Initial evaluation of PET/CT imaging in patients with gastrointestinal stromal tumour

Introduction: Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumours of the gastrointestinal tract. Combined positron emission tomography using 18F-fluorodeoxyglucose (FDG) and computed tomography (PET/CT) is one of the most modern imaging methods in patients with GIST.
Aim: To perform a retrospective analysis of the clinical value of PET/CT imaging in patients with GIST after surgical treatment and/or chemotherapy.
Material and methods: PET/CT examinations were performed in 20 patients with GIST – 10 women and 10 men aged from 18 to 73 years (mean 52.1). The primary sites of the tumour were: ileum – 12, stomach – 5, mesentery – 2, duodenum – 1. The PET/CT was performed with a Biograph LSO Siemens 60-90 min after the intravenous administration of 5 MBq/kg FDG. In 2 patients PET/CT was repeated after treatment with a tyrosine kinase inhibitor.
Results: PET/CT imaging presented focal lesions with increased FDG metabolism in 9 patients. All the diagnoses were true positive. The results were true negative in the remaining 11 patients. In one patient PET/CT diagnosed tumour response to tyrosine kinase inhibitor therapy, in the other case no response.
Conclusions: PET/CT imaging may have significant clinical value in the diagnosis of postoperative recurrence of GIST after surgical treatment. This method is a useful modality to monitor treatment response to tyrosine kinase inhibitor in patients with GIST. This modality has the potential to influence clinical decision making.