There are three major imaging planes in the shoulder protocol in MRI, axial, oblique coronal, oblique sagittal. The only time an ABER type sequence is obtained is in the setting of an orthographic study, so ABER being abduction external rotation, essentially the technologist places the hand of the patient behind their head and then re-does the coil over the shoulder and then obtains the images. I have some examples of that later. So to obtain, to prescribe the oblique coronal sequence, typically the techs are asked to make it parallel to the supraspinatus muscle on an axial image. Really what they're trying to do is make the slices perpendicular to the face of the glenoid. And then the oblique sagittal is perpendicular to that, i.e. parallel to the face of the glenoid. And with different inclinations of the glenoid then, it becomes more and more important for the enlightened technologists to take that into account so that in the setting of glenoid bone loss, you can evaluate the antero-inferior glenoid rim. The radiologists tend to not understand the coracoacromial arch very well and don't really focus on it and miss a lot of stuff. So you'll have to look there yourself. The oblique sagittal images are great for the coracoacromial arch. So here's the acromion and the clavo coming together to form the AC joint. You can see its relationship to the supraspinatus muscle. Here's biceps tendon, overlying rotator interval. And so in the setting of adhesive capsulitis, it's in this area where you expect to see most of the abnormal soft tissue thickening that can correlate clinically with a painful decrease in range of motion. The images show very well the coracoid here and then this coracoacromial ligament and again its relationship to the underlying supraspinatus muscle. So here is oblique sagittal images that show this apparent AC joint. But then here's the other AC joint. So this is a person with an osteochromiality and a pseudarthrosis, a potential pain generator that again radiologists tend not to notice. This is an example of a normal cuff tendon followed down to the greater tuberosity attachment site on an oblique coronal image. But the abnormality here is really related to the AC joint, tremendous bone marrow edema on both sides of the AC joint, acromion, clavicle, and erosion here. So distal clavicular osteolysis with a boatload of bone marrow edema and capsulitis. Normal rotator cuff. So here's an individual who's fallen, has normal AC joint alignment. And here is the MR image in the oblique coronal plane and here's the normal alignment but all this edema that's surrounding and extending up into the trap. On the oblique coronal images, here is the acromion, here is the distal clavicle. What does this black line represent? The capsule's not well seen, so likely a tear. And this is a subperiosteal hematoma or fluid collection. And it's important in that setting to come back and look at the coraco-clavicular ligament complex which is always present on the oblique sagittal and coronal images. And in this case, it's more or less intact. There's some partial tear, so sort of an intermediate AC joint strain. Here on the other hand is an abnormal AC joint alignment. And the capsule isn't well seen. This is not an acute, it's more of a subacute setting because a lot of the surrounding edema and inflammation and hemorrhage is resolved. But on these oblique coronal images, you come anterior following the clavicle, normal cuff tendon again. So an abnormality that's strictly speaking related to the coraco-acromial arch. The CA ligaments, CC ligaments here, coraco-clavicular, yeah, CC ligaments here are not well seen. So a much more high-grade AC joint injury. So there are really just two major criteria in the evaluation, in the conclusion that there's a rotator cuff tear. One is tendon retraction and the other is fluidless crossing the full thickness of the tendon. So to evaluate the cuff, identify on the oblique coronal images the biceps tendon and biceps tendon groove. And then one slice posterior to that, or two, will be the anterior margin of the greater tuberosity, the leading edge of the supraspinatus tendon where attrition-related, age-related tears tend to begin. And if you are looking at the images from back to front, from infra to supra, then you are more likely to see a transition from normal to abnormal and identify the smaller rotator cuff tears. This is a normal cuff tendon. Why is that increased in signal intensity right there? So it's black, gray, black, because this is an artifact called magic angle phenomenon. And so it's at a certain angle, 55 degrees, to the main magnetic field. So don't be confused by this artifact. Classical small rotator cuff tear. Proton