Neuro Increase Signal T1 Lesion

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Cholesteoma granuloma
-most commonly occur within the petrous apex but occasionally arise in the mastoid segment, middle
ear, and orbitofrontal region
- smooth, well-defined, homogeneous masses that display high signal intensity at T1-weighted imaging
-high T1 signal of these lesions is unaffected by fat suppression techniques
-Cholesterol granulomas are also often hyperintense at T2-weighted imaging
and may display a hypointense rim secondary to
hemosiderin deposition

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Cockayne syndrome
-autosomal recessive defect in DNA repair that is characterized clinically
by premature aging, encephalopathy, microcephaly, deafness, and photosensitivity
-cerebral atrophy, white
matter hypomyelination, and extensive calcifications within but not limited to the bilateral lentiform and dentate nuclei
-MR spectra show the presence
of lactate and decreased levels of choline and
N-acetylaspartate
-calcifications may exhibit high signal intensity at T1-weighted
imaging and low signal intensity at T2-weighted imaging

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Cortical Laminar necrosis
-sequela of a global
hypoxic ischemic event or, less commonly, an
effect of immunosuppressive therapy or chemotherapy
-third layer of the cortex is particularly susceptible to depletion of oxygen and
glucose
-: High-signal
intensity cortical lesions appear on T1-weighted
images about 2 weeks after the inciting event and
become increasingly conspicuous at 1–2 months
after the event, along with maximum contrast enhancement
-T1 signal hyperintensity
usually fades after 2 years, whereas parenchymal
atrophy progresses

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Craniopharyngioma
-benign neoplasms derived from epithelial rests in the Rathke pouch
-tend to be solid and occur in adults, whereas the
adamantinomatous variety tends to be cystic and
occurs in children
-most craniopharyngiomas are located in the suprasellar region, about half demonstrate an intrasellar component as well
-d 90% of craniopharyngiomas
contain calcifications that are visible at CT and
cystic components that sometimes show signal
hyperintensity on T1-weighted images
-cystic portions of
craniopharyngiomas also frequently display T2 hyperintensity and rimlike enhancement on contrastenhanced T1-weighted images

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ECTOPIC POSTERIOR PITUITARY
-rare congenital
malformation of the hypothalamus that is associated with hypoplasia or absence of the pituitary
stalk and resultant dwarfism due to growth hormone deficiency
-ectopic posterior
pituitary lobe is most commonly located along the median eminence in the floor of the third ventricle
-ectopic posterior pituitary
gland also might result from traumatic or surgical
transection of the pituitary stalk
-Signal
hyperintensity in the posterior aspect of the pituitary gland on T1-weighted images is related to
the paramagnetic effect of the vasopressin–neurophysin II–copeptin complex

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Hepatic encephalopathy
-bilateral regions of signal hyperintensity in the lentiform nucleus and substantia
nigra on T1-weighted images
-related to the accumulation
of manganese in patients with hepatic encephalopathy and may be encountered also in welders and recipients of hyperalimentation therapy
-focal areas of signal hyperintensity in
subcortical white matter on T2-weighted images,
and elevated glutamine and glutamate levels at
MR spectroscopy that are probably related to ammonia toxicity
-potentially reversible with liver transplantation

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NEUROFIBROMATOSIS TYPE 1
-autosomal dominant disorder of the neurofibromin gene on chromosome 17
-wide variety of intracranial
manifestations, including hypothalamic–optic
nerve and brainstem pilocytic astrocytomas;
neurofibromas; neurofibrosarcomas; plexiform
neurofibromas; hydrocephalus; arachnoid cysts;
cerebrovascular occlusions; nontumorous highsignal-intensity foci or unidentified bright objects
that occur predominantly in the basal ganglia and
posterior fossa on T2-weighted images; and highsignal-intensity lesions, distinct from unidentified
bright objects, that most commonly appear in the
basal ganglia on T1-weighted images
-T1-hyperintense basal ganglia lesions occur
in approximately 20% of patients with type 1 neurofibromatosis (57,58) and predominantly involve
the globus pallidus and internal capsules bilaterally
and symmetrically
-basal ganglia lesions
in type 1 neurofibromatosis do not exhibit mass
effect, surrounding edema, or enhancement.

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RATHKE CLEFT CYST
-occasionally cause headaches,
visual disturbances, and diabetes insipidus
-half of Rathke cleft cysts show hyperintense signal
at T1-weighted imaging
-hyperintense at T2-weighted
imaging
-Small intracystic nodules with high signal
intensity at T1-weighted imaging and low signal
intensity at T2-weighted imaging are present in
approximately 45% of cases
-presence of peripheral enhancement and an increased
risk of recurrence after surgical resection

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WILSON DISEASE
-rare autosomal recessive condition caused by mutations in the ATP7B gene
with resultant abnormal copper metabolism and
accumulation
-Patients may present with
dysarthria, dystonia, tremor, choreoathetosis,
liver failure, and classic Kayser-Fleischer rings
at ophthalmologic examination
-most commonly
found in the bilateral basal ganglia and ventrolateral thalami
-Regression of the signal abnormality at T1-weighted MR imaging correlates
with response to treatment
-Involvement of the striatum at MR
imaging manifests with pseudoparkinsonian
signs, dentatothalamic tract involvement manifests with cerebellar signs, pontocerebellar tract
involvement correlates with pseudoparkinsonian
signs, and globus pallidus involvment is associated with portosystemic shunting secondary to
cirrhosis

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AMYLOID ANGIOPATHY
-disorder of
b-amyloid deposition in cortical, subcortical,
and leptomeningeal vessels
-responsible for only about 2% of all
intracranial hemorrhages, it is relatively common among the elderly
-petechial
microhemorrhages or macrohemorrhages with irregular borders in a lobar distribution in cortical
and subcortical regions are characteristic findings
of amyloid angiopathy
-Intraparenchymal
hemorrhages at various stages of evolution, as well
as subarachnoid, subdural, and intraventricular
hemorrhages, may be seen at imaging

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CEREBRAL VENOUS THROMBOSIS
-most commonly manifests with
a headache
-computed tomography (CT) is the
presence of a hyperattenuating clot, although this
feature is apparent in only about 20% of cases
-e “empty delta” sign, a filling defect
at contrast-enhanced CT or CT venography,
is present in less than 30% of cases
-subacute thrombus
often has high signal intensity on T1-weighted
images, signal intensity on T2 weighted images is more variable but is also usually high
-MR venography is effective for depicting the extent of venous occlusion and collateral
vessel formation

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CEREBRAL VENOUS THROMBOSIS

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COLLOID CYST
-headache is the most common clinical manifestation in symptomatic patients
-atonic seizures, nausea, vomiting,
diplopia, transient loss of consciousness, and
(rarely) sudden death
-About two-thirds of colloid cysts show high signal intensity at T1-weighted MR imaging, and
most exhibit low signal intensity at T2-weighted imaging
-Colloid cysts that
show low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging have a tendency to enlarge rapidly

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PERICALLOSAL LIPOMA
-

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RUPTURED DERMOID CYST
-rare complication that can cause severe chemical meningitis
and sensory or motor hemisyndrome
-dermoid cysts typically show high
signal intensity on T1-weighted images, variable
signal intensity on T2-weighted images, and lack
of enhancement on contrast-enhanced images
-MR spectroscopy discloses mobile lipid
peaks at 0.9 and 1.3 ppm
-e lesions are usually well-defined, nonenhancing masses with fat attenuation at CT