Anales de la RANM

36 A N A L E S R A N M R E V I S T A F U N D A D A E N 1 8 7 9 S U P L E M E N T O I SIMPOSIO · JÓVENES INVESTIGADORES Libro de Abstracts An RANM. 2021;138(03).supl01: 36 - 54 Consequently, Alzheimer´s disease is now the main medical problem and the leading cause of death in this population. Increasing evidence from patholo- gical and biomarker studies show a very similar pathophysiology and natural history to that described in sporadic and autosomal dominant Alzheimer´s disease. However, underdiagnosis is frequent due to a lack of awareness and diagnostic challenges posed by the intellectual disability associated with Down syndrome. Biomarkers, including those in plasma, have shown very promising results in diagnosis, but are currently only used in rare research settings. Most importantly, there are no treatments to prevent the disease despite the fact Down syndrome is probably the best population in which to conduct Alzheimer’s disease prevention trials as it is a unique and relatively prevalent population with a known aetiology. Research in Down syndrome is essential to improve the quality of life and find treatments for Alzheimer´s disease that might benefit both the Down syndrome and the general population. Introducción: Los métodos de cuantificación de amiloide con trazadores PET requieren de una resonancia magnética estructural (RM) para la normalización espacial, y usan diferentes regiones de referencia para escalar la imagen. Además, los diferentes trazadores tienen distintos umbrales de positividad. Este trabajo proporciona una nueva medida estandarizada para la cuantifica- ción del amiloide que salva estas limitaciones: el AMYQ. Métodos : Seleccionamos todas las imágenes PET de amiloide con trazadores de Flúor (F18) de la “Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing” (AIBL) y “Alzheimer’s Disease Neuroimaging Initiative” (ADNI) con la correspondiente RM estructural. Una submuestra disponía también de datos neuropatológicos. Se creó una plantilla de PET de amiloide usando análisis de componentes principales (PCA). Mediante esta plantilla PET, se normalizaron las imágenes PET individuales y se calculó el AMYQ. Comparamos el rendimiento de AMYQ con la escala Centiloide en el diagnóstico clínico y neuropatológico. Además, evaluamos la habilidad del AMYQ de discriminar la positividad de PET cuantificada con RM. Resultados : AMYQ se relacionó con las medidas neuropatológicas de amiloide y tuvo un rendimiento excelente para discriminar controles de pacientes con enfermedad de Alzheimer (área bajo la curva = 0.86). AMYQ se asoció con el centiloide en la muestra combinada de los tres trazadores (coeficiente de correlación intra-clase = 0.88) y mostró una área bajo la curva de entre 0.94 y 0.99 para discriminar la positividad de PET usando diferentes umbrales de Centiloide. Conclusiones : AMYQ es un nuevo índice estándar de carga de amiloide que no requiere de RM y es aplicable a los tres trazadores 18F de PET de amiloide. Introduction: Positron emission tomography (PET) amyloid quantification methods require magnetic resonance imaging (MRI) for spatial registration and use of different a priori reference regions to scale the images. Furthermore, different tracers have distinct thresholds for positivity. This work provides a new standard measure of amyloid burden to overcome these limitations: AMYQ. Methods: We selected all 18Fluor-radiolabeled amyloid PET scans from AIBL and ADNI and the corresponding structural MRI. A subset also had neuropathological data. We created an amyloid PET template using a principal component analysis (PCA). Through this PET template, individual amyloid PET scans were spatially normalized and AMYQ was computed. We compared the performance of AMYQ with the Centiloid scale on clinical and neuropatho- logical diagnostic performance. Additionally, we assessed the perfomrance of AMYQ in discriminating amyloid PET positive from amyloid PET negative quantified with the MRI. Results: AMYQ was related with amyloid neuropathological burden and had excellent diagnostic performance to discriminate controls from patients with Alzheimer’s disease (AD) (area under the curve = 0.86). AMYQ had a high agreement with the Centiloid scale in the combined sample of the three tracers (intraclass correlation coefficient = 0.88) and showed an AUC between 0.94 and 0.99 to discriminate PET positivity when using different Centiloid cutoffs. Conclusions: AMYQ is a new standard index of amyloid burden that do not require MRI and is applicable to the three 18Fluor-radiolabeled amyloid tracers. AMYQ: UN ÍNDICE INDEPENDIENTE DE RM PARA ESTANDARIZAR LA CARGA DE AMILOIDE EN EL CEREBRO AMYQ: AN MR I-I NDEPENDENT I NDEX TO STAN- DARD I ZE AMYLO I D LOAD I N THE BRA I N Jordi Pegueroles 1,3 , Eduard Vilaplana 1,3 , Daniel Al- colea 1,3 , Victor Montal 1,3 , Alexandre Bejanin 1,3 , Mateus Aranha 1,3 , Miguel Angel Santos-Santos 1,3 , Ignasi Car- rió 2 , Valle Camacho 2 , Rafael Blesa 1,3 , Alberto Lleó 1,3 , Juan Fortea 1,3 1 Sant Pau Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Biomedical Research Institute Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain 2 Department of Nuclear Medicine, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain 3 Centro de Investigación Biomédica en Red sobre Enferme- dades Neurodegenerativas (CIBERNED),Madrid, Spain