Original Article

European Journal of Nuclear Medicine and Molecular Imaging

, Volume 38, Issue 12, pp 2228-2237

Statistical parametric maps of 18F-FDG PET and 3-D autoradiography in the rat brain: a cross-validation study

  • Elena PrietoAffiliated withNuclear Medicine Department, Clínica Universidad de Navarra
  • , María CollantesAffiliated withSmall Animal Imaging Research Unit, Center for Applied Medical Research (CIMA) and Clínica Universidad de Navarra
  • , Mercedes DelgadoAffiliated withBrain Mapping Unit, Universidad Complutense de Madrid
  • , Carlos JuriAffiliated withMovement Disorders Group, Neurosciences Division, Center for Applied Medical Research (CIMA)Department of Neurology and Neurosurgery, Clínica Universidad de NavarraCentro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Department of Neurology, Pontificia Universidad Católica de Chile
  • , Luis García-GarcíaAffiliated withBrain Mapping Unit, Universidad Complutense de Madrid
  • , Francisco MolinetAffiliated withSmall Animal Imaging Research Unit, Center for Applied Medical Research (CIMA) and Clínica Universidad de Navarra
  • , María E. Fernández-ValleAffiliated withMRI Research Center, Universidad Complutense de Madrid
  • , Miguel A. PozoAffiliated withBrain Mapping Unit, Universidad Complutense de Madrid
  • , Belén GagoAffiliated withMovement Disorders Group, Neurosciences Division, Center for Applied Medical Research (CIMA)Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)
    • , Josep M. Martí-ClimentAffiliated withNuclear Medicine Department, Clínica Universidad de Navarra
    • , José A. ObesoAffiliated withMovement Disorders Group, Neurosciences Division, Center for Applied Medical Research (CIMA)Department of Neurology and Neurosurgery, Clínica Universidad de NavarraCentro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)
    • , Iván PeñuelasAffiliated withNuclear Medicine Department, Clínica Universidad de NavarraSmall Animal Imaging Research Unit, Center for Applied Medical Research (CIMA) and Clínica Universidad de Navarra Email author 

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Abstract

Purpose

Although specific positron emission tomography (PET) scanners have been developed for small animals, spatial resolution remains one of the most critical technical limitations, particularly in the evaluation of the rodent brain. The purpose of the present study was to examine the reliability of voxel-based statistical analysis (Statistical Parametric Mapping, SPM) applied to 18F-fluorodeoxyglucose (FDG) PET images of the rat brain, acquired on a small animal PET not specifically designed for rodents. The gold standard for the validation of the PET results was the autoradiography of the same animals acquired under the same physiological conditions, reconstructed as a 3-D volume and analysed using SPM.

Methods

Eleven rats were studied under two different conditions: conscious or under inhalatory anaesthesia during 18F-FDG uptake. All animals were studied in vivo under both conditions in a dedicated small animal Philips MOSAIC PET scanner and magnetic resonance images were obtained for subsequent spatial processing. Then, rats were randomly assigned to a conscious or anaesthetized group for postmortem autoradiography, and slices from each animal were aligned and stacked to create a 3-D autoradiographic volume. Finally, differences in 18F-FDG uptake between conscious and anaesthetized states were assessed from PET and autoradiography data by SPM analysis and results were compared.

Results

SPM results of PET and 3-D autoradiography are in good agreement and led to the detection of consistent cortical differences between the conscious and anaesthetized groups, particularly in the bilateral somatosensory cortices. However, SPM analysis of 3-D autoradiography also highlighted differences in the thalamus that were not detected with PET.

Conclusion

This study demonstrates that any difference detected with SPM analysis of MOSAIC PET images of rat brain is detected also by the gold standard autoradiographic technique, confirming that this methodology provides reliable results, although partial volume effects might make it difficult to detect slight differences in small regions.

Keywords

Rat brain Positron emission tomography Three-dimensional autoradiography SPM