Evaluation of Early-phase Biodistribution in ¹²³I-ioflupane SPECT

It is reported that pharmacokinetics after intravenous injection of ¹²³I-ioflupane may reflect cerebral blood flow. In this study, the early-phase pharmacokinetics of ¹²³I-ioflupane in 10 healthy volunteers was analyzed over time using dynamic single-photon emission computed tomography (SPECT) immediately after intravenous injection. We also examined the correlation between the ¹²³I-IMP imaging and the ¹²³I-ioflupane early-phase image for 14 cases in which both dopamine transporter (DaT) imaging by ¹²³I-ioflupane and cerebral blood flow imaging by ¹²³I-IMP were performed on the same camera. The time-activity curve between cerebellum (CBL) area and each area of anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA) showed distribution characteristics similar to ¹²³I-IMP from immediately after intravenous injection until 20 minutes after administration, and there was no conspicuous washout. The regression line and the correlation coefficient of the Z-score of three-dimensional stereotactic surface projections (3DSSP) (decrease) of the early-phase imaging of ¹²³I-ioflupane and the ¹²³I-IMP imaging are y=0.7546x+0.3562, r=0.8169 (P<0.01) at 0-10 minutes of ¹²³I-ioflupane, and y=0.7412x+0.3027, r=0.8280 (P<0.01) at 0-15 minutes of ¹²³I-ioflupane, and y=0.7400x+0.2456, r=0.8449 (P<0.01) at 0-20 minutes of ¹²³I-ioflupane, showing a strong correlation at all timings. Therefore, ¹²³I-ioflupane early-phase pharmacokinetics after intravenous showed distribution characteristics similar to ¹²³I-IMP, indicating the possibility that early images may be useful in a clinical practice.