Diagnostic approach of hypervascular liver masses

Transcription

1 Diagnostic approach of hypervascular liver masses Poster No.: C-2187 Congress: ECR 2014 Type: Educational Exhibit Authors: A. Ben Miled, M. Larguech, O. AZAIZ, A. Neffati, M. Fekih, M BEN MESSAOUD, H. Mizouni ; Tunis/TN, Tunis, Tunisia/TN, 3 TN Keywords: Cancer, Diagnostic procedure, Ultrasound, MR, CT, Liver, Abdomen DOI: /ecr2014/C-2187 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 55

2 Learning objectives -To recognize the different hypervascular hepatic tumors and their typical imaging aspects mainly in CT and MRI. -To read out the semiological elements that help to approach the histological nature in less typical and atypical lesions. Background 1. Liver vascularization: The normal liver has a dual blood supply from the hepatic artery and the portal vein in an approximate 1:4 ratio. Hypervascular tumors are typically supplied mainly by arteries. This distinction is behind multiphase liver imaging protocols in which the liver is imaged in its entirety at several different time points following intravenous contrast administration: Arterial (at 30th sec), portal (at 70th sec ) and late phases. During the arterial phase, the normal liver enhances relatively little. Hypervascular tumors, appear as hyperdense lesions during arterial-phase since their arterial supply is significantly greater than that of the normal liver. 2. classification: Benign lesions of hepatocellular origin: Mainly "focal nodular hyperplasia( FNH )" and "adenoma" which are typically hypervascular. Malignant hypervascular primary hepatocellular lesions: Page 2 of 55

3 > Hepatocellular carcinoma (HCC) > Fibrolamellar carcinoma > peripheral cholangiocarcinoma Vascular liver lesions: Often appear hypervascular because they tend to follow the enhancement of the blood pool: > Hypervascular hemangiomas > Arteriovenous malformations > Angiosarcomas Hypervascular metastases to the liver: Most gastrointestinal malignancies that metastasize to the liver appears hypovascular on arterial and portal-venous phase imaging. Certain cancers such as metastatic neuroendocrine tumors: pancreatic neuroendocrine tumors. Carcinoids. gastrointestinal stromal tumors. tend to produce hypervascular metastases due to the greater recruitment of arterial blood supply. Rare hepatic lesions: May have a hypervascular appearance: such as glomus tumor and inflammatory pseudotumors. Page 3 of 55

4 Findings and procedure details Imaging Modalities: US: Ultrasound is an inexpensive and easily available imaging test for evaluation of liver lesions. It is highly sensitive for differentiation of solid from cystic liver lesion. However, routine transabdominal ultrasound is not as sensitive as computed tomography (CT) or magnetic resonance imaging (MRI) for detection and characterization of liver lesions. CT protocol: Triple phase: Non contrast, arterial, portal venous, equilibrium. Contrast: IV contrast, 2 ml/kg, 5mL/sec. Scan Method: Arterial phase: usual delay 30 sec Portal venous phase: at 70 sec delay. We scan the entire abdomen in this acquisition. Equilibrium Phase: at 180 sec delay. CT has a limited role in characterization of lesions smaller than 1 cm and it is t is associated with risk of radiation exposure. MRI Techniques: Sequences: 1. Coronal ultrafast spin-echo T2-weighted images. 2. Axial fast spin-echo (T2-weighted) images through the liver. 3. Diffusion-weighted sequence (DWI). Page 4 of 55

5 4. Axial 2D, T1 dual spoiled gradient-recalled echo sequence (SPGR) (out-of-phase and in phase imaging). 5. Dynamic injected gradient-echo with fat saturation sequences: arterial time(30 sec), portal venous (60 seconds), and delayed (varies from 90 seconds to several minutes. Contrast: Gadolinium, IV: mmol/kg, 2 ml/s. Has a high lesion-to-liver contrast. It is not associated with risk of radiation exposure. The diagnosis approach: The appearance of the underlying liver parenchyma should be considered carefully in the differential diagnosis of hypervascular lesions. In noncirrhotic patient, hemangiomas are the most common benign hypervascular liver lesion followed by FNH, hepatic adenomas and hypervascular metastasis. Conversely, patients with cirrhotic liver morphology have a different spectrum of liver lesions, with HCC being the first lesion that must be excluded, followed by dysplastic and regenerative nodules. Tiny hypervascular peripheral arterial-portal shunts are also commonly seen in cirrhotic patients. 1. Benign lesions of hepatocellular origin: Both FNH and HCA are benign lesions, but they are managed quite differently. FNH is usually managed conservatively, and most cases do not require resection. Adenoma, on the other hand, can have serious clinical consequences, such as spontaneous hemorrhage or malignant transformation, and is commonly treated with surgical resection. Page 5 of 55

