Brainstem gliomas are usually non pilocytic, low
On imaging studies they are most commonly solid and
infiltrating, with variable contrast enhancement.
Tumors intrinsic to the brainstem are biologically
more aggressive than pilocytic astrocytomas arising in
the optic pathways or cerebellar hemispheres, with
most patients dying within two years. Occasionally
cystic pilocytic astrocytomas may arise in this region.
History: 3 year-old boy with walking difficulty.
Diagnosis: Low grade astrocytoma, WHO I
ACR Code: 152.3631
Large T2 hyperintensity mass in clivus with enhancement after
contrast administration on T1 weighted image.
History: 34 year-old male with difficulty walking.
Diagnosis: Chordoma, clivus.
ACR Code: 121.327
-- A chordoma is a primary malignancy arising from remnants of the
notochord, most commonly seen in sacrum and the clivus.
-- MRI will show heterogenous, bright signal on T2 weighted
images. There is usually post-contrast enhancement.
-- Differential diagnoses include myeloma, aneurysmal bone cyst,
giant-cell tumor, metastatic renal cell cancer, etc.
There are bilateral T2 hyperintensities in the basal ganglia and
caudate on the FLAIR and T2 weighted images.
Bright signals are seen in bilateral basal ganglia and caudate on diffusion weighted
images which are dark on corresponding ADC map, indicative restricted diffusion
from cytotoxic edema.
Post-contrast T1 weighted images show no significant enhancement.
History: 72 year-old male with progressive dementia and
Diagnosis: Creutzfeldt-Jacobs Disease.
ACR Code: 148.2079
-- Creutzfeldt-Jakob disease (CJD) is a rare and fatal
neurodegenerative disease, possibly caused by a peion infection.
Patients are usually aged between 50 and 75 and typical clinical
features include a rapidly progressive dementia associated,
myoclonus and a characteristic electroencephalographic pattern.
Neuropathological examination reveals cortical spongiform change,
hence the term `spongiform encephalopathy'.
-- MRI usually shows characteristic basal ganglia abnormal T2
hyperintensities with restricted diffusion pattern.
-- Differential diagnosis is relatively short, including CJD, familial
striatal degeneration, Leigh disease, and Wilson's disease .
The axial FLAIR image as well as the coronal T1 and T2
weighted MR images demonstrate absence of the septum
pellucidum and hypoplasia of the optic chiasm. The coronal T2
weighted image demonstrates small/hypoplastic optic nerves.
-- The septum pellucidum may be completely (64%) or partially
(36%) absent which results in a squared-off appearance of the
frontal horns of the lateral ventricles.
-- Up to 50% of patients may have schizencephaly. Others include
dysgenesis of the corpus callosum, olfactory, aplasia, gray matter,
heterotopia, and cerebellar dysplasia.
-- Septo-optic dysplasia is often considered in the spectrum of
holoprosencephaly as representing the most minor form of
Abnormal T1 hypointensities are noted in the left temporal tip region
which demonstrate no significant enhancement on the post-contrast
Abnormal T2 yhperintensity lesion in the left temporal lobe with mild
enhancement on the coronal image.
History: 3 year-old girl with seizures.
Diagnosis: Dysembryoplastic neuroepithelial tumor (DNET)
with nodullar oligodendroglial hypercellularity and focal
ACR Code: 1348.3638
-- An uncommon, slow-growing superficial hemispheric
lesion found mainly in young adults.
-- Due to the slow growth, the cortical location (usually in
the temporal lobe) and the frequent presence of cysts, skull
remodelling with erosion of the inner and middle table is
-- The most common clinical presentation is partial complex
Pre- and post-contrast enhanced head CT images demonstrate
hypodensity lesion in the right middle cranial fossa. No apparent
enhancement is seen.
FLAIR and T1 weighted ( pre- and post-contrast) images of the
brain demonstrate ill-defined large T2 hyperintensity and T1
hypointensity lesion in the right temporal lobe without significant
enhancement on post contrast image (coronal image).
History: 4 year-old boy with partial complex seizures.
ACR Code: 1348.3638
1. Young patients with intractable seizures – almost always
2. Well-circumscribed supratentorial cortical lesions
a. Temporal or frontal lobes most common sites
b. Multinodular architecture (mucinous or gelatinous cysts)
with glioneuronal elements and foci of cortical dysplasia
is also a common finding
3. Benign, nonaggressive
DNET Imaging Findings:
1. Isointense on T1WI, hyperintense on T2WI (often
"bubbly" appearance). Usually don't enhance (20% do).
2. Remodelling of overlying calvarium common (45%).
3. Calcification in 20-25%, gyral thickening/dysplasia.
4. Differential diagnosis:
T1 images show bilateral infiltration of retroconal fat.
Abnormal T2 hyperintensity signals in pons and cerebellum
Post ccontrast images show intense enhancement.
History: 46 year-old male with gait disturbance.
Diagnosis: Non-Langerhans cell histiocytosis (Erdheim-Chester
ACR Code: 158.389
It is a rare histiocytic disorder of adults characterized by an
infiltrate of lipid-laden macrophages, multinucleated giant cells,
inflammatory infiltrate of lymphocytes and histiocytes, that can
involve many organs.
