====== Magnetic resonance imaging for pituitary neuroendocrine tumor diagnosis ======

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[[Magnetic resonance imaging]] is the most useful [[imaging technique]] in the [[pituitary neuroendocrine tumor diagnosis]]. The popular [[Magnetic resonance imaging sequence]]s are [[spin-echo]] (SE) non-contrast [[T1]]-weighted [[sagittal]] and [[coronal plane]] sections, [[fast spin echo]] [[T2 weighted image]] in [[coronal plane]] sections, and contrast-enhanced T1-weighted coronal plane sections. For simple[[ screening]] [[examination]]s, only non-contrast MRI is performed and contrast-enhanced MRI may not be performed. [[Axial]] T2-weighted or [[fluid-attenuated inversion recovery]] imaging of the whole brain is also recommended to exclude [[incidental]] or concurrent brain lesions.

MRI of the pituitary gland requires some ingenuity because of its small size, its proximity to bone and sinusoidal air, and the proximity of the internal carotid artery. To obtain images with high spatial resolution, slice thickness should be ≤ 3 mm, and the fine matrix (256 × 256 or more) setting with a small field of view (≤ 20 cm) should be used 
((Kanagaki M, Sato N, Miki Y. Pituitary gland and parasellar region. In: Reiser MF, Semmler W, Hricak H, editors. Magnetic resonance tomography. Heidelberg: Springer; 2007. p. 399–432.))
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The basic requirements and elements  should be covered by magnetic resonance imaging 
((Fajardo-Montañana C, Villar R, Gómez-Ansón B, Brea B, Mosqueira AJ, Molla E, Enseñat J, Riesgo P, Cardona-Arboniés J, Hernando O. Recommendations for the diagnosis and radiological follow-up of pituitary neuroendocrine tumours. Endocrinol Diabetes Nutr (Engl Ed). 2022 Nov;69(9):744-761. doi: 10.1016/j.endien.2021.10.014. Epub 2022 Nov 22. PMID: 36428207.))
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Kurosaki reported the clinical experience with MRI for pituitary neuroendocrine tumors(PitNETs)with reference to histopathological findings through a review of the literature. A previous study indicated that the three dimensional-spoiled gradient echo(3D-SPGR)sequence is suitable for evaluating sellar lesions on a postcontrast T1 weighted image(T1WI). This image demonstrates a defined relationship between the tumor and its surroundings, such as the normal pituitary gland, cavernous sinus, and optic pathway. This 3D-SPGR sequence is also suitable for detecting microtumors in corticotroph PitNETs. In somatotroph PitNETs, the signal intensity on T2WI is important to differentiate densely granulated tumors from sparsely granulated somatotroph tumors. In lactotroph PitNETs, distinct hypointense areas in the early phase on T2WI, possibly due to diffuse hemorrhage, indicate pronounced regression of invasive [[macroprolactinoma]]s during [[cabergoline]] therapy
((Kurosaki M. [Neuroimaging of Pituitary Neuroendocrine Tumors]. No Shinkei Geka. 2023 Jul;51(4):634-641. Japanese. doi: 10.11477/mf.1436204796. PMID: 37491060.))
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Because the WHO classification made an important and significant change in the fundamental concept of the disease, the imaging diagnosis (magnetic resonance imaging, computed tomography, and positron emission tomography) of PitNET/pituitary adenoma in detail, considering these revisions as per the latest version of the WHO classification
((Tsukamoto T, Miki Y. Imaging of pituitary tumors: an update with the 5th WHO Classifications-part 1. Pituitary neuroendocrine tumor (PitNET)/pituitary adenoma. Jpn J Radiol. 2023 Aug;41(8):789-806. doi: 10.1007/s11604-023-01400-7. Epub 2023 Feb 24. Erratum in: Jpn J Radiol. 2023 Mar 24;: PMID: 36826759; PMCID: PMC10366012.))
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It is commonly used in the evaluation of [[pituitary neuroendocrine tumor]]s (PAs). However, it has difficulty to locate the lesions sometimes, especially [[microadenoma]]s and/or postoperative recurrent tumors. 
On the MRI they can present various enhancement patterns and other imaging features. About 18% of macroadenomas contain cystic components, and about 20% show foci of hemorrhage, which are usually clinically asymptomatic and diagnosed incidentally in MR imaging.
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Results did not show usefulness of the [[Diffusion-weighted magnetic resonance imaging]] and [[T1-weighted image]]s for assessing the [[consistency]] of [[pituitary macroadenoma]]s, nor as a [[predictor]] of the degree of surgical [[resection]]
((Barbosa MA, Pereira EGR, da Mata Pereira PJ, Guasti AA, Andreiuolo F, Chimelli L, Kasuki L, Ventura N, Gadelha MR. Diffusion-weighted imaging does not seem to be a predictor of consistency in pituitary adenomas. Pituitary. 2024 Jan 25. doi: 10.1007/s11102-023-01377-6. Epub ahead of print. PMID: 38273189.))
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[[Pituitary microadenoma Magnetic resonance imaging]]

[[Pituitary macroadenoma Magnetic resonance imaging]]