 now come into the venous anatomies. So here you can see that this is a MIP image of your top venosequence and this is something for our residents they are always asked to draw this kind of diagram in their exams. So this is a sagittal projection and you can see that the important venous sinuses which we often identify are these superior sagittal sinus which should be completely seen as hyper intense area. Then you have this area of tocula. When you see this we have seen in the mid-sagittal anatomy top also the area of vein of gallin internal cerebral vein the ones the major tributaries here are the veins of prolact that is easily seen. You have your inferior sagittal sinus somewhere here but most of the time these are not identified on top sequences. So these are the important ones and your vein of label is inferior from the transverse sinus. So you can see the transverse sinus and sigmoid sinus better on this frontal projection, reconstruction, vein of trollad, superior sagittal sinus, transverse sinus, sigmoid sinus continue into ITV. One of the most common variants is hypoplasia of these transverse and sigmoid sinus which is more commonly seen on the left side but sometimes on top and you it can be confusing or top you know it can be confusing and you may think that this is thrombose that time you can go ahead and perform a post contrast venogram which will clear our doubts and after the post contrast venogram immediately you can perform a 3D T1 weighted sequence post contrast which will be another sensitive way to identify any flow world in the venous channels and identify the thrombosis. So another graphical depiction superior sagittal, inferior sagittal, vein of trollad, vein of label, cavernous sinus so we will see that in detail. So this is your cavernous sinus so and we have to understand the drainage of cavernous sinus the tributaries which are draining into and from the cavernous sinus. So this is an area which can lead to a lot of important pathologies and then their symptoms will be related to all these cranial nerves which are crossing the cavernous sinus. So that is located on either side of the pituitary fossa that we all know and body of the spinoid bone. So unlike other neural venous sinuses it is divided by multiple fibrous septae into small cave like structures so that is why it is called as the cavernous sinus. So the vascular connections where it receives its blood from are inferior and superior ophthalmic veins. So if there is cavernous sinus thrombosis and the thrombus may extend into the ophthalmic veins but there will be areas of ophthalmic congestion and swelling. As we know in cases of even the toloxahunt syndrome there can be cavernous sinus thrombosis associated and then superior ophthalmic vein involvement. Drainage of the cavernous sinus is into the superior pituitary sinus and then to the transverse sinus via the inferior pituitary sinus directly into the jugular bone. So we cannot remember each of these points but at least the important things we should try and remember. These are little easier diagrams to draw in your exam if you are a resident. So you are asked the drainage of cavernous sinus so here you can see how it is connected to various other sinuses and venous channels superior orbital fissure and the inferior ophthalmic vein coming into the cavernous sinus and then the cavernous sinus getting ahead and draining into the major sinuses. Normal variants in the venous channels and the dural venous sinuses is something which is very very common and there are articles people have published using over 1000 patients whom they have scanned for various purposes. So most of the time it is left sided hypoplastic transverse sinus, left sided atritic transverse sinus, right sided hypoplastic after that sigmoid sinus again hypoplasia as unknown. So that is one thing another is there are a lot of variants so if you see your image and you find that something is funny something is odd not as usual just go back and search for the variants and you might find your diagnosis. So these are another graphical examples of various kinds of connections the dural venous sinuses can have. This is one important spotter question this is occipital sinus another variant of the venous sinus drainage. Erythmic granulation can sometimes mimic your intra venous sinus thrombosis so that has to be carefully see. So that's why I told you that only one sequence top venous is not sufficient you might require post contrast venous which is more sensitive you have to correlate with your 3D flare sequence for loss of flow while you have to correlate with your T2 whatever axial or coronal you have obtained. Post contrast 3D T1 are really important because you can see these small arachnoid granulation clearly or if there is a thrombus that also can be seen as a area which is non-enhancing and even your gradient or swan images are important to pick up small areas of venous thrombosis. Only one I'll see is that sometimes acute thrombus can be hyper intense on plain T1 only so on post contrast even it will look as if there is complete contrast opacification so that time you have to be careful and you can compare with your pre contrast even so once somebody asked in a conference to an expert that which sequence is the best to pick up venous sinus thrombosis so that time also the answer was it has to be a combination of sequence sometime it can be difficult with one. So yet another important aspect arterial versus venous infarcts so like there are arterial territories there are venous territories so when you see an area of infarct which is little odd not fitting into your arterial territories your angiogram looks normal and that area of infarct is showing a lot of hemorrhage within you suspect that it is venous not an arterial infarct then you can compare with these kind of graphics where they have depicted the areas of venous territories and you can pick up which particular venous channel is likely to be thrombus so this is a short table of difference so this is not what we are discussing right now but just revising venous infarct due to congestion as we know so there will be a lot of intralisional hemorrhages then may reward the edema may reward onset of symptoms is insidious and angio is normal we know will show the finding arterial infarct will follow their own territories they are ischemic in etiology MR angio will pick up the arterial cutoffs reversibility will take time intralisional hemorrhages acutely are less common so few more sets of images showing us the territory of venous drainage so parasagitally here you have your inferior sagittal sinus the blue ones are for your internal cerebral veins so another good spotter where you have bithalamic or areas of restricted diffusion with hemorrhage so we'll see that with few examples skipping this one just taking two three important subsets of cases so deep cerebral vein thrombosis is something which can be missed if you don't suspect it on a plain CT scan you can find out symmetric areas of hemorrhages which are there present in the areas of bithalamic and that can be because of deep cerebral vein thrombosis so internal cerebral vein thrombosis may be picked up as hyper densities on your CT images and MRI can show you clearly that there will be your blooming on swan edematous salami hemorrhage and infarcts and thereafter when you perform a good quality venogram and post contrast even can pick up these thrombosis so cavernous sinus thrombosis is another important entity to diagnose and here you have to see thin sections from the cavernous sinus taken in coronal plane they have to be T1 stir and post contrast even and then you see a symmetric distention of the cavernous sinus with non-enhancing areas with it so nowadays with the short epidemic of mucar mycosis we saw a lot of cases with enhancing and then non-enhancing tissues in the orbital apex and invasion of the cavernous sinus so period of thalamic vein thrombosis very fairly enhancing the standard of thalamic veins with non-enhancing areas within. Particle venous thrombosis may be missed easily if you just see your top pino so you have to carefully see your 3D scone sequences where you are going to find particle areas of blooming going along the cortical vessels and patient might have chronic headaches so this is something which might be missed only if you see the venograms so to summarize what is important is anatomy is something which requires revision and there are lot of variations in the anatomy which may create confusion sometimes so we can always refer to our resources and references and also look at the source images whenever possible for angiograms and venograms