Brain perfusion SPECT in the mouse: normal pattern according to gender and age

Area of Science:

• Preclinical neuroscience
• Nuclear medicine imaging
• Cerebrovascular research

Background:

• Regional cerebral blood flow (rCBF) is a key indicator of neuronal activity and disease diagnosis.
• Mouse models are crucial for preclinical research, necessitating in vivo rCBF measurement techniques.
• Small animal SPECT offers high spatial resolution and sensitivity for mouse brain imaging.

Purpose of the Study:

• To evaluate the feasibility of mouse brain perfusion SPECT using Tc-99m-HMPAO.
• To assess age and gender impacts on regional Tc-99m-HMPAO uptake patterns.
• To compare Tc-99m-HMPAO with Tc-99m-ECD for mouse brain perfusion SPECT.

Main Methods:

• Comparison of Tc-99m-HMPAO and Tc-99m-ECD whole-brain kinetics via dynamic planar scans in 10 mice.
• SPECT imaging in 18 juvenile and adult mice using nanoSPECT/CTplus.
• Stereotactic normalization of SPECT images to a 3D MRI atlas for ROI analysis and voxel-wise testing.

Main Results:

• Tc-99m-HMPAO demonstrated suitable brain retention, unlike Tc-99m-ECD which showed rapid washout.
• Increased HMPAO uptake with age in the neocortex and hippocampus; decreased uptake in the midbrain.
• Significant left-hemisphere lateral asymmetry in neocortical HMPAO uptake in both juvenile and adult mice.

Conclusions:

• High-resolution SPECT with Tc-99m-HMPAO is a viable method for preclinical mouse rCBF studies.
• The technique reveals age-related rCBF changes during late maturation and lateral asymmetry in the mouse brain.
• Tc-99m-ECD is unsuitable for mouse brain SPECT due to rapid clearance, indicating species-specific differences.