Left adrenal vein CT anatomy and variants: if you know it, you report it!

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1 Left adrenal vein CT anatomy and variants: if you know it, you report it! Poster No.: C-0538 Congress: ECR 2018 Type: Educational Exhibit Authors: G. Perugin, L. Secondini, C. bergaglio, S. Barbagallo, V Prono, L. Basso, F. Rosa, I. Verardo, C. E. Neumaier ; Genova/IT, Pozzolo Formigaro/IT, Genoa/IT, Genova, It/IT Keywords: Education and training, Contrast agent-intravenous, Computer Applications-Detection, diagnosis, CT, Veins / Vena cava, Anatomy, Abdomen DOI: /ecr2018/C-0538 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 26

2 Learning objectives - Review the anatomical variants of the left adrenal vein (LAV) and its embryology. - Show CT findings of LAV anatomical variants. - Identify pitfalls in the depiction of LAV anatomy. Page 2 of 26

3 Background Laparoscopic adrenalectomy requires an accurate preoperative vascular planning in order to avoid surgical complications. Reporting LAV anatomy can help surgeons in its identification during laparoscopy. CT findings of the right adrenal vein (RAV) variants are well described in literature, while not so much has been written on the LAV CT anatomy. The knowledge of the types and frequency of adrenal vein variants would help surgeons to identify and to control the adrenal vein during the procedure. th The development of the venous system begins during the 4 week of intrauterine life. At this time, the venous blood of the embryo drains mainly through four veins, the paired anterior and posterior cardinal veins. The adrenal veins are the residuum of the caudal portion of the subcardinal veins [1,2,3]. The caudal section of the left subcardinal vein that joins the subcardinal sinus associates with the left adrenal gland and it is preserved in the adult as the LAV [4]. th The adrenal gland cortex starts its development in the 6 week of intrauterine life as a th th mesenchymal aggregation near the cranial end of the mesonephros, while in the 7-8 weeks the neural crest cells migrate in the centre of the bilayered fetal cortex and form the primordial medulla [2]. When the glands lose their connection with the coelomic mesothelium and acquire a connective tissue capsule, the maturation process begins [2]. The adrenal products from the cortex and the medulla are carried in the systemic circulation by a large central adrenomedullary vein, receiving adrenal sinusoids and departing from the adrenal hilum as adrenal vein [1,5,6]. Despite evidence suggests that there is only one large (5 mm diameter) central vein draining each gland [1,2,5,7,8], each adrenal vein has multiple accessory veins forming a network of collaterals that creates portal or caval shunts [9,10]. These veins are necessary for maintaining the blood flow to the adrenals in the event of adrenal vein obstruction [7]. Page 3 of 26

4 The LAV is longer (2 to 4 cm) than the RAV and passes downward inferomedially and posterior to the pancreatic body. In most cases, the LAV receives the left inferior phrenic vein (IPV) before draining into the left renal vein (LRV) 3-5 cm from the Inferior vena cava (IVC) [1,2,5,8,9,10,11]. Several anatomical forms and variations of the LAV are described and are more numerous than the variants of the RAV. Page 4 of 26

5 Findings and procedure details In order to avoid complications during left adrenalectomy, surgeons must be informed by radiologists about the presence of anatomic variations of the adrenal vessels and their course. We evaluated 180 consecutive abdominal CT acquired in the portal venous phase. The CT images were obtained using 64 and 128-slice CT, and were analized using MPR (MultiPlanar Reconstruction) focusing on the depiction of the course of LRV, LAV and IPV. The identification of the LAV was possible in almost all the patients (92%). We recognized the LAV as an enhancing vascular structure exiting from the left adrenal gland and draining into the LRV (Fig. 1 on page 16). Fig. 1: The LAV (red arrow) appears as an enhancing vascular structure that exits from the left adrenal gland (green arrow). References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 5 of 26

6 The limited CT spatial resolution in depicting very small vessels is ininfluent because the surgeon needs to know the anatomy of the main branches and in particular of the main adrenal vein; the other thinner vessels are cautherized during the surgical operation together with the surrounding fat and the soft tissues, without significative bleeding. The most frequent type of LAV among our patients receives the IPV before draining into the LRV, 3-5 cm from the IVC (Fig. 2 on page 16). This is the most common variation according to the literature [12] (Cesmebasi et al consider this variant as "normal"). Fig. 2: The LAV (yellow arrowhead) receives the left IPV(red arrowhead) becoming a common trunk (blue arrowhead) before draining into the LRV. The adrenal gland is pointed by a green arrowhead. References: Scuola di Specializzazione in Radiodioagnostica, Ospedale Policlinico San Martino, Genova/IT A less frequent variant is characterized by an independent drainage of the LAV and the IPV: the LAV joins the LRV alone, and also does the IPV (Fig. 3 on page 17. In the article by Loukas et al. this is the second most common variant of the left IPV [13]. Page 6 of 26