6 Focal nodular hyperplasia (FNH): The second most common benign liver tumor after hemangioma. Occurs most commonly in women (80-95% of the cases) in their third to fourth decades of life. Usually solitary (80%). FNH is an hamartomatous lesion due to disorganized growth pattern of hepatocytes and ducts forming an unencapsulated mass with abnormally structured vessels and bile ducts, subdivided into nodules by fibrous septa that may form stellate scar corresponding to a dense connective tissue which contains numerous abnormally thick walled arteries. At US: Homogeneous nonencapsulated lesion, slightly hypoechoic or isoechoic, with lobulated countours. The central scar is slightly hyperechoic. Color Doppler: Central feeding artery with a stellate or spoke-wheel pattern corresponding to the artery running from the central scar to fibrous septa. Spectral analysis shows an arterial flow with low resistive index. At CT: On precontrast CT scans, FNH is demonstrated as a focal hypodense or isodense mass. A central hypodense scar depicted in 30% of cases. On contrast enhanced CT, lesion enhances rapidly at the arterial phase. At the portal phase, enhancement decreases and the lesion may be either iso or slightly hyperdense. On delayed images, central scars may appear iso or hyperattenuating. 5 MRI criteria have been proposed to confirm FNH: Page 6 of 55

7 Isointense or a discrete hypointense T1, associated with an isointense or discrete hyperintense T2. The presence of hyperintense T2 central stellar scar. Lesion homogeneity apart the central scar. Dramatic enhancement in the arterial phase, followed by isointensity of the lesion during the portal venous phase with late enhancement of the central scar. Absence of capsule. Atypical FNH: Central scar: No scar is visible, especially in less than 3 cm FNH. Hypointense on T2-weight images. Hypodense or isodense on injected delayed scans. Enhancement: Rapid washout or delayed contrast enhancement. Lesion heterogeneity: 30%. Hyperintensity of the lesion on T1-weighted: fat deposition, hemorrhage. Pseudocapsule corresponding to dilated vessels and sinusoids around FNH. It is more irregular and incomplete than true capsule. Calcification. case 1: 64 year old man with FNH. Page 7 of 55

8 Fig. 1: Typical FNH at ultrasound. (a) US shows a homogeneous unencapsulated lesion. (b) Color Doppler demonstrates central feeding artery.(c) Spectral analysis shows an arterial flow. References: Radiology, La Rabta - Tunis/TN Page 8 of 55

9 Fig. 2: (a)precontrast CT scan demonstrates a focal hypodense lesion (b)arterial phase CT demonstrating strong enhancement within the segment VI of liver. (c) Portal phase CT image shows lesion attenuation. References: Radiology, La Rabta - Tunis/TN Page 9 of 55

10 Fig. 3: (a) Precontrast T1-weighted axial MR shows hypointense lesion within the segment VI. (b) T2-weighted axial MR image shows isointense lesion. Contrast enhanced MR demonstrates strong enhancement in the arterial phase (c),followed by isointensity of the lesion during (d) the portal venous phase. References: Radiology, La Rabta - Tunis/TN One criterion among the five criteria of typical HNF lacks: The visualisation of T2 hyperintense and delayed enhanced central scar. Therefore liver biopsy was performed confirming the diagnosis of FNH. Case 2: 50 year old man with typical FNH. Page 10 of 55

11 Fig. 4: Precontrast CT scan demonstrates a focal isodense lesion developed at segment IV of liver. Arterial phase CT demonstrating strong homogeneous enhancement of these mass. Portal phase CT image shows lesion attenuation similar to the liver. References: Radiology, La Rabta - Tunis/TN Page 11 of 55

12 Fig. 5: (a) T1-weighted axial MR shows homgeneous isointense, nonencapslated lesion at segment IV of liver with central hypointensity (arrow).(b) T2-weighted axial MR image shows homgeneous isointense lesion. Central scar is strongly hyperintense (arrow). (a-c) Pre and postcontrast T1-weighted axial MR images showing dramatic lesion enhancement on the arterial phase followed by attenuation during (d)portal and (e)delayed imaging. Note the scar enhancement on (e)delayed imaging (arrow). References: Radiology, La Rabta - Tunis/TN This imaging findings confitrmed the diagnosis of FNH. No more investigation was needed. Hepatocellular adenomas: It is a true neoplasm that is considered to occur under proliferative stimulation of hepatocytes. Page 12 of 55

