Hi, everyone. Welcome to our live AAPMNR 2020 virtual session on Fundamentals of Interpretation of Musculoskeletal Radiology for the Physiatrist. We have a great panel of presenters today to do a crash course on how to interpret shoulder and knee x-rays and MRIs. Just a reminder that this is more of a basic overview, and we will not be addressing any of the more advanced sequences and views. A couple of housekeeping things before we get started. So on the left side of your screen, there'll be a chat field, and so you can pose questions. We'll be answering the majority of those questions at the end of the presentation, but we will have someone monitor the chat box throughout the presentation to answer any quick clarifying questions. We also have some polling questions scattered through our presentation, so please try to answer them quickly so we can stay on time here. All right. So I want to first start off by introducing all of our great panelists that will be speaking today. So to start us off, my name is Dr. Jen Suhu. I'm an assistant professor at Weill Cornell Medicine in New York Presbyterian and also serve as the Associate Sports Fellowship Director here. Next, we'll have Dr. Lindsey Ramey-Argo, who is a musculoskeletal medicine physician at WellMed Medical Group and also serves as volunteer faculty at the University of Texas Southwestern Medical Center. Next, we have Dr. Samuel Chu, who is an assistant professor at Northwestern Feinberg School of Medicine and the Shirley Ryan Ability Lab, and he also serves as the Sports Fellowship Director and Associate PM&R Residency Program Director. Next, we have Dr. Nathan Olovson, who is an assistant professor in the Division of PM&R at Washington University School of Medicine and also serves as the Director of Musculoskeletal and Pain Curriculum and is the Associate Division Chief. And last but not least, we have Dr. Catherine Yao, who is also assistant professor here at Weill Cornell Medicine in New York Presbyterian and also serves as the Director of Pediatric and Adolescent Sports Medicine and the Director of Dance Medicine. All right, so I'll be kicking us off here discussing shoulder x-rays. I have no financial disclosures or conflicts of interest. So overview of what I'm going to go over, I'm going to go over the standard shoulder x-ray protocol and views and then spend the last couple of minutes talking about other common views that we might see. So we want to start off with the polling question. So if everyone can take the next 15 seconds here to answer this question, and then we'll see what the results are before we move on. Maybe another five seconds here. All right, looks like everyone has finished. So it looks like the majority said A. So actually the correct answer here is B. So moving on to my next slide here. So standard shoulder X-ray protocol, what you usually wanna order in the non-traumatic patient is standard AP view, true AP view or a Greci view, scapular Y view or lateral view. So actually A, I had both AP lateral and scapular Y and lateral and scapular Y are actually gonna be the same view and then the axillary view. And I'll go through these in a little bit more detail here. So standard AP view, so it's taken but with the central beam directed toward the humeral head, the true AP direction relative the body, it can be done in both either external rotation or internal rotation, but it's most commonly done in external rotation. And an easy way to memorize what this view looks like is that the humerus and glenoid overlap. And as you can see in this picture here, I don't know if you can see my arrow, but you can see the humeral head and the glenoid overlap. This is just a brief slide looking over what the difference between what AP looks like in external rotation versus internal rotation. If you can get both, that's great because you can then see the entire humeral head. On the AP in external rotation, you can see the greater tubercle of the humerus better. And then the AP in internal rotation, you can see the lesser tubercle of the humerus better. What you wanna look for on the standard AP view is you can get a really great view of the acromioclavicular joint, the distal clavicle. It's good for evaluating for fracture or dislocation. And then you can see calcific tendonitis as well. The next view is the true AP view or the Gracie view, which is the true AP of the shoulder where the patient is rotated about 30 to 40 degrees so that the plane of the scapula is parallel to the cassette as you can see here on the right. What you end up getting then is a picture where there's no overlap of the humerus and the glenoid, as you can see here with this picture on the right. What you wanna look for on this view is you wanna look at the glenohumeral space. And then you can also look for any subtle superior or inferior migration of the humeral head as seen in instability. Here's just so we can just really pound this in, the difference between standard AP versus true AP. Again, standard AP, you can see the humeral head overlap the glenoid, which you do not see on the true AP. And then you can see the acromioclavicular joint better on the standard AP, and you can't see it as well on the true AP. For the scapular Y view, otherwise known as the lateral view. So the patient is positioned in an anterior oblique position with the anterior aspect of the examined shoulder in contact with the cassette. And the beam is then centered on the posterior aspect of the shoulder. The contour of the scapula projects as a Y, which is why it's called the Y view. The downward stem of the Y is the body of the scapula. The upper forks of the Y are the coracoid process anteriorly and the scapular spine and the acromion posteriorly. The glenoid is then located at the junction of the stem and the humeral head is in the center. This shows a good lateral view of the shoulder and an oblique view of the humerus. And it's about 20 degrees of true lateral. So this is what that looks like on X-ray. And this shows excellent visualization of whether there's an anterior or posterior dislocation. If there's a fracture of the scapula, coracoid process, acromion process, or proximal humeral shaft. And it's also a good view to get a sense of what the acromion type is. There's a better view for acromion type, which we'll talk about later, but it's at least something that you can look at here. And then just briefly hitting the different acromion types, there's actually four, but three, which we really look at and see most commonly. So type one is flat, type two is curved, and type three here is hooked. I don't know if you can see that so clearly on the screen, but definitely something that you wanna look at if you have someone with impingement to see if they have this as a risk factor. And then last view that we'll go over here is the axillary view. So the patient is supine and the arm is abducted to 90 degrees, although there's several variations which require less than 90 degrees. The cassette is placed to the superior aspect of the shoulder and the beam is centered at the mid glenohumeral joint and directed in a distal to proximal direction, while to 15 to 30 degrees towards the spine, which leads to a tangential view of the glenohumeral