The central nervous system involvement of the hypothalamic /
pituitary axis can lead to diabetes insipidus, intra-&-extra axial
cerebral infiltration, retro-orbital fat infiltration.
They demonstrate as T2 hyperintensity signals which enhance
after Gd contrast administration. There is no significant mass
The most common neurologic manifestation is central diabetes
insipidus and gait disturbance.
Ring enhancing right frontal lobe mass with adjacent parenchymal
edema and associated mass effect.
History: 38 year-old male with seizures.
Diagnosis: Pathology findings indicate that the lesion fulfills
criteria for glioblastoma multiforme. It is astrocytic, mitotically
active, and has exuberant vascular proliferation. Also present
are focal eosinophilic granular bodies as are common in
pleomorphic xanthroastrocytoma (PXA). While the lesion is
thus unequivocally malignant, it is possible that is arose in a
ACR Code: 1318.3634
History: 42 year-old female with sudden onset of headache
Diagnosis: Nonaneurysmal Perimesencephalic Bleed
ACR Code: 152 .729
-- The most common cause of any form of subarachnoid
hemorrhage is trauma. In the case of spontaneous subarachnoid
hemorrhage, 95% of the cases are a result of a ruptured
-- A small percentage of subarachnoid hemorrhages have no
aneurysm found on angiohraphy. They occur spontaneously, and
are usually localized to the perimesencephalic cisterns.
-- The usual outcome for this type of hemorrhage is excellent.
This type of bleed is thought to be caused by a ruptured vein or
Multiple non-contrast head CT images show the supratentorial space is mostly filled
by fluid. Only a small amount of brain tissue is present in the occipital regions,
cerebellum hemsphere, as well as the inferior frontal region.
Only the basal ganglia and inferior frontal lobes are seen. The falx cerebri is
present both posteriorly and anteriorly.
Similar finding are seen on the transcranial ultrasound images.
-- Hydranencephaly is a rare condition in which the brain’s
cerebral hemispheres are absent and replaced by sacs filled with
-- The disorder is caused by an in utero event, most likely either
ischemia or infection. Hydranencephaly can be caused in
experimental animals by tying off both carotid arteries in the first
half of the second trimester.
-- Hydranencephaly is considered to be an extreme form of
porencephaly (a rare disorder characterized by a cyst or cavity in
the cerebral hemispheres).
Non-contrast head CT images show areas of hypodensities involving the bilateral
basal ganglia, right greater than left, as well as the right medial occipital lobe in
the PCA distribution.
History: 54 year-old male with visual change and dizziness.
Diagnosis: Basilar tip thrombosis at the level above SCA causing
bilateral PCA distribution infarction. However, the left PCA
territory is spared due to a fetal poterior communication artery on
the left side. The findings were confirmed by angiography.
ACR Code: 1753.72145
Pre- and post-contrast T1 and T2 weighted images of the brain
demonstrate a complex cystic mass lesion arising from the
lateral wall of the right lateral ventricle with mild post-contrast
History: 42 year-old male with recurrent headache.
Diagnosis: Central neurocytoma.
ACR Code: 1613.3619
-- The central neurocytoma arises from neuronal precursor elements
rather than from glial cells. Most patients are young adults and can
present with symptoms of ventricular obstruction.
-- It usually appears as a well-defined, lobulated intraventricular
mass growing near the foramen of Monro or septum pellucidum.
-- Enhancement is typically mild to moderate and calcifications and
cystic changes are common. Uncommonly, there have been cases of
more aggressive tumor with dissemination.
T1 weighted axial images with and without contrast through the
internal auditory canals demonstrating bilateral 8th nerve
masses with extension into the porous acousticus of the internal
auditory canal bilaterally.
History: 21 year-old male with NF-2 presented with hearing
Diagnosis: 8th nerve Shawnnoma, bilateral.
ACR Code: 154.3641
-- Bilateral acoustic neuromas are a common finding in patients
with neurofibromatosis Type II (NF-2). Other intracranial
abnormalities which are associated with NF-2 include meningiomas
as well as ependymomas and occasionally neuromas involving the
other cranial nerves.
-- The imaging characteristics of acoustic neuromas may be
variable, but they generally present as focal enlargement of the 8th
cranial nerve, often with extension into the porous acousticus of the
internal auditory canal. The lesions most characteristically
demonstrate diffuse and homogeneous enhancement on post
Gadolinium enhanced scans.
Axial noncontrast head CT shows hyperdense material in the
basal cisterns and sylvian fissures, consistent with
AP right common carotid arteriogram shows a rounded contrast
collection in the region of the anterior communicating artery,
consistent with aneurysm.
History: 42 year-old female with sudden onset of severe
Diagnosis: Anterior communicating artery aneurysm.
ACR Code: 1731.7368
-- ACOM aneurysms are among the most common,
representing approximately 1/3 of intracranial aneurysms. 15-
20% of pts will have multiple aneurysms.
-- Large ACOM aneurysms may present with an optic chiasmal
syndrome (bitemporal hemianopsia).
-- Although any size aneurysm may rupture, those measuring
greater than 3-5 mm are at higher risk.
-- Complications include communicating hydrocephalus,
rebleeding (20%), vasospasm (>7d) +/- infarct. 1/3 of pts die
immediately, 1/3 have long term deficit, and 1/3 have near