 Welcome to our neuroimaging board and recredentialing review where we're focusing on infection and inflammation. We have an adult with third nerve palsy, a headache, high fever. Let's have a look at the images. An axial MRT2 water weighted. A fluid attenuated or flare image on MR. An axial T1MR without and with contrast. An axial T1 inversion recovery with contrast. An axial diffusion weighted image. And two coronal images. A coronal T2MR and a coronal T1 contrast enhanced MR. Let's take our first question, shall we? Number one, the most likely diagnosis is A, carcinomatous meningitis. B, tuberculosis. C, sarcoid. D, radiation effect. E, eosinophilic granuloma or Langerhans cell histiocytosis. Question number two, angioinvasive infections include all except. A, syphilis. B, West Nile. C, tuberculosis. D, aspergillosis. Question number three, multiple forms in the neural axis with tuberculosis involvement include all of the following except. A, cisterns fill with gelatinous exudate and leptomeningial enhancement were affected especially circle of willis. B, hydrocephalus. C, infarctions especially in children. D, cranial nerve palsies. E, POTS, puffytumor or pseudomass of the hypertrophy adenoids. Let's go back to our images and have another look. In the left putamen and portions of the corpus striatum there is an ill-defined non-mass-like pattern of hyperintensity which is corroborated on the flare sequence with little evidence of ventricular shift. The atria of lateral ventricles may be a little dilated but we'll keep an eye on those as we always should in any neural case. The pre- and the post-contrast T1MR are revealing. There is an incredible amount of enhancement in the region of the circle of willis and in the basal cisternal region with dilatation of the temporal horns consistent with the diagnosis of obstructive hydrocephalus. So this patient with a high fever is sick. They're sick by virtue of the imaging analysis and they're sick by virtue of the history. The axial inversion recovery image shows once again extensive cisternal enhancement following the course of both middle cerebral arteries and arcing around the mid-brain in the juxtacalicular plate cistern posteriorly. The diffusion restriction image shows a little bit of diffusion restriction in the corpus striatum in other words high signal intensity suggesting that there is perhaps vascular compromise or diffusion restriction of another etiology. Finally the coronal images show that same area of ill-defined signal in the left subfrontal region and corpus striatum with once again additional imaging showing enhancement of the cisterns and look how far out that enhancement goes even though it's subtle and scant. Let's return to our questions. The first question the most likely diagnosis is B. tuberculosis so why isn't it carcinomatous meningitis? Well the history doesn't support that a high fever but also why would carcinomatous meningitis just settle in the brain base and not in any way affect the convexities? No this is something heavy like an exudate or heavy particulates or perhaps a fungal infection that has a large size to it for each of the fungi or tuberculosis which is a relatively heavy exudate that settles in the brain base so-called basilar meningitis and this is a characteristic of TB but what about sarcoid? The great masquerader of tuberculosis. Sarcoid non-casiating tuberculosis casiating but that's a pathologic diagnosis we can't tell that on MR. So what supports the diagnosis of TB over sarcoid? They both are noted for their ability to produce cranial nerve palsies that sarcoid patients are not sick. Sarcoid patients do not have a high fever. Sarcoid can produce isolated cisternal involvement but frequently sarcoid has multiple areas of involvement parenchymal, cisternal, ventricular and so on but I think the key here is the fact that the patient is sick and has a high fever. Radiation effect. This would not be located at the brain base alone and typically you don't get leptomeningitis from radiation effect but you can get pachymeningeal or dural thickening which is smooth but not isolated at the brain base. This is not a viable choice. And finally eosinophilic granuloma or Langerhans cell histiocytosis also not a viable choice. This is not characteristically a leptomeningial or meningial disease of any kind. Question number 2. Angioinvasive infections is a favorite question. Include all except and the answer is West Nile. West Nile virus West Nile is a viral infection. Viral infections typically are not infarctive or angioinvasive while they can be catastrophic. They can produce infarcts. It is not a typical feature of most viral infections and especially West Nile where there is a very high percentage of individuals that are hardly even symptomatic. In fact the majority of patients affected with West Nile never even know they have it. But syphilis, tuberculosis and aspergillus are the big three you can remember with the mnemonic SAT for the SAT exam. Those are the big three that are angioinvasive and are noted for their ability to produce secondary infarction and perhaps that is what's causing the diffusion restriction in the left corpus striatum in this patient. Question number 3 tuberculosis involvement in the neural axis includes all the following except and the answer is POTS PUFFY TUMOR. POTS PUFFY TUMOR with involvement of the calvarium with a soft tissue mass protruding anteriorly is in no way reminiscent of a pseudo mass of the hypertrophied adenoids which are not even in the central nervous system. So this is a pretty easy one. Easy to identify the wrong answer which means the rest of the choices are correct. Cisterns do fill with gelatinous exudate. Leptomeningial enhancement is intense or dense and sometimes that density appears as hyper density on CT. There is a predilection for the basal cisterns especially around the circle of willis as in this example. Hydrocephalus is common, this patient has it in infarctions, not uncommon with TB aspergillus and syphilis and especially in children. This patient is probably brewing in infarct in the left cerebral hemisphere. Craneal nerve palsies are a common component of tuberculosis also sarcoid but we've identified why this is TB and not sarcoid. That concludes our discussion on intracranial tuberculosis and you'll see a lot more tuberculosis in our educational programs. Let's move on to the next case.