Multimodality imaging of gallbladder disorders with histological correlation

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1 Multimodality imaging of gallbladder disorders with histological correlation Poster No.: C-2305 Congress: ECR 2012 Type: Educational Exhibit Authors: M. De La Hoz Polo, M. Paraira, S. Pasetto, A. Pedrerol, M san martin, J. A. DE MARCOS ; Terrassa/ES, Barcelona/ES, 3 4 Barcelona, 08/ES, TERRASSA/ES Keywords: Edema, Education, Ultrasound, MR, CT, Abdomen DOI: /ecr2012/C-2305 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 41

2 Learning objectives To illustrate the radiological signs of diverse conditions that affect the gallbladder with histological correlation Background The gallbladder serves as the repository for bile produced in liver. May be the seat of a variety of multiple diseases. Most processes are primary and rarely it is a site of secondary involvement. Acute cholecystitis is the most frequent pathology, but the gallbladder may be affected by chronic diseases such as chronic and xanthogranulomatous cholecystitis. Other entities are adenomyomatosis and polyps. It may also be affected by a primary neoplasm, and rarely by metastases. Imaging findings OR Procedure details We reviewed the cases of gallbladder disease explored in our department in the last two years. Despite ultrasound (US) is tipically the initial imaging modality approach to the patient with billiary disorders due to its high sensitivity and specificity and its wide availability, the gallbladder can be also evaluated with magnetic resonance imaging (MRI) and computed tomography (CT). We describe the different processes in the following groups: 1. Acute inflammatory pathology 2. Chronic inflammatory pathology 3. Benign entities 4. Malignant tumors Page 2 of 41

3 1 ACUTE INFLAMMATORY PATHOLOGY: Calculous acute cholecystitis (90-95%): Due to gallstone impaction in the gallbladder neck or cystic duct. Gallstones might have a different appearance depending on the imaging technique used for their study: At US, stones are normally seen as mobile echogenic foci casting posterior acoustic shadows.sometimes a wall-echoshadow sign (WES) is observed if the gallbladder is filled with gallstones. Fig. 1 on page 9 At CT gallstones may appear hyper, iso, or hypoattenuating. Nitrogen gas accumulation within gallstone fissures is sometimes observed as air density within the stone ("Mercedes Benz sign") Fig. 2 on page 10 At MRI stones usually appears hypointense at T2-WI, (signal void)fig. 3 on page 11 and hyper or hypointense at T1-WI, depending on their composition.fig. 4 on page 12 US: Fig. 5 on page 13 Laminated gallbladder wall thickening (>3mm) Gallstones (95%) Hyperemia of the gallbladder wall at Doppler imaging Fig. 11 on page 17 Hydropic dilatation of the gallbladder ( > 5 x10cm) Positive sonographic Murphy sing (pain elicited by pressure over the sonographically located gallbladder) Pericholecystic and perihepatic fluid Fig. 6 on page 13 Homogeneous wall enhancement after intravenous contrast media administration Fig. 7 on page 14 The presence of gallstones and sonographic Murphy sign has a postive predictive value for acute cholecystitis of 92% The positive predicted value for acute cholecystitis is 95% when there is the conjunction of gallstones and gallbladder wall thickening CT :Fig. 8 on page 14 Pericholecystic inflammatory fat stranding Pericholecystic and perihepatic fluid Hypo- or hyperattenuating gallstones Edematous hyperattenuation of the gallbladder fossa with contrast enhanced CT (transient hepatic attenuation) Fig. 9 on page 15 CT is particularly useful for evaluating the many complications of acute cholecystitis (emphysematous and gangrenous cholecystitis, hemorrhage, and gallstone ileus..) MRI: Fig. 10 on page 16 Page 3 of 41

