 Good morning, everyone. A warm welcome to you all. And on behalf of Indian radiologists, I would like to welcome you all to the radiology general club today. This is a slightly newer concept and we've had two general clubs so far. The first one was in September, which was a neuroengineering which was taken up by Dr. Nikushar Bhadma. The second one was last month on rest of the chain where we had with us Dr. Shilpalad. I would like to thank you all for your participation and we've received some excellent feedbacks. Also, since it's a newer concept, your feedback and suggestions are completely welcome. So do let us know if you have any ideas or anything you would like us to include in this. We've had article discussions and case discussions in the last two sessions. We would like your interactive participation as well. So do let us know if you have anything in mind, you can contact either Dr. Mitusha or me, Dr. Gauri. And we definitely try to incorporate those in our future programs. Before moving on, I would like to thank our core organizing team at Indian radiologists, Dr. Shalini Singh, Dr. Jitmesh Thakkar, Dr. Sanjeev Manisa, Dr. Deepak Patrasar. Their support and their encouragement is what keeps us going and nothing of the sort would have been possible without that. So thank you so much. Also, the other members of the team are Dr. Mitusha Verma, Dr. Shilpa Ma'am who was there with us for breast imaging, Mamta Ma'am and Dr. Amit Poonkar who's always there for technical support. Obviously, Dr. Amiya Kolkani who will be taking care of the radiology journal club today in body imaging. Thank you all of us, all of you. So the idea behind the program is very simple. It's basically just to stay updated. We will be discussing advances and research articles, interesting cases, something new that helps you to be in touch with what's going on, new protocols, anything that comes up new and helps you going. So this is all going to be discussed in a very interactive fashion as well. Also, all this will be streamed on YouTube so you all can go back and go through it again if you all wish. The case articles that we discussed will be shared with you like we shared them last time. So you all can go ahead and refer to those later as well. So moving on, I would like to thank our educational partners. Bear, thank you Kedar, Kanchan, everybody at Bear for your support. It is this what keeps us going so thank you so much. Along with Bear, we also have Phantom Healthcare with us this year and thank you so much once again for your continued support. Before moving on, I'm really excited to announce that we're coming up with our sonobas in January. That's on 8th and 9th of Jan in Mumbai. We've had two sonobas so far. This is the third event. The last one was an online event. This year it's going to be hybrid so we have an onsite as well as an online program. We have an excellent panel of national speakers for you. It's a complete fetal ultrasound program so please go ahead and register for the same. There are some interesting concepts like the fetal phase contest. So do send your entries. We'll be sharing the details in the chat box as well as on all our platforms. And do send us your paper and poster entries as well. We will share the details with you. So coming to today's program, the Stadiology Journal Club will be on body imaging. We have with us Dr. Amir Kulkarni who's joining us from Canada for the same. So we'll be discussing the article which is on wasn't a classification of sister criminal masses and a couple of cases related to the same. So it's my pleasure and honor to introduce Dr. Amir. He's a staff radiologist at Jurewinski Hospital of Hamilton Health Sciences. I'm an assistant professor at McMaster University. His specialty is in western body imaging. It's a pleasure to have you with us, Dr. Amir. I think you can take over from here. Thank you for those kind words, Gauri. First of all, thank you, Indian radiologist for allowing me to participate in today's general club. This is something which I always kind of think every day, day in and day out when I'm reporting my CDs or MR examinations, that how to deal with certain kind of renal lesions. So without any further for the deal, I'm going to dive into today's sessions. A couple of couple of housekeeping things to discuss today. There are at least a couple of slides where I will be asking you to take out your take out your cell phones and have their cameras ready so that you can use or scan the QR code which I'm going to show you to access some really important websites that are recommended by the readers as well as the authors of this paper. And then this is going to be an interactive session so there will be two quiz questions which I will show you in the first session of this general club and the answer will be showed at the end of the presentation. So make sure that you answer those questions on the polling session. Thank you for the presentation if you have any questions please feel free to use the Q&A feature type your answers there, I'll be able to get back to those at the end of the session. And then as we go through it if there's anything which you want me to do I'll be happy to stop go back to that slide as well. So make sure that you also pay attention to the slide numbers as I'm scrolling through them. So for example if you have question around like say slide number 23 or something like that I can always go back to that slide and we can discuss that later on. So without any further deep further do let me start with the paper today so the paper which we are going to discuss was published recently in Radiographics Journal, and it is something which is a really really important topic which you should be paying attention to when you're reporting your CTNMR examinations. The reason why I'm talking CTNMR is unfortunately Alpha Sound fails to characterize some of the findings or the some of the features which are associated with the cystic masses will come to those things in the final details of the paper. So let's look at the first polling question here so pay attention to these three images case number one case number two and case number three you have a sagittal CT image on the case number one, it shows a partially exorbitant from the lower part of the kidney, then you have your case number two which is a transverse image of the kidney. I think the whole question is right on the case there let me try to see if I can move it around. Okay, that looks better. So case number two is an actual post contrast CT of the kidney through the mid pole region. And then the third option is case number three, which is an actual post contrast MR which shows a large heterogeneous mass. So please feel free go ahead and type in your answers what do you think when you can apply Bosnia classification case number one case number two, or case number three. Okay, so I will keep the results to myself but there's a little bit of a split here, but most of your answering case number one. And then, let's go to the second polling question here. So can we restart the poll again for the second question. So the second polling question is slightly different now so I have given you three images case number one is a sagittal grayscale static artisan image of the kidney which shows a partially exorbitant system legionizing from the lower pole. So the case number two is an actual tissue image which shows this intermediate T2 bright legion in the mid pole cortex of the kidney and case number three is actual post contrast T1 image which shows a cystic mass which shows enhancing septic. So the question is that when will you use Bosnia to F or higher category amongst all these three instances so just type in your answers whether you think that it's case one case two or case three. So I guess most of you are answering correctly already which is good. I don't have to spend a lot of time on those things. Excellent. Okay, so now we have some some little bit of an idea about what we are going to