Anatomical Variations of the Left Adrenal Vein Encountered During Venous Sampling.

PURPOSE To identify the anatomical variations in the left adrenal vein (LAV) and to evaluate the role of preprocedural contrast-enhanced CT (CECT) planning. MATERIALS AND METHODS The length of the left adrenal central vein (LACV), the vessel that receives blood from all tributaries of the left adrenal gland, was measured on venograms of patients who had undergone adrenal venous sampling (AVS) for the diagnosis of primary aldosteronism (PA) between October 2017 and December 2019. The anatomical variants were described and classified. CECT was used to evaluate the detection rate of (1) confluence of the left inferior phrenic vein (LIPV) and the LAV and (2) the last tributary that flows into the LAV. RESULTS In total, 311 patients (143 men, 168 women; mean age: 49.3 ± 11.0 years) were enrolled. Of them, 9 patients (2.9%) had anatomical variants lacking LACV. In patients with LACV (n = 302), the venographic LACV length was 9.0 ± 3.9 mm (<1 mm in 9 patients). The detection rate of the confluence of the LIPV and the LAV by CECT was high (96.2%), while that of the last tributary that flows into the LAV was low (0.8%). In 4 of the 18 patients with short or absent LACV, the variant was visualized on CECT. CONCLUSIONS In some patients LACV is absent or short as an anatomical variation. Understanding the venographic anatomical variations can help avoid misleading results due to the sampling site in AVS. For some subtypes, CECT may also help in planning the AVS procedure.