Morphological Analysis of Gastrorenal Shunts Using Three-dimensional Computed Tomography-Portography: A Comparison with Intraoperative Venography During Balloon-occluded Retrograde Transvenous Obliteration

Morphological Analysis of Gastrorenal Shunts Using Three-dimensional Computed Tomography-Portography: A Comparison with Intraoperative Venography During Balloon-occluded Retrograde Transvenous Obliteration | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Morphological Analysis of Gastrorenal Shunts Using Three-dimensional Computed Tomography-Portography: A Comparison with Intraoperative Venography During Balloon-occluded Retrograde Transvenous Obliteration Yoshimi Fujii, Masato Tanikake, Yurie Nishimura, Kazuma Yasui This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6424084/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose Balloon-occluded retrograde transvenous obliteration (BRTO) is an endovascular treatment for gastric varices. Successful BRTO requires deep catheterization of the gastrorenal shunt which constitutes the main efferent pathway of the varices. However, the complex anatomy of the shunt can complicate catheter manipulation. This study aimed to clarify the morphological features of gastrorenal shunts relevant to BRTO using three-dimensional computed tomography (3DCT)-portography and to evaluate its concordance with intraoperative venography. Methods Patients who underwent BRTO between January 2017 and October 2024 were included. Preoperative dynamic contrast-enhanced CT was used to reconstruct 3DCT-portography images. The morphological evaluation focused on stenosis and angulation of the shunt. Measurements compared between 3DCT-portography and intraoperative venography included the distance from the left renal vein to the stenosis, vertebral level of the stenosis, stenotic diameter, common trunk diameter with the left adrenal vein, and stenosis rate. Results Nineteen patients were included. All showed a stenosis just above the common trunk with the left adrenal vein (17 ± 4.7 mm from the left renal vein). A marked dorsal angulation (62.9 ± 18.4°) was observed cranial to the stenosis. No significant differences were found between the two modalities in most measurements, indicating high concordance. However, a significant difference was noted at the vertebral level (p = 0.0022), with 3DCT-portography showing a lower position. Conclusion : Consistent stenosis was observed just above the common trunk, with a dorsal angulation cranial to it. The gastrorenal shunt anatomy was effectively visualized using 3DCT-portography, which showed good correlation with the intraoperative venography findings. Gastrorenal shunt Gastric varices Balloon-occluded retrograde transvenous obliteration (BRTO) Portal hypertension Three-dimensional computed tomography (3DCT) Figures Figure 1 Figure 2 Figure 3 Introduction Gastric varices are serious complications that occur in approximately 20% of the patients with portal hypertension [1]. Although less likely to rupture than esophageal varices, rupture of gastric varices can lead to massive bleeding and remains associated with a high mortality rate of 15–25%, even in recent years [2–4]. Balloon-occluded retrograde transvenous obliteration (BRTO) is an endovascular treatment for gastric varices. In BRTO, the gastrorenal shunt, which serves as the efferent vein of the varices, is occluded with a balloon, and a sclerosant is injected into the varices [5–7]. The recurrence rate after BRTO is less than 10% [8–10], and the procedure has become widely accepted worldwide as an effective treatment for gastric varices [11–13]. To ensure a successful BRTO, the sclerosant must be injected extensively from the efferent vein into the varices and upstream of the afferent veins. A thorough understanding of the anatomy and hemodynamics of gastric varices is essential for effective treatment. Gastric varices receive blood from the left gastric, posterior gastric, and short gastric veins, and drain into the left inferior phrenic, paraesophageal, azygos, and cardiophrenic veins. Among these, the left inferior phrenic vein plays a central role as an efferent pathway [14–16]. The left inferior phrenic vein originates near the diaphragm, joins the gastric varices at the serosa-free area of the gastric fundus, and divides into transverse and descending branches that return to the systemic circulation. The transverse branch runs horizontally below the diaphragm and drains directly into the inferior vena cava, whereas the descending branch courses caudally, joins the left adrenal vein, and flows into the left renal vein [16]. This descending pathway is dilated and functions as a gastrorenal shunt, serving as a major portosystemic collateral in portal hypertension [14–16]. The gastrorenal shunt descends from the perigastric area into the retroperitoneum with marked tortuosity. Multiple stenoses and angulations exist along its course, and several fine tributaries join, giving rise to the complex shunt morphology. In BRTO, the catheter must be advanced retrogradely into the appropriate site within the shunt; however, owing to this anatomical complexity, catheter manipulation is often technically challenging. Although several anatomical studies have examined the left inferior phrenic vein [16–20], few have focused on the morphology of the gastrorenal shunt itself [21]. This study aimed to characterize the anatomical features of the shunt outlet relevant to catheter manipulation in BRTO using three-dimensional CT (3DCT)-portography and evaluate its concordance with intraoperative venography findings. Methods This retrospective study was approved by the Ethics Committee of Fujisawa City Hospital (approval no. F2024027) and conducted in accordance with the Ethical Guidelines for Life Science and Medical Research Involving Human Subjects issued by the Ministry of Health, Labour and Welfare; the Ministry of Education, Culture, Sports, Science and Technology; and the Ministry of Economy, Trade and Industry of Japan. Because this study involved the retrospective use of medical records and imaging data, the requirement for written informed consent was waived and consent was obtained via an opt-out process. Patients A database of patients who underwent BRTO for gastric varices at our institution between February 2017 and October 2024 was retrospectively reviewed. Patients were excluded if dynamic contrast-enhanced computed tomography (CT) was not performed preoperatively, BRTO was performed via the transverse branch of the left inferior phrenic vein, or intraoperative venography was performed using carbon dioxide. Clinical background, endoscopic and imaging findings, and procedural details were obtained from electronic medical