I Intracranial Lesions



10.1055/b-0034-75773

2 Ventricles and Cisterns(Table 2.1 – Table 2.4)





























Table 2.1 Lateral ventricles: common mass lesions

Age


Foramen of Monro


Trigone and Atrium


Lateral Ventricle, Body


Adult


Colloid cyst


Cysticercosis


Meningioma


Choroid plexus cyst


Neuroepithelial cyst


Central neurocytoma


Metastasis


Neuroepithelial cyst


Cysticercosis


Ependymoma


Glioblastoma


Metastasis


Central neurocytoma


Cysticercosis


Child (> 5 y)


Giant cell astrocytoma


Pilocytic astrocytoma


Cysticercosis


Ependymoma


Choroid plexus cyst


Choroid plexus papilloma


Choroid plexus carcinoma


Hamartoma/tuberous sclerosis


Gray matter heterotopia


Cysticercosis


Ependymoma


Pilocytic astrocytoma


Hamartoma/tuberous sclerosis


Gray matter heterotopia


Cysticercosis


Child (< 5 y)


Giant cell astrocytoma


Pilocytic astrocytoma


Cysticercosis


Choroid plexus papilloma


Choroid plexus carcinoma


Cysticercosis


Choroid plexus papilloma


Choroid plexus carcinoma


Primitive neuroectodermal tumor (PNET)


Teratoma Cysticercosis




























Table 2.2 Common lesions in the third ventricle

Age


Foramen of Monro


Anterior Recess


Third Ventricle, Body


Third Ventricle, Posterior


Adult


Colloid cyst


Metastases


Cysticercosis


Pituitary adenoma


Meningioma


Metastasis


Aneurysm


Craniopharyngioma


Lymphoma


Cysticercosis


Glioma


Cysticercosis


Pineal tumor


Glioma


Vascular malformation


Cysticercosis


Child


Giant cell astrocytoma


Pilocytic astrocytoma


Cysticercosis


Germ cell tumor


Langerhans cell histiocytosis


Glioma


Craniopharyngioma


Cysticercosis


Choroid plexus papilloma


Glioma


Cysticercosis


Pineal tumor


Glioma


Vascular malformation


Cysticercosis

















































































Table 2.3 Lesions in the fourth ventricle

Lesions


CT Findings


Comments


Child


Astrocytoma


Low-grade astrocytoma: Focal or diffuse mass lesion usually located in the cerebellar white matter or brainstem with low to intermediate attenuation, with or without mild contrast enhancement. Minimal associated mass effect. May extend into ventricles.


Often occurs in children and adults (age 20ā€“40 y). Tumors comprised of well-differentiated astrocytes. Association with neurofibromatosis type 1; 10-y survival common; may become malignant.


 


Juvenile pilocytic astrocytoma subtype: Solid/cystic focal lesion with low to intermediate attenuation, usually with prominent contrast enhancement. Lesions located in the cerebellum and brainstem. May extend into ventricles.


Common in children; usually favorable prognosis if totally resected.


 


Gliomatosis cerebri: Infiltrative lesion with poorly defined margins with mass effect located in the white matter, with low to intermediate attenuation; usually no contrast enhancement until late in disease.


Anaplastic astrocytoma: Often irregularly marginated lesion located in white matter with low to intermediate attenuation, with or without contrast enhancement. May extend into ventricles


Fig. 2.1


Diffusely infiltrating astrocytoma with relative preservation of underlying brain architecture. Imaging appearance may be more prognostic than histologic grade; ~2-y survival.


Intermediate between low-grade astrocytoma and glioblastoma multiforme; ~2-y survival.


Medulloblastoma (primitive neuroectodermal tumor of the cerebellum)


Fig. 2.2


Circumscribed or invasive lesions; low to intermediate and/or slightly high attenuation; variable contrast enhancement; frequent dissemination into the leptomeninges and/or ventricles.


Highly malignant tumors that frequently disseminate along CSF pathways.


Ependymoma


Fig. 2.3


Circumscribed spheroid or lobulated infratentorial lesion, usually in the fourth ventricle, with or without cysts and/or calcifications; low to intermediate attenuation; variable contrast enhancement; with or without extension through the foramina of Luschka and Magendie.


Occurs more commonly in children than adults; two thirds infratentorial, one third supratentorial.


Metastatic tumor


Single or multiple well-circumscribed or poorly defined lesions involving the brain stem and cerebellum, skull, dura, leptomeninges, ventricles, choroid plexus, or pituitary gland; low to intermediate attenuation, usually with contrast enhancement, with or without bone destruction, with or without compression of neural tissue or vessels. Leptomeningeal tumor-drop metastasis often best seen on postcontrast images.


May have variable destructive or infiltrative changes involving single or multiple sites of involvement.


Hemangioblastoma


Fig. 2.4


Circumscribed tumors usually located in the cerebellum and/or brainstem; small contrast-enhancing nodule with or without cyst, or larger lesion with prominent heterogeneous enhancement with or without vessels within lesion or at the periphery; intermediate attenuation; occasionally lesions have evidence of recent or remote hemorrhage. May extend into ventricles.


Multiple lesions occur in adolescents with von HippelLindau disease.


Choroid plexus papilloma or carcinoma


Fig. 2.5


Circumscribed and/or lobulated lesions with papillary projections, intermediate attenuation, usually prominent contrast enhancement, with or without calcifications. Locations: atrium of lateral ventricle (children) > fourth ventricle (adults), rarely other locations such as third ventricle; associated with hydrocephalus.


