The methodology for developing clinical practice guidelines is evolving. The evaluation of evidence through a systematic review and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system has been implemented to provide appropriate recommendations. Detailed methodologies, including conflicts of interest (COIs) management, voting, and third-party evaluation to enhance guideline reliability, are provided by the Medical Information Distribution Service (Minds). Understanding these guideline development processes is important for physicians using the guidelines. However, no established guideline development methodology exists for diagnostic issues. By reviewing the history of diagnostic imaging guideline development in Japan, diagnosis-specific problems can be clarified. The latest “Diagnostic Imaging Guidelines 2021” covers various medical departments and presents standard imaging methods, background questions (BQs), clinical questions (CQs), and future research questions (FQs). This guideline aims to promote appropriate imaging and decision making, and its dissemination is desirable to contribute to improving patient prognosis.