STEREOTACTIC BREAST BIOPSY

Smriti Hari Associate Professor of Radiology

All India Institute of Medical Sciences New Delhi

Percutaneous Breast Biopsy

Ultrasound guided biopsy

Mammographic (Stereotactic) biopsy

MRI guided biopsy

Modality selection depends on

Visibility of the lesion

Operator preference

Principle of Stereotactic Imaging

Stereotactic imaging - Requirements

Stereo pair

Reference point

Computer

Scout image

Stereo Pair

+ 15 degrees - 15 degrees

Parallax- apparent shift of the lesion

+ 15 degrees - 15 degrees

Scout (0 degree)

Stereotactic Biopsy- Equipment

Add-on erect unit

Advantages

Cost

Space

Efficiency

Disadvantages

Access to some calcifications limited

Vasovagal episodes

Advantages

Improved access to microcalcifications in all locations

Patient comfort

Disadvantages

Cost

Space

Efficiency

Stereotactic Biopsy-Dedicated Prone Table

Stereotactic biopsy-

Careful mammographic interpretation

Planning the procedure

Informed consent

Performing the biopsy

Specimen radiography

Clip placement

Post procedural care

Assessment of histopathological concordance

Follow up imaging

Careful mammographic interpretation

Is there an indication for biopsy BIRADS 4/5 lesions

Selected BIRADS 3 lesions

Is the lesion only visible in mammography Microcalcifications

Subtle masses

Architectural distortion

Is the lesion amenable to stereotactic biopsy

Stereotactic biopsy- Limitations

Very thin breast(< 3cm compressed thickness)

Lesions close to skin

Subareolar lesions

Posterior lesions

Planning the procedure

What to target

Target on the worse looking calcifications

What approach

Shortest distance from skin to lesion

Informed consent

Performing the biopsy

Understanding the equipment

Positioning

Targetting

Needle placement errors

Acquiring samples

Hologic MultiCare Platinum and Atec Biopsy System

•360°Access

Cranio Caudal Approach

Caudo-Cranial

Approach

Lateral Approach

Reference Point

Where 3 axes (x, y, & z) intersect at right angles

0 0

50

0

+25 -25

Z axis

Positioning

Breast should be in the centre of the hole

Only one breast otherwise loss of lateral tissue

Before rotating C-arm, move breast away from the breast platform to avoid painful twisting

Positioning

Pull in lateral breast tissue

Sweep in superior breast tissue

Stabilize with both hands while bringing in the compression paddle

Positioning

There should be no gap b/w the breast and breast platform –loss of posterior tissue

Elevated inframammary fold

Positioning

Pt positioned with area of interest in the Bx window

Be alert for pt motion Mark the corners of targeted

area

Take scout image

Scout view – Straight On

Reposition if the lesion is not imaged in the center of the window

Targeted Inferior

Mulit-Pass

Targeted off the line

Targeted inferior

Scout view – Stereo Pair

Confirm reference point

Target the lesion

Transmit the target coordinates

Targeted Inferior

Stroke vs. Stroke Margin

The distance the probe moves forward starting in the cocked position to the fired position.

STROKE

The distance from the probe tip to the detector/breast platform once fired.

STROKE MARGIN

STROKE MARGIN FORMULA

T (compression thickness)

+12mm (paddle thickness)

-Stroke (biopsy device)

-Pre-fire (Z value – pull back of instrument)

= Stroke Margin

Stroke and Stroke Margin

Compression Thickness

Compression Plate Detector or Breast Platform

12 mm

Target

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Pre-Fire

Stroke and Stroke Margin

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Pre-Fire Post-Fire

Stroke Stroke Margin

Stroke and Stroke Margin

Stroke Margin should always be positive

Correcting Negative Stroke Margin

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Reposition from opposite angle

Pre-Fire

Correcting Negative Stroke Margin

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Pre-Fire Post-Fire

Correcting Negative Stroke Margin

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Don’t dial in as far for Pre-Fire

Adjusted Pre-Fire e.g., -4

Original Pre-Fire

-2

Correcting Negative Stroke Margin

Compression Thickness

Compression Plate

Detector or Breast Platform

12 mm

Target

Pre-Fire Post-Fire

SHORT CUT FORMULA FOR

STROKE MARGIN CALCULATION

Z + (variable) must be less than or equal to compression

Set up the biopsy device

Disinfect the skin

Attach the biopsy device

Move to Z position

Align needle tip to reference point

Z-zero the needle

Vacuum assisted Biopsy Device

Needle insertion

Move to target Move the needle close to

the skin Inject LA and make a skin

nick Advance the needle into

the breast using the Z dial until the Z differential has been met

Take pre-fire images Evaluate needle position

Prefire images

Pre-fire Position

-15 +15

x x

Pre-fire Pullback -2

Is the Needle in the Correct Position?

