1.5 tesla

Patients underwent pituitary 3-dimensional volumetric MRI (Philips, 1.5 Tesla, Netherlands) before the initial surgery, at which time the largest diameters of the adenomas were measured. Adenomas <10 mm were considered microadenomas, those ≥10 mm were considered macroadenomas, and those >40 mm in diameter were defined as giant adenomas. Follow-up pituitary MRI was performed every 6 months during the first two years and yearly thereafter.

MRI variables of interest and evaluation nomenclature are described in Table 1. Levels from Th12 to S1 were evaluated by the first author using EasyViz (Picture Archiving and Communication System version 7.4.7-263, ON, Canada), and data were entered into a simplified data entry form (EpiData Entry Client version 4.0.2.49, Odense, Denmark) using a fully explanatory data documentation sheet and built-in checks to minimize data entry errors. The MRI system used was Philips 1.5 Tesla. Standard imaging protocol consisted of a sagittal T1-weighted turbo spin-echo (TSE), a sagittal short-tau inversion recovery (STIR), an axial T2-weighted TSE of the three lower lumbar segmental levels and a sagittal Volume Isotropic Turbo spin echo Acquisition (VISTA) enabling reconstruction of semi-coronal series. In a small number of cases other protocols were used, leading to uneven variable-totals (N) in the following analyzes.