records. Preprocedural Contrast-Enhanced CT A bolus injection of an iodinated contrast agent (460 mgI/kg) was administered via a peripheral vein at 3.0–4.0 mL/s. The arterial, portal venous, and delayed phases were acquired at 40, 60, and 120 s after injection, respectively. All the phases were obtained at 100 keV. Using dedicated image processing software (ZAIO Station System, Amin), 3DCT-portography of the gastric varices, gastrorenal shunt, left renal vein, and vertebral column, was reconstructed. Intraoperative Gastrorenal Shunt Venography During BRTO, an 8-Fr guiding sheath was inserted via the right femoral or internal jugular vein and advanced to the outlet of the gastrorenal shunt through the left renal vein. A 5.2-Fr balloon catheter was inserted through the sheath and positioned near the shunt outlet. Manual injection of 5–7 mL iodinated contrast medium was administered. The balloon catheter was advanced deeper into the shunt, and venography was performed under balloon occlusion. Once adequate opacification of the varices and afferent veins was confirmed, the sclerosant was injected from that position. The balloon catheter was left in place overnight and was removed the following day. Measurements 3DCT-portography was used to assessed the presence of stenosis and angulation near the shunt outlet and the following parameters were measured: Distance from the left renal vein to the stenosis (mm), vertebral level Stenotic diameter (A) (mm) Diameter of the common trunk with the left adrenal vein (B) (mm) Stenosis rate: (1 − A/B) × 100 (C) (%) Angle of the most prominent angulation (°) Distance from the stenosis to the site of greatest angulation (mm) Vertebral levels were divided into the upper, middle, and lower thirds, and the intervertebral spaces were considered at one level. For statistical analysis, each level was assigned a numerical value at regular intervals (e.g., upper L2 = 0, L1/2 = 0.5, lower L1 = 1, middle L1 = 1.5, and upper L1 = 2), extending from L2 to T10. The following parameters were also measured using intraoperative gastrorenal shunt venography and compared with those obtained using 3DCT-portography: Distance from the left renal vein to the stenosis (mm), vertebral level Stenotic diameter (a) (mm) Diameter of the common trunk (b) (mm) Stenosis rate: (1 − a/b) × 100 (c) (%) Statistical Analysis Statistical tests were performed to compare the measurements between 3DCT-portography and gastrorenal shunt venography. Paired t-tests were used for normally distributed data and the Wilcoxon signed-rank test was used for non-normally distributed data. Bland‒Altman analysis was conducted to assess the agreement between the two modalities and to evaluate fixed and proportional biases. All analyses were performed using the Modified R Commander (version 4.4.2), with a p-value < 0.05 considered statistically significant. Results During the study period, 22 BRTO procedures were performed on 20 patients. Of these, three cases were excluded, and a total of 19 cases (14 men, 5 women; mean age, 66.1 ± 9.6 years) were included in the final analysis. The patient characteristics are summarized in Table 1. On 3DCT-portography, multiple stenoses were identified within the gastrorenal shunt. In all cases, a stenosis was observed just above the common trunk with the left adrenal vein, located 17 ± 4.7 mm from the left renal vein. Additionally, a marked dorsal angulation (62.9 ± 18.4°) was noted 20.1 ± 10.3 mm cranial to the stenosis. Detailed results are presented in Table 2 and Figure 1. Comparison between 3DCT-portography and gastrorenal shunt venography revealed no statistically significant differences in the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, or stenosis rate. However, a significant difference was observed in the vertebral stenosis level (p = 0.0022) (Figure2). Bland–Altman analysis showed no fixed or proportional bias in the measurements of the distance to the stenosis, stenotic diameter, common trunk diameter, or stenosis rate between 3DCT-portography and venography, indicating a high level of agreement between the two modalities. In contrast, a significant fixed bias was identified at the vertebral level of the stenosis (p = 0.002153), with 3DCT-portography showing a lower position by 0.79 vertebral levels (95% confidence interval: –1.25 to –0.33) (Figure 3). Table 1 Patient characteristics Characteristics n=18 Age (mean±SD, years) 66.1±9.6 Sex（male/female） 14/5 BMI（mean±SD, kg/m 2 ） 27.1±4.2 Disease origin（virus/alcohol/NASH/other） 5/7/3/4 Child–Pugh Class（A/B/C） 16/2/1 Child–Pugh score 5.8±1.4 Ascites（no/yes） 17/2 HCC（no/yes） 16/3 Esophageal varices（no/yes） 10/9 Hepatic encephalopathy 19/0 Portal vein thrombosis（no/yes） 18/1 Endoscopic evaluation of gastric varices Location; Lg-f/Lg-c/Lg-cf 11/2/6 Form; F1/F2/F3 1/13/5 Color; Cw/Cb 7/12 Red-Color sign (no/yes) 17/2 Mucosal findings (no/yes) 15/4 Bleeding findings (no/yes) 18/1 SD, standard deviation; NASH, non-alcoholic steatohepatitis; HCC, hepatocellular carcinoma Table 2 Comparison of Measurements Between 3DCT-Portography and GRS Venography Parameter 3DCT-Portography GRS Venography p-value Distance from LRV to Stenosis (mm) 17.0±4.7 17.4±5.2 0.303 Stenotic Diameter (mm) 5.6±1.7 5.1±1.6 0.056 Common Trunk Diameter (mm) 9.6±2.9 9.1±2.9 0.166 Stenosis Rate (%) 40.9±13.9 43.0±11.5 0.399 Vertebral Level of Stenosis 1.8±1.1 2.6±0.9 0.0022 upper L1 to mid L2 lower T12 to upper L1 3DCT, three-dimensional computed tomography; GRS, gastrorenal shunt; LRV, left renal vein Discussion This study evaluated the morphology of the gastrorenal shunt outlet relevant to BRTO procedures using preoperative 3DCT-portography. In all cases, stenosis was observed just above the common trunk with the left adrenal vein and a marked dorsal angulation was present cranial to this site. The morphological measurements obtained from 3DCT-portography, including the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, and stenosis rate, showed no significant differences compared to those obtained by intraoperative venography, demonstrating high concordance between the two modalities. Since the 2000s, several studies have described the use of CT to visualize the vascular anatomy of gastric varices [22–24]. The introduction of multislice CT-enabled high-resolution imaging and facilitated the reconstruction of vascular anatomy using multi planar reconstruction (MPR) and volume rendering (VR) techniques. With further advances in CT hardware and software, it is now possible to clearly depict the complex vascular anatomy of gastric varices. In this study, 3DCT-portography accurately reproduced the structure of the gastrorenal shunt and corresponded well with the intraoperative venography findings. This modality is