Sunday, 29 August 2021

Leukoencephalopathy, Calcifications and Cysts MRI


Clinically middle age male with history of progressive headache for last 5months.
CT brain shows multiple dense bilateral basal ganglia calcification. 
DDs thought were like Fahrs disease, hypo thyroidism, hypo, pseudo hypo para thyroidism.
However patients thyroid and para thyroid profile was normal and the posterior cranial fossa cyst could not be explained even by Fahrs. With a possibility of a concurrent posterior fossa tumor, patient was referred for MRI brain with contrast.
MRI brain with contrast showed dense calcification in bilateral basal ganglia. The posterior fossa cyst with debris level. No abnormal enhancement along wall of cyst or enhancing eccentric solid nodule depicted on post contrast MRI which ruled out tumor nodule. 
The bilateral symmetric confluent T2 white matter hyper intensity which represents an associated leukoencephalopathy.

Imaging wise primary diagnosis given was LCC. 

Due to mass effect, fourth ventricle compression by the posterior fossa cyst leading to obstructive hydrocephalus, patient underwent posterior fossa craniotomy and excision of posterior fossa cyst was done. Histopathology revealed nonspecific cyst without any tumor cells keeping with MRI diagnosis of LCC. 

LCC or  Labrune syndrome syndrome MRI

Leukoencephalopathy, brain calcifications, and cysts (LCC) also known as Labrune syndrome, an extremely rare with only near  10 cases reported so far in the medical literature.

The condition is caused by homozygous or compound heterozygous mutations in the SNORD118 gene on chromosome 17p13. Clinical presentation varies from spasticity, dystonia, seizures, and cognitive decline.

Etiopathogenesis of LCC is still a matter of debate. Obliterative microangiopathy has been found on histopathological examination as the basic abnormality, the cyst formation is due to necrotic process secondary to obliterative microangiopathy and calcifications is dystrophic in nature. White matter changes result from changes in water content rather than abnormality of myelination.

Another entity which deserves a special mention is cerebro retinal microangiopathy with calcifications and cysts is a distinct genetic disorder due to CTC1 gene problem. Similar leukoencephalopathy, cysts, and calcification have been reported in few cases in association with Coat's disease, described as “Coat's plus. Coat's disease is unilateral retinal telangiectasia with exudation commonly occurring in boys sporadically without systemic features. However, in Coat's plus, there is bilateral retinal telangiectasia with exudation along with systemic features in the form of LCC. 

In my case patient did not have any visual issues so that rules out retinal abnormality and the possibility of cerebro retinal microangiopathy. 

Ears of the lynx sign MRI Brain


Ears of the lynx sign

The ears of the lynx sign refers to an abnormal bilateral symmetric cone-shaped hyperintensity on FLAIR and T2w images at the tip of the frontal horns of lateral ventricles. The abnormality corresponds to the region of forceps minor which resembles the tufts of hair crowning the ears of a lynx. Sagittal T1w images show an associated thin stripe of corpus callosum. 

The sign is typically seen in hereditary spastic paraplegia with thin corpus callosum (HSP-TCC), a form of hereditary spastic paraplegia associated with mutations of the spastic paraparesis gene 11 (SPG11) on chromosome 15. The spatacsin vesicle trafficking associated (SPG11) gene, codes spatacsin. 

The sign may also be seen in SPG15, another of the hereditary spastic paraplegias, which is caused by a mutation in the zinc finger fyve domain-containing protein 26 (ZFYVE26) gene, encoding spastizin. 

This sign has also been described in chronic cases of Marchiafava-Bignami disease.

Isolated Superficial Sylvian Vein Thrombosis MRI


Clinical Details: middle-aged female, altered sensorium after convulsions.


