7 Imging of the Biliry Tree nd Gllldder Diseses CONTENTS 7.1 Introduction - Imging Technique 7.2 Antomy 7.2.1 Norml Antomy 7.2.2 Biliry Tree nd Gllldder Anomlies 7.3 Benign Biliry Neoplsms 7.3.1 Biliry Cystdenom 7.3.2 Bile Duct Adenom 7.3.3 Biliry Hmrtom 7.3.4 Biliry Ppillomtosis 7.4 Mlignnt Biliry Neoplsms 7.4.1 Cholngiocellulr Crcinom 7.4.2 Biliry Cystdenocrcinom 7.5 Benign Neoplsms of the Gllldder 7.5.1 Gllldder Adenom 7.6 Mlignnt Neoplsms of the Gllldder 7.6.1 Gllldder Crcinom 7.6.2 Gllldder Crcinoid 7.1 Introduction - Imging Technique The imging techniques employed to evlute the iliry system re usully selected on the sis of the dignostic informtion required, the clinicl presenttion, nd the ody hitus. Although ultrsound (US) nd computed tomogrphy (CT) re the primry non-invsive imging modlities for screening ptients with iliry tree pthology, MR cholngiopncretogrphy (MRC) is rpidly ssuming more importnt role in non-invsive evlution of the intr- nd extrheptic ile ducts. Percutneous trnsheptic cholngiogrphy (PTC) nd endoscopic retrogrde cholngiopncretogrphy (ERCP) re le to provide detiled informtion on ductl ntomy nd pthology through direct opcifiction of the ile ducts [72]. These techniques re lso very useful s non-surgicl therpeutic methods for iliry dringe, stent plcement, stone removl nd stricture dilttion. US is generlly used to screen ptients with suspected iliry ductl disese. It is usully performed using the highest-frequency trnsducer t 3.5 MHz in oese ptients nd 5 MHz in thin ptients. However, wheres the choledochl nd common heptic ducts cn usully e seen, the intrheptic ducts re rrely seen unless they re dilted. Usully the common heptic duct nd the common iliry duct re evluted using prsgittl scns nd pper s tuulr hypoechoic structures. The common heptic duct is identified nteriorly nd lterlly to the proximl min portl vein or the undivided right portl vein. The right heptic rtery psses etween the posteriorly locted portl vein nd the nteriorly locted common heptic duct which cn usully e mesured t this level. The common ile duct is difficult to evlute in the distl portion ecuse of overlying gs in the duodenum nd heptic flexure. However, visuliztion cn e improved y scnning the ptient in semi-erect position [67]. Color Doppler US is very helpful in distinguishing ile ducts from smll heptic vessels, especilly in the left loe where prllel rnching heptic nterior nd portl veins my mimic dilted left intrheptic ducts. Frequently, US is le to visulize not only the dilted ducts in ptients with iliry ostruction, ut lso the lesion ssocited with the duct dilttion. Biliry dilttion my lso e oserved in the sence of ostruction in ptients who hve undergone prior iliry surgery nd cholecystectomy, or in sujects with resolved ostruction [54]. Wheres most dominl US exmintions re performed fter prolonged fsting, the dministrtion of ftty mel prior to exmintion of the il-
238 MRI of the Liver iry tree is n djunctive mneuver tht provides functionl informtion in ddition to incresing the ccurcy of ostruction detection. Wheres norml, non-ostructed duct decreses in size or does not chnge in clier, n increse in clier of 2 mm or more suggests some degree of ductl ostruction nd the need for further evlution [58]. On CT, ile ducts pper s wter-dense tuulr rnching structures converging t the port heptis. The common heptic duct nd the common iliry ducts hve similr shpe, nd re generlly visile within the heptoduodenl ligment. The distl common iliry duct ppers on cross-section s circulr, low-density structure in the pncretic hed. The norml heptic duct on CT scns is 3-6 mm in dimeter, nd the common ile duct is 6-7 mm in dimeter. Most CT exmintions re performed in three phses (pre-contrst, rteril nd portl-venous), frequently fter the ingestion of 500-800 ml of wter to distend the gstrointestinl trct. Multi-detector computed tomogrphy (MDCT) hs gretly enhnced the cpilities of CT to ssess the upper domen, nd is incresingly proving useful for the evlution of iliry duct disese. In ddition, ecuse the totl length of the common ile duct cn e delineted more completely, MDCT my e more useful mens of precisely defining the site nd cuse of iliry ostruction. This imging modlity permits precise evlution of iliry trct normlities such s choledocholithisis, heptolithisis, cholngiocrcinom, extrinsic lesions ostructing the iliry trct, nd congenitl iliry trct nomlies [26]. MR imging (MRI) hs ecome more useful for iliry system imging since the introduction of fst imging