The PET was schedule because of a small soft tissue nodule in lower right lung. It seems as though this could be cancerous. Is there any correlation between lung cancer and thyroid cancers?
PET would usually not have been the next step, but now that you have that info and assuming the SUV is 4.3 in the 1cm left thyroid nodule , then the next step is ultrasound and ultrasound guided FNA biopsy. PET positive nodules are more suspicious but at least half of these are benign and 4.3 is not a dramatic increase in PET uptake but definitely needs FNA biopsy to be certain. Would find a thyroid expert in your area to do ultrasound and FNA.