joint from below. This is, in general, a more uncomfortable view for patients and very difficult to obtain in people with true dislocation and then you really want to be careful ordering this if you suspect a humeral head or humeral shaft fracture because you can actually make this worse. This view also can sometimes have some radiographic quality that's limited because of the rapid change of overlying soft tissue density. This is what the axillary view looks like on X-ray and this gives an excellent visualization of dislocations or subluxation. It gives really clear visualization of the relationship of the glenoid to the humeral head and then can see all these different fractures that I've listed here on the slide. When you have someone coming in who had some type of trauma to their shoulder that you're not sure what it is, the standard shoulder X-ray protocol is getting an AP view, either external or internal, basically whatever you can get most comfortably with the patient, and then the lateral or scapular Y view. Briefly, in the last couple of minutes here, some other common views that we see. The Zanka view or the AC joint view, you can get this with the patient standing arms freely at their sides. The beam is directed towards midline of the body at the level of the AC joint with about a 10 to 15 degree cephalad angle. The patients may hold weights in each hand which can accentuate the separation and the most important thing here is to compare to the contralateral side. As you can see here, you get a really great view of the AC joint and then you wanna consider this view when you're looking for AC joint separation, AC joint arthritis, or distal clavicular osteolysis. The supraspinatus outlet or NIRS view, this is very similarly obtained to the Y view that I talked about earlier, but this view is then directed towards the superior aspect of the humeral head angled about 10 to 15 degrees. This gives a real excellent visualization of acromion and the acromion type and any abnormalities of the acromioclavicular arch. This is a view you wanna consider with someone if you're working up impingement. The striker notch view is done with the patient supine or upright positioned as this person is on the right hand side. You wanna get this done after an anterior dislocation. This is what that looks like under x-ray and it gives a real good view of whether this patient has a heel sex deformity or flattening of the posterior lateral humeral head. The west point axillary view is done with the patient placed prone on the table, positioned like this. I'm not gonna read through all of this for time's sake, but also a view that you wanna consider after anterior dislocation. This can be difficult to obtain in acute trauma. This is what that looks like and it gives you a really excellent visualization of the glenoid and specifically what you wanna look at here is for a bony bank cart, but it can also give you a good sense of if there's a proximal humerus fracture as well. Just take home lessons. Standard x-ray views in a non-trauma setting. It's the AP, Gracie, axillary, and scapular Y view. The minimum number of views you wanna get for an acute trauma of the shoulder is AP and scapular Y view and then the instability series includes the AP shoulder, axillary, striker notch, and west point axillary view. These are my references. Thank you and please save any questions for the end of the presentation. Hopefully that gave you a good overview of how to work your shoulder x-ray and now I will pass the baton over to Dr. Argo who will be going over shoulder MRI and common shoulder pathology. So hi, I'm Lindsey Argo. I am gonna be talking for a few minutes about shoulder MRI and then we will be jumping into common shoulder pathology. Out of respect for time, we're gonna jump right in. I have no financial disclosures and I wanna start off with a polling question. Just to see when you guys first open an MRI, what views do you typically look at first? There's no right or wrong answer here. I'm gonna give you guys a minute to read because I know there are a few options, perfect. I'll give about 10 more seconds for any late answers. So it looks like we're mostly doing two panels of either a coronal and an axial or a coronal and a sagittal, okay? So the objective of our talk is we're gonna go over the common MRI sequences that you'll see when you order a shoulder MRI and we'll discuss the planes. And then I'll tell you guys my approach when I read an MRI. I don't think there's a right way to do it, but I use an acronym, BLT with fries because I'm a food-centric human. And then we'll discuss what I consider to be a home-based view for the coronal, the sagittal and the axial planes to help you get oriented if you're ever a little confused about what you're looking at. And then finally, we'll look at some common pathology on both X-ray and MRI. My take-home message for you guys is gonna be that I really can't teach you how to read an MRI in eight to 10 minutes, but hopefully I'll give you a few tools so you can go practice. So it really takes an understanding of three-dimensional anatomy and just practicing over and over again. And sometimes I'll have trainees or new attendings that just say I don't see MRIs enough to feel comfortable with it. And so there are a few resources you can use that give you labeled T1 and T2 MRIs that we'll talk about. So I've listed them here. So hopefully after the talk, you can go and practice what we're talking about and just feel more comfortable on your own. So the sequences you'll typically get, I usually categorize sequences as either being fat-sensitive or fluid-sensitive. You will typically get a fat-sensitive sequence that's a T1 or kind of an intermediate signal intensity for proton density, or you'll get a fluid-sensitive sequence that is a T2 or proton density with fat suppression. And that's typically how I group them together is being more fat-sensitive or being more fluid-sensitive with fat suppression. For the planes of the shoulder MRI, what you'll see is the planes are actually relative to the glenoid fossa rather than anatomic position. So on the far left image here, you'll see a T1 coronal oblique. And so this is correlating with the purple slice on the axial image on the far right side. So it is perpendicular to our glenoid fossa. The sagittal is a sagittal oblique that is parallel to the glenoid fossa. So that is correlating with the red line on the axial image. And then our axial is our standard transection. And when you get a shoulder MRI, I think every institution does it a little bit differently as to what sequences you'll obtain, but you'll usually get two coronals, a fat-sensitive and a fluid-sensitive coronal. You'll usually get two sagittals, a fat-sensitive and a fluid-sensitive sagittal, and you'll get one or more axial. Where I am right now, I only get a fluid-sensitive, but where I was previously, I would get both a fluid-sensitive and a fat-sensitive. And that should be enough to define most pathology. And you'll also get a localizer tracing with three planes with a larger field of view to do a larger sweep for other pathology just outside of your close shoulder view. So I talked about my approach. So I tend