MRI study of brain shows:
Abnormal T2 hyperintensity with marked focal parenchymal swelling due to vasogenic oedema involving left temporal, insular cortex and adjacent opercular parietal white matter. 
Diffusion restriction in corresponding region confined to cortical grey matter of left temporal lobe and adjacent insular cortex on diffusion weighted images. Sub cortical white matter is spared.
 An abnormal leptomeningeal enhancement depicted along left sylvian fissure and in left medial temporal region near cavernous sinus on post contrast MRI. 
Multifocal low signal intensity clustered nodularity demonstrated along left sylvian fissure extending towards cavernous sinus on GRE, which is hyper dense on CT. No abnormal calcification on CT. Normal MR angiography of brain. No obvious aneurysm or high flow vascular malformation on MR angio.
Mass effect, mid brain compression.

Left side Decompressive hemicraniectomy done.
Intraoperative findings revealed thrombosed superficial cortical veins in left sylvian fissure region and at the floor of left middle cranial fossa. 

Final diagnosis: Isolated superficial middle cerebral or Sylvian vein thrombosis.

Superficial middle cerebral vein also known as the Sylvian vein, is one of the superficial cerebral veins. It usually courses along the Sylvian fissure posteroanteriorly and drains numerous small tributaries from the opercular areas around the lateral sulcus. It curves anteriorly around the tip of the temporal lobe and drains into the sphenoparietal sinus or directly into the cavernous sinus. 

Suzuki classification of the superficial Sylvian venous drainage pathways:
1. sphenoparietal type: (54%) drains into the sphenoparietal sinus.
2. emissary type: (12%) courses along the lesser wing of sphenoid, turns inferiorly to reach the floor of the middle cranial fossa, joins the sphenoidal emissary veins, and passes through the floor to reach the pterygoid plexus.
3. cavernous type: (7%) directly drains into the anterior end of the cavernous sinus.
4. superior petrosal type: (2%) runs along the lesser wing and just before reaching the cavernous sinus, turns downward along the anterior inner wall of the middle cranial fossa, then runs along its floor medially to the foramen ovale to join the superior petrosal sinus.
5. basal type: (2%) runs along the lesser wing, turns downward along the anterior wall of the middle cranial fossa, then runs along its floor laterally to the foramen ovale over the petrous pyramid, presumably to join the transverse sinus through the lateral tentorial sinus or superior petrosal sinus.
6. squamosal type: (2%) turns directly backward along the inner aspect of the temporal squama and runs posteriorly to join the transverse sinus or lateral tentorial sinus.

Sunday, 27 December 2020

GCT of tendon sheath




 
GCT of tendon sheath

Synonyms: 
Giant cell tumour of the tendon sheath 
Tenosynovial giant cell tumour
Pigmented villonodular tumour of the tendon sheath (PVNTS)
Localised or focal nodular synovitis.

They are usually seen as localized, single, slow-growing, subcutaneous soft tissue nodules, with or without pain on local examination, very common in hand and wrist, encountered during 3rd to 5th decades with slight female predilection.

On MRI, well defined ovoid lesion with low signal on T1 and T2 images, mild to moderate enhancement on post contrast, may show pressure erosion of adjacent bone, or rarely can invade the bone mimicking an intraosseous lesion on imaging.

Actually they thought to arise from the tendon sheath but unclear whether they represent neoplasms or just reactive masses. Intra articular GCT involving larger joints also very common as in this case. 

Histolopathogically identical to pigmented villonodular synovitis (PVNS), composed of fibroblasts and multinucleated giant cells, foamy histiocytes, and inflammatory cells on a background fibrous matrix.

Being benign local surgical excision usually suffices with local recurrence of nearly in 10-20% of cases requiring more extensive surgery with or without radiotherapy.

Talocalcaneal ganglion cyst



A subtalar ganglion with intraosseous component in the calcaneus.
Ganglion cysts are very common mucin-containing cystic lesions that affect a wide variety of joints of the body, including foot and ankle.

Sunday, 6 December 2020

COVID 19 Cerebritis

Clinically: A known case of COVID 19 positive admitted for fever and breathlessness.

After five days of hospital admission developed sinusitis, headache and started worsening repidly. Subjected for MRI due to sudden onset loss of consciousness and neurological examination revealed new onset ophthalmoplegia. 


