Special reports and reviews

18-fluorodeoxyglucose positron emission tomography in nonendocrine neoplastic disorders of the gastrointestinal tract

Valorar la significación y el impacto de acumulaciones de FDG en el colon en pacientes con tumores no colorrectales.

Se revisaron retrospectivamente 2.220 estudios PET-TAC realizados de manera consecutiva en el Servicio de Medicina Nuclear de nuestro hospital del 2 de diciembre de 2008 al 31 de mayo de 2010. Se incluyeron aquellos pacientes en los que se describían captaciones focales de FDG a nivel colorrectal y no explicables por la historia clínica. Se excluyeron pacientes diagnosticados previamente de carcinoma colorrectal. Cumplieron el criterio de inclusión 86 pacientes (57 hombres, media de edad de 63,4 años, rango 46-85). Se estableció como prueba de referencia la colonoscopia con toma de biopsia. Se valoró el impacto de estos hallazgos en la actitud diagnóstico-terapéutica de estos pacientes.

En 54 de los 86 pacientes se realizó correlación colonoscópica, en los 32 restantes no se había realizado dicha exploración hasta la fecha. De los 54 en los que se realizó colonoscopia se tomó biopsia en 43 lesiones. Se detectó patología colónica en 49 pacientes, con un total de 54 focos incidentales de FDG, siendo estas patologías: 10 cánceres colorrectales primarios insospechados, tres metástasis, 27 pólipos adenomatosos con diferentes grados de displasia y 14 procesos inflamatorios. En los 5 pacientes restantes la colonoscopia fue normal (9%). La PET-TAC modificó la actitud diagnóstico-terapéutica en la mayoría de pacientes (49/ 54, 91%).

Estos resultados constatan la necesidad de confirmar mediante colonoscopia y biopsia las captaciones focales colorrectales de FDG en PET-TAC. Esta estrategia permite detectar y tratar precozmente lesiones malignas y premalignas.

To assess the significance and the impact of focal FDG uptake in the colon in oncology patients without known colorectal carcinoma.

A retrospective study was undertaken on 2,220 ¹⁸F-FDG PET/CT studies carried out consecutively in the Nuclear Medicine Department in our hospital from 2 December 2008 to 31 May 2010. Inclusion criteria were patients with abnormal ¹⁸F-FDG uptake in colorectal area that could not be explained (or not previously known) by their clinical histories. Patients previously diagnosed with colorectal carcinoma were excluded. A total of 86 patients (57 male, average age 63.4, range 46-85) were finally included. Colonoscopy with biopsy was established as a reference test. The impact of these findings on the diagnostic-therapeutic management in these patients was evaluated.

A colonoscopy was performed in 54 of the 86 patients, this examination not having been done up-to-date in the remaining 32 patients. Biopsy was obtained in 43 lesions of the 54 patient in whom a colonoscopy was performed. Colon disease was detected in 49 of these 54 patients, obtaining 54 FDG incidental foci which corresponded to 10 previously unsuspected primary colorectal carcinoma, 3 metastases, 27 adenomatous polyps with different degrees of dysplasia and 14 inflammatory processes. In the remaining 5 patients, the colonoscopy was normal. PET/CT modified the diagnostic and treatment management in most of the patients (49/54, that is 91%).

These results confirm the need to determine the cause of abnormal ¹⁸F-FDG colorectal uptakes in the PET/CT studies by using colonoscopy and biopsy. This approach allows for the detection and early treatment of malignant and premalignant lesions.

Only 20% of patients who present with pancreatic cancer will be amenable to potentially curative resection. Therefore, it is necessary to reliably identify patients who might benefit from major surgical intervention by employing the appropriate staging methods. In this review, the pros and cons of each imaging technique are discussed and an algorithm for single and combined use of the different imaging modalities is proposed. To date, contrast-enhanced multi-detector row helical CT (MDR-CT) together with endoscopic ultrasound (EUS) remain the first staging methods of choice. MDR-CT has a high sensitivity for identifying vascular invasion and EUS is able to detect lesions as small as 2–3 mm. ERCP is performed mainly in patients with biliary obstruction with the option for therapeutic intervention during the same session. MRI with MR-angiography, MRCP, PET/CT and staging laparoscopy are additional modalities which might give further information in cases of equivocal findings by MDR-CT and EUS. The role of tumour markers such as CA 19-9 and CEA is reserved for monitoring and diagnosing post-surgery recurrence. Cytological or histological confirmation should usually be performed in patients that are not eligible for surgery prior to the commencement of palliative radio- or chemotherapy. In the routine clinical setting, MDR-CT and EUS play the predominant roles by providing the most cost-effective and accurate means for diagnosing and staging most cases of pancreatic cancer.