Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 8 3 2021 09 01 226 235 EN Ali Tarighatnia Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Gurkaran Johal University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, USA Ayuob Aghanejad Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran Hossein Ghadiri Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Nader Nader University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, USA 2021 05 11 2021 06 18 A variety of imaging modalities include X-ray-based Computed Tomography (CT) scan, Ultrasound (US), Magnetic Resonance Imaging (MRI), Nuclear Medical Imaging (NMI), and Optical Imaging (OI) are used to help diagnose and treat diseases through anatomical, physiological, and functional representation. With the advent of molecular imaging using nanoparticles, detailed information about properties is provided and facilitates early detection of malignancies. Now, novel approaches in nanoparticle designing, the development of hybrid imaging modalities, and improvements in the sensitivity of instruments have raised the level of disease diagnosis. Regarding the fact that the molecular imaging fundamentals and basis of materials as contrast agents are different from each other, we have updated the brief synopsis of basic principles of imaging technique containing important points in detail with a practical approach. https://fbt.tums.ac.ir/index.php/fbt/article/view/347 https://fbt.tums.ac.ir/index.php/fbt/article/download/347/214