Thursday, 21 September 2017

Giant Tumefactive Perivascular Spaces MRI

Clinical Details: headache.
FLAIR
T1W
T2W
T2*GRE
T1 PC
MRI brain with Contrast

MRI study of brain with contrast shows a well defined, multilocular cystic lesion isointense to CSF, non-enhancing on post contrast involving left thalamus, adjacent mesencephalic mid brain. An associated mild mass effect causing third ventricle compression however no obvious obstructive hydrocephalus. No obvious low signal intensity haemosiderin staining on GRE. No obvious adjacent perilesional oedema on FLAIR.

Imaging findings suggestive of giant Tumefactive Peri vascular space – a benign non-tumoural cyst.
Suggested follow-up imaging for mass effect.

Giant Tumefactive Perivascular Spaces

Perivascular spaces (PVSs) are pial-lined, interstitial fluid-filled structures that accompany penetrating arteries, also known as Virchow-Robin spaces when enlarged, they may cause mass effect and can be mistaken for various ominous pathologic processes.
Often appear as clusters of variably sized cysts that are isointense to CSF on all pulse sequences and do not enhance, Gaint Tumefactive VR spaces assuming bizarre configurations with striking mass effect should not be mistaken for neoplasm.
They are most common in the mesencephalo thalamic region and may cause hydrocephalus.

Reference: Giant Tumefactive Perivascular Spaces Karen L. Salzman, Anne G. Osborn, Paul House, J. Randy Jinkins, Adam Ditchfield, James A. Cooper and Roy O. Weller
American Journal of Neuroradiology February 2005, 26 (2) 298-305



Japanese encephalitis MRI

Clinical Details : fever with seizures, loss of consciousness.
Clinically no history of poisoning or primarily metabolic derangement.




This MRI study of brain FLAIR and Diffusion shows abnormal T2 hyperintensity with marked parenchymal swelling, bilateral and Symmetrically involving thalami, Pons, bilateral cerebellar hemisphere with restricted diffusion. Confluent T2 hyperintensity Bilateral Symmetrically involving fronto parietal Peri ventricular white matter.
Oedematous thalami causing Third ventricle compression leading to mild dilatation of lateral ventricles. Diffuse cerebral oedema.
Normal MR venography of brain.

Imaging wise differential diagnosis:
Viral encephalitis Japanese encephalitis
Toxic/Metabolic leukoencephalopathy.

Japanese encephalitis

Causative agent is Japanese encephalitis virus , a single-stranded RNA flavivirus.
Domestic pigs and wild birds are reservoirs for the virus, spreads by mosquitoes. Disease is prevalent in India, South East Asia.

Clinical presentation is usually rigors, fevers and headache.
Neck rigidity, cachexia, hemiparesis and convulsions as signs of meningitis as disease progresses.

Bilateral thalamic involvement is classical as hypodensities on CT and T2 hyperintensities on MRI with restricted diffusion, marked a focal parenchymal swelling. Associated midbrain, pons, cerebellum, basal ganglia, cerebral cortex and spinal cord involvement is well known. Imaging after 3-4 days of the onset may reveal haemorrhage giving rise to low signal intensity haemosiderin staining on GRE.

Treatment is only supportive with higher mortality rate. Vaccination may be preventive in endemic areas.

Differential diagnosis
Other infectious causes that can cause a similar imaging pattern are Murray Valley encephalitis, West Nile fever, eastern equine encephalitis, herpes simplex encephalitis.
However in Herpes which is promptly treatable with antivirus treatment, the medial temporal lobe involvement is classical with uncommon thalamic involvement.
Bilateral thalamic haemorrhage in Japanese encephalitis is often confused with deep cerebral vein thrombosis. So it is important to run MR venography to demonstrate normal straight sinus.

Friday, 18 August 2017

Fukuyama Congenital Muscular Dystrophy MRI


Clinically:
Brachycephaly.
Hypotelorism, convergent squint
Delayed milestones.



