Abstract: The invention provides a method of detecting acute renal allograft rejection in a subject as well as a method of stratifying a subject received a renal allograft and undergoing immunosuppressive therapy for alteration of the therapy. These methods comprise administering to the subject a probe capable of specifically binding to T lymphocytes, the probe being detectable by ultrasound. An allotransplanted kidney of the subject is exposed to ultrasound. The level of T lymphocytes in the kidney is detected. An elevated level of T lymphocytes in the kidney indicates an increased risk of renal allograft rejection and/or that the subject is in need of an alteration of the immunosuppressive therapy.

Abstract: A system for injecting a multi-component fluid into a patient includes a syringe and at least one agitation element moveable within the syringe to agitate the fluid. The agitation element includes surface structures to create vortices/mixing in the vicinity of the agitation element. An agitation element can also include surface structures to reduce the area of contact between the agitation element and another surface (for example, the interior wall of the syringe). An agitation element may also include a coating that includes at least one component of the multi-component fluid to be released into the fluid. A system for injecting a multi-component fluid into a patient includes a syringe and at least two agitating elements moveable within the syringe to agitate the fluid. A first one of the agitating elements has a density greater than a density of the fluid, and a second on of the agitating elements has a density less than the density of the fluid.