deal with today. So with this knowledge, let's go into the article so the article which we are discussing is that will add Bosnia class because of cystic masses version 2019 a pictorial guide to clinical use those are the authors who have put in lots of effort to make this a really nice pictorial guideline. And this was published in radio graphics me to June 2021 issue. These were the disclosure this put forward by the authors of this paper. So now before we go into this paper I want to discuss some background as to what is the reason why the Bosnia guidelines were changed or updated to begin with. The most important problem which starts is that what is the reported malignancy rate amongst all these Bosnia categories category one, two, two, three and four. If we still use the older origin which was mildly updated in 2012, especially around the city finding some of the things were included in 2012. So, when they went back and did an amazing systematic review in 2017, they came up with this kind of interesting discovery that the reported malignancy rates were quite variable. And they were up to 17% in Bosnia 12 categories. However, the biggest challenge was that Bosnia three and four, which are supposed to be highly suspicious for malignancy. So, these are the most likely significant rates of reported benign lesions. So which means that these patients underwent part in the spectrum in the spectrum to excise a lesion, which was characters as Bosnia three or four, but approximately 50% of Bosnia three lesions turned out to be benign, and around 10% of four, they ended up being benign, which is not the entire purpose of why these lesions were being followed up. This is interesting when you go in and check some more data. So this was data which was published in surveillance epidemiology and end results database from 1975 to 2015. So the blue line here on the top is essentially the incidence of cystic RCC. So as you see with increasing spatial resolution of MRs and CTs, you're detecting more and more of such lesions now, but it fails to have any significant impact on patient mortality, or significant incidence, which means that you are probably over diagnosing or over treating these lesions. And it further confirms this theory by putting in together what are the death rates for 10 years in patients who have P1A stage cancer. So these cancers will be less than four centimeter in size and masses limited to the kidney. This death rate is only 0.2% amongst all of these treated or excised lesions. So in a nutshell, it is causing a little bit of too much harm to the patients when we are stratifying these into Bosniac 1, 2, 3, and 4, especially using the older Bosniac terminologies. And this is when they started working. The 2017 systematic review was the catalyst to change most of the things in Bosniac 2019 version. So let's look at the problem a little bit closer. So now, once we know what is happening, you're picking up more cystic lesions. Sorry, I think Pat Kruse's audio was on. Second is coming, right? Yes, sir. So it is not valid? Yeah, I think, sir, your audio is on. So now we know the problem. The problem is that we are picking up so many cystic lesions, calling them as suspicious, but most of them end up either being benign or we are treating clinically insignificant cystic RCCs. So which means that the sensitivity is very high here, but specificity is low. So in order to fix that, the new version fixes the new version focuses on these things to reduce the sensitivity a little bit but increase the specificity. So you are going to be calling back or calling those lesions as three and four, which are definitely going to be clinically significant RCCs. So for example, if you look at this actual post-contrast image here, there is this five millimeter convex protrusion within this cystic mass in the right kidney. Again, this is from the same article which we'll be discussing today. According to the older lexicon and nomenclature, this may have been classified as Bosnian four, but with the new guidelines which we have in place or the new nomenclature, this will be Bosnian three. So you see the difference here. The drive is to minimize calling more and more lesions as suspicious and following up more and more lesions to make sure that you are not treating clinically insignificant cystic RCCs. So the learning objectives of this paper, it focuses on three main things. So number one, it is just pay attention to all the updates and rationale why this 2019 version of Bosnia classification was developed. So as you are aware that in 1986, the first version was kind of tabulated in terms of Bosnia classification. In 2012, it received a minor update and in 2019 it was completely redesigned. And that's the one which we're going to look at today. When and how to use these various modalities and when and how to apply Bosnia classification is something which we're going to discuss today. So as you can see, CTMR will always score high in terms of these Bosnia classification systems, whereas ultrasound may not be able to detect all the features described in the lexicon of Bosnia 2019. And that's why most of the times it will be limited to assessment of one or two lesions, not beyond that point because beyond that point you need to assess enhancement and multiple other intrinsic features which may be beyond the spatial resolution of ultrasound. Then the third and most important thing is to pay attention to lexical. Why is it important because this improves interreader agreement so for example if I'm calling something as Bosnia 4 by going through the lexicon terminology which are designed by this classification system. The likelihood of someone else calling it as Bosnia 4 is also high if that person also sticks to the same lexicon terminologies. The advantage of that is it has better patient outcome because of reduced interreader, interreader variability. And then, so what happened was that with the older version of Bosnia, they found in that systematic review from 2017 that there was a significant range or a very large range of disagreement between multiple readers. And that number ranged from 6% to 75% and this was particularly notable in Bosnia 2, 2F and three category masses. So 6 to 75% is a very large variation for any classification system and it's basically it makes a night and day difference for patient management. And then the other thing which we already discussed that there was a large proportion of benign lesions which were being excised in Bosnia 3 and 4. That's the reason why this entire thing was changed. So there are multiple teaching points within this paper which were described by the authors. So number one is cystic masses are the ones which are by definition containing less than 25% of enhancing solid components. So again, you're not supposed to be measuring these things, but it's a visual assessment that the lesion should contain less than 25% of enhancing solid component then only you can call them a cystic. Beyond this point, they fall out of the category of cystic masses. Then for category 2F or higher, we need to have at least some form of enhancement. And this is why ultrasound may not be the right modality unless you have contrast and ultrasound. But again, in the in the current lexicon there is no room for CEUS, but moving forward that is something which can be incorporated. But because of this right now we will be focusing more on CT and MR. There is only one exception to this rule. There can be non-enhancing cystic masses which have heterogeneous bright signal on T1 weighted fat suppressed image. However, it does not enhance. Those lesions can fall under the category of 2F. But if it is homogeneous and smooth and it shows bright signal, it falls into 2 and not 2F. Then what is nodule or irregularity and how to measure it? So this is something which is really important. How to measure it? Because there are so many important measurements in this lexicon that you have to make sure that you're measuring