4 At T2-WI: Hyperintensity and thickening (>3mm) of the gallbladder wall. Pericholecystic fluid and edema of the adjacent fat. At T1-WI: A marked hypointense bile. Increased enhancement of the gallbladder wall and surrounding liver parenchyma with gadolinium administration (70%), a highly specific sign Acalculous acute cholecystitis (5-10%) Fig. 6 on page 13 Fig. 11 on page 17: Critically ill patients US, CT and MRI: Similar findings to those seen in calculous acute cholecystitis Absence of cholelithiasis Usually sludge in the gallbladder lumen Complications of Acute Cholecystitis: Gangrenous Cholecystitis (2-38%) Fig. 13 on page 18 Fig. 14 on page 18: Increased intraluminal pressure may produce gallbladder wall ischemia and necrosis and consequently perforation. US: Asymmetric gallbladder wall thickening Striation of the gallbladder wall (40%) Intraluminal membranes A negative sonographic Murphy sign (66%) Echogenic shadowing foci consistent with gas within the gallbladder wall or lumen Fig. 17 on page 21 Disruption of the gallbladder wall Pericholecystic abscess CT: Gas in the wall or lumen Fig. 16 on page 20 Fig. 17 on page 21 Intraluminal membranes Lack of gallbladder wall enhancement (focal or difuse) Irregular or absent wall Pericholecystic abscess MRI: Hyperintense areas within or adjacent to the gallbladder wall on fat suppresed T1 and T2-WI. Lack of gallbladder wall enhancement Pericholecystic fluid collections Emphysematous CholecystitisFig. 16 on page 20 Fig. 17 on page 21 Page 4 of 41

5 Due to the presence of gas-forming bateria in the gallbladder wall and lumen 40% of patients are diabetic Elevated risk of gangrene and perforation US: Nondependent hyperecoic focus with ring-down or comet-tail artifact Intraluminal gas appears as arclike echogenic interface with posterior reverberation artifact It should be distinguished from calcification in the wall CT: Gas withih the gallbladder wall or lumen MRI: Air in the gallbladder wall or lumen are observed as signal voids Gallbladder perforation (2-11%) : Fig. 13 on page 18 Most commonly in the fundus There are 3 subtypes: free spillage into the peritoneal cavity, contained by and adjacent abscess, and formation of a cholecystoenteric fistula US, CT and MRI: Gallbladder wall focal defect Pericholecystic fluid Gallbladder collapsed lumen Pericholecystic abscess Extraluminal gallstone Hemorragic cholecystitis Fig. 18 on page 21: US: Echogenic or heterogeneus material within the gallbladder lumen CT: High-atenuation density within the gallbladder lumen MRI: In acute phase the gallbladder content has a high attenuation on T1-WI and low attenuation on T2-WI In a subacute stage the gallbladder content is hyperintense in both T1-WI and T2-WI 2 CHRONIC INFLAMMATORY PATHOLOGY: Chronic cholecystitisfig. 19 on page 22 Fig. 20 on page 22 Fig. 21 on page 23: US, CT: Non-layered gallbladder wall thickening Gallstones Page 5 of 41

6 Most commonly the gallbladder is contracted, althought it can appear distentended Absence of pericholecystic immflamation MRI: Similars findings to those seen in US and CT With intravenous contrast administration, the gallbladder wall enhances less intensely than in acute cholecystits. The wall enhancement is smooth, slow and prolonged Porcelain gallbladder:fig. 23 on page 25 Uncomon manifestation of chronic cholecystitc It is produced by mural calcification May involve all of part of the gallbladder wall Risck factor for gallbladder carcinoma US: Echogenic curvilinear structure with acoustic shadowing Echogenic foci with acoustic shadowing in the gallbladder wall CT: Plaques or punctate foci of mural calcification Xanthogranulomatous cholecystitis (XGC):Fig. 25 on page 26 Uncommon variant of chronic cholecystitis Increased risck for gallbladdder carcinoma US:Fig. 24 on page 26 Cholelithiasis Marked asymetric gallbladder wall thickening Intramural hypoechoic nodules or bands CT: Diffuse or focal galbblader wall thickening Heterogeneous wall enhancement Hypoattenating mural nodules CT findings that help discrimante between gallbladder carcinoma and XGC: a.)low-attenuation intramural nodules occupying more than 60%of the thickened wall b.)countinuos linear enhancement of the mucosa MR: Intramural nodules with markedly hyperintense signal intensity on T2-WI Preservation of linear mucosal enhancement with iv gadolinium adminstration 3 BENING ENTITIES: Page 6 of 41

