Vibration Sono-Elastography for

Intra-operative Localization of Breast Tumor

Tasnuva Fauk

Md Kafiul Islam

The Need (From Dr Anthony)

An accurate method to localize an impalpable lesion which gives real time feedback and allows the surgeon to continue operating with both hands.

A way to accurately determine tumor margins intraoperatively within 10 minutes.

Motivation

Surgical Guidance; not Diagnosis

Cost

OT Compatibility

Ease to use

Radiation

Background of Elastography One of the key medical methods

for detection and characterization of pathologies is the assessment of tissue stiffness by palpation.

Palpation is performed by applying external forces on the body surface that induces tissue displacements from which elastic constants can be subjectively estimated.

Elastography is a promising method to assess tissue differences in stiffness or elasticity what was historically assessed manually by palpation. Concept of Elastograpgy: Layers in Jelly-

like material show difference in stiffness after light compression

What is Elastography

Non-invasive medical imaging technique that detects tumors based on their stiffness (elasticity) compared to normal tissue

Elasticity is related to the density of blood vessels.

Tumors have more blood vessels than healthy tissue. Malignant tumors usually have even more blood vessels and a greater blood flow than benign tumors.

A tumor is normally 5-28 times stiffer than the background of normal soft tissue.

Elastic/Young’s Modulus of Breast Tissue

Measure of the stiffness of an elastic materialE = Young's modulus (modulus of elasticity)F = Force exerted on an object under tension;A0 = Original cross-sectional area through which the

force is applied;ΔL = Amount by which the length of the object changes;L0 = Original length of the object.

General Steps of Elastography

(1) Perturb the tissue using a quasi-static, harmonic or transient

mechanical source

(2) Measure the internal tissue displacements using a suitable

ultrasound, magnetic resonance or optical displacement

estimation method

(3) Infer the mechanical properties from the measured

mechanical response, using either a simplified or continuum

mechanical model

Different Elastography Techniques

Vibration Elastography

Measures tissue stiffness using low-frequency ~10–1000 Hz shear waves to vibrate a region of interest.

No clear/universal classification of Elastography!Research done for diagnosis purpose (so far), not surgical guidance

Why Elastography?Elastography can enhance sonographic images where

sonography alone has following limitations:

Can’t distinguish isoechoic lesions properly Can't image areas deep inside the breast May have trouble distinguishing from other pathologies Cannot show micro-calcifications In some cases fails to differentiate between benign and malignant

lesions Cannot detect cellular level carcinomas

Ultrasound B-mode image Corresponding elastography image

Vibration SonoElastography Vs Other Elastography

Cheaper Faster Can be made portable

Proposed Setup-1

Challenge Integrating vibrator and recorder in the same probe Real-time Image reconstruction

Proposed Setup-2 Recent concept of portable ultrasound

imaging

Improvement by addition of Elastography

The Smartphone Ultrasound Windows tablet-basedFDA-cleared ultrasound system

THANK YOU