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Objetivo: Valorar la correlación existente entre los parámetros hematológicos y la captación de FDG en médula ósea (MO) y bazo en la PET. Material y métodos: 29 pacientes (pts) con linfoma de Hodgkin remitidos para un estudio inicial con FDG PET antes de comenzar el tratamiento y sin evidencia de afectación en MO, fueron incluidos en el estudio. En 18 pts sin afectación esplénica también se valoro la captación de FDG en el bazo. La captación en MO y bazo se clasificó de acuerdo a una escala visual de tres puntos, y se determinó si era homogénea o difusa. También se realizó un análisis semi-cuantitativo por medio de unos índices de captación obtenidos a través de unas regiones de interés, en médula ósea y bazo, en relación con otras en pulmón derecho e hígado. Se calcularon unos coeficientes de correlación entre la escala visual y los índices semi-cuantitativos en médula ósea y bazo, con las cifras de hemoglobina (Hb), leucocitos y plaquetas en sangre. Resultados: En 27/29 pts la captación de FDG en MO y en 18/18 pts la captación en bazo fue homogénea. Se objetivó una correlación directa entre las cifras de leucocitos y la captación de FDG en MO y bazo. La correlación era menor y además inversa con las cifras de Hb (esto es, cuanto más baja la Hb mas alta la captación en MO). Las correlaciones mas bajas se obtuvieron con la cifras de plaquetas. Conclusión: Los diferentes parámetros hematológicos pueden llegar a afectar la captación de FDG en MO y bazo. El conocimiento de esta correlación puede ayudar a la mejor interpretación de los estudios FDG PET

Objective: To assess the relationship between various hematologic parameters and bone marrow (BM) and splenic uptake of FDG in PET imaging. Material and methods: 29 patients with Hodgkin's disease (HD) referred for baseline FDG PET imaging before treatment and without evidence of bone marrow (BM) involvement were included in the study. Splenic uptake also was analyzed in 18 patients without splenic involvement. BM and splenic activity were visually graded on a 3 point scale. Activity pattern was classified as homogeneous or heterogeneous. Semi-quantitative analysis was also performed by drawing regions of interest (ROI) over the spine and spleen. ROIs also were drawn over right lung and liver. FDG uptake ratios for the spine and spleen in comparison with the lung and liver were generated. Visual scoring of marrow and splenic uptake, and the various ratios were correlated with hemoglobin (Hb), white blood cell (WBC), and platelet counts, and correlation coefficients were calculated. Results: In 27/29 patients (93 %) BM and in 18/18 patients (100 %) spleen uptake was diffuse. There was a direct correlation between BM and spleen uptake of FDG with increasing WBC, which was stronger than the inverse correlation seen with Hb (the lower the Hb the greater the uptake). Correlation with platelet counts was weaker. Conclusion: There is a correlation between hematologic parameters such as Hb, WBC and platelet counts and the uptake of FDG in BM and spleen in PET imaging. Knowledge of this correlation should help to better interpret and understand PET imaging

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Purpose: We reviewed 18F-fluorodeoxyglucose (18F-FDG) studies to determine the frequency of thymic visualization, to characterize this uptake to facilitate differentiation from disease, and to ascertain effects of therapy on visualization.Methods: Hybrid positron emission tomography images performed on 14 patients with known or suspected malignancy before therapy, and on six of the patients after treatment, were reviewed. Mediastinal uptake was characterized by location, contour and intensity.Results: Thymic uptake seen in five patients, 13-16-years-old, was characterized by an anterior midline location, regular contours, and a mean uptake ration of 2.5, and involved large glands. In five patients with mediastinal disease, 16-23-years-old, uptake was more posterior and eccentric in location with irregular borders and a mean uptake ratio of 4.3. One patient had anterior (thymic) and posterior (disease) mediastinal uptake. Three patients, 15-22-years-old, without disease and small thymus glands had no uptake. Five patients, including two with baseline uptake, showed no thymic uptake subsequently. One patient, negative initially, had thymic uptake five months after therapy.Conclusions: Thymic 18F-FDG uptake occurs in younger patients, before or after treatment, and is associated with larger glands. Its midline anterior mediastinal location and mild intensity should facilitate discrimination from disease.