Utility of low dose (18)F-FDG PET-CT in patients with suspected colorectal carcinoma recurrence in conventional diagnostic methods.

OBJECTIVE: To evaluate the efficacy of (18)F-FDG PET-CT in the diagnosis of recurrence of colorectal cancer (CRC) in patients with elevated values of carcinoembryonic antigen (CEA) and/or signs of recurrence in the multidetector CT (MDCT), and to demonstrate that good results can be obtained applying the ALARA principles. MATERIAL AND METHODS: A retrospective study of 54 patients with suspected CRC, who underwent an (18)F-FDG PET-CT, administering a mean dose of 222 MBq (6 mCi) of (18)F-FDG, from 07/2007 to 01/2011 was carried out. Seven patients were excluded, thus studying 47 (27 males, 20 females, mean age 63 years). Recurrence was confirmed by histopathology study in 14 cases and by clinical evolution in 33. The patients were divided into 4 groups. A: patients with elevation of CEA and suspected recurrence in the MDCT. B: elevation of CEA, without suspicious lesions in the MDCT. C: normal levels of CEA and positive MDCT. D: normal levels of CEA and uncertain MDCT. RESULTS: We found sensitivity, specificity, PPV, NPV and overall accuracy of 91%, 69%, 89%, 75% and 85% respectively. For group A, we found 100% sensitivity, in group B, 75% sensitivity with 100% specificity%, for C, sensitivity was 89% with 71% specificity. Finally, in group D, sensitivity was 100% and specificity 60%, respectively. CONCLUSION: Applying a low dose, the (18)F-FDG PET-CT has high diagnostic performance in patients with suspicion of CRC, approaching in a higher grade the ALARA criteria.

Utilidad de la PET-TC con baja dosis de 18F-FDG en pacientes con sospecha de recurrencia de carcinoma colorrectal en métodos diagnósticos convencionales / Utility of low dose 18F-FDG PET-CT in patients with suspected colorectal carcinoma recurrence in conventional diagnostic methods

Propósito. Evaluar la eficacia de la 18F-FDG PET-TC en el diagnóstico de la recurrencia del carcinoma colorrectal (RCCR), en pacientes con valores de CEA elevados y/o signos de recurrencia en la TC multidetector (TCMD), así como demostrar que se pueden obtener buenos resultados aplicando los principios ALARA. Materiales y métodos. Estudio retrospectivo de 54 pacientes con sospecha de RCCR, a los cuales se les realizó una 18F-FDG PET-TC, administrando una dosis media de 222 MBq (6 mCi) de 18F-FDG, desde 07/2007 hasta 01/2011. Excluimos 7 pacientes, estudiando a 47 (27 varones, 20 mujeres, edad media 63 años). La recurrencia se confirmó por histopatología en 14 casos y por evolución clínica en 33. Los pacientes se dividieron en 4 grupos. A: pacientes con elevación del CEA y sospecha de recidiva en la TCMD. B: elevación del CEA, sin lesiones sospechosas en la TCMD. C: niveles de CEA normales y la TCMD positiva. D: niveles de CEA normales y la TCMD dudosa. Resultados. : Encontramos una sensibilidad, especificidad, VPP, VPN y exactitud global de 91, 69, 89, 75 y 85, respectivamente. Para el grupo A encontramos una sensibilidad del 100%, en el B una sensibilidad del 75% y especificidad del 100%, para el C una sensibilidad del 89% y especificidad del 71%, finalmente para el D una sensibilidad y especificidad del 100 y 60%, respectivamente. Conclusión. Aplicando una baja dosis, la 18F-FDG PET-TC tiene un alto rendimiento diagnóstico en pacientes con sospecha de RCCR, acercándose en mayor grado a los criterios ALARA(AU)

Objective. To evaluate the efficacy of 18F-FDG PET-CT in the diagnosis of recurrence of colorectal cancer (CRC) in patients with elevated values of carcinoembryonic antigen (CEA) and/or signs of recurrence in the multidetector CT (MDCT), and to demonstrate that good results can be obtained applying the ALARA principles. Material and methods. A retrospective study of 54 patients with suspected CRC, who underwent an 18F-FDG PET-CT, administering a mean dose of 222 MBq (6 mCi) of 18F-FDG, from 07/2007 to 01/2011 was carried out. Seven patients were excluded, thus studying 47 (27 males, 20 females, mean age 63 years). Recurrence was confirmed by histopathology study in 14 cases and by clinical evolution in 33. The patients were divided into 4 groups. A: patients with elevation of CEA and suspected recurrence in the MDCT. B: elevation of CEA, without suspicious lesions in the MDCT. C: normal levels of CEA and positive MDCT. D: normal levels of CEA and uncertain MDCT. Results. We found sensitivity, specificity, PPV, NPV and overall accuracy of 91%, 69%, 89%, 75% and 85% respectively. For group A, we found 100% sensitivity, in group B, 75% sensitivity with 100% specificity%, for C, sensitivity was 89% with 71% specificity. Finally, in group D, sensitivity was 100% and specificity 60%, respectively. Conclusion. Applying a low dose, the 18F-FDG PET-CT has high diagnostic performance in patients with suspicion of CRC, approaching in a higher grade the ALARA criteria(AU)

Foco pulmonar facticio con 18F-FDG: posible error en la interpretación de la PET-CT / Lung hot spot as pitfall in PET-CT interpretation: focal lung uptake of 18F-fluorodeoxyglucose

Aportamos dos casos de pacientes oncológicos en seguimiento rutinario con este tipo de artefacto, sin correlato morfológico en la TAC. Se procedió a la repetición del estudio en uno de ellos, lo que permitió comprobar una normalización de dicha hipercaptación, orientando a un posible artefacto. La PET-TAC con FDG se ha convertido en una herramienta imprescindible en el manejo del paciente oncológico. La distribución normal de la FDG y los posibles artefactos (pitfalls), incluidos aquéllos derivados de la corrección de atenuación basada en la TAC, han sido descritos en diversas revisiones. Sin embargo, sólo recientemente se ha publicado algún caso de falso positivo en forma de captación focal pulmonar de FDG(AU)

18F-FDG PET-CT has become an essential tool in oncology patient management. The normal distribution of the FDG and the possible artifacts (pitfalls), including those from CT-based attenuation correction, have already been described in several reviews. However, only a few cases of FDG focal lung uptake have been reported recently. We present two cases of oncology patients during a routine follow-up with this type of pitfall, without morphological correlation in the CT scan. We repeated the study in one of them, which made it possible to verify normalization of the hyperuptake, orienting us towards a possible pitfall(AU)

[Lung hot spot as pitfall in PET-CT interpretation: focal lung uptake of 18F-fluorodeoxyglucose]. / Foco pulmonar facticio con (18)F-FDG: posible error en la interpretación de la PET-CT.

(18)F-FDG PET-CT has become an essential tool in oncology patient management. The normal distribution of the FDG and the possible artifacts (pitfalls), including those from CT-based attenuation correction, have already been described in several reviews. However, only a few cases of FDG focal lung uptake have been reported recently. We present two cases of oncology patients during a routine follow-up with this type of pitfall, without morphological correlation in the CT scan. We repeated the study in one of them, which made it possible to verify normalization of the hyperuptake, orienting us towards a possible pitfall.

Gammagrafía abdominal con leucocitos marcados en la isquemia intestinal / Abdominal scintigraphy using labelled leukocytes in intestinal ischaemia

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