Thank you, Dr. Gillen. For the final session of the course, we invite Dr. Palmer back up to cover imaging of the shoulder. All right. In these last 15 minutes or so, I'm going to address selected topics in the shoulder, focusing on the arch, the cuff, labrum, and instability. And before that, I just want to review some of the imaging planes. So there are three basic planes, axial, oblique, coronal, and sagittal. And the coronal typically is prescribed along the long axis of supraspinatus. And what the techs are actually doing, for the most part, is making the images perpendicular to the glenoid face. And then the sagittal images are going to be parallel to the glenoid face. And what you want the technologist to do, what you want to be able to see, is that the shoulder's been externally rotated. So lesser, greater, biceps. This is an appropriately externally rotated image. Aber images are typically done in the setting of an MR orthographic study. And what the technologists do is put the hand behind the head. And so the arm goes up in the air like that. And then the technologist will prescribe the images parallel to the humerus. And it generates an image like this. So we're used to seeing in the typical coronal plane a taut cuff and a loose or lax capsule. And it's the opposite in an Aber image. So here the capsule's tight back to the labrum. And now the cuff is very, very lax. This is the rotator cable. The sagittal images are great if you're interested in the structures of the coracoacromial arch. For example, here's the coracoacromial ligament. And you can see its relationship to the coracohumeral ligament, where it's passing next to supraspinatus, the relationship between the AC joint and supraspinatus. And then follow that CA ligament all the way back to the acromion, where there might be a large spur. So I'm going to start off with some cases related to the arch. And Tom showed an osacromiale. Here's one in the axial plane. Now in MR images, the osacromiale is going to be most commonly associated with symptoms when there's bone marrow edema. Proton density, fat suppressed T2. Here is a normal marrow. And already the acromion here is showing a lot of high signal due to bone marrow edema. And then here's the acromion with edema on either side of that apophysis. Same person, normal bone marrow, bone marrow edema. And then here's the physis for the osacromiale. Look for bone marrow edema to be associated with pain. And a squash player, overuse, normal cuff, no fluid in the bursa, but there is this intense amount of fluid and bone marrow edema on either side of the AC joint with some erosive changes as well. So overuse, bone marrow edema equals pain. This individual had a fall, and the radiographs show a normal acromioclavicular alignment. The MR shows normal cuff tendon and this capsular abnormality with a very prominent surrounding edema and hemorrhage. And then here on the sagittal images, T2 weighted, there's the subperiosteal hematoma, capsular disruption, lots of edema and hemorrhage. And then as we come a little bit more proximal, almost all MR images are going to include a little bit of the coracoclavicular ligament complex. Here's the trapezoid, which is not normal but is intact in a person with a grade 2. And then here's an example of a grade 3 AC separation, and the trapezoid ligament's completely shot, nothing normal about it. And in the sagittal coronal plane, conoid trapezoid not visible, we work our way back to the AC joint and then see the expected alignment abnormality in the absence of a capsule. And here's the grade 3. So it's not very common to get MR images in that setting, and so I want to differentiate what we just saw with the AC separation with this particular case where there's been no trauma. And this is a fat-depressed T2 coronal plane, bone marrow edema, the capsule doesn't look normal, there's prominent surrounding inflammation, and on the sagittal image, same sort of deal. Lots of trap and bursa, and so this is a person with a septic AC joint. And so a lot of the inflammatory changes and the capsular changes can be identical, so keep that in mind. A 35-year-old, plays lots of squash, and I want to focus on the coracoacromial ligament and then the location of this edema and inflammation. So in a true bursitis, the MR images will show the edema and inflammation between the CA ligament and the cuff tendon and the rotator interval. And the sagittal images show it very well. Here's the ligament, the interval, the biceps, here's supraspinatus, and then this very thick wad of abnormal inflamed tissue in a person with a true bursitis. And then Tom also showed some calcific bursitis, and so all these low signal foci represent extensive calcifications, and it's not uncommon for them to be associated with some sort of cuff defect, and on this image you can follow the calcification into the bursal side of the distal supraspinatus tendon. So let's move on to the cuff. Two major signs, fluid crossing the full thickness of the tendon, and then tendon retraction. Now when you're looking at the cuff or cuff tears, especially attrition-related tears, first of all identify the biceps tendon groove, because the next slice back or two slices back are going to show the supraspinatus, where these attrition-related tears tend to occur first. So here's supraspinatus, empty junction, notice the high signal right