MRI study of brain shows:
Bilateral symmetric frontal lobar Poly micro gyria.
Diffuse cerebral cortical atrophy with mild dilatation of lateral ventricles.
Bilateral Cerebral Periventricular as well as sub cortical white matter show symmetric confluent T2 hyperintensity with white matter paucity suggestive of hypo myelination.
Marked atrophy of Brainstem particularly Pons, hypo plasia with a typical midline cleft.
Bilateral cerebellar hemispheres show multiple T2 hyperintense small cysts with micro folia attributed to an associated cerebellar dysplasia, Polymicrogyria with mild hypo plasia of cerebellar vermis. Postero fossa normal sized.
Bilateral Basal ganglia and thalami spared.

Imaging findings are typical of Fukuyama Congenital Muscular Dystrophy.

Reference : American Society of Neuroradiology : Fukuyama Congenital Muscular Dystrophy

Fukuyama Congenital Muscular Dystrophy

Heterogeneous group of inherited disorders characterized by myopathy and hypotonia at birth. 
Rarely occurs outside the Japanese population.
Autosomal recessive inheritance; gene locus identified on chromosome 9.
The disease onset typically occurs in early infancy. Initial symptoms may include a poor suck, weak cry, floppiness, symmetrical generalised muscle weakness and hypotonia. Facial myopathy may also be seen and increases with age. Developmental and speech delay occur in all individual with FCMD. Other symptoms include seizures, clinical features related to cardiomyopathy, and cardiac failure. Survival beyond 20 years is uncommon, and death usually occurs following respiratory complications.
The diagnosis of FCMD is usually established by clinical features, characteristic findings on neuroimaging, and serum CK concentration. Molecular genetic testing, when available, is usually performed to confirm the diagnosis.
Key Diagnostic Features are cerebral and cerebellar polymicrogyria with accompanying cysts, and mild ventricular dilatation. Uncommonly, agenesis of septum pellucidum can be seen.
Rx: Supportive therapy.

Sunday, 15 January 2017

Orbital Calcifications

Case: 1
This is a 50-year-old man who underwent CT for headache.
Calcification of the trochlea
Calcification of the trochlea
CT demonstrates punctuate calcification in the anterior, medial and superior corner of the orbit.

Calcification of the Trochlea

Clinical presentation: Incidental finding.
Imaging findings: CT demonstrates punctuate calcification in the anterior, medial and superior corner of the orbit. The location is important not to be mistaken as a high-density foreign body.
Unilateral / bilateral symmetric.

The trochlea is a cartilaginous structure with a synoviumlined sheath that permits unimpeded movement of the superior oblique muscle. The tendon of the superior oblique muscle passes through the trochlea before it inserts along the supero-lateral portion of the globe. Calcification of the trochlea is often seen in elderly patients (25-30% in persons over 50 years old) and considered as degenerative change without clinical significance.
However, if the patient is younger than 40 years of age, there is a statistically significant correlation with diabetes and these findings should prompt an endocrine evaluation.
Other less common causes of trochlear calcification are Brown’s syndrome, traumatic and postsurgical changes.

Case 2:
This is a 16-year-old adolescent who presented with slowly progressive vision loss in the left eye.
Choroidal osteoma
CT demonstrates a plaque-like calcification in the posterior pole of the affected eye.

Choroidal Osteoma

Clinical presentation: new onset of blurry, distorted vision.
Imaging findings: CT demonstrates a plaque-like calcification in the posterior pole of the affected eye.

Choroidal osteomas are rare, benign, ossifying, choroidal tumors of unknown etiology. Histopathologic evaluation reveals mature bone with marrow space containing loose fibrovascular tissue. They occur predominantly in young females (90%) without a history of systemic or ocular disease, and are usually unilateral (75%). On ophthalmologic examination, they appear as yellow-white to orange-red plaques and are generally located in the macula or juxtapapillary region around the optic disc extending toward the macula. Variability in color occurs secondary to thinning, depigmentation, and hyperplasia of the overlaying retinal pigment epithelium.
They are typically oval in shape with well-defined scalloped margins. They may display progressive growth patterns, although regression in size has also been reported.

Complications include choroidal neovascularization (CNV), which can result in vision loss and subretinal hemorrhage. Retinal detachment is also common.
Ultrasound and CT are of particular value in diagnosing choroidal osteoma.
With B-mode sonography, choroidal osteoma shows increased echogenicity posteriorly within
the globe, with posterior acoustic shadowing, creating the “pseudo-optic nerve appearance.” On CT, choroidal osteomas are flat calcified lesions, less than 2 mm in thickness, within the posterior pole of the globe. They are typically located in the juxtapapillary region, and typically do not involve the center of the optic disc, which aids in differentiation from optic drusen.
Given their benign nature, choroidal osteomas are typically followed clinically. Identification of complications, particularly choroidal neovascularization, warrants treatment
given the risk of vision loss.
DD:
• Optic drusen.
• Choroidal metastases:
• Choroidal hemangioma.
• Hyaline plaque.