MRI shows bilateral geographic shaped patchy T2 hyperintensities involving frontal lobes with diffusion restriction at the floor of anterior cranial fossa. Mild lepto meningeal enhancement on post contrast. 
An associated marked bilateral paranasal sinusitis.

Possibility of COVID 19 Cerebritis, Neuro invasiveness by transnasal route suggested and can be attributed to known Neurotropism of the virus. 

Neurotropism of Covid 19

Neuronal pathway is one of important way of spread of neuropathic viruses like Cov to enter central nervous system. These viruses can migrate with the help of sensory as well as motor nerve endings and have ability of retrograde as well as antegrade spread along the olfactory nervous system due to the unique anatomical organisation of olfactory nerves and olfactory bulb in the nasal cavity and fore brain. As a result, Cov after paranasal sinus infection can enter brain through olfactory tract in early stages of infection rapidly, within seven days of infection as in our case.



Madhura mycosis of foot

 

Sagittal T2w
Sagittal T1w

Sagittal STIR

MRI study of ankle/foot with x-ray correlation shows:

A lobulated abnormal soft tissue measuring approximately 70 mm in length and 40 mm in depth on dorsal aspect of foot encasing extensor tendons with hypo intense signal on T2-weighted images, “dot in a circle” sign on MRI. 

Soft tissue density on x-ray without dystrophic calcification on x-ray. Lytic destruction of adjacent anterior corner of tibia on MRI and x-ray. Associated tibio talar joint effusion. Multifocal ovoid lytic lesion with sclerotic rim on x-ray involving distal end of tibia with fluid signal on MRI. Marginal lytic destruction of distal end of fibula. Circumferential punched-out marginal erosion of neck of talus which is markedly thinned out with an associated marrow oedema on STIR. Multifocal marrow oedema involving tarsal bones, tenosynovitis of extensor as well as plantar tendons.

Multiple ulcers, nodules and discharging sinuses on skin of dorsal aspect of foot when examined clinically.

Imaging diagnosis: Madhura mycosis of foot with osteomyelitis of tibia.

Sunday, 13 September 2020

Hahn cleft or canal MRI lumbar spine

 

A linear low signal running transversely in L1 vertebral body through its whole sagittal diameter without marrow odema on STIR.

It's a "Hahn cleft or canal", a normal anatomical variation of no clinical significance and is secondary to persistent nutrient artery and its canal, should not be mistaken for fracture. 

Friday, 3 July 2020

Corona and Chest Imaging

COVID 19 stands for Corona virus disease 2019.
It’s a highly contagious disease caused by severe acute respiratory syndrome corona virus 2, SARS COV 2, a race of corona virus.
Initial cases were seen in Wuhan of China in late December 2019 with the rapid spread of disease globally and came up as a pandemic affecting more than 10 million people worldwide. 
Non-symptomatic carriers and asymptomatic transmission is a major cause of poor control over the disease.

Disease transmission is primarily human-to-human as of now,  transmitted similarly as the common cold, via contact with droplets of infected individuals during sneezing, coughing or even speaking. 

The suggested incubation period of the disease is approximately five days, almost all developing symptoms typically 14th day after the exposure to the virus. Fortunately, the death rate of the disease is only 2 to 3%. Furthermore, it is speculated that the death rate is much lower than that because asymptomatic or mildly symptomatic cases are not being tested and included in the statistics, apparently showing the high death rate.
It is interesting to mention that 60% of patients affected are male with high predominance between 45 to 60 years of age. Older age is known for increased mortality. Children across the globe relatively found spared by the disease. However, critically ill children under 12 years of age and infants are known as well in certain corners of the world with a shorter incubation period of about two days compared to adults.

Clinical presentation is typically systemic or respiratory. Gastrointestinal or cardiovascular symptoms are very uncommon. Common symptoms in the descending order are fever 85-90%, cough 65-70%, fatigue, shortness of breath, body pain, headache, sore throat, shivering with associated nausea vomiting.
Patients presenting with palpitations, chest tightness, urinary tract infection, diarrhoea are also known.