to look through an MRI and I start by focusing on the bones and joints, and we'll look at these on each of the views. Then I look at the ligaments and the labrum, and then I look at the tendons and the muscles that attach to those tendons. And then finally I go through and I look for fluid signal, usually on my fluid-sensitive sequence. And so I'm looking for neurovascular fluid, I'm looking for physiologic joint fluid, or I'm looking for pathologic fluid, either in a bursa, a joint, or where a structure might be torn. And the way I start looking at an MRI is on a coronal view. So I tend to do a two-panel coronal with my fat-sensitive sequence on the left and a fluid-sensitive sequence on the right. And I'll walk you through that. But before I even open it, I tend to run through what I'm expecting I'm going to see so that when I open up the image, I know what it's gonna look like before I open it. And so for me, I will open up a coronal MRI in the center of the glenoid fossa, and I'll start by saying, what bones am I expecting to see? So I'm gonna walk you through what I go through before I even open the MRI. So when I first look at it, I think I'm gonna see the humeral head, humeral shaft, the bone marrow, the glenoid fossa, the distal clavicle, and the acromion, and I'll see the glenohumeral and the AC joints. And once I feel comfortable with that, then I layer on what are the ligaments that I'm gonna see in this view. So largely your superior and your inferior glenohumeral ligaments. You'll see the capsule around your AC joint, and you'll see your superior and inferior labrum in this view. What tendons and muscles am I focused on in this view? I think this is probably the key view that we start with with our supraspinatus muscle and tendon as it goes on to insert on our greater tuberosity. We can also see our deltoid and the myotendinous insertion onto your acromion. And then if you go anterior from the center of the glenoid, you can see your subscap, or if you go posterior, you can see your infraspinatus and your teres. And then finally, I say, what fluid am I expecting to see and what fluid might I see that I'm not necessarily expecting? And so for neurovascular structures, we'll often see our suprascapular nerve sitting in our suprascapular notch with surrounding vessels. We may see a subacromial subdeltoid bursa, and we may see fluid in the inferior pocket of the joint. And so once I've gone through that and I know what I'm expecting to see, it's very easy when I open up my MRI and I see this, because I already know almost everything that's on the screen. I've labeled it here for you if you can see that. A few things that I didn't draw out, you can see your subscapularis sitting in the subscapular fossa. You can see your trapezius muscle on top of your supraspinatus. And you can even see your long head of your biceps and the tendon that's coming up and wrapping around the humeral head to insert on the superior labrum. But other than that, you should have a pretty good understanding of what you're looking at. So this is, again, our fat-sensitive sequence that looks very close to what we're used to for anatomy. We know what we're expecting. We can now name everything on the screen. And so I would then open up in the plane beside it a linked image to our fluid-sensitive sequence. And I would scroll from my home-based position in the center of the glenoid fossa anteriorly, looking systematically through the bones and joints, the ligaments and labrum, the tendons and muscles, and then looking for fluid on my fluid-sensitive sequence on the right. And that's how I do it every time to make sure I don't miss anything. For time's sake, I'm not gonna walk us through slice by slice, but I would ask you to take some time to practice doing that yourself so you can identify things that live anterior or posterior to this home-based view. I'm gonna slide on to the next view, though, of a sagittal, and we're gonna walk through it the exact same way so you can get comfortable with the home-based view of a sagittal oblique. And so we're gonna do the exact same process where we start with what bones and joints we're expecting to see. So labeled here are the bones in what I consider to be the home base, which is just medial to the glenoid fossa. We'll layer in any ligaments and labrum that we're expecting to see. So here, largely, we'll get a better view of our AC joint ligaments, our CC joint ligaments. We'll layer in our muscles and tendons that we're expecting to see, and this is a great view of the rotator cuff muscles, particularly for your subscapularis and your infraspinatus. If you struggle to find a line that defines supraspinatus from infraspinatus, it's very easy to go to this home-based view because they are separated by your scapular spine, and then just start medial and scroll lateral and watch that muscle turn to tendon, and it's much easier to define, am I looking at supraspinatus, infraspinatus, teres, if you do it that way. And then finally, we add in our fries. So what fluid are we expecting to see? So largely, our, again, subacromial subdeltoid bursa there. All right. And so when we pull up our T1 fat-sensitive sequence here, you'll see that everything looks very similar to what we're expecting it to look like, and we can now identify nearly all the structures on our screen just based on what we were expecting, and then if we open up a two panel with the fat-sensitive and the fluid-sensitive side-by-side and link them, we can scroll from medial to lateral and feel very comfortable that we know we're in the supraspinatus, the infraspinatus, the subscapularis, and look at all those myotendinous structures, which the sagittal view is great for. Again, I do the same sequence of bones, ligaments and labrums, tendons and muscles, and fluid. And then the last series that I look at is our axial, so we'll go through this quickly. You essentially have your humeral head sitting in your glenoid fossa for your bones over the glenohumeral joint. You have your, now the anterior and posterior labrum are best viewed in the axial slice, and you can see your middle anterior and middle posterior glenohumeral ligament best in this axial view. Layering on our muscles and tendons, again, we can see our subscapularis anteriorly, infraspinatus posteriorly, and the surrounding musculature that's labeled here. And then finally, looking to see if there are any fluid. So you could see potentially a subacromial subdeltoid bursa, you could see a subcoracoid bursa, you could see your anterior neurovascular structures here. So then when we pull up our fat-sensitive sequence of the axial centered through the glenoid fossa, we know what structures we're looking at, and then we can pull up our T1 and our T2, or our fat-suppressed proton density, and link them and very easily look through those structures, again, with that same formula of bones, ligaments, labrums, tendon, muscle, and fluid. And that's how I do it every time, at least when I was first learning. As you get more comfortable, you might not need to always have your T1 or your fat-sensitive and your fluid-sensitive linked together, you may be able to go straight to linking your axial with your coronal, or your