EVALUATION OF ULTRAFILTRATION FOR THE FREE-FRACTION DETERMINATION OF SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY (SPECT) RADIOTRACERS - BETA-CIT, IBF, AND IOMAZENIL

An ultrafiltration system was evaluated for the free-fraction measurement of SPECT radiotracers (beta-CIT, IBF, and iomazenil) used in functional brain imaging. The effect of temperature, storage, centrifugal force, tracer concentration, and percentage filtered demonstrated a relative error of <9%. As a result of the minimal temperature effect, 25 degrees C was employed for ail measurements. A comparison of the ultrafiltration system with equilibrium dialysis revealed <5% difference for beta-CIT and iomazenil, but 16% for IBF. Additionally, the time and ease of operation considerably favored the ultrafiltration system. The precision quantitated by repetition was <6 % for between-run and within-run variability. In conclusion, ultrafiltration provided rapid results, demonstrated minor analytical errors, revealed generally good correlation with equilibrium dialysis, and allowed excellent precision.