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In the last five or seven to 10 minutes,

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we're gonna just cover a few other disorders that involve

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the, uh, sacroiliac joint and gout.

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Now, gout rarely is the only, uh,

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only involves the sacroiliac region,

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but occasionally you will see examples in which involvement

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of the spine or sacroiliac joint dominates.

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In the cases that I have seen

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with extensive gouty involvement of the sacroiliac joint,

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changes have been bilateral symmetrical or asymmetrical.

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Here's an example of gout

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with bilateral symmetrical abnormalities involving

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the sacroiliac joint.

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And note the tophaceous involvement of the cervical spine

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shown by CT and MR

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and the dominant signal intensity here that we see

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is usually low signal intensity, even

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on fluid sensitive sequences,

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although I'm not showing you such a

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sequence in this example.

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One further example of gout unusual with involvement

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of the upper cervical spine in some ways resembling

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rheumatoid arthritis

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with extensive erosion involving the odontoid process.

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When we study this with T one

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and fluid sensitive sequence, dominant low signal

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classic feature of gout,

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rheumatoid arthritis rarely

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is extensive in the sacroiliac joint.

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And in fact, it's unusual

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to see significant sacroiliac joint abnormalities there.

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When you see them, the dominant

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distribution is asymmetrical.

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So when a patient with rheumatoid arthritis presents

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with lower back pain, one of the things

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that I'd be concerned about,

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and I'll talk more about that, uh, a little bit later today,

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are these fractures

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and these are insufficiency type of, uh, stress fractures.

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They may be seen in the sacrum or the ileum

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or in both bones.

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They're said to favor the outer portions

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of the sacrum sometimes

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with transverse fracture lines as well.

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So on a, uh, a bone scan,

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it may look like the capital letter H as you can see here

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and on mr, they can be a little bit tricky.

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Sometimes they resemble diffuse involvement of the sacrum,

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as you might see with metastatic disease or a bone tumor.

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I think I'm gonna show you another example here.

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It's an old case. The images are not very pretty,

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but you can see here the sclerosis

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dominating at the periphery of the sacrum on Mr.

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Low signal and then on fluid sensitive, high signal

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dominating in the outer aspect of the sacrum.

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And one further example here, that's why I prefer ct.

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I think the features are better shown on CT than they

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are on mr.

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So in rheumatoid, please think of

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insufficiency fractures involving the sacrum

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or other regions of the pelvis.