en Medical Physics and Radiation Therapy Medical Physics and Radiation Therapy Review Article Review Article Cancer stem cells (CSCs) have critical roles in tumor development, progression, and recurrence. They are responsible for current cancer treatment failure and remain questionable for the design and development of new therapeutic strategies. With this issue, medical imaging provides several clues for finding biological mechanisms and strategies to treat CSCs. This review aims to summarize current molecular imaging approaches for detecting CSCs. In addition, some promising issues for CSCs finding and explaining biological mechanisms have been addressed. Among the molecular imaging approaches, modalities including Magnetic resonance imaging (MRI) and positron emission tomography (PET) have the greatest roles and several new approaches such as optical imaging are in progress. Cancer stem cells, Molecular imaging, MRI, PET, Optical imaging 632 638 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-5603-1&slc_lang=en&sid=1 Hamed Ghaffari hamed5899@gmail.com 200319475328460064206 200319475328460064206 No Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Mohammad Reza Atashzar atashzar@sums.ac.ir 200319475328460064207 200319475328460064207 Yes Department of Immunology, School of Medicine, Fasa University of Medical Sciences, Fasa, Iran Hamid Abdollahi H_Abdollahi@kmu.ac.ir 200319475328460064208 200319475328460064208 No Department of Radiologic Sciences and Medical Physics, School of Allied Medicine, Kerman University of Medical Sciences, Kerman, Iran