 In this video, we will discuss about perivascular spaces and their mimics. Perivascular or virtual robin spaces are commonly seen on routine MRI. They are fluid filled spaces surrounding small arterioles, capillaries and venules in the brain. These usually have characteristic locations, imaging appearances, and are commonly incidental findings with no clinical implications. These are generally of four distinct types. Type 1 perivascular spaces are located in the anterior perforate substance and are very commonly seen on routine MRI imaging. These images show acystic lesion in the right anterior perforate substance. On the coronal imaging on right hand side, a thin linear traversing vessel can be seen within the lesion. Images from the same case as above showing complete suppression of T2 hyperintense signal of acyst on flare and enhancement of the vessel on contrast enhanced T1 image. Another case showing multiple perivascular spaces in common locations, that is the right external capsule and left lentiform nucleus appearing hyperintense on T2 with complete suppression of the signal on flare. Contrast enhanced images of the same case as above showing no enhancement of the perivascular spaces. Images of 75-year-old patients showing multiple perivascular spaces in bilateral basal ganglia and thalamine, which are completely suppressing on flare. These are called etat crible or status cribrosum, and the appearance is also described as Swiss cheese. Multiple linear perivascular spaces are also seen in bilateral white matter. There is concomitant chronic small vessel ischemic changes in ganglion thalamic regions and white matter better appreciated on the flare image. Coming to type 2 perivascular spaces, there is a lobulated multi-cystic lesion in right frontal lobe appearing hyperintense on T2 with complete suppression on flare. There is no evidence of guiral thickening, mass effect or any perillational edema. These findings are characteristic of type 2 perivascular spaces and should not be mistaken for a DNET or Decemberoblastic neuropithelium tumor. This is another example of type 2 perivascular spaces. Another lobulated multi-cystic lesion is seen in left frontal lobe appearing hyperintense on T2. There is mild surrounding white matter hyperintensity. However, it is important to note that the lesion suppresses completely on flare. There is no evidence of guiral thickening or mass effect suggesting type 2 perivascular spaces. Another case showing multiple confluent subcortical white matter cystic areas appearing hyperintense on T2 in left frontal lobe giving an ominous appearance. Images of the same case as above show complete suppression of the T2 hyperintense signal on flare. There is no evidence of perillational edema or mass effect. No evidence of thickening of the overlying cortex is seen. On post-contrast even images there is no enhancement of the lesions. Overall, these findings are suggestive of tumor-factive perivascular spaces. This case was actually previously reported as a neoplasm. Type 3 perivascular spaces are located in and around the brainstem. There is a cystic lesion with septations involving the brainstem extending into the right thalamus and causing compression of the aqueduct and posterior thylventricle resulting in hydrocephalus. These are probably the only perivascular spaces which will require a neurosurgical intervention to relieve the hydrocephalus. Type 4 perivascular spaces are located in the temporal lobes. In this case there are multiple tiny cystic areas in anterior aspect of right temporal lobe appearing hyperintense on T2 and completely suppressing on flare. However, there is no evidence of guiral thickening, mass effect or any surrounding edema. These findings are characteristic of anterior temporal lobe perivascular spaces or type 4 perivascular spaces. These are recognized as a distinct variant of tumor-factive perivascular spaces as they often have perillational edema ranging from mild to extensive. Now coming to a few mimics of perivascular spaces, this is a case of BNET or disembryoblastic neuropathy lateuma. This case shows a cortical base lesion in right frontal lobe which appears heterogeneously hyperintense on T2. There is partial suppression of the T2 hyperindense signal on flare. Note the evidence of guiral thickening. A coroidal fissure cyst can be made out with its characteristic location. There is a cystic lesion in the region of left coroidal fissure operating the left hippocampus. It appears hyperintense on T2 and suppresses completely on flare. There is no mass effect or perillational edema. Another mimic of perivascular spaces is a multinaudular and vacuulating neuronal tumor or MVNT. This case shows multiple nodular T2 and flare hyperintensities in the subcortical white matter of left medial temporal lobe abutting the overlying cortex, left hippocampus and possibly involving them. There is no evidence of guiral expansion or mass effect. These findings are characteristic of MVNT. This one is probably the easiest one to distinguish from a perivascular space. There is a cystic lesion with dot-like hyperintensity within, likely representing a scolex. On flare images, there is near-complete suppression of the T2 hyperintense symbol. Findings which are characteristic of neurocyste supposes. Thank you for watching the video. If you like the video, please press the like button, subscribe to our channel and press the bell icon for notifications. Thank you.