7 Cholesterol polyps: Single or multiple Typically 5-10mm US:Fig. 27 on page 28 Echogenic nodules attached to the gallbladder wall No posterior acoustic shadowing CT:Fig. 28 on page 29 Can be detected on enhanced-ct because of vascularity of the polyp MR:Fig. 29 on page 29 Intermediate to low signal intensity on T2-WI Adenomyomatous hyperplasia:fig. 30 on page 30 Gallstones coexistent in 90% Three variants: localized (fundal), segmental or diffuse US: Focal or diffuse gallbladder wall thickening Localized form manifests as crescentic solid mas in th fundus Segmental form typically involves the mid portion of the body giving it an hourglass configuration Multiple intramural echogenic foci with "comet tail" reverberation artifacts Fig. 31 on page 30 CT: Focal or diffuse wall thickening Mass in the fundus Brisk enhancement of the wall after iv contrast administration MR:Fig. 32 on page 31 "String of beads sign":high-signal intensity foci on T2-WI in the thickened wall Sympathetic thickening of the gallbladder wall:fig. 34 on page 32 Possible causes are: -Hepatic dysfunction (hepatitis, cirrhosis), most common -Acute inflmmatory process in the rigth upper quadrant -Systemic conditions (heart failure, renal insuficency) These entites may mimic the presentation of acute cholecystitis The tenderness is often remote to the sonographycally located gallbladder US Fig. 35 on page 33 Fig. 36 on page 34 : Markedly laminated and thickened wall "onion peel" Lack of tense gallbladder distension Gallstones may or may not be present After iv administration of sonographic contrast media we have observed mucosal enhancement only Endometrial implants: Page 7 of 41

8 Rarely MR: T1-WI and T2-WI will demonstrate the presence of blood products Variable enhancement 4 MALIGNANT TUMORS Gallbladder Carcinoma: Predisposing risk factors: cholelithiasis, chronic biliary infection, primary sclerosing cholangitis and porcelain gallbladder Aproximately 2% are diagnosed incidentally at histopathology May appear as: Mass ocupying the gallbladder lumen(40-65%): Fig. 37 on page 35 Fig. 38 on page 35 US: Heterogeneous, hypoechoic tumor with ill-defined margins Anechoic foci: trapped bile or necrotic tumor Echogenic shadowing foci: gallstones, porcelain gallbladder Contrast enhanced-us: we have seen a rapid enhancement in arterial phase followed by rapidly washout CT: Calcification of gallbladder wall and gallstones Ill-defined hipovascular mass ocupying the gallbladder fossa Enlarged portal lymph nodes Enhanced-CT:-intense irregular enhancement at the periphery in the arterial phase with persistent enhancing tumor in portal and delayed phase MR: T1-WI: Hypo-to-iso intense gallbladder fossa mass T2-WI: Sligthly hyperintense mass Signal-voids because calcifications Contrast enhanced-mr: same findings as those seen with enhanced CT Focal or diffuse gallbladder thickening(20-30%): Fig. 40 on page 37 Fig. 41 on page 38 US, CT, MR: Asymetric gallbladder thickening > 1cm Enhancement after intravenous contrast media administration Gallstones Intraluminal polyp (15-25%): US, CT, MR: Page 8 of 41

9 Nodular mass >1cm in diametre May have thickened implantation base Gallbladder Metastasis: Malignant melanoma is the commonest cause (50%). Other primary neoplasm:lung, esophagus, pancreas and colon US: Solitary or multiple hyperecogenic masses attached to gallbladder wall >1cm MR: Masses show high- signal intensity on T1-WI and T2-WI Lymphoma: Extremely rare Primary: non-hodgkin lymphoma (MALT) Secondary to systemic disease At imaging is difficult to diffenciate from gallbladder carcinoma MR: Gallbladder wall thickening Ill-defined hyperintense on T2-WI and hypointense on T1-WI mass in the gallbladder fossa Extension into the liver Lymph nodes Images for this section: Page 9 of 41

10 Fig. 1: US.A) Gallstones seen as echogenic foci casting posterior acoustic shadow.b) Sometimes a wall-echo-shadow sign is observed if the gallbladder is filled with gallstones Page 10 of 41

11 Fig. 2: CT. Nitrogen gas accumulation within gallstones is seen as air density within the stones Page 11 of 41

12 Fig. 3: A) Axial T2-WI MR image reveals stones appearing as multiple signal-voids within the hyperintense bile. B) Coronal MR cholangiogram shows a gallbladder filled with stones. Also a stone in the distal choledoc is noted Page 12 of 41

13 Fig. 4: Pigmented gallstone. MR T1-WI and T2-WI reveal a high-intensity stone on T1WI. On T2-WI, both pigmented and cholesterol gallstones are shown as signal-void. Fig. 5: Calculous acute cholecystitis. Longitudinal sonogram shows distended gallbladder, wall thickening and a gallstone Page 13 of 41

