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Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) Correlation of Histopathology and MRI in Prion Disease
Karin P Mente1, James K O'Donnell, Stephen E Jones
1Departments of *Neurology ‡Diagnostic Radiology ¶Quantitative Health Sciences, Cleveland Clinic Departments of †Radiology §Pathology **Neurology, University Hospitals Case Medical Center ∥National Prion Disease Pathology Surveillance Center #Department of Neuroradiology, Humanitas Research Hospital IRCCS, Milano, Italy.
Abstract:
Creutzfeldt-Jakob disease (CJD) and other prion diseases are rapidly progressive spongiform encephalopathies that are invariably fatal. Clinical features and magnetic resonance imaging, electroencephalogram, and cerebrospinal fluid abnormalities may suggest prion disease, but a definitive diagnosis can only be made by means of neuropathologic examination. Fluorodeoxyglucose positron emission tomography (FDG-PET) is not routinely used to evaluate patients with suspected prion disease. This study includes 11 cases of definite prion disease in which FDG-PET scans were obtained. There were 8 sporadic CJD cases, 2 genetic CJD cases, and 1 fatal familial insomnia case. Automated FDG-PET analysis revealed parietal region hypometabolism in all cases. Surprisingly, limbic and mesolimbic hypermetabolism were also present in the majority of cases. When FDG-PET hypometabolism was compared with neuropathologic changes (neuronal loss, astrocytosis, spongiosis), hypometabolism was predictive of neuropathology in 80.6% of cortical regions versus 17.6% of subcortical regions. The odds of neuropathologic changes were 2.1 times higher in cortical regions than subcortical regions (P=0.0265). A similar discordance between cortical and subcortical regions was observed between FDG-PET hypometabolism and magnetic resonance imaging diffusion weighted imaging hyperintensity. This study shows that there may be a relationship between FDG-PET hypometabolism and neuropathology in cortical regions in prion disease but it is unlikely to be helpful for diagnosis.
Insights
Fluorodeoxyglucose positron emission tomography (FDG-PET) scans in prion diseases revealed parietal hypometabolism and limbic hypermetabolism. While FDG-PET hypometabolism correlated with cortical neuropathology, it is unlikely to aid in diagnosing prion diseases.
Area of Science:
- Neurology
- Nuclear Medicine
- Pathology
Background:
- Prion diseases, including Creutzfeldt-Jakob disease (CJD), are fatal neurodegenerative disorders.
- Definitive diagnosis requires neuropathologic examination, as clinical and imaging findings are suggestive but not conclusive.
- Fluorodeoxyglucose positron emission tomography (FDG-PET) is not a standard diagnostic tool for suspected prion disease.
Purpose of the Study:
- To investigate the utility of FDG-PET in characterizing prion disease.
- To compare FDG-PET findings with neuropathologic changes and MRI in definite prion disease cases.
Main Methods:
- Analysis of FDG-PET scans from 11 patients with confirmed prion disease (8 sporadic CJD, 2 genetic CJD, 1 fatal familial insomnia).
- Automated analysis of FDG-PET scans to identify hypometabolic and hypermetabolic regions.
- Comparison of FDG-PET findings with neuropathologic data (neuronal loss, astrocytosis, spongiosis) and MRI diffusion-weighted imaging.
Main Results:
- All cases showed parietal hypometabolism on FDG-PET.
- A majority of cases exhibited limbic and mesolimbic hypermetabolism.
- FDG-PET hypometabolism predicted neuropathology in 80.6% of cortical regions versus 17.6% of subcortical regions.
- Cortical regions had a significantly higher likelihood (2.1 times) of showing neuropathologic changes compared to subcortical regions.
- A similar cortical-subcortical discordance was noted between FDG-PET hypometabolism and MRI findings.
Conclusions:
- FDG-PET may show a relationship between hypometabolism and cortical neuropathology in prion diseases.
- The diagnostic value of FDG-PET for prion disease is limited due to observed discordances and regional variations.
- Further research is needed to understand the role of FDG-PET in prion disease evaluation.
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