Una imagen PET amiloide estática del primer minuto (FMF) se correlaciona con [18F]FDG PET en pacientes con afasia progresiva primaria / Static first-minute-frame (FMF) PET imaging after 18F-labeled amyloid tracer injection is correlated to [18F]FDG PET in patients with primary progressive aphasia

Objetivo Estudiar la correlación entre una imagen PET estática del primer minuto (FMF) adquirida con radiotrazadores de amiloide marcados con flúor-18 y la PET cerebral con [18F]FDG en pacientes con afasia primaria progresiva (APP). Material y métodos La cohorte de estudio incluyó a 17 pacientes diagnosticados de APP con la siguiente distribución: 9APP variante no fluente, 4APP variante logopénica, 1APP variante semántica, 3APP inclasificables. Se extrajeron los SUVR regionales de las FMF y sus correspondientes imágenes PET con [18F]FDG y se calcularon los coeficientes de correlación de Pearson. Resultados Los SUVR de ambas imágenes mostraron patrones similares de alteración cerebral regional. Los análisis de correlación intrapaciente dieron como resultado un coeficiente medio de r=0,94 ±0,06. Los coeficientes de correlación regional entre pacientes de la cohorte del estudio fueron superiores a 0,81. Las subcohortes específicas según el radiotrazador y la variante de APP no mostraron diferencias en la similitud de las imágenes. Conclusiones La FMF estática podría ser una alternativa válida a la PET dinámica de amiloide en fase inicial propuesta en la literatura, así como un biomarcador de neurodegeneración para el diagnóstico y la clasificación de la APP en los estudios de PET amiloide (AU)

Objective To study the correlation between a static PET image of the first-minute-frame (FMF) acquired with 18F-labeled amyloid-binding radiotracers and brain [18F]FDG PET in patients with primary progressive aphasia (PPA). Material and methods The study cohort includes 17 patients diagnosed with PPA with the following distribution: 9nonfluent variant PPA, 4logopenic variant PPA, 1semantic variant PPA, 3unclassifiable PPA. Regional SUVRs are extracted from FMFs and their corresponding [18F]FDG PET images and Pearson's correlation coefficients are calculated. Results SUVRs of both images show similar patterns of regional cerebral alterations. Intrapatient correlation analyses result in a mean coefficient of r=.94 ±.06. Regional interpatient correlation coefficients of the study cohort are greater than 0.81. Radiotracer-specific and variant-specific subcohorts show no difference in the similarity between the images. Conclusions The static FMF could be a valid alternative to dynamic early-phase amyloid PET proposed in the literature, and a neurodegeneration biomarker for the diagnosis and classification of PPA in amyloid PET studies (AU)

Actualización en el diagnóstico de la encefalitis / Update on the diagnosis of encephalitis

Las encefalitis autoinmunes son procesos inflamatorios cerebrales que se clasifican en dos grandes grupos según el mecanismo patogénico subyacente: las mediadas por anticuerpos vs. antígenos intracelulares (paraneoplásicas) y las mediadas por anticuerpos frente a los antígenos extracelulares o de superficie neuronal. Las manifestaciones clínicas son muy variadas y poco específicas. Las pruebas complementarias incluidas en el diagnóstico clínico de la encefalitis autoinmune incluyen, entre otras, la determinación de anticuerpos en suero o en líquido cefalorraquídeo y la resonancia magnética (RM). La RM puede presentar patrones característicos como la afectación mesial del temporal, aunque en determinados casos puede ser normal. La imagen de tomografía por emisión de positrones (PET/TC) con 18F-Fluorodeoxiglucosa (18F-FDG PET/TC) puede ser de gran utilidad en los casos de encefalitis autoinmunes paraneoplásicas para encontrar el tumor primario. En los casos de encefalitis autoinmunes mediadas por anticuerpos frente a los antígenos extracelulares, la 18F-FDG PET/TC presenta unos patrones que pueden ayudar al diagnóstico clínico. Esta colaboración especial pretende presentar de forma clara y de fácil comprensión las características clínicas de la encefalitis autoinmune, las dificultades en el diagnóstico clínico y los patrones observados en la RM y en la 18F-FDG PET/TC (AU)