14 Fig. 6: Acute acalculous cholecystitis.a) Longitudinal sonogram depicts laminated appearance of thickened gallbladder wall with hypoechoic region between echogenic lines consistent with edema. B) Transversal US shows pericholecyistic fluid at the gallbladder fundus. Fig. 7: US. Acute cholecystitis A,B)Laminated gallbladder wall thickening. C)Contrast enhanced US (Sonovue): With administration of intravenous contrast, the thickened gallbaldder wall shows an homogeneus enhancement Page 14 of 41

15 Fig. 8: CT. A,B) An obstructing gallstone is noted at the infundibulum (white arrow). Pericholecystic fat stranding (curved arrow). Page 15 of 41

16 Fig. 9: Contrast enhanced CT. Acute Cholecystitis. Noted the increased enhancement of the surrounding liver parenchyma (Transient hepatic attenuation),a highly specific sign for acute cholecystitis. Page 16 of 41

17 Fig. 10: Acute cholecystitis.axial and coronal MR T2-WI. A,B) The thickened gallbladder wall is hyperintense and ill-defined. There is pericholecystic and perihepatic fluid (white arrows). Hyperintensity of the adjacent fat is also seen. C) Gallbladdder sludge is shown as hypointense material within the gallbladder lumen Fig. 11: US. Acalculous Acute Cholecystitis. A) Noted the hyperemia of the gallbladder wall at Doppler imaging.b,c) Laminated gallbladder wall thickening (>3mm), hydropic dilatation of the gallbladder (>5cm in the transversal plane) with the lumen filled with tumefactive sludge. Page 17 of 41

18 Fig. 12: Acute cholecystitis showing polymorhonuclear infiltrate. (HE, 40x) ulceration, hemorrhage, edema and Fig. 13: CT, US and MRI. Gangrenous acute cholecystitis with perforation in a 57 years old man. The gallbladder showed distention and a stone, smooth stranding of the fat adjacent to the gallbladder( red arrow), and lack of gallbladder wall enhancement. MR T2-WI and US performed the day after, showed a complicated cholecystitis with perforation(black arrow) and an adjacent abscess(curved arrow) Page 18 of 41

19 Fig. 14: Gangrenous cholecystitis. Contrast enhanced-ct. The image shows gallbladder distention, wall thickening, stranding of the surrounding fat, and lack of enhancement of the mucosa at gallbladder fundus. Page 19 of 41

20 Fig. 15: Gangrenous cholecystits. Photomicrograph (original magnification, 40; HE stain) shows sloughed mucosa and a split muscular layer (arrows) with hemorrhage and extensive acute inflammatory cell infiltrations Page 20 of 41

21 Fig. 16: Contrast enhanced CT images show gas( red arrows) in the wall and lumen of the gallbladder in a patient with Emphysematous cholecystitis Fig. 17: Ultrasound, CT,and MRI in 80-year-old man with emphysematous cholecystitis. A)US image shows non-dependent arc-like echogenic line (thick arrow) with reverberation artifact (thin arrows)suggesting the presence of air.b)ct image shows air in the anterior portion of gallbladder lumen(red arrow), pericholecystic fat stranding, and gallbladder wall thickening, consistent with emphysematous cholecystitis. C)T2-WI. Signal void is noted anteriorly within lumen of gallbladder (green arrow),suggestive of air. Page 21 of 41

22 Fig. 18: Hemorraghic Cholecystitis.60-year-old man on oral anticoagulant therapy. Broadcourt showed an INR of 3.8. A) US shows distended gallbladder filled with markedly echogenic material resembling sludge. B) Note lack of signal in colour Doppler sonography. C) Contrast enhanced CT shows hyperattenuating material within the gallbladder lumen consistent with intraluminal hemorraghe. Fig. 19: Axial A) and coronal B) contrast enhanced CT images show contracted gallbladder with thickened wall. Calcifications are seen as punctuate foci in dependent portion of the gallbladder ( arrow). C) MR T2-WI image shows nondistended gallbladder with thickened wall of low signal intensity. Sluge within the gallbladder lumen is seen as hypointense material Page 22 of 41

23 Fig. 20: 62 year-old female with fever and right upper quadrant tenderness. Contrastenhanced axial CT depicts moderately distended gallbladder, non-thickened gallblader wall, big gallstone (red arrow), hyperenhancement of adjacent hepatic tissue (blue arrows), and pericholecystic fat stranding (white arrow), consistent with acute calculous cholecystitis on a chronic cholecystitis Page 23 of 41