sagittal with your coronal, and go straight to a fluid-sensitive sequence. But if you ever get lost, I would encourage you to go back to those home-based views and just link a fat-sensitive and a fluid-sensitive together. Fat-sensitive can be very easy to identify anatomy, and fluid-sensitive can be much easier to identify pathology which we're gonna talk about in a second here. Once you master your home-based views, just practice, practice, practice going off your home base, go anterior, posterior, go medial-lateral, and go cranial-caudal, and you'll get very comfortable looking at all these structures the more you do it. For time's sake, we're gonna switch over to the common pathologies that we see in clinic. And so these are the most common things that I tend to see, and I've noted them here with the views that we typically see them on and the platform of imaging that we typically notice them on. So glenohumeral arthritis, glenohumeral joint dislocation, an AC joint separation, frozen shoulder, rotator cuff pathology, bursitis, and labral tears are by far the most common things I see as causes for shoulder pain. Frozen shoulder is really a diagnosis based on examination and clinical presentation, so you don't really need imaging for that. And labral tear is best seen on an MR arthrogram. So we won't look at the images of those, but we're gonna slide through a few images of the rest of these. So let's talk about glenohumeral arthritis for a second here. So there can be different types of arthritis. The image on the left is a pretty classic and overt image of a rotator cuff arthropathy where there is a high-riding humeral head. There is actually no appreciable space between the acromion and the superior margin of the humeral head on that AP view. And so that's pretty classic for a rotator cuff arthropathy. You'll also notice that the portion of the joint space that is most narrow is the superior margin of the glenohumeral joint. If you contrast that with the middle picture of more traditional osteoarthritis, you'll see that there is sclerosis and joint space narrowing of the inferior glenohumeral joint with large osteophyte sitting in the inferior joint capsule. So that's more classic for osteoarthritis. And then the last picture on your right is an MRI pointing out subchondral erosions, synovitis, and the portion of the joint that's more commonly involved in rheumatoid arthritis, which is typically the middle to posterior aspect of the joint. So all of these will look a little different on different forms of imaging. I personally think the best view to see traditional glenohumeral arthritis is the Gracie or the true AP view that Dr. Suhu mentioned previously, because it can often be misleading to look for it on a standard AP because of that overlap of the fossa and the humeral head that you see on the image on the far left. For, let me go back, for a glenohumeral dislocation, if it's a classic kind of anterior dislocation with significant overlap, you can often see that on a standard AP view, which is the image demonstrated on the left. But for your less classic images, like a posterior dislocation, that's often seen best on a true AP view, which is the image that is second to your left here, where you'll see a slight overlap of the medial border of the humeral head and the lateral border of the glenoid fossa. And then on that same individual, you can see that a little better if you go to your scapular Y, where you see the center of the glenoid fossa is not the same as the center of the humeral head. The humeral head is centered a little posteriorly. And then finally, it would really confirm it if you go to your axillary view, where you can see that the glenoid fossa is actually empty and the humeral head is lying posterior to the fossa. We won't go through all the different types of AC joint separation for time, but I've included an image of each for you to go back and look at if you're interested. But basically, if you're looking for AC joint separation, I typically get bilateral Zanka views. You could also do bilateral APs. I find them a little harder to interpret, but you're looking to see if there's an increase in the distance between the coracoacromial distance or the coracoclavicular distance from the symptomatic to the asymptomatic side, and if that clavicle is going superiorly, posteriorly, or inferiorly. So here's types one, two, and three labeled. And then what you'll notice here is type four is posterior and type six is inferior. So types four, five, and six. And then the last one we'll touch on is rotator cuff pathology, which is a pretty broad topic. It can include anything from tendinosis to calcific tendinitis to a true tear. So tendon tears come across my desk pretty commonly, and they're typically graded based on their size. So we think about their thickness. So going from the most cranial margin, which is our bursal side, to our deeper margin, which is our articular side, if they do not go all the way through, they're considered partial thickness. If they go all the way through from the bursal surface to the articular surface, then they're considered full thickness. A partial thickness tear is usually graded as being low grade if it's less than 50% of the thickness or high grade if it's greater than 50% of the thickness. And then a full thickness tear is usually described as being either incomplete, meaning it doesn't go all the way from the anterior to the posterior portion of the tendon, so it's not the full width of the tendon, or if it is, it's complete, or if it's involving multiple tendons, it could be a massive tear. And we often describe fat atrophy or retraction of the tendons in tears once that occurs. So I'm gonna give you just a few examples before we wrap up here. So this is an example of a coronal oblique fat-sensitive sequence on the left and fluid-sensitive sequence on the right, like we discussed earlier. And what you'll notice is that you've got a relatively low signal intensity supraspinatus muscle with a low signal intensity or black supraspinatus tendon as it's coming out to insert on the greater tuberosity, but you lose that black structure on your fat-sensitive image here. It almost looks like it's the same signal intensity as the deltoid muscle on top of it on the left. If we go to the right image, our fluid-sensitive sequence, much easier to see that there is actually a full thickness tear with fluid intervening in that space just deep to the deltoid muscle. So there is a full thickness supraspinatus tendon tear with some subacromial bursitis associated with it in this image. And then just to compare that to what a partial thickness tear might look like, on the left is an image of a partial thickness tear on a fluid-sensitive sequence. So again, we've got low signal intensity muscle with even lower signal intensity tendon. So tendon should be black on both fluid and fat-sensitive sequences. But as we follow that tendon out to its insertion site, you can see that there's relatively high signal intensity. It's not quite as bright as fluid, but it's brighter than the muscle around it. But it doesn't go all the way from the bursal to the articular side. So this is largely a high-grade, articular-sided partial