0:00

A brief word about the needles used in, uh,

0:03

mammographic guided core biopsies.

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We use vacuum assisted needles currently, um,

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decades ago we used spring loaded needles.

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Right now, I think

0:13

that most facilities would have vacuum assisted needles.

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Um, regardless of the manufacturer, the parts

0:18

of the needle are very similar.

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Um, they all have a tissue acquisition chamber

0:24

that the vacuum pulls the tissue into.

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This can be called the trough, the notch or the aperture.

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There are options for length of that aperture,

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which I'll go over a little bit later, as well as gauge

0:36

of the needle or diameter of the needle.

0:40

In short axis, you can see that the trough

0:43

or the aperture is directional.

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It's not entirely over the circumference of the needle.

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It's facing one direction.

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So for example, this yellow circle is the target.

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The trough is the straight line,

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and the white is the needle.

0:59

And then the needle can be rotated 360 degrees

1:03

to obtain different sites of sampling within that target.

1:07

In some cases, the needle is at the periphery of the target,

1:10

in which case we may only sample in a few, uh,

1:14

different locations.

1:15

For example, this arc of a circle.

1:19

Moving on to discussion of technique

1:22

of mammographic guided core biopsies.

1:24

This is a 53-year-old patient

1:27

who had a screening mammogram performed,

1:29

and there are new calcifications in her left breast.

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I'm circling them here because they are very faint

1:36

and hard to appreciate, uh, without the ability to zoom in

1:40

on a mammo workstation.

1:43

These were called by RAD zero

1:45

and need additional imaging evaluation.

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Remember that the only birads available

1:50

for screening is zero, one or two.

1:55

The patient was called back for diagnostic evaluation

1:58

and magnification views were performed showing

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grouped amorphous calcifications, which are new,

2:06

harder to see in this view.

2:09

And because of these features,

2:11

they are birads four B suspicious.

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These are not the type of finding

2:17

that we would interrogate with ultrasound.

2:20

It would not be helpful.

2:21

We would not be able to see these small particles.

2:24

There's no associated mass, so we would proceed

2:27

with biopsy using mammography.

2:30

So how do we get the biopsy needle to the target?

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So each point in space, each target can be defined

2:38

by three coordinates of X, Y, and Z.

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So the goal of mammographic targeting is getting the

2:45

needle to the biopsy.

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Site X

2:48

and Y are very easy to determine from a single 2D image.

2:53

X is parallel to the floor. Y is perpendicular to the floor.

2:58

The challenge is determining the depth or z of the target.

3:04

Again, a diagram of a patient being positioned on a prone

3:07

stereotactic core biopsy table.

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Here is the detector. Here's the paddle.

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The paddle, um, that is compressing the breast.

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It actually has a window which allows the needle

3:19

to get into the breast.

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And the x-ray tube would be beyond the field of view

3:23

of these pictures, um, but would be on the left.

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Here's a, uh, slightly magnified view of the same things.

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Detector compression paddle, here's the needle,

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and this is the target.

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So the depth or Z is the distance from a reference point,

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and the reference point can vary depending upon the

3:43

manufacturer from the surface of the breast

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or from the detector.

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So z the point

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of reference varies depending upon the manufacturer.