Apparatus and method for monitoring a prostate in a human body in which a fluid flows and which is characterized by a change in the prostate with time in space for the purpose of diagnosing a prostate condition, particularly cancer. A preselected place in the prostate is monitored to collect data at two or more time points correlated to a prostate event. The data is indicative of a prostate parameter that varies with time as a function of at least two variables related to prostate wash-in and wash-out behavior. A calibration map is made on a calculated basis with each pixel or voxel representative of a color hue indicative of wash-out behavior and a color intensity indicative of wash-in behavior. When a satisfactory map is obtained, the collected data is processed on the basis of the map to obtain an image of the preselected place with each spatial unit thereof correlated with a color hue and a color intensity. Software and a data processing system are provided to develop the calibration map. The calibration map and image of the preselected place are also novel implementations.