PET-CT en el carcinoma anaplásico de tiroides y otros subtipos histológicos agresivos / PET-CT in anaplastic thyroid carcinoma and other aggressive histological subtypes

Introducción y objetivo:Los subtipos histológicos agresivos de cáncer de tiroides son menos frecuentes y tienen peor pronóstico que los bien diferenciados (CDT). Los subtipos agresivos más importantes son el carcinoma de células de Hürthle (CCH), el carcinoma anaplásico y el pobremente diferenciadoEn esta revisión vamos a hablar del papel del PET-CT, especialmente con 18F-FDG, en estas estirpes histológicas agresivas, así como en subtipos agresivos de CDT (células altas, esclerosante difuso…) y en el carcinoma de tiroides refractario al radioyodo.Síntesis:Aunque la principal indicación del PET con 18F-FDG en el cáncer de tiroides es la sospecha de recidiva, en pacientes con CDT con tiroglobulina sérica elevada y rastreo corporal total (RCT) con radioyodo negativo, esta técnica tiene crecientes aplicaciones en el CDT.Así mismo, el PET con 18F-FDG también es una herramienta diagnóstica eficiente en el estudio del carcinoma anaplásico, el pobremente diferenciado y otras estirpes histológicas agresivas.Es recomendado en las guías clínicas actuales como parte de la estadificación inicial en cánceres de tiroides anaplásico, pobremente diferenciados y CCH invasivo. Y cada vez se emplea más en otras indicaciones como valoración pronóstica, de la respuesta al tratamiento, e incluso durante el seguimiento de pacientes de alto riesgo.El empleo de otros trazadores para PET como el 68Ga-PSMA y el 68Ga-DOTATATE no han demostrado claramente su beneficio clínico frente a la 18F-FDG. Suelen limitarse a casos en los que sea necesaria la valoración de la densidad de receptores de análogos de somatostatina y PSMA previa a terapia metabólica. (AU)

Introduction and objective: The aggressive histological subtypes of thyroid cancer are less common and have a worse prognosis than well –differentiated ones (DTC). The most important aggressive subtypes are Hürtle cell carcinoma (CHH), anaplasic and poorly differentiated carcinoma. In this review, we are going to evaluate the role of PET-CT, especially with 18F-FDG, in these aggressive histological lines, as well as in aggressive subtypes of DTC (tall cells, diffuse sclerosing...) and in radioiodine-refractory differentiated thyroid carcinoma. Synthesis: Although the main indication for 18F-FDG PET in thyroid cancer is suspected recurrence, in patients with DTC with elevated serum thyroglobulin and radioiodine-negative whole-body scan (WBS), this technique has increasing applications in DTC. Likewise, 18F-FDG PET is also an efficient diagnostic tool in the study of anaplastic carcinoma, poorly differentiated and other aggressive lines. It is recommended, in current clinical guidelines, as part of the initial staging in anaplastic, poorly differentiated, and invasive HCC. And it is increasingly used in other indications such as prognostic assessment, evaluation of treatment response, and even during the follow-up of high-risk patients. The use of other PET tracers, such as 68Ga-PSMA and 68Ga-DOTATATE have not clearly demonstrated their clini-cal benefit over 18F-FDG. They are usually limited to cases in which it is necessary to assess the density of somatostatin analogs and PSMA receptors prior to metabolic therapy. Conclusions: 18F-FDG PET-CT is the most effective functional diagnostic technique in the study of poorly differentiated and aggressive thyroid neoplasms, since they show little or no avidity for radioiodine and however high affinity for 18F-FDG. The role of other PET tracers for the evaluation of these tumors is promising, although it still needs studies with a larger number of patients. (AU)

PET en el diagnóstico de la patología de tiroides / PET in diagnosis of thyroid diseases

INTRODUCCIÓN Y OBJETIVO: La PET/TC es una técnica cuyas indicaciones en Oncología se encuentran en expansión y el cáncer de tiroides es una de ellas. MÉTODO: Revisión narrativa. COMENTARIOS: En el presente artículo se revisan las indicaciones establecidas hasta la fecha, así como aquellos campos en los que son necesarias investigaciones adicionales que permitan establecer la utilidad de esta técnica en los distintos tipos de patología maligna tiroidea

INTRODUCTION AND OBJECTIVE: PET/CT is a technique which oncological indications are now increasing, being thyroid cancer one of them. METHOD: narrative review. COMMENT: The present study is a review of well-known indications, as well as those fields in which more studies are needed to establish the utility of this technique in every kind of malignant thyroid pathology

Amyloid PET imaging in multiple sclerosis: an (18)F-florbetaben study.

BACKGROUND: Positron emission tomography (PET) images with amyloid tracers show normal uptake in healthy white matter, which suggests that amyloid tracers are potentially useful for studying such white matter diseases as multiple sclerosis (MS). METHODS: Twelve patients diagnosed with MS (5 with RRMS, 5 with SPMS, and 2 with PPMS) and 3 healthy controls underwent studies with MRI and (18)F-florbetaben-PET imaging. Images were preprocessed using Statistical Parametric Mapping software. We analysed (18)F-florbetaben uptake in demyelinating plaques (appearing as hyperintense lesions in FLAIR sequences), in normal-appearing white matter, and in grey matter. RESULTS: Mean standardized uptake value relative to cerebellum was higher in normally appearing white matter (NAWM) (1.51 ± 0.12) than in damaged white matter (DWM) (1.24 ± 0.12; P = .002). Mean percentage of change between NAWM and DWM was -17.56% ± 6.22%. This percentage of change correlated negatively with EDSS scores (r = -0.61, p < .05) and with age (r = -0.83, p < 0.01). Progressive forms of MS showed a more pronounced reduction of the uptake in DWM in comparison to relapsing-remitting form. CONCLUSIONS: Uptake of (18)F-florbetaben in damaged white matter is lower than that occurring in normally-appearing white matter. These findings indicate that amyloid tracers may be useful in studies of MS, although further research is needed to evaluate the utility of amyloid-PET in monitoring MS progression.