Normal and Abnormal MRI Appearance of the Pediatric Bone Marrow | Dr. Alejandra Bedoya

Hello and welcome to noon conference hosted by modality. Noon conference connects the global radiology community through free live educational webinars that are accessible for all and is an opportunity to learn alongside top radiologists from around the world. Today we are honored to welcome Dr. Alejandra Bedoya for a lecture entitled normal and abnormal MRI appearance of the pediatric bone marrow. Dr. Dr. Vedora completed her radiology residency and MSK subsp specialty training at the University of Pennsylvania. She did her pediatric radiology and feder fetal subsp specialty training at Boston Children's Hospital Harvard Medical School where she stayed as faculty for four years. Currently, she is a pediatric radiologist at Sick Kids University of Toronto. At the end of the lecture, please join her in a Q&A session where she will address questions you may have on today's topic. Please remember to use that Q&A feature to submit your questions so we can get to as many as we can before our time is up. With that, we're ready to begin today's lecture. Dr. Bedoya, please take it from here. Thank you so much, Ashley, and thank you so much for the invitation. It's a great pleasure to be here today talking about normal and abnormal bone marrow assessment in children. I don't have anything to disclose. So we're going to start with a case um that this was a case that I had during fellowship and I think it describes why this topic is is so important. So we have a four-year-old male that was transferred from another country with the diagnosis of severe juvenile idiopathic arthritis anemia and subdural hematomas. So the history is kind of bizarre. Um we were consulted by rheumatology to review the prior studies and the history that we got this was an international transfer. The history that we got is that he had one year of fever generalized pain. He had a hip MRI. After that hip MRI he was started on prednisone and metrotex. He developed a piladema. He got a CT scan and six months later he had a forehead nodule and a neurosurgery was consulted. So the history is atypical. So these were the first radioraphs from 2019 and they were relatively normal like no focal anormality seen and this was the concurrent MRI that was performed at that time. So as I said this was one year before he presented to us. So we have a coronal T1 we have a coronal T2 fat side in two different sections and I want you to look at the images and think about what is the principal diagnosis in this MRI. So is it bilateral fusion is a septic arthritis of the right hip leftsided pericular myioitis or bone marrow infiltration. So I want you all at the end of this presentation to be confident 100% that this is bone marrow infiltration diffuse bone marrow infiltration. So h let's talk a little bit about what happened to this patient unfortunate case. So he had an an ultrasound of the bilateral knees and unfortunately this was also described as neopusion as I said we don't know as this is an international patient unfortunately based on the first MRI he was started on a steroids and prednisone this was the ultrasound of the knees and something was measured here and there was reported by lateral neusion but we need to remember that when we do ultrasounds in pediatric is different than adults Pediatric patients have a lot of epiphysial cartilage which is like this is an MRI of a similar age patient and you can see that the epiphysial cartilage is relatively big and on ultrasound the epiphysial cartilage looks completely anoic. How can we differentiate it from join fusion? The good thing is that ultrasound is a dynamic study. So we can do compression to see if the fluid moves. We can actually move the joint or the knee to see if this is actually fluid or if it's just the anchoric epithesial cartilage. But in this case you can see the normal femoral epiphyses. So this is like a longitudinal view of the knee. You can see the tibial epithesial cartilage the fises the epifyses and the metaphysis in this area. So unfortunately in this case there the important findings were missed. This is non neusion and unfortunately as I said this patient was started on premis. So we have CTS from September 2019 and June 2020 and on the subsequent on the last M CT from 2020. Unfortunately this was reported as subdural hematomas. But the truth is that the most important finding was missed and it was the model appearance of the bones. It looks really regular. looks really atypical and we can see these forehead nodules. So these are extra these are external. So this could not be a soft um subdural hematomas. These are actually extra oscio soft tissue masses. So when he presented to us on admission we can see that the radioraphs now are abnormal. There is diffuse a diffused like patchy maro infiltration process. We can actually see on the CT that there is uh mass in the left pelvic, the retroparitinal region at the succumb organ with a metastatic lesions in the bilateral superclavicular nodes and unfortunately I mean the whole bone marrow signal the whole bone appearance is abnormal and he develop AVMs of the proximal hummeral heads as well as the femoral heads. It's unclear if this is secondary to the primary disease or the high doses of steroids. So this case is actually a case of neuroblastoma. So he underwent an MIBG in our institution with the highest C score we have seen 29 