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- 1. Sellar region; ABRIEF LOOK INTO COMMON pathologies Jack Dalley Jack Dalley MD, BMedImagingSc RT(R) Logan Hospital Brisbane, Australia @Jack_Dalley
- 2. Understand pathophysiologic and clinical features ofsellar and suprasellar lesions 1 2 3 Learning Objectives Identify common sellar region pathologies based on the MR and CT imaging features and their location Detail the sellar and suprasellar region and the importance of imaging
- 3. Sellar Region Pathologies Establishing adifferential diagnosis can be difficult due to the complex structure of the sellar region. Dividing this area into 1. Suprasellar 2. Parasellar 3. Pituitary fossa (sella) can be helpful to identify distinct pathological processes within imaging. 3. Pituitary fossa (sella) 1. Suprasellar cistern 2. Parasellar
- 4. The pituitary gland(Hypophysis) and distal part of the infundibular stalk are located in the sella turcica of the sphenoid bone. The suprasellar cistern is CSF containing space located above the diaphragma sellae, a dural reflection that covers the sella turcica. The supraclinoid internal carotid arteries circle of Willis, superior infundibular stalk, optic nerves, chiasm, and tracts are all located in the suprasellar cistern. The cavernous sinuses, which are lateral to the sella turcica, house the internal carotid arteries as well as CN III, IV, V1/2 (the ocular and maxillary components of the trigeminal nerve), and VI. Anatomy of the Sellar region Anatomy of the Sellar region
- 5. Normal MR Anatomy T1WIthe Posterior pituitary has a bright spot due to storage of vasopressin Anterior pituitary, Infundibulum, and the remainder of the sellar region show intermediate signal intensity on T1W1 Normal Pituitary Gland Size Height varies with age/gender Prepubescent ≤ 6 mm Adult male ≤ 8 mm Adult Female ≤ 9 mm Pregnancy ≤ 12 mm Infundibulum ≤ 3mm Cases: Frank Gaillard rID: 17529
- 6. Sellar Region Pathologies 3. Pituitaryfossa (sella) Pituitary adenoma -Microadenoma -Macroadenoma Rathke cleft cyst Empty sella Lymphocytic Hypophysitis
- 7. Best visualised onpost contrast T1-weighted imaging. Round focus of hypoenhancement in right pituitary. Though dynamic contrast enhanced MRI can improve sensitivity and specificity. Anterior pituitary solid mass, <10mm within the sella Incidence greater in females than males Prolactinoma is the most common functional adenoma Majority vascularised by the hypophyseal portal system which demonstrates classic delayed interstitial contrast diffusion compared to normal tissue Microadenoma Anterior Pituitary MRI Signal Microandenoma MRI Signal Time (Gd) 20 30 60 90 120 150 50 40 30 20 10 0 Adapted from Denis Gardeur, 2016 Case: Frank Gaillard rID: 16787
- 8. Case: Mohamed ElthokapyrID: 148595 Macroadenoma >10mm, composed of adenohypophysial cells. Most common suprasellar extension mass in adults Moderate contrast enhancement. Signal can vary depending on tumour components such as haemorrhage, cystic transformation or necrosis. Characteristic ‘‘figure of eight’’ or ‘‘snowman’’ appearance as diaphragm sellae results in a waist to the mass. These masses can cause superior displacement of the optic chiasm and lateral displacement of the internal carotid arteries. Associations: Acromegaly, MEN 1, McCune- Albright syndrome Case: Frank Gaillard rID: 12838
- 9. Medial Tangent line Intercarotidline Lateral Tangent line Higher Knosp grades (3-4) suggest a lower likelihood of total surgical resection due to the degree of cavernous sinus invasion. Used to predict the likelihood of total surgical resection of pituitary macroadenomas Grade 0: Medial to medial tangent line Grade 1: Between medial tangent and intercarotid lines Grade 2: Between intercarotid line and lateral tangent line Grade 3a & 3b: Tumour above/below the intracavernous internal carotid artery Grade 4: Complete encasement of intracavernous internal carotid artery Modified Knosp Classification 0 1 2 3 3A Superior Cavernous sinus 3B Inferior Cavernous sinus
- 10. Rarely calcifies anddoes not enhance on post contrast images, which helps to distinguish from a craniopharyngioma/adenoma Rathke Cleft Cysts Embryological remnant of the rathke pouch that gives rise to the adenohypophysis. Usually T2 hyperintense cyst, though characteristics vary depending on level of intracystic proteinaceous content. Rathke cleft cyst may contain an intra-cystic nodule (Dot sign) that appears hypointense on T2-weighted images. Case: Frank Gillard rID: 16835
- 11. Empty Sella Cerebrospinal fluid(CSF) filled sella turcica with markedly “flattened” or nonvisualised pituitary tissue Chronic CSF pulsation can lead to eventual expansion of the sella. Associations: Idiopathic intracranial hypertension Case: Anthony Liu rID: 65986 Case: Ian Bickle rID: 24490 The midline positioning of the infundibulum serves as a useful indicator in differentiating an empty sella from a cystic pituitary lesion. This is known as the infundibular sign Case: Ian Bickle rID: 24490
- 12. Lymphocytic Hypophysitis Most commonin women, especially during late pregnancy or the postpartum period. Often shows symmetric enlargement of the pituitary gland and infundibulum Homogeneous post contrast enhancement Characteristic low T2 signal intensity in the parasellar regions: Parasellar T2 Dark Sign Unlike pituitary adenomas, lymphocytic hypophysitis frequently involves the posterior pituitary. This can result in the loss of the normal bright spot Associations: autoimmune conditions- autoimmune thyroiditis, pernicious anaemia monoclonal antibody ipilimumab Case: Dalia Ibrahim rID: 100185 Case: Dalia Ibrahim rID: 100185
