Hepatic pseudolesion and pseudotumor due to third inflow: Prevalence and correlation with liver fibrosis on multi-phasic MDCT

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1 Hepatic pseudolesion and pseudotumor due to third inflow: Prevalence and correlation with liver fibrosis on multi-phasic MDCT Poster No.: C-1940 Congress: ECR 2015 Type: Scientific Exhibit Authors: K. Yoshida, S. Kobayashi, O. Matsui, N. Yoneda, D. Inoue, K. Kozaka, T. Gabata; Kanazawa/JP Keywords: Physiological studies, CT, Vascular, Liver, Abdomen, Cirrhosis DOI: /ecr2015/C-1940 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 21

2 Aims and objectives Hepatic pseudolesions and pseudotumors are tumorous intrahepatic lesions occasionally mimicking hepatic tumors. Especially, the lesions due to the third inflow are observed on determinate area, such as adjacent to the falciform ligament, around the gallbladder fossa, and in the posterior aspect of Segment IV of the liver. Hepatic pseudolesions and pseudotumors of the third inflow area are frequently encountered on recent radiological modalities. However, the prevalence and the relationship with the presence of hepatic pseudolesions and the progression of liver fibrosis have not been extensively investigated. The purpose of this study was to analyze the prevalence of hepatic pseudolesion and/ or pseudotumor due to the third inflow using multi-phasic MDCT special reference to the correlation with the degree of liver fibrosis. Methods and materials The definitions of the terms are as below Pseudolesoin is defined as focal mass-like finding visualized only on imaging studies without parenchymal change. Pseudotumor is defined as focal mass-like parenchymal change of the liver with preserved internal hepatocyte, angioarchitecture and normal liver function (such as focal fatty change, focal spared area, and focal hyperplastic change). Third inflow is defined as aberrant veins supplying small areas of the liver tissue and communicating with intrahepatic portal vein branches. During the period from Jan 2010 to Dec 2012, 1199 consecutive patients have examined liver fibrosis with liver biopsy or surgical resection in our hospital. Inclusion and exclusion criteria and selection process of the study cohort is shown in flowchart (Fig.1). Finally, 519 patients including 200 patients with healthy liver who underwent dynamic CT were enrolled in this study: F0 n = 202, F1 n = 48, F2 n = 55, F3 n = 101, F4 n = 113 in METAVIR classification. Clinical information of each group including age, sex, background liver, interval between CT and fibrosis examinations, and status of malignant tumor / fatty liver, are listed in Fig.2. Dynamic CT protocol is shown in Fig.3. All CT images were interpreted retrospectively by three experienced abdominal radiologists, and the following MDCT findings adjacent to the falciform ligament, around the gallbladder fossa, and in posterior aspect of the Segment IV were analyzed. Page 2 of 21

3 The presence or absence of pseudolesion (hypodense only on arterial and/ or portal dominant phase) The presence or absence of focal fatty change (hypodense on all phases) The presence or absence of focal spared area (hyperdense on all phases) Disagreements were resolved by consensus. Images for this section: Fig. 1: Inclusion and exclusion criteria and selection process of the study cohort is shown in flowchart. Page 3 of 21

4 Fig. 2: The main clinical characteristics of each patients group Page 4 of 21

5 Fig. 3: Dynamic CT protocol of this study Page 5 of 21

6 Results In imaging of normal liver, hypodensity adjacent to the falciform ligament was found in 58% of cases on portal venous phase images. Among them, hypodensity indicating associated focal fatty change was also visualized in 8.5% of cases (Fig.4). In cases with liver fibrosis, prevalence of the abnormality adjacent to the falciform ligament decreased gradually with liver fibrosis, 48% in F1, 17% in F2, 6% in F3, and 1% in F4 (Fig.4). Typical cases of pseudolesion and/or pseudotumor adjacent to the falciform ligament in each fibrosis group are shown in Fig Pseudolesion around the gallbladder fossa and in posterior aspect of the Segment IV was rarely found in 1% and 2%, respectively (Fig.12). Pseudotumor, focal spared area was found in 13% around the gallbladder fossa and 7.5% in posterior aspect of the Segment IV (Fig.12). The prevalence of pseudotumor (focal spared area) around the gallbladder fossa and in posterior aspect of the Segment IV was rarely found in F1-4 groups. Typical cases of pseudotumor (focal spared area) around the gallbladder fossa and in posterior aspect of the Segment IV are shown in Fig.13. Images for this section: Page 6 of 21

7 Fig. 4: The prevalence of hepatic pseudolesion and/or pseudotumor adjacent to the falciform ligament Page 7 of 21

8 Fig. 5: Pseudolesion adjacent to the falciform ligament of Segment IV in a 62-year-old woman with normal liver. Dynamic CT showed hypodense lesion adjacent to the falciform ligament of Segment IV on portal venous phase. The lesion cannot be detected on other phases. Page 8 of 21

