Vertebral artery thrombosis

On MR Angio, non visualization of a vessel or a part of vessel needs careful interpretation as it can be due to many reasons right from thrombotic occlusion of vessel, absent vessel as a part of normal anatomical variation or a technical error while doing post processing of raw images of 3D TOF sequences by using add vessel technique.
So diagnosis of vessel thrombosis or passing it off as a normal anatomical vessel should not be solely based on MR Angiography findings.
The diagnostic dilemma occur more so when there is no infarct in corresponding vascular territory.
This problem is most common with vertebral where one of the vertebral is not visualised. Opposite vertebral continues as basilar. In such cases we can take help of other routine parenchymal sequences like FLAIR and T2*GRE.

In above case, thrombosed distal most portion of right intra cranial vertebral near formation of basilar show a focal flow loss on MR Angio, the corresponding portion show an abnormal low signal on T2*GRE and high signal on FLAIR implies to thrombus. 

Cavernoma with popcorn ball appearance MRI

Flair

T1w

T2w

T2*GRE

Imaging findings of Cavernoma (Cavernous Malformation) are very typical on MR as in this case. 

A right parietal cortical focal lesion with typical "popcorn ball" appearance, few T1 bright locules of Meth Hb with a low signal intensity hemosiderin rim on T2 w images. 

No perilesional edema on FLAIR. 

No mass effect or volume loss. 

Blooming on GRE due to paramagnetic effect of blood degradation products. 

Similar case : Cavernoma-cavernous-malformation

Cavernoma (Cavernous Malformation)

A benign vascular hamartoma, composed of closely packed immature blood vessels with intra lesional micro hemorrhages, without any neuronal tissue.

Imagingwise best diagnostic clue is "Pop corn ball" like appearance with hemosiderin rim on T2w images.

Occur anywhere in brain. Rare in Spinal cord.

Vary in size from few mms to cms. Average size is between 1 to 5cm.

Usually single solitary, may be multiple, discrete lesions.

CT / MRI

Hyper dense on non contrast CT. Punctate Calcifications seen in ~ 50% cases. None to very faint enhancement on post contrast.

On MRI, lobulated appearance due to multiple locules which show variable signals, depending up on the blood degradation products. T1 bright locules attributed to Meth Hb - a sub acute stage blood degradation product. Low signal intensity hemosiderin rim on T2w images. The complete lesion will show low signal intensity blooming on  T2*GRE images. No to faint enhancement on post contrast T1 images.

No to very minimal Peri lesional odema on FLAIR. 

No mass effect.

Clinical presentation

Seizures 50%

Neuro deficit 25%

Asymptomatic 20%, detected as an incidnetal finding.

No intervention is a rule. But need follow up imaging as it may show progression or regression in size. Rarely show massive bleed.

Can affect any age group.

No gender preponderance.

Familial association in Hispanic Americans - Multiple Cavernoma Syndrome, carries higher risk for bleed and re bleed.