Newer Imaging Techniques for Detecting Breast Cancer

Introduction:

Breast cancer is one of the leading diagnosed cancers in women. Within the years, the chance of developing breast cancer has reached one in nine women from one in thirteen women. Each year in the United States, about 265,000 breast cancer cases are reported in women, and around 42,000 women die because of this condition. African-American women have a higher rate of death than white women. Therefore, to analyze this condition, multiple diagnostic methods have been introduced, and research is still going on to form new ways of detecting this condition as soon as possible to decrease the female mortality rate due to cancer.

The earlier detection of breast cancer with the help of artificial intelligence (AI) tools can assist in providing proper treatment to the affected person as early as possible. The same can be done with the help of ultrasound, mammography, and magnetic resonance imaging (MRI) from screening images for the precise description of the tumor. However, early detection methods are expensive and can be a painful procedure for a patient to perform.

What Are the Types of Breast Cancer?

The most common type of breast cancer include -

• Invasive Ductal Carcinoma - This is a type of cancer that usually begins in the ducts and then may progress outside the ducts or to the other parts of the breast tissue. These cancer cells can also spread or metastasize to other body parts.

• Invasive Lobular Carcinoma - These cancer cells start from the lobules and then can spread to the other nearby breast tissues. These cancer cells can also advance to other parts of the body.

What Is a Breast Imaging Reporting Data System?

Breast imaging reporting and data systems (BI-RADS) were first proposed in 1993 by the American College of Radiology, which served as a guide to standardize breast imaging reports. This was first used in mammogram reporting and is divided into seven categories -

• Incomplete (0) - No significant abnormality found; additional imaging modalities required.

• Negative (1) - No significant abnormalities, such as no masses, calcification, or asymmetry, are found.

• Benign (2) - No malignant (cancerous) lesion is found.

• Probably Benign (3) - Requires further investigation.

• Suspicious Abnormality (4) - Requires further investigation and ranges from low to moderate.

• Highly Suggestive of Malignancy (5) - Requires further investigation (more than 95 percent malignant).

• Known Biopsy-proven Malignancy (6) - Requires further investigation (breast malignancy already proven).

What Is the Need for New Imaging Methods?

The traditional methods used for detecting breast cancer may have some of the following disadvantages -

• The ability to read mammograms varies greatly among radiologists.

• Mammography has a low specificity. The possibility of founding a lesion by mammography is as low as 20 to 35 percent.

• The tissue density is the same as that of tumors and may cause difficulty in detecting them. The sensitivity also decreased in the case of dense breasts.

• X-ray radiation can also cause damage to body DNA (deoxyribonucleic acid) cells.

What Are the Different Breast Screening Modalities?

The diagnosis of breast cancer is an interdisciplinary approach that includes self-examination, doctor physical examination, breast screening modalities, and some other tests. Each of these modalities has notable benefits along with some disadvantages.

I. Pre-Screening Examinations -

Clinical-breast examination (CBE) and self-breast examination (SBE) are tests done prior to the imaging modalities. The SBE test involves self-examination by checking for changes in the physical appearance of the breast or the presence of lumps, swelling, or distortion that may lead to cysts or tumors. The CBE examination is a regular examination done by a healthcare professional. These tests have low sensitivity as compared to other modalities, but they are easy techniques to perform.

II. Traditional Imaging Tests -

1. Mammography - This test is considered the gold standard test for detecting breast cancer. In this test, high-energy X-ray photons are used in limited dosages that interact with tissue and get dissipated, and the changes found during this process are captured and imaged by using reconstruction algorithms. This test has a sensitivity of 68.6 to 83.3 percent and a specificity of 90 to 95 percent for breast cancer.

Advantages -

• Has high specificity and sensitivity in detecting cancer.

• Portable device.

• Produce good-resolution images.

• More accuracy in dense breasts when using digital mammography.

Disadvantages -

• False-positive prediction cases are high.

