A 44-year-old male is referred to the hypertension clinic for evaluation of blood pressure that has remained 165/100 mmHg despite being on three antihypertensive medications. Laboratory studies reveal a serum potassium of 3.1 mEq/L (Hypokalemia), a serum sodium of 146 mEq/L (Hypernatremia), and a significantly elevated Plasma Aldosterone Concentration (PAC) with a suppressed Plasma Renin Activity (PRA) (PAC/PRA ratio >30). After a salt-loading suppression test confirms the diagnosis of Primary Hyperaldosteronism, what is the most appropriate next step in the diagnostic evaluation?