0:00

I'm here to talk about wrist sequences.

0:04

I'm starting out on the far left with

0:07

the Garden Variety T1 spin echo image.

0:11

No, not proton density with a long TR and

0:13

a short TE, but a short TR and a short TE.

0:18

What is a short TR?

0:19

A short TR, repetition time,

0:21

is anything under a thousand.

0:24

Preferably around 800 for high

0:26

field and 300 or 400 for low field.

0:31

The T1 weighted image is the idiot savant sequence.

0:35

Any idiot can do it.

0:38

And I don't mean people idiots.

0:40

I mean scan idiots.

0:42

Technologically, any MRI should be able to

0:45

produce a high quality T1 spin echo image.

0:51

It's the guts of any musculoskeletal study

0:55

in MRI because it shows the basic anatomy.

1:00

Like you would expect on an x-ray.

1:02

And it has, as we'll see later on, some other important

1:06

supplementary tools that augment your diagnosis.

1:11

It gives you the relationships of bones to one another.

1:15

It can show and characterize bone lesions.

1:19

It can demonstrate, although it's

1:21

not its optimal use, chondromalacia.

1:26

And finally, it can show you bone structure,

1:27

soft tissue abnormalities or masses

1:30

and help you characterize them.

1:32

The T1 weighted image is the basic frame of your

1:36

car, but it doesn't necessarily run the car.

1:41

What runs the car and what gives you the kind

1:44

of detail you need to see what's under the

1:46

hood and identify it is this middle sequence.

1:51

The proton density, long TR, short

1:54

TE, fat suppression sequence.

1:57

This is the guts.

1:59

Of every musculoskeletal MRI you'll ever do.

2:03

Now this is the idiot savant sequence for radiologists.

2:08

It's basically a bone scan.

2:11

You're looking for high signal intensity

2:14

areas, just like in nuclear medicine,

2:17

where you're looking for hot spots.

2:19

You may not know what they are,

2:22

but you know that they're there.

2:24

So you search for the hottest area, or

2:28

most hyperintense area on the image.

2:31

Now this scan is relatively normal, but

2:33

here would be an example of a bright spot.

2:36

That's simply a little capsular swelling from friction.

2:41

The proton density, fat suppression

2:44

sequence, at high field we call it proton

2:46

density spare, or special, or spur.

2:50

At low field we simply call it spur.

2:54

And then on the far right, in the coronal

2:57

projection, we have the gradient echo image.

3:00

Usually acquired as a 3D, thinner section slice

3:04

image, usually about 1 to 2 millimeters at most.

3:10

And its strength is in looking at the relationship

3:13

between bones in the intra-articular space.

3:16

And it does a pretty good job at seeing ligaments too,

3:19

like the scapholunate and lunotriquetral ligament.

3:23

But its real strength is in looking at

3:25

this brightish area around the scaphoid,

3:29

which is around all the bones, by the way.

3:31

Representing capsule, synovium,

3:35

and normal hyaline cartilage.

3:38

Between these two structures is a gap.

3:41

And sometimes you'll see it as a thin

3:43

little line on gradient echo imaging.

3:45

That is the capsular apposition

3:48

between two bony structures.

3:51

That line may separate, or get wider, or fill

3:54

with fluid, if there's capsulitis, or an effusion.

3:58

So this gradient echo sequence, Arto centric.

4:02

It also has another area of tremendous strength.

4:07

You know it from other parts of the body like the knee.

4:12

It is a great cartilage sequence, and I

4:15

don't just mean hyaline cartilage, I mean hyaline

4:18

and fibrocartilage like tissues, such as

4:22

the triangular disc shape, fibrocartilage.

4:27

It is the sequence supplemented by

4:31

the proton density, fat suppression

4:34

for assessing this structure.

4:36

Not the attachments so much, although it helps

4:39

there too, as in the peripheral attachments, but

4:41

intrinsically, what's going on with this cartilage,

4:44

the fibrocartilage, and the hyaline cartilage distal

4:47

to it, and the hyaline cartilage proximal to it.

4:51

It is not a coincidence that I put up three

4:55

coronal projections to start you off, because

4:58

that's what I would do if I was reading.

5:01

I'd put up the T1, the PD spur, and the 3D gradient

5:05

echo and I'd toggle and scroll them together for bone

5:09

anatomy, for ligaments, for articular cartilage, for

5:13

fibrocartilage, for soft tissue masses, and so on.

5:18

This is like the AP projection of the wrist.

5:21

It's comfortable and you see all of the

5:25

bones of the wrist in almost all on slice.

5:27

100 00:05:28,280 --> 00:05:28,810

5:28

102 00:05:30,859 --> 00:05:31,719 The coronal.

5:32

T1.

5:34

PD spur spare or special.

5:36

3D gradient echo.

5:37

That's how I start to read with my three sequences.