over 30. So this MIBG scan looks like a bone scan [clears throat] but all these are just metastatic oious diseases. So the reason why I'm showing this case is because I think we can make the diagnosis with the first MRI and throughout this talk we're going to I'm going to give you tips of how to make the diagnosis confidently. So neuroblastoma in this case is responsible of 15% of cancer related to children death. So he was a fouryear-old. So every time we see a bone marrow infiltration process, we have to think about lymphopoliferative disorders such as leukemia or lymphoma and also neurolastoma which can have diffused bone marrow infiltration and it's a pretty common finding in children of diffuse metastatic disease. So let's start with the basics. What are the different types of bone marrow and why do we care about this? We care about this because children you're going to see the normal process of conversion from red marrow to yellow marrow throughout the skeleton. And we need to remember that hisystologically the red marrow is going to be the hyperscellular the one that is in charge of hematopoysis but we need to see and I'm highlighting this with a star is that it has 40% fat. So this is extremely important because the only role of MRI is differentiating between fat and water. So if we know that red marrow has 40% fat, we will be able to differentiate normal red marrow from muscle or from an bone marrow infiltrative process that is going to get rid of that fat. Of course, the yellow marrow or the fatty marrow is going to have 80% fat and is going to have a more nutritional support goal in the in the bone marrow with limited vascularity. So, we need to remember there are two types of red marrow and something important that we need to remember is that there is a normal bone marrow rec conversion which is the transformation from red marrow to yellow marrow. So this bone marrow conversion happens in a predicted way and you have to know it because an abnormality of this normal process is pathologic. So, so the first important rule is that the red marrow converts from distal to proximal and that's why the in the axial skeleton for example in the spine you can still see red marrow particularly in women because there is a higher need of hemopesis um and it's a normal finding to see a little bit of red marrow in the proximal femurss or in the pelvis or in the in the spine. So this is from distal to proxima but also there is a predictable bone marrow conversion within the long bone. So within the lung bone and I don't know if you can see my video but I always say that the bone marrow conversion is like epiphosis diaphysis metaphysis epipysis diaphysis metaphysis. So first is going to be the proximal epiphosis then the distal epiphosis then the diaphosis and finally the metaphysis with a little bit of residual red marrow in the proximal metaphysis. So why do we care about this? Because in a child you're going to have for example first the development of your distal aspect. So for example a neonate or a newborn is going to have your distal secondary center in the femur. but not the hummeral head the the the femoral head. So the first rule is predicted um conversion distal to proximal. The second rule is epis diaphysis metaphysis. And the third rule that is really important is that at the beginning of the um appearance of the secondary sification center in radioraphs you're going to have red marrow but after six months of the radiographic appearance that red marrow is going to turn into yellow marrow. So why do I say this is because each bone is going to have a different time where the secondary sification center is going to appear. H so for example in the femoral hair as we know h we do radio ultrasound assessment of the hips in patients younger than six months and usually after 6 months we do hip assessment for hip dysplasia with radioraphs because we have a secondaryification center in the femoral head. So at the beginning it's going to be yellow mar red maro and then six months later it should be um yellow marrow. So the best sequence to evaluate the maro is the t1 without a fats. So the routine T1. So if you are doing a pediatric msk protocol it should always have a T1 sequence. So why the T1 is so important? The T1 is important because the normal red marrow as you can see here for example in the proximal femur in a 5-year-old is going to have higher signal intensity than the adjacent muscle and this is the fifth rule because you're going to have 40% fat. So that's how you know you have a normal red marrow. So one is distribution and the other one is signal intensity. So here we can see with different age ranges how the normal bone marrow conversion happens. So it first happens in the knees compared to the to the hips. And you can see in a oneweek old how we pediatric radiologists we struggle to evaluate the marrow in neonates just because when they are born they don't follow the rules and they have so much red marrow and they need so much hematopesis that even your normal red marrow is going to be darker or in lower signal intensity than the adjacent muscle. And that's why it's so hard to identify osteomiitis in these babies. Her but after that it's really easy to differentiate what is red marrow and what is yellow marrow. So you can see that at the beginning you don't have a secondaryification center but then at one year of age you should have your normal femoral head with yellow marrow. This