Case 3:
This is a 65-year-old man who underwent CT for headache.
Hyaline plaque
CT demonstrates punctuate calcifications on the surface of the globe at the 3 and 9 o’clock location

Scleral Calcification: Hyaline Plaque

Clinical presentation : Incidental finding.
Imaging findings: CT demonstrates punctuate calcifications on the surface of the globe at the 3 and 9 o’clock location and are usually bilateral. Common areas of degenerative hyaline plaque formation are at the insertions of the medial and lateral rectus muscles. It is thought that these calcific deposits are of no clinical significance. These patients are usually older than 80 years of age; however, this condition can be seen earlier in patients with a history of cataract surgery or other infectious or inflammatory conditions.
On CT, there is a clearly defined focal high-density lesion at the insertions of the medial and lateral rectus muscle, again typically at 3 and 9 o’clock locations. These lesions
are difficult to visualize on MRI, although a signal-void can occasionally be identified.
Metallic or glass foreign bodies can show a similar appearance. Therefore, careful evaluation of the location of high-density lesions is critical. Hyaline plaques are seen in the typical surface locations in elderly patients, and should be easily distinguished from high-density foreign bodies.

DD:
Foreign body.
Optic drusen seen in the surface of the optic disc, which become calcified with advancing
age. However, drusen can be seen in relatively young patients.
Choroidal osteoma is a benign, ossifying, choroidal tumor of unknown etiology. It occurs predominantly in young females with no history of systemic or ocular disease, and usually unilateral.

Case 4: 
This is a 68-year-old man who underwent CT for headache.
Optic drusen

CT demonstrates a punctuate calcification at the optic disc.

Drusen

Clinical presentation : Incidental finding.
Imaging findings: CT demonstrates a punctuate calcification at the optic disc.

Drusen is caused by the accumulation of mucopolysaccharides and proteinaceous material on the surface of the optic disc, which can become calcified with advancing age.
There is an inherited form with an autosomal trait with irregular penetrate.

Drusens are commonly asymptomatic and incidentally found on CT performed for other reasons. These lesions can cause visual field defects and rarely can also lead to deficits in central acuity. Approximately 75% of drusen are bilateral. They are usually seen in elderly patients, and are rare in children. They are also believed to cause headaches. The diagnosis of drusen is simplified when these
Lesions lie on the surface of the optic disk, where they can be easily detected on fundoscopic examination. When drusen lie deep within the tissue of the optic nerve, however, the typical fundoscopic appearance may not be evident. When these small lesions develop within the nerve tissue, they can lead to elevation of the disc, which can be diagnosed as papilledema
(pseudopapilledema). Under these circumstances, CT or MRI can be performed to look for conditions that may cause elevated intracranial pressure.

DD:
• Choroidal osteoma: Choroidal osteoma is a benign, ossifying, choroidal tumor of unknown etiology. It occurs predominantly in young females with no history of systemic or ocular disease, and usually unilateral.
• Choroidal hemangioma: Choroidal hemangioma is a benign vascular tumor with phebolith.
• Choroidal metastases: Metastatic choroidal tumors are not rare, although they are not very often appreciated clinically. Most common primary sites are breasts and lungs.
• Hyaline plaque: This is degenerative change and seen in elderly populations, usually more than 80 years old. Focal calcification is seen at the insertion of medial and lateral rectus muscles.

Case 5: 
30 y o male with history of firework trauma, foreign body. Now reduced vision.
Foreign body
CT demonstrates hyper dense foreign body in left orbital pre septal space.

Imaging findings: Most typical or important is nothing typical.  Often unilateral , can be bilateral but never symmetric.
Clinical presentation : Often Symptomatic. History of trauma is most often present followed by reduced vision with or without pain.

