Influence of mild hyperglycemia on cerebral FDG distribution patterns calculated by statistical parametric mapping

Area of Science:

• Neuroimaging
• Nuclear Medicine
• Metabolic Imaging

Background:

• Clinical 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) studies can be affected by patient hyperglycemia.
• Fasting requirements are crucial for accurate cerebral FDG uptake interpretation.

Purpose of the Study:

• To investigate the impact of mild hyperglycemia (110-160 mg/dl) on cerebral FDG distribution patterns.
• To evaluate the influence of different reference regions in statistical parametric mapping (SPM) analysis under hyperglycemic conditions.

Main Methods:

• 19 healthy subjects underwent two FDG-PET scans: one fasting, one mildly hyperglycemic.
• Statistical parametric mapping (SPM) and region of interest (ROI) analyses were performed.
• Three reference regions were used: SPM global brain (SPMgb), gray/white matter (MRIgw), and cerebellar cortex (Cbll).

Main Results:

• Mild hyperglycemia significantly reduced FDG uptake in gray matter regions (frontal, temporal, parietal cortices, posterior cingulate, precuneus) when using SPMgb or MRIgw references.
• These gray matter decreases under hyperglycemia mimicked patterns seen in Alzheimer's disease.
• FDG uptake increased in white matter (centrum semiovale) across all reference-based analyses.
• When the cerebellar cortex (Cbll) was used as the reference, the observed gray matter decrease patterns disappeared.

Conclusions:

• Mild hyperglycemia alters cerebral FDG distribution patterns in SPM analysis.
• Using SPMgb or MRIgw as reference regions can lead to misinterpretation, potentially mimicking Alzheimer's disease.
• The cerebellar cortex (Cbll) is a recommended reference region under mild hyperglycemia to accurately detect decreased FDG uptake.
• Careful control of diet, monitoring of hyperglycemia, and optimization of reference regions are crucial for accurate clinical FDG-PET interpretation, especially for early Alzheimer's disease diagnosis.