Spatial Distribution of Hot Spots in Breast

TumorsPhilip Wong

Department of Medical Biophysics

University of Western Ontario

March 23, 2011

Acknowledgments Dr. Gelman

Fang Liu

Dr. MacDonald

Introduction Breast cancer is a cancer that is found in the

tissues of the breast

Most common cancer among women

Detected by the presence of a breast tumorMalignant Benign

Diagnosis Accuracy of the diagnostic method used to

differentiate between benign and malignant tumors is important

Dynamic contrast enhanced-MRI (DCE-MRI)

“Hot spots” refers to areas within the tumor where the contrast agent is rapidly taken up (3 minutes)

Motivation and Objective Provide an objective means of diagnosis

Non-fibroadenoma (NF) (benign) and malignant tumors were not easily distinguished

Compare spatial distribution of hot spots in NF and malignant tumors

Approach Developed a code in MATLAB to calculate

hot spot volumes in the outer perimeter of the tumors

Statistical analysis (Mann-Whitney test)

Hypothesis Malignant tumors will have a greater hot

spot volume in the outer perimeter than NF tumors

Methods

Tumor Mask Matrix

Methods

Tumor Mask Matrix after one erosion

Methods

Hot Spot Mask Matrix

Methods

Hot Spot Mask Matrix from eroded tumor

Methods Repeated this process for 16 NF tumors and

20 malignant tumors

Defined outer perimeter as 25% of tumor volume

Linear interpolation to find outer hot spot volume (OHS) (hot spot in outer perimeter)

Methods Expressed OHS as a fraction of total tumor

volume

Ran a Mann-Whitney test to compare the fractional OHS of NF and malignant tumors

Compared fractional OHS with fractional total hot spot volume (THS)

ResultsF

ract

iona

l Out

er H

ot S

pot

Vol

ume

n =16 n =20

p = 0.3477(p > 0.05)

Tumor Type

Results Fractional OHS and THS

Non-fibroadenoma: p = 0.0035

Malignant: p = 0.000011

Discussion No significant difference between the OHS of NF

and malignant tumors

Suggests that NF tumors behave similarly to malignant tumors in terms of their vasculature

Significant difference between OHS and THS in both NF and malignant tumors

Implies that most of hot spot volume is still located in the center of the tumor

Future Work Observe effects of different thresholds

and outer perimeters

Examine why NF are similar to malignant tumors

Run Mann-Whitney test between a non-fibroadenoma subgroup and malignant tumors

Conclusion No significant difference in spatial

distribution of hot spots between NF and malignant tumors

Significant difference between OHS and THS in both NF and malignant tumors

Questions?