Differential diagnosis of brain ventricular and subependymal lesions Poster No.:

C-2698

Congress:

ECR 2010

Type:

Educational Exhibit

Topic:

Neuro

Authors:

R. Calandrelli, S. Gaudino, G. M. Di Lella, T. Tartaglione, A. M. Costantini, A. Pedicelli, C. Colosimo; Rome/IT

Keywords:

Subependymal region, MRI, CT

DOI:

10.1594/ecr2010/C-2698

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Learning objectives •

To provide a systematic approach to imaging diagnosis of intraventricular/ subependymal lesions by:

1. 2. 3. 4.

Identifying site of origin Defining lesions extent Assessing growth pattern Correlating imaging and clinical data

•

To propose diagnostic hypotheses and to underline the differential diagnosis issues , facing with heterogeneous and challenging imaging pictures.

Background A lesion may be considered intraventricular if it is found primarily within the ventricular system, causing expansion of the ventricle; therefore, it may be sometimes difficult to establish the exact origin of a lesion, for example to assess if a mass extends from the ventricular wall to the ventricular cavity or vice-versa. Nevertheless, we may classify ventricular lesions in two main categories: those that originate from the ventricular walls (i.e. from the subependymal / subventricular region) and subsequently grow into the ventricle, and those that originate from structures within the ventricular system, such as the choroid plexus. (Fig. 1) on page 4 The differential diagnosis list may be addressed by integrating clinical data (e.g. Patients' age, some inherited specific syndromes), together with morphological (CT/MRI) and some "non-morphological" RM imaging findings (DWI, MRS). The most common pathologies are listed in the tables below, according by preferential site of origin and age.

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Fig. References: R. Calandrelli; Bioimaging and Radiological Sciences, Institute of Radiology, Pol. A. Gemelli, Catholic University of Rome, Rome, ITALY

Fig. References: R. Calandrelli; Bioimaging and Radiological Sciences, Institute of Radiology, Pol. A. Gemelli, Catholic University of Rome, Rome, ITALY

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Images for this section:

Fig. 1: Intraventricular/Subependymal lesions

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Imaging findings OR Procedure details 1 - Lesion Detection Although such lesions are relatively easy to recognize because of the great contrast between these soft tissue masses and the surrounding CSF, they may present many overlapping imaging features. (Fig 1) on page 9 2 - Site of Origin vs. Patients' age Once a lesion has been discovered , the next thing to do is the anatomical localization. First, locate the lesion in the supratentorial or infratentorial compartment and try to establish if it's a true intraventricular or a subependymal one; then, among the most common lesions occurring at that Patient's age, consider their preferential developing sites. (Fig. 2) on page 9

-Ependymomas are more commonly found in the IV ventricle , in children. However, supratentorial ependymomas more commonly intra-axial/extraventricular (Fig 3) on page 10 - Choroid plexus Papillomas/Carcinomas are commonly found in the left lateral ventricle in the newborns/pediatric age, and more frequently observed in patients with Li-Fraumeni syndrome, and Aicardi's syndrome. (Fig 4) on page 11 In adults, They're only exceptionally observed in the supratentorial ventricles, and, less rarely, in the IV ventricle. - Intraventricular Meningiomas most often arise from the lateral ventricles, and are typically found in middle-aged /elderly women (Fig 5) on page 12 - Medulloblastomas (MB-PNETs) typically develop in childhood, usually arising from the roof of the IV ventricle (cerebellar vermis) and then filling and expanding the ventricle (Fig 6) on page 13 - Colloid Cysts typically occur in the anterior portion of the III ventricle/foramen of Monro region and are common found in young adults (Fig 7) on page 14 - Teratomas are commonly seen in the lateral ventricles, above all in newborns, developing from embryonic remnants - Germinomas have a propensity to involve the midline (III ventricle), both infiltrating the ventricular walls and filling the cavity; tipically two lesions may be encountered in

