 What I will be doing in the next 15 minutes is talking about how imaging of brain tumors has changed over the last decade or so and what is the current status of role of MRI including its multi-parametric parameters in terms of the current status. There have been several advances in brain tumor imaging over the last decade, decade and a half. The brain tumor imaging has changed completely from pure anatomical imaging to vascular metabolic and functional imaging. Use of MRI as a diagnostic tool has progressed from completely anatomical imaging to functional imaging. This allows neurosurgeons to plan surgeries in a very sophisticated manner. It is effective in assessing treatment response when you are giving chemo or radiotherapy post surgery. It differentiates true progression from sugar progression and it also differentiates true response from sugar response and this has allowed the oncologist, the radiation oncologist and surgeons to understand the tumor behavior much better. It also allows a good detection and assessment of what is going to happen to the patient in a much sophisticated manner. So the routine conventional sequences in tumor imaging in central lung system has moved from simple spinicosequence, gradient echo sequence, fast spinicosequence, inversion recall sequence, flare sequence to a lot of new basic and advanced sequences in terms of a mass spectroscopy, diffusion and diffusion tensor imaging, perfusion imaging, R2 spin levelling which is a part of perfusion imaging without having to inject contrast. The true functional imaging which is bold imaging and fusion imaging when these functional and structural imaging is combined together it gives a complete information. This allows the medical oncologist, surgical team and radiation oncologist greater insights into grading of tumor characterization of tumor functional and anatomical localization of tumor. It also allows better understanding of secondary effects on the adjoining white matter tracks, eloquence cortices, etc. It allows better operating planning, response to treatment as I said, pseudo response or true response and it allows much more accurate information about whether there is a recurrence of the tumor or there are post treatment changes. So tumor protocol has changed completely from just a simple and abnormal imaging to functional imaging and that is what we are going to understand in next 15 minutes. So each of these new sequences provide very unique information which when combined together has implications for defining the tumor type and grade better, directing biopsy or surgical dissection better, planning radiation and biological therapies in a much accurate way. It also assesses the treatment response much earlier, quicker and better than what we were doing before and it also allows the researchers understanding mechanism of success and failure of newer treatments, typically anti-adjusionist therapy. So what are the newer sequences in MRI that allow this functional information better? So you have spectroscopy, diffusion tensor imaging, perfusion imaging, arterial spin learning, functional MRI and fusion imaging. In this part of the lecture we are going to cover only spectroscopy and diffusion and diffusion tensor imaging and in the next part we are going to cover the other four sequences. So let's start with understanding spectroscopy and its role in differentiating malignant brain tumors from benign bones. There is a lot of data available across literature but what is bandage followed is this meta-analysis covered by AJNR in 2006 which talks about higher ratios of colline upon creatine with cutoff of 2 colline upon NA with cutoff of 2.2 and colline plus creatine upon NA and creatine upon NA to decide that you are dealing with a hygrate tumor. Lower ratios of lipid upon lactate and creatine upon lactate is also considered as a patient suffering from hygrate tumor. Metastasis can be differentiated from hygrate hormones by presence of high lipid creatine ratio. So what are the practical applications of MR spectroscopy? It distinguishes abnormalities with same imaging appearances and the examples are differentiating tumor from radiation necrosis, differentiating cystic tumor from abscess, differentiating metastasis from astrocytoma or gliomas and differentiating toxoplasma from lymphoma when patient is immunocompromised and here are actual examples. So these two legions morphologically look quite similar although the size is different and it will be virtually impossible to differentiate glioma from metastasis. Then look at spectroscopy. So if you have presence of MI and presence of creatine that indicates that you are dealing with glioma also in the peritumeral area what looks like edema if you have presence of colline that indicates you are dealing with an astrocytoma or glioma. Metastasis on other hand will have complete absence of intratumoral colline as well as intratumoral MI. It will show lot of lipid which will be absent in glioma. So that is the way to differentiate glioma or primary tumors of brain versus metastasis. Lymphoma can be differentiated from these two entities by presence of what is called as twin peak sign. So when you have two top peaks of liquid lactate and colline you know you are dealing with lymphoma. Oligodendroglioma on the other hand will have relatively low colline high creatine and high MI glycine. So it's impossible to differentiate glycine from MI because both resonate at the same location. Also if you add the presence of tumor mainly in gray matter with infinitive pattern you know you are dealing with oligodendroglioma and not astrocytoma or glioblastoma. Relation