Friday, 6 January 2017

Artifact from Eye Makeup

This is a 45-year-old woman who underwent MRI for headache.
Axial MR image demonstrates signal loss and image distortion of the anterior portions
of the eyes. Image distortion is more significant with gradient echo
(field echo) imaging compared with other sequences. 
 
Eye makeup, both mascara and tattoo eyeliner can cause image distortion and signal loss associated with the use of iron oxide or other metal-based pigments. Therefore, the patient should be advised to remove eye makeups before MR exam, if possible, particularly when indicated to evaluate for abnormalities in the brain and face.

Slight “tingling” and sensation of “burning” have been reported in subjects who wear permanent cosmetics, however, the frequency and severity of soft tissue reactions or other problems related to MRI and permanent cosmetics is unknown. Therefore, permanent cosmetics should not prevent patients from undergoing MRI. Decorative tattoo has higher chance to cause worse complication compared to cosmetic tattoo. Radiologist or technician should be informed that the patient wears permanent makeup or tattoos before the exam and possible complication and artefact should be discussed with patients.

Sunday, 1 January 2017

Spinal Epidural lesion MRI

Clinically lower limb weakness, left upper limb radiculopathy.
Here is MRI cervical spine with contrast
SAG T1
SAG T2
SAG STIR
COR STIR
AXIAL T2
SAG PC T1
SAG PC FAT SAT T1
AXIAL PC T1
MRI Report

MR imaging of cervical spine with contrast reveals:
An ~ 20x9mm focal anterior epidural lobulated mixed signal intensity lesion on left side of cord at C6-7 causing moderate compression over cord, corresponding exiting C7 nerve root not seen separately in neural foramen. Lesion has central low signal stripe on T2w images and rest of the lesion is iso intense on T2 , iso to hyper intense signal on T1 w images, moderate to avid enhancement on post contrast.
DDs given were : Spinal epidural Hematoma, Neurofibiroma, Lymphoma.

video

Operative findings and Histopathology Report

Gross appearance: Specimen consist of dull gray brown tissue, dilated vein.
Microscopy: single collapsed undulating vascular channel devoid of any recognizable lining endothelia and smooth muscle component. Collapsed lumen show RBCs.
No e/o malignancy.

Final diagnosis : Venous Ectasia.



Spinal Epidural Venous Ectasia /Varix

Epidural Ectasia / Venous varix is an uncommon entity originally reported in the literature by Cohen in 1941. The incidence has been reported to be .07% to 1.3%.

The vertebral venous plexus consists of a retrovertebral plexus framed by paired anterior internal vertebral veins which are oriented craniocaudally and connected to the ascending  veins, these veins are located laterally on the vertebral bodies, via the supra- and infrapedicular veins. The plexus veins course close to the neural foramina and exiting nerve roots. The segmental veins connect the ascending lumbar veins to the inferior vena cava. This system of veins is valveless, thereby permitting retrograde flow and vascular dilation. The abnormal flow and dilation may occur in cases of caval compression, which may be seen with increased abdominal pressure.This has been postulated as an etiologic factor in the development of epidural varices.
Clinically, such varix in lumbar region, patients often present with radicular symptoms, such as pain, numbness, or parasthesias of the legs. An increase in intra-abdominal pressure with compression of the inferior vena cava and resulting venous engorgement and nerve root compression is suggested as cause. This scenario can be seen in pregnancy, obesity, and the valsalva maneuver.
such varix in cervical region is further rare and in our case this was causing cord compression.
Such venous dilation is also associated with a history of trauma and concurrent herniated disc. The hypothesis that the development of the varix may be secondary to compression of vertebral veins by the adjacent disc, thereby leading to dilation and thrombosis.
Imaging findings of this entity are often non-specific. On CT, the lesion appears as a soft-tissue density in the epidural space, often extending into the neural foramen. Myelography may disclose a filling defect in the contrast column at the disc space level. On MRI, the varix appears as a dilated with variable signal, T1 hypo intense to iso intense. May be T1 bright due to sub acute stage thrombus in the varix. Fine serpiginous flow void may be seen in the epidural space as in our case hypointense on T1- and T2-weighted images. The dilated vein will show enhancement following intravenous contrast administration.

As the appearance is non specific, the differential diagnosis may include epidural hematoma or abscess, herniated disc, or some times neurogenic tumor with neural foraminal component.
Treatment is surgery with coagulation and resection. Postoperatively, patients often report relief of symptoms. There are no any reports of recurrence of this entity following surgery.