13 Frequently occurs in women on estrogen/progesterone therapy, patients with glycogen storage disease and occasionally men chronically using anabolic steroids. They are composed of sheets of cells resembling normal hepatocytes containing abundant glycogen and lipid. Prominent arteries and draining veins are seen throughout the tumor, although normal portal triads are absent. Histologically benign, but they do have a small risk for malignant transformation into HCC, as well as a propensity for hemorrhage and rupture. Tissue biopsy is therefore mandatory to confirm diagnosis in cases in which the imaging findings are indeterminate. We distinguish 4 molecular type of adenoma: 1. HNF-alpha 1 mutated adenomas ( 35-45% ): Characterized by their marked steatosis and their benign course, motivating a conservative approach. 2. B2 catenin mutated adenomas (15-20% ): Affect mainly men. Associated with high risk of malignant transformation. 3. Inflammatory or telangiectasic adenomas ( 35-40% ): Occur in patient presenting a context of obesity, metabolic syndrome or steatohepatitis liver. Hemorrhagic complication may occurs if they exceed 5 cm. An associated B2 catenin mutation may exist in 10% of cases, with a risk of HCC transformation. 4. Nonspecific adenomas ( 10-20% ): Page 13 of 55

14 The imaging features of adenomas depend greatly on 2 features: the background echogenicity, density, or signal intensity of the liver; and the amount of lipid, hemorrhage, or fibrosis in the adenoma itself, which can vary widely. At US, its appearance can be variable. Color Doppler evaluation can be helpful, as peripheral and intratumoral vessels can be seen, with a flat continuous Doppler waveform in contrast to the usual pulsatile waveform of FNH and HCC. At CT calcifications may be present. MRI semiology is correlated with the different genotypes: Inflammatory adenoma Steatosic adenoma Hyper T2 Global signal dropout on out-of-phase imaging. Hypervascular at arterial phase Iso or hyper T2 Hyperintense to the liver at venous phase Slightly hypervascular at arterial phase Case 1: 23 year old woman with histologically confirmed inflammatory adenoma. Page 14 of 55

15 Fig. 6: (b)t2-weighted coronal MR image shows subtle hyperintense to normal liver(curved arrow) large and well circumscribed mass(staight arrow) in the right liver. It appears isointense on (a) precontrast T1-weightedimage. The mass shows homogeneous enhancement during (c) the arterial phase; and remains slightly hyperintense on (d) portal venous phase image. References: Radiology, La Rabta - Tunis/TN Liver adenomatosis (LA): LA is de#ned as the presence of more than 10 adenomas. It is a rare disease of unknown cause. Mean age at diagnosis is 32 years. Page 15 of 55

16 It is a rare condition in children, representing 8.4% of liver tumors in pediatric patients between the ages 5 and 20 years, and it can complicate the natural course of a metabolic liver disease such as glycogen storage disease types I and III. There is genetic origin of some liver adenomatosis associated with heterozygous HNF-1 alpha germline mutations in adults and children. The main complication is bleeding with intraperitoneal hemorrhage. Malignant transformation is possible. Liver adenomatosis and solitary hepatic adenomas are similar histologically. Three histologic forms of liver adenomatosis have been recently described: Steatotic, Peliotic Mixed Imaging features: There are no specific features on ultrasound. In general, CT and MR features are variable and depend on the size, vascularity, and the presence of hemorrhage, fat, or necrosis. LA may be undetected on unenhanced images or portal venous dominant phase images, since these masses consist almost entirely of uniform hepatocytes. Enhanced CT and MRI show hypervascularity in the arterial phase, usually uniform in the absence of hemorrhage or fat.the enhancement pattern is heterogeneous with larger lesions, and if fat and hemorrhage are present. There is a rapid wash-out of contrast on delayed phase images because of arteriovenous shunting, so that the lesions usually demonstrate similar or less enhancement as compared with normal liver parenchyma. Page 16 of 55

17 All these investigations are nonspecific and do not accurately record the nature and the number of the lesions. Histology is mandatory. Case 1: 17 year old boy with history of heditary dislipidemia and histologically proven liver adenomatosis and underlying liver steatosis. Fig. 7: (a) unenhanced T1-weighted axial in phase image shows multiple heterogeneous diffuse lesions within an enlarged liver. (b) out of phase T1 weighted image demonstrates that some lesions contains areas of fat: signal drop-out (arrow). (c) hyperintense lesions on T2-weighted image. (d)all lesions show strong arterial enhancement. Enhancing regions are mostly isointense to liver parenchyma in venous imaging. (e) In delayed phase, most lesions are slightly hypointense compared with Page 17 of 55

