The values of fluid-fluid level in the differential diagnosis of the sellar lesions

Objective This paper aims to interpret the special imaging appearance of "liquid-liquid level" in differential diagnosis of sellar region lesions.Methods The MR imaging appearance and histological features of 266 operated sellar lesions were scrutinized.Results Among all the 266 cases,there are 209 cases of pituitary adenomas (including 88 cases with cystic degeneration,48 cases with fluid-fluid lcvel,and a single fluid level in 24 cases,two fluid levels in 9 cases,more than three levels in 15 cases) ; 35 cases of craniopharyngioma; 20 cases of Rathke cyst; 1 case of epiderrnoid cyst and 2 cases of abscess.The incidences of cystic formation and fluid-fluid level in pituitary adenomas were significantly (P ＜ 0.01) higher than the other sellar region lesions,whereas there were non-significant difference between craniopharyngiomas and Rathke cyst lesions(P ＞ 0.05).Conclusions The signs of fluid-fluid level are most common in pituitary adenomas,especially with multiple fluid levels,and more in non-functional,FSH/LH,PRL,and multi-functional pituitary adenomas.Fluid-fluid levels often suggest the subacute hemorrhage in pituitary adenomas. Key words: Pituitary neoplasms ;  Magnetic resonance imaging;  Diagnosis, differential; Fluid-fluid level