How to differentiate adenoma from bilateral hyperplasia on screening, scintigraphy and catheterization?

CT or MRI (Spiral CT with fine section is gold standard for adenoma, if >1cm mass) Iodocholesterol Scintigraphy (not used only in centers) Catheterization (reference, invasive test, post ACTH stimulation measures cortisol and aldo together, gradient >4 -->adenoma, similar gradient btw both sides -->hyperplasia, not indicated in case of adenoma >1cm and age <35 with hypokalemia