• Pre-fire & Post-fire Needle Position – Is the Needle Aligned to the Lesion?

– Is the Needle in the Correct Position?

– Has the Lesion Moved?

– How Do I Correct the Situation?

How Do We Know We Have A Needle Error ?

Select view stage cursors to

determine lesion/patient movement

Retarget if concerned about the position of the lesion

X or Horizontal Error

Sampling should be increased between 12 and 6 o’clock going through 3 o’clock

X or Horizontal Error

Sampling should be increased between 12 and 6 o’clock going through 9 o’clock

Y or Vertical Error

Sampling should be increased between 9 and 3 o’clock going through 12 o’clock

Y or Vertical Error

Sampling should be increased between 9 and 3 o’clock going through 6 o’clock

Z or Depth Error

The depth must be increased by advancing the probe

Z or Depth Error

The depth must be decreased by pulling back the probe

Fire the biopsy gun

Take post-fire images

Evaluate needle position

Post Fire

Post Exam

Post-fire Position

-15 +15

x x

Obtain multiple tissue cores

Take post-biopsy stereo images

Specimen Radiography

Confirms calcification retrieval

Caner can be missed, if calcification is not demonstrated* Miss rate 1% with retrieval

11% without retrieval

Recommended for US guided biopsies also

*Radiology 2004;233:251-54

VAB: Marker Clip Deployment

Deployed at the end of VAB If complete removal of lesion is

expected

If biopsy diagnosis is cancer, metallic clip facilitates hook wire localization

Also recommended prior to chemotherapy in LABC For any size of mass

Clip placement

Images for Documentation

Scout (straight on)

Scout (stereotactic pair)

Pre-fire (stereotactic pair)

Post-fire (stereotactic pair)

Specimen radiograph

Post clip placement

Post procedure mammogram (two view)

Post Procedure

Light compression at biopsy site (not at the puncture site) for 10 minutes

Patient to avoid strenuous ipsilateral arm movements for 24 hours (lifting, pushing)

Observe for local bleed/ breast enlargement

Complications of breast biopsy are rare Bleed, hematoma, infection Vasovagal attack

Misdiagnoses can be minimized Accuracy depends on showing representative

microcalcifications on specimen X-ray

Histology must be correlated with imaging

If biopsy results do not match expectation (imaging histology discordance) Re-biopsy

Malignancy in up to 33%*

Surgical excision, if high risk lesion on biopsy Malignancy in up to 31%#

Two years follow-up of benign biopsy results

*Breast Cancer Res Treat 2007;101:291-97

#Am J Surg 2006;192:534-37

Take Home Message

Accurate and reliable breast biopsy can be performed using stereotactic technique

All biopsy results must be correlated with imaging. If results are not concordant - follow up!

Radiologist should be responsible for initiating, performing and auditing results of image guided breast

Problem lesions

Lesions near the chest wall

Lesions near chest wall

Pt relaxed

Vigorous breast traction and firm compression

Arm through hole

Helps with lateral lesions

Remove the table pad

Helps with medial lesions

Arm through hole with special angled compression paddle

Special Positioning Techniques

Drop the shoulder in to view axillary tissue

Compression ~55 mmCompression ~55 mm

Compression ~55 mmCompression ~55 mm

Superficial lesion Pre-fire

Superficial lesion Post-fire

Thin breast – petite needle Pre-fire

Thin breast - petite needle Post -fire

Compression

~25 mm

Compression

~25 mm

Compression

~25 mm

Compression

~25 mm

Bolstering to increase compression thickness

Rolling towards breast platform while applying compression

Easing the breast to bring in posterior tissue

Release compression slightly,pull breast platform towrds th breast. It will relax the posthe breast and allow more posterior tissue to be pulled in before recompression is reapplied