Magnetic resonance imaging criteria to predict complete excision of parasellar pituitary macroadenoma on postoperative imaging

Abstract

Purpose To evaluate preoperative magnetic resonance imaging (MRI) criteria for their ability to predict the complete removal of parasellar pituitary macroadenoma on the 3-month postoperative MRI. Methods Dedicated pre- and postoperative pituitary MRI studies were reviewed in 49 patients who had undergone transsphenoidal surgery for macroadenomas with potential unilateral parasellar involvement. Twelve preoperative MRI findings and postoperative MRI outcomes were statistically compared. Results Depiction of the inferolateral (positive predictive value [PPV]: 0.6; negative predictive value [NPV], 0.92) and lateral (PPV: 0.65; NPV: 0.85) compartments of the cavernous sinus and the percentage of intracavernous carotid artery encasement (PPV: 0.63; NPV, 1.0 for <50% encasement) were the only criteria significantly predictive of parasellar tumor complete resection. The odds ratios indicated that depiction of the lateral venous or inferolateral venous compartments increased the likelihood of a complete resection by 6 times, whereas for every 25% reduction in intracavernous carotid artery encasement, the chance of a complete resection increased 3.4 times. Conclusion The preoperative MR imaging features that are useful in predicting the complete removal of the parasellar component of a pituitary adenoma as assessed by postoperative MRI are (1) depiction of the lateral and inferolateral compartment of the cavernous sinus and (2) decreasing encasement of the intracavernous carotid artery.

Keywords: macroadenoma; magnetic resonance imaging; pituitary; postoperative.

Fig. 1

Gadolinium-enhanced coronal image illustrating criteria used to exclude cases where parasellar extension was not present. On the left there is depiction of the medial venous compartment (star), no encasement of the intracavernous internal carotid artery, and no crossing of the medial intercarotid line (line). On the right there is parasellar extension of adenoma.

Fig. 2

Gadolinium-enhanced coronal image demonstrating the intercarotid lines and the cavernous sinus venous compartments. The intercarotid lines (left side) were defined as straight lines running between the ipsilateral supraclinoid and cavernous limbs of the carotid artery from their medial edges (medial intercarotid line A), centers (median intercarotid line B), and lateral edges (lateral intercarotid line C).The venous compartments (right side) were superior compartment, 1; venous sulcus compartment, 2; inferolateral compartment, 3; and lateral compartment, 4.

Fig. 3

Gadolinium-enhanced coronal image demonstrating the division of the perimeter of the intracavernous internal carotid artery into twelfths like a clock face, used to score the degree of encasement. There is also bulging of the lateral wall of the cavernous sinus (arrow).

Fig. 4

Gadolinium-enhanced coronal images (A) pre-resection and (B) 3 months postresection. A complete resection was recorded because there is normally enhancing cavernous sinus demonstrated at the site of a preoperative right parasellar tumor.

Fig. 5

Gadolinium-enhanced coronal images (A) pre-resection and (B) 3 months postresection. Residual parasellar tumor was recorded because there is clear residual left parasellar tumor in the same location as that shown on the preoperative imaging (arrow), with similar signal and enhancement characteristics.

Fig. 6

Gadolinium-enhanced coronal images (A) pre-resection and (B) 3 months postresection. An indeterminate resection was recorded because there is residual tissue that differs slightly to that on preoperative magnetic resonance imaging (arrow) at the site of the preoperative left parasellar tumor.