9 Fig. 6: Focal fatty change adjacent to the falciform ligament of Segment IV in a 70-yearold man with normal liver. Precontrast CT showed slight hypodense lesion adjacent to the falciform ligament of Segment IV. The lesion was clearly identified as hypodense on portal venous phase. Page 9 of 21

10 Fig. 7: Focal fatty change adjacent to the falciform ligament of Segment IV in a 70year-old man with normal liver (same patient of Fig.6). The lesion showed hypointense on opposed phase of gradient echo T1-weighted image. This lesion was diagnosed as pseudotumor (focal fatty change). Page 10 of 21

11 Fig. 8: Pseudolesion adjacent to the falciform ligament of Segment IV in a 40-yearold man with liver fibrosis (F1). Dynamic CT showed hypodense lesion adjacent to the falciform ligament of Segment IV on portal venous phase. Page 11 of 21

12 Fig. 9: Pseudolesion adjacent to the falciform ligament of Segment IV in a 57-yearold man with liver fibrosis (F2). Dynamic CT showed hypodense lesion adjacent to the falciform ligament of Segment IV on portal venous phase. Page 12 of 21

13 Fig. 10: A 77-year-old woman with liver fibrosis (F3). Dynamic CT did not show any hepatic lesions. paraumbilical vein is observed (arrow). Page 13 of 21

14 Fig. 11: A 77-year-old man with liver fibrosis (F4). Dynamic CT did not show any hepatic lesions. Page 14 of 21

15 Fig. 12: The prevalence of hepatic pseudolesion and/or pseudotumor around the gallbladder fossa and in posterior aspect of the Segment IV Page 15 of 21

16 Fig. 13: Representative cases of hepatic pseudotumor (focal spared area in fatty liver) found around gallbladder fossa and in posterior aspect of Segment IV. Page 16 of 21

17 Conclusion Various types of psedolesions or pseudotumors are observed in the liver parenchyma receiving non-portal venous blood supply, most commonly due to the third inflow into the liver. Some of the splanchnic venous flow does not join the portal vein in the extrahepatic portion, these venous flow are directly enters the liver independently, and then flows into the hepatic sinusoids. Such aberrant veins are called "third inflow" vessels to the liver. There are two kinds of third inflow veins that supply venous blood to the liver: one are the veins originating from a digestive organ, such as the cholecystic vein and parabiliary venous system, and the others are systemic veins, such as the epigastric-paraumbilical venous system, and capsular veins. Fig.14 shows a typical location of the third inflow into the liver. According to previous reports, pseudolesion adjacent to the falciform ligament was founded 1-43% in normal liver, and not detected with liver cirrhosis. Our study indicates that pseudolesion adjacent to the falciform ligament is frequently founded in approximately 60% of cases in normal liver, and focal fatty change are found in 8.5% of the cases. The prevalence of pseudolesion and/or pseudotumor showed a tendency to show gradual decrease according with the advantage of liver fibrosis. This pseudolesion and/or pseudotumor thought to be caused by the presence of "hepatopetal" epigastricperiumbilical venous flow that is called inferior vein of Sappey. In normal liver, the blood flow of inferior vein of Sappey regularly runs toward hepatopetal direction and causes pseudolesion and/or pseudotumor in radiological images. However, with the progression of liver fibrosis, the flow direction of inferior vein of Sappey changes changes from hepatopetal to "hepatofugal" due to portal hypertension. This hepatofugal flow is often recognized as paraumbilical veins in patients with advanced cirrhosis with portal hypertension. In conclusion, the pseudolesion and/or pseudotumor adjacent to the falciform ligament were often seen in approximately 60% of normal liver cases on portal venous phase images on multi-phasic MDCT. The frequency of the pseudolesion and/or pseudotumor adjacent to the falciform ligament shows negative correlation with the progression of the degree of liver fibrosis. In normal liver, pseudolesion around the gallbladder fossa or in posterior aspect of the Segment IV was hardly recognized on multi-phasic MDCT. However, in fatty liver, pseudotumor (as the focal spared area) around the gallbladder fossa or in posterior aspect of the Segment IV was frequently founded. Images for this section: Page 17 of 21

18 Fig. 14: Illustrations of typical locations of pseudolesion and/or pseudotumor, and related third inflow veins. Page 18 of 21

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21 Kobayashi S, Matsui O, Kadoya M et al.: CT arteriographic confirmation of focal hepatic fatty infiltration adjacent to the falciform ligament associated with drainage of inferior vein of Sappey: a case report. Radiat. Med. 19(1), (2001). 16) Kobayashi S, Matsui O, Gabata T: Pseudolesion in segment IV of the liver adjacent to the falciform ligament caused by drainage of the paraumbilical vein: demonstration by power Doppler ultrasound. Br. J. Radiol. 74(879), (2001). Page 21 of 21