strtegies, grdient echo sequences, fst spin-echo sequences, nd hlf-fourier cquisition single-shot sequences (HASTE). MRC in ssocition with morphologic imging using T1- nd T2-weighted sequences, hs emerged s n ccurte, non-invsive lterntive to dignostic endoscopic retrogrde cholngiogrphy (ERC) for the evlution of diseses of the iliry trct [75]. MRC is performed using hevily T2-weighted sequences tht depict the hyperintense fluid contined within the ile ducts with high signl intensity, wheres suppression of the signl of surrounding, non-fluid contining structures is chieved due to the long echo-time. MR imges re cquired in the coronl nd xil plnes, typiclly with the use of phse-rry imging coil to increse overll ccurcy [48]. MRC is usully performed using multisection technique involving the cquisition of multiple 1-3 mm thick source imges of the pncreticoiliry trct. Becuse of the orienttion of the norml ile duct, the iliry trct is usully prtilly visulized on ech of severl imges rther thn visulized in its entirety on single imge. Although dignostic decisions re usully mde on the sis of the source imges, three-dimensionl (3D) imges cn e otined with mximum intensity projection (MIP) nd multiplnr reconstruction (MPR) techniques. Moreover, 3D imges re le to provide rod mp of the ostructed ductl system, delinete complex strictures, nd ssist in the plnning of percutnous, surgicl, nd endoscopic procedures [19]. Another pproch, which ovites the need for MIP post-processing, is to employ single-shot projection technique to otin 30-70 mm thick imge, during three second cquisition. The vilility of MR contrst gents with heptoiliry properties such s Gd-BOPTA, Mn- DPDP nd Gd-EOB-DTPA, which re in prt eliminted through the heptoiliry system, permit the iliry tree to e visulized on T1-weighted imges. This pproch my prove useful for evluting lekge from the iliry tree fter heptic resection or liver trnsplnttion [21, 23]. 7.2 Antomy 7.2.1 Norml Antomy The liver is divided into the left nd right loe, nd ech loe is divided into segments on the sis of its vsculr ntomy nd iliry dringe. The intrheptic ile ducts generlly follow the internl heptic segmentl ntomy. In the left loe, left medil segment duct nd left lterl segment duct normlly join to form the min left heptic duct. The right heptic duct rnches ner its origin t the common heptic duct. Frequently, the right heptic duct hs dorso-cudl rnch, drining the posterior segment of the right loe, nd ventro-crnil rnch, drining the nterior segment of the right loe. Ductl dringe of the cudte loe is vrile nd my e relted to the left or right ductl system. The left nd right heptic ducts unite just outside the liver to form the common heptic duct, which is usully 3-4 cm in length. The common heptic duct courses ventrlly nd inferiorly with the heptic rtery nd the portl vein from the port heptis in the heptoduodenl ligment. The common heptic duct joins the cystic duct to form the common ile duct tht verges 6-7 cm in length. The common ile duct is divided into suprpncretic, intrpncretic, nd mpullry segments, nd enters the posterior-medil spect of the second portion of the duodenum through 1-2 cm long intrmurl tunnel terminting t the mjor duodenl ppill (Ppill of Vteri). The common ile duct in mny
7 Imging of the Biliry Tree nd Gllldder Diseses 239 cses joins the pncretic duct in the duodenl wll, nd hs short common chnnel. The sphincter of Oddi surrounds the common chnnel nd the choledochl sphincter surrounds the common ile duct from its entrnce into the duodenl wll to its junction with the pncretic duct. Microscopiclly, the extrheptic ducts re composed minly of elstic fiers, nd re sprse in muscle fiers. This explins their chnge in size in response to fluctutions in intrductl pressure. The gllldder is n ellipticl orgn tht strddles the intersegmentl plne etween liver segments IV nd V. The gllldder is divided into four prts: the fundus, the ody, the infundiulum, nd the neck. Usully the orgn is ttched to the liver y the prietl peritoneum. When relxed, the norml gllldder is pproximtely 10 cm long, 3-5 cm in dimeter nd hs cpcity of pproximtely 50 ml. The gllldder wll is usully 2-3 mm thick nd composed of columnr epithelium. Lymphtic dringe of the gllldder descends round the ile duct nd involves cystic nd pericholedochl lymph nodes. From the pericholedochl nodes the dringe continues to nodes found posterior to the pncres, portl vein, nd common heptic rtery, until finlly the lymphtic flow reches the lymph nodes of the interortocvl