Conclusion
We have presented a case of symptomatic epidural varix. This entity is extremely rare, and a radiologist will likely encounter only a handful of such cases in his or her career. However, the diagnosis should be suggested in the proper clinical setting when an epidural lesion brightens on T2 images and enhances with contrast.

Sunday, 25 December 2016

Amyotrophic Lateral Sclerosis

        MC form of motor neuron disease.
        Progressive, neurodegenerative disorder.
        Upper (hyper reflexia, spasticity) and lower (fasciculation, atrophy) neuronal symptoms
       No autonomic, sensory, or cognitive involvement.

        Male predilection, onset in middle and late adult years.

Selective degeneration of somatic motor neurons of brain stem/spinal cord ( LMN), large pyramidal
neurons of motor cortex (upper motor neurons, UMN), eventual loss of corticospinal tract (CST) fibers.

Best diagnostic clue bilateral hyperintensities along CST extending from corona radiata to brain stem on
T2WI/PD /FLAIR.



Huntington Disease

Findings:
Diffuse cortical atrophy w/caudate nucleus and putamen most severely affected
Atrophy of caudate nucleus results in characteristic enlargement of the frontal horns, which take on a heart-shape configuration.

Huntington disease (HD), Huntington chorea

Autosomal dominant neuro degenerative disease with loss of GABAergic neurons of basal ganglia (BG)

Clinical triad: Early onset dementia, choreoathetosis, and psychosis.

Best diagnostic clue: 
Atrophy of caudate nucleus (Cn), loss of convex surface of caudate head, enlargement of frontal horns of lateral ventricles.

Location
o Primarily striatum (especially Cn, putamen)
o Cerebral cortex, globus pallidus (GP), thalamus
o Substantia nigra (SN), brainstem

CT / MRI
o Cn atrophy is measured on axial images at level of 3rd ventricle
• Intercaudate distance (CC) between most medial aspects of Cn
• CC compared with distance between most lateral aspects of frontal horns (FH)
• CC compared with distance between inner tables (IT) of skull at level of CC measurement
• Increase in CC relative to FH or IT
• Decrease in FH/CC ratio
• Increase in CC/IT ratio (bicaudate ratio): Most specific and sensitive measure for HD

MRS
increase in Lactate concentration in occipital cortex of symptomatic HD, also in BG in some patients
Lactate level correlates with duration of illness
Decrease in N-acetylaspartate/creatine in BG (neuronal loss)
Markedly increased Choline/creatine ratio in BG (gliosis)

Nuclear Medicine Findings
• PET
decrease in FDG uptake in BG before any detectable atrophy
Frontal lobe hypometabolism
• SPECT: Perfusion defects in motor cortex, prefrontal cortex, and BG correlate with clinical disease.

Clinical Issues

• Movement disorder
• Mean age of onset: 35-44 y in adult-onset HD

Pathology
CAG trinucleotide repeat disease affecting HD gene on chromosome 4p16.3
 Polyglutamine expansion =} Huntington accumulates in nucleus and cytoplasm =} cytoplasmic Huntington aggregates in axonal terminals, neuronal loss and gliosis.

Patterns of abnormal brain enhancement

Pachy meningeal Enhancement (Intracranial Hypo tension)

Lepto meningeal  Enhancement 
causes: Menigitis, SAH, Metastases

Gyral Enhancement
       Vascular: re perfusion of ischemic brain, migraine, PRES, seizures
       Inflammatory: meningitis, encephalitis

Nodular Cortical and Subcortical Enhancement
       Hematogenous dissemination of metastatic neoplasms and clot emboli.

Open Ring Enhancement
       Multiple sclerosis (without mass effect)
       Tumefactive demyelination (with mass effect)
       Fluid-secreting neoplasms (with mass effect and occasionally with surrounding vasogenic edema)

Peri ventricular Enhancement
       Primary CNS lymphoma
       Primary glial tumors
       Infectious ependymitis 

Reference : radiographics.rsna.org

NF1


Findings:
Multiple T2 bright lesions in the basal ganglia and dentate nuclei = “NF spots”
Bilateral optic nerve enlargement (Gliomas)