these lesions properly. So it has to be measured perpendicular to but not including the wall or septa. So what does this mean? It means that you will be looking at a lesion's kind of septation and then there is a bump or that convex protrusion on top of it. Exclude the sept out of measurement. That is when you will get the accurate measurement. That's why you need very high special resolution CT and MR exams. Then other measurement guidelines which are something which you should remember that avoid using T2s for measuring these lesions because it can exaggerate the size of the lesion or thickness of septations due to debris or hemorrhagic material. Ideally it should be done on the post-contrast sequences on CT or MR. If there are more than one Bosnia categories for that patient because there are multiple lesions or maybe a single lesion has different areas which appear differently, always choose the worst category because that dictates patient management. And most importantly, do not apply these categories or these guidelines in patients who have hereditary cancer syndrome, such as Vanipa-Lindau's Lynch syndrome, Burthog-Dubay syndromes. These are the patients who have a very, very high proportion of cystic RCCs as compared to other cystic benign lesions is because of the in-phase propensity to have RCCs. So these guidelines will not apply over there. In terms of imaging techniques, so this is just a case example shared by the authors. In terms of CT, you need to have a typical unenhanced then your nephrographic phase as well as cortical medullary phase. It is very important to follow these guidelines to make sure that you are assessing the enhancement of the lesions correctly. I mean obviously you will be asked these questions in your exams. You may have a question about assessment of renal masses in your residency exams or board exams. You will have to write about all these protocols on CT and MR both. Some quick reference tools are obviously you can go to Radiology Assistant or some other websites and you will definitely find a really nice graphic depiction of how these different phases make different things appear more obviously in the kidneys. So in this particular case on the unenhanced phase, the authors show here that the lesion measured about 7-hounds per unit. Then after administering contrast, there is just enhancement in the periphery of the lesion which measures up to 32-34-hounds per unit. The center is largely unenhanced and the enhancement further increases on the subsequent nephrographic phase and the center shows no enhancement. So this is nothing but a case where there is a central necrotic component within a lesion and this patient ended up undergoing a surgery and this turned out to be necrotic papillary RCC which was typed in this 70-odd year old individual. So just to show you the importance of multiple phases when you are performing renal mass CT. Then what is the importance of MRI? So for most of the parts CT or MR may be interchangeable in terms of assessing this cystic renal lesions. However, there are certain areas where MR definitely excels over CT. For example, in this case the authors show a patient with a large mass in the right kidney which is largely calcified. So on CT it is going to be very, very hard to assess whether that lesion is enhancing or not. And the only way to know that is that you will have to undergo a contrast enhance MR examination which has fairly low sensitivity for detecting calcium, but it has very high sensitivity for detecting enhancement. So with this actual T1 post-contrast image, you definitely see that there is this thin kind of septal enhancement which is occurring in this patient. This was essentially ultimately classified as Bosnian 3 mass because this was almost up to 3 millimeter size in terms of wall thickness as well as the septation thickness. So this is an area where MR comes into come into picture. The other would be hemorrhagic or hypotenous lesions. Again, in those cases MR may be used to perform subtraction imaging where the bright T1 signal is completely, it goes away and all you will see is enhancement. The authors also recommend use of this online calculator. So if you have your smartphone, you can just open the camera, scan this QR code, it will take you to this calculator and this is based on an algorithm which I'm going to show you later on in this paper. That you can just pick those options and you will get your Bosnia category for cystic renal mass which you're assessing. So this is the QR code for this, for this webpage or a calculator. They also have an app. I never tried downloading that but again they also have an app which you can use on your smartphones. So now lexicon is something which is most important in this classification because they changed the meaning as well as details and added a few more words in terms of how lesions are described. So these four are the most important things. Again, a beautiful graphic representation of different aspects of assessing cystic renal masses. This was initially published here in this paper I have given a reference here below and this was the original paper where it cited the need to change or update into Bosnia 2019. So what do you have to look for when you start looking at a cystic mass start with the wall first go from go from pay for the center so if you start from the wall. Again sorry for this thing but it's it's one millimeter here, if it becomes more thicker it'll be two millimeters then three and four, so you have to assess the wall thickness. Then the next thing, if it has separations you have to assess the thickness of the sector, the three most important numbers here are two, three and four millimeters so these numbers are really really important. Then, the next category here which you should remember are these convex protrusions. So these protrusions can be present on the cyst wall itself, or they can be present on the separations. So when they're present on the separations and present only on one side like in this case, all you have to measure is maximum perpendicular distance of the top of this protrusion going to the septum separation but don't include separation in your measurement. And if it happens that there are these protrusions on both sides of the sector, you have to calculate a combined distance or combined perpendicular height by excluding the sector that will give you the maximum size of those convex protrusions. The most important thing if you look at these blue colored convex protrusions as it is outlined by these authors, they have these nice obtuse angles with the separations as well as with the cyst wall. The next category to remember if you look at these orange or dark kind of amber colored convex protrusions, they have acute angle with either the cyst wall or with the separations. When that happens, size of the convex protrusion does not matter and it naturally puts it into category four. But if it is category three, then you have to measure the size of these convex protrusions and we're going to come to that when we are discussing category three lesions. So with this in mind, the authors gave some amazing examples of different Bosnian category lesions. So let's go through them now. So Bosnia category one. So these are essentially all benign simple cystic lesions, which you will pick up so many times when you're doing your CT examinations. So what is the hallmark of these lesions? For example, this case here, which is shared by the authors of this paper. The wall thickness is almost around just one millimeter, which is something which you expect in these benign cysts. So this is the left cystic lesion, which was obviously incidentally discovered. The Honsfield unit is only two Honsfield units on this incidental exam. It's kind of an it's a cortical medullary phase at the time of acquisition. The arrow shows that the lesion does not show any enhancement. There are no separations and there is no enhancement of the wall. There are no convex