density and T2-weighted fat-suppressed images are what you're mostly going to be looking at in these protocols. So bursal-sided fibers identify them. Articular-sided fibers identify them as well. And in this case, there is this full-thickness column indicating full-thickness cuff tear. So from back to front, here is an intact tendon. Come forward one more slice, okay, there's a defect here. Now we see this transition from normal tendon to full-thickness cuff tear with some bursal fluid extending across the tendon and into the joint space. Full-thickness tears, well, it's disruption of articular or bursal-sided fibers. So in this case, the articular-sided fibers can be followed down. The bursal-sided fibers are disrupted with this focal fluid within the tendon substance and some adjacent bone marrow edema. It can be difficult differentiating the subtotal tear, you know, the near-complete tear from a high-grade partial. Maybe it doesn't matter. So this is the way that cuff tendon looked at bursoscopy or arthroscopy, where the burses here, these are the retracted bursal-sided fibers, the intact articular-sided fibers at the greater tuberosity attachment site. Here's a tennis player, and I'll point out here some fluid that is within the substance of infraspinatus. So a finding that can be associated with tendon delamination, separation of articular and bursal-sided fibers. Now as we come more anterior, there's some thickening of the tendon. Most radiologists would call this tendinopathy or tendinosis. But then what happens right here? We're into supraspinatus, and there is this focal fluid. And it can be very difficult to determine whether or not there's a perforation here involving either or both articular or bursal-sided fibers, or whether this is all intrasubstance. And notice that there's no bursal fluid and no joint fluid, but there's a lot of fluid inside the tendon. This is what the surgeon dictated. Good visualization of the rotator cuff was achieved. There was no full thickness rotator cuff tear, nor was there even any high-grade partial thickness tearing, either intraarticularly or subacromially. Therefore no rotator cuff repair was performed. So I can tell you this is a failure of communication on the part of the radiologist. And it could have been me for that matter. But instead of, I think there should have been an indication that this focal fluid could be intrasubstance and therefore represent a concealed high-grade partial tear to alert the surgeon, you, to the possibility of, well, a concealed tear. So prognostic factors in rotator cuff tear. Muscle atrophy, the quality of the tendon, especially delamination, and then maybe the shape of the tear as well, U versus L. Let's look at some of those things. So this is a person who's had a recent fall. And notice that the infraspinatus tendon here is very thickened and irregular in contour, consistent with a lack of organization and remodeling that you would expect to see in a remote tear. And infraspinatus is pulled off, more anteriorly, supraspinatus is pulled off, abnormal glenohumeral alignment. So this person goes on to a cuff repair. This is the oblique sagittal. The oblique sagittal images are by far going to be your go-to sequence for assessing comparative muscle atrophy and fatty replacement. So supra here, infra here, and there's only a mild degree of fatty change relative to teres minor. So now the patient doesn't do well, eight months following the cuff repair, and comes in and still has this retracted infraspinatus, retracted supraspinatus, abnormal glenohumeral alignment. Now there's quite a bit of cartilage loss and this artifact from the cuff repair. Now how much muscle atrophy is there? So it's more, let's call it moderate. Another cuff repair, but the patient's not doing well. There's much more metal artifact now, abnormal alignment, retracted tendon, and now it's a severe degree of muscle atrophy. So the point in this case is I wanted to demonstrate this progression, expected progression of fatty atrophy, supra and infra, from mild to severe over time. Subscap isn't doing so well either in this case. So now I have an example of U-shaped and L-shaped teres. So more posteriorly, this is an orthographic study, here is infraspinatus, followed down to the greater tuberosity attachment site. And as I come from posterior to anterior now, we're starting to see some supraspinatus fibers and notice the asymmetric degree of retraction. So bursal-sided fibers here, articular-sided fibers there. This asymmetric retraction indicates to me that there's been tendon delamination. As I continue more anteriorly, the cuff tear seems to decrease in size and then just posterior to the biceps tendon groove, supraspinatus