expected to be useful for preoperative catheter simulation and device selection because it provides detailed anatomical information. However, a significant difference was observed in the vertebral level of the stenosis, with 3DCT-portography showing a lower position by a mean of 0.79 levels. This discrepancy is likely because of the differences in the respiratory phase during image acquisition; dynamic contrast-enhanced CT was performed during inspiration, whereas venography was performed during expiration. Meanwhile, the distance from the left renal vein to the stenosis showed no significant difference between the two modalities. Therefore, the position of the stenosis on 3DCT-portography should be evaluated based not only on the vertebral level but also on its distance from the left renal vein. The use of 3DCT-portography is already considered essential for preoperative imaging prior to BRTO. Recently, fusion of preoperative 3DCT-portography with intraoperative fluoroscopy has been attempted to enable more effective and less invasive procedures [21]. Using 3DCT-portography as a roadmap may help reduce the number of intraoperative imaging runs, as well as the total volume of contrast medium and fluoroscopy time. In a comprehensive review of BRTO procedures, Wael et al. were the first to address the morphology of a gastrorenal shunt and its influence on catheter manipulation [15,25]. They noted that web-like narrowing is often present at the junction of the gastrorenal shunt-proper and the left adrenal vein, which may impede the passage of a catheter or guidewire. Thus, attention to the branching angle of gastrorenal shunt-proper is essential for safe catheter navigation. In our study, stenosis was observed just above the common trunk in all patients, and marked dorsal angulation was noted cranially. This angulation likely corresponded to the transition zone between the intraperitoneal and retroperitoneal portions of the shunt. During retrograde catheterization of the shunt, not only stenosis but also angulation can hinder device advancement. Unintended catheter manipulation may increase the risk of vascular injury; therefore, surgeons should carefully consider the anatomy, from the stenosis to the point of angulation. To date, no histopathological studies have investigated the nature of the stenosis observed within gastrorenal shunts. Araki et al. analyzed venography of the left inferior phrenic vein during adrenal vein sampling and identified a ‘valvular structure’ at the caudal end of the vein near its junction with the left adrenal vein [20]. This structure was located 16.4 ± 4.7 mm from the left renal vein, corresponding closely with the site of stenosis observed in our study (17.0 ± 4.7 mm). As Araki et al. studied patients without portal hypertension, our findings suggest that stenosis just above the common trunk may be a congenital feature independent of portal hypertension. If, as Araki et al. suggest, this represents a downward-facing valve, it could explain the difficulty in advancing catheters and guidewires through this site despite the relatively mild degree of stenosis (mean stenosis rate: 40.9 ± 13.9%). Further investigations using modalities, such as intravascular or endoscopic ultrasound may help clarify the nature of this structure. This study had some limitations. First, the sample size was small. Second, respiratory motion may have influenced the measurements. As mentioned earlier, CT was performed during inspiration, whereas venography was performed during expiration, which may have contributed to the significant difference in the vertebral level. Moreover, the increased venous return during inspiration and possible Valsalva effect may have led to an overestimation of the venous diameter on CT. Third, intraoperative venography was manually performed, and variations in the contrast volume or injection rate may have affected the image quality and measurements. In conclusion, stenosis was consistently identified just above the common trunk of the left adrenal vein and marked dorsal angulation was observed cranial to the stenosis. Preoperative 3DCT-portography accurately depicted the structure of the gastrorenal shunt and corresponded well with intraoperative venography. The anatomical features revealed in this study may contribute to safer and more effective endovascular treatment for gastric varices. Abbreviations BRTO, Balloon-occluded retrograde transvenous obliteration 3DCT, Three-dimensional computed tomography SD, Standard deviation NASH, Non-alcoholic steatohepatitis HCC, Hepatocellular carcinoma GRS, Gastrorenal shunt Declarations Author Contribution Y. F. conceived and designed the study. Y.F., M.T., Y.N., and K.Y. were involved in data acquisition and curation. Y.F. performed the statistical analysis and drafted and revised the manuscript. All authors reviewed and approved the final version of the manuscript. Data Availability The imaging data analysed during this study are not publicly available due to patient privacy concerns but are available from the corresponding author upon reasonable request with appropriate ethical approvals. References Garcia-Tsao G, Abraldes JG, Berzigotti A, Bosch J (2017) Portal hypertensive bleeding in cirrhosis: Risk stratification, diagnosis, and management: 2016 practice guidance by the American Association for the study of liver diseases. 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Abdom Imaging 35:1–7. https://doi.org/10.1007/s00261-009-9506-y Kiyosue H, Ibukuro K, Maruno M, Tanoue S, Hongo N, Mori H (2013) Multidetector CT anatomy of drainage routes of gastric varices: a pictorial review. Radiographics 33:87–100. https://doi.org/10.1148/rg.331125037 Saad WEA, Kitanosono T, Koizumi J, Hirota S (2013) The conventional balloon-occluded retrograde transvenous obliteration procedure: indications, contraindications, and technical applications. Tech Vasc Interv Radiol 16:101–151. https://doi.org/10.1053/j.tvir.2013.02.003 Additional Declarations No competing interests reported. Supplementary Files Graphicalabstract.