protrusions and there are no separations or calcifications in the lesion. So this will be a typical Bosnia one, Bosnia category one cyst. So now let's look at Bosnia category two cystic remasses. So this is a bit of an interesting category and needs a lot of attention. So in this case, the authors share an actual CT examination as well as an actual MRI both are post contrast imaging so remember you need that to make sure that whether it is a two or two F, you will not be able to figure that out if you don't give contrast. So in this case, this is a 45 year old woman, and these are actual contest enhanced images obtained during nephrographic phase. The lesion itself is three to four centimeter in size, and it has smooth enhancing thin wall so remember this is about one millimeter in size, the wall thickness is around one millimeter in size. It has at least two thin separations which are shown in these images and the thickness of the separation is up to two millimeters. There is a nodular calcification which is shown here with this arrowhead, but the mass showed no change over a period of five years they had serial quality of this patient. So this cystic mass which has 10 separations remember 10 is less than or equal to two millimeters, and only few sector which is only one to three but not more than three. These are the cysts which get classified as Bosnia type two. These are the different CT descriptors or CT findings which can be seen on Bosnia two legions so there are six different varieties or types of Bosnia two legions described on CT. These are evaluated on cross sectional imaging and these are the categories. So number one cystic mass with up to two millimeter thickness and few at least one to three sector but not more than that. The septa and wall may enhance and they may have calcifications of any type but remember they don't have convex protrusions and the sector are not more than three number, and they are not more than two millimeter in thickness these are the, these are the hallmarks needed for Bosnia two. In terms of homogeneous hyper attenuation on CT, they can be more than 70 ounce bill units which is essentially means that they are either hemorrhagic or hyproponitious, and they are. They can be detected easily at non contrast image you don't need to do anything further in this case. However, authors describe the need to recommend an MR if the lesion itself is more than three centimeters because it can have intrinsic heterogeneity which may be easily missed on the CT. Then category, the third variety under this category two legions are homogeneous non enhancing masses which are more than 20 ounce bill units at renal mass protocol, and they may have calcifications of any type. So now the problem is here is that you need to have a good spatial resolution to measure the cystic lesion sounds field units, and then homogenous masses which are between 9 to 20 on non contrast CT homogenous masses between 21 to 30 on photo in a space. These two categories number four and five will arise when you're reporting. CT examination which is done for some other indication, for example, acute abdominal pain rule out diverticulitis you do a CT and then you accidentally discovered a renal hypodense mass on a single port venous phase which is available, which is available to you. So now, even though the author has described the need to describe these lesions in much detail, we should also avoid any additional imaging if you can get more data or you can be more definitive on your amazing. So for example if you see a hypodense renal cystic mass, which is found on a non contrast CT and it has between nine minus nine to 20 ounce fill units, you can safely call it a Bosnian to on the other side if you see a lesion which is between 20 to 30 ounce fill units on photo venous phase. Again, you can probably call it as Bosnian to and move on again you have to make sure it is homogenous. If it is heterogeneous, you may be suspecting some internal convex protrusion. The last category is that they are homogenous low attenuation lesion, but they are too small to characterize. So I know there is a lot of word jargon here but some key points to remember, they should be well defined should have smooth walls, thin which is less than two millimeter wall thickness and only 123 SEPTA, which is again less than or equal to two millimeters but not more than that. So the challenge here can be seen with thick calcifications as we discussed earlier and that's the situation when you may need to recommend many many many to recommend a contrast MR examination. This is absence of enhancement so by definition absence of enhancement of administration of contrast is any change in CT ounce filled units between the pre and post contrast imaging specifically the nephrographic phase of only less than 10 ounce filled units that is when you can call it as absence of enhancement. So always remember that check the ounce filled units put the ROS correctly but make sure that it's not more than 10 ounce filled units, because if it is more than that we'll have to call it as enhancement less than that then you can just call it as absence of enhancement. Because as you're aware, there could be some intrinsic changes in CT density, even though the lesion is not enhancing. So let's look at these some important findings amongst these six types of CT variants of Bosnia too. So as we discussed, unenhanced CT these are two scenarios which you which you can find especially in the situations where patient is coming in with renal colic and all you do is just an unenhanced CT. So this image shows a bright lesion in the in the renal cortex, a really tiny homogeneous mass, which is around 76 ounce filaments as shows by shown by these authors, and the same thing here going on a single unenhanced phase left kidney actual image, a lesion, which is exophytic arising from the mid pole measures up to two ounce filaments. Both these categories can be safely classified as Bosnia to as per these recommendations. The next variant here which we see is a hypodense renal mass on a portal venous phase CT which was performed for a completely different indication. So let's discuss like for example rule out diverticulitis rule out appendicitis or rule of perforation and you accidentally see this, it falls within the permissible range of ounce filaments to call it as a Bosnia to solve this put your ROI to check how much it shows on the house field scale. The last variant, tiny hypodense lesion again accidentally discovered but too small to characterize again homogeneous, you can safely call it as Bosnia to. The next category Bosnia to button MRI. So why is it described separately because again you will you will have slightly more spatial resolution as well as increased detail of the lesion on MR examination as opposed to CT. So it has only two different description descriptors of categories under MRI. Let's look at one example here so this is a CT which shows a 36 ounce per unit mass on this cross section of the right kidney. It does show increased enhancement from 36 to 42. But remember that 36 to 42 is not more than 10 ounce filaments so technically you can call it as absence of enhancement. And then this is a T1 weighted image on the C1 very much all you see is a bright homogeneous T1 signal. So this is smooth or homogeneous T1 hyper intensity on T1 fat suppressed image. This will be called as a Bosnia to if this was heterogeneous, you could have called that as Bosnia to F, even if there is no enhancement in this lesion as per the only exception available in Bosnia to F category. So the most important question which sometimes you will be asked on your cases or you will you will just come across that when you're reporting how to how to assess it. Because sometimes it will not be as obvious as this case as as this that's how that happens with smaller lesions. So put your ROI into this lesion and get the get the pixel value at that at that level and put an ROI in the adjacent So the