Magnetic resonance imaging (MRI) for diagnostic evaluation of the breast was performed in 61 patients who visted the Breast Clinic of our hospital and were suspected to have malignant tumors by physical examination and mammography between January and December 1999. In 58 patients undergoing histological diagnostic tests (8 with benignancy and 50 with breast cancer), we compared the imaging characteristics and the time-signal intensity curves acquired by dynamic imaging between benign and malignant lesions, and evaluated the usefulness of analyzing enhancement patterns on contrast MRI. Contrast MRI revealed strong tumor enhancement in all patients; the mean time required for the signal intensity to reach a peak was about 7 min in patients with benign tumors and about 2 min in those with breast cancer. Peripheral ring enhancement was observed in 40 of the 50 patients with breast cancer (80.0%), while such enhancement was not noted in any of the patients with benign tumors.
Although diagnosis of breast disease by imaging has primarily relied on mammography and ultrasonography, the pattern of contrast enhancement on dynamic MRI also appears to be useful for determining the treatment method of breast tumors.

Monitoring of the safety profile for the approved medical products consists of routine pharmacovigilance activities for all drugs and additional pharmacovigilance activities for product-specific concerns. Signal management is an important part of routine pharmacovigilance activities, so EMA and FDA have published the guidelines for signal management in various documents. The AMED Risk Management Plan （RMP） research group, which started its activities in 2018 to enhance risk management plan in Japan, reviewed the guidelines and related articles and then put together the principles of signal management. The guidelines in EU and US describes the signal detection and evaluation methods including points to consider when conducting them, responsibilities of each action, and the procedures that the regulatory authorities disclose the outcome of their activities, in addition to the principles and procedures of signal management. Through the guidelines, they establish transparency for public including pharmaceutical industry. Our group first created the Japanese definitions of signal-related terms. Based on them, we created high-level concept for a series of activities from signal detection to risk identification and discussed the future vision of signal management in Japan.