Studies of magnetic carrier particles capture for blood vessel embolization

The magnetic capture of colloidal magnetic particles (MPs) flowing in capillary tubes is studied. This models magnetic embolization of "blood vessels" as a treatment for cancer. The study investigates the evolution of MPs deposition using video imaging and flow recording techniques. The parameters of practical importance (length of MPs deposits, time of capillary blocking) are estimated, and they are dependent on the initial fluid velocity, the MPs concentration and the position of capillary tubes within the magnetically active zone. The study reveals that stable deposits of colloidal MPs block - up the capillary tubes on lengths of few centimeters when the tubes are positioned in the proximity of the magnetic poles and the colloid velocity is low (< 0.5 cm/s). Depending on the particle concentration and the flow velocity, the blocking time varies between 10 to 30 minutes. A dynamic deposition regime appears when the capillary tubes are positioned far away (1.5 to 6.0 cm) from the magnetic poles. In this case the length of the MPs deposits increases up to 7.7 cm, but the deposits are unstable and avalanches take place. These results indicate that magnetic embolization is suitable for treating sub-surface cancers within the human body.