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6424084","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":456039362,"identity":"51bfa6b5-d57a-430e-9d8e-9f9f6862276d","order_by":0,"name":"Yoshimi Fujii","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIiWNgGAWjYBAC9gaGhAMJQAYbA2PjAyDNw0dIC88BhJZmA5AAGxFa4IBNAkwS1CKR8PDAwzYbez6xw22VX3PsZNgYmB8+uoFfS8KBxLa0xDbpxLbbstuSgQ5jMzbOwaPFHqLlcAIbSIvkNmagFh42aXxaoLYctgdpKZbcVk+8FkaQwxg/bjtMhBaeB8BAPgf2S7M047bjPGzMBPzCw56T/PFHmY29/Oz0hx9/bqu252dvfvgYnxagpgQGRmhcMPOASbzKQYD9AAPDHwiT8QdB1aNgFIyCUTASAQCiWEcchCn4zQAAAABJRU5ErkJggg==","orcid":"","institution":"Fujisawa City Hospital","correspondingAuthor":true,"prefix":"","firstName":"Yoshimi","middleName":"","lastName":"Fujii","suffix":""},{"id":456039363,"identity":"c15f29b6-b815-4360-8322-f745c6e8eb10","order_by":1,"name":"Masato Tanikake","email":"","orcid":"","institution":"Fujisawa City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Masato","middleName":"","lastName":"Tanikake","suffix":""},{"id":456039364,"identity":"6055b024-6ab8-4b4a-ab95-c2c118d7a3a1","order_by":2,"name":"Yurie Nishimura","email":"","orcid":"","institution":"Fujisawa City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yurie","middleName":"","lastName":"Nishimura","suffix":""},{"id":456039365,"identity":"0c4f0b86-4aa2-4ef4-9b78-266b1a66bb6d","order_by":3,"name":"Kazuma Yasui","email":"","orcid":"","institution":"Fujisawa City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kazuma","middleName":"","lastName":"Yasui","suffix":""}],"badges":[],"createdAt":"2025-04-11 02:38:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6424084/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6424084/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87242091,"identity":"e559111c-7cc9-435c-9f40-86dc1172d3c2","added_by":"auto","created_at":"2025-07-22 01:41:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":609158,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e 3DCT-portography clearly depicts the entire gastric varices, including the afferent and efferent pathways. \u003cstrong\u003eb\u003c/strong\u003e Stenosis is seen at the confluence with the left adrenal vein, 17±4.7 mm from the left renal vein. \u003cstrong\u003ec\u003c/strong\u003e Marked dorsal angulation is seen 20±10.3 mm cranial to the stenosis (62.9±18.4).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6424084/v1/665b48dfed9adb3ed12aa97c.png"},{"id":87242090,"identity":"0c9efa40-2eb4-43a2-9a88-cc4647734ed7","added_by":"auto","created_at":"2025-07-22 01:41:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":122183,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of measurements between 3DCT-portography and GRS venography.\u003cstrong\u003e a b c d\u003c/strong\u003e No significant differences are observed in the measurements of the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, or stenosis rate. \u003cstrong\u003ee\u003c/strong\u003e A significant difference is noted in the vertebral level of the stenosis. 3DCT, three-dimensional computed tomography; GRS, gastrorenal shunt; NS, non-significant, * p \u0026lt; 0.05\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6424084/v1/07050cc08657fbbab337b152.png"},{"id":87242093,"identity":"14f4236d-ab4d-4a67-8f05-f81dec3fd8f9","added_by":"auto","created_at":"2025-07-22 01:41:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":160300,"visible":true,"origin":"","legend":"\u003cp\u003eAgreement between 3DCT-Portography and GRS venography based on Bland–Altman analysis. \u003cstrong\u003ea b c d \u003c/strong\u003eBland–Altman analysis showing good agreement between the two modalities in the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, or stenosis rate. \u003cstrong\u003ee\u003c/strong\u003e A fixed bias is observed in the vertebral level of the stenosis. 3DCT, three-dimensional computed tomography; GRS, gastrorenal shunt\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6424084/v1/3fc36ea138303dc49f094be2.png"},{"id":87244319,"identity":"1ac4f2df-fbad-42da-8271-f52de4748f55","added_by":"auto","created_at":"2025-07-22 02:13:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1534022,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6424084/v1/25b2adb0-0ef6-4f87-93da-33e7f0474c14.pdf"},{"id":87242708,"identity":"bc1aaa7a-8e36-4eb4-b6a7-0ae1ce3e98b3","added_by":"auto","created_at":"2025-07-22 01:49:57","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":476403,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.docx","url":"https://assets-eu.researchsquare.com/files/rs-6424084/v1/8336e9eb7dd57a8954bb08ae.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eMorphological Analysis of Gastrorenal Shunts Using Three-dimensional Computed Tomography-Portography: A Comparison with Intraoperative Venography During Balloon-occluded Retrograde Transvenous Obliteration\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eGastric varices are serious complications that occur in approximately 20% of the patients with portal hypertension [1]. Although less likely to rupture than esophageal varices, rupture of gastric varices can lead to massive bleeding and remains associated with a high mortality rate of 15\u0026ndash;25%, even in recent years [2\u0026ndash;4]. Balloon-occluded retrograde transvenous obliteration (BRTO) is an endovascular treatment for gastric varices. In BRTO, the gastrorenal shunt, which serves as the efferent vein of the varices, is occluded with a balloon, and a sclerosant is injected into the varices [5\u0026ndash;7]. The recurrence rate after BRTO is less than 10% [8\u0026ndash;10], and the procedure has become widely accepted worldwide as an effective treatment for gastric varices [11\u0026ndash;13]. To ensure a successful BRTO, the sclerosant must be injected extensively from the efferent vein into the varices and upstream of the afferent veins. A thorough understanding of the anatomy and hemodynamics of gastric varices is essential for effective treatment.\u003c/p\u003e\n\u003cp\u003eGastric varices receive blood from the left gastric, posterior gastric, and short gastric veins, and drain into the left inferior phrenic, paraesophageal, azygos, and cardiophrenic veins. Among these, the left inferior phrenic vein plays a central role as an efferent pathway [14\u0026ndash;16]. The left inferior phrenic vein originates near the diaphragm, joins the gastric varices at the serosa-free area of the gastric fundus, and divides into transverse and descending branches that return to the systemic circulation. The transverse branch runs horizontally below the diaphragm and drains directly into the inferior vena cava, whereas the descending branch courses caudally, joins the left adrenal vein, and flows into the left renal vein [16]. This descending pathway is dilated and functions as a gastrorenal shunt, serving as a major portosystemic collateral in portal hypertension [14\u0026ndash;16]. The gastrorenal shunt descends from the perigastric area into the retroperitoneum with marked tortuosity. Multiple stenoses and angulations exist along its course, and several fine tributaries join, giving rise to the complex shunt morphology. In BRTO, the catheter must be advanced retrogradely into the appropriate site within the shunt; however, owing to this anatomical complexity, catheter manipulation is often technically challenging.