What is the recommendation for persistent PET uptake and elevated catecholamines at 4 months following subtotal resection and adjuvant radiation for a thoracic secretory paraganglioma?  

A young patient presented with a large rt apical lung secretory paraganglioma invading pleura and the adjacent vertebral body.  Genetic testing was nl.  He underwent subtotal resection of the lesion, leaving the vertebral portion.  He received adjuvant radiation to 50 Gy.  At 4 months, his catecholamines are improved but still elevated.  FDG-PET shows persistent uptake in the vertebral body, without progression.  What should be next steps - continued surveillance or some intervention?