reattaches to greater tuberosity. So these are the typical findings for a U-shaped tear in contrast to this example where infraspinatus is intact. And I come more anteriorly, this is residual infraspinatus, but supraspinatus is way retracted. There's a degree of tendon delamination as well, bursal versus articular-sided fibers. But the supraspinatus never comes back down to the greater tuberosity. And you can follow this retracted tear all the way to the biceps tendon groove and the region of the rotator interval. Sagittal images I think do a great job with characterization of U versus L. And then here is supraspinatus, coracoid process, biceps tendon, and then right here is this defect between the fibers of the rotator interval and supraspinatus and then no supraspinatus down to the greater tuberosity. Ball-shaped tear. Okay, let's turn our attention now to the labrum and glenohumeral instability and start off by looking at these arthrographic images. Superior labrum, superior glenohumeral ligament conjoined with middle glenohumeral ligament. So here's middle coming down, merging with subscap. And this is a normal anterosuperior variant, you could call it a sublabral sulcus or foramen. But it's normal, it's not a labral tear in this particular location. And articular cartilage partially undercutting posterior labrum, anterior labrum, no normal sulcus antero inferiorly, and then this is the IGL. So the IGL is wrapping around, attaching to the labrum. It's in this location where labral tears may be most closely associated with glenohumeral instability. Okay, this is an ABER image obtained because it's an arthrographic study and it shows the humerus where the IGL is attaching to the humerus and then on a single slice you can follow it back to the labrum partially undercut by articular cartilage but no displacement of the labrum from the glenoid rim, normal labral ligamentous complex. In confident diagnosis of labral tears you're looking for displacement of the labrum from the glenoid rim, also perhaps sublabral fluid and then the paralabral cyst as Tom mentioned. So here is a normal cuff tendon and the biceps tendon at the superior glenotubercle attachment site and here the labral-bicipital anchor looks fine but what happens is we go more posterior. Okay so there's some high signal between the labrum and the glenoid rim. Maybe you could call this a small paralabral cyst as well. In any case, these findings meet the criteria for a labral tear, in this case posterosuperior in location, small paralabral cyst. 22-year-old weakness, actually Tom you might remember this case. We can see the anterior labrum and actually let me point out this cyst right here. So this is an orthographic study, T1 weighted fat suppressed, T2 weighted fat suppressed and then here in the suprascapular notch is this cyst. Let's follow this cyst, that's the suprascapular artery and then the cyst comes down. So on this image notice that the posterior labrum looks okay, slightly irregular in contour but no displacement from the glenoid rim. It's an orthographic study, we're seeing contrast undercutting the labrum and then coming into this cystic structure which is located here. So if this wasn't an orthographic study and you saw this paralabral cyst then you could conclude with confidence that in fact there is a labral tear but because this is an orthographic study we're also seeing contrast undercutting the labrum. So the paralabral cyst is pathognomonic for an adjacent labral tear. I also just want to point out that in this particular case because the cyst is going all the way into the suprascapular notch it's really probably an intraneural ganglion, a variant of a paralabral cyst. And because the cyst is heading all the way to the suprascapular notch then you might expect to see supra as well as infraspinatus denervation findings. So in this case notice the slight increase in signal intensity of both supra and infraspinatus due to this denervation phenomenon in the absence of substantial muscle atrophy. That comes next. Acute dislocation. These are the classical findings. In this case a minimally depressed heel-sax fracture with bone marrow edema. So you know there's been a dislocation. So that means that you focus your attention at the anterior and anteroinferior glenoid rim. So here at this level the labrum is normal. And as we head more anteroinferiorly this is a Bankart lesion. As I go a little bit more distal this little nubbin represents the IGL and it could be followed back to this labral tear. Therefore the IGL is attached to a labrum that's not normally attached to the glenoid rim or underlying articular cartilage. Findings that may be closely associated with glenohumeral instability. Here in