\u003c/p\u003e\n\u003cp\u003eAlthough several anatomical studies have examined the left inferior phrenic vein [16\u0026ndash;20], few have focused on the morphology of the gastrorenal shunt itself [21]. This study aimed to characterize the anatomical features of the shunt outlet relevant to catheter manipulation in BRTO using three-dimensional CT (3DCT)-portography and evaluate its concordance with intraoperative venography findings.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis retrospective study was approved by the Ethics Committee of Fujisawa City Hospital (approval no. F2024027) and conducted in accordance with the Ethical Guidelines for Life Science and Medical Research Involving Human Subjects issued by the Ministry of Health, Labour and Welfare; the Ministry of Education, Culture, Sports, Science and Technology; and the Ministry of Economy, Trade and Industry of Japan. Because this study involved the retrospective use of medical records and imaging data, the requirement for written informed consent was waived and consent was obtained via an opt-out process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA database of patients who underwent BRTO for gastric varices at our institution between February 2017 and October 2024 was retrospectively reviewed. Patients were excluded if dynamic contrast-enhanced computed tomography (CT) was not performed preoperatively, BRTO was performed via the transverse branch of the left inferior phrenic vein, or intraoperative venography was performed using carbon dioxide. Clinical background, endoscopic and imaging findings, and procedural details were obtained from electronic medical records.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreprocedural Contrast-Enhanced CT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA bolus injection of an iodinated contrast agent (460 mgI/kg) was administered via a peripheral vein at 3.0\u0026ndash;4.0 mL/s. The arterial, portal venous, and delayed phases were acquired at 40, 60, and 120 s after injection, respectively. All the phases were obtained at 100 keV. Using dedicated image processing software (ZAIO Station System, Amin), 3DCT-portography of the gastric varices, gastrorenal shunt, left renal vein, and vertebral column, was reconstructed.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIntraoperative Gastrorenal Shunt Venography\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring BRTO, an 8-Fr guiding sheath was inserted via the right femoral or internal jugular vein and advanced to the outlet of the gastrorenal shunt through the left renal vein. A 5.2-Fr balloon catheter was inserted through the sheath and positioned near the shunt outlet. Manual injection of 5\u0026ndash;7 mL iodinated contrast medium was administered. The balloon catheter was advanced deeper into the shunt, and venography was performed under balloon occlusion. Once adequate opacification of the varices and afferent veins was confirmed, the sclerosant was injected from that position. The balloon catheter was left in place overnight and was removed the following day.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMeasurements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e3DCT-portography was used to assessed the presence of stenosis and angulation near the shunt outlet and the following parameters were measured:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eDistance from the left renal vein to the stenosis (mm), vertebral level\u003c/li\u003e\n \u003cli\u003eStenotic diameter (A) (mm)\u003c/li\u003e\n \u003cli\u003eDiameter of the common trunk with the left adrenal vein (B) (mm)\u003c/li\u003e\n \u003cli\u003eStenosis rate: (1 \u0026minus; A/B) \u0026times; 100 (C) (%)\u003c/li\u003e\n \u003cli\u003eAngle of the most prominent angulation (\u0026deg;)\u003c/li\u003e\n \u003cli\u003eDistance from the stenosis to the site of greatest angulation (mm)\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eVertebral levels were divided into the upper, middle, and lower thirds, and the intervertebral spaces were considered at one level. For statistical analysis, each level was assigned a numerical value at regular intervals (e.g., upper L2 = 0, L1/2 = 0.5, lower L1 = 1, middle L1 = 1.5, and upper L1 = 2), extending from L2 to T10.\u003c/p\u003e\n\u003cp\u003eThe following parameters were also measured using intraoperative gastrorenal shunt venography and compared with those obtained using 3DCT-portography:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eDistance from the left renal vein to the stenosis (mm), vertebral level\u003c/li\u003e\n \u003cli\u003eStenotic diameter (a) (mm)\u003c/li\u003e\n \u003cli\u003eDiameter of the common trunk (b) (mm)\u003c/li\u003e\n \u003cli\u003eStenosis rate: (1 \u0026minus; a/b) \u0026times; 100 (c) (%)\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical tests were performed to compare the measurements between 3DCT-portography and gastrorenal shunt venography. Paired t-tests were used for normally distributed data and the Wilcoxon signed-rank test was used for non-normally distributed data. Bland‒Altman analysis was conducted to assess the agreement between the two modalities and to evaluate fixed and proportional biases. All analyses were performed using the Modified R Commander (version 4.4.2), with a p-value \u0026lt; 0.05 considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eDuring the study period, 22 BRTO procedures were performed on 20 patients. Of these, three cases were excluded, and a total of 19 cases (14 men, 5 women; mean age, 66.1 \u0026plusmn; 9.6 years) were included in the final analysis. The patient characteristics are summarized in Table 1.\u003c/p\u003e\n\u003cp\u003eOn 3DCT-portography, multiple stenoses were identified within the gastrorenal shunt. In all cases, a stenosis was observed just above the common trunk with the left adrenal vein, located 17 \u0026plusmn; 4.7 mm from the left renal vein. Additionally, a marked dorsal angulation (62.9 \u0026plusmn; 18.4\u0026deg;) was noted 20.1 \u0026plusmn; 10.3 mm cranial to the stenosis. Detailed results are presented in Table 2 and Figure 1.\u003c/p\u003e\n\u003cp\u003eComparison between 3DCT-portography and gastrorenal shunt venography revealed no statistically significant differences in the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, or stenosis rate. However, a significant difference was observed in the vertebral stenosis level (p = 0.0022) (Figure2).