Objectives: 

We propose the development of a semi-automated analysis software tool for molecular images that allows the detection and quantification of the major areas of interest in the rat brain to study glucose consumption in aging.

Materials: 

Nine Wistar rats have been studied (five female -three young and two old-, and four male -two young and two old). All images were acquired using a Positron Emission Tomography scanner. The tracer 18F-FDG was injected intraperitoneally after anesthesia and PET was started 40 min after injection. The administered dose (FDG activity) was corrected for body weight. The result of each acquisition was a three-dimensional image, from which 72 axial, sagittal and coronal sections were extracted. Nine sequences of 72 PET images were studied from nine rats. The methodology described has four steps: a preprocessing of PET and atlas images, a coregistration of them, a semi-automatic segmentation of the regions of interest and a 3D reconstruction of these. Brain glucose uptake in these regions was quantified as SUV (Standardized Uptake Value). To compare SUV between young and old rats an unpaired student t test was used.

Results: 

SUV results show the effect of aging on glucose consumption in vivo by the brain of Wistar animals. There was a significant decrease in cerebral glucose consumption in old rats compared to young ones, regardless gender (male: 3.3±0.3 vs. 2.5±0.1 SUV, P<0.05; female: 5.0±1.4 vs. 2.6±0.9 SUV, P<0.05).

Conclusions: 

The tool allows the quantification of glucose uptake in ROIs of rat brain. Results show the accuracy of the tool to define ranges of variation in a population of young and old rats. These results show a decrease in glucose consumption in aging, previously reported.