Diagnosis of Pheochromocytoma Plasma free metanephrines or urinary metanephrines Chest and abdomen imaging (CT or MRI) if catecholamine screen positive Possibly nuclear imaging with I-123 MIBG (metaiodobenzylguanidine) or Gallium-68 dotatate-PET scanning Pheochromocytoma is suspected in patients with typical symptoms or particularly sudden, severe, or intermittent unexplained hypertension.