A retrospective study comparing contrast-enhanced computed tomography with 18F-FDG-PET/CT in the early follow-up of patients with retroperitoneal sarcomas.

OBJECTIVE: To compare 18-fluorine-labeled 2-deoxy-2-fluoro-D-glucose PET/computed tomography ((18)F-FDG-PET/CT) with contrast enhancement computed tomography (CECT) in the early follow-up of patients who had undergone treatment for primitive retroperitoneal sarcomas (RS).

METHODS: This is a retrospective study on 24 patients who underwent (18)F-FDG-PET/CT and CECT within 2 years after therapy for RS. (18)F-FDG-PET/CT and CECT results were compared with results of histological examination and clinical-instrumental follow-up. We calculated the sensitivity and specificity of CECT and (18)F-FDG-PET/CT for retroperitoneal recurrences and compared them with results of the McNemar test. Negative predictive values (NPVs) and positive predictive values (PPVs) were calculated and the positive percentage agreement and negative percentage agreement were evaluated.

RESULTS: The sensitivity and specificity of (18)F-FDG-PET/CT were 66.7 and 100% and those for CECT were 58.3 and 50%, respectively. For (18)F-FDG-PET/CT, PPV was 100% [95% confidence interval (CI): 67-100%] and NPV was 75% (95% CI: 58-75%); for CECT, PPV was 54% (95% CI: 33-73%) and NPV was 55% (95% CI: 30-78%). Positive percentage agreement and negative percentage agreement were, respectively, 38 and 72% for retroperitoneal lesions, 42.8 and 100% for liposarcomas, 40 and 50% for leiomyosarcomas, 14.2 and 94% for abdominal lymph nodes, and 16.6 and 100% for lung metastasis. Neither technique gave reliable results for liver metastasis.

CONCLUSION: Our data show that (18)F-FDG-PET/CT has a higher overall specificity compared with CECT in identifying areas of recurrence, demonstrating its validity for early whole-body detection of lesions. In our hands (18)F-FDG-PET/CT seems to be a good tool in the early follow-up of patients experiencing recurrence of RS.