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<v ->Now in the literature,

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you'll see a lot of disease associations,

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diseases that are associated with

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calcium pyrophosphate deposition.

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I list some of them here.

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The ones in yellow, the evidence is more significant

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that they are associated with pyrophosphate deposition.

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I show you one of these, this is hemochromatosis,

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it too produces chondrocalcinosis.

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It too affects the metacarpophalangeal joints,

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but as opposed to idiopathic pyrophosphate disease,

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not only are the second and third involved

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but the fourth and fifth may be involved as well.

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And note the characteristic hooked-like osteophytes

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on the radial aspect of the metacarpal heads,

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characteristic of hemachromatosis.

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Another example, similar finding shown by plain film and MR.

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Note the two images at the top of this slide

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showing you the hook-like osteophytes

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on the radial aspect of the metacarpal heads.

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We look at the steps that occur.

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The crystals are deposited

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in hyaline cartilage and fibrocartilage.

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I show that with the black dots.

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Here's what that would look like on MR,

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involving articular cartilage, typically mid zone

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but also fibrocartilage.

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But these crystals are also deposited in ligaments.

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Let's look at this wrist.

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Here is pyrophosphate deposition

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within the triangular fibrocartilage,

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but note the involvement of the scapholunate here

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and lunotriquetral interosseous ligament.

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And I would emphasize this particular site.

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Sometimes it's the only site of calcification

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related to calcium pyrophosphate disease.

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Elsewheres, as we turn to the spine,

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the transverse ligament of the atlas may be involved

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as shown in these images.

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And indeed, enlargement of that ligament

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and involvement with synovial proliferation

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in the posterior median atlanto-axial joint

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leads to narrowing of the spinal canal.

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These are pyrophosphate crystals.

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Rheumatologists know this well,

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they call this the crowned dens appearance.

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'Cause it looks like the odontoid is wearing a crown

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representing the calcified pyrophosphate crystals.

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Widespread involvement in the spine is less common

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but here's an example showing you with all of these arrows

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involvement not only of the transverse ligament of the atlas

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but of the discs, of posterior ligaments as well.

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of joints posteriorly, that is, the facet joints.

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You can see examples of this.

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And then finally, consider the fact that you may get

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soft tissue deposits of pyrophosphate.

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This is known as tophaceous pseudogout.

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It's a very difficult diagnosis to make.

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It can be, in fact, mistaken for gouty tophi

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that have calcified.

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This is one proven example here, shown by the arrows,

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a mass like deposition of pyrophosphate

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along the posterior aspect of the knee joint.

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Similarly here, tophaceous pseudogout

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involving the dorsal aspect of the wrist.

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Note again, predominant low signal

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and inhomogeneous enhancement

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following intravenous gadolinium.