Varied microcirculation of pituitary adenomas at rapid, dynamic, contrast-enhanced MR imaging.

Abstract

Rapid, dynamic, contrast material-enhanced magnetic resonance imaging was performed to evaluate the early enhancement patterns of normal pituitary structures, macroadenomas, and microadenomas. A 1.5-T imager with a circularly polarized head coil was used on 40 patients referred for investigation of endocrinopathy, of neurologic deficit, or for follow-up of a previously documented pituitary tumor. The technique provided a temporal resolution of one image per 1.25 seconds, allowing discrimination of primary arterial and secondary portal circulation enhancement phases of pituitary structures and tumors. Arterial-phase enhancement of 16 macroadenomas was observed, suggesting a primary arterial blood supply to these lesions. Five microadenomas showed minimal enhancement in the secondary portal circulation phase. A brief temporal phase was also captured, in which cavernous sinus invasion by tumor was visualized as a "filling defect" within the gadolinium-laden laterosellar venous spaces. The technique reveals the microcirculatory dynamics associated with pituitary adenomas and suggests a dominant arterial blood supply for macroadenomas. It can supplement routine spin-echo imaging for determination of cavernous sinus invasion. Limitations related to section positioning, resolution, and signal-to-noise ratio exist.