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the posterior and in the anterior recesses of the III ventricle. While in pineal region germinomas the M:F ratio is 10:1, suprasellar germinomas are more common in females (Fig 8) on page 15 - Central Neurocitomas often favour the lateral and the III ventricles, and usually have an attachment to the septum pellucidum. It is usually discovered in young adults (Fig 9) on page 16 - Choroid Plexus Cysts (xanthogranulomas) are benign, bilateral choroid cysts, lined by connective tissue, more often seen in middle-aged pts (Fig 10) on page 17 Intraventricular lesions

-Subependymomas may be found either in the supratentorial or in the infratentorial compartments. They are more frequently found in young adults - The Subependymal Giant Cell Astrocytoma always lies near the foramen of Monro, invades ventricular cavity and it is seen in young patients with the tuberous sclerosis complex (Fig 11) on page 18 - Lymphomas often develop from the periventricular regions, and are found preferentially in middle-aged /elderly patients (Fig 12) on page 19 - Neurocysticercosis is the most common parasitic infection of the central nervous system in immunocompetent individuals, at any age, and seldom localizes in the subependymal compartment - Heterotopic Gray Matter Nodules are congenital abnormal locations of neurons that failed to migrate during the CNS development. Thinning of the adjacent cortex and other malformations often coexist. (Fig 13) on page 20 Subependymal lesions

- Metastases can be found either in subpendymal or intraventricular regions, at any age. (Fig 14) on page 21 Ubiquitarious lesions

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3 - Growth Pattern Different growing modalities suggest different behaviours and aggressiveness degrees. Therefore, it is important to distinguish between an expansive growth (e.g. Papillomas, Meningiomas, Colloid Cysts…), an infiltrative growth (e.g.. MB-PNET, Lymphoma, Germinoma…) or a "plastic" one (Ependymoma, Epidermoid) (Fig 15) on page 22. Rapid developing, aggressive masses (like Gliomas, Choroid Plexus Carcinomas and Metastases) often induce extensive vasogenic edema on the surrounding parenchyma, unlike slow-growing lesions. Then, look for CSF seeding resulting in distant dissemination, especially when suspecting MB-PNETs, Ependymomas, Lymphomas, Choroid Plexus Papillomas/ Carcinomas or Gliomas. When dealing with Intraventricular/Subependymal masses, a crucial finding is Hydrocephalus: Expansive/locally infiltrating lesions often induce obstructive Hydrocephalus when ventricular foramina are obstructed (e.g. colloid cyst , giant cell astrocytoma, ependymomas, metastases, abscesses, neurocitomas, subependimal cysts), or by clots from bleeding (e.g. ependymomas, kidney metastases, cavernomas, choroid plexus carcinoma) or finally by inflammatory processes (e.g., Ventriculitis from ruptured abscess). Typically papillomas appearing in newborns induce hydrocephalus from CSF-overproduction (Fig 16) on page 23.

4 - Characterize Lesions on the basis of CT density and MRI intensity As usual in most brain pathologies, MRI is the best modality for an overall evaluation of ventricular and subependymal lesions; however, CT may be useful in selected instances, being very sensitive and specific for identifying calcium deposits. A basic knowledge of the phenomena underlying signal changes on MRI is very important for characterizing a lesion: -T1 - signal hyperintensity may be related to clotting blood (hemorrhagic ependymomas, neurocitoma, subependimomas, some metastases ) to a high concentration of proteins (as in colloid cysts), to fat (teratomas), sometimes to calcifications (neurocitoma, ependymomas, teratoma, choroid plexus papillomas/ carcinomas, meningiomas), or to paramagnetic substances (e.g. metastatic melanoma) (Fig 17) on page 24.