difference between these intensity should be at least better than 2.5 times. So which means that if you put an ROI here in the cortex and say it is like 33.5. If that's the number which is giving here, then on this lesion it should be at least 2.5 times more than that only then you can call it as a hyper intense lesion. So now, as we discussed on Bosnia MR category two, they have described only three variants. I'm not going to much of these details but always make sure that we check the P2 signal by comparing it with CSF, and always check the P1 signal on fat suppressed image by checking it with an ROI placed on the renal cortex. Let's go to to F the category which always has a lot of challenges and the reason why is that if you remember on from some of our initial slides. That on the systematic review which was performed at 2070 amongst the published literature, there were around 17% cancers amongst the resected Bosnia to F lesions. So that's why there's a lot of heterogeneity in this class, it's a continuum of lots of benign and cystic RCC lesions. So let's look at this image which is shared by the author. So always remember, you need to have the enhancement portion inside in place to call something as to F except for one thing which we already discussed. So this is an actual contrast enhance CT image, which shows that there is a cystic lesion in the interpole of the left kidney on this transverse image. There are separations within this lesion, the separations themselves are up to one millimeters in in thickness. And then what is happening here is that the lesion is about 3.3 centimeter, but there are many of such separations that have to be more than four, category two, they were only one to three, whereas in to F, they are more than or equal to four, but they have to be smooth and thin. So the thickness of the separations cannot exceed two millimeters in Bosnia to F category. Again, they have to be enhancing. In this case, the authors have data for around seven years for this patient. So it did not change over those seven years, but once in a while you will have a case where we call something as to F and that's the whole point you call it as to F. If you follow up examination, certain things will change in that lesion, you will see a new convex protrusion, increased thickness of separation changes in the walls, and that is when you will have to bump up the category from to F to either three or four, depending on what you see. The next variant in this category to F on CT is this. So now what is happening in this case, you have only one smooth sceptre, but that sceptre is minimally thickened which means that it is three millimeters. If you have one sceptre in the lesion, which is enhancing and three millimeters in thickness again that can be called as Bosnia to F. However, in even in this patient, there was no significant interval change for five years so the author have data of five years to show that this lesion did not change, and both of these were category to F lesions which showed long term stability. So what are the features of Bosnia to F number one, that the lesion should have a smooth but minimally thickened wall which can be up to three millimeters. Then they may have enhancing wall again that is something which may be expected. It can have smooth minimal thickening of one or more of the enhancing sceptre, or they can have many sceptre, which can be 10. However, if the sceptre are up to up to up to three, and they are up to three millimeter in thickness, it can be category to F, but if there are more than four sceptre then they cannot be as thick as three millimeters they have to be only up to two millimeters. So that's the that's something which you have to remember when you're assessing these lesions. Again, this is something which we are going to vary in integrity, but the reason why all of these. descriptors were put into place was because of the fact that there were too many cystic lesions which were being either biopsied or resected which did not turn out to be carcinomas. So I can see some some raised hands here so maybe let's check if maybe let's check if I can answer the questions for the time being. One question in the Q&A from Dr. Akshit Bharadwaj. How to call it a solid component. Let me check. Okay, can you read the question because I just see chat section I'm not able to see the Q&A. How to quantify the percentage of solid component. Right. So that's a good question. So as we discussed earlier, it is a visual assessment. So you don't have to measure anything, but visually you have to make an assessment that okay is this approximately 25% of the lesion or not. If it definitely feels more than that you cannot apply Bosnia classification because the odds of that lesion being a cystic RCC. Or for that matter, a cystic lesion of benign potential are very very low now you're definitely dealing with something which is more sinister, and maybe it will go into turn out to be a malignant lesion. I think there's there are a couple of attendees who have raised hand go we I don't know how to how to get those details. Can you I think Ibrahim was raising the hand maybe you can post your question in in Q&A section if that's okay with you. Thank you, Ibrahim. Well, I'm sorry, I think it's. If you have any queries you can just post them in the either in the chat box or in the Q&A section and we'll get to those. There's. Yes. Yeah. So I'll wait for some questions coming up in the Q&A section and let's keep on moving for now but I have I hope that answers the question about percentage of solid component assessment it's a visual assessment it's not a. It's not what I can say it's not a strict guideline per se, but it's a visual assessment you have to just do an assessment and say okay this is 25 so for example like in this lesion. This is definitely not 25%, but in some of the cases which I had in the, in the, in the initial quiz, they were definitely greater than 25%. So, let's look at the Bosnia category to f MRI. This is again something which is challenging and something which you may come across because they already did an ultrasound. They didn't, they did a city, and they were still not able to sort out the problem of assessing cystic lesion and maybe because of the fact that the lesion had hyper dense contents and that's why they landed into trouble. So in those situations you will see a bright lesion in the renal cortex this is an actual even weighted unenhanced image. All you can see it just this bright lesion in the renal cortex which means that it's definitely going to have some kind of hemorrhagic or hypotenetist contents. So the authors are showing this case, just to show an example of category to f MRI. So now you administer intravenous contrast. So, as expected, you hardly notice any significant change here in the enhancement, but these exams are quite apart from each other. So the patient was on follow up and this is an examination which is performed at a later date. So the examination, so the lesion itself has enlarged in size. And an administration of contrast it was very difficult to assess whether there's enhancement or not. So that's why you need your subtracted images to show if there is true enhancement with the lesion. So in this case what is happening is that on this fat subtracted fat suppress subtracted MRI image in the nephrographic phase, you do not see any internal enhancement. So the arrow shows that the sister does not show any internal enhancement. So this is something which is really typical of these bright even lesions you definitely need the subtracted image to show if there is any enhancement or not. So this is something which is really important between category to and category to have. So what are the cystic masses that are heterogeneously hyper intense on non contrast image. So if you look at this T1, they definitely show some intrinsic changes as opposed to. Let's go back to the previous case which we saw as opposed to this case. So look at how homogenous this