FDG μPET Fails to Detect a Disease-Specific Phenotype in Rats Transgenic for Huntington's Disease – A 15 Months...

Area of Science:

• Neuroscience
• Medical Imaging
• Animal Models

Background:

• FDG-PET detects hypometabolism in Huntington's disease (HD).
• Previous studies in transgenic HD rats showed conflicting results regarding FDG-PET detectability of HD phenotypes.
• Limited sample sizes and analysis scope (whole-brain or striatum) were noted in prior research.

Purpose of the Study:

• To investigate if FDG-PET can detect HD phenotypes in a larger cohort of transgenic HD (tgHD) rats compared to wild-type (wt) rats.
• To determine the onset and effect sizes of metabolic changes over time using detailed regional analysis.
• To clarify conflicting findings from previous FDG-PET studies in HD rat models.

Main Methods:

• A longitudinal study involving 19 tgHD and 20 wt rats (mixed gender) aged 5, 10, 15, and 20 months.
• Small animal FDG-μPET and MRI scans were performed, with regions of interest (ROIs) defined on MRI and transferred to PET.
• Analysis included manual ROI measurements and hypothesis-free voxel-by-voxel SPM analysis of normalized FDG uptake.

Main Results:

• FDG uptake demonstrated changes over time in both tgHD and wt rats.
• No consistent differences in FDG uptake were observed between tgHD and wt rats across manual ROI and SPM analyses.
• This suggests FDG-PET did not reveal a distinct metabolic phenotype in this rat model within the studied age range.

Conclusions:

• FDG-μPET imaging did not detect significant alterations in this transgenic rat model of Huntington's disease at the investigated ages.
• Further research is needed, potentially exploring different age groups or alternative imaging biomarkers for neuronal degeneration.
• The findings highlight limitations of current FDG-PET protocols for detecting early HD-related metabolic changes in this specific animal model.