Storch et al.: Effects of dopamine treatment on dopamine turnover

Appendix e-1

Effects of dopaminergic treatment on striatal dopamine turnover in de-novo Parkinson disease

A randomized, controlled parallel-group clinical trial

Alexander Storch, MD, Martin Wolz, MD, Bettina Beuthien-Baumann, MD, Matthias Löhle, MD, Birgit Herting, MD, Uta Schwanebeck, Liane Oehme, PhD, Jörg van den Hoff, PhD, Maria Perick, Xina Grählert, MD, Jörg Kotzerke, MD, Heinz Reichmann, MD, PhD

Supplemental Methods

Primary efficacy variable

The pre-specified primary efficacy variable was the change of the side-to-side averaged putaminal EDVR for dopamine comparing baseline and end of maintenance period (after 3 months of treatment). Primary outcome assessments were made by investigators of the Dept. of Nuclear Medicine, who were blinded to the treatment assignment and PET scan number. To determine the changes in putaminal EDVR, patients underwent three-dimensional 18F-dopa PET at baseline visit (one day before start of study treatment) and at the end of the treatment period (end of month 3; study medication was paused on the day of PET scan). PET measurements were performed on an ECAT EXACT HR+ (Siemens/CTI, Knoxville, USA) using an acquisition protocol lasting four hours as published previously e1 according to the protocol developed by Sossi and colleagues e2. All scans were started at 11.00 am with prior carbidopa administration according to Hoffmann et al. e3. An activity of 185 MBq 18F-dopa from in-house production was administered intravenously e4, e5. Emission measurements in 3D mode comprised 3 phases (90 minutes starting at injection time and 2×40 minutes beginning 120 and 190 min p.i.) following 10 minutes of transmission measurement using 68Ge rods for attenuation correction. Data were recorded in listmode using an in-house developed extension for the HR+ e6 and sorted in frames (phase 1: 6×20 s, 3×60 s, 2×150 s, 16×300 s, phase 2 and 3 in 4×10 min). Frames were reconstructed iteratively (128×128, zoom 2.5, OSEM 6 iterations, 16 subsets, Hann filter 4 mm). The three separate PET scans were merged afterwards. We used a head movement tracking system (ARTtrack from A.R.T., Weilheim, Germany) continuously during the whole PET scanning as described previously e7 to correct the frames within each phase and to correlate the later phases to the first one before merging them. Arterial blood samples were not collected.

Time activity curves were determined from three-dimensional spherical regions (volume of interest, VOI) with the software package ROVER (ABX, Radeberg, Germany). The reference region in the occipital cortex had a size of 5 ml, the four VOIs of 0.3 ml each were positioned on both sides in the caudate nucleus and the putamen, allowing averaging of the original data before the calculation. For each scan, EDVRs from the left and the right side were averaged. The activity curve of the occipital cortex served as input function for the calculation of the tissue (occipital cortex) input uptake rate constant Kocc and EDVR according to Sossi and colleagues e8, e9. The slope of the regression line after data transformation according to the Patlak plot e10 represents the parameter Kocc. It is herein assumed that the regions do not differ in the reversible transport of 18F-dopa between blood and tissue. However, tissue trapping of dopamine is not completely irreversible and its metabolites are cleared from brain to plasma with the rate kloss indicated by an increasing deviation of the data points in the Patlak plot from the straight line over time. An extended graphical analysis of the Patlak plot proposed by Sossi and colleagues e8 enables the determination of the ratio Kocc/kloss. The relationship is linear for times later than 60 min p.i. and the slope of the regression line specifies Kocc/kloss, which is the EDVR. Calculation was performed with an in-house software program. The second PET scan in each patient was co-registered to the first one.

Supplemental Results

Correlations between PET and clinical endpoints

We performed ancillary statistical analyses to assess potential associations of clinical co-variables with PET measures. Pearson correlation tests revealed no correlations with a magnitude greater than |0.5| of the changes of putamen EDVR or Kocc with changes of the motor functions measured by UPDRSIII scoring between baseline and month 3. This holds true for the overall primary efficacy sample (r=-0.162 [p=0.354] for EDVR and 0.106 [p=0.545] for Kocc), but also after stratification for cabergoline (r=-0.273 [p=0.290] for EDVR and 0.129 [p=0.621] for Kocc) and levodopa treatment (r=-0.018 [p=0.954] for EDVR and 0.140 [p=0.581 for Kocc).

Tolerability and safety

Tolerability and safety analyses were intent-to-treat. In general, both treatment regimes were well tolerated. None of the patients dropped out due to adverse events. 10 (27.8%) patients (7 on cabergoline and 3 on levodopa) reported a total of 16 incident adverse events during the study. Most frequently reported adverse events (occurring in at least 2 patients [5.6%]) included constipation (affecting 5 [29.4%] of patients in the cabergoline group and 0 [0.0%] of those in the levodopa group) and daytime sleepiness (3 [17.6%] and 1 [5.3%]). There were no adverse events due to PET scanning procedures. All but one adverse event were mild and one was judged as moderate, no serious adverse event occurred during the study. There were no clinically relevant changes in the results of laboratory tests, electrocardiograms, or vital signs in all participants.

e-References

e1. Oehme L, Perick M, Beuthien-Baumann B, et al. Comparison of dopamine turnover, dopamine influx constant and activity-ratio of striatum and occipital brain with 18F-DOPA-Brain-PET in normal controls and patients with Parkinson’s disease. Eur J Nucl Med Mol I 2011;38:1550–1559.

e2. Sossi V, de La Fuente-Fernandez R, Holden JE, et al. Increase in dopamine turnover occurs early in Parkinson's disease: evidence from a new modeling approach to PET 18 F-fluorodopa data. J Cereb Blood Flow Metab 2002;22:232-239.

e3. Hoffman JM, Melega WP, Hawk TC, et al. The effects of carbidopa administration on 6-[18F]fluoro-L-dopa kinetics in positron emission tomography. J Nucl Med 1992;33:1472-1477.

e4. Fuchtner F, Preusche S, Mading P, Zessin J, Steinbach J. Factors affecting the specific activity of [18F]fluoride from a [18O]water target. Nuklearmedizin 2008;47:116-119.

e5. Fuchtner F, Zessin J, Mading P, Wust F. Aspects of 6-[18F]fluoro-L-DOPA preparation. Deuterochloroform as a substitute solvent for Freon 11. Nuklearmedizin 2008;47:62-64.

e6. Langner J, Buhler P, Just U, Potzsch C, Will E, van den Hoff J. Optimized list-mode acquisition and data processing procedures for ACS2 based PET systems. Z Med Phys 2006;16:75-82.

e7. Buhler P, Just U, Will E, Kotzerke J, van den Hoff J. An accurate method for correction of head movement in PET. IEEE Trans Med Imaging 2004;23:1176-1185.

e8. Sossi V, Doudet DJ, Holden JE. A reversible tracer analysis approach to the study of effective dopamine turnover. J Cereb Blood Flow Metab 2001;21:469-476.

e9. Sossi V, Holden JE, de la Fuente-Fernandez R, Ruth TJ, Stoessl AJ. Effect of dopamine loss and the metabolite 3-O-methyl-[18F]fluoro-dopa on the relation between the 18F-fluorodopa tissue input uptake rate constant Kocc and the [18F]fluorodopa plasma input uptake rate constant Ki. J Cereb Blood Flow Metab 2003;23:301-309.

e10. Patlak CS, Blasberg RG. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. Generalizations. J Cereb Blood Flow Metab 1985;5:584-590.

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