18 surrounding liver parenchyma. Two lesions with peripheral contrast enhancement are shown in this slice (arrows). References: Radiology, La Rabta - Tunis/TN 2. Vascular liver lesion: Cavernous hemangiomas: They are the most common benign tumors of the liver. Occur in women more likely than in men, at all ages. They are frequently in a subcapsular location, more commonly in the right lobe, especially the posterior segment. They are usually solitary but may be multiple. Usually asymptomatic Hypervascular hemangioma (HH) is atypical hepatic hemangiomas with an approximate incidence near to 16% of all angiomas Imaging features: Cavernous hemangiomas are hyperechoic at US and show typically, on Ct scans, a globular peripheral enhancement with slow progressive centripetal filling after bolus injection of contrast material; which leave no doubt about the diagnosis. HH tend to be seen as hypoechoic lesions at US. Color Doppler sonography may reveal intratumoral flows, large feeding arteries, and reversalof portal flow around the tumor. Knowledge of such sonographic findings may ensure an accurate sonographic diagnosis of these tumors CT findings are usually characteristic and specific. They consist of an early, complete, and homogenous high enhancement similar to that of the aorta in all phases. It is the main criteria to make differential diagnosis and avoid liver biopsy. At MRI, hepatic hemangiomas show typically bright signal intensity on T2 sequences which is one of the most reliable findings in the diagnosis. In HH, T2 signal intensity may be not as bright as cerebrospinal fluid. Page 18 of 55

19 Case 1: A 47-year-old woman with a history of stomach ulcer, presented with right hypochondriac pain. Fig. 8: US shows delineated and hypoechoic nodule of the segment VI. Power Doppler shows flow signals in and around. References: Radiology, La Rabta - Tunis/TN Page 19 of 55

20 Fig. 9: (a) Axial CT scan after contrast injection in arterial phase. Hepatic hypervascular hemangioma with similar enhancement to the aorta and early enhancement of parenchyma adjacent to the lesion. (b) Axial CT scan after contrast injection in portal phase. The hepatic hemangioma has the same enhancement than that of the aorta. References: Radiology, La Rabta - Tunis/TN Page 20 of 55

21 Fig. 10: Axial T2 weighed MRI sequence. The hepatic hemangioma has an atypical T2 signal intensity (arrow) which is not as bright as cerebrospinal fluid as usually found in hepatic hemangiomas. References: Radiology, La Rabta - Tunis/TN 3. Malignant hypervascular primary hepatocellular lesions: Hepatocellular Carcinoma (HCC) in cirrhotic liver: -HCC is the most common primary malignancy of the liver. -Cirrhosis is the first predisposing factor for HCC. It may be secondary to infectious (hepatitis), toxic (alcohol) or metabolic processes ( hemochromatosis, Wilson disease, #1-antitrypsin deficiency syndrome). -80% of HCC develops in a cirrhotic liver. -Usually associated with elevation of alpha-fetoprotein. Page 21 of 55

22 --Ultrasound, CT, and MR have all been used extensively for HCC surveillance in patients with cirrhosis. On MR, HCC has: Intermediate to high signal intensity on T2-weighted images. Variable intensity on T1-weighted images. Hyperintensity on diffusion-weighted imaging (DWI): helps to detect small lesions. Often a surrounding capsule, better seen with larger HCCs. It is typically thin and discontinuous, hypointense to liver on both T1 and T2-weighted images. On contrast-enhanced CT and MR, most HCC: Are hypervascular compared to the surrounding parenchyma during the arterial phase (sensitivity varies from 58% to 88%). Become hypodense on portal-venous or delayed phase "washout" (sensitivity of 64%). The capsule, if present, shows progressive delayed enhancement. The most recent recommendations for the diagnosis of HCC state that the diagnosis is confirmed; if a mass measures more than 2 cm and shows typical features of HCC (hypervascularity in the arterial phase and washout in the early or delayed venous phase) at contrast-enhanced CT or MRI, or if a mass measuring 1-2 cm shows these features on both modalities. Some particular findings: Well differentiated HCC: may not be hypervascular on arterial-phase images; the diagnosis of malignancy can still be made if a well-defined capsule and internal washout are detected on delayed-phase images. Large HCC, often have prominent areas of neovascularity as well as central areas of necrosis. HCC may occasionally contain areas of fat which is highly suspicious for HCC. Page 22 of 55

23 HCC has a classic ability to invade liver blood vessels. Differential diagnosis: Vascular shunts, regenerative nodules, and dysplastic nodules are the more common lesions that require differentiation from HCC in patients with chronic liver disease. Vascular shunts can also be seen in the absence of cirrhosis but are much more commonly encountered in the setting of cirrhosis. They are geographically shaped, located peripherally, and isointense to liver on all unenhanced sequences. They are hypervascular on arterial phase images and become isointense to liver on delayed dynamic images. Occasionally, the configuration is more rounded, mimicking hepatocellular carcinoma. Page 23 of 55

24 Fig. 15: Cirrhosis in a 48 year old man. Enhanced T1 weighted MR arterial phase demonstrates spontaneous arterioportal shunt as a wedge-shaped region of enhancement (arrow) in the periphery of the right lobe, noted only on early arterialphase imaging. References: Radiology, La Rabta - Tunis/TN HCC in noncirrhotic liver: HCC develops in noncirrhotic liver, in less than 20% of cases. The average age of onset, is inferior to that of HHC with cirrhotic liver. Some toxic risk factors are classic but rarely involved in practice: aflatoxin B, androgen, vinyl chloride. Other factors are entangled with risk of cirrhosis: Hepatitis B and C infections. Page 24 of 55