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-T2 - signal hyperintensity (FSE) is found in most pathologic tissues, and is also useful for showing perilesional edema (may be very extensive in choroid plexus carcinomas, aggressive gliomas, neurocitomas, inflammatory pseudotumours), parenchimal infiltration (ependymomas, lymphomas, glioblastomas), and surrounding gliosis (e.g. induced by cavernous hemangiomas). (Fig 17) on page 24 -T2 sequences may also promptly highlight fluid-fluid levels within the mass from sedimentation of blood products (e.g. within ependymomas and cavernomas), cysticlike degeneration (subependimomas, central neurocitomas), and can finally show a high vascularity within a mass, by demostrating vessels flow voids (e.g.. papillomas, neurocitomas) (Fig 17) on page 24. -T2* - signal hypointensity (GRE) derives from susceptibility effects from calcified components (more commonly seen in ependymomas than in subependimomas, subependymal giant cell astrocytomas, neurocitoma,meningioma, choroid plexus papilloma/carcinoma ) or from presence of haemosiderin (hemorrhagic ependymomas, choroid plexus carcinomas, metastases, neurocitomas, glioblastoma) (Fig 17) on page 24. In doubtful cases, CT imaging may promptly differentiate haemosiderin from calcium deposits. -Post-contrast behaviour, above all, plays an essential role in differentiating pure cysts from neoplastic masses. Neoplasms show a variable and heterogeneous CE (absent, or from mild to intense), depending on the histological features and on the presence of calcifications, bleeding or necrotic/cystic degeneration (Fig 18) on page 25 -Fat Suppression techniques can also help to presence of confirm fatty components.

Some new, "non-morphological" MR techniques may further restrict the differential diagnosis in some instances (Fig 19) on page 26: -MR Diffusion-Weighted Imaging (DWI) is based on the random movement of water molecules in a tissue. Tissues in which water diffusion is reduced demonstrate high DWI signal. These sequences may contribute to differentiate fluid-containing lesions that have a reduced water diffusivity, such abscesses or epidermoid cysts, from those that haven't, like colloid/subependymal cysts. Moreover, high-cellularity tissues (such as that of lymphomas or MB-PNET), also show a low diffusivity and are therefore well highlighted at DWI scans. -MR Spectroscopy (MRS): by detecting metabolites spectra within a lesion, MRS, can help in differential diagnoses, suggesting the degree of aggressiveness of a tumor. Generally, a decrease of the NAA to Cho and of the NAA to Cr ratios has been observed in brain tumors. In the same way, the elevation of lactate and lipid peaks suggests the

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presence of necrosis and an accordingly aggressive behaviour. In selected instances, MRS may present more specific findings: for example, an high ratio of Ala to Cr peaks, when found, is a relatively specific finding in meningiomas, while a high peak of mI has been observed in benign Choroid Plexus Papillomas, but not in carcinomas. -MR Perfusion-weighted imaging (PWI) has very little application in intraventricular lesions assessment. However, it may seldom contribute to distinguish a disease recurrence from radionecrosis.

Images for this section:

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Conclusion The diagnosis of ventricular and subependymal lesions is possible starting with the precise definition of the origin, then estimating patterns of growth and direction, and finally integrating all suitable tissue characterization diagnostic tools with clinical data.

Personal Information Affiliations: Institute of Radiology Dept. of Bio-imaging and Radiological Sciences Catholic University and School of Medicine Rome - ITALY

*A special thank to dr. Emanuele Pravatà for his precious contribution.

References •

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Goergen SK, Gonzales MF, McLean CA. Interventricular neurocytoma: radiologic features and review of the literature. Radiology. 1992 Mar;182(3):787-92. Review. Greenberg MD. Intraventricular lesions. In: Handbook of neurosurgery. 3rd edition. Lakeland: Greenberg Graphics Inc.; 1994. p 203-205. Guermazi A, De Kerviler E, Zagdanski AM, Frija J. Diagnostic imaging of choroid plexus disease. Clin Radiol. 2000 Jul;55(7):503-16. Review. Horská A, Ulug AM, Melhem ER, Filippi CG, Burger PC, Edgar MA, Souweidane MM, Carson BS, Barker PB. Proton magnetic resonance spectroscopy of choroid plexus tumors in children. J Magn Reson Imaging. 2001 Jul;14(1):78-82. Jelinek J, Smirniotopoulos JG, Parisi JE, Kanzer M. Lateral ventricular neoplasms of the brain: differential diagnosis based on clinical, CT, and MR findings. AJR Am J Roentgenol. 1990 Aug;155(2):365-72. Kawaguchi T, Kumabe T, Shimizu H, Watanabe M, Tominaga T. 201TlSPECT and 1H-MRS study of benign lateral ventricle tumors: differential

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