Development of a leakage monitoring system in isolated limb perfusion with portable gamma camera. / Desarrollo de un protocolo de monitorización de fuga en perfusión de miembro aislado con gammacámara portátil.

Isolated limb perfusion (ILP) is a method for treating unresectable lesions of limbs in patients with melanoma or sarcoma by using high doses of tumor necrosis factor alpha and melphalan. These high doses can result in high systemic toxicity if there is a drug leak from the isolated circulation of the limb to the systemic. This makes it imperative to monitor the leakage rate (F[%]) during the infusion, currently performed with radiotracers. The objective of this work was to develop a leakage monitoring protocol as accurate as possible to ensure safe ILP. MATERIAL AND METHOD: We built a phantom with 3compartments (body, limb and precordial area) and a high sensitivity collimator fitted to a portable gammacamera. We simulate ILP with scheduled leaks every 10minutes from 1% to 9% (theorical F[%]). We mesured F(%) using 2equation: one is the proposed in the literature and another corrected by decay of the radioisotope. We test the optimal radiopharmaceutical doses to minimize the detector dead time error and compare F(%) mesured by both equations regarding the theoretical F(%). The leakage monitoring protocol was used in 17 ILP of 16 patients and an analysis of the recorded data was performed. RESULTS: We found significant differences between F(%) mesured using the first equation and theoretical F(%), obtaining results very adjusted to the theorical after applying the decay correction. CONCLUSIONS: The decay correction of the radioisotope is a simple manner to carry out the procedure more safely, reducing the error in the calculation of F(%).

Uso de la PET-18F-FDG en pacientes con sospecha de recurrencia de cáncer diferenciado de tiroides por anticuerpos anti-tiroglobulina elevados y rastreo 131I negativo / Use of 18FFDG-PET in patients with suspicion of recurrent differentiated thyroid cancer by elevated antithyroglobulin antibodies levels and negative 131I scan

Objetivo. Valorar la utilidad de los estudios PET-18F-FDG en el seguimiento de los pacientes diagnosticados de carcinoma diferenciado de tiroides que presentan riesgo de enfermedad y niveles de tiroglobulina (Tg) no interpretables por la presencia de anticuerpos antitiroglobulina (AbTg). Material y métodos. Estudio retrospectivo de 7 mujeres con edad media de 40 años y diagnóstico histológico de cáncer diferenciado de tiroides (7 carcinomas papilares) que fueron remitidos a nuestro servicio para la realización de estudio PET-18F-FDG por sospecha de enfermedad, debido a rastreo 131I negativo y niveles de AbTg elevados, entre los años 2002 y 2007. Se les realizaron 11 exploraciones PET tras la inyección de 370-434 MBq de 18F-FDG en condiciones de normoglucemia y previa administración de relajante muscular, hidratación y furosemida. Los resultados de la PET se confirmaron por histología y/o por evolución clínico radiológica, con un período de seguimiento mínimo de 24 meses. Resultados. La prevalencia de la recurrencia de la enfermedad en la población estudiada fue del 57,14%. Todas las pacientes presentaban niveles de Tg inferiores a 3 ng/dl y AbTg superiores a 200 UI/ml. Tres pacientes presentaban antecedentes de tiroiditis. De los 11 estudios realizados la PET fue negativa en tres y positiva en 8. Se descartó la existencia de enfermedad en 3 pacientes mientras que en 4 pacientes la PET permitió localizar con éxito la existencia de recidiva. Conclusión. La PET-18F-FDG es una técnica útil para localizar enfermedad, así como para descartar la existencia de recurrencia con una elevada seguridad diagnóstica, en pacientes con antecedentes de carcinoma diferenciado de tiroides con rastreo 131I negativo, pero con elevación patológica de anticuerpos AbTg(AU)

Aim. To evaluate the utility of 18FFDG-PET for patients diagnosed of differentiated thyroid carcinoma who present risk of disease and invaluable levels of thyroglobulin (Tg) by the presence of antibodies antithyroglobulin (AbTg). Material and methods. Retrospective study of 7 women of 40 years old and histological diagnosis of differentiated thyroid cancer (7 papillary tumours) that were sent to our department for the accomplishment of18FFDG-PET study because of suspicion of disease, due to 131I negative and high levels of AbTg, between the year 2002 and 2007. 11 PET scans were obtained after the intravenous injection of 370-434 MBq of 18FFDG in normoglycemia conditions and previous administration of muscle relaxant, hydration and diuretic. The results of 18FFDG-PET scans were confirmed by pathologic examination or clinical outcome and radiographic examination for more than 24 months. Results. The prevalence of recurrence in our population was 57.14%. All patients presented levels of Tg lower than 3 ng/dl and AbTg superior to 200 UI/ml. Three patients had precedent thyroiditis. Out of 11 scans performed 3 of them were negative and 8 cases were found positive. It ruled out the existence of disease in three patients and localized the presence of recurrence in 4 patients. Conclusion. 18FFDG-PET Conclusion. CONCLUSION: 18F-FDG-PET is a useful diagnostic tool for the detection of recurrence as well as to rule out the existence of disease with a high accuracy, in patients with differentiated thyroid carcinoma with 131I whole body scan negative but with pathological elevation of antithyroglobulin antibodies(AU)

[Use of 18F FDG-PET in patients with suspicion of recurrent differentiated thyroid cancer by elevated antithyroglobulin antibodies levels and negative ¹³¹I scan]. / Uso de la PET-18F-FDG en pacientes con sospecha de recurrencia de cáncer diferenciado de tiroides por anticuerpos anti-tiroglobulina elevados y rastreo ¹³¹I negativo.

AIM: To evaluate the utility of (18F)FDG-PET for patients diagnosed of differentiated thyroid carcinoma who present risk of disease and invaluable levels of thyroglobulin (Tg) by the presence of antibodies antithyroglobulin (AbTg). MATERIAL AND METHODS: Retrospective study of 7 women of 40 years old and histological diagnosis of differentiated thyroid cancer (7 papillary tumours) that were sent to our department for the accomplishment of(18F)FDG-PET study because of suspicion of disease, due to ¹³¹I negative and high levels of AbTg, between the year 2002 and 2007. 11 PET scans were obtained after the intravenous injection of 370-434 MBq of (18F)FDG in normoglycemia conditions and previous administration of muscle relaxant, hydration and diuretic. The results of (18F)FDG-PET scans were confirmed by pathologic examination or clinical outcome and radiographic examination for more than 24 months. RESULTS: The prevalence of recurrence in our population was 57.14%. All patients presented levels of Tg lower than 3 ng/dl and AbTg superior to 200 UI/ml. Three patients had precedent thyroiditis. Out of 11 scans performed 3 of them were negative and 8 cases were found positive. It ruled out the existence of disease in three patients and localized the presence of recurrence in 4 patients. CONCLUSION: (18F)FDG-PET CONCLUSION: 18F-FDG-PET is a useful diagnostic tool for the detection of recurrence as well as to rule out the existence of disease with a high accuracy, in patients with differentiated thyroid carcinoma with ¹³¹I whole body scan negative but with pathological elevation of antithyroglobulin antibodies.