Non-invasive breast tumour grading using ultrasound

frequency-dependent backscatter analysis

Hadi TadayyonJune 11, 2012

Clinical challenge

◦ High risk for metastasis

Characterized as:◦ > 5 cm long axis◦ Skin/chest wall involvement◦ Lymph node involvement

Tumour grade – a histological feature that is a prognostic

indicator and is important for treatment design

◦ Determined from pathological examination of biopsy sample

◦ Higher grade higher degree of malignancy / poorer prognosis

Our goal: ultrasonically detect variation in tumour grades

Locally advanced breast cancer (LABC)

Midband fit, slope, and intercept used to differentiate:◦ Prostate cancer from benign tumours1

◦ Metastic from non-metastatic lymph nodes2

Acoustic scatterer spacing used to characterize breast lesions as benign or malignant3

Quantitative ultrasound characterization of cancers

1. Feleppa et al., 2004 IEEE Trans UFFC, 43(4), 609-619, (1996)2. Mamou et al., Ultrasound in Med. & Biol., 37(3), 345–357, (2011)3. Y. Bige et al., Ultrasonics 44 , 211–215, (2006)

Can LABC tumours be characterized in terms of

grade using quantitative ultrasound?

Given:

◦ Retrospective in-vivo clinical breast data (N=43)

◦ A diagnostic ultrasound machine

Research Question

Methods: data collection and classification

Tumour ROI

1 cm

Normal breast ROI

QUSMidband fit (MBF)

Slope (SS)Intercept (SI)

Scatterer spacing (SAS)

GI (N=3)

GII (N = 22)

GIII(N = 18)

10 MHz fc linear array transducer (Ultrasonix, Canada) 4-7 cm depth 5 MHz 50% bandwidth

Normal tissue ROI

Methods: Spectral analysis

Depth-dependent spectral normalization (reference phantom)

Variable bandwidth linear regression

Discrete depth spectral normalization (reference reflector)

Auto-regressive (AR) spectral estimation and autocorrelation-derived scatterer spacing

Results: QUS distributions among tumour grades

Mann-Whitney test: p = 0.032

Results: parametric images of scatterer spacing

GI GII GIIINT

0

0.5

SA

S (m

m)

10 um

1 cm

The link of scatterer spacing to biology

Mean spacing between glandular islands = 200 um

100 um

A potential method to non-invasively characterize tumour

grade was proposed

Scatterer spacing statistically different among tumour grades

(ANOVA test & Mann-Whitney test)

Scatterer spacing is linked to spacing between glandular

islands

Small sample size for GI

◦ In large population study – 362/1409 = 25%

◦ In our study, 3/43 = 7%

Cannot evaluate classification due to insufficient parameters

Future directions: investigate other QUS parameters

Discussion & conclusion

Acknowledgments

Czarnota Lab, University of Toronto• Dr. Czarnota• Dr. Omar Falou• Mike Papanicolau• Sara Iradji• Ervis Sofroni

Ryerson University• Dr. Lauren Wirtzfeld

University of Illinois• Dr. Michael Oelze

CGSD

Tumour grade

Increasing risk of metastasis

Grade I Grade II Grade III

Total score 3-5 6-7 8-9