\u003c/p\u003e\n\u003cp\u003eBland\u0026ndash;Altman analysis showed no fixed or proportional bias in the measurements of the distance to the stenosis, stenotic diameter, common trunk diameter, or stenosis rate between 3DCT-portography and venography, indicating a high level of agreement between the two modalities. In contrast, a significant fixed bias was identified at the vertebral level of the stenosis (p = 0.002153), with 3DCT-portography showing a lower position by 0.79 vertebral levels (95% confidence interval: \u0026ndash;1.25 to \u0026ndash;0.33) (Figure 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ePatient characteristics\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"399\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eCharacteristics \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003en=18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eAge (mean\u0026plusmn;SD, years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e66.1\u0026plusmn;9.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eSex（male/female）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e14/5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eBMI（mean\u0026plusmn;SD, kg/m\u003csup\u003e2\u003c/sup\u003e）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e27.1\u0026plusmn;4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eDisease origin（virus/alcohol/NASH/other）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e5/7/3/4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eChild\u0026ndash;Pugh Class（A/B/C）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e16/2/1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eChild\u0026ndash;Pugh score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e5.8\u0026plusmn;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eAscites（no/yes）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e17/2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eHCC（no/yes）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e16/3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eEsophageal varices（no/yes）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e10/9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eHepatic encephalopathy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e19/0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003ePortal vein thrombosis（no/yes）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e18/1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003eEndoscopic evaluation of gastric varices\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e \u0026nbsp;Location; Lg-f/Lg-c/Lg-cf\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e11/2/6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e \u0026nbsp;Form; F1/F2/F3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e1/13/5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e\u0026nbsp; Color; Cw/Cb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e7/12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e\u0026nbsp; Red-Color sign (no/yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e17/2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e\u0026nbsp; Mucosal findings (no/yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e15/4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75.8794%;\"\u003e\n \u003cp\u003e\u0026nbsp; Bleeding findings (no/yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 24.1206%;\"\u003e\n \u003cp\u003e18/1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eSD, standard deviation; NASH,\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003enon-alcoholic steatohepatitis; HCC, hepatocellular carcinoma\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eComparison of Measurements Between 3DCT-Portography and GRS Venography\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"567\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e3DCT-Portography\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003eGRS Venography\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eDistance from LRV to Stenosis (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e17.0\u0026plusmn;4.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e17.4\u0026plusmn;5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e0.303\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eStenotic Diameter (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e5.6\u0026plusmn;1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e5.1\u0026plusmn;1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e0.056\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eCommon Trunk Diameter (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e9.6\u0026plusmn;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e9.1\u0026plusmn;2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e0.166\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eStenosis Rate (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e40.9\u0026plusmn;13.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e43.0\u0026plusmn;11.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e0.399\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003eVertebral Level of Stenosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e1.8\u0026plusmn;1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003e2.6\u0026plusmn;0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e0.0022\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 38.3392%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003eupper L1 to mid L2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25.7951%;\"\u003e\n \u003cp\u003elower T12 to upper L1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10.0707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e3DCT, three-dimensional computed tomography; GRS, gastrorenal shunt; LRV, left renal vein\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study evaluated the morphology of the gastrorenal shunt outlet relevant to BRTO procedures using preoperative 3DCT-portography. In all cases, stenosis was observed just above the common trunk with the left adrenal vein and a marked dorsal angulation was present cranial to this site. The morphological measurements obtained from 3DCT-portography, including the distance from the left renal vein to the stenosis, stenotic diameter, diameter of the common trunk, and stenosis rate, showed no significant differences compared to those obtained by intraoperative venography, demonstrating high concordance between the two modalities.