We reviewed 95 cases of patients with pituitary microadenomas diagnosed    by magnetic resonance imaging in two institutions: "Hospital Santa Cruz/Beneficência    Portuguesa de Niterói" and "Clínica X-Labs/Rio de Janeiro".    Our aim was to establish the main type of pituitary microadenoma, incidence    and proximity to the hypophisial stalk, and correlate these findings with clinical    and laboratorial data. A Philips Gyroscan T5 III (0.5 Tesla), a GE Vectra (0.5    Tesla) and a GE Signa (1.0 Tesla) scanners were used to scan the patients with    rapid sequences before and after intravenous administration of paramagnetic    contrast medium (gadolinium). There was a predominance of women with prolactinomas    associated to galactorrhea and hyperprolactinemia. In contrast to the current    literature, we observed that the pituitary stalk was centered in most cases.    Contrast medium injection immediately before scanning is essential to identify    microadenomas. The use of half of the preconized dose of gadolinium is recommended.
                                
                                Keywords: Pituitary microadenomas. Sellar tumors. Magnetic resonance    imaging.