Adrenal vein sampling (AVS) is the standard method for distinguishing unilateral from bilateral sources of autonomous aldosterone production in patients with primary aldosteronism. This procedure has been performed at limited specialized centers due to its technical complexity. With recent advances in imaging technology and knowledge of adrenal vein anatomy in parallel with the development of adjunctive techniques, AVS has become easier to perform, even at nonspecialized centers. Although rare, anatomic variants of the adrenal veins can cause sampling failure or misinterpretation of the sampling results. The inferior accessory hepatic vein and the inferior emissary vein are useful anatomic landmarks for right adrenal vein cannulation, which is the most difficult and crucial step in AVS. Meticulous assessment of adrenal vein anatomy on multidetector CT images and the use of a catheter suitable for the anatomy are crucial for adrenal vein cannulation. Adjunctive techniques such as intraprocedural cortisol assay, cone-beam CT, and coaxial guidewire-catheter techniques are useful tools to confirm right adrenal vein cannulation or to troubleshoot difficult blood sampling. Interventional radiologists should be involved in interpreting the sampling results because technical factors may affect the results. In rare instances, bilateral adrenal suppression, in which aldosterone-to-cortisol ratios of both adrenal glands are lower than that of the inferior vena cava, can be encountered. Repeat sampling may be necessary in this situation. Collaboration with endocrinology and laboratory medicine services is of great importance to optimize the quality of the samples and for smooth and successful operation. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.