\u003c/p\u003e\n\u003cp\u003eSince the 2000s, several studies have described the use of CT to visualize the vascular anatomy of gastric varices [22\u0026ndash;24]. The introduction of multislice CT-enabled high-resolution imaging and facilitated the reconstruction of vascular anatomy using multi planar reconstruction (MPR) and volume rendering (VR) techniques. With further advances in CT hardware and software, it is now possible to clearly depict the complex vascular anatomy of gastric varices. In this study, 3DCT-portography accurately reproduced the structure of the gastrorenal shunt and corresponded well with the intraoperative venography findings. This modality is expected to be useful for preoperative catheter simulation and device selection because it provides detailed anatomical information. However, a significant difference was observed in the vertebral level of the stenosis, with 3DCT-portography showing a lower position by a mean of 0.79 levels. This discrepancy is likely because of the differences in the respiratory phase during image acquisition; dynamic contrast-enhanced CT was performed during inspiration, whereas venography was performed during expiration. Meanwhile, the distance from the left renal vein to the stenosis showed no significant difference between the two modalities. Therefore, the position of the stenosis on 3DCT-portography should be evaluated based not only on the vertebral level but also on its distance from the left renal vein.\u003c/p\u003e\n\u003cp\u003eThe use of 3DCT-portography is already considered essential for preoperative imaging prior to BRTO. Recently, fusion of preoperative 3DCT-portography with intraoperative fluoroscopy has been attempted to enable more effective and less invasive procedures [21]. Using 3DCT-portography as a roadmap may help reduce the number of intraoperative imaging runs, as well as the total volume of contrast medium and fluoroscopy time.\u003c/p\u003e\n\u003cp\u003eIn a comprehensive review of BRTO procedures, Wael et al. were the first to address the morphology of a gastrorenal shunt and its influence on catheter manipulation [15,25]. They noted that web-like narrowing is often present at the junction of the gastrorenal shunt-proper and the left adrenal vein, which may impede the passage of a catheter or guidewire. Thus, attention to the branching angle of gastrorenal shunt-proper is essential for safe catheter navigation. In our study, stenosis was observed just above the common trunk in all patients, and marked dorsal angulation was noted cranially. This angulation likely corresponded to the transition zone between the intraperitoneal and retroperitoneal portions of the shunt. During retrograde catheterization of the shunt, not only stenosis but also angulation can hinder device advancement. Unintended catheter manipulation may increase the risk of vascular injury; therefore, surgeons should carefully consider the anatomy, from the stenosis to the point of angulation.\u003c/p\u003e\n\u003cp\u003eTo date, no histopathological studies have investigated the nature of the stenosis observed within gastrorenal shunts. Araki et al. analyzed venography of the left inferior phrenic vein during adrenal vein sampling and identified a \u0026lsquo;valvular structure\u0026rsquo; at the caudal end of the vein near its junction with the left adrenal vein [20]. This structure was located 16.4 \u0026plusmn; 4.7 mm from the left renal vein, corresponding closely with the site of stenosis observed in our study (17.0 \u0026plusmn; 4.7 mm). As Araki et al. studied patients without portal hypertension, our findings suggest that stenosis just above the common trunk may be a congenital feature independent of portal hypertension. If, as Araki et al. suggest, this represents a downward-facing valve, it could explain the difficulty in advancing catheters and guidewires through this site despite the relatively mild degree of stenosis (mean stenosis rate: 40.9 \u0026plusmn; 13.9%). Further investigations using modalities, such as intravascular or endoscopic ultrasound may help clarify the nature of this structure.\u003c/p\u003e\n\u003cp\u003eThis study had some limitations. First, the sample size was small. Second, respiratory motion may have influenced the measurements. As mentioned earlier, CT was performed during inspiration, whereas venography was performed during expiration, which may have contributed to the significant difference in the vertebral level. Moreover, the increased venous return during inspiration and possible Valsalva effect may have led to an overestimation of the venous diameter on CT. Third, intraoperative venography was manually performed, and variations in the contrast volume or injection rate may have affected the image quality and measurements.\u003c/p\u003e\n\u003cp\u003eIn conclusion, stenosis was consistently identified just above the common trunk of the left adrenal vein and marked dorsal angulation was observed cranial to the stenosis. Preoperative 3DCT-portography accurately depicted the structure of the gastrorenal shunt and corresponded well with intraoperative venography. The anatomical features revealed in this study may contribute to safer and more effective endovascular treatment for gastric varices.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eBRTO, Balloon-occluded retrograde transvenous obliteration\u003c/p\u003e\n\u003cp\u003e3DCT, Three-dimensional computed tomography\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSD, Standard deviation\u003c/p\u003e\n\u003cp\u003eNASH, Non-alcoholic steatohepatitis\u003c/p\u003e\n\u003cp\u003eHCC, Hepatocellular carcinoma\u003c/p\u003e\n\u003cp\u003eGRS, Gastrorenal shunt\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eY. F. conceived and designed the study. Y.F., M.T., Y.N., and K.Y. were involved in data acquisition and curation. Y.F. performed the statistical analysis and drafted and revised the manuscript. All authors reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe imaging data analysed during this study are not publicly available due to patient privacy concerns but are available from the corresponding author upon reasonable request with appropriate ethical approvals.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGarcia-Tsao G, Abraldes JG, Berzigotti A, Bosch J (2017) Portal hypertensive bleeding in cirrhosis: Risk stratification, diagnosis, and management: 2016 practice guidance by the American Association for the study of liver diseases. Hepatology 65:310\u0026ndash;335. https://doi.org/10.1002/hep.28906\u003c/li\u003e\n\u003cli\u003eGiri S, Jearth V, Seth V, Darak H, Sundaram S (2023) Comparison of efficacy and safety of endoscopic and radiological interventions for gastric varices: A systematic review and network meta-analysis. Clin Exp Hepatol 9:57\u0026ndash;70. https://doi.org/10.5114/ceh.2023.126077\u003c/li\u003e\n\u003cli\u003eTeng W, Chen W-T, Ho Y-P, Jeng W-J, Huang C-H, Chen Y-C, Lin S-M, Chiu C-T, Lin C-Y, Sheen I-S (2014) Predictors of mortality within 6 weeks after treatment of gastric variceal bleeding in cirrhotic patients. Medicine (Baltimore) 93:e321. https://doi.org/10.1097/md.0000000000000321\u003c/li\u003e\n\u003cli\u003eSarin SK, Lahoti D, Saxena SP, Murthy NS, Makwana UK (1992) Prevalence, classification and natural history of gastric varices: a long-term