Clinical brain tumor of MRIPresentation Transcript
Clinical brain tumor of MRI 放射診斷科孫柏齡 2007.04.20 地點 : 放射診斷科討論室
17-year-old female with a clinical suspicion of cerebellar mass.
Your diagnosis is
A T1W image (Fig. 1) shows a hypointense, approximately 7cm x 4cm mass in the right cerebellar hemisphere, with a moderate amount of mass effect on the 4th ventricle and cerebellum.
The mass is hyperintense on the T2W image (Fig. 3).
The cystic portion of the mass has signal intensity similar to CSF on the T1W images and T2W images, but is hyperintense to CSF on the proton density weighted image (Fig. 2) due to increased protein content.
Following Gadolinium administration, T1W images (Fig. 4-6) show intense homogeneous enhancement of a mural nodule in the superior aspect of the mass.
Although septations within the mass show faint enhancement, the cystic portion of the mass does not show enhancement.
Juvenile pilocytic astrocytoma.
Cerebellar juvenile pilocytic astrocytomas are the most common infratentorial neoplasm in the pediatric age group.
Although they commonly form well-defined lobular masses which contain cysts and a vascular mural nodule, they may occasionally present a solid mass without a cystic component and may simulate other pediatric posterior fossa masses.
They have an increased incidence in type I neurofibromatosis.
They have an excellent prognosis following complete resection.
The differential diagnosis includes medulloblastoma and ependymoma in a child.
3-year-old presents with headache and ataxia.
Your Diagnosis is?
Axial CT image demonstrates a right cerebellar and fourth ventricle mass which is somewhat higher in attenuation than the remaining brain parenchyma.
In addition, there is marked dilatation of the temporal horns indicating hydrocephalus.
Axial T1 and T2 weighted images as well as a sagittal image following the intravenous administration of contrast demonstrates an approximately 4 cm fourth ventricular mass with probable extension toward the outlets of the fourth ventricle.
There is very little enhancement following the intravenous administration of contrast.
Ependymomas are the third most common brain tumor in children and account for approximately 15% of posterior fossa malignancies.
They classically arise from ependymal cells lining the fourth ventricle. Commonly, the tumor expands the fourth ventricle and extends through the foramen of Magendie and through the foramina of Luschka.
The tumors are often calcified and may demonstrate a large cystic component.
Inhomogeneous enhancement is usually seen. Because of their location, seeding throughout the subarachnoid space can be seen.
Supratentorial ependymomas, however, are usually more aggressive and have a poorer prognosis.
As stated above, ependyomomas are the third most common posterior fossa tumor in childhood behind juvenile pilocytic astrocytomas and medulloblastomas.
10-year-old presented with 10 days of vomiting, unsteady gait, slurred speech, headache, and diplopia.
Your diagnosis is
A sagittal noncontrast T1W image (Image 1) reveals a mildly hypointense mass arising in the 4th ventricle with expansion posteriorly to displace and distort the vermis.
An axial T1-weighted image after contrast (Image 2) demonstrates the loss of definition of the peripheral borders of the enhancing 4th ventricular mass.
No additional abnormalities in the periventricular or subarachnoid space are identified.
The mass is hyperintense to gray and white matter on an axial T2-weighted image (Image 3). There is a shunt under the right occipitotemporal scalp.
Medulloblastoma represents about 25% of childhood intracranial tumors, with approximately 50% presenting in the first decade.
Medulloblastoma occurs only in the posterior fossa, although it has been grouped with histologically similar tumors arising elsewhere as a primitive neuroectodermal tumor (PNET).
Medulloblastoma generally involves the 4th ventricle and vermis, with a lateral location more common in the desmoplastic variant and in older patients.
On MR, medulloblastoma involves the 4th ventricle and vermis, although eccentric extension to involve the cerebellar hemispheres is not rare.
It is nonspecifically hypo- to isointense on T1W images and hyperintense on T2W images.
No Yes(Luschka, Magendie) No Foraminal spread 60-80% 15% 10-20% Cyst formation 10-20 2-10 5-12 Age Bright Intermediate Intermediate T2WI Hemispheric 4th ventricle ependyoma Vermis Origin Uncommon common Uncommon Calification Nodule enhance, cyst dose not Mininal Moderate Enhancement Hypo Iso Hyper Unenhanced CT Astrocytoma Ependymoma Medulloblastoma
What is the most common infratentorial neoplasm in the pediatric age group?