cleft cyst(n=5,RCC),pituitary infection (n=3,PI) , pituitary lymphocytic hypophysitis (n=2,PLH), langerhans cell histiocytosis(n=3,LCH), meningiomas (n=2),craniopharyngioma(n=2), who underwent both FDG PET/CT and DOTATATE within one week. The final diagnosis was based on the pathology and follow-up.

Results DOTATATE detected higher-uptake tissue which showed minimal FDG uptake confirmed residual pituitary gland in 33 patients with RPA,,whereas cannot detect pituitary gland in two cases. FDG detected hypermetabolic tissue in 34 patients with RPA confirmed tumors ,whereas cannot detect tumor in one case.DOTATATATE uptake in residual tumor is variable: 25 show moderate uptake ,9 show minimal uptake and 1 show void uptake,whereas the degree of uptake in moderate group is lower than residual pituitary gland(P=0.005). 34 PPA showed intense two tracer uptake.2 meningiomas showed intense uptake of DOTATATE and minimal uptake of FDG.These two tracer uptake in cyst content was absent with RCC. 3 PI and 2 PLH showed extension to the sellar and minimal uptake of two tracer. 3 LCH showed moderate two tracers uptake in the involved region.2 craniopharyngioma showed moderate two tracers uptake in the solid component.

Conclusions The combination with FDG and DOTATAE can be valuable in the differentiation pituitary adenoma and meningiomas , pituitary adenoma and pituitary inflammatory, while have to referenced to morphological imaging in some lesions.Furthermore, this technique allows differentiation recurrent pituitary adenoma and normal pituitary gland from postoperative formation.