25 obesity and diabetes, usually combined with nonalcoholic steatohepatitis (NASH) syndrome. Histological and imaging features of HHC in noncirrhotic liver do not differ from those of HHC in cirrhotic liver. Case 1: 89 year old man with post viral hepatitis B cirrhosis. Presenting right hypochondriac pain and elevation of alpha-fetoprotein. MRI was performed, showing multiple HCC lesions. Fig. 11: (a)hypointense small lesion(arrow), barely visible on unenhanced T1weighted image at segment III within heterogenous cirrhotic liver. (b) Diffusionweighted imaging (DWI): helped to detect this small lesion showing focal hyperintensity. Homogeneous enhancement of the small lesion during (c)arterial phase,becoming hypointense to liver on (d) portal phase image :washout. Page 25 of 55

26 References: Radiology, La Rabta - Tunis/TN Case 2: 65 year old woman with post viral hepatitis B. Poorly monitored. US screening showed hypoechoic nodule at segment III. Fig. 12: (a)t1-weighted axial MR image shows a solitary hypointense mass in segment III with hypointense capsule(red arrow). (b) T2-weighted fat-saturated MR image shows heteregeneous hyperintense lesion. (c) Arterial phase T1-weighted axial MR image shows heterogeneous enhancing of the mass. (d) and (e): portal and delayed-phase T1-weighted MR image reveals hypointensity(wash out) of mass with capsular enhancement(red arrow) confirming the diagnosis of HCC. References: Radiology, La Rabta - Tunis/TN Case 3: Page 26 of 55

27 66 year old man with HCC developed within morphologically normal liver. Serological investigation, revealed viral hepatitis B. Fig. 13: (a) unenhanced axial CT showing large hypodence lesion in segments IV and V(white arrow); there was a second small tumour, isodense to surrounding liver parenchyma (not shown). (b) arterial phase CT shows heterogeneous enhancement of the large lesion with presence of hypodense areas of necrosis and positive homogeneous enhancement of the small tumour (red arrow). (c) In portal venous and (d)delayed phases, both HCC lesions were again hypodense. Note hepatic hilum nodal enlargement (curve arrow). References: Radiology, La Rabta - Tunis/TN Case 4: 36 year old woman with cirrhosis of an indterminate origin. Page 27 of 55

28 Fig. 14: (a) unenhanced axial CT image, demonsrtates heteregeneous dysmorphic liver. (b) Axial enhanced CT in the arterial phase shows a heterogeneously enhancing infiltrative right and left hepatic masses with ill-defined margins(red arrows) within a cirrhotic liver. (d)enhanced CT in delayed phase shows areas of washout consistent with infiltrative hepatocellular carcinoma. (c) Axial enhanced CT in portal venous phase shows thrombus within portal vein (curve arrow). References: Radiology, La Rabta - Tunis/TN Fibrolamellar Carcinoma (FLC): Conversely to HCC, FLC is more often found in younger patients without previous liver disease and does not cause elevation of alpha-fetoprotein. FLC is made up of large polygonal eosinophilic malignant hepatocytes in lamellated bands of fibrosis. Has a better prognosis with a better resectability. Page 28 of 55

29 Imaging features: Morphologically, FLC is typically a single large tumour with well-defined and lobulated margins and dense fibrotic bands forming a central scar (seen in about 75% of cases), which make it resemble FNH. Calcifications within the scar are possible. Occasionally small peripheral satellite lesions may be present. Vascular invasion is uncommon, unlike HCC. Regional (hepatic hilum) nodal enlargement is seen in about 50% of cases. At US, FLC has mixed echogenicity. On contrast-enhanced CT and MRI, FLC is typically heterogeneously hypervascular. Enhancement on portal venous and delayed-phases images is variable. On MR conventional imaging FLC is: Hypo- to isointense on T1-weighted images. Slightly hyperintense on T2-weighted images. The central scar is low in signal on both T1- and T2-weighted images and shows minimal or no enhancement in contrast to FNH. FNH Fibrolamellar carcinoma Central scar: Hyperintense ont2 W MR Central scar: Hypointense on T2 W MR Delayed enhancement No enhancement Small Large Intracellular lipid detectable by chemical Intra cellular lipid is less commonly seen shift is more commonly seen The tumor is generally small in size Page 29 of 55