RT-PCR Swab test 

A positive RT-PCR test needed for a definitive diagnosis of disease.
Its real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test, is highly specific, but with sensitivity reported as low as 60-70%. Thus, false negatives are a real clinical problem so several negative tests might be required to be confident about excluding the disease.
A false-negative rate of 100% on the first day after exposure, dropping to 67% on the fourth day. On the day of symptom onset approximately 4 days after exposure, the false-negative rate remains at 40 %, and it reaches its lowest to 20% at around three days after symptoms during which test has the highest accuracy. After this again the false-negative rate increases reaching 66% on day 21 after exposure. 

Role of CT chest

CT findings were not part of the diagnostic criteria for COVID-19. However, CT findings have been used controversially as a surrogate diagnostic test by few including me being fast and highly sensitive. 
I would like to mention that CT is not recommended for follow-up imaging to assess disease progression. Chest X-ray is considered to be the best for bedside follow-up in this regard. However, chest Xray is much less sensitive than chest CT, so its very common to have normal chest Xray in early or mild disease. 
CT Chest with typical GGO

Normal Chest Xray of the same patient 

CT protocol is non-contrast spiral chest CT. Iodinated contrast medium is only indicated when one need to do CT pulmonary angiogram (CTPA) for suspected pulmonary thromboembolism.

Primary findings of COVID-19 on chest radiograph and CT are those of atypical pneumonia or organizing pneumonia. The most frequent is airspace opacities, often described as consolidation and ground-glass opacity, often bilateral, peripheral, and lower zone predominant. Fibrotic bands and traction bronchiectasis can be seen when the disease is resolving.
Pleural effusion and lymphadenopathy are rare, rather they are not the features of the disease.

Other common ancillary lab tests which are performed in a hospitalised patient are CBC for lymphopenia, increased prothrombin time (PT), increased lactate dehydrogenase, CRP, ESR, D-dimer, serum amylase. Mildly deranged liver function tests are common, primarily elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Alkaline phosphatase (AKP) and gamma‐glutamyl transferase (GGT) levels remain normal.

Complications during the disease which contributes in mortality are acute respiratory distress syndrome (ARDS), acute thromboembolic disease, pulmonary embolism, acute cardiac injury due to elevated troponin levels, myocardial ischemia, cardiac arrest, myocarditis. These complications are more common when there are associated comorbidities like obesity, older age, and diabetes.

Rx, no definitive treatment or vaccine exists as of now however, dexamethasone, a kind of steroid has a crucial role in changing the outcome of clinically bad patients. Antiviral therapy such as Tab Fabiflu recently launched in the market and is available with a prescription.

Spinal Osteoid osteoma


Osteoid osteoma

A benign bone tumour, typically occurs in children and adolescents, more common in males. Characteristically present with night pain which is relieved by the use of salicylate analgesia such as aspirin.
They are a classic cause of painful scoliosis when occurring in spine, concave on the side of the lesion. Soft tissue swelling and oedema may occur and if close to a growth plate, accelerated growth may be evident, may be related to hyperemia.
Most osteoid osteomas occur in long tubular bones of the limbs such as femur and tibia.
The femur is the most common location especially the neck of femur. The mid-tibial diaphysis is the next common location.

Osteoid osteomas are usually cortical lesions with adjacent sclerosis which is reactive and does not represent the lesion itself. 
The nidus is usually less than 2 cm in diameter and is typically ovoid in shape. Associated solid periosteal reaction with cortical thickening on x-ray or CT. The nidus is sometimes visible as a well-circumscribed lucent region, occasionally with a central sclerotic dot. 

CT is excellent at characterizing the lesion and is the modality of choice. 

Nuclear medicine, skeletal scintigraphy will show typical focal uptake and at times will show a double density sign.

MRI is sensitive, but is non-specific and is often unable to identify the nidus due to associated bone marrow and adjacent soft tissue oedema.

The lesion is benign and treatment has traditionally been with surgical resection. 

General imaging differential considerations include:

osteomyelitis, Brodie abscess
osteoblastoma more than 2 cm in size
stress fracture
cortical desmoid
osteochondroma
osteosarcoma
enostosis 
localized cortical thickening
intracortical hemangioma