@article{oai:repo.qst.go.jp:00048590,
 author = {Naganawa , Mika and Lim, Keunpoong and B. Nabulsi, Nabeel and Shu-fei, Lin and Labaree, David and Ropchan, Jim and C. Herold, Kevan and Huang, Yiyun and Harris, Paul and Ichise, Masanori and W. Cline, Gary and E. Carson, Richard and Ichise, Masanori},
 issue = {5},
 journal = {Molecular Imaging  and Biology},
 month = {Oct},
 note = {Purpose

Previous studies demonstrated the utility of [18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ) as a positron emission tomography (PET) radiotracer for the vesicular monoamine transporter type 2 (VMAT2) to quantify beta cell mass in healthy control (HC) and type 1 diabetes mellitus (T1DM) groups. Quantification of specific binding requires measurement of non-displaceable uptake. Our goal was to identify a reference tissue (renal cortex or spleen) to quantify pancreatic non-specific binding of [18F]FP-(+)-DTBZ with the inactive enantiomer, [18F]FP-(−)-DTBZ. This was the first human study of [18F]FP-(−)-DTBZ.


Procedures

Six HCs and four T1DM patients were scanned on separate days after injection of [18F]FP-(+)-DTBZ or [18F]FP-(−)-DTBZ. Distribution volumes (VT) and standardized uptake values (SUVs) were compared between groups. Three methods for calculation of non-displaceable uptake (VND) or reference SUV were applied: (1) use of [18F]FP-(+)-DTBZ reference VT as VND, assuming VND is uniform across organs; (2) use of [18F]FP-(−)-DTBZ pancreatic VT as VND, assuming that VND is uniform between enantiomers in the pancreas; and (3) use of a scaled [18F]FP-(+)-DTBZ reference VT as VND, assuming that a ratio of non-displaceable uptake between organs is uniform between enantiomers. Group differences in VT (or SUV), binding potential (BPND), or SUV ratio (SUVR) were estimated using these three methods.


Results

[18F]FP-(−)-DTBZ VT values were different among organs, and VT(+) and VT(−) were also different in the renal cortex and spleen. Method 3 with the spleen to estimate VND (or reference SUV) gave the highest non-displaceable uptake and the largest HC vs. T1DM group differences. Significant group differences were also observed in VT (or SUV) with method 1 using spleen. SUV was affected by differences in the input function between groups and between enantiomers.


Conclusions

Non-displaceable uptake was different among organs and between enantiomers. Use of scaled spleen VT values for VND is a suitable method for quantification of VMAT2 in the pancreas.},
 pages = {835--845},
 title = {Evaluation of Pancreatic VMAT2 Binding with Active and Inactive Enantiomers of [18F]FP-DTBZ in Healthy Subjects and Patients with Type 1 Diabetes},
 volume = {20},
 year = {2018}
}