thickness tear on the left versus on the right. You can see that there is bright fluid signal in the supraspinatus tendon that is contiguous all the way from the articular side through to that prominent subdeltoid bursa. And so that's consistent with a full thickness tear and subacromial bursitis. And that's where I will leave us today. We have a few references here, but I want to turn us over to our next speaker, Dr. Nate Olifson, who will be speaking about, is it knee x-ray, I believe. Hi, everybody. We're going to move on, actually, to the knee MRI talk. Dr. Olson's having some internet difficulties, so he'll be right back in. But I'm Sam Chu. I'm here in Chicago. I wanted just to talk to you about knee MRI, and Dr. Argo gave such a great introduction to the MRI interpretation, so we'll just launch right into this. I have no relevant disclosures for this talk, and our objectives today are really to review some of the common sequences seen in knee MRI interpretation. Certainly, I think seeing the x-rays from Dr. Olson later on will be helpful, but I believe we want to talk about some of the structures that we're going to see as well and recognize the normal appearance of structures, and then Dr. Yao later on will talk about some pathology. And then we want to talk about what structures are best seen in which plane. I do think that for the knee, it's a little bit easier to understand some of the location of certain structures compared to the shoulder, but what we're going to do today is talk about indications. You know, MRI of the knee can be helpful for many of the soft tissue structures listed here, including cartilage or meniscus, ligaments, as well as bony structures. And then the different plane we'll talk about today are coronal, sagittal, and axial. The coronal, I think, is better for some of the collateral ligaments in medial or lateral as well as the meniscus. The sagittal plane can also be used to see the meniscus, but also for cruciate ligaments, the ACL and PCL, as well as patellar and quad tendons. And then your axial view is great for the patellofemoral joint compartment. As Dr. Argo mentioned, there are a number of sequences that are common for MRIs of the MSK system. Of course, you have the T1-weighted fat-sensitive sequence and T2-weighted fluid-sensitive sequence that we're all familiar with. And of course, as Dr. Argo mentioned, the proton-density-weighted, which is both fat and fluid-sensitive, kind of an intermediate sequence. Fat suppression or fat saturation, as put in this asterisk, can be helpful. It essentially can help you accentuate bone marrow or soft tissue edema on some of the fluid-sensitive sequences, so you can make a little bit more of a differentiation there. So if anyone has a pen and paper or even want to bring up a notepad, I'm going to put up a couple of images over the next few minutes. And this is going to be just for yourself, just to see if you can identify the numbers, the numbered structures on the screen, and we'll talk about it. But this is a coronal T1-weighted MRI, and just even as a mental exercise, if you don't write it down, try to go through the numbers yourself. And we'll have a polling question a little bit later on for one of the sequences. But think about what you're looking at in this coronal sequence. Again, in the absence of being able to do this kind of live with a video, we won't be scrolling through as you might on an MRI, where you kind of go back and forth. But it might be good practice for us to look at some of these structures and identify them. All right, so we'll get to the answers here. Looking from the top, number one, you know, here is our coronal view, IT band on the top followed by vastus lateralis, and number five is vastus medialis. As we get down to things like number three and number four, we have your lateral femoral condyle and your lateral meniscus. As you wrap our way out to the other side, actually number seven points to just a portion of the PCL or the posterior cruciate ligament that is on the medial aspect of the knee here. And then you see your medial collateral ligament number eight kind of wrapping linearly on that medial aspect. This is just to give you a general sense of some of the structures, what you're looking at in this view. This is just a view of the proton density weighted, and this is actually a fat suppressed image. So again, you can see here the marrow is dark, it does contain fat, and this is a fluid-sensitive sequence. So you can see that meniscus are fairly well-defined here. It provides a little bit of a better contrast. So if you're looking for edema, both soft tissue or marrow edema, this might be a good place to look at. All right, we're going to move right along to our sagittal plane, and again, if you have something to write down with, we're going to just kind of take 30 seconds to have you go through one through 10 and see if you can identify these structures. We have a small subset on the very top right that shows you where we are within the actual knee itself on that axial view. As we work our way down here, I want to see what structures you are familiar with. A lot of them are very obvious and others a little bit more challenging. All right, so we're going to move on in the interest of time, but this is a labeled-out version of that. So we're going to start from the top left, which is the quad tendon, and then we get their femur and patella located at number two and three, fairly obvious. We have the patellar tendon listed as number five, and then really on this view, we have a great view of number nine, the posterior cruciate ligament, or the PCL here. You can see a little bit of the ACL here on this view, but we'll see another view of that later on. As we move a little bit more lateral here, so in general, we're going to look for this structure that's labeled by this red star, and essentially what we've done is slid lateral on this slide, and we're essentially identifying the structure, which is the ACL, or the anterior cruciate ligament. So previously, we were on the PCL on that view, and then we've slid a little bit lateral. We go even a little bit further, then we have another structure here listed with the red star, and that's going to be our meniscus. So we're going to see our menisci, both the anterior and posterior aspects of this, and you can see that, again, on still the same sagittal T1-weighted image. All right. This is our lateral meniscus, anterior and posterior horns. This is another view. This is our sagittal T2-weighted, as Dr. Argo was talking about. This is a fluid-sensitive sequence. You can actually see a little bit of fluid in that super patella recess, just behind the patella, and there's a little bit of a signal there. I just point that out because for those of you who do ultrasound-guided injections, this is oftentimes a target for accessing the joint through that super patella recess. All right, and this is a view of a proton-density-weighted sagittal image. Again, you can see the menisci located there, anterior and posterior horns, and these are normal appearances of the meniscus here. All right, and finally, we're going to get to the axial views, and this is a T1-weighted image. This is where we're going