7 Fig. 3: An independent drainage of the LAV (yellow arrowhead) and the IPV (red arrowhead): the LAV joins the LRV alone, and also does the IPV. Green arrowhead: adrenal gland. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT A rare variant is a doubled LRV: in this case, the LAV receives the IPV and the common adrenal-inferior phrenic trunk drains in the anterior superior LRV (Fig. 4 on page 17). Page 7 of 26

8 Fig. 4: A doubled LRV (orange arrowhead): the LAV (yellow arrowhead) drains in the anterior superior LRV. Green arrowhead: adrenal gland. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Another case, similar to the last one, is reported in Fig. 5 on page 18, where the LAV joins a renal venous vessel forming a common trunk that drains in the LRV next to IVC confluence. Page 8 of 26

9 Fig. 5: The LAV (yellow arrowhead) joins a renal venous vessel (violet arrowhead) forming a common trunk that drains in the LRV next to IVC confluence. Green arrowhead: adrenal gland References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT In Fig. 6 on page 19, a retroaortic LRV is represented; the IPV and the LAV do not merge together in the common trunk but the IPV is received by the adrenal gland and drains in the LAV. Page 9 of 26

10 Fig. 6: The IPV (red arrowhead) and the LAV (yellow arrowhead) do not join together in the common trunk. The IPV is received by the adrenal gland (green arrowhead) and drains in the LAV. Violet arrowhead: retroaortic LRV. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT One patient presents two IPV that merge with the LAV forming a common trunk that drains in the LRV [12] (described also by Cesmebasi et al.) (Fig. 7 on page 19). Page 10 of 26

11 Fig. 7: Two IPV (red arrowhead) that merged with the LAV (yellow arrowhead) forming a common trunk (blue arrowhead) that drains in the LRV. Green arrowhead: adrenal gland. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT The last pattern, which is not included in the classification found in literature [12], is a patient with a doubled IVC: the LAV drains in the left IVC that secondly joins the right IVC, just before the intrahepatic tract (Fig. 8 on page 20). Fig. 8: A doubled IVC: the LAV (yellow arrowhead) drains in the left IVC that secondly joins the right IVC. Red arrowhead: IPV; blue arrowhead: common trunk; green arrowhead: adrenal gland. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT In case of adrenal masses the vascularity increases so more and bigger vessels can be visualized. For example, in our group of patients, we found an adrenal myelolipoma with its new blood vessels (Fig. 9 on page 21). Page 11 of 26

12 Fig. 9: A myelolipoma (green arrowhead) with its new blood vessels (yellow arrowheads). References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT In case of liver cirrhosis the portal hypertension directly causes venous dilatation; portosystemic collateral pathways develop spontaneously by the dilatation of pre-existing anastomoses between the portal and systemic venous systems. Majority of gastric varices form the gastrorenal shunt while the other form the gastrocaval shunt. The gastrorenal shunt is formed mainly by lower branch of IPV, which can open into the LRV directly (spleno-gastro-phreno-renal shunt) or via LAV. Sometimes a direct shunt can exist between the spleen and adrenal vein bypassing the gastric area (splenoadrenal-renal shunt)[14] (Fig. 10 on page 21). Page 12 of 26

13 Fig. 10: Dilatation of LAV (yellow arrowhead) and IPV (red arrowhead) in a patient with liver cirrhosis. Green arrowhead: adrenal gland. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Difficulties in the LAV identification: -First of all, we excluded from the analysis CT studies performed with less than 64-slice CT scan because of a worse recognition of the LAV; moreover 128-slice CT allows a better identification of distal vessel like IPV or other small vessels compared with 64-slice. -Another obstacle is that patients with few retroperitoneal adipose tissue have not sufficient fat surrounding the LAV that is hardly distinguishable from other structures (Fig. 11 on page 22). Page 13 of 26

14 Fig. 11: In the yellow ring, the LAV is hardly distinguishable from the other structures because of the lack of hypodense fatty tissue. References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT -In almost all patients a group of small lymph nodes (paraaortic and left inferior phrenic lymphnodes) is visible between the abdominal aorta and the adrenal gland and must be differentiated from the LAV and the IPV or their collaterals (Fig. 12 on page 22). Page 14 of 26

15 Fig. 12: In this picture a group of small lymphnodes (pink arrowhead)are hardly distinguishable from the LAV and the adrenal gland (green arrowhead). References: Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 15 of 26

