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On this patient, he's 29 years old and has

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sudden onset of pain in the shoulder, no trauma.

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We have coronal T1 weighted and coronal

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fat suppressed proton density images.

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We are going through the humeral head.

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The main finding here is the presence of a

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geographic pattern of abnormal marrow signal that is

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affecting the superior portion of the humeral head.

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And it's very clearly demarcated

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with the adjacent normal marrow.

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At the interface between this geographic zone of

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abnormal marrow signal, we see a focus of the fluid

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light signal intensity consistent with cystic change.

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So there is a cyst at the interface between

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the geographic zone of abnormal marrow.

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Now if we look attentively on the T2 weighted sequence, we

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can see that there is a dark line next to a bright line.

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This is called the double line sign.

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And it's typical of avascular necrosis.

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As radiologists, our main job is to look at the subchondral

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plate and just above the area of avascular necrosis and

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make sure that there is no indentation of the subchondral

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plate that could indicate the presence of a crescent sign,

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which is translated on radiographs linear radiolucency.

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Extending along the endosteal

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lining of the bone that is affected.

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So in this case, we see that there is a focal

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indentation here of the subchondral plane.

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There is a slight marrow edema.

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So this patient is moving from a stage two of avascular

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necrosis where there is only changing the

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marrow with geographic borders, but the subchondral

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plate is still intact to a stage where we are starting

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to see failure of the subchondral plate manifested

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by the presence of indentation and marrow edema.

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So this would be a stage three.

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In these cases, I often use A classification,

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the Ficat classification, and I go with stage 2

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3 because there is not yet a very well defined

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subarticular fracture to make it a definite stage 3.

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So to summarize, we want to identify the geographic

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pattern of abnormal marrow signal on T2 weighted sequences.

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We want to look for the double line sign,

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complications of AVN, cyst formation.

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This patient has that as an associated finding.

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And then most importantly, look for that area of

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subchondral plate indentation with associated marrow edema

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that is indicating that there is an impending AVN.

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Subchondral collapse and the patient

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may be having now pain because of that.

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So typically, avascular necrosis before the

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subchondral plate is indented and it starts

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to collapse is completely silent clinically.

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Patients don't have any symptomatology.

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Given the fact this patient is already having

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some pain, this could be a source of pain.

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Pain.

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Of course, we want to look for other

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abnormalities, rotator cuff tears.

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I don't see any rotator cuff tears in this

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patient, and there were not labral tears

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found on the evaluation of the entire study.

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So to conclude, this is the stage 2, 3 avascular

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necrosis of the humeral head as described.