is an MRI of a fetus like a T15 and you can see how much yellow red marrow is in that diaphosis. This is the distal femoral epiphyses that is not oified actually like is like one little secondary oification center is forming and your femoral head is not oified but all this is just really dense hematopetic red marrow. So the signal intensity in the bone marrow is important as I as I just described and for me the T1 sequence is the most important. So the T2 sequence is going to help you to like your eyes are going to go to the normality like like high signal on T2. But the T1 is a sequence that is going to tell you if it's aggressive, non-aggressive or normal red marrow. So remember T1 red marrow when we compare to the muscle it should be equal or higher signal just because has 40% fat and the T2 is going to be bright and the red marrow usually enhances h the yellow marrow of course is going to have high signal on T1 low signal on T2 just because it has a higher fat component but as you can see the red marrow compared to pathologic infiltration and edema the T1 is going to give you the clue if it's normal or abnormal because edema and pathologic infiltration is going to have lower T1 signal when compared to the adjacent muscle. So a normal muscle should have 0% fat. So you should compare with a normal muscle and if you don't have for example in a spinal MRI where you don't have your muscle to be able to use as a comparison tool you're going to use the intervertebral disc as your normal as your um factor to decide if it's higher signal or lower signal but it should be higher signal. So chemical shift shift imaging is another tool that we can use to evaluate marrow signal and fat presence within the red marrow. So normal red marrow and yellow marrow should have drop of signal in the out of of of face just because of the microscopic fat. But the truth is that in tiny babies this is not going to be useful and I didn't use it um in in in neonates or younger kids because there is so much red marrow that is it's just not useful. So this is for example a neonate where the inphase signal actually looks that it has lower signal intensity than the out of phase that doesn't mean that it's abnormal. We just don't use this in pediatrics as much. So if we go back to the case one the case that started all this conversation and if we apply all the rules we can see how abnormal this first image is and you only need the T1 to make your diagnosis in this case. So for example as we said the human the femoral head should appear at 6 months of age. So that means that at one year of age you should have yellow marrow but we can see in this T1 that at four years of age this is not a normal fatty marrow within the hummeral head. So there is an abnormal distribution. And number two it's so dark like it's in some areas is lower signal intensity than the adjacent muscle. So we have an abnormality in the distribution and an abnormality in the sigma. And the problem is that in the T2 the bone marrow infiltration is so diffused that sometimes is easy to miss the the finding or sometimes it's easy for your eyes to go to more focal anormality. So for example here in the Iskum you can see that there is higher signal. There may be some petty articular like muscle edema but your eyes that's not the finding you know like and sometimes when there is so much bonar infiltration you see areas of necrosis or like AVM but that's not the diagnosis the diagnosis is not AVM the diagnosis is just diffused bone marrow infiltration so the T2 sometimes can be a little misleading so go to your T1 apply those rules and you won't miss any bone marrow infiltration process So let's look at this case. So this is 17 year old with shoulder instability. So if we apply the rules that is a little bit of like abnormal signal in the subcondrial region that is a little bit bright on the PD a little bit low signal on the T1 and but if you see it mirrors the bone marrow the normal red marrow in the metaphyses is low higher signal intensity than the adjacent muscle but it has an a relatively abnormal distribution is in the pipes like you shouldn't have at this age anything like red marrow that looks in the pipes. So [snorts] the question is like is it osteomiitis? Is it bone marrow infiltration? Is it a normal variant or subconia secondary to cartilage loss and with all the rules there are always exceptions. So this is actually a normal variant that we all need to identify so we don't call it abnormal. So it's really important when we evaluate red marrow in children how like there are some like normal variants and some of them can be for example flame shape you can see this metaphysical like flame shape red marrow signal abnormalities and but if you follow the rules it is like higher signal than the adjacent muscle it has normal distribution which is in the metaphysis the pimpes look normal is illdefined so that's a normal red marrow. You can also have marrow appearance particularly in the feet and the ankles. We don't know if this is just like red like clusters of red marrow particularly after you have a fracture you are immobilized you cannot like weightbear or if it's just like micro like micro um fractures within the the the bones. It's unclear. We believe that it's just a normal variant and you will see in our report that we sometimes don't even mention it because it's is so normal in kids. This is an example in the ankle where you can see all this like