follow-up study in 568 portal hypertension patients. Hepatology 16:1343\u0026ndash;1349. https://doi.org/10.1002/hep.1840160607\u003c/li\u003e\n\u003cli\u003eKanagawa H, Mima S, Kouyama H, Gotoh K, Uchida T, Okuda K (1996) Treatment of gastric fundal varices by balloon-occluded retrograde transvenous obliteration. J Gastroenterol Hepatol 11:51\u0026ndash;58. https://doi.org/10.1111/j.1440-1746.1996.tb00010.x\u003c/li\u003e\n\u003cli\u003eHirota S, Matsumoto S, Tomita M, Sako M, Kono M (1999) Retrograde transvenous obliteration of gastric varices. Radiology 211:349\u0026ndash;356. https://doi.org/10.1148/radiology.211.2.r99ma25349\u003c/li\u003e\n\u003cli\u003eSaad WEA (2012) Balloon-occluded retrograde transvenous obliteration of gastric varices: concept, basic techniques, and outcomes. Semin Intervent Radiol 29:118\u0026ndash;128. https://doi.org/10.1055/s-0032-1312573\u003c/li\u003e\n\u003cli\u003eYu Q, Liu C, Raissi D (2021) Balloon-occluded retrograde transvenous obliteration versus transjugular intrahepatic portosystemic shunt for gastric varices: A meta-analysis: A meta-analysis. J Clin Gastroenterol 55:147\u0026ndash;158. https://doi.org/10.1097/MCG.0000000000001305\u003c/li\u003e\n\u003cli\u003eWang ZW, Liu JC, Zhao F, Zhang WG, Duan XH, Chen PF, Yang SF, Li HW, Chen FW, Shi HS, Ren JZ (2020) Comparison of the effects of TIPS versus BRTO on bleeding gastric varices: A meta-analysis. Can J Gastroenterol Hepatol 2020:5143013. https://doi.org/10.1155/2020/5143013\u003c/li\u003e\n\u003cli\u003ePaleti S, Nutalapati V, Fathallah J, Jeepalyam S, Rustagi T (2020) Balloon-occluded retrograde transvenous obliteration (BRTO) versus transjugular intrahepatic portosystemic shunt (TIPS) for treatment of gastric varices because of portal hypertension: A systematic review and meta-analysis: A systematic review and meta-analysis. J Clin Gastroenterol 54:655\u0026ndash;660. https://doi.org/10.1097/MCG.0000000000001275\u003c/li\u003e\n\u003cli\u003eHenry Z, Patel K, Patton H, Saad W (2021) AGA clinical practice update on management of bleeding gastric varices: Expert review. Clin Gastroenterol Hepatol 19:1098\u0026ndash;1107.e1. https://doi.org/10.1016/j.cgh.2021.01.027\u003c/li\u003e\n\u003cli\u003eBoregowda U, Umapathy C, Halim N, Desai M, Nanjappa A, Arekapudi S, Theethira T, Wong H, Roytman M, Saligram S (2019) Update on the management of gastrointestinal varices. World J Gastrointest Pharmacol Ther 10:1\u0026ndash;21. https://doi.org/10.4292/wjgpt.v10.i1.1\u003c/li\u003e\n\u003cli\u003eKaplan DE, Ripoll C, Thiele M, Fortune BE, Simonetto DA, Garcia-Tsao G, Bosch J (2024) AASLD Practice Guidance on risk stratification and management of portal hypertension and varices in cirrhosis. Hepatology 79:1180\u0026ndash;1211. https://doi.org/10.1097/HEP.0000000000000647\u003c/li\u003e\n\u003cli\u003eSabri SS, Saad WEA (2011) Anatomy and classification of gastrorenal and gastrocaval shunts. 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Abdom Imaging 35:1\u0026ndash;7. https://doi.org/10.1007/s00261-009-9506-y\u003c/li\u003e\n\u003cli\u003eKiyosue H, Ibukuro K, Maruno M, Tanoue S, Hongo N, Mori H (2013) Multidetector CT anatomy of drainage routes of gastric varices: a pictorial review. Radiographics 33:87\u0026ndash;100. https://doi.org/10.1148/rg.331125037\u003c/li\u003e\n\u003cli\u003eSaad WEA, Kitanosono T, Koizumi J, Hirota S (2013) The conventional balloon-occluded retrograde transvenous obliteration procedure: indications, contraindications, and technical applications. Tech Vasc Interv Radiol 16:101\u0026ndash;151. https://doi.org/10.1053/j.tvir.2013.02.003\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Gastrorenal shunt, Gastric varices, Balloon-occluded retrograde transvenous obliteration (BRTO), Portal hypertension, Three-dimensional computed tomography (3DCT)","lastPublishedDoi":"10.21203/rs.3.rs-6424084/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6424084/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e\u003cbr\u003e\nBalloon-occluded retrograde transvenous obliteration (BRTO) is an endovascular treatment for gastric varices. Successful BRTO requires deep catheterization of the gastrorenal shunt which constitutes the main efferent pathway of the varices. However, the complex anatomy of the shunt can complicate catheter manipulation. This study aimed to clarify the morphological features of gastrorenal shunts relevant to BRTO using three-dimensional computed tomography (3DCT)-portography and to evaluate its concordance with intraoperative venography.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003cbr\u003e\nPatients who underwent BRTO between January 2017 and October 2024 were included. Preoperative dynamic contrast-enhanced CT was used to reconstruct 3DCT-portography images. The morphological evaluation focused on stenosis and angulation of the shunt. Measurements compared between 3DCT-portography and intraoperative venography included the distance from the left renal vein to the stenosis, vertebral level of the stenosis, stenotic diameter, common trunk diameter with the left adrenal vein, and stenosis rate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003cbr\u003e\nNineteen patients were included. All showed a stenosis just above the common trunk with the left adrenal vein (17 ± 4.7 mm from the left renal vein). A marked dorsal angulation (62.9 ± 18.4°) was observed cranial to the stenosis. No significant differences were found between the two modalities in most measurements, indicating high concordance. However, a significant difference was noted at the vertebral level (p = 0.0022), with 3DCT-portography showing a lower position.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e: Consistent stenosis was observed just above the common trunk, with a dorsal angulation cranial to it. The gastrorenal shunt anatomy was effectively visualized using 3DCT-portography, which showed good correlation with the intraoperative venography findings.\u003c/p\u003e","manuscriptTitle":"Morphological Analysis of Gastrorenal Shunts Using Three-dimensional Computed Tomography-Portography: A Comparison with Intraoperative Venography During Balloon-occluded Retrograde Transvenous Obliteration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-22 01:41:52","doi":"10.21203/rs.3.rs-6424084/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7cd84be8-f68c-4f9b-b11f-94a0d9e77f3b","owner":[],"postedDate":"July 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-22T01:41:52+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-22 01:41:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6424084","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6424084","identity":"rs-6424084","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}