The specific uptake size index for quantifying radiopharmaceutical uptake

Abstract

Quantitative indices of radionuclide uptake in an object of interest provide a useful adjunct to qualitative interpretation in the diagnostic application of radionuclide imaging. This note describes a new measure of total uptake of an organ, the specific uptake size index (SUSI). It can either be related in absolute terms to the total activity injected or to the specific activity in a reference region. As it depends on the total activity in the object, the value obtained will not depend on the resolution of the imaging process, as is the case with some other similar quantitative indices. This has been demonstrated in an experiment using simulated images. The application of the index to quantification of dopamine receptor SPECT imaging and parathyroid-thyroid subtraction planar scintigraphy is described. The index is considered to be of potential value in reducing variation in quantitative assessment of uptake in objects with applications in all areas of radionuclide imaging.

Reduction in camera-specific variability in [123I]FP-CIT SPECT outcome measures by image reconstruction optimized for multisite settings: impact on age-dependence of the specific binding ratio in the ENC-DAT database of healthy controls

“…The SBR was computed according to the Southampton method developed by Fleming et al to reduce the impact of recovery and partial volume effects [31]. More precisely, the SBR was computed according to the formulas:…”

“…The striatal ROIs were about the same size as described in the original paper ( Fig. 1 of Fleming et al [31]). The mean concentration of FP-CIT in the whole brain, without the striata, or in the occipital lobe or in the cerebellum was used as reference C R .…”

Visualizing pancreatic β-cell mass with [11C]DTBZ

“…ROI were manually placed across image planes for the determination of time-activity curves. The ROI in STZ-induced diabetic rats was drawn using known landmarks, any remaining The comparison of [ 11 C]DTBZ uptake among the pancreata of all animals studied was performed by calculating the specific binding index (SBI), which relates uptake concentration in the object of interest C p (i.e., pancreas) to a reference region C r (e.g., kidney), as discussed by Fleming et al [36]. Unlike standardized uptake volume, the SBI requires that nonspecific contribution be subtracted from the total uptake.…”

Partial Volume Correction Strategies in PET

“…Fleming and colleagues [21] have proposed another simple method to account for the PVE by measuring the total uptake rather than the activity concentration in the ROI using a new index, the specific uptake size index. The technique consists in defining volumes of interest for the structure of interest (eg, striatum), large enough to guarantee the inclusion of all the partial volume counts detected outside the physical volume of the structures.…”