====== Intracranial germ cell tumor magnetic resonance imaging ======

General imaging features include 


T1: isointense to grey matter

T2: isointense to grey matter

T1 C+ vivid contrast enhancement 

germinomas tend to be homogeneous

[[DWI]]: restriction is common especially for germinomas due to high cellularity

[[ADC]] values are higher than found in [[pineoblastoma]]

[[SWI]]: hemorrhage is common in non-germinomatous germ cell tumors
((Borja MJ, Plaza MJ, Altman N, Saigal G. Conventional and advanced MRI features
of pediatric intracranial tumors: supratentorial tumors. AJR Am J Roentgenol.
2013 May;200(5):W483-503. doi: 10.2214/AJR.12.9724. Review. PubMed PMID:
23617516.
))

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The role of T2*-based MR imaging in intracranial germ cell tumors (GCTs) has not been fully elucidated. The aim of a study was to evaluate the susceptibility-weighted imaging (SWI) or T2* gradient echo (GRE) features of germinomas and [[nongerminomatous germ cell tumor]]s (NGGCTs) in midline and off-midline locations.

Morana et al. retrospectively evaluated all consecutive pediatric patients referred to our institution between 2005 and 2016, for newly diagnosed, treatment-naïve intracranial GCT, who underwent MRI, including T2*-based MR imaging (T2* GRE sequences or SWI). Standard pre- and post-contrast T1- and T2-weighted imaging characteristics along with T2*-based MR imaging features of all lesions were evaluated. Diagnosis was performed in accordance with the SIOP CNS GCT protocol criteria.

Twenty-four subjects met the inclusion criteria (17 males and 7 females). There were 17 patients with germinomas, including 5 basal ganglia primaries, and 7 patients with secreting NGGCT. All off-midline germinomas presented with SWI or GRE [[Hypointensity]]; among midline GCT, all NGGCTs showed SWI or GRE [[Hypointensity]] whereas all but one pure germinoma were isointense or hyperintense to normal parenchyma. A significant difference emerged on T2*-based MR imaging among midline germinomas, NGGCTs, and off-midline germinomas (p < 0.001).

Assessment of the SWI or GRE characteristics of intracranial GCT may potentially assist in differentiating pure germinomas from NGGCT and in the characterization of basal ganglia involvement. T2*-based MR imaging is recommended in case of suspected intracranial GCT
((Morana G, Alves CA, Tortora D, Finlay JL, Severino M, Nozza P, Ravegnani M,
Pavanello M, Milanaccio C, Maghnie M, Rossi A, Garrè ML. T2*-based MR imaging
(gradient echo or susceptibility-weighted imaging) in midline and off-midline
intracranial germ cell tumors: a pilot study. Neuroradiology. 2017 Nov 11. doi:
10.1007/s00234-017-1947-3. [Epub ahead of print] PubMed PMID: 29128947.
)).