CT and MRI scan

At 1 week before and after surgeries, CT plain scan of paranasal sinus was performed separately using 256-slice spiral CT scanner (Discovery Ultra, GE Corporation). Scan parameters were consecutive scan along with the axis position, layer thickness of 0.625 mm with an interval of 0.625 mm, scan time of 1.2 s, FOV of 250 mm × 250 mm, and matrix of 512 × 512. All patients received CT scan in a supine position. Infraorbital line was regarded as the base line. Scan area ranged from the mandible to the upper frontal sinus. With multiple planar reconstruction (MPR) reconstructed using CT reconstruction software, the three-dimensional image models of the sella turcica were calculated in the environment of Mimics 15.0 software (Materialise Inc., Belgium).

At 1 week before and after surgeries, T1WI, T2WI, and T1WI contrast-enhanced MRI was performed separately using 3.0 T MRI system (Trio Tim, SIE corporation). MRI parameters were: layer thickness of 1.0 mm, FOV 250 mm × 250 mm, matrix 256× 256 and scan time of 6 min. Contrast-enhanced MRI was performed via intravenous injection of Gd-DTPA at a dosage of 0.2 mmol/kg body weight at a flow speed of 3.6 ml/s. Using INFINITT software (Seoul, South Korea), the localization of tumor were identified from the adjacent tissues. The maximal tumor diameter and the tumor area (S) of each layer were calculated automatically in coronal position. All tumors were divided into micro-, macro- and giant –adenoma (as illustrated in Fig. ​Fig.1),1), and the tumor volume was calculated [15].

Schematic diagram of the maximal tumor diameter evaluated by enhanced coronal MRI (44.65 mm represents the maximum diameter of this pituitary adenoma)

Based on the method proposed by Knosp et al. [16] the degree of tumor invasiveness was classified into grades from 0 to 4: (1) grade 0, the tumor margin did not pass the tangent of the medial aspects of the supra- and intracavernous ICA; (2) grade 1, the tumor margin did not pass a line between the cross-sectional centers of the carotid arteries, the so-called “intercarotid line”; (3) grade 2, the tumor margin extended beyond the intercarotid line, but does not extend beyond or tangent to the lateral aspects of the intra- and supracavernous ICA; (4) grade 3, the tumor margin extended lateral to the lateral tangent of the intra- and supracavernous ICA; (5) grade 4, the CSICA was completely encased by tumor tissues. If the Knosp classification grade higher than 3, the tumors were defined as the invasive pituitary adenoma.