lesion appears. So this is category to however in this case, which we're looking at right now. The lesion is heterogeneous on T1 with an imaging. So that's why it will fall under the category of category to F something to always remember as a corollary to this Bosnia category to F. You should always assess these bright T1 lesions very carefully. Let's look at that in terms of an example which is shared by the authors here. So this was a lesion. I mean, you can ignore the heading here. I'm just explaining you why is it important to look at the enhancement. But the authors have shared a case of a patient who who is a prostate cancer survivor. And on one of the follow up examinations they found a new hyper dense cystic lesion in one of the kidneys. So it was a right renal upper pole so I'm just showing the authors have just shared the image which shows the lesion. So I'm not sure how the numbers are seen on your screen but basically they were not really sure if there's equivocal enhancement or not. So they wanted to do an MRI. So on MRI, definitely you have this T1 in phase and out of phase. So all of the residents who are attending today's session, this is something which will be asking your examinations about T1, like in and out of phase imaging. And also again the patient underwent a full gamut of MR examination. So on that examination it persisted it showed bright appearance and something which is in keeping with hemorrhagic contents. The only problem was that on the non subtracted images this is actual T1 without and with contrast visual assessment was quite difficult. It was really hard to separate these lesions from one another, especially to say if there's enhancement or not. When we put these ROIs, if you pay close attention along the posterior as per the lesion, you get an ROI measurement of 74 and then on post contrast it increases to 99. So there is actually an enhancement within this lesion. So even if it is heterogeneously T1 bright on an enhanced phase, now it is showing enhancement, so which will bump it up from category 2F to category 3. So note that if no enhancing features had been identified in this case, this would have been classified as 2F, but because there are enhancing components, this will be bumped up to category 3. So always pay close attention to these lesions while you're doing your MR exams. Now let's talk about category 3 lesions. These are the ones where we start to think more about carcinomas, especially the cystic RCCs, because as you remember we are dealing with cystic renal masses. So this is an example which is shared by the authors of a category 3 lesion where you have this cross section of the right kidney. This is an actual acquisition post contrast even fat suppressed image. All you see is a 2.1 centimeter cystic renal mass with enhancing thick 5 millimeter septa. So this is nothing but a single kind of septation here, but it is 5 millimeter. So the previous separations which we discussed about, they were all 2 and 3 millimeters in category 2, category 2F, but now this one is 5 millimeters or more than 3, that puts it into category 3. This was at excision turned out to be a grade 2 clear renal cell carcinoma. The next example which they have shared it's a different patient, left renal cystic mass actually even post contrast image. And you can appreciate that this is subtraction as a lot of surrounding tissue is all completely, it's all subtracted. All you see here is on this portal vein portal in the space that there is a thick enhancing wall, and this wall measures up to 7 millimeters. So again, this is Bosnia category 3 turned out to be a grade 2 clear cell RCC. There are more examples which are shared by the authors. So here what we see is that this is an unenhanced and enhanced image of the same patient of the left kidney, where you see a large cystic left renal mass on excision obviously it was grade 2 cystic clear cell RCC. But what makes it worrisome on MRI is that on this T2 weather imaging you see this small papillary projection on this on the surface of this wall here, which measures, which kind of shows obtuse angle. So if you look at this post contrast image, even though it is only 2 millimeters, it kind of shows these obtuse angles that's why the patient underwent the section, and then ultimately it turned out to be an RCC. So the key point here is you will need to assist these spots in multi planner reconstruction to exactly get a sense of what is happening with those lesions. So that was irregular wall that's why it was excised so let's move on to Bosnia type for again a case which is shared by the authors here. So the white arrow shows the cystic component and the red arrow shows the convex protrusion or nodule within this lesion here. So now this is what is happening in this patient, then you also have another case here where you see that there is this four millimeter post contrast enhancement. There's four lesions why because these obtuse these convex protrusions have obtuse angles with the cyst wall so that bumps up into category four. So again this turned out to be a grade two clear cell RCC patient underwent partial nephrectomy. Next example here is a mass in the in the right kidney in the intra polar region again you see that there is there is a cystic mass here. On one of the walls you see this large kind of solid component, it is measuring up to six millimeters in thickness in this patient. So this patient underwent partial nephrectomy again, it turned out to be a grade three clear cell RCC. So what is what are the key points here, you definitely see that these category four lesions will have enhancing nodules, and the nodules are a feature of Bosnia for cystic masses. They may have obtuse margins, the nodules may be more than or equal to four millimeter in size, or they can have acute margins when the nodules can be of any size when in the in the first case, the nodule irrespective of the size it has these acute angles so I'm really sorry if I said obtuse here, but I meant to say acute angles with the nodules so shows any acute angles with the walls, this will be Bosnia category four irrespective of the size of that nodule. And again, make sure that you're measuring the nodules on contrast Nance image and not on T2, because this entire thing may be comprised of the the enhancing solid component, as well as some aggregates of hemorrhagic material debris which is sitting on top of that nodule. So measured on the post contrast phase and not the T2 image, because you may exaggerate the size of the nodule. So before we move on to the next section of this paper, the most important conclusions based on what we saw till now. Number one, for those studies are still needed to assess what is the impact of changing the classification system on patient management. However, I showed you one slide where we are seeing increased number of detected RCCs, but no significant change in patient mortality, as well as metastasis. So we need to see how much impact we have made by introducing this new 2019 version of Bosnia. The second point is what the shortcomings of previous version are addressed or not. So what were the shortcomings, large variability in terms of agreement. Lots of benign lesions excise them as category three and four through some of the some of the challenges which we faced in the previous version so we have to check if those are in or are improved or not. In the future, there should be a way to incorporate contrast and ultrasound in this gamut of tests because as you're aware, not all patients will be able to get contrast on CT or MR, depending on their renal function status. Then we move on to the next section of this paper, which is probably the most important again. That is a nice flowchart as to how to assess this renal mass protocol CT images and how to assign different categories to these lesions. So again, it's a very busy kind of a diagram, but you can go to this article and go through these flowchart on your own, or you can probably