model appearance of patchy red marrow and this is completely normal. Another norma variant is the epiphysial ho and this is the example I gave in case two. We need to remember that it exists so we don't call it abnormal. So it the rules of this one is that it's per parallel to the is to the articular surface. We usually see it in the hip or the or the humorris or the shoulder. And if you see it follows the rules that is higher signal than the muscle is illdefined and it has to be parallel to the subcondrial bone. Another variant is the facial anchoring which is like these little lines that we see that there is not true like bone marma. We don't know if it is like just red marrow or if it's just like fibrous anchoring of the faces but this is not a phobi which is the focal um edema but if I see edema this is just a normal anchoring of the faces. So let's go to the case three. So this is a 16 year old with contraateral right femoral osteocaroma on chemotherapy. So all these two are T1 weighted images. This was in 2018 and this one was in 2019. And you can see that there has been a change in the bone marrow appearance. So on t on on 2018 at time of diagnosis we can see that there is normal red mar in the proximal femoral metaphysis which is normal in appearance but in 2019 it started to be too dark like too lower signal compared than the muscle and there is this abnormality in the pes and the diaph this is like abnormal. So the question is what can this be? Is this osteomiitis? Is this metastasis? We know that the patient has osteocaroma. Is this bone marrow recon conversion, osteotoma or stress changes. So in this case this is bone marrow recon conversion and we need to be familiar of what is bone marrow recon conversion. So bone marrow recon conversion is the opposite of what we discussed, right? The good news is that it happens in a reversible predictable pattern. So it's the completely the opposite of the conversion. So that means that if you your body needs more hematopogenesis. So for example you have anemia or you are on granulocytes stimulator factors um you on a like as part of your treatment the bone marrow is going to convert to red marrow. So that's what we call a recon conversion and it's going to happen in a reverse predictable process. So that means that first is going to be your metaphysis then it's going to be your diaphosis and finally your epiphosis with the axial skeleton happen first and it's going to be from distal so from proximal to dist. So it's a recon conversion. So how do we know if it's normal or abnormal? So the clinical history is going to be really important. Don't use this diagnosis if that is like if it's a completely like healthy patient with pain like there has to be a reason you have to have severe anemia you have to be on on a granulosite stimulator factor treatment to be able to call it but you can see in this example how in 2018 it was normal 2018 he had post treatment response from bone matter recon conversion he was on granulos simulator factor and then in 2020 as the treatment stopped s it goes back to normal bone marrow. So this is a normal process that you don't have to confuse with metastasis. So as we have discussed throughout this talk the bone marrow abnormalities can be either in distribution. So that's why you need to know normal distribution or signal abnormality. So the T1 is too dark or the T2 is too bright. We can also divide the bone marrow normalities in focal, multif focal, diffuse or treatment effects. And we don't have time to go through all of them individually, but my goal is to give you some um tips to be able to define to decide if you should raise concerns or if you should um actually be more conservative in your recommendations. So focal lesions we have of course infection focal lesions can be infections tumors any type of primary bone tumor multif focal we always think about metastasis langular hyocytosis CRM and in children particularly in a small children we think about infection which in adults we don't think about infection just because in children the osteomiitis is going to be It has a hematopoetic like a um is a spread by by bacteria instead of by direct contact which in adults is like you have a diabetic food you have an ulcer and usually it develops osteomiitis but in children they usually have just bacteria so it can sit in multiple bones and we have a diffused bone marrow infiltration so when we think about storage disease leukemia anorexia anemia But we have to think as I said about neuroblastoma and sometimes rabdo in babies they can spread diffusely within the bone marrow and of course we need to talk about treatment effect which is what we just talked about bone marrow recon conversion. So let's talk a let's talk a little bit about focal bone marrow lesions and my rule for focal bone marrow lesions in the differentiation between is this benign or malignant like should I recommend the biopsy or this is a non aggressive um pathology I use the T1 so as as you will hear me throughout this talk for me the most important sequence is the T1 for bone marrow why because benign lesions or inflammatory lesions are going to have illdefined margins on T1, right? Because the bone marrow infiltration is going to be more diffuse, right? It's going to like the pass or the edema is going to start going through the medularary canal, but it's not going to be replacing the fat if that makes sense as as as abrupt. So, in this case, so