0:00

Let's introduce how we do it, foot and

0:04

ankle MRI, beginning with the coils.

0:07

Most of you have a knee coil.

0:09

So the knee coil and even the head coil

0:13

can serve as a substitute for a foot coil.

0:17

But nothing works like something that was

0:19

intended to perform a specific function.

0:23

And so if you're going to do a lot of feet,

0:25

you probably ought to invest in a foot coil.

0:28

If you have a coil with an opening like this,

0:31

the advantage is that you've got a smaller

0:34

field of view around the midfoot and the

0:36

ankle, but you're also not imaging the toes.

0:39

If you're going to image the toes in a

0:41

coil like this, then clearly you have to

0:44

plantar flex the foot, or turn the patient

0:47

over on their stomach and have the foot

0:50

plantar flexed so the hole fits in the coil.

0:54

You'll see in a few moments that that has a

0:56

distinct advantage of making imaging of the

0:59

tendons far superior than having the foot in

1:02

a neutral or somewhat dorsiflexed position.

1:06

On the other hand, this position is

1:08

more advantageous than when you're

1:10

looking at the collateral ligaments.

1:13

When we go over here we have a

1:15

dedicated coil that includes the toes.

1:20

This is terrific because now you've got the entire

1:24

hindfoot, midfoot, and forefoot in the coil.

1:26

But at the same time you're also

1:28

limited in the amount of plantar flexion

1:31

that you can perform the study in.

1:34

Which means that you may be hampered a

1:37

little bit in your assessment of tendons.

1:40

And we'll see.

1:41

Why?

1:41

That is, in a moment.

1:43

So then we have a third option.

1:45

Flexible coils.

1:47

And those coils can be placed on either

1:49

side of the ankle, medial malleolus,

1:53

lateral malleolus, or in front or in back.

1:57

So extensor and flexor regions,

1:59

depending upon your area of interest.

2:03

The beauty of these coils is they can

2:04

be moved around, from the hindfoot,

2:07

to the midfoot, to even the forefoot.

2:10

There's another set of coils that I don't

2:12

have depicted in here. But I will depict

2:14

for you when we get into our discussion of

2:17

toes, turf toe, and the great ankle, and

2:20

those are the beloved microscopy coils.

2:23

Where you can get fields of view down

2:25

to around 4, or 6, or 8, and 100 microns

2:29

of in-plane special spatial resolution.

2:32

And that will be a story for another day.

2:36

So I've shown you three different coils, two

2:40

rigid, one soft. Alluded to the microscopy coil

2:46

for the toe, and then also included the fact

2:49

that the head coil and the knee coil, especially

2:52

the pediatric head coil, are also available to

2:55

you as potential imaging tools for the foot

2:59

and ankle, but positioning is going to be a

3:03

tantamount importance in these coils and your

3:06

technologist, as well as the physician teaching

3:10

and orchestrating the study

3:12

through the technologist's eyes.

3:14

It's going to be critical in deciding whether the

3:16

foot is imaged in this position, in other words,

3:20

in a dorsiflex position, or whether the foot is

3:23

imaged in a plantarflex position, and whether

3:26

the patient is on their back or on their stomach.

3:29

And we'll explain why this is

3:31

important when we get into sequences.