Role of MR imaging in the evaluation of pituitary lesions

Abstract

Author(s): Hadi Nakhzari Moghadam, Zeinab Yazdi Sotoodeh* and Afshin Nejad Jahantigh

Pituitary gland plays a central role in body growth, metabolism, and reproductive function. Pituitary lesions, albeit relatively infrequent, can significantly alter the quality of life. The sellar and parasellar region is an anatomically complex area where a number of neoplastic, infectious, inflammatory, developmental and vascular pathologies can occur. Differentiation among various etiologies may not always be easy, since many of these lesions may mimic the clinical, endocrinologic and radiologic presentations of pituitary adenomas. The diagnosis of sellar lesions involves a multidisciplinary effort, and detailed endocrinologic, ophthalmologic and neurologic testing are essential. CT and, mainly, MRI are the imaging modalities to study and characterise normal anatomy and the majority of pathologic processes in this region. Recent advances in neuroimaging helps the radiologists and endocrinologists to study the pituitary region in greater detail. Magnetic resonance imaging (MRI) is the imaging modality of choice for evaluating hypothalamic-pituitary-related endocrine diseases. The radiographic size of sella is not a sensitive indicator of pituitary gland abnormality, as the empty sella may itself lead to enlargement of size. Thus, the plain radiographs have been replaced by crosssectional imaging techniques such as CT scanning and MRI. MRI is the examination of choice for sellar and parasellar pathologies due to its superior soft tissue contrast, multiplanar capability and lack of ionizing radiation. In addition, MRI also provides useful information about the relationship of the gland with adjacent anatomical structures and helps to plan medical or surgical strategy. The aim of MR imaging is to obtain a high-spatial-resolution image with a reasonable signal to noise ratio. Conventional MRI findings were expressed as the ratio of the Signal Intensity (SI) in the lesions to the SI of the normal white matter and the degree of contrast enhancement. There have been substantial advances in pituitary imaging in the last half-century. In particular, magnetic resonance imaging is now established as the imaging modality of choice, providing high quality images of the hypothalamic–pituitary axis and adjacent structures. MRI is the investigation of choice for evaluating hypothalamicpituitary-related endocrine diseases. MRI not only helps in the diagnostic differentiation of these lesions but also provides useful information about the relationship of the gland with adjacent anatomical structures and helps to plan medical or surgical strategy.

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