MAGNETIC RESONANCE IMAGING O PITUITARY AND PARASEIIAR LESIONS

Abstract

The pituitary gland is a complex neuroendocrine organ involved in the control of a variety of homeostatic mechanisms. It resides in the sella turcica and bordered on .both sides by the cavernous sinuses, which harbor carotid arteries, 3rd, 4th , 5th and 6th cranial nerves. For this reason, the pituitary gland parasellar region is an intricate crossroad of endocrine, neural, vascular and skeletal structures. Many clinical syndromes are a result of lesions involving the sella tmcica and neighboring structures. Imaging is crucial because clinical evaluation frequently cannot localize the lesion accurately. Therefore patients with symptoms and signs of pituitary axis dysfunction or visual field deficits are frequently re1eJTed for diagnostic imaging procedure.

Computed tomO!,>Taphy (CT) was the first modality to display soft tissue cross sectional anatomy. It was a significant imaging advancement in the evaluation of tl1e sellar area and it soon became the preferred method of assessment (Chambers et aL, 1982; \Davis et aL, 1984).

However, it does have a number of significant limitations. Computed tomography has the hazards of radiation and contrast enhancement. Beam hardening artifact secondary to bone and dental an1algam can be a problem . CT also has limited soft tissue resolution. For example, the carotid artery within ilie cavernous sinus often cannot be separated distinctly.