There are 4 grades of PA with suprasellar extension: 1) Grade A, 0- to 10-mm suprasellar extension occupying the suprasellar cistern; 2) Grade B, 10- to 20-mm suprasellar extension with elevation of the third ventricle; 3) Grade C, 20- to 30-mm suprasellar extension occupying the anterior third ventricle; and 4) Grade D, > 30-mm suprasellar extension beyond the foramen of Monro or a Grade C tumor with lateral extension . There is a 39.5% risk of residual or recurrent tumors after an initial TSS on imaging for Grade C and D adenomas . Based on their prospective study, Honegger et al. reported that vertical intracranial extension was the strongest independent predictor of incomplete resection after TSS for PAs with suprasellar extension . A residual suprasellar tumor can cause postoperative hemorrhage, which can result in compression of the optic pathway and acute hydrocephalus [13, 20, 21]. Mortini et al. reported that complete giant PA removal was obtained in only 13 of 67 patients (19%) after an initial TSS . Swelling and bleeding of a residual suprasellar tumor or sellar hematoma occurred in 8 of 85 patients (9%) treated by TSS. Saito et al. recommended that the intrasellar dead space and sellar floor not be reconstructed in patients undergoing subtotal or partial tumor removal during an initial TSS in an intentionally staged operation, allowing marked descent of the diaphragma sellae and suprasellar tumor, thus avoiding postoperative complications . Zoda et al. reported that an open craniotomy might be selected as the initial operation in cases with the following factors: significant suprasellar extension, lateral extension, retrosellar extension, brain invasion with edema, firm tumor consistency, involvement or vasospasm of the arteries of the circle of Willis, and optic apparatus encasement or optic foramina invasion .
A combined simultaneous transsphenoidal and transcranial approach to large-to-giant PAs has been adopted to maximize tumor excision and lower the risk of swelling and bleeding of the residual tumor [1, 3, 9]. Han et al. reported that a simultaneous open craniotomy approach should be prepared for surgical management of giant PAs, if a tumor had 1 or more of the following characteristics: dumbbell shape; irregular shape with significant subfrontal, temporal, or intraventricular extension; previous surgical treatment; suspicious fibrous consistency; or encasement of the optic apparatus and/or cerebral arteries . Nagata et al. introduced a fully endoscopic combined endonasal-supraorbital keyhole approach for complicated parasellar lesions. They demonstrated that the intraoperative endoscopic view from the supraorbital approach showed the suprasellar pituitary tumor became hyperemic and swollen, with progression of tumor debulking from the transsphenoidal approach . Because neurosurgeons cannot be aware of this phenomenon when using the transsphenoidal route alone, the swelling tumor compresses the surrounding neurovascular structures, resulting in postoperative complications.
In the present study, we demonstrated that PAs had high CBVt and increased vascular density. Our results revealed that we could preoperatively identify patients with a high risk of postoperative hemorrhage from residual tumors based on high CBFt by PCT. Conversely, PAs with low CBFt, even those with Grade C or D suprasellar extension, could be safely removed via TSS as an initial surgery.
Sakai et al. reported that arterial spin-labeled perfusion images from a 3T magnetic resonance scanner reflected the vascular density of nonfunctioning PAs, which may be useful in the preoperative prediction of intra- and postoperative tumor hemorrhage . PCT provides reliable information on tumor vasculature . The linear relationship between attenuation changes on computed tomography and tissue concentration of contrast medium, as well as the lack of confounding sensitivity to flow artifacts, allow PCT to potentially offer a more accurate representation of tissue microvasculature than similar magnetic resonance perfusion studies . Additionally, the use of PCT using a 320-row multidetector computed tomography system in the present study overcame the limitation of limited area of coverage by conventional PCT compared with magnetic resonance perfusion imaging.
The present study has limitations that are inherent to its retrospective design. In addition, our study included a relatively small number of cases of large and giant PAs.