Utility of 18-fluorodeoxyglucose positron emission tomography in children with relapsed/refractory leukemia.

OBJECTIVE: Few data are available on the clinical significance of 18-fluorodeoxyglucose positron emission tomography (FDG-PET/CT) results in patients with leukemia. We investigated the utility of FDG-PET/CT at the time of relapsed/refractory disease in pediatric patients with leukemia. METHODS: Medical records of 28 children with suspected leukemia progression or recurrence during/after chemotherapy or allogeneic stem cell transplantation (allo-SCT) were retrospectively reviewed to determine the utility of FDG-PET/CT. RESULTS: Twenty-two of the 28 patients have documented abnormal imaging findings during clinical follow-up, while six had were interpreted as not demonstrating signal consistent with active leukemia. Of the 22 patients with abnormal FDG-PET/CT studies 14 were found to have FDG-PET/CT reported as consistent with active leukemia and increased leukemia blasts on bone marrow biopsy. Regarding the eight patients without positive FDG-PET/CT and proven leukemia relapse, four had discordant findings on FDG-PET/CT and biopsy, and four had FDG-PET/CT reported as infection. Mean maximum standardized uptake values (SUVmax) were significantly higher among patients whose FDG-PET/CT findings were positive for leukemia as opposed to infectious disease (p < .05). Mean SUVmax was also significantly higher among patients with multifocal lesions on FDG-PET/CT than among those with diffuse lesions (p < .05). CONCLUSIONS: The findings suggest that FDG-PET/CT may be a complementary imaging modality that could be combined with bone marrow examination to improve detection of subtle leukemic infiltration in children with suspected leukemia progression or recurrence after chemotherapy or allo-SCT.

Early post-transplantation positron emission tomography in patients with Hodgkin lymphoma is an independent prognostic factor with an impact on overall survival.

The aim of the present study was to investigate the prognostic role of pre- and/or early post-autologous stem cell transplantation (ASCT) (18)F-flourodeoxyglucose (FDG) positron emission tomography (PET) in patients with relapsed/refractory Hodgkin lymphoma. Forty-three consecutive patients were enrolled in this study. FDG-PET/CT was performed following salvage chemotherapy within 6 weeks of undergoing ASCT and at the first month after ASCT. FDG-PET positivity was found in 26 patients before ASCT and in 13 patients after ASCT. The patients who had negative PET scan before or after ASCT had significantly better outcomes in terms of overall survival (OS) and progression-free survival (PFS). Pre- and post-ASCT FDG-PET positivity was found to be independently associated with PFS while post-ASCT FDG-PET was an independent factor with an impact on OS in multivariate analysis. (18)F-flourodeoxyglucose positron emission tomography imaging may be useful in predicting prognosis after ASCT. Furthermore, effective treatment options including allogeneic stem cell transplantation might be considered in patients with positive FDG-PET scan after salvage chemotherapy and ASCT.

Unexpected Uptake by the Gallbladder in Post-Ablative I-131 Scan.

A 47-year-old woman was diagnosed as papillary thyroid carcinoma. I-131 ablation therapy was applied following total thyroidectomy, and the whole-body scan revealed a focus of increased uptake in the right upper quadrant. Lateral view images of the uptake site showed that the focus was located near the right liver lobe. The patient was referred to radiology department for correlative abdominal Computed Tomography (CT) and Ultrasonography (US) to rule out a possible liver metastasis. CT images detected a gallstone in the corresponding area, which was verified by US. These methods did not reveal any metastatic disease in the liver or in other abdominal organs. This is the first published case report documents a rare false-positive finding of I-131 scan that was associated with an asymptomatic gallstone, and emphasizes the importance of correlative imaging in gallbladder related I-131 uptake.