necrosis can be differentiated from recurrence of a tumor by tall lipid lactate peak from 0.9 to 1.3 ppm with relatively low colline. So when you have post tumor bed evaluation you want to differentiate recurrence of a tumor from radiation necrosis. Run a multivoxin spectroscopy and look for in the tumor bed presence of high colline that would indicate presence of recurrence. If across all the voxels there's only high lipid and nothing else you know you are dealing with the relation necrosis. So relation necrosis will have low colline high lipid lactate tumor recurrence will have high colline and high colline in a ratio. So that are the role of MR spectroscopy in brain tumor imaging. Let's now go on and see how diffusion and diffusion tensor imaging helps us in differentiating high grade vammals from low grade vammals or ME other entities. How does diffusion work? It is basically an index of free motion of water in the intra and excess cellular compartment of the brain cells. Anything that has high viscosity or high membrane would include motion and will show restricted diffusion. So any region with high similarity, so we are talking about high grade vammals will have restricted diffusion. Anything that contains pus so we are typically talking about abscess will show restricted diffusion. So restricted diffusion will be seen in abscesses and high grade cellular that means high grade tumors. Based on this again the same article of AJNR in 2006 allows us to talk about differentiating high grade vammals from low grade vammals by looking at diffusivity. So high grade vammals will show lot of restricted diffusion, low grade vammals will show facilitation of diffusion, intermediate grade vammals will show relatively less restricted diffusion. Abscesses will show restricted diffusion in the center whereas if it was a cystic tumor, the solid component or peripheral component of the cystic tumor would show restricted diffusion. Diffusion tensor imaging is an extension of diffusivity, a non-invasive way of understanding brain structural connectivity. It also allows us to look at microscopic axonal organization of white matter tracts and based on the directional rate of diffusion of water molecules we can see where the diffusion is facilitated more and where it is not. So little bit of more understanding of diffusion tensor imaging when we say that hydrogen atoms in the intra inaccessible compartments are flowing at a rate of 5 centimeters per minute that's not a complete truth. So along the white matter tracts the water molecules are moving at 5 centimeters per minute perpendicular to it the diffusivity is virtually zero and what we see in tumors and in lesion is something in between. So we calculate fractional anisotropy and look at how the diffusion is. So wherever diffusion is maximum you will see more restricted diffusion that is in high grade tumors and when it is lesser you will see facilitation of diffusion that is called as FA and based on the fractional anisotropy tracts which are in transverse axis are labeled as red those superior interior are labeled as blue and those anterior posterior are labeled as green and color use depend on the intensity of FA. What are the practical applications of DTI? It allows track specific localization of white matter regions it allows localization of tumors in relation to white matter tracts it differentiates infiltration from deflection and that is important in grading the tumors. It allows localization of main white matter tracts for neurosurgical planning and it also detects occult white matter invasion by high grade gliomas. So based on the pattern of DTI you can actually decide which tumor you are dealing with for example in gliomas and metastasis the tracts will be displaced whereas in anaplastic astrocytoma and GBMs the tracts will be infiltrated but they will remain identifiable in very high grade anaplastic astrocytomas and gliomas tracts will be completely disrupted whereas in metastasis and in edema the tracts will be normal but just displaced with slight change in the color view and these are the actual example this is a left frontal lobe polyurental glioma the tracts here are displaced but not infiltrated compare that with another pontine glioma which is a lower glioma again the tracts are displaced and not invaded compare these two patients with this patient of the one that I showed you before a glioblastoma multiform in left temporal lobe the tracts are completely destroyed here is another example of DNA in the left posterior frontal cortex the tracts are displaced color views are slightly changed but there is no infiltration so that is the importance of diffusion and diffusion tensor imaging in advanced tumor imaging. Perfusion, artisan labelling, functional MRI and fusion imaging will cover in the next talk so to conclude this part of the talk with integration of conventional and advanced imaging techniques we can provide increasingly detailed information about the underlying pathology these details will aid in improving our understanding of brain tumors and help in development of new treatment strategies in future what we also need to understand is radiology has to be both image centric and patient centric we must understand that we are an important and an integral part of patient treatment inter-speciality communication coordination is most important and we must aim to change from volume based to value based imaging from interpretation focus to outcome focus reporting and the responsibility of training our future generation with not only the advances but these values lies with us thank you for your attention