vibration sono-elastography for intra-operative localization of breast tumor
TRANSCRIPT
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