Sunday, 27 November 2011

Medulloblastoma MR Spectroscopy

An 14 yo male with persistent headache, nausea and vomiting.


Description:
A well circumscribed ovoid intra ventricular space occupying mass completely occupying and expanding fourth ventricle, leading to obstructive hydrocephalus.
Signals of mass corresponds to dense soft tissue, isointense to cortical grey matter on T1 and Flair, slightly hyperintense on T2.
No cystic component or marked areas of necrosis.
Restricted diffusion on Dw images.
Lobulated mild enhancement on post contrast T1.
On single voxel MR Spectroscopy at short TE of 35 ms, no peak of NAA at 2.01ppm, no peak of creatine at 3.02 with peak of raised choline at 3.2ppm.

Imaging and MR Spectrocsopy findings are very typical for a Medulloblastoma.

Diagnostic clues:
Dense 4th ventricular mass,
Hyper dense (~90%) on CT with spotty calcification (~20%) ,
Nearly isointense to cortical grey matter on MRI with restricted diffusion on Dw images.
Markedly reduced or no peak of NAA with high choline on MRS implies to non neuronal / Non Glial neoplasm.
May see drop metastasis.
Age group ~75% < 10 years; M > F.

Similar posts:
Medulloblastoma with drop metastasis
Lateral origin medullobastoma

MEDULLOBLASTOMA

Syn: MB, Posterior fossa PNET, PNET – MB,
A highly cellular embryonal cell tumor.
Age group : common in children, ~75% diagnosed by 10 years.
3 times more common in males.

Location:
Intraventricular – 4th ventricular roof is a typical and most common location. A most common posterior fossa tumour in children.
Lateral origin – Cerebellar hemisphere is an atypical location common in older children and adults.

Size vary, average size ranges between 3- 5cm at the time of presentation.
On Non contrast CT, solid 4th ventricle mass, hyperdense, calcifcaiton seen in ~20% cases, small intra tumoural cysts, necrosis in ~50% cases.
On MR signal on T1 iso - hypo intense to cortical grey matter on T1 , iso – hyperintense on T2w and FLAIR. High signal on diffusion attributed to its dense, highly cellular nature.
An associated Obstructive hydrocephalus is common seen in ~ 95% cases.
Usually mild to moderate and homogenous enhancement, may show patchy heterogeneous enhancement due to areas of necrosis.
On MR Spectroscopy, NAA reduced or absent as it’s a non neuronal tumour, raised choline.

1 comment:

rasha elshafey said...

MR spectroscopy of medulloblastoma shows CCC taurine peak at 3.4 ppm and this specific for medulloblastoma