Abstract
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Objectives By means of recently developed high resolution (transverse spatial resolutions of 3.5 mm in FWHM) and large Field-of-View (FOV, 260mm axially) clinical PET scanner, we can identify a radioactivity in internal carotid artery (ICA) during brain scanning. We tested a possibility that ICA time activity curve (TAC) can be used as an input function for quantitative CBF measurement.
Methods Six normal volunteers (3 male and 3 female; mean age, 50.2±2.7 yr) underwent H215O PET of 180 sec data acquisition. Radial artery (RA) TAC was measured by b-detector during continuous arterial blood sampling. Unilateral ICA-TAC was measured in total of 30 frames (2 sec×10 frames + 6 sec×10 frames + 10 sec×10 frames) by reading maximum count within a region of interest. Area under the ICA-TAC from initial rise to peak was correlated with that under the RA-TAC. ICA-TAC of each subject was calibrated using this correlation. Calibrated ICA-TAC based CBF were compared with the RA-TAC based CBF with a correction for tracer delay and dispersion.
Results Area under ICA-TAC (x) was significantly correlated with that under RA-TAC (y) (y=2.80x, r=0.856, p<0.05). Using this calibration factor, ICA-TAC based CBF showed highly significant correlation with RA-TAC based CBF for 24 brain regions (y=1.01x–0.54, r=0.999). The mean difference between RA-TAC based and ICA-TAC based CBF was 0.38%.
Conclusions The present study indicated that arterial blood sampling-based TAC can be substituted by ICA-based TAC by means of high resolution and large FOV PET scanner.
- © 2009 by Society of Nuclear Medicine