24 Fig. 21: Chronic cholecystitis. A)US, B)Contrast enhanced CT, C)MR T2-WI, show nondistended gallbladder with non-laminated wall thickening.a)us. Gallstones with posterior acoustic shadowing are also seen. B)Contrast enhanced CT. There is no enhancement of pericholecystic hepatic parenchyma, and also note absence of pericholecystic fat stranding.c) T2-WI:There is no hyperintensity of pericholecystic tissues. Page 24 of 41

25 Fig. 22: Chronic colecistitis and Rokitnsky-Aschoff sinus associated with hyperplasia of the muscle wall. (HE, 40x) Page 25 of 41

26 Fig. 23: Porcelain gallbladder. A,B)US and non-contrast enhanced CT images showing mural calcifications in the gallbladder wall. Fig. 24: 71 year-old man with Xanthogranulomatous cholecystitis. Transverse sonogram of gallbladder shows marked wall thickening with intramural hypoechoic nodules (arrowhead) and intraluminal stone(arrow). Page 26 of 41

27 Fig. 25: 80 year-old male with right-upper quadrant discomfort. US (not shown)depicted a complex gallbladdder mass suspicios for gallbladder carcinoma. The final diagnosis was XANTHOGRANULOMATOUS CHOLECYSTITIS. A) and B). Contrast-enhanced CT scans show deformed and thickened gallbladder wall containing hypoattenuating nodules (arrows) representing abscesses or foci of inflammation. Continuous enhancement of the gallbladder mucosa is seen. C)Gadolinium-enhanced T1-WI MR shows diffuse wall thickening with a non-enhanced mass within the wall and continuos mucosal enhancement. D)Coronal HASTE-WI MR shows focal high T2 signal intensity within the wall of the gallbladder (arrow), a finding that is consistent with an intramural collection. Small gallstones are seen as signal-voids. Page 27 of 41

28 Fig. 26: Xanthogranulomatous cholecystitis, diffuse or nodular collections of macrophages containing neutral fat and lipofuscin pigment. (HE, 40X) Page 28 of 41

29 Fig. 27: US. A) Cholesterol polyp. Sonogram shows echogenic less than 5mm nodule without posterior acoustic shadowing. The nodule did not move with the change of patient's position(b). Fig. 28: Colesterolosis. A,B)US. Multiple brightly echogenic nodules attached to the thickened gallbladder wall without posterior acoustic shadowing. C) Enhanced-CT shows a nodular lesion that appears to be floating within the lumen of the gallbladder because the thin stalk is not seen. Page 29 of 41

30 Fig. 29: Thick-slab T2-WI MR-cholangiopancreatogram shows small intraluminal polypoid mass consistent with colestrol polyp Fig. 30: US(A,B) and Contrast enhanced-ct(c). Segmental or annular adenomyomatosis appears as limited circumferential gallbladder wall thickening with luminal narrowing, typically within the gallbladder body, producing a characteristic hourglass configuration Page 30 of 41

31 Fig. 31: A,B)US. Adenomyomatosis. Transversal and Longitudinal sonogram depict multiple intramural high amplitude echoes attached to gallbladder wall, with "comet tail" reverberation artifacts.the differential diagnosis is with the presence of mural or intaluminal air (emphysematous cholecystitis) Page 31 of 41

32 Fig. 32: Adenomyomatosis in a 58-year-old female. MR-Cholangiography was performed to evaluate thickening of the gallbladder fundus that was seen at US (not shown). Axial T2-WI shows focal thickening of the gallbladder wall in the fundus (arrow), with small hyperintense foci "string of beads sign" representing dilated Rokitansky-Aschoff sinuses. Fig. 33: Photomicrograph (original magnification x20; HE stain) shows branching duct or gland-like structures in the wall and hyperplasia of the smooth muscle (black arrows) Page 32 of 41

33 Fig. 34: Sympathetic gallbladder wall thickening. A).54 years-old woman with cirrhosis. Longitudinal US depicts a thickened wall and free fuid (blue arrow). The "sonographic Murphy's sign" was negative. Note also heterogenicity of liver echotexture (red arrow).b) Patient with sepsis of urinari origin. Sagital US of the gallbladder demonstrates layered wall tickening with an "onion peel" image. Note lack of distention of gallbladder lumen. Page 33 of 41