to have a polling question. I want you to look through one through seven here, but in particular, think about what you're seeing on number three, because that's what we're going to ask about in a second, and I'll have some multiple-choice questions. But we're thinking about one through seven. Just take a couple seconds to identify what you think those structures are referring to. All right, and we're going to pull up our polling question here, and these are the structures we're going to ask you about. What structure is indicated by number three? So we have a couple choices here, vastus medialis, lateral patella retinaculum, the articular cartilage in the patella, or the medial patella retinaculum. We will show the image again in a second, absolutely. And I think for the sake of time, we'll have it pulled up with the labels intact, but I do see most people coming in here. It looks like we've got about 55 to 60 percent people calling the medial patellar retinaculum and then about 30 percent on the lateral aspect and then a couple for the others here. So, correct answer is the medial patellar retinaculum. Thanks for that question in the chat here. Again, a little hard to tell on this image exactly which side you're on. There's a little clue on there where it was labeled LFC on the image itself, which is the lateral aspect, but number three is the medial patellar retinaculum. Number one is the lateral patellar retinaculum. And again, this is a great place to look for pathology, especially if you're considering somebody with a subluxation or a dislocation of the patella, you can look for an injury there. The remaining structures there are number two, the bicep femoris, number five, the medial gastroc, and number six, the sartorius, seven, the semimembranosus. Again, a good way for you to figure out which side you are lateral medial if you don't have the label, of course, is to pull up a cross-sectional view like the coronal picture that you might have and you might put two panels on and use your cut lines if that's available to identify where you are. Another view here are the axial T2 weighted, which is fluid sensitive and a similar cut, but you can also see the popliteal artery and vein there on the posterior aspect. All right, so I know there's a lot to go through and again, as Dr. Suhu mentioned, this is not meant to be a comprehensive overview, just to really show you some of the structures anatomically that you can visualize an MRI and I would really just take your time and practice, like I mentioned before, take a look at the images and all the different sequences and remember which sequences are good for certain structures. I really would also take advantage of whatever imaging platform you have to look at various images side-by-side so you can understand a little bit more of where you are anatomically. The other things I do talk to residents and fellows about is, you know, take a look at the image first and see if you can make a preliminary look at some sort of pathology that you might be calling and then if you have the radiology report, really then go back and compare your notes to that and use that as a way to look at what you've identified for pathology, look at a lot of normals as well if you can. So thank you for your time and really what we're going to do is move on. I think we do have Dr. Olson back on the line. So I appreciate everyone's attention and participation and I hope everyone's doing well. Thanks. Hi everyone. Apologies for the internet challenge, but we're back and ready to go. And if we could get my slides to the to the start and we're good. I'm Nate Olson. I'm going to be talking about x-ray basics for the knee. I have no disclosures to make. So the standard series of a knee x-ray in a non-trauma setting includes the following views. A weight-bearing AP, a weight-bearing bent knee and there's can be done in a number of different ways. The PA Rosenberg views that you will discuss the most. A lateral bent knee view and then a view of the patella. So starting with the weight-bearing AP, the patient is standing and the x-ray beam is projecting in a straight AP fashion with the knee in neutral alignment. Typically, both knees are included for a means of comparison. In this view, it's really useful for assessing alignment of the joint, looking for subtle fractures. And then most importantly, most commonly, we're obtaining this view to assess for any sort of osteoarthritis. One of the take-home points that I'd encourage you to think about would be that joint space narrowing is best assessed when you are doing a weight-bearing view. And a non-weight-bearing view may under-assess the joint space loss. Here's some labels applied for some important anatomic structures that you will be trying to note when you're looking at your AP x-ray. Just to drive home the point about the value of using weight-bearing or standing images to assess joint space loss, the picture on the left is a weight-bearing view. The picture on the right is a non-weight-bearing view. Adding the patient being standing really allows you to assess the true severity of joint space loss and in some instances can actually reduce the need for unnecessary imaging such as with an MRI. Next, moving on to the weight-bearing bent knee view. The view I'm first going to talk about is the PA or Rosenberg view. The patient is standing, but instead of having a anterior to posterior projection, this is now a posterior to anterior projection. And the knee is bent approximately 45 degrees. Again, knee is in neutral alignment. This is a great view to look at the condyles. So the condyles are a little bit more visualized because the knee is bent slightly and as a result, you can visualize some conditions that you may have trouble assessing for in a true AP standing full knee extended view. Such conditions like osteonecrosis or osteochondritis desiccant are really valuable. This x-ray is really valuable to assess for those. Now there are a few other ways to look at the notch and the condyles. These are typically described as the tunnel view, which is seen here and the notch view, which is seen here. Both of these are non-weight-bearing views and though although they are very good at looking at the intracondylar notch, looking at the tibial eminences and looking at the condyles, they are non-weight-bearing images. Here's just a labeled image of a tunnel or notch view. Again, driving home the point that it's really valuable to look for problems with the condyles as well as for congruency of the of the tibial plateaus. So now let's put this all together. We're going to compare the three different AP views here. Standing AP on the left, Rosenberg, the PA bent knee, and then the non-weight-bearing tunnel or notch view. Next, our lateral image. Note that the patient here is side-lying or could be standing and in the side-lying view the knee is flexed to 30 degrees and the hip is externally rotated. We'll compare this to a trauma view later. This is really good for looking at the position of the patella relative to the femur and as well as looking at the femoral and tibial alignment. Here are labels applied to our lateral image now. As we discussed earlier and we'll discuss later, this is a