FDG-PET and ASL MRI identify largely overlapping hypermetabolic and hyperperfusion changes in limbic autoimmune encephalitis.

BACKGROUND: Arterial spin labeling (ASL) MRI has been anecdotally used to assess brain perfusion in autoimmune encephalitis (AE) and its relationship with [18F]FDG-PET dysmetabolism has been scarcely investigated.Considering the physiological coupling of metabolism and perfusion, we aimed to evaluate the degree of correspondence between ASL-MRI and [18F]FDG-PET in AE. METHODS: A retrospective cohort of five patients underwent ASL-MRI and [18F]FDG-PET during the acute stage and at follow-up. We assessed the presence of regions with hypermetabolism on [18F]FDG-PET and hyperperfusion on ASL-MRI and evaluated concordance and spatial overlap of these metrics. Clinical assessment scale in AE and modified Rankin Scale were obtained at baseline and follow-up. RESULTS: In two patients [18F]FDG-PET and ASL-MRI were unremarkable; in three patients there were anatomically overlapping areas of hypermetabolism and hyperperfusion (average DICE similarity coefficient 0.358). Following immunotherapy, metabolic and perfusion changes consistently demonstrated a progressive normalization, aligning with clinical improvement. CONCLUSIONS: We identified suboptimal anatomical correspondence of abnormalities assessed with [18F]FDG-PET and ASL-MRI. Hyperperfusion and hypermetabolism might reflect differently AE-related pathophysiological correlates, but they both demonstrate ability to monitor disease activity. ASL-MRI is a promising marker of disease activity in AE and a favorable alternative to [18F]FDG-PET due to its cost-effectiveness, safety, and wide availability.

The role of EEG and neuroimaging in the diagnosis of non-convulsive status epilepticus in Subacute Encephalopathy with Seizures in Alcoholics (SESA syndrome): a case report and overview of the literature.

Epileptic seizures are frequently associated with liver dysfunction and alcoholism. Subacute encephalopathy with seizures in chronic alcoholics (SESA) is an underrecognized condition with peculiar clinical, EEG and neuroradiological features.We report the case of a 58-year-old man with previous alcohol use disorder (AUD) and acute-on chronic liver failure on alcohol-related cirrhosis, referred for urgent Orthotopic Liver Transplantation evaluation. The patient presented with delirium, aphasia and progressive deterioration of consciousness leading to intensive care unit admission. EEG showed slow activity with superimposed lateralized periodic discharges (LPDs) over the left temporo-occipital regions and ictal discharges with focal motor phenomena, consistent with focal status epilepticus. Antiseizure treatment with lacosamide and levetiracetam was administered with progressive improvement of consciousness.Brain MRI disclosed T2/FLAIR areas of hyperintensity in the left pulvinar and T2/FLAIR hyperintensity with corresponding DWI hyperintensity in the left hippocampal cortex, suggestive of post/peri-ictal excitotoxic changes with anatomical correspondence to focal LPDs distribution. SWI demonstrated decreased prominence of cortical veins in the left temporo-occipital region consistent with increased venous blood oxygenation in compensatory hyperperfusion.In conclusion, SESA should be suspected in the differential diagnosis of patients with AUD presenting with focal neurological deficits, seizures and focal EEG abnormalities. In this context, EEG and brain MRI represent useful tools with both diagnostic and prognostic value.

Autoimmune encephalitis: what the radiologist needs to know.

Autoimmune encephalitis is a relatively novel nosological entity characterized by an immune-mediated damage of the central nervous system. While originally described as a paraneoplastic inflammatory phenomenon affecting limbic structures, numerous instances of non-paraneoplastic pathogenesis, as well as extra-limbic involvement, have been characterized. Given the wide spectrum of insidious clinical presentations ranging from cognitive impairment to psychiatric symptoms or seizures, it is crucial to raise awareness about this disease category. In fact, an early diagnosis can be dramatically beneficial for the prognosis both to achieve an early therapeutic intervention and to detect a potential underlying malignancy. In this scenario, the radiologist can be the first to pose the hypothesis of autoimmune encephalitis and refer the patient to a comprehensive diagnostic work-up - including clinical, serological, and neurophysiological assessments.In this article, we illustrate the main radiological characteristics of autoimmune encephalitis and its subtypes, including the typical limbic presentation, the features of extra-limbic involvement, and also peculiar imaging findings. In addition, we review the most relevant alternative diagnoses that should be considered, ranging from other encephalitides to neoplasms, vascular conditions, and post-seizure alterations. Finally, we discuss the most appropriate imaging diagnostic work-up, also proposing a suggested MRI protocol.