here, and then it becomes low in signal again. This is an artifact called magic angle phenomenon, and it's not reflecting any abnormality of the tendon. Some radiologists will call this tendinopathy, but it's normal. So there can be advantages, starting more posterior towards infraspinatus and working your way anterior, because infraspinatus tends to be normal in the setting of a small rotator cuff tear. And so if you do that, you're more likely to identify a transition point from normal to abnormal. So here's a normal tendon thickness, and here as well, but now, boom, you can see this disruption of the tendon right at the greater tuberosity attachment site, so there's bursal fluid, you can follow it across the full thickness of the tendon into the joint. This is a small but full thickness rotator cuff tear. Here's a slightly larger tear, and there's some degree of tendon retraction, but it's a full column of fluid with tendon retraction, and then abnormal distal tendon with some fluid coming inside the tendon itself. Partial thickness tears, you're looking for fluid that's focal and at an articular bursal surface or maybe inside the tendon. Here there is focal fluid that is followed out into the bursa, and the bursal-sided layer is retracted to a small degree with bone marrow edema. The articular fibers here are still intact, but this is a very large partial thickness tear, so it's a subtotal tear, and in that setting, this particular surgeon decided to take the patient to the OR, these being the remaining intact articular fibers. Here's a patient who has an abnormal tendon, and it's abnormal because it's too thick, and it's too high in signal intensity, and there's a little bit of delamination between the bursal and articular fibers, and as I come more anterior, there is some focal fluid that's inside the tendon, although the bursal and articular fibers look intact. So this patient, because I dictated the case and said there was a large partial thickness tear, the surgeon, and Tom certainly knows Dr. Warner, stuck it to me bad here. Good visualization of the cuff was achieved, no full thickness tear, nor was there even any high-grade partial thickness tear, either intra-articularly or subacromally, therefore no rotator cuff repair was performed. So I just want to point out this concealed tear, and it often results in a discrepancy between what a radiologist might say and what you might find at arthroscopy. Okay, a quick few things about delamination, and I see this quite frequently in full thickness and partial thickness tears, and here is an arthrographic study, and this is T1, this is T2, and for sure there's a full thickness cuff tear, and so you can follow this high signal contrast across the bursal layer out into the subacromial subdeltoid space. And so notice how attenuated this looks, and it's attenuated because these are the articular fibers. So there's been a dissociation between the bursal and articular fibers with retraction of the articular fibers. Now in this case, it's another MR arthrogram, there's no full thickness defect or leak of contrast material into the subacromial subdeltoid space, but most of the tendon is off the greater tuberosity. And so in that setting, when there's this attenuated bursal layer coming down, then take a little bit more closer look for these retracted articular-sided fibers. So it's a broad-based partial thickness articular-sided tear with delamination and fiber retraction. As we go back to infraspinatus, it's very, very abnormal and irregular in contour, and yet there's no pouch that's visible because the tendon is draped over the humeral head and the potential space created by the delamination is not visible. And so the ABER images, I think, are actually better for the rotator cuff than for the labrum. So here we're seeing, as I go from anterior to posterior on the greater tuberosity, the bursal-sided fibers here, the articular-sided fibers there, and then this huge cavity that's filled with contrast material through this defect. So it's a huge cavity due to delamination that's extending four, maybe five centimeters back along infraspinatus tendon, and then a little bit more posterior, the tendon pulls itself back together again. So extensive delamination with even large cavities may not be visible on conventional adducted images. And this case is meant to illustrate that. So a youngish individual, a great athlete, biceps tendon here, biceps tendon groove, therefore this is greater tuberosity and this is supraspinatus tendon, which looks normal. And as I head back, we're going to follow supraspinatus, a little defect here, back to infraspinatus, and I think most radiologists are going to call this just drop-dead normal tendinopathy, okay. Now on the ABER images, look what happens. So we're anterior here, here's biceps tendon, here's greater tuberosity, this is the rotator cable, so a normal structure, this is not a tear. Supraspinatus is still looking great. Now we work our way back to infraspinatus. These are the articular fibers, these are the bursal fibers, this is a large cavity extending about four centimeters along the muscle tendon junction of infraspinatus, so potential poor quality tendon due to delamination and the formation of a cavity. I'm going to shift gears now to the glenohumeral joint. In the setting of acute dislocation, within six to eight weeks, you