valuable view to be able to assess for a fusion because you can actually differentiate the pre-femoral from the suprapatellar fat pack and see that suprapatellar recess proximal to the patella. It's also useful for looking at patellar alignment such as patella alta or patella baja and looking at the integrity, although imperfect, looking at the integrity of the patella or quad tendons. Next is views of the patella. All of these views are trying to isolate the patella without any sort of super imposition by any of the other bones, such as the tibia or the femur. The top image is the merchant view. The bottom image is the lorine view. They really only differ in the projection of the x-ray beam, either superior to inferior or inferior to superior. And another view that many of us would be familiar with would be the sunrise view. Again, the only difference here is the knee is hyperflexed compared to the other views. All of these views are really useful at looking at the alignment of the patella relative to the femoral trochlea, looking at patella femoral osteoarthritis, patellar subluxation, and patellar fracture. There is some suggestion that the merchant view might be superior just because in the sunrise view, the knee is so hyperflexed that the patella may be depressed. Finally, we're going to move on to the trauma series. In this, the patient, we assume that they are, say, in the emergency department and they have a profound deformity to their knee or are non-weight-bearing and they cannot bend their knee. And as such, having a patient being supine allows you to still visualize the knee through x-ray without having any substantial range of motion necessary to achieve the appropriate image. In the supine AP, again, it's useful for trauma views, but it can really underestimate joint space narrowing. So if you see a non-trauma supine AP x-ray of the knee, you may not really understand how much joint space loss that patient has. Next is the horizontal beam lateral. In this, the patient, again, is supine and the patient's knee is hyperflexed. Next is the horizontal beam lateral. In this, the patient, again, is supine and the x-ray beam is passing from lateral to medial. This is different than the lateral either standing or bent knee view that we discussed in the non-trauma setting. In this, the patient really doesn't have to move at all from the PA view and the x-ray scope can just be moved around the patient. This is really valuable to look for major deformities of the knee, major effusions of the knee, as well as integrity of the quad and patellar tendons, as well as the patella itself. Unique to the trauma series are the internal and external oblique views. In the images here, the patient's rotating their leg. However, the x-ray scope could be moved around the patient. So, really, they would never have to move their knee compared to the PA or lateral positions that we just described. In these, the internal and external rotation of either the scope or the patient's leg allows us to visualize aspects of the tibia, fibula, as well as distal femur that may be missed on the traditional PA, AP, or lateral views. Specifically, these x-rays are really valuable in the setting of evaluating the proximal tibia and the proximal fibula, especially the fibula may be uncovered in total on some of these views that they may not be in a PA or AP view. So, our take-home points is really what is the difference between our standard non-trauma and then our standard trauma x-ray series. In the weight-bearing, views are critical to do in the standard view, standard non-trauma view, and then in the trauma settings, the patient will be in supine throughout the assessment. Last take-home point is non-weight-bearing images really can underestimate the amount of joint space loss and are best reserved for standard assessment in clinic. So, here is our polling question. In a non-trauma setting, which of the following is the typical four-view x-ray series of the knee? I'll let you read those, and then we'll look for the results. I'll just wait a little bit longer. All right, it looks like we have a consensus. So, most people have answered the standing AP merchant lateral bent knee in Rosenberg, which is the correct answer. The other views are just incorporating some of the non-weight-bearing images that would not be as appropriate in a non-trauma setting. All right, well, last, I will pass to Dr. Yao. All right. Hi, everybody. I am Catherine Yao with Weill Cornell Medicine, and I am going to jump right into talking about and walking you through a knee pathology that we see on both x-ray and MRI. And, again, some of the more common pathologies we will only have time to touch on. So, I'm going to start with x-ray, going through knee alignment, typical osteoarthritis, knee effusions, and some osteodysacans images, and then jump into MRI imaging of meniscus tears, insufficiency fractures, and ACL and PCL fractures. So, starting with the x-ray, one thing that I want to get out there as a message is that don't underestimate the amount of information we can gather from x-ray. We often use it mostly to evaluate for osteoarthritis, but we can also use it to evaluate for osteoarthritis. One such is the lateral x-ray view here, where the normal lateral x-ray view is in the center. The left image, you can see patella alta, which can be seen in the upper left-hand corner. On the right-hand side is an image of patella baja, so it is patella in the lower right-hand corner. And, again, we can use it to evaluate for osteoarthritis. On the right-hand side is an image of patella baja, so it is below the typical sitting position of the patella, as referenced to the center image. The merchant or sunrise view is particularly helpful to evaluate for the alignment of the patella with either a medial or lateral tilt. That can indicate either having patellofemoral syndrome or propensity towards that, patellar subluxations or dislocation events. And, also, just one thing I wanted to mention was there is the TTTG or tibial tuberosity to trochlear groove measurement, which is usually done not on x-ray but CAT scan or MRI to determine the severity of lateral patellar tilt. I won't go into details with that because that is a whole other topic. But the normal alignment you'll see is the top image with the patella centered right in the middle of the trochlear groove. On the bottom left is a medial tilt. The center image is a lateral tilt of the same knee. The most right image is actually the opposite knee, a left knee with a lateral tilt. So it's good to be familiar with what both right and left look like and get used to those images. Moving on to the most common findings with knee x-ray, which is osteoarthritis. Just a reminder that the Kellgren-Lawrence grading system is the most common grading system that we use to define osteoarthritis. And grade one, we will see joint space narrowing, which we see on the medial side of the knee joint there. Grade two, you will start to see the osteophyte formations off the ends of the bones. Grade three may see everything more severely, plus some subchondral sclerosis, which is the hyper-intense signal there, or hyper-opaque signal on the x-ray at the weight-bearing surfaces. And