30 The tumor is larger, more lobulated and more heterogeneous Calcifications are rare Calcifications are common Case 1: 46 year old man with fibrolamellar Carcinoma. History of epigastric pain. Fig. 16: (a) T1 weighted axial MR image shows, tow lobulated hypointense masses in left liver and segments IV and V. (b) T2 weighted axial MR image shows hyperintense lesions with large hypentense fibrous scars(arrows). (c) Arterial phase MR shows enhancement of both tumors with hypointense central scars (arrows). (d) On delayed phase MR, tumors become isointense to liver; the central scar of segment V lesion shows minimal enhancement; that of left liver lesion shows no enhancement References: Radiology, La Rabta - Tunis/TN Page 30 of 55

31 Biopsy: FLC 4. Hypervascular metastasis: Metastases are the most common malignant liver lesions. They are usually multifocal. Hepatic metastases may be hypovascular or hypervascular. Most liver metastases are hypovascular. Both hypo and hypervascular metastasis are generally irregular with indistinct margin. Hypovascular Metastasis Hypervascular Metastasis Colon, lung, breast, gastric carcinomas. Primary neuroendocrine tumors (pancreatic islet cell tumor, carcinoid tumor, pheochromocytoma) Renal cell carcinoma, thyroid carcinoma, choriocarcinoma, or melanoma. On T2-weighted images: iso- to hyper- On T2-weighted intensity hyperintense. images: usually On T1-weighted images: hypo- to iso- On T1-weighted images: generally intensity. moderately hypointense exept hemorrhagic lesions (kidney, melanoma). Tend to lose signal in heavily T2 weighted May be hyper-intense on long TE T2W (TE > 160) images unlike hemangioma. images Show decreased enhancement relative to normal liver. Enhance earlier and are best seen on arterial phase images. Demonstrate Best seen on the portal-venous phase: variable degrees of washout on perilesional enhancement. delayed images; tend to wash out contrast from the periphery on delayed contrast-enhanced images showing target Page 31 of 55

32 appearance: (100% specificity) especially in neuroendocrine and carcinoid tumors. Case 1: Abdominal CT scan of a 50 year old woman with metastases of a neuroendocrine tumour of the pancreas. Fig. 17: (a) unenhanced axial CT images show, cephalic and uncinate pancreatic isodense process (white arrow) and a barely visible hypodense liver lesion in segment VII (red arrow). (b)arterial phase CT images demonstrates a blush of contrast enhancement of the pancratic tumor associated with two similarly enhanced liver lesions (red arrows). (c) and (d) portal venous and delayed phases images show progressive attenuation within a same kinetic of both pancreatic tumor and hepatic hypervascular metastasis which. They are no longer visible on delayed images. References: Radiology, La Rabta - Tunis/TN Page 32 of 55

33 5. Rare hepatic hypervascular tumors: Hepatic epithelioid hemangioendothelioma Hepatic epithelioid hemangioendothelioma is a rare neoplasm of vascular origin. EHE is an intermediate-grade malignancy, between benign hemangioma and angiosarcoma, with variable aggressiveness. Occurs at any age, most commonly in women with a sex ratio of 2:1. Some risk factors are incriminated, such as estrogens intake or exposure to chloride vinyl. There is no specific biologic marker. Often metastases to lung and bone. Involvement is often multinodular, simulating metastases from primary extra-hepatic malignancy, leading to delays in diagnosis. Imaging features: They tend to be multiple solid tumor nodules, located in a predominantly peripheral distribution, with coalescence as individual nodules, at later stages. Lesions adjacent to the capsule often produce hepatic capsular retraction. US: variable findings. CT: Typically seen as multiple hypo-attenuating nodules in both hepatic lobes that coalesce to form larger confluent hypo-attenuating regions in a peripheral or subcapsular distribution. Calcifications may be present. Early peripheral enhancement is seen since arterial phase. It is persistent on portal venous phase, resulting in halo or target pattern of enhancement especially in larger lesions. Page 33 of 55

34 MRI: T1 - hypointense lesions relative to normal liver parenchyma on unenhanced T1-weighted images T2 - heterogeneously increased signal intensity. Peripheral halo or a target-type enhancement pattern after administration of a gadolinium, with occasional observation of a thin peripheral hypointense rim. But diagnosis of HEE should be suggested in the presence of: Peripheral topography of nodules Intratumoral calcifications Capsular retraction Diagnosis is often made by histology. Case 1: Epithebioid hemangioendothelioma in a 30 year old woman with history of chest pain and fever. Page 34 of 55

35 Fig. 18: (a) Late arterial phase axial CT scan shows peripheral enhancement of coalescent large tumor nodules with central areas of necrosis (white arrows). (b) lower CT plane demonstrates capsular retraction(red arrow) and calcifications (green arrow) within the lesion. (c) multiple nodular lung metastatic lesions are seen at thoracic level(arrow). References: Radiology, La Rabta - Tunis/TN Images for this section: Page 35 of 55