Autoimmune encephalitis are brain inflammatory processes that are classified into two main groups according to the underlying pathogenic mechanism: antibodies to intracellular antigens (paraneoplastic) and antibodies to extracellular or neuronal surface antigens. The clinical manifestations of autoimmune encephalitis are very varied and non-specific. Complementary tests included in its clinical diagnosis include determination of antibodies in serum or cerebrospinal fluid and magnetic resonance imaging (MRI). MRI may show characteristic patterns such as mesial temporal involvement, although in some cases it may be normal or non-specific. 18F-Fluorodeoxyglucose PET/CT (18F-FDG PET/CT) imaging may be helpful in cases of paraneoplastic autoimmune encephalitis to find the primary tumor. In autoimmune encephalitis mediated by antibodies to extracellular antigens, 18F-FDG PET/CT shows distinctive patterns that can aid clinical diagnosis. This special collaboration aims to present in a clear and easy-to-understand way, the clinical features of autoimmune encephalitis, the difficulties in clinical diagnosis and the patterns seen on MRI and 18F-FDG PET/CT (AU)

Update on the diagnosis of encephalitis.

Autoimmune encephalitis are brain inflammatory processes that are classified into two main groups according to the underlying pathogenic mechanism: antibodies to intracellular antigens (paraneoplastic) and antibodies to extracellular or neuronal surface antigens. The clinical manifestations of autoimmune encephalitis are very varied and non-specific. Complementary tests included in its clinical diagnosis include determination of antibodies in serum or cerebrospinal fluid and magnetic resonance imaging (MRI). MRI may show characteristic patterns such as mesial temporal involvement, although in some cases it may be normal or non-specific. 18F-Fluorodeoxyglucose PET/CT (18F-FDG PET/CT) imaging may be helpful in cases of paraneoplastic autoimmune encephalitis to find the primary tumor. In autoimmune encephalitis mediated by antibodies to extracellular antigens, 18F-FDG PET/CT shows distinctive patterns that can aid clinical diagnosis. This continuing education aims to present in a clear and easy-to-understand way, the clinical features of autoimmune encephalitis, the difficulties in clinical diagnosis and the patterns seen on MRI and 18F-FDG PET/CT.

Neumonía vírica bilateral por COVID-19 como hallazgo casual en 18F-FDG-PET-TC de estadificación de paciente con melanoma gemelar derecho / Bilateral viral pneumonia by COVID-19 as a chance finding in staging with 18F-FGD-PET/CT of patient with right calf melanoma

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Relevancia de la cuantificación en los estudios PET cerebrales con 18F-FDG / Relevance of quantification in brain PET studies with 18F-FDG

La inclusión de la PET 18F-FDG como biomarcador en los criterios de diagnóstico clínico de enfermedades neurodegenerativas y su indicación en el estudio precirugía en la epilepsia resistente a los fármacos permiten mejorar la especificidad del diagnóstico. La interpretación clásica de los estudios PET neurológicos se ha abordado de forma cualitativa, aunque en la última década hemos sido testigos del auge en los sistemas de evaluación cuantitativa. Este desarrollo técnico es de vital importancia en la práctica clínica, ya que mejora la especificidad y la reproducibilidad y reduce el efecto dependiente del observador derivado del análisis visual. Consideramos que es conveniente exponer la complejidad de las técnicas de procesamiento de imagen empleadas, lo que permitirá al especialista en Medicina Nuclear conocer sus ventajas e inconvenientes a la hora de incluirlas en la práctica clínica diaria

The inclusion of 18F-FDG PET as a biomarker in the diagnostic criteria of neurodegenerative diseases and its indication in the presurgical assessment for drug-resistant epilepsies allow to improve specificity of these diagnosis. The traditional interpretation of neurological PET studies has been performed qualitatively, although in the last decade, several quantitative evaluation methods have emerged. This technical development has become relevant in clinical practice, improving specificity, reproducibility and reducing the interrater reliability derived from visual analysis. In this article we update/review the main imaging processing techniques currently used. This may allow the Nuclear Medicine physician to know their advantages and disadvantages when including these procedures in daily clinical practice

Relevance of quantification in brain PET studies with 18F-FDG. / Relevancia de la cuantificación en los estudios PET cerebrales con 18F-FDG.

The inclusion of 18F-FDG PET as a biomarker in the diagnostic criteria of neurodegenerative diseases and its indication in the presurgical assessment for drug-resistant epilepsies allow to improve specificity of these diagnosis. The traditional interpretation of neurological PET studies has been performed qualitatively, although in the last decade, several quantitative evaluation methods have emerged. This technical development has become relevant in clinical practice, improving specificity, reproducibility and reducing the interrater reliability derived from visual analysis. In this article we update/review the main imaging processing techniques currently used. This may allow the Nuclear Medicine physician to know their advantages and disadvantages when including these procedures in daily clinical practice.

PET amiloide en enfermedades neurodegenerativas que cursan con demencia / Amyloid PET in neurodegenerative diseases with dementia

La enfermedad de Alzheimer (EA) es una enfermedad neurodegenerativa que se caracteriza por un deterioro cognitivo progresivo y pérdida de memoria, siendo la causa más común de demencia. Los hallazgos anatomopatológicos de la EA son los depósitos de Aβ amiloide y proteína Tau, que producen disfunción sináptica y muerte neuronal. La PET amiloide es una técnica útil, disponible y no invasiva que nos proporciona información in vivo del depósito amiloide. En las últimas revisiones de los criterios diagnósticos de la EA se definen e incorporan los biomarcadores, que se clasifican en biomarcadores fisiopatológicos o de diagnóstico (aumento de la retención fibrilar amiloide observada por PET o disminución del péptido Aβ1-42 y elevación de las proteínas T-Tau y F-Tau en el LCR) y biomarcadores de neurodegeneración o topográficos (disminución del metabolismo temporoparietal en la PET-FDG y atrofia temporal medial en la RM). Recientemente se han creado unas recomendaciones específicas para la correcta utilización de los biomarcadores, donde se incluye la PET amiloide: deterioro cognitivo persistente/progresivo, deterioro cognitivo atípico, deterioro cognitivo de inicio precoz y diagnóstico diferencial entre EA y otras enfermedades neurodegenerativas que cursan con demencia. Nuevos estudios de investigación y ensayos clínicos están utilizando la PET amiloide en la evaluación y el desarrollo de nuevas terapias para la EA, así como para el estudio de otras enfermedades neurodegenerativas que cursan con demencia. En este trabajo revisamos algunos conceptos generales y profundizamos en el uso de esta nueva técnica y su relación con las enfermedades neurodegenerativas y el resto de las técnicas diagnósticas

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary tangles are a neuropathological hallmark of AD that produces synaptic dysfunction and culminates later in neuronal loss. Amyloid PET is a useful, available and non-invasive technique that provides in vivo information about the cortical amyloid burden. In the latest revised criteria for the diagnosis of AD biomarkers were defined and integrated: pathological and diagnostic biomarkers (increased retention on fibrillar amyloid PET or decreased Aβ1-42 and increased T-Tau or P-Tau in CSF) and neurodegeneration or topographical biomarkers (temporoparietal hypometabolism on 18F-FDG PET and temporal atrophy on MRI). Recently specific recommendations have been created as a consensus statement on the appropriate use of the imaging biomarkers, including amyloid PET: early-onset cognitive impairment/dementia, atypical forms of AD, mild cognitive impairment with early age of onset, and to differentiate between AD and other neurodegenerative diseases that occur with dementia. Amyloid PET is also contributing to the development of new therapies for AD, as well as in research studies for the study of other neurodegenerative diseases that occur with dementia where the deposition of Aβ amyloid is involved in its pathogenesis. In this paper, we review some general concepts and study the use of amyloid PET in depth and its relationship with neurodegenerative diseases and other diagnostic techniques

Amyloid PET in neurodegenerative diseases with dementia. / PET amiloide en enfermedades neurodegenerativas que cursan con demencia.

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary tangles are a neuropathological hallmark of AD that produces synaptic dysfunction and culminates later in neuronal loss. Amyloid PET is a useful, available and non-invasive technique that provides in vivo information about the cortical amyloid burden. In the latest revised criteria for the diagnosis of AD biomarkers were defined and integrated: pathological and diagnostic biomarkers (increased retention on fibrillar amyloid PET or decreased Aß1-42 and increased T-Tau or P-Tau in CSF) and neurodegeneration or topographical biomarkers (temporoparietal hypometabolism on 18F-FDG PET and temporal atrophy on MRI). Recently specific recommendations have been created as a consensus statement on the appropriate use of the imaging biomarkers, including amyloid PET: early-onset cognitive impairment/dementia, atypical forms of AD, mild cognitive impairment with early age of onset, and to differentiate between AD and other neurodegenerative diseases that occur with dementia. Amyloid PET is also contributing to the development of new therapies for AD, as well as in research studies for the study of other neurodegenerative diseases that occur with dementia where the deposition of Aß amyloid is involved in its pathogenesis. In this paper, we review some general concepts and study the use of amyloid PET in depth and its relationship with neurodegenerative diseases and other diagnostic techniques.