A method for injection of an imaging contrast into a patient, includes: a. in a first phase, injecting a fluid having a first concentration of contrast agent for a first period of time and b. in a second phase, injecting a fluid having a second concentration of contrast agent for a second period of time. The osmolarity of the second phase is higher than the osmolarity of the first phase. The method can further include: c. in a third phase, subsequent to the second phase, injecting a fluid having a third concentration of contrast agent for a third period of time. The osmolarity of the third phase is lower than the osmolarity of the second phase. In embodiments in which the composition of the contrast agent of the third phase is the same as the composition of the contrast agent of the second phase, the third concentration can be lower than the second concentration.