34 Fig. 35: 28 years old male patient with B hepatitis. A,B) Longitudinal sonogram shows non-distended gallbladder with markedly diffuse and multilayered thickened wall ("onion peel"). B) US before intravenous contrast administration. Page 34 of 41

35 Fig. 36: Same patient as Fig 27. A) Longitudinal sonogram shows non-distended gallbladder with markedly, diffuse and multilayered thickened wall ("onion peel") B)Contrast enhanced -US shows mucosal enhancement only. Fig. 37: Gallbladder Carcinoma. A)Contrast-enhanced CT scan depicts discontinuous mucosal enhancement with locally infiltrating mass in adjacent liver. Note a calcified big gallstone in the gallbladder lumen. B)Axial and C)Coronal T2-WI show an ill-defined infiltrating mass with a signal intensity higher than that of the adjacent liver. A stone is present within the gallbladder lumen Page 35 of 41

36 Fig. 38: Sluge vs neoplasm. 50-year-old female with right upper quadrant pain. Grayscale sonogram of lumen of gallbladder appears echogenic owing to tumefactive sludge. Color Doppler sonogram shows color comet-tail artifact from sludge. It is important to recognize this artifact to avoid confusion with flow in gallbladder mass. Page 36 of 41

37 Fig. 39: Adenocarcinoma well differentiated from gallbladder, well-formed glands whith atypia involving mucosa and submucosa. (HE, 20x) Page 37 of 41

38 Fig. 40: 62 years-old male with chronic hepatitis C. Gallbladder Carcinoma. A) Initial longitudinal US shows gallstones and hyperechogenic material diagnosed as tumefactive sludge. B) 6 months later, longitudinal sonogram depicts gallstone embebed in an echogenic soft tissue mass within gallbladder lumen. There is also an extraluminal component (markers) invading adjacent hepatic tissue. Page 38 of 41

39 Fig. 41: Same patient as fig. Contrast enhanced US. A,B) Arterial phase. C,D) Portal phase. The infiltrating component shows rapidly enhancement in arterial phase and deenhancement in portal phase Page 39 of 41

40 Conclusion US, CT and MR play an important role in the evaluation of suspected gallbladder disease. However, there is some overlap between the imaging findings of the different entities that can affect the gallbladder. Hence, for a definite diagnosis, it is not only important to have a deep knowledge of the imaging findings of every one of these entities on the different techniques, but also their correlation with the patient's symptomatology. In some cases only histological diagnosis is possible. Personal Information References 1) Angela D. Levy,Linda A. Murakata, Robert M. Abbott, Charles A. Rohrmann. Benign Tumors and Tumorlike Lesions of the Gallbladder and Extrahepatic Bile Ducts: Radiologic-Pathologic Correlation. RadioGraphics 2002;22: ) Onofrio A. Catalano, Dushyant V. Sahani, Sanjeeva P. Kalva. MR Imaging of the Gallbladder: A Pictorial Essay. RadioGraphics 2008;28: ) Anthony E. Hanbidge, Philip M. Buckler, Martin E. O'Malley. Imaging Evaluation for Acute Pain in the Right Upper Quadrant. RadioGraphics 2004; 24: ) Owen J. O'Connor, Michael M. Maher. Imaging of Cholecystitis. AJR2011;196:w367w374. 5) Adriaan C. van Breda Vriesman, Marc R. Engelbrecht, Robin H. M. Smithuis. Diffuse Gallbladder Wall Thickening: Differential Diagnosis. AJR2007;188: ) Gregory A. Bortoff, Michael Y. Chen, David J. Ott. Gallbladder Stones: Imaging and Intervention. Radiographics 2000; 20: Page 40 of 41

41 7)Jung S.E., Lee J.M., Lee K., Rha S.E., Choi B.G., Kim E.K., Hahn S.T. Gallbladder wall thickening:mr imaging and pathologic correlation with emphasis on layered pattern. Eur Radiol (2005) 15: )Diagnostic Imaging. Abdomen. Michael P. Federle..et al. Amirsys. 9)Alessandro Furlan, James V. Ferris, Keyanoosh Hosseinzadeh, Amir A. Borhani. Gallbladder Carcinoma Update:Mutimodality Imaging Evaluation, Staging and Treatment Options. AJR 2008;191: Page 41 of 41