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)

18F-FDG PET/CT in ovarian cancer recurrence: Clinical impact, correlation with ceCT and CA-125, and prognostic value.

AIM: To evaluate 18F-FDG-PET/CT for suspected ovarian cancer relapse with negative/inconclusive conventional imaging, or restaging potentially resectable ovarian cancer relapse. MATERIAL AND METHODS: Thirty-six cases and 140 locations were studied. PET/CT, ceCT and serum CA-125 was conducted in all cases. Nineteen cases were requested for restaging, 17 for suspected relapse. We compared ceCT and PET/CT, assessed by histopathology or radiological follow-up, calculating sensitivity (S) and positive predictive value (PPV) by cases and lesions. We evaluated the correlation between size, number, uptake of the lesions and CA-125. We conducted survival analysis, using ROC curves to calculate the optimal cut-off of SUVmax for survival prediction. We checked whether PET/CT modify the therapeutic attitude vs. conventional imaging. RESULTS: PET/CT and ceCT were concordant in 12 cases: 11 positives (30 lesions), all confirmed. There was 1 FN. In the 24 non-concordant, PET/CT was positive in 19 (97 lesions); ceCT in 21 (59 lesions); 54% of the lesions were concordant. Overall, PET/CT detected 127 lesions, with S=97% and PPV=100%. ceCT detected 89 lesions, with S=61% and PPV=90%. No significant correlation was found between CA-125 and the other parameters. PET/CT detected 10 positive cases, with normal CA-125. PET/CT modified therapeutic management in 15 cases. Significant differences were found in survival with SUVmax=11.8 CONCLUSIONS: PET/CT plays an important role in ovarian cancer relapse, with sensitivity and PPV higher than ceCT, modified therapeutic management in up to 42% of cases, and could be a valuable tool for predicting survival.

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

Leptomeningeal carcinomatosis as only pathological finding at FDG-PET/CT in case of tumor marker elevation in breast cancer.

Leptomeningeal carcinomatosis is an infrequent disease and although its treatment is palliative, earlier diagnosis will lead to prolonged survival and improve functional outcome. Whole-body FDG-PET allows the entire spinal cord to be examined noninvasively, so close attention should be paid to the spinal canal, since these lesions can easily be mistaken for physiologic uptake, sometimes there is no clinical suspicion and may occur without concurrent active cancer. We present a female patient with a history of carcinoma of the breast, who presented an elevation of serum tumor marker CA 15-3. An FDG-PET/CT study only revealed multiple abnormal uptake at the vertebral foramen at thoracic and lumbosacral regions suggesting leptomeningeal metastases that were confirmed by MRI and cerebrospinal fluid cytology.

Estimation of the total effective dose from low-dose CT scans and radiopharmaceutical administrations delivered to patients undergoing SPECT/CT explorations.

UNLABELLED: Hybrid imaging, such as SPECT/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. OBJECTIVES: The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). METHODS: 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. RESULTS: The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85% with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. CONCLUSIONS: The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose.