Objective: The need for age-adjusted and/or sex-adjusted reference values in dopamine transporter (DAT) and dopamine D2 receptor (D2R) imaging with single-photon emission computed tomography (SPECT) in a longitudinal study of parkinsonian diseases was investigated. We used two different image evaluation tools with a cross-sectional and longitudinal statistical approach.
Materials and methods: Baseline DAT and/or D2R SPECT were performed in 51 healthy controls (HC), age-matched to patients in an ongoing prospective study on idiopathic parkinsonism. Twenty-four HC were re-examined after 3 years and 21 HC were examined again after 5 years. SPECT was performed with 123I-FP-Cit and 123I-IBZM on a two-headed hybrid gamma camera. Regions of interest and volumes of interest (VOIs) were used for image evaluation. A cross-sectional and longitudinal statistical analysis was carried out.
Results: Fewer sex-based differences and less age dependency were seen in DAT SPECT uptake ratios compared with D2R SPECT uptake ratios and when comparing uptake ratios obtained with regions of interest against those with VOIs. In the cross-sectional analysis, a significant age-dependent decline was seen in women in both DAT and D2R uptakes with the VOI method but not in men with either evaluation method. In the longitudinal dataset, both a slight decline and increase over time were seen in DAT uptake; however, a general pattern of decrease was seen in both men and women in D2R uptake.
Conclusion: The choice of the image evaluation method can influence the pattern of sex-based and age-related differences. The results speak for the use of age-stratified reference values for women, in particular when using a VOI method.
aDepartment of Radiation Sciences, Diagnostic Radiology
bDepartments of Pharmacology and Clinical Neuroscience, Neurology
cDepartment of Radiation Sciences, Radiation Physics
dDepartment of Public Health and Clinical Medicine, Epidemiology and Global Health, Umeå University, Umeå
eDepartment of Molecular and Clinical Medicine, Gothenburg University, Gothenburg, Sweden
Correspondence to Susanna Jakobson Mo, MD, Department of Radiation Sciences, Diagnostic Radiology, Umeå University, 901 85 Umeå, Sweden Tel: +46 90 7851601; fax: +46 90 122303; e-mail: firstname.lastname@example.org
Received March 26, 2013
Accepted June 28, 2013