- 13. Sellar Region Pathologies 2. Parasellar Meningioma Aneurysm Cavernoushaemangioma Schwannoma Metastatic disease
- 14. Dural tail sign Taperingenhancement extending from the tumour into the adjacent dura mater. Highly suggestive of a meningioma. Can occasionally be seen in other lesions Meningioma Can arise from any of the dural surfaces around the sella Usually show strong homogeneous enhancement after contrast administration. Sunburst sign characteristic vascular supply seen in some meningiomas, when tangential to the dural attachment Arterial Narrowing Can distinguish cavernous sinus extension of a pituitary tumour, which do not typically cause any vascular constriction, and a cavernous sinus meningioma Case: Eid Kakish rID: 63682 Case: Mohamed Elthokapy rID: 85653
- 15. Aneurysm Classic aneurysmal imagingappearance on CT and MR. Giant aneurysms > 2.5 cm A thrombosed aneurysm appears hyperdense on unenhancement CT, hyperintense on T1-weighted and FLAIR sequences. Rim calcification is a supportive feature for aneurysm on CT Pulsation artifacts can also be seen in phase-encoding direction Multiple associations, most relating to abnormal connective tissue disorders Case: Yaïr Glick rID: 90589 Case: Ammar Haouimi rID: 88180
- 16. Sellar Region Pathologies 1. Suprasellarcistern Adamantinomatous Craniopharyngioma Papillary Craniopharyngioma Hypothalamic / Optic chiasm Glioma Hamartoma Germinoma Meningioma
- 17. Distinct entity fromPapillary craniopharyngiomas Adamantinomatous > papillary in children Bimodal distribution (5-15 years of age to 50-70 years of age) CT calcification is key to diagnosis 90% rule: 90% calcified, 90% cystic, 90% peripheral enhancement Variable signal intensities on pre-contrast T1-weighted images due to protein content "motor oil cysts" Adamantinomatous craniopharyngiomas Case: Henry Knipe rID: 42681
- 18. Papillary craniopharyngiomas More commonin the fifth to seventh decades of life. Papillary > Adamantino matous in Adults Tends to have variable T1 iso- to slightly hypointense signal Demonstrate vivid post contrast enhancement in the solid component on MRI and CT. Often lack the cystic appearance and calcifications that are seen in adamantinomatous craniopharyngiomas Normal pituitary gland is seen separate from the mass Case: Frank Gillard rID: 5365
- 19. Germinoma Case: Frank GillardrID: 17966 Type of intracranial germ cell tumour, typically seem in the suprasellar or pineal regions Most common in children and adolescence T1WI iso-hyperintense signal and hypointense on T2WI due to the high nuclear to cytoplasmic ratio (NCR) Characteristic Homogeneous enhancement on T1WI post contrast Loss of the normal posterior pituitary bright spot on T1WI is a typical feature of sellar germinomas. Due to hypercellularity and high NCR, germinomas show restricted diffusion on DWI that results in lower Apparent Diffusion Coefficient (ADC) values than in other sellar specific neoplasms.
- 20. Hypothalamic-optochiasmatic glioma If tumourfollows optic pathway or in a patient with NF1, suspect optic pathway glioma Most commonly seen in children with a strong association with neurofibromatosis type 1 (NF1) Rare in adults though more aggressive. T2WI hyperintense Variable post contrast enhancement Larger masses tend to have a cystic component Calcification not usually seen Case: Vinay Shah rID: 19885
- 21. Hamartoma Mass benign innature often arising from the tuber cinereum On CT they are isodense to gray matter and are often pedunculated though can be sessile in nature MRI; they are isointense on both T1 and T2 sequences and without enhancement Case: Ahmed Abdelrahman rID: 72575 Lack of post contrast enhancement distinguishes hamartomas from other conditions such as craniopharyngiomas or enhancing malignancies like germinomas
- 22. Take Home Points Importanceof Location The anatomical location of a lesion within the sellar region and surrounding structures, including the suprasellar cistern, cavernous sinus, and pituitary fossa, plays a key role in differential diagnosis. Role of Imaging MRI is the main imaging modality used in the evaluation of sellar region lesions. CT is useful in selected cases to detect calcifications, evaluate the relationship of lesions with regional vessels, and assess regional bone. Clinical Correlation Radiographic findings should always be interpreted in the context of clinical presentation, age, gender, and other relevant factors. Some pathologies have known associations with certain demographics, clinical conditions or genetic factors. Continued Learning This presentation offers a baseline understanding, but sellar and parasellar pathologies are a broad topic with many subtleties.
- 23. References 1. Shih R,Schroeder J, Koeller K. Primary Tumors of the Pituitary Gland: Radiologic-Pathologic Correlation. Radiographics. 2021;41(7):2029-46. doi:10.1148/rg.2021200203 2. Ugga L, Franca R, Scaravilli A et al. Neoplasms and Tumor-Like Lesions of the Sellar Region: Imaging Findings with Correlation to Pathology and 2021 WHO Classification. Neuroradiology. 2023;65(4):675-99. doi:10.1007/s00234-023-03120-1 3. Jane Evanson. Radiology of the Pituitary. MDTextcom, Inc. 2020. https://www.ncbi.nlm.nih.gov/books/NBK279161 4. Making Sense of Sellar Region Pathology. Contemporary Diagnostic Radiology. 2015;38(22):8. doi:10.1097/01.cdr.0000472827.42411.67 5. Gardeur D. New Protocol for the MR Imaging of Pituitary Adenomas. Multiphase, Dynamic and Volumetric Imaging on MAGNETOM Skyra The Importance of StarVIBE and CAIPIRINHA Sequences.Siemens MRI