Abstract: A medical apparatus (200, 300, 400, 500) determines the concentration distribution of sonically dispersive elements (606, 2001) within a subject (306, 604, 1004), wherein the medical apparatus comprises: a memory (212) for storing machine executable instructions (224, 226, 228, 230, 232, 318) and a processor (206) for executing the machine executable instructions. Execution of the instructions cause the processor to: receive (100) shear wave data (214) descriptive of the propagation of shear waves (310, 608, 1118) within the subject for at least two frequencies; determine (102) a mechanical property (316, 618, 620) of the subject using the shear wave data at each of the at least two frequencies; determine (104) a power law relationship (218, 702) between the at least two frequencies and the mechanical property; and determine (106) the concentration distribution of the sonically dispersive elements within the subject using the power law relationship and calibration data (222, 704, 800).

Abstract: The invention provides for a medical apparatus (200, 300, 400, 500) for determining the concentration distribution of sonically dispersive elements (606, 2001) within a subject (306, 604, 1004), wherein the medical apparatus comprises: a memory (212) for storing machine executable instructions (224, 226, 228, 230, 232, 318) and a processor (206) for executing the machine executable instructions.