also just use the online calculator. It uses the same algorithm. But always remember the areas which we want to focus on is that number one unit to ensure that do we have a renal mass CT protocol or not. If you don't have a renal mass CT protocol. The only the only areas where you can make a difference is calling certain lesions as category one or category two. Anything more than that you will need a renal mass CT protocol. And once you have that you have to assess for all the different categories or lexicon terminologies which we looked at convex protrusions obtuse margins or not. What is the thickness of the SEPTA how many SEPTA how is the wall like, are there any convex protrusions on the wall or on the SEPTA if they are there. How big do they measure all of those things will help you pick one of these Bosnia categories and the only other thing to remember that you may land into trouble with certain lesions will not be classified on CT. That is when you should understand that you have to recommend an MR to these patients. The second flow chart, which which we are discussing in this in this article is about MR. Again, they have gone through a very nice algorithmic approach in terms of assessing renal masses on contrast enhance MR examinations. So again, we have to focus if a renal mass protocol was done or not, because sometimes you may have a patient who is just coming to you for routine follow up of IPM and you did not even give contrast to that patient. And then you accidentally notice a new renal lesion. So again, that's really important but again, most important thing is if it was a renal mass protocol that is where you have to figure out how you can classify the lesion amongst all the categories of Bosnia classes one, two, two F, two F, I mean, category three and four. Remember that you will be making a difference in the in the patients who have a large chunky calcification on the cyst wall. And they are not able to tell on CT whether it's a category two F or category three. Those are the patients which will definitely benefit from MR because you will be able to see there's enhancement or not. Otherwise, you will follow all the typical features of Bosnia three and four to ensure that they are suspicious or not. The next important thing is that the authors also discuss use of a template for reporting so if you're if you're not aware of this, you can always go to write report that website has a ton of templates which you can freely use and use for reporting, or you can create your own reports. But at the end of this report when you're assessing cystic mass, the authors recommend you can use this table as you use it and say tyrants or overrads or byrads that you give a risk assessment category and what are the recommendations and based on that you can also recommend the same thing in your report. Remember to describe the side size, go for the separations enhancement. And then you have to look for convex protrusions and then describe each and every category in terms of category wise recommendations, obviously category one and two, they don't need any specific follow their benign. Two F is the area where you will have to do some kind of recommendation. So the large majority of these will be benign, but when malignant nearly all are usually in Dolan so these, there could be a small proportion of cystic RCCs which will be categorized as two F, but the goal is to prevent over treatment of certain amount of cystic RCCs based on the data that we have. So generally, Bosnia two F masses are followed by imaging at six months and 12 months and then annually for total of five years to assess for any morphologic change in between. So if you're if you're doing baseline, you recommend a six month follow up, and then you can recommend 12 and then every one year they can be followed up, rather than having to undergo a really, really invasive nephrectomy or partial nephrectomy. Then Bosnia three masses have an intermediate probability of being malignant. So if they have not obtained, they should consider seeking a urology consultation they may decide whether they want to biopsy lesion or excise it up front if the patient has other high risk things going on. Category four, largest majority of these will turn out to be malignant and if they have not already seen a urology they need to go and see urologist to see if they want to undergo a surgery, what kind of surgery and when. So now with this in mind, let's go and look at one case which I have added here as an example, just to see how well we do in assigning Bosnia category now that we have knowledge of these different lexicon terminologies. So these are just some actual images of the right kidney in a patient who had this discovered incidentally. So we did a complete renal mass protocol. So we have an actual T2 fat suppressed T1 pre contrast lava, lava is nothing but lava vibrant everything is just basically just takes an amazing technique. Then we have T1 weighted water, lava, arterial phase, and then portal venous phase. So now the arrows are showing the renal mass. All we see is that the lesion is a 1.3 centimeter cystic mass without significant wall thickening and multiple more than or equal to four smooth 10 septa less than or equal to two millimeters on the arterial and portal venous phase. And it has no convex proportions. Again, the patient was just being on surveillance because this was incidentally detected at the time of previous septal cancer resection. So we have been following this up and it has not changed much till now for the last couple of years. So based on these categories or these descriptor remain remember we have four or more septa and the septa measure up to two millimeters in thickness. So then now what Bosnia category we can assign to this lesion so just think in your mind, whether it's category one, two F four or category two. So definitely we have to make sure that in this case we assign a category two F based on the on the classification parameters which we have. So this patient had category two of lesion. Again, Bosnia category two of lesions can be followed up at six months 12 months then annually for a total of five years to assess for morphologic change. And again, a quick quick kind of repeat assessment of the same areas in category two F you may have more than four septations but they are thin. So the septa are only up to two millimeters in thickness and they don't have any of the convex protrusions on them, and they will show enhancement. So again, this is this is probably the most important diagram in the original 2019 update paper which was described. Obviously, you're going to recommend the follow up so in this patient what ended up happening was that on follow up the lesion decided to change your small apology. And then three years later, now we start to see new enhancing nodules or convex protrusions, and some of these areas were showing obtuse angles with the with assist wall, but the height or the perpendicular height of these were was greater than four millimeters. So now this got upgraded from Bosnia to F the Bosnia category four. Ultimately, it turned out to be an RCC on excision. So remember to use your category to F judiciously remember that they are going to be some cancers amongst them but the goal is to catch the cancers which will impact, which will impact the patients long term survival and not the ones which will be indolent as it has been showed on multiple previous population base series. So now with this let's go back, let's, we're almost at the end of our hour so let's go back to the quiz questions which we looked at at the beginning of this session. So the first question was that when will you use Bosnia classification. So case number one, there's definitely you see that there's this tiny eccentric convex protrusion, which is not typically cystic. This is the schedule we have the kidney on CT examination. So this mass is largely largely cystic so just go ahead, you can go ahead and answer again. The