Normal pituitary and microadenoma T1 signal measurements

Abstract

Background: The most often used technique for detecting pituitary microadenoma is dynamic contrast enhanced magnetic resonance imaging (DCE MRI). However, the high rate of false positivity in its interpretation is a problem due to differential amplification of the normal pituitary. Purpose: The purpose of this study was to see if the precontrast T1 signal intensity ratio (SIR) of lesions identified on DCE MRI could be used to predict the existence of microadenoma. Materials and Methods: We looked at the MRIs of 23 patients who were referred for DCE MRI of the pituitary gland (group 1, 15 patients with diagnosis of pituitary microadenoma; and group 2, patients not clinically labelled as microadenoma). STC were plotted, and T1 SIR was acquired at t = 0 s at the suspect zone of differential augmentation (SIR T) and normal pituitary (SIR P). For each patient, the SIR difference (SIR P SIR T) and relative SIR difference (SIR P SIR T/SIR P) were calculated and compared between the two groups. Results: Patients with microadenoma have a lower mean T1 SIR than those without (P = 0.065). Patients with microadenoma had a greater SIR difference and relative SIR difference (P = 0.003 and 0.005, respectively).