expect to see bone marrow edema, so there's a mildly depressed Hill-Sachs fracture, biceps tendon, anterior, posterior, mildly depressed fracture with bone marrow edema. Same individual at the mid-glenoid level, this is a normal anterior labrum, and distal to the mid-glenoid level, there should be no normal sulcus. So as we extend down to the antero-inferior labrum, this is a true tear and most people would call this a non-displaced Bankart lesion or non-displaced antero-inferior labral tear. Non-arthrographic study, bone marrow edema, mildly depressed Hill-Sachs fracture, this is a gradient echo, this is a fat-depressed T2, and they both are going to show the exact same thing. So this is some MGL, and next to the labrum, which is displaced from the glenoid rim, and the MGL is branching off, and then here is the labrum, and it's undercut by fluid, and the capsule is stripped, and there is edema where the capsule is stripped away from the glenoid attachment site, and then the tear extends all the way down to the IGL attachment site. So classic anterior antero-inferior labral tear in the setting of an acute dislocation. So I threw this in during the instability talk by Dr. Bishop, just to reinforce the impaction injury and then the Hagel lesion. And so this is the IGL, and there is fluid extending from the joint down into this posterior humeral circumflex neurovascular bundle, and in the acute setting, this is an obvious Hagel lesion, but just like in the knee when those ligaments tear two, three years down the road, this is going to scar down after a couple of months and remodel, and a couple years later, if the patient's unstable, you'll never be able to see this on a conventional MR image. And even at MR arthrography, it's a very, very difficult diagnosis for the radiologist. And then I'll wrap things up with some examples of patients who have a longer standing instability. But I also wanted to show the normal glenohumeral ligaments first, and then the developmental variation of the labrum anterosuperiorly, biceps SGL. And we're coming down to MGL here, which then merges with subscap. So if I come back up to the anterosuperior level, here's normal labrum, and this is normal labrum. And this is that pesky sulcus that radiologists will often over-call as a tear. Normal posterior labrum, partially undercut by articular cartilage, that's not a problem. And then this, if it's just a normal sulcus, should pull itself back together, and the labrum should, well, be black triangular, partially undercut by cartilage, and now the sulcus is gone. And we can follow the labrum back down to this little nubbin, which represents the IGL wrapping around to attach the humerus. And so this is where the Hagel defect will occur. On the ABER images, if you're looking for a labral tear that may be associated with glenohumeral instability, you want to look right here at the IGL attachment site. So here's a person with glenohumeral instability, and there's some capsular stripping or periosteal reaction, the labrum, a piece of articular cartilage. This is the focal defect, the donor site for this articular cartilage. So this degree of displacement, the cartilage defect, and then the capsular stripping here, all classical imaging findings associated with glenohumeral instability. Here's a person who has longer-standing instability, the labrum is wildly displaced from the glenoid rim. And then here's the classic ALPS lesion, where the labral ligamentous complex is scarred down to the glenoid rim, and here as well, displaced from where it should be, the cartilage in this case looks normal. So I live to compete, here's his MR arthrogram, he has this cyst, a posterior inferior tear, and then this anterior inferior labrum, it's hard to tell if there's a tear or not, but on ABER it separates from the glenoid rim. So IGL to labrum displaced from the glenoid rim, this is a lesion without capsular stripping, this is a lesion that's closely associated with glenohumeral instability. The individual chose conservative treatment but comes back 20 months later, this is the baseline image, and then this is the 20 months later image. So now the labrum that was normally located is displaced all this distance away, now there's a focal cartilage defect, this posterior inferior labral defect is completely unchanged, as is the adjacent cyst, and on the ABER images, the labrum now is wildly displaced, and there is a cartilage defect, whereas the cartilage looked normal 20 months earlier. So sort of like the natural history of the Bankart lesion, if it's not taken care of in time. And this is the last case that I have, so this is a person who's had a Bankart repair, has this fracture fragment, this glenoid defect, and then this fracture fragment on the coronals as well. And Julie mentioned 3D images, they can't be done in the setting of an arthrogram because the contrast will mess up the 3D recon. And so they might be more valuable than the 2D because you need to have a technologist who puts the slice in the appropriate glenoid plane. But here are a bunch of suture sites or degenerative cysts, the defect, and then the circles, the lines, and the measurements can be made, and this person goes on to a Latergé. So with that then, I wish you all a safe journey home. Thank you.

imaging techniques

shoulder

axial plane

rotator cuff tears

glenohumeral instability