36 Fig. 1: Typical FNH at ultrasound. (a) US shows a homogeneous unencapsulated lesion. (b) Color Doppler demonstrates central feeding artery.(c) Spectral analysis shows an arterial flow. Page 36 of 55

37 Fig. 2: (a)precontrast CT scan demonstrates a focal hypodense lesion (b)arterial phase CT demonstrating strong enhancement within the segment VI of liver. (c) Portal phase CT image shows lesion attenuation. Page 37 of 55

38 Fig. 3: (a) Precontrast T1-weighted axial MR shows hypointense lesion within the segment VI. (b) T2-weighted axial MR image shows isointense lesion. Contrast enhanced MR demonstrates strong enhancement in the arterial phase (c),followed by isointensity of the lesion during (d) the portal venous phase. Page 38 of 55

39 Fig. 4: Precontrast CT scan demonstrates a focal isodense lesion developed at segment IV of liver. Arterial phase CT demonstrating strong homogeneous enhancement of these mass. Portal phase CT image shows lesion attenuation similar to the liver. Page 39 of 55

40 Fig. 5: (a) T1-weighted axial MR shows homgeneous isointense, nonencapslated lesion at segment IV of liver with central hypointensity (arrow).(b) T2-weighted axial MR image shows homgeneous isointense lesion. Central scar is strongly hyperintense (arrow). (a-c) Pre and postcontrast T1-weighted axial MR images showing dramatic lesion enhancement on the arterial phase followed by attenuation during (d)portal and (e)delayed imaging. Note the scar enhancement on (e)delayed imaging (arrow). Page 40 of 55

41 Fig. 6: (b)t2-weighted coronal MR image shows subtle hyperintense to normal liver(curved arrow) large and well circumscribed mass(staight arrow) in the right liver. It appears isointense on (a) precontrast T1-weightedimage. The mass shows homogeneous enhancement during (c) the arterial phase; and remains slightly hyperintense on (d) portal venous phase image. Page 41 of 55

42 Fig. 7: (a) unenhanced T1-weighted axial in phase image shows multiple heterogeneous diffuse lesions within an enlarged liver. (b) out of phase T1 weighted image demonstrates that some lesions contains areas of fat: signal drop-out (arrow). (c) hyperintense lesions on T2-weighted image. (d)all lesions show strong arterial enhancement. Enhancing regions are mostly isointense to liver parenchyma in venous imaging. (e) In delayed phase, most lesions are slightly hypointense compared with surrounding liver parenchyma. Two lesions with peripheral contrast enhancement are shown in this slice (arrows). Page 42 of 55

43 Fig. 8: US shows delineated and hypoechoic nodule of the segment VI. Power Doppler shows flow signals in and around. Page 43 of 55

44 Fig. 9: (a) Axial CT scan after contrast injection in arterial phase. Hepatic hypervascular hemangioma with similar enhancement to the aorta and early enhancement of parenchyma adjacent to the lesion. (b) Axial CT scan after contrast injection in portal phase. The hepatic hemangioma has the same enhancement than that of the aorta. Page 44 of 55

45 Fig. 10: Axial T2 weighed MRI sequence. The hepatic hemangioma has an atypical T2 signal intensity (arrow) which is not as bright as cerebrospinal fluid as usually found in hepatic hemangiomas. Page 45 of 55

46 Fig. 11: (a)hypointense small lesion(arrow), barely visible on unenhanced T1-weighted image at segment III within heterogenous cirrhotic liver. (b) Diffusion-weighted imaging (DWI): helped to detect this small lesion showing focal hyperintensity. Homogeneous enhancement of the small lesion during (c)arterial phase,becoming hypointense to liver on (d) portal phase image :washout. Page 46 of 55

47 Fig. 12: (a)t1-weighted axial MR image shows a solitary hypointense mass in segment III with hypointense capsule(red arrow). (b) T2-weighted fat-saturated MR image shows heteregeneous hyperintense lesion. (c) Arterial phase T1-weighted axial MR image shows heterogeneous enhancing of the mass. (d) and (e): portal and delayedphase T1-weighted MR image reveals hypointensity(wash out) of mass with capsular enhancement(red arrow) confirming the diagnosis of HCC. Page 47 of 55

48 Fig. 13: (a) unenhanced axial CT showing large hypodence lesion in segments IV and V(white arrow); there was a second small tumour, isodense to surrounding liver parenchyma (not shown). (b) arterial phase CT shows heterogeneous enhancement of the large lesion with presence of hypodense areas of necrosis and positive homogeneous enhancement of the small tumour (red arrow). (c) In portal venous and (d)delayed phases, both HCC lesions were again hypodense. Note hepatic hilum nodal enlargement (curve arrow). Page 48 of 55

