Advances in Microwave, Millimeter Wave, and Terahertz Imaging for Breast Cancer Detection: A Comprehensive Review of Antenna Designs, Challenges, and Imaging Techniques

Breast cancer remains one of the most deadly and prevalent malignancies in women globally. Conventional imaging technologies like X-ray mammography, ultrasound, and magnetic resonance imaging (MRI) have proven useful but face limitations such as high cost, ionizing radiation, or poor spatial resolution. Microwave Imaging (MI) has gained attention due to its non-invasive nature, safety, comfort, speed, and affordability. However, most MI systems operate below 10 GHz, resulting in limited resolution and reduced image quality. To address this, higher-frequency bands such as millimeter-wave (mmWave) and terahertz (THz) are being explored for their ability to detect smaller tumors and provide enhanced resolution. This review presents a comprehensive survey of microwave, mmWave, and THz imaging technologies for breast cancer detection. It highlights recent advancements in antenna designs tailored for each modality, including performance metrics such as size, gain, and bandwidth. Challenges in antenna miniaturization, gain enhancement, and substrate choice are discussed alongside practical solutions. The paper offers a comparative evaluation of imaging modalities to emphasize their complementary roles in resolution, depth, and clinical integration. An electrochemical perspective is also included to explain dielectric contrasts in tissues. Finally, recent trends in image reconstruction techniques are examined for improved tumor localization.