【Image knowledge】Ten typical neuroimaging signs

Target Signs:

CT scan of the brain with central punctate calcifications or punctate enhancement ring-shaped lesions in the brain, called "target signs"
.
The target is the presentation of mature tuberculous globulbs in the brain on contrast-enhanced CT, with central punctate calcifications, which are characteristic
.
Histologically, the annular strengthening zone corresponds to the fibrocapsule containing inflammatory cells, the unstrengthened zone corresponds to caseous necrosis, and the mechanism of central punctate strengthening is unknown
.

Mt.
Fuji Sign:

After trauma, a large amount of gas accumulation in the skull is often on the top of the frontotemporal gland, especially the frontal part, and in severe cases, a large amount of gas accumulates in both frontal parts, which is exactly like a mountain crest on the CT scan cross-sectional view and presents the "Fuji Sign"
.

Cross signs:

More common in olivepontine cerebellar atrophy (OPCA).

On the T2 weighted image, the cross-shaped signal shadow of the pons, Westerners like to bake a kind of bun with criss-shaped cream on Easter, such a small bun is very similar to the high-signal cross shape formed by the pons on the axial T2 phase! Therefore, this imaging sign of olive pontine cerebellar atrophy (OPCA) is called the "cross bread sign"! Mechanism of crosses: the pontine nucleus and its fibrosis that reaches the cerebellum through the cerebellar mid-foot, while the fibers and pyramidal tracts emitted by the dentate nucleus that make up the upper cerebellar foot are not damaged
.
Degeneration of transverse pontamino fibers and cerebellar midfoot and glial hyperplasia increase their water volume, forming a T2-weighted cross-shaped hypersignal
of MRI like a pontine.
The crucifixion was thought to be a characteristic change
of OPCA.
Similar signs have recently been reported not only in OPCA, but also in the other two types of multiple system atrophy (MSA): striatum nigra degeneration (SND), and Shy-Drage syndrome
.

Hummingbird signs:

Olive, pons, and cerebellum atrophy, and under the background of the enlarged interfoot pool and cross pool, the MRI sagittal position changes in hummingbird beak
.
Olive pontine cerebellar atrophy is a neurodegenerative disease characterized by atrophy of the pons, cerebellar midfoot, and cerebellar hemispheres, and is a more common type
of inherited ataxia.
The cause is unknown
.
The main pathological manifestations are: severe atrophy of the cerebellar hemisphere, ventral pons, and the olive nucleus oblongata, and the red nucleus, substantia nigra, basal ganglia, cerebral cortex and anterior horn of the spinal cord are not affected
.
The first symptoms are progressive ataxia, both lower extremity weakness is the most common, and eye movement disorders are common
.
The main signs of cranial MRI: (1) The shape of the brainstem becomes thinner, especially the small anteroposterior diameter of the pons; (2) The volume of the cerebellum becomes smaller, the cerebellar sulcus fissure widens and deepens, and the hemispheric lobules become thinner and straighter; (3) The brain cistern and ventricle are enlarged, especially the widening of the anterior bridge pool
.

Tiger's Eye Sign:

Hallervorden-Spatz disease (HSD) is also known as globus pallidus.

or pantothenate kinase-associated neurodegeneration is a rare neurodegenerative disease whose clinical manifestations are dominated by extrapyramidal systems, and the bilateral globus pallidus-symmetric high-intensity "tiger's eye sign" weighted by head MRI T2 is the most characteristic manifestation
of the disease.
The gradient echo sequence of MRI is a very sensitive test
for diagnosing neurodegenerative lesions as well as the distribution of iron deposits in the skull.
Although normal people can also have iron deposition in the brain, abnormal, age-inconsistent iron deposition is a feature of HSD, bilateral globus pallidus, substantia nigra symmetric iron-containing pigment deposition is the standard for pathological diagnosis of this disease, head MRI T2 weighting shows bilateral globus pallida symmetric high-intensity "tiger's eye sign" is the most characteristic manifestation
of this disease.

Molar signs:

The cerebellar vermis is not developed or underdeveloped
.
Joubert's syndrome is a rare congenital developmental malformation of the brain, an autosomal recessive genetic disorder, which is mainly characterized by abnormal "midline fissure"
due to underdevelopment or underdevelopment of the cerebellar vermis.
CT and MRI show characteristic bilateral cerebellar interhemispheric "midline signs", cranial to caudal "bat wing" and "triangular" fourth ventricles and midbrain level "molars signs"
, respectively.
The basis of the formation of molars: the upward displacement of the fourth ventricle, hypoplasia of the cerebellar vermis, and the thickening of the upper feet of the bilateral cerebellum, forming molars on cross-sectional images
.

Funnel sign:

Vacuolar sellar CT scan fills the sella with low-density cerebrospinal fluid; The flattened pituitary is crescent-shaped, located posterior inferior to the fossa of the sellar or disappears
.
MRI can show that the pituitary tissue is compressed and flattened, clinging to the bottom of the saddle, the saddle is filled with dripping material, and the saddle floor is significantly subsident, forming a characteristic "funnel sign"
.

Jellyfish head sign:

Also known as sea snake head sign, cerebral vein malformation
.
(brain developmental venous abnormalities) abnormally dilated medullary veins drain into 1~2 thick drainage veins, forming a "sea snake head" sign, not accompanied by blood supply arteries and direct arteriovenous short circuit
.

Salt and pepper signs:

It refers to the mixed signal of the skull base tumor, which is seen in the head and neck paragangliocytoma, which is a characteristic manifestation in MRI of paragangliocytoma, mainly composed of the high signal of slow blood flow in the tumor and the low signal of empty blood vessel flow, indicating that the blood supply of the tumor is abundant
.

New Moon Sign:

CT or MR scan of the brain usually shows a "crescent-shaped" mass under the inner plate of the skull, which is a common characteristic sign
of subdural hematoma.