Interactive Transcript
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I'm here to talk about wrist sequences.
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I'm starting out on the far left with
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the Garden Variety T1 spin echo image.
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No, not proton density with a long TR and
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a short TE, but a short TR and a short TE.
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What is a short TR?
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A short TR, repetition time,
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is anything under a thousand.
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Preferably around 800 for high
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field and 300 or 400 for low field.
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The T1 weighted image is the idiot savant sequence.
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Any idiot can do it.
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And I don't mean people idiots.
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I mean scan idiots.
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Technologically, any MRI should be able to
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produce a high quality T1 spin echo image.
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It's the guts of any musculoskeletal study
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in MRI because it shows the basic anatomy.
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Like you would expect on an x-ray.
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And it has, as we'll see later on, some other important
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supplementary tools that augment your diagnosis.
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It gives you the relationships of bones to one another.
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It can show and characterize bone lesions.
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It can demonstrate, although it's
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not its optimal use, chondromalacia.
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And finally, it can show you bone structure,
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soft tissue abnormalities or masses
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and help you characterize them.
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The T1 weighted image is the basic frame of your
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car, but it doesn't necessarily run the car.
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What runs the car and what gives you the kind
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of detail you need to see what's under the
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hood and identify it is this middle sequence.
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The proton density, long TR, short
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TE, fat suppression sequence.
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This is the guts.
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Of every musculoskeletal MRI you'll ever do.
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Now this is the idiot savant sequence for radiologists.
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It's basically a bone scan.
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You're looking for high signal intensity
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areas, just like in nuclear medicine,
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where you're looking for hot spots.
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You may not know what they are,
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but you know that they're there.
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So you search for the hottest area, or
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most hyperintense area on the image.
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Now this scan is relatively normal, but
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here would be an example of a bright spot.
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That's simply a little capsular swelling from friction.
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The proton density, fat suppression
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sequence, at high field we call it proton
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density spare, or special, or spur.
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At low field we simply call it spur.
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And then on the far right, in the coronal
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projection, we have the gradient echo image.
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Usually acquired as a 3D, thinner section slice
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image, usually about 1 to 2 millimeters at most.
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And its strength is in looking at the relationship
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between bones in the intra-articular space.
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And it does a pretty good job at seeing ligaments too,
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like the scapholunate and lunotriquetral ligament.
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But its real strength is in looking at
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this brightish area around the scaphoid,
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which is around all the bones, by the way.
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Representing capsule, synovium,
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and normal hyaline cartilage.
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Between these two structures is a gap.
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And sometimes you'll see it as a thin
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little line on gradient echo imaging.
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That is the capsular apposition
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between two bony structures.
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That line may separate, or get wider, or fill
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with fluid, if there's capsulitis, or an effusion.
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So this gradient echo sequence, Arto centric.
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It also has another area of tremendous strength.
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You know it from other parts of the body like the knee.
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It is a great cartilage sequence, and I
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don't just mean hyaline cartilage, I mean hyaline
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and fibrocartilage like tissues, such as
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the triangular disc shape, fibrocartilage.
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It is the sequence supplemented by
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the proton density, fat suppression
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for assessing this structure.
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Not the attachments so much, although it helps
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there too, as in the peripheral attachments, but
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intrinsically, what's going on with this cartilage,
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the fibrocartilage, and the hyaline cartilage distal
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to it, and the hyaline cartilage proximal to it.
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It is not a coincidence that I put up three
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coronal projections to start you off, because
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that's what I would do if I was reading.
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I'd put up the T1, the PD spur, and the 3D gradient
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echo and I'd toggle and scroll them together for bone
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anatomy, for ligaments, for articular cartilage, for
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fibrocartilage, for soft tissue masses, and so on.
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This is like the AP projection of the wrist.
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It's comfortable and you see all of the
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bones of the wrist in almost all on slice.
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100 00:05:28,280 --> 00:05:28,810
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102 00:05:30,859 --> 00:05:31,719 The coronal.
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T1.
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PD spur spare or special.
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3D gradient echo.
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That's how I start to read with my three sequences.
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