• Poor contrast compared to CT (computed tomography) and MRI (magnetic resonance imaging).

• Uses ionizing radiation.

2. PET/CT Imaging (Positron Emission Tomography/Computed Tomography) - In this process, high-energy radioactive isotopes are used to create two gamma particles that travel in opposite directions and reach towards the detectors. The X-ray beam interacts with the tissues, and three-dimensional reconstruction of the image is also possible. This technique has 96 percent sensitivity and 77 percent specificity for breast cancer.

Advantages -

• Image registration and fusion are accurate.

• Good contrast images.

• High sensitivity.

Disadvantages -

• Uses Ionizing radiation and radioisotopes.

• Poor resolution.

• Non-portable and expensive devices.

3. Ultrasound - A screening test that uses sound waves to create pictures of the internal organs of the body or breast tissues. This test has a sensitivity of 36 percent that can be decreased up to recent, which can be increased up to 95 percent in Doppler ultrasound, and a specificity of 86 percent that can be decreased up to 79 percent with Doppler ultrasound.

Advantages -

• High diagnostic utility among women with dense breasts.

• Portable device.

Disadvantages -

• High false-positive rates.

• Poor contrast.

4. MRI (Magnetic Resonance Imaging) - In this technique, instead of X-rays, strong magnetic fields and radio waves are used to generate images of the organs in the body. This test has 88 percent of sensitivity and 67 percent of specificity for breast cancer.

Advantages -

• Nearly Maximum sensitivity.

• Can detect the intra-ductal spread of cancer.

• Produce good contrast and high-resolution images.

• Nonionizing radiation.

Disadvantages -

• Specificity values are less, and variables require compatible equipment.

• Biopsies are difficult.

• Only the lateral side of the breast can be imaged.

• Not portable.

• Expensive device.

New Emerging Diagnostic Modalities for Breast Cancer -

1. Thermography - It is a non-invasive, radiation-free imaging tool that uses an infrared camera to produce thermogram images of heat and blood flow patterns on the surface of the body and helps in the early detection and risk assessment of breast cancer. This test has 80.5 percent of sensitivity and 73.3 percent of specificity for breast cancer.

Advantages -

• Early detection.

• Non-invasive.

• Non-radioactive.

• Best imaging modality for dense breasts.

Disadvantages -

• Easily affected by room temperature.

• High false positives and false negatives.

• Low specificity.

2. Electrical Impedance Tomography - A unique diagnostic technique in which the tissues are reproduced by reactive components rather than conductive ones and reproduces the images of the body part based on the electrical conductivity of the tissue. This test has 72 to 38 percent of sensitivity and 67 to 95 percent of specificity for breast cancer.

Advantages -

• Non-invasive.

• Non-radioactive.

Disadvantages -

• Relatively inexpensive.

• Poor resolution.

3. Microwave Imaging - This method uses microwave or millimeter waves to produce the image.

Advantages -

• Non-invasive.

• Non-radioactive.

Disadvantages -

• Low contrast in fibro glandular tissues.

• Poor resolution at higher depth.

4. Optical Imaging - In this technique, optical fibers (650-900nm) are used that produce infrared light to produce the images.

Advantages -

• Non-invasive.

• Non-radioactive.

• Inexpensive and portable.

• Good contrast images.

Disadvantages -

• High scattering of waves may decrease contrast.

• Limited imaging depth.

• Poor resolution at higher depth.

Conclusion:

There are multiple diagnostic modalities available for detecting breast cancer. However, mammography is still considered the gold standard for detecting breast cancer but is still criticized for its effectiveness. Newer imaging methods, such as high-resolution ultrasound imaging, MRI imaging, and digital mammography, along with computer analysis, have promising advantages in the future. Therefore, multiple ways can be used for early detection, which necessitates treatment effectiveness. Thus, there is a need for an imaging modality tool that is free from radiation risk, pain and anxiety, false alarm, and non-invasive.