DIET – An emerging non-invasive, portable and low-

cost approach to breast cancer screening

Prof J. Geoffrey Chase

Univ of Canterbury

Dept of Mechanical Engineering, Centre for Bio-Engineering

Christchurch, New Zealand

Overview

1. Background

2. DIET Technology

3. Clinical results

4. Summary

The Problem

Breast cancer was the most common cause of female cancer death in 1999

Over the period 1972 to 1997, the annual number of breast cancer deaths increased from 427 to 643[1]

Breast cancer is over represented among Maori (in NZ) and other ethnic groups worldwide

[1] NZ Ministry of Health, 2002

Breast Cancer Screening Reduces Mortality (Tabar et al, 2003)

• No real difference• Results due to improving care

• Screening = More early detection

+20%

Why? Low Compliance & Access

Source: NZ Ministry of Health, Trends and Projections 2002.

What you don’t see can kill you! [Breast Screen Aotearoa]

Goal is 70% every 2 years, but we get ~60% -- 40% missing!

• Predominant compliance rates in the US and EU range from 50-80% based on many factors

• Eligible populations (over 50 years) are growing demographically for next 10-20 years

• Certain sub-groups have very low screening rates and thus much higher mortality• Occurrence rates don’t seem to particularly favor any group

Screening

Screening has resulted is fewer deaths and earlier treatment

Concerns of screening Patient dose

When should women start screening

Costs

Resources

Impacts of false positives (in a gold-standard test that can only be done infrequently at older ages)

However, fundamentally, mammography is a scarce and increasingly costly resource … One thus cannot simply go get a repeat test to confirm, especially if you are

younger

Current Diagnostic Techniques

Palpation/Clinical Breast Examination (CBE) Very subjective Primary form of diagnosis Most mammograms occur after being

found this way first

Mammography only modality recommended for screening X-rays, breast compression (painful) Lower compliance due to pain, cost and access

Ultrasound High level of operator skills Significant (sensor) noise

MRI Very accurate, but expensive Very few can be served

No screening programs in most developing nations! Cost and X-Ray dose are major factors

Mammography

MRI

Problems with Existing Techniques

Currently, predominant breast cancer screening methods are:

Uncomfortable

Subject the patient to doses of radiation

Require expensive, location specific equipment and clinical staff.

They thus have relatively limited throughput (not enough capacity)

They are also low contrast as cancerous tissue density varies only ~5-10% from healthy tissue

Coupled with resulting low compliance rates the average tumour size detected is ~1cm = 10x larger than possible

What’s Needed?

An all new approach Must be clinically and commercially feasible Must address compliance (w/ screening) issues Must offer high throughput in terms of speed to test and access

An ideal design list would include: Low cost equipment with no need for specialist technician Portable No X-Ray dose Equal efficacy (1cm detection) compared to mammography Greater comfort (no compression)

Succinctly: less invasive, low cost screening system with more objective diagnosis (less ‘human error’)

The DIET Concept

DIET = Digital Imaging-based Elasto-Tomography

Can we meet all these needs?

Governors Bay, Christchurch Sunset over Southern Alps, Christchurch

The DIET System Concept

Advantages of the DIET Concept

Screening from a younger age (no radiation dose)

Possible to build a history (every year!)

Less painful alternative (equals higher compliance)

Accuracy (initial target 1cm)

Portability and ease of use (no specialised technician and no loss of compliance due to travel)

Scalability (will improve as silicon technology used improves)

Should be low cost (low-cost technologies used)

Prototype Development

Laboratory Hardware

1st Clinical prototype

DIET device at Canterbury BC

So, does it work??

If we could measure surface motions could we detect cancerous lesions, from surface data only?

Lake Mathieson, Mirror LakesWest Coast of S. Island

Lindis Pass and into WanakaCental Otago, S. Island

So, how does it work? And does it?

3 main steps: Vibration and image capture

Surface motion: (a) tracking and (b) characterisation

Diagnose based on surface motion

Proof of concept clinical trials as part of ergonomic and comfort trials shown Multiple volunteers, multiple frequencies of actuation

Test of technology and proof of clinical concept

Step 1: Vibration & Image Capture

Vibrate breast from underneath and capture digital image sequences from 5 cameras

Silicone gel with fiducial markers Simulation of human breast

Step 2a: Surface Motion Tracking

Markers tracked in 2D, then 3D correspondences

Optical flow skin tracking (better resolution)

Camera 1 Camera 2 Full 3D reconstruction

Fiducial tracking Skin tracking

Step 2b: Motion characterisation

Motion data is parameterised to allow diagnostic processing

Elliptical path characterises motion in 3D (at each frequency)

Motion flows around a hard tumor like water around a rock changing amplitude and phase asymmetrically

Z-amplitude

Z-phase

Step 3: Diagnosis from tumour effect on motion

Silicone phantom with 20mm tumour at 6 o’clock Motion images alone can potentially give yes/no answer about

tumour inclusion Readily automated ... Entirely objective

Re Amplitude z-phase

In vivo results (preliminary)

Breast from ongoing trial

30mm tumour between 1-2 o’clock, left outer upper quadrant

Same effects as in phantoms are observed

TOP

BOTTOM

LEFTRIGHT

Z-phaseRez-amplitude

Some more visual outcomes

Both breasts of each subject shown at one frequency

120mm not shown, as it is almost entire breast

30mm @ 1:30 o’clock 20 + 8mm @ 2:30 o’clock

11mm @ 10:30 o’clock

DIET human trial summary

Ergonomics/Calibration trial

18 Subjects, age 49.3 (SD 8.5)

36 breasts imaged (both on each subject)

4 breasts with malignant tumors (11, 30, 20+8, 120mm)

2 breasts with benign cysts (clusters of 10-21mm, )

30 healthy breasts

Range of sizes and shapes see below.

First Uses: A 3 word case

Under-age

Under-served

Under-equipped

Plenty of “room” for a new modality like this

A Brief Summary

DIET is an all new approach to breast cancer screening that offers several potential advantages over current methods

Initial simulation and experimental proof of concept studies showed that it might be possible to achieve realistic screening (~1cm inclusion size detection)

The main imaging and reconstruction steps are technologically challenging

Initial proof of concept experiments on silicone phantoms have been successful in identifying inclusions both via reconstruction and from disturbances in surface motion

Acknowledgements

Prof Geoff Chase Dr Geoff Shaw Dr Thomas Desaive

Christina Starfinger

Dr. Chris Hann

Richard Brown

Rodney Elliot Crispen Berg

Dr. Richard Wien & Dr. Larry Ray

DIET Project Team 2004

Jerome Rouze Arnaud Milsant Ashton Peters

DIET Project Team 2005

Wili Berger

Ben Petit

Michael Wiertlewski Fabrice Jandet Edouard Ravni Anthony Hii Stefan Wortmann

Shig Kinoshita

Questions?