Intracranial aneurysm treatment with flow diverters (FD) is a new minimally invasive approach, recently approved for use
in human patients. Attempts to correlate the flow reduction observed in angiograms with a parameter related to the FD
structure have not been totally successful. To find the proper parameter, we investigated four porous-media flow models.
The models describing the relation between the pressure drop and flow velocity that are investigated include the capillary
theory linear model (CTLM), the drag force linear model (DFLM), the simple quadratic model (SQM) and the modified
quadratic model (MQM). Proportionality parameters are referred to as permeability for the linear models and resistance for
the quadratic ones. A two stage experiment was performed. First, we verified flow model validity by placing six different
stainless-steel meshes, resembling FD structures, in known flow conditions. The best flow model was used for the second
stage, where six different FD's were inserted in aneurysm phantoms and flow modification was estimated using
angiographically derived time density curves (TDC). Finally, TDC peak variation was compared with the FD parameter.
Model validity experiments indicated errors of: 70% for the linear models, 26% for the SQM and 7% for the MQM. The
resistance calculated according to the MQM model correlated well with the contrast flow reduction. Results indicate that
resistance calculated according to MQM is appropriate to characterize the FD and could explain the flow modification
observed in angiograms.