Rare intracranial neoplasms, Magnetic resonance imaging (MRI) features of choroid plexus carcinoma and papilloma overlap; both histologic types can disseminate along CSF pathways and invade brain tissue.


Adult


Metastatic tumor


Single or multiple well-circumscribed or poorly defined lesions involving the skull, dura, leptomeninges, brainstem, cerebellum, ventricles, choroid plexus, or pituitary gland; low to intermediate attenuation, usually with contrast enhancement, with or without bone destruction, with or without compression of neural tissue or vessels. Leptomeningeal tumor often best seen on postcontrast images.


May have variable destructive or infiltrative changes involving single or multiple sites of involvement.


Hemangioblastoma


Circumscribed tumors usually located in the cerebellum and/or brainstem; small contrast- enhancing nodule with or without cyst, or larger lesion with prominent heterogeneous enhancement with or without vessels within lesion or at the periphery; occasionally lesions have evidence of recent or remote hemorrhage; may extend into ventricle.


Occurs in adolescents, young and middle-aged adults. Lesions are typically multiple in patients with von Hippel-Lindau disease.


Astrocytoma


Low-grade astrocytoma: Focal or diffuse mass lesion usually located in the cerebellum or brainstem with low to intermediate attenuation, with or without mild contrast enhancement. Minimal associated mass effect. May extend into ventricles.


Often occurs in children and adults (age 20ā€“40 y). Tumors comprised of well-differentiated astrocytes. Association with neurofibromatosis type 1; 10-y survival common; may become malignant.


 


Anaplastic astrocytoma: Often irregularly marginated lesion located in the cerebellum or brainstem with low to intermediate attenuation, with or without contrast enhancement. May extend into ventricles.


Intermediate between low grade astrocytoma and glioblastoma multiforme; ~2-y survival.


Ependymoma


Circumscribed spheroid or lobulated infratentorial lesion, usually in the fourth ventricle, with or without cysts and/or calcifications; low to intermediate attenuation, variable contrast enhancement; with or without extension through the foramina of Luschka and Magendie.


Occurs more commonly in children than adults; two thirds infratentorial, one third supratentorial.


Choroid plexus papilloma or carcinoma


Fig. 2.6a, b


Circumscribed and/or lobulated lesions with papillary projections, intermediate attenuation, usually prominent contrast enhancement, with or without calcifications. Locations: atrium of lateral ventricle (children) > fourth ventricle (adults), rarely other locations such as third ventricle; associated with hydrocephalus.


Rare intracranial neoplasms; CT and MRI features of choroid plexus carcinoma and papilloma overlap; both histologic types can disseminate along CSF pathways and invade brain tissue.


Epidermoid


Well-circumscribed spheroid or multilobulated, extra-axial ectodermal inclusion cystic lesions with low to intermediate attenuation, no contrast enhancement, with or without bone erosion/destruction. Often insinuate along CSF pathways; chronic deformation of adjacent neural tissue (brainstem, brain parenchyma). Commonly located in posterior cranial fossa (cerebellopontine angle cistern, fourth ventricle) > parasellar/middle cranial fossa.


Nonneoplastic congenital or acquired extra-axial off-midline lesions filled with desquamated cells and keratinaceous debris; usually mild mass effect on adjacent brain; infratentorial > supratentorial locations. Adults: men = women; with or without related clinical symptoms.


Cysticercosis


Single or multiple cystic lesions in the brain, meninges, or ventricles.


Acute/subacute phase: Low to intermediate attenuation, rim with or without nodular pattern of contrast enhancement, with or without peripheral edema.


Chronic phase: Calcified granulomas.


Caused by ingestion of ova (Taenia solium) in contaminated food (undercooked pork); involves meninges > brain parenchyma > ventricles.

Fig. 2.1 Astrocytoma. Axial image shows the tumor within the pons.
Fig. 2.2 Medulloblastoma. Axial image shows the tumor involving the vermis with extension into the fourth ventricle, resulting in obstructive hydrocephalus. The tumor has slightly high attenuation.
Fig. 2.3 Ependymoma. Axial image shows a tumor in the fourth ventricle that has mostly intermediate attenuation, as well as a small zone with low attenuation.
Fig. 2.4 Hemangioblastoma, von Hippel-Lindau disease. Axial postcontrast image shows multiple enhancing nodular hemangioblastomas in the cerebellum, the largest of which is associated with a tumoral cyst.
Fig. 2.5 Choroid plexus carcinoma. Postcontrast image shows an enhancing tumor in the fourth ventricle.
Fig. 2.6a, b Choroid plexus papilloma. Axial CT image (a) reveals a lesion in the fourth ventricle that shows contrast enhancement on axial T1-weighted magnetic resonance imaging (b).




























Table 2.4 Excessively small ventricles

Lesions


CT Findings


Comments


Normal variant


Small ventricles with normal appearance of brain parenchyma and presence of CSF in subarachnoid spaces and cisterns.


Normal variation.


Postshunt/overshunting


Small, slitlike ventricles (with or without shunt tube present).


Small ventricular size can result from acute or chronic overdrainage of ventricles with shunts.


Increased intracranial pressure


Small ventricles with effacement of subarachnoid spaces, with or without decreased attenuation in brain parenchyma; cerebral edema.


Ventricular size usually does not correlate well with intracranial pressure.


Pseudotumor cerebri


Normal shape but small ventricles, with or without mild prominence of intracranial subarachnoid spaces, with or without prominence of fluid in optic nerve sheath complex.


CT with contrast provides a role in excluding intracranial tumors involving the brain or leptomeninges.

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Jul 5, 2020 | Posted by in GENERAL RADIOLOGY | Comments Off on I Intracranial Lesions
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