Descripción de una serie de pacientes con diagnóstico de enfermedad priónica

The Role of PET Imaging in Patients with Prion Disease: A Literature Review

Prion diseases are rare, rapidly progressive, and fatal incurable degenerative brain disorders caused by the misfolding of a normal protein called PrPC into an abnormal protein called PrPSc. Their highly variable clinical presentation mimics various degenerative and non-degenerative brain disorders, making diagnosis a significant challenge for neurologists. Currently, definitive diagnosis relies on post-mortem examination of nervous tissue to detect the pathogenic prion protein. The current diagnostic criteria are limited. While structural magnetic resonance imaging (MRI) remains the gold standard imaging modality for Creutzfeldt-Jakob disease (CJD) diagnosis, positron emission tomography (PET) using 18fluorine-fluorodeoxyglucose (18F-FDG) and other radiotracers have demonstrated promising potential in the diagnostic assessment of prion disease. In this context, a comprehensive and updated review exclusively focused on PET imaging in prion diseases is still lacking. We review the current value of PET imaging with 18F-FDG and non-FDG tracers in the diagnostic management of prion diseases. From the collected data, 18F-FDG PET mainly reveals cortical and subcortical hypometabolic areas in prion disease, although fails to identify typical pattern or laterality abnormalities to differentiate between genetic and sporadic prion diseases. Although the rarity of prion diseases limits the establishment of a definitive hypometabolism pattern, this review reveals some more prevalent 18F-FDG patterns associated with each disease subtype. Interestingly, in both sporadic and genetic prion diseases, the hippocampus does not show significant glucose metabolism alterations, appearing as a useful sign in the differential diagnosis with other neurodegenerative disease. In genetic prion disease forms, PET abnormality precedes clinical manifestation. Discordant diagnostic value for amyloid tracers among different prion disease subtypes was observed, needing further investigation. PET has emerged as a potential valuable tool in the diagnostic armamentarium for CJD. Its ability to visualize functional and metabolic brain changes provides complementary information to structural MRI, aiding in the early detection and confirmation of CJD.

Can insomnia be fatal? An Australian case of fatal familial insomnia

Fatal familial insomnia (FFI) is a rare prion disease with autosomal dominant inheritance. Currently, there is only one published case study of FFI in Australia. FFI is universally fatal, with the disease duration ranging from 8 to 72 months. Clinically, it manifests with disordered sleep-wake cycle, dysautonomia, motor disturbances and neuropsychiatric disorders. We describe a case of FFI detailing the investigative process, including the importance of sleep assessment and polysomnography in obtaining a diagnosis.

Combined findings of FDG-PET and arterial spin labeling in sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is a fatal progressive neurodegenerative disease. Multimodal approaches, including electroencephalogram, diffusion-weighted imaging (DWI) of brain MRI, and cerebrospinal fluid biomarkers, have been applied to increase the diagnostic accuracy of sCJD. Although previous studies suggested DWI could be the most useful modality for sCJD diagnosis, whether metabolism changes underlying in sCJD are still poorly understood. To the best of our knowledge, there are only one case using the technique of arterial spin labeling (ASL) to detection and follow-up of perfusion changes in CJD. Herein, we described a 71-year-old woman presented with progressive cognitive decline, behavioral and psychological symptoms for two months. The patient died one month later after her admission. As far as we know, this is the first report using the combination of fluorodeoxyglucose positron emission tomography and ASL to explore the metabolism changes in sCJD. Our case exemplifies the difficulty clinicians may face in the diagnosis of sCJD.

The Sole Initial Imaging Finding in Creutzfeldt-Jacob Disease: Focal FDG-PET Hypometabolism

Laboratory studies such as electroencephalography, cerebrospinal fluid examination and diffusion-weighted magnetic resonance imaging (DWI-MRI) are valuable in the diagnosis of Creutzfeldt-Jacob disease (CJD),. However, these laboratory studies may not show the characteristic findings in the very early stage of the disease. Here, we present a case of CJD who had atypical neurologic presentation initially and had only a focal parietal 2-(18F) fluorodeoxyglucose (FDG) positron emission tomography (PET) hypometabolism as the sole imaging abnormality at the beginning. The patient progressed rapidly, and showed typical neurological findings for CJD. The brain MRI was performed two weeks after the FDG-PET study, finally demonstrated increased signal intensity in DWI in caudat nucleus, putamen, and cerebral cortex, especially on left parietal region. Imaging methods demonstrating functional alterations in the brain should be obtained in the early period in patients with normal MRI suspected having CJD. Repeating DWI could also be an effective diagnostic approach.

Amyloid- and FDG-PET in sporadic Creutzfeldt-Jakob disease: Correlation with pathological prion protein in neuropathology

INTRODUCTION

The role of positron emission tomography (PET) in Creutzfeldt-Jakob disease is less defined than in other neurodegenerative diseases. We studied the correlation between the uptake of ¹⁸F-florbetaben and ¹⁸F-fluorodeoxyglucose with pathological prion protein deposition in histopathology in a case.

METHODS

A patient with 80 y old with a rapid neurological deterioration with a confirmed diagnosis of CJD was studied. PET and MRI studies were performed between 13-20 d before the death. A region of interest analysis was performed using Statistical Parametric Mapping.

RESULTS

MRI showed atrophy with no other alterations. FDG-PET showed extensive areas of hypometabolism including left frontoparietal lobes as well as bilateral thalamus. Correlation between uptake of ¹⁸F-florbetaben and pathological prion protein deposition was r = 0.786 (p < 0.05). Otherwise, correlation between uptake of ¹⁸F-FDG and pathological prion protein was r = 0.357 (p = 0.385). Immunohistochemistry with β-amyloid did not show amyloid deposition or neuritic plaques.

CONCLUSIONS

Our study supports the use of FDG-PET in the assessment of CJD. FDG-PET may be especially useful in cases of suspected CJD and negative MRI. Furthermore, this case report provides more evidence about the behavioral of amyloid tracers, and the possibility of a low-affinity binding to other non-amyloid proteins, such as the pathological prion protein, is discussed.

Integrated (18)F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging ((18)F-FDG PET/MRI), a multimodality approach for comprehensive evaluation of dementia patients: A pictorial essay

Dementia, caused by irreversible neurodegenerative disorders such as Alzheimer's disease or reversible non-degenerative conditions, is rapidly becoming one of the most alarming health problems in our aging society. This cognitive disorder associated with a multitude of clinical differentials with overlapping clinical, pathological, and imaging features is difficult to diagnose and treat, as it often presents late after significant neuronal damage has already occurred. Novel disease-modifying treatments being developed will have to be corroborated with innovative imaging biomarkers so that earlier reliable diagnosis can be made and treatment initiated upon. Along with new specific PET radiotracers, integrated PET/MRI with combined methodological advantage and simultaneously acquired structural-cum-functional information may help achieve this goal. The present pictorial essay details our experiences with PET/MRI in dementing disorders, along with reviewing recent advances and future scope.