A new paper entitled “Test-Retest Variability of Relative Tracer Delivery Rate as Measured by [11C]PiB” has recently been published in the journal Molecular Imaging and Biology. The purpose of the present retrospective analysis of a previously reported test-retest (TRT) [¹¹C]PiB study was to assess the precision of [¹¹C]PiB R_1. This work received funding from the EMIF and AMYPAD projects. 

Abstract:

Purpose: Moderate-to-high correlations have been reported between the [¹¹C]PiB PET-derived relative tracer delivery rate R₁ and relative CBF as measured using [¹⁵O]H₂O PET, supporting its use as a proxy of relative CBF. As longitudinal PET studies become more common for measuring treatment efficacy or disease progression, it is important to know the intrinsic variability of R₁. The purpose of the present study was to determine this through a retrospective data analysis.

Procedures: Test-retest data belonging to twelve participants, who underwent two 90 min [¹¹C]PiB PET scans, were retrospectively included. The voxel-based implementation of the two-step simplified reference tissue model with cerebellar grey matter as reference tissue was used to compute R₁ images. Next, test-retest variability was calculated, and test and retest R₁ measures were compared using linear mixed effect models and a Bland-Altman analysis.

Results: Test-retest variability was low across regions (max. 5.8 %), and test and retest measures showed high, significant correlations (R²=0.92, slope=0.98) and a negligible bias (0.69±3.07 %).

Conclusions: In conclusion, the high precision of [¹¹C]PiB R₁ suggests suitable applicability for cross-sectional and longitudinal studies.

Congratulations to all authors: Fiona Heeman; Janine Hendriks; Isadora Lopes Alves; Nelleke Tolboom; Bart N. M. van Berckel; Maqsood Yaqub; Adriaan A. Lammertsma.

You can read the paper here.