A device for filtering emboli from blood flowing through a lumen defined by the walls of a vessel in a patient's body. The filter element is expandable from a collapsed configuration when the filter element is restrained to an expanded configuration when the filter element is unrestrained. The filter element includes a mesh including strands, each strand having a diameter. The mesh includes at least one radiopaque strand and at least one non-radiopaque strand, and wherein each strand has an index of wire stiffness EI, where EI is the mathematical product of the Young's modulus (E) and the second moment of area (I), and wherein the largest EI of a strand is no more than five times the smallest EI of a strand.