second least the second case is here is again a case which shows a large solid component here. And again case three shows a large solid component. So what do you think I'm getting very good answers here case number one most of your going for case number one, and that's exactly what it is. When you release Bosnia calcification classification because it has lesser than 25% of solid component. So excellent. Everybody has done a good job at this question. Let's, let's go to the next question which was the second slide. Again, when will you use Bosnia to F or higher. So we have case number one, which is a sagittal ultrasound which shows a cystic mass in the lower pole of the kidney. actual P2 imaging which shows this high signal intensity mass in the interpolar region of the kidney. And third one is a post contrast image which shows smooth and thin enhancing separations. So, yeah, so most of you are answering correctly. Yes, so that's that's really nice. So let's, let's show you the answer so again as expected case number three. Why, because you need a post contrast image to assess if it is Bosnia category to F or higher. So that's why first case is an ultrasound, you cannot comment if there is enhancing separations actual P2 weighted image you cannot comment if there are enhancing separations or wall, or any convex protrusions. So first contrast actual MR where you can definitely comment on these separations and in this case as we looked at it earlier. This was a category to F itself. So I am at the end of the presentation here so if you have any questions about this presentation you can always reach out to me. Now you can type any questions in the chat section, and make sure that for those of you who have a radiographics or RSNA membership to go on this, this portion of SACME credits for this article, you can access this article for free. You can complete those credits and you can get credits, because since you spend all this time to understand the paper. If you have other things which are discussed in the paper I did not go into a lot of those I touched upon all the basics or important portions which they have discussed. So make sure that you make the use of your RSNA membership to get, get the credits on this article. I can stop sharing my screen. And let's see if there are any questions. Thank you Amir. That was really excellent. I mean it took us through it beautifully. Really simplified the article I'm sure they must have really loved it. There is one question from Akshit again. So can you repeat the exceptions to to F. Good question Akshit. Always remember that there is one exception for category to F. And that is only when. So the general rule is that you need to see enhancement. That is when you can start calling something as category to F. But the only time it can cause something as to F when it is not enhancing. And that is basically a situation when you have heterogeneous T1 hyper intense contents in a cystic renal mass, but it does not show any enhancement. So if you have a T1 bright lesion, which is homogeneous and non enhancing, it is too. But if you have a T1 bright lesion, it is heterogeneous and non enhancing category to F. So that's the only exception for to F where you can call something as to F, even if it is non enhancing. So I hope I answer. Yeah, so I hope I answer that question. Yeah, there are no more questions as such but you can always reach out to me or any of us if you have any queries, maybe later as well should be I think for a couple of minutes just to see if anybody wants to post something. Yeah, I'm just leaving my email address in the comments if anybody wants to get back to me later on. So you can always reach out to me. Thank you. Do let us know your suggestions as well if you want us to alter the format a bit, maybe include anything else. If you all want to participate as in if you all want to discuss cases, or maybe be a part of the article discussion as well suggest some articles we could do that as well. Also, we could alter the format in such a way where we could discuss topics or tips for writing articles, how to choose your topics, how to get things published, certain tips and tricks from our experts as well I mean would you like to add on to that. There was a query where somebody had asked if we could discuss the article writing Percy. Yeah, that's a that's a very good question that is something which everybody struggles at. So the only important thing which I spent a lot of time in my fellowship here here in Canada was number one is obviously you need, you need to have first is motivation you need to have motivation to write something. Because it is always like you will always find these amazing people who are writing day in and day out and it's just rewarding to them so they'll keep on writing. The number two is that you need to have really good collaboration, especially if you're starting early on, you need to have good collaborators because they are the ones who are going to guide you through the process. You may not know a lot of things in terms of people writing like, for example, how to ensure that you are awarding any plagiarism issues how to avoid duplication of work. You should know the basics of statistics because then when you reach out to epidermal epidemiologist, you should reach out to them with some kind of solutions or answers. So, at least one thing which I can definitely recommend if somebody is starting to write their residency dissertation, let's say if you're writing your residency dissertation. And if you have questions about the methodology part where you don't know what kind of statistical test you want to apply. There is one really good article by radio graphics it's called a statistics one or one for radiologists. I use it all the time because I'm completely untrained in epidemiology. So I use it all the time when I'm when I'm struggling as to okay what how I should apply like how I should go about the data which I have. And that also gives you idea to think about how you want to design your studies. So again it takes very long for some research studies which even if they're cross section they can take really long because of the data acquisition process. So as soon as it is done, just start writing your paper, go to some real good quality research, which is similar to your paper, and get some ideas to how those authors approach the question at hand. That always helps. But I think I think it's a, it's an important. It's an important discussion. But again, you have to start writing. So definitely take that up maybe in one of our future programs we could include a discussion just on that. So, thank you, and thank you for whoever sent that query. I think right now it's just compliments for you, no more questions coming up. Thank you for an excellent lecture and people are thanking you so thank you so much I mean I think we can wrap it up. And thanks once again for joining us on a Sunday, and for that excellent discussion. Thank you everyone who's joined in who's doing on a Sunday morning for this radiology journal club on body imaging. We have more such coming up in the future as well. Please do join us for the upcoming journal clubs we will let you all know what topics and the systems that we'll be covering the next month and the one after that. So today we had body imaging with Dr. Amir Kulkarni. I would once again like to thank our educational partners bears and phantom healthcare for their support. And thank you to the entire organizing team at Indian radiologist and all my team members. Amir Kulkarni thanks once again. And once again I would just like to remind you all about Sonobahs which is in Jan on the eighth and ninth in Mumbai it's a hybrid event will be online as well as on site. So please do register for the same send us your paper and poster entries, and even send us your images for the PTVs contest. Thank you for joining in. Take care and see you all next month. Bye bye. 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