A system and method for monitoring a subject are presented. The system includes a sensing device including at least one magnetic source to generate a magnetic field and an array of magnetic sensors disposed within the magnetic field. The sensor array obtains a plurality of magnetic field measurements at a plurality of locations along a vessel carrying a fluid including one or more magnetic particles. Further, the system includes a processing subsystem communicatively coupled to the sensing device, where the processing subsystem determines variations in the measurements caused by magnetization-relaxation of the magnetic particles based on a coupled model that defines behavior of the fluid in the varying magnetic field based on principles of magnetization-relaxation, bulk motion of the magnetic particles towards a determined gradient of the magnetic field, magnetostatics, and conservation of momentum. The processing subsystem estimates values of one or more desired parameters based on the determined variations.提出用於監測對象的系統及方法。該系統包括感測裝置，其包括至少一個磁源以產生磁場，及設置在該磁場內的磁感測器陣列。該感測器陣列得到在沿著運載包括一或多個磁性粒子的流體之導管的複數個位置的複數個磁場量測。另外，該系統包括通訊地耦接至該感測裝置的處理次系統，其中該處理次系統基於耦合模型決定該等量測中由該等磁性粒子的磁化鬆弛所導致的變化，該耦合模型基於磁化鬆弛、該等磁性粒子朝向該磁場之已決定梯度的整體運動、靜磁學、及動量守恆的原理界定該流體在該變化磁場中的行為。該處理次系統基於該等已決定變化估算一或多個期望參數的值。