this is a 12year-old with osteomiitis. We can see here on the T1 how it's really difficult to create a true margin of the abnormality on T1. So if you cannot follow the abnormality on T1 with a pencil is most likely non-aggressive. So it's most likely a benign lesion. And if you really think about it is different to radioraphs. So in radioraphs if you can define your margins that are escllerotic and you know exactly where they are. to think that it's like makes you feel more comfortable but in MRI it's difficult and it's the T1 if you cannot follow it it's a good sign so inflammatory lesions we have of course controltomas in the epiphyses which you are going to have a lesion with a lot of inflammation we have LCH osteotoma osteomiitis and as I said like the bone marma you're going to see it better on the T2 but the T1 is going to tell you how to characterize it So in this case we can see that there is a morphocal lesion here in the metaphysis of the distal femur. So that's a focus of osteomiitis with transfacial extension into the epiphyses with an sub perostial absess which is pretty common in kids and this is a focal non-aggressive lesion consistent with osteomiitis. So when we talk about malignant tumors um the the rules are the opposite on T1. So if you can take a pen and define the margin on T1 with a pencil that's abnormal right because that means that it's a bone marrow infiltration process is moving the fat from the bone marrow and usually we see that in osteocaroma ewin saroma or lymphoma. So, as I said, the T1 is your margin. And when you're doing pre-operative assessment or initial assessment of these lesions, I always recommend my trainee to measure it on T1 because some of the lesions could have edema on T2 and it's really hard to know exactly what is the true margin of the lesion or if it's just reactive edema and I think the T1 is the most useful. In this case, there is no doubt that it's an osteocaroma case. We can see the abnormality on the radioraphs with the sunburst perostial deb formation and the model appearance the illdefined margins but as I say the T1 is going to give you the clue with defined margins. So we have here two different cases in the distal femur. So the first case you are already familiar with which is the osteomiitis case illdefined margins but this is another case of osteoto saroma. So if you can grab a pencil and you can draw the line that's an aggressive lesion even if you don't have the radioraphs but hopefully you have the radioraphs in these cases but as I said the T2 is really hard to define where is the margin of this lesion. The T1 is going to help you to define exactly where is the lesion. The T1 is super useful to evaluate focal bone marrow anormatics. So let's go through some cases. So this is a this is actually I think it's like shag UTP and I asked for interesting pediatric msk cases like images just to like have it here and and actually it's really interesting they don't make any sense but but they are indeed interesting if you really start looking at them individually. So let's see so this is a 16 year old with pain um in the distal tibia. So just starting with the radioraphs this is a concerning lesion right so you have a litic lesion in the distia the margins are not well defined there is a narrow sort of transision even in this radioraph is a little bit hard to see but there was there could be an aggressive looking perostial newborn formation with a common triangle here so it doesn't look great right so when we did the MRI we confirm that it's an aggressive lesion and I'm showing these two because sometimes unfortunately we don't have the radioraphs when we're looking at the MR and the MR can be misleading. So in this case you can follow the margins with a pencil on T1 that's aggressive. We can see on a sturd that there is not that much bon maradema. There is an extra ois of tissue component that enhances and this was a case of osteiocaroma even though we didn't see any osteo forming matrix in the radioraph. So sometimes it's really hard to differentiate between osteio saroma and e-win saroma but the tin one helps you to say that this case needs a biopsy. So this is another really interesting case. Um it's an unmini case. So if you haven't seen one of these I hope after you see this case next time you see if you have this case you're going to be able to just give the diagnosis because it's is relatively rare. It's relatively uncommon but the imaging findings are pretty characteristic. >> [snorts] >> So we have a 15 year old with at a traumatic recurrent knee pain and a fusions for two months. So the radioraphs are pretty much normal and then when we do the MRI we can see that there are abnormalities in the bone marrow that there are multif focal. So here is involving the distal femoral epifyses the medial femoral cond and it's involved with the proximal tia from the pesosis to the metaphysis with transfacial extension. That's like a little atypical. But more importantly on the T1 is that you have sharp well-defined margins, right? You can draw with a pencil. So if you really think about multif focal focal lesions that they're normal on radioraphs, your differential diagnosis gets narrower. So this is even though it's multif focal, it looks aggressive. um on the st sequence you can see T2 abnormalities and in postcontra sequences more importantly is that it has these um ser serpentine h areas of postcontrast that look like inforts so