49 Fig. 14: (a) unenhanced axial CT image, demonsrtates heteregeneous dysmorphic liver. (b) Axial enhanced CT in the arterial phase shows a heterogeneously enhancing infiltrative right and left hepatic masses with ill-defined margins(red arrows) within a cirrhotic liver. (d)enhanced CT in delayed phase shows areas of washout consistent with infiltrative hepatocellular carcinoma. (c) Axial enhanced CT in portal venous phase shows thrombus within portal vein (curve arrow). Page 49 of 55

50 Fig. 15: Cirrhosis in a 48 year old man. Enhanced T1 weighted MR arterial phase demonstrates spontaneous arterioportal shunt as a wedge-shaped region of enhancement (arrow) in the periphery of the right lobe, noted only on early arterial-phase imaging. Page 50 of 55

51 Fig. 16: (a) T1 weighted axial MR image shows, tow lobulated hypointense masses in left liver and segments IV and V. (b) T2 weighted axial MR image shows hyperintense lesions with large hypentense fibrous scars(arrows). (c) Arterial phase MR shows enhancement of both tumors with hypointense central scars (arrows). (d) On delayed phase MR, tumors become isointense to liver; the central scar of segment V lesion shows minimal enhancement; that of left liver lesion shows no enhancement Page 51 of 55

52 Fig. 17: (a) unenhanced axial CT images show, cephalic and uncinate pancreatic isodense process (white arrow) and a barely visible hypodense liver lesion in segment VII (red arrow). (b)arterial phase CT images demonstrates a blush of contrast enhancement of the pancratic tumor associated with two similarly enhanced liver lesions (red arrows). (c) and (d) portal venous and delayed phases images show progressive attenuation within a same kinetic of both pancreatic tumor and hepatic hypervascular metastasis which. They are no longer visible on delayed images. Page 52 of 55

53 Fig. 18: (a) Late arterial phase axial CT scan shows peripheral enhancement of coalescent large tumor nodules with central areas of necrosis (white arrows). (b) lower CT plane demonstrates capsular retraction(red arrow) and calcifications (green arrow) within the lesion. (c) multiple nodular lung metastatic lesions are seen at thoracic level(arrow). Page 53 of 55

54 Conclusion Liver masses can be classified into hyper and hypo-vascular masses based on the degree of their arterial supply. If the liver is normal, the most common cause of hypervascular lesions is hypervascular hemangioma. In the presence of cirrhosis, the likely cause is HCC. MRI is the modality of choice in the tissular characterization which remains difficult in some cases, pointing to the use of histology. Personal information References 1. Askri A, Mannai S, Landolsi S, Ben Farhat L, Said W, Dali N, et al. Hémangioendothéliome épithélioïde hépatique: à propos de 3 cas. J Radiol. 2009;90(3):310#4. 2. Alkofer B, Lepennec V, Chiche L. Hepatocellular cancer in the non-cirrhotic liver. J Visc Surg. févr 2011;148(1):3# Baranes L, Chiaradia M, Pigneur F, Decaens T, Djabbari M, Zegaï B, et al. Imaging benign hepatocellular tumors: Atypical forms and diagnostic traps. Diagn Interv Imaging. juill 2013;94(7-8):677# Chiche L, Dao T, Salamé E, Galais MP, Bouvard N, Schmutz G, et al. Liver adenomatosis: reappraisal, diagnosis, and surgical management: eight new cases and review of the literature. Ann Surg. 2000;231(1): Chung J, Yu J-S, Kim DJ, Chung J-J, Kim JH, Kim KW. Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI. Magn Reson Imaging. nov 2011;29(9):1235# Kamaya A, Maturen KE, Tye GA, Liu YI, Parti NN, Desser TS. Hypervascular Liver Lesions. Semin Ultrasound CT MRI. oct 2009;30(5):387# Khan MR, Saleem T, Ul Haq T, Aftab K. Atypical focal nodular hyperplasia of the liver. Hepatobiliary Pancreat Dis Int. 2011;10(1):104#6. 8. Khosa F, Khan AN, Eisenberg RL. Hypervascular Liver Lesions on MRI. Am J Roentgenol. août 2011;197(2):W204#W220. Page 54 of 55

55 9. Namasivayam S, Salman K, Mittal PK, Martin D, Small WC. Hypervascular Hepatic Focal Lesions: Spectrum of Imaging Features. Curr Probl Diagn Radiol. mai 2007;36(3):107# Nouira K, Allani R, Bougamra I, Bouzaidi K, Azaiez O, Mizouni H, et al. Atypical small hemangiomas of the liver: hypervascular hemangiomas. Int J Biomed Sci IJBS. 2007;3(4): Skarupa DJ, Ellison EC, Vitellas KM, Frankel WL. Hepatocellular adenomatosis is a rare entity that may mimic other hepatocellular lesions. Ann Diagn Pathol. févr 2004;8(1):43# Familiar adenomatosis &1 liver factor inactivation.pdf. Page 55 of 55