with grade four, everything is just more markedly severe and possible formation of subchondral cysts. And this is our polling question here. And the question is, what does this radiograph indicate? This is a lateral view. Take a good look at this x-ray image. When we get to the polling question, the image will disappear. But the options are, this is a normal radiograph, quadriceps tendon rupture, patellar tendon rupture, or intra-articular fracture. So we'll head to the polling question next. And if you can enter your answer in, I will wait about 20 seconds or so. All right I'm going to look at the polling questions which the majority believe it's a patellar tendon rupture and I will get to the answer after I speak a little bit about joint diffusions here. So here again the lateral view gives us a good view of some important structures including we see the patella here with the quadriceps tendon attaching to it. This is a normal view on the right hand side. You'll be able to identify the fat pads, the prepatellar and pre-femoral fat pads and in between is a super patellar space or super patellar space and you want a nice crisp border behind the quad tendon. On the left hand side that is an example of a joint diffusion where that space is pretty much obliterated with kind of a haziness with the joint diffusion. Moving on to the original question, this is actually a lipohemothorosis where there is not only an effusion where that more hazy opaque fluid level is on the bottom and the darker radiolucent area is actually a fatty fluid where the bone marrow has actually leaked through from an intra-articular fracture. So what we're looking at is a fat fluid level here that is apparent that indicates there is an intra-articular fracture from bone marrow. And just briefly as Dr. Olofsson mentioned this is a notch or tunnel view and this is particularly helpful to bring out osteochondritis disecam lesions. That is to bring out the particular femoral condyles a bit better. The left hand side you will see a osteochondritis disecam lesion off of the medial femoral condyle at the lateral aspect of it whereas on the right hand side that is a typical AP which will hide that that little area in the other bony shadowing. And just moving on to knee MRI I'm going to start with meniscus tears and I just want to remind everybody of the different types of meniscus tears that people can have. Depending on the type will determine the severity and how much clinical relevance there is to what we are seeing on the MRI. Typically tears that articulate with the inferior or superior surface may become more problems then. And then also be aware of the two-slice rule where if we see on an MRI image if there are two slices that we can see an MRI signal of a tear on rather than one that increases the specificity that there is a tear significantly from about 18 to 55 percent up to 90 to 96 percent. And that is meaning two slices they can be contiguous or non-contiguous meaning they can be two different slices on two different sequences. And just briefly going through meniscus pathology here are examples of the horizontal meniscus tear. Left hand side is a coronal view there with that bright signal indicating the tear. The right side is a sagittal view that also demonstrates a horizontal meniscus tear. Radial tears are demonstrated here on these images. Again the left-hand side is a coronal view and the radial tear is an oblique fashion. And the right-hand side is a sagittal view where you may see a radial tear also at an oblique angle. Bucket-handled tears are some of the more confusing ones to be able to decipher on an MRI. There are a few different signs that you can look for and starting with the most left-hand side that one is the absent bowtie sign where the typical black triangle that you see on a sagittal view in this view is just obliterated. You don't see any of that because it has flipped to another part of the knee. The second view from the left is there is the bucket handle fragment in the middle of the intercondylar notch and that is also a sign of a bucket handle. The third view is you can see a double PCL sign in a sagittal view. So the PCL is in the posterior aspect and then just underneath it you see a similar looking structure that is the bucket handle fragment. The most right-hand view is the double anterior horn sign where the meniscus has flipped and you see both triangles in the anterior aspect. And moving on to fractures on MRI. These are examples of insufficiency fractures that you will see. You do want to look at both the T2 or the fluid sensitive and T1 views to be able to compare one to the other and to confirm these fractures. The most left-hand view there is a tibial insufficiency fracture at the tibial plateau and you will see hyper intensity within the bone. In the middle picture this is the same fracture on a T1 view where the fractured area is a hypo intense region and the fracture line you usually can only see on the T1 view with the dark line indicating a true fracture. On the right hand image this is just an example of a different fracture at the femoral condyle. And then showing the pathology with ACL tears. Again on the left hand of the screen is a normal ACL with a typical somewhat heterogeneic intensity of the ACL. And in the middle picture you'll see that that ACL ligament is completely obliterated and with high intensity of the soft tissue around it. And also what to look for with ACL tears on MRI is a bone contusion pattern where with the injury the tibia will have to translate forward and knock into the anterior femur and then come back. So if you see a bone edema pattern of the posterior tibia and anterior femur be highly suspicious of an ACL tear because usually that has to tear to be able to have that bone edema pattern. And moving on to the PCL tears. On the left hand side again this is a normal PCL view with a hypo intense dark view of the ligament. And on the right hand side you'll see that there is a change in the signal. It is no longer dark and is heterogeneic in intensity and higher brightness and intensity with discontinuation. So this is just an example of what a PCL tear sorry about the labeling is a PCL tear. And that is all I have to go over for now given the time constraints. And so I will open it up to the Q&A for what time we have left. Hi everyone thank you Dr. Yao for that awesome presentation. I just want to give a huge thank you to all of my other presenters. Sorry everyone that we ran over time. It's a lot of material to fit in just one hour and I and I know when we originally planned this presentation it was for an hour and a half when we're gonna be live in San Diego. So apologies just also wanted to let everyone know that all of our slide decks are available in the handout which is that folder icon on the bottom. Hopefully this was helpful for everybody and hopefully we can do something like this again next year live especially if it was so helpful. So thank you everyone and thank you for joining us and hopefully see you guys live next time.

AAPMNR 2020

virtual session

interpretation

musculoskeletal radiology

shoulder x-rays

knee x-rays

MRIs

views and sequences

shoulder pathologies

knee pathologies