as I said if you haven't looked at this before I invite you to remember this because this is an admin for primary oius lymphoma and Dr. Duffy and Dr. Eglund from Boston Children's. They published this in 2023 a series of these cases and they realized they all look the same. They are rare. Of course, primary o lymphoma is rare. They usually start in in the lymph nodes or the spleen or the thin but this is rare. This is a primary of the bone. And as I said the the key features to make this diagnosis is multifocality epiphysicial involvement sharp T1 margins and then an enhancement pattern that look like inverts erh and most importantly post therapy they can have persistent or residual osis abnormalities even if it's like a good treatment response. So this is another case. This is a 12 year old with back pain. And this was a case that was I think it was done overnight and the fellow was in charge of of preliming this. And what caught the eye of the fellow was this like T1 T10 abnormality. It looks really heterogeneous on T2. It doesn't have contra enhancement. It doesn't enhance it normally. it has some like parispanals of tissue like prominence. So he called like this could be a metastatic lesion. This patient has a a a really old history of neuroblastoma when he was a 2year-old. So it's like oh could this being something focal in T10 but what it was needs and this is why the diffused bone marormalities are so hard to identify is that it's not only T10 it's the whole spine is abnormal. So as I said go to your team one and in the spine you're going to use the intervertebral disc as your gold standard to evaluate if it's like higher or lower signal and you can see that all the bone marrow is lower signal that your intervertebral disc so this is completely abnormal the T2 is misleading just because it's so diffusely abnormal that it's hard to see and then in this case it has a more like in eskeemic h processing of the bone marrow infiltration in D10 and that's where your eyes go but this is a diffused bone marrow infiltration in uh unfortunate neuroblastoma recurrence 10 years later but like lymphoma leukemia can look like this correct so any bonear infiltration process can look like this and in this case it was neuroblasto so this is a 10 year old that present no sorry a five year old that presented with um thigh pain. We did the radioraphs we can see that there is um non-aggressive but abnormal perostial newborn formation in the femoral diaphosis. So we recommended an MRI and when we do the MRI we can see that there is a more focal intramularary lesion that is heterogeneous on T2 low signal on T1 but importantly there is all these surrounding bone marrow normality. So as I said where do you measure do you measure the whole femur and on T1 this bone marrow single anormality it is non-aggressive right it goes all the way to the distal femoral metadata but it's not aggressive and you see the pattern of enhancement is not aggressive you cannot draw it with a pencil so this means that is an inflammatory mass right like there is a lot of inflammation surrounding this lesion and even So um LCH can look like anything. Every time in a child that you have an intramularary lesion with extensive inflammatory changes, I think your differential diagnosis should be LCH number one, two, and three. And of course, this patient will need a biopsy. H but this is a pretty characteristic for LCH. So, we're going to go to our last case, which is really um abnormal. I actually have seen this only in conferences until last year with this case. So, this is a 15year-old with a horrible history of fulminant success. You can see that he had um cardiac arrest outside of the hospital, a multi-organ failure, a multiple infections, opportunistic infections including cutaneous micro micosis. So he was a pretty pretty sick kid. Um after he was getting better and he was more responsive, he was complaining of hip pain. So he went for an MRI of the hip and these were the initial images. Erh because they were concerned about osteomi. So we did like a fast protocol which is like a T1 and a stir sequence and the tech sent me these images and I was looking at them and I was like and the tech was like oh do you want contrast like what do we want and and the images look really abnormal. I want you to think about which one is the star sequence and which one is the T1 sequence. And I'm going to show it now. So this and the clue is actually in the urinary bladder [laughter] because the it's so abnormal but you won't be able to know just from the fat the muscle and the bone marrow. So this was labeled stir sequence but this doesn't look like a stir sequence like the stial have fat suppression and you see the subcutaneous high signal which is abnormal. the bone marrow is too hypo intense. So it's really abnormal and this is what she was describ what the technology is like labeled T1 which is again abnormal where is the fat in the subcutaneous tissue where is the fat within the bone marrow this is a 15 year old you should have more yellow fat particularly in your feal head so it looks really really abnormal but if you see the bladder which is fluid it maintains the same signal so when you see is and I want you to think that this is oh it looks like the images are flipped right it looks like this looks like a T1 and this looks like a stir sequence so the first thing that you have to make sure is that there is not a problem with the labeling so I called the tech right away no problem with labeling are you sure that you activated the fat suppression in the in the stir and you didn't activate fat suppression on T1 correct are you sure that the gradients are working in the scanner like did we scan another patient today that didn't have any problem and she said yes everything yes and the way to prove that this is a true flip-flop phenomenon is that you can either do an spectroscopy and check how much fat you have in the subcutaneous fat and the bone marrow or easier which is the thing that I did I requested a Dixon sequence a Dixon with water inphase and fat reconstruction and you can see that this is a completely different technique And it shows the same finding. So in the water you can see that the s there is water signal in the subcutaneous fat right in the fat there is no fat signal that there is no bright signal on the fat. So this is like the findings were true and interestingly this patient underwent an MRI the day before of the elbow and this was read as many technical issues we are unable to assess like patient will be rescheduled because of technical issues with the scanner and if you see it's the same findings right there that is the stir sequence looks like a T1 the T1 doesn't look like a T1 there is so much bright signal on the subcutaneous fat and this was a true case of a flip-flop phenomenon. So a flip-flop phenomenon is also called zerous atrophy of the bone marrow or gelatinous transformation of the bone marrow. That looks really scary but what it means is that there is a catabolic state which this patient had like multifocal fa multiorgan failure. There is progressive depletion of the fat and protein stores and then all that fat within the subcutaneous tissue as well as the bone marrow is going to transform into hyuronic acid and that's the reason why you have fluid like signal in the bone marrow as well as the fat. This is extremely rare and you can see it in like cactic states anorexian nervosa or HIV AIDS. um is really rare but I'm sharing them with you because I I learned a lot from this case. So if you have a question always use a different technique of expression like use a dixon that can give you the fat and the water and you are sure that this is not a technical problem. So in conclusion it's really important to identify what normal looks like in the normal bone marrow in children so you can so you don't think that this is a an abnormal bone marrow infiltration. You need to learn the rules of what normal bone marrow looks like. So remember first it converts distal to proximal and it converts metaphysis diaphysis metaphysis epiosis diaphysis and metaphysis. The red maro should be higher signal than muscle and t1 and I believe that the T1 is the best sequence to characterize the red marrow and to increase or decrease your concern in these patients. So, thank you so much and I'm open for questions. >> Thank you so much for that lecture, Dr. Bedoya. That was excellent. We are opening the floor for questions. So, if you have any, please go ahead and put those in that Q&A feature. Uh, and there's one in there right now, Dr. Dora, if you're able to pop that open. I am, but I'm sorry, I don't see a question. Try hovering over the top of your Zoom. You might see the Q&A with a question or the bubble with a question mark in it. >> I'm sorry. >> It's okay. >> Oh, question mark. Yes. So, in vertebrae, how can you see bone recon conversion? So, in vertebrae, I mean, it's hard because in vertebrae like you you can have normal red marrow in in women who have their their perips, they need more hematopesis. So, it's normal to have red marrow. So if you only have like lumbar spine like it's really hard to know but the normal red marrow should always be higher signal than the intervertebral disc. So that should be your normal control to know if it's abnormal or normal and thank you so much. Do you have any experience with whole body MRI for M evaluation? So that's a really good point. So it depends on what you're looking for, right? So for example for and this is a this was a big discussion in in in the society of radiology meeting this this this month in in in Boston because it's what you're looking for. So in patients of CNO where you only want to see focal areas of osteitis or like abnormal high T2 signal sometimes that's the only thing that the or that the rheumatologist need. So a T2 may be enough. However, h I always recommend to do a T1 and a T2 stir of the whole body MR because sometimes there are some lesions particularly in cases of um um for example in le from many cases where you are like any abnormality is really abnormal but these kids they can run they can hurt their knees they can like have a lot of contusions and edema and I feel that T1 helps me to raise my concern concern or not. So if I see that there is a focal lesion and then the T1 is too dark, I say we need additional imaging, we need biopsy, we need we need to do more for those whole body MR. If I see that is an area of common contusions like femoral condoms and the T1 is non-aggressive, I may say, oh, let's just do a radioraph in three months to make sure that the nothing is there. So I think the T1 helps you with that in the whole body MRI. Right now in Europe, what they're doing for whole body MRI is that they are doing a T2 stair and then they're doing no sorry not a T2 stair. They're doing a T2 Dixon corona and they are just reconstructing the water which looks like a stair right like it's like a fat suppress T2 fat suppress and then they reconstruct the fat like the T2 fat sign Dixon and that's going to tell you if there is fat within those lesions. So use all your tools uh that you have. I know sometimes in in body imaging for kids we don't have a true T1 sequence erh but usually we have um an in and out of phase so you can use those to see if it's abnormal abnormal and if there is any question always add your key one. H someone asked how does myo fibrosis look? H so myo fibrosis can be really hard to see on MRI. I feel like it will be dark on T1 and dark on T2 but sometimes I have seen cases where it looks like a I mean the clue for me is a T2 particularly in myo fibrosis but I haven't had a case where I'm confidently um like I know it looks abnormal and I recommend a bone marrow aspirate to make sure like what it is but I that's why I didn't I don't have a a true case but it should be a lower signal on T2 is the rule there is another question is the rule of char margin and TY apply on adult malignant tumor I I don't see why not um I I think I don't see why not I feel it's just that in children sometimes we are into like is it normal remarrow or is it a pathology right like that's that's how we are usually finding ourselves And that's why we use that T1. But I don't see why why not. I I have noticed that most of the primary metastas some of the metastasis h they all have sharp T1 margins. H but you have to be careful with um post treatment changes because in the post treatment changes they get more fatty infiltration even if they are still present on the T2 and the T1 can of be a little misleading. But I use the T1 a lot to evaluate metastatic disease also. So I don't see I don't see why not. Erh, how do you differentiate osteoporotic spine fractures from a malignant one? So that's a really good question and I think this goes with adult T1 signal. I train under Dr. Vardino and I remember many times that she was saying to me that that a a pathic fracture if there is like multiple myoma or there is lymphoma or something there you should still see a little bit of T1 bright signal when compared to the interverial disc edema the same it should be like illdefined and the T1 will help you but you should see a little bit of normal um red marrow right which is what we discussed Today if you see complete like a facement of the normal T1 signal like that means that it's way darker than the interverial disc you have to raise the concern for a pathology fracture. H I think the T1 helps also like I mean use all your tools if if you have sometimes like diffusion helps that too but it can be hard sometimes but I do use the the T1 as that rule like I remember Dr. Ben Cardino saying that if it gets rid of the fat that is malignant until proven otherwise and and I guess that the MRI is really helpful to differentiate fat from just like fluid. Um how all patients okay in many sorry another questions in many old patients diffused dark T1 signal if it still looks okay how do you interpret? So, so in all patients diffuse dark signal is abnormal, right? Because there is no reason why like it's not red marrow, right? So why do you have diffuse and and that's where some cases of um of diffused bone marrow infiltration can get lost, right? So if I only see like a really dark T1 signal, I am concerned about a bone marrow infiltration and I will recommend a bone marrow infiltrate if there is no other reason to explain it. Right? If there is no severe anemia, if there is no um granulosite stimulated factor, um I feel that T1 is so useful because every time if I see a lesion or something on the T2, I open my T1 because if it's bright on T1, you're like, okay, this is like non-aggressive, right? like this is either a venus malf for what we call an intraisa or this is focal fat deposition. So the T1 is your is your is your clue and if it's dark on T1 I I I I will raise my concern and I will follow it. Can TV Okay, another question. Can TV cause um diffuse vertebral body loss on T1 and T2? So I guess that it depends uh on the bone marrow infiltration. Um the answer is is yes. Um and it will look like like but it will look more illdefined. It will have some like edma around and I guess you always think in TV about like the multi-level involvement the dis preservation like you have to use other rules um to be sure. Um but it does and the other question is is T1 Dixon helpful? Um I I think it's helpful. Um it depends on what you're looking for but but I think it's helpful if you have like in older kids like if you have like in out of phase so you can see if there is drop of signal in out of phase to because you're always just trying to look if there is microscopic fat right like if you have microscopic fat is is is a good sign and so so yes I I find it helpful but I I like my routine T1 um in all my pediatric protocol cases um like I have to play more with the T1 Dixon like we use T1 Dixon for the abdominal imaging in kids just because you can use those two sequences um without any any additional sequences is it's helpful um but if you have any question just add your sad corona okay I think that those were all the questions >> I think you got them all yeah thank you so Of course. >> Yeah. Thank you so much for this presentation. That was fantastic. Really appreciate you being here. >> Of course. Happy to be here. 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