The hyperintense vessel sign, also known as the dot sign, is sometimes seen on fluid attenuated inversion recovery (FLAIR) MRI brain sequences in reversible cerebral vasoconstriction syndrome (RCVS).
The hyperintense vessel or dot sign is only seen on FLAIR MRI brain sequences, and describes a hyperintensity within the deep sulci, indicative of a focally dilated cortical artery within which there is likely very slow flowing blood, often in the setting of a more proximal arterial stenosis 1-4. Depending on the orientation of the artery and the imaging plane, the dilated vessel may appear as a dot-shaped or a linear-, tubular- or serpentine-shaped hyperintensity 1-3.
The hyperintense vessel or dot sign may be a common finding in reversible cerebral vasoconstriction syndrome (RCVS) 2,3, and its presence may be associated with more severe disease 1. Depending on the study, the sign may be present in 22-70% of patients 1-3. As the condition was treated and improved, the sign was demonstrated to disappear within 6 weeks in one study 1.
It is important to note that the hyperintense vessel or dot sign can also be seen in other intracranial vasculopathies whereby there are focal arterial stenoses and dilations, such as central nervous system vasculitis 4.
Differential diagnosis
convexity subarachnoid hemorrhage: unlike the hyperintense vessel or dot sign, the abnormal high FLAIR signal will tend to follow the entire sulcus, be less well defined, and will be associated with low signal on GRE/SWI MRI and hyperdensity on CT 1
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