Hypertension and an adrenal mass in a 31-year-old

31-year-old man with paroxysmal headaches, sweating and hypertension (170/105 mmHg). Plasma normetanephrine 4.9 nmol/L (upper reference limit 1.0), metanephrine normal, 3-methoxytyramine 0.9 nmol/L (upper reference limit 0.1). CT shows a 5.5 cm heterogeneous left adrenal mass. His father died in his forties of a 'paraganglioma'. Germline genetic testing has been sent. The endocrinologist asks for functional imaging before surgery.