region, celic rtery, nd superior mesenteric rtery. The gllldder communictes with the common ile duct vi the cystic duct, which is 2-4 cm in length, nd contins tortuous folds known s the spirl vlves of Heister ner the neck of the gllldder. The cystic duct usully joins the common heptic duct pproximtely hlfwy etween the port heptis nd the mpull of Vteri to form the common ile duct. 7.2.2 Biliry Tree nd Gllldder Anomlies The primitive liver is composed of ipotentil emryonic cells tht cn differentite into either prenchyml or iliry cells. Biliry differentition occurs when the emryonic cells re in contct with the mesenchyme surrounding the portl vein rmifictions; this cell lyer ultimtely forms n epithelil cylinder clled the ductl plte. Some segments of the cylindricl lumen form tuulr structures tht re grdully incorported into the portl mesenchyme. This results in the portl trid cquiring tuulr ile duct surrounded y portl connective tissue. Anormlities in ductl plte development cn ffect ny level of the iliry tree, therey explining the diversity of congenitl ile duct normlities [15]. Biliry tree mlformtions, with the exception of choledocl cysts, re often symptomtic. Therefore the dignosis is frequently not mde until dulthood. 7.2.2.1 Choledochl Cyst nd Cystic Dilttion of the Bile Duct Choledochl cysts re nomlies of the iliry system chrcterized y dilttion of the extrheptic or intrheptic ile ducts. These nomlies re more frequent in femles with rtio of 4:1. In out 60% of cses the dignosis is mde in the first ten yers of life, lthough choledochl cysts my ecome evident t ny ge (see Chp. 10, MR Imging of the Liver in Peditric Ptients, section 10.3.6, Choledochl Cyst nd Cystic Dilttion of the Bile Duct ). Choledochl cysts re considered to rise s result of n nomlous junction of the pncretic duct nd common ile duct resulting in long common chnnel [28]. This ws first recognized in 1969 y Bitt [4], who suggested tht this long common chnnel llowed reflux of pncretic enzymes into the common ile duct, with susequent inflmmtion nd wekening of the common ile duct wll with progressive dilttion. Until recently, the Todni Clssifiction [64] (Fig. 1) ws used to ctegorize cystic dilttion of the iliry ducts. According to this clssifiction, type I, the most common type, comprises cystic (IA), focl segmentl (IB), nd fusiform choledochl dilttions (IC); type II cysts re true diverticul rising from the common ile duct; type III cysts, lso known s choledochoceles, re dilttions of the intrduodenl portion of the common ile duct; type IV cysts re multiple intrnd extrheptic cysts (IVA) or multiple extrheptic cysts (IVB); nd type V choledochl cysts, lso known s Croli s disese, re multifocl cystic or scculr dilted intrheptic ile ducts tht my diffusely involve the liver, or less commonly involve only the left segment of the liver. A more recent clssifiction scheme, the Miyno Clssifiction [47] (Fig. 2), now clssifies choledochl cysts ccording to n ssocition with the common chnnel. The disese is thus clssified s: 1) ssocited with the common pncretic ile duct: A (cystic), B (with intrheptic iliry tree dilttion), C (fusiform), 2) without common pncretic ile duct ssocition: D (diverticul), E (su-stenosis of the ppill with distl dilttion), F (intrheptic dilttions Croli s disese). Choledochl cysts typiclly vry from 1-10 cm, in size, lthough lrger forms exist which my contin 5-10 l of ile. Histopthologiclly, the wll is usully thickened y inflmmtion nd firosis, nd is stined with ile; islets of cylindricl or columnr epithelium nd intestinl metplsi my e present. The clssic clinicl trid of pin, mss in the right upper dominl qudrnt nd jundice oc-
240 MRI of the Liver Fig. 1. Todni Clssifiction of cystic dilttion of the iliry ducts Fig. 2. Miyno Clssifiction of cystic dilttion of the iliry ducts curs in fewer thn third of ptients with choledochl cysts. In neworns nd infnts, ostructive jundice is the most common presenttion, while in older children nd dults the signs nd symptoms re those of scending cholngitis [65]. From the surgeon s point of view, rod mpping is importnt for plnning the opertive pproch to choledochl cysts. Informtion on the nomlous rrngement of the pncreticoiliry duct system nd the morphology of the duct is extremely importnt for determining the pproprite surgicl procedure. Surgeons re concerned out the exct loction of the pncretic duct, the site of entry in the duodenum, nd the length of the common chnnel. At US these mlformtions pper s nechoic, hypoechoic fