How do you approach rising gastrin and chromogranin levels without radiographic evidence of disease in patients with gastrinoma that has been fully resected?

We see this scenario with some frequency - rising hormone or peptide levels in functional NETs without radiographic evidence of disease. My next step would be to get the new Ga68 DOTA TATE PET/CT - essentially a new generation octreoscan with high sensitivity and specificity. These scans often pick up on disease that cannot be seen by cross-sectional imaging. If the DOTA TATE PET/CT is also negative, then I would get short interval follow-up with labs and scans, perhaps in 3 months.

Though this...