16 Images for this section: Fig. 1: The LAV (red arrow) appears as an enhancing vascular structure that exits from the left adrenal gland (green arrow). Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 2: The LAV (yellow arrowhead) receives the left IPV(red arrowhead) becoming a common trunk (blue arrowhead) before draining into the LRV. The adrenal gland is pointed by a green arrowhead. Page 16 of 26

17 Scuola di Specializzazione in Radiodioagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 3: An independent drainage of the LAV (yellow arrowhead) and the IPV (red arrowhead): the LAV joins the LRV alone, and also does the IPV. Green arrowhead: adrenal gland. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 17 of 26

18 Fig. 4: A doubled LRV (orange arrowhead): the LAV (yellow arrowhead) drains in the anterior superior LRV. Green arrowhead: adrenal gland. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 18 of 26

19 Fig. 5: The LAV (yellow arrowhead) joins a renal venous vessel (violet arrowhead) forming a common trunk that drains in the LRV next to IVC confluence. Green arrowhead: adrenal gland Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 6: The IPV (red arrowhead) and the LAV (yellow arrowhead) do not join together in the common trunk. The IPV is received by the adrenal gland (green arrowhead) and drains in the LAV. Violet arrowhead: retroaortic LRV. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 19 of 26

20 Fig. 7: Two IPV (red arrowhead) that merged with the LAV (yellow arrowhead) forming a common trunk (blue arrowhead) that drains in the LRV. Green arrowhead: adrenal gland. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 8: A doubled IVC: the LAV (yellow arrowhead) drains in the left IVC that secondly joins the right IVC. Red arrowhead: IPV; blue arrowhead: common trunk; green arrowhead: adrenal gland. Page 20 of 26

21 Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 9: A myelolipoma (green arrowhead) with its new blood vessels (yellow arrowheads). Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 21 of 26

22 Fig. 10: Dilatation of LAV (yellow arrowhead) and IPV (red arrowhead) in a patient with liver cirrhosis. Green arrowhead: adrenal gland. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Fig. 11: In the yellow ring, the LAV is hardly distinguishable from the other structures because of the lack of hypodense fatty tissue. Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 22 of 26

23 Fig. 12: In this picture a group of small lymphnodes (pink arrowhead)are hardly distinguishable from the LAV and the adrenal gland (green arrowhead). Scuola di Specializzazione in Radiodiagnostica, Ospedale Policlinico San Martino, Genova/IT Page 23 of 26

24 Conclusion LAD is an easily recognizable structure and it has some anatomical variations that must be kept in mind when reporting an abdominal CT. In particular, in case of endovascular procedures or surgical adrenalectomy, the operator should be aware of anatomical LAV variants in order to correctly plan the best operating strategy. Page 24 of 26

25 References 1) Anson BJ. Morris' Human anatomy 12th Edition. New York: MCGraw-Hill ) Clemente CD. Gray's Anatomy of the Human Body. Philadelphia: Lea & Febiger ) Keith L. Moore and T.V.N. Persaud. The Developing Human: Clinically Oriented Embryology, 7th ed. Saunders: Philadelphia, ) McClure CFW, Butler EG.The development of the posterior vena cava inferior in man. Am J Anat 35, ) Hollinshead WH. Anatomy for Surgeons. Vol 2. New York: Hoeber-Harper. p ) Ross MH, Pawlina W. Histology; a Text and Atlas. 6th Ed. Philadelphia: Lippincott Williams & Wilkins. p ) Pearl M. Image-guided interventions: Abdominal aorta and the inferior vena cava. Philadelphia: Saunders. p ) Moore KL, Dalley AF, Agur AMR. Clinically oriented anatomy. 6th Ed. Philadelphia: Lippincott Williams & Wilkins. p ) Avisse C et al. Surgical anatomy and embryology of the adrenal glands. Surg Clin North Am. 80(1): ) Scholten, A., Cisco, R. M., Vriens, M. R., Shen, W. T. & Duh, Q. Y. Variant adrenal venous anatomy in 546 laparoscopic adrenalectomies. JAMA Surg 148, ) Kahn SL, Angle JF. Adrenal vein sampling. Tech Vasc Interventional Rad 13: ) Cesmebasi A. et al. A review of the anatomy and clinical significance of adrenal veins. Clin Anat 27, Page 25 of 26

26 13) Loukas M, Louis RG Jr, Hullet J, Loiacano M, Skidd P, Wagner T. An anatomical classification of the variations of the inferior phrenic vein. Surg Radiol Anat 27: ) Sharma M, Rameshbabu CS. Collateral Pathways in Portal Hypertension. Journal of Clinical and Experimental Hepatology.;2(4): Page 26 of 26