the acute setting in the setting of an avulsion of the glenohumeral ligament from the humerus you can expect to see this discontinuity edema and hemorrhage extending into the neurovascular bundle. This posterior humeral circumflex neurovascular bundle. And then also into the region of the brachial plexus as well which is more closely associated with anorepraxia. But in the non-acute setting then all this scars down and it's really impossible by MRI to be confident about an avulsion of the ligament off the humerus. So it's only in the acute setting where you can see these findings. So what are the expected findings in the setting of chronic instability with or without a previous history of dislocation? So this example here we start off with an arthrographic MRI. So clearly the clinical diagnosis is glenohumeral instability. What are the imaging findings? So we're focusing on the anterior labrum here and there's this very subtle increase in signal intensity. There's a cyst here and posteroinferiorly also a labral tear. So a very, very subtle anteroinferior labral tear. This is the ABR. So this is the IGL coming back to the labrum and now in the ABR where tension is transmitted through the IGL back to the labrum there is some displacement away from the glenoid rim. So findings that may be associated with glenohumeral instability. The patient opts not to have surgery. Twenty months later, now let's compare the baseline study with a 20-month follow-up. So what's this right here? It's not the IGL. I'm sorry, the MGL. It's not the MGL because we can follow it down to where the IGL should be located. So this is the anterior labrum that's now wildly displaced away from the glenoid rim. So this and that are the same thing. So this is progressive glenohumeral instability in a person now with this very large Bankart lesion. So this is the labrum. Now it's here. It's very thick. There's adjacent cartilage defect now. Posteriorly the cyst and the labrum look the same. And then here on the ABR images, the labrum is thickened. The degree of displacement is increased and the degree of instability is increased and now there's a cartilage defect here where there was not before. So the natural history of an athlete with glenohumeral instability. So this is an example to be an example of multidirectional instability. So based on clinical evaluation and then here what does the corresponding MRI show? Labrum, periosteal stripping, same thing posteriorly. Labrum undercut, small paralabral cyst maybe, but periosteal stripping posterior capsule along the glenoid rim. And those findings, here's a cartilage lamination as well, focal cartilage defect, periosteal stripping. So anterior as well as posterior multidirectional instability. And you might call this a Perthes lesion if you're into those kinds of terms because the IGL is followed down to the labrum. That's not really displaced so much, but it is undercut by contrast material with periosteal stripping, capsular stripping along the medial glenoid neck. So at least two previous dislocations. Here's the Hill-Sacks fracture, orthographic study, labrum displaced from glenoid rim. But then you can follow it down to where it's reattached here and all glommed down and medialized and glommed down to the glenoid. So the classic ALPS lesion here on ABER. IGL followed down to labrum, labrum is complex, displaced medially and scarred down to the glenoid rim. Not in its normal location. Findings that are closely associated with instability. And then finally, this is the last case, and Tom, you'll remember this case as well. So it's an NFL player. Let me just shoot down here. You can see he's already had a stabilization procedure and some anchor sites in the glenoid. What else is going on? Well, he has this fracture fragment. And so superimposed on the glenoid defect and the post-operative changes related to the stabilization procedure is this glenoid rim fracture. Reformats, notice this is a CT, not an MRI, because the assessment is for the purposes of bone stock in the glenoid. And the decision about Latter-Jay versus non-Latter-Jay repair. So here is that bone fragment. This is a great use for CT, non-arthrographic CT, because then you can obtain these 3D images. And I think there is some controversy in the literature, but more and more often it's concluded that the 3D images are better than the 2D reformats for assessing glenoid rim defects and making decisions about Latter-Jay versus soft tissue repairs. And this person went on to a Latter-Jay and his career was done. And with that I'll conclude, and I hope everyone has a safe trip home.

imaging planes

MRI shoulder protocols

ABER sequence

glenoid bone loss

Coracoacromial arch

rotator cuff tears