Background on: Breast Cancer, X-Ray and MRI Mammography

Ernesto Coto - Institute of Computer Graphics and Algorithms

Background on: Breast Cancer, X-Ray and MRI Mammography

Ernesto CotoVienna University of TechnologyInstitute of Computer Graphics and AlgorithmsComputer Graphics Group


Introduction

First stage of a research about the State of the Art on Mammography for Breast Cancer Detection

Focuses on the background knowledge about Breast Cancer, X-Ray and MRI Mammography


Background: Breast Cancer

Cancer is a general term that is used to describe a group of more than 100 diseases that cause cells in the body to divide and reproduce abnormally without control

These cells may join together to form a mass of extra tissue known as a tumor. Tumors can be malignant or benign

Malignant tumors can break away from tumors and travel, or metastasize

Breast cancer refers to a malignant tumor that has developed from breast cells



The female breast has two main components: glandular tissue and connective tissue

There are two general categories

of breast cancer

Non-invasive (or in situ) cancer confined to lobules or ducts

Invasive cancer spread to fatty connective tissue



When breast cancer is detected before it has spread to lymph nodes or to other parts of the body, the 5-year survival rate is 97%

Early detection and early treatment can improve the chances of surviving breast cancer. Currently, mammography is the best tool available to detect the earliest warning signs of breast cancer


Background: X-Ray Mammography

A mammogram is an x-ray examination of the breasts, used to detect and diagnose breast diseases

Screening mammography is used as a preventive measure for women who have no symptoms of breast disease

Diagnostic mammography involves additional x-rays of the breast to provide different views of the suspicious area, if an abnormality is detected during screening mammography, or in women with breast complaints

The x-rays can be taken at different angles tailored to the specific area of abnormality. In addition, magnification views or spot compression can be used to make the area easier to evaluate



Mammography procedure Special x-ray machines developed exclusively for breast

imaging are used to produce mammography films. These machines use very low doses of radiation and produce high-quality x-rays



Mammography procedure1. The patient wears an open wrap and undress above the

waist



Mammography procedure2. Compressing the breast is necessary to obtain the best

image



Mammography procedure3. When the breast is positioned and compression is

complete, the technologist will leave the room or step behind a screen and turn on the x-ray source



Mammography procedure4. Magnification views or spot compression

could be performed too



Results Calcifications are tiny calcium deposits within the breast

tissue. Calcifications are classified as microcalcifications (< 1/50 inchs) or macrocalcifications (larger)

Masses Can be solid or liquid (Cyst)



Staging Staging is the process used to determine the extent a cancer has

spread beyond the primary site The system used to describe staging is the Staging System of the

American Joint Committee on Cancer (or TNM system), it evaluates three components to determine the stage of a cancer:

T = The extent of the tumor, expressed in a numerical value from 0 to 4. Higher T numbers indicates a larger tumor or more extensive spread

N = the extent to which the cancer has spread to lymph nodes near the breast and the degree to which the affected nodes are fixed to other structures under the arm. It is expressed in a numerical value from 0 to 3, with the higher number denoting more extensive spread

M = the extent to which the cancer has metastasized to distant organs or to lymph nodes that are not next to the breast. It is shown in a numerical value from 0 to 1, with 1 indicating the most extensive spread



Mammography cannot determine whether an abnormal area is cancer, but it can provide guidance for further screening or diagnostic tests.

Results of mammograms are reported using a standardized system called the Breast Imaging Reporting and Data System (BIRADS)

Results range from “Assessment incomplete” to “Highly Suggestive of Malignancy”



Despite Mammography is acknowledged to be the most effective method of screening for breast cancer, the interpretation of screening mammograms is challenging

The combination of viewing a large number of cases, radiologist fatigue and the complex image structure of the breast on a mammogram can result in false negative mammogram readings

Several retrospective studies have shown that 20% to 40% of breast cancer goes undetected at the screening stage

In addition, finding cancer does not always mean saving lives



Less common diagnostic proceduresMagnetic Resonance Imaging (MRI)Digital Mammography Positron Emission Tomography Ultrasound


Background: MRI Mammography

Magnetic Resonance Imaging (MRI) can be used to obtain three dimensional images of the inner parts of the human body, without using X-rays

MRI breast imaging is a supplemental tool, in addition to mammography, to help diagnose breast cancer

MRI advantages over X-ray or CAT No radiation The ability to generate arbitrary three-dimensional views of an

object of interest The possibility to generate images of “soft“ body structures



MRI Mammography Procedure The main component of most MRI systems is a large tube-shaped or

cylindrical magnet The patient has to wears a wrap and give away any metal object



MRI Mammography Procedure To begin the MRI exam, the patient is positioned on a special table

inside the MRI system opening. A breast coil is used.



Contrast Enhanced MRI The method is based on the fact that a carcinoma is usually well

vascularized due to its strong growth. Thus a contrast medium will quickly accumulate in the tumor

The evaluation essentially consists of finding suspicious regions in the images, calculating the absorption of contrast-medium in those regions, and deriving the diagnosis from that data

Without contrast

With contrast



Benefits of Breast MRI

Can image breast implants and ruptures Highly sensitive to small abnormalities Used effectively in dense breasts Can evaluate inverted nipples for evidence of cancer Can evaluate the extent of breast cancer Can help determine what type of surgery is indicated (lumpectomy or

mastectomy) May detect breast cancer recurrences and residual tumors after

lumpectomy Can locate primary tumor in women whose cancer has spread to

axillary (armpit) lymph nodes Can spot or characterize small abnormalities missed by

mammography May be useful in screening women at high risk for breast cancer,

according to recent studies



Limitations of Breast MRI

MRI takes 30-60 minutes compared to 10-20 minutes for screening mammography

The cost of MRI is several times the cost of mammography MRI requires the use of a contrast agent MRI patients must tolerate any claustrophobia MRI can be non-specific; often cannot distinguish between

cancerous and non-cancerous tumors Minimally invasive breast biopsy techniques need to be further

developed to evaluate abnormalities detected with MRI Advanced MRI techniques are often not available at most centers

(currently available at research centers)


Further work

CAD Systems and Techniques for Mammography

RegistrationSegmentationVisualization

Documents

Background on: Breast Cancer, X-Ray and MRI Mammography