Quantitative study using 18F-FDG in patients with locally advanced adenocarcinoma of the esophago-gastric junction during induction chemotherapy

Objectives Early decreases of SUV >35% during induction chemotherapy have been shown to identify responders in locally advanced adenocarcinoma of the esophagogastric junction (AEG). But dynamic acquisition of such treatment has not been investigated in this tumor entity.

Methods All patients had locally advanced AEG type I or II (Siewert classification). Repetitive dynamic PET studies over 60 min took place at baseline and at day 14 after the start of inductionchemotherapy consisting of epirubicine, oxaliplatin and capecitabine . In addition to the calculation of changes of the SUV, a 2 compartment kinetic model as well as a non-compartment model using fractal dimension analysis was performed. To date, 6 out of 9 patients were included in this ongoing study.

Results Preliminary results demonstrated an overall decline of K1(median percentage (mp):-0.744) , increase of k3(mp :0.226). Patients with a deltaSUV >35% K3 showed an increase(mp :0.68), whereas patients with a decline in deltaSUV<35% (mp:-0.29) demonstrated a decreased k3. Fractal dimension (FD) presented an overall increase (mp:0.01). In responders defined by the decrease of SUV, FD demonstrated an increase (mp:0.006) and a decrease in non-responders (mp-:0.005).

Conclusions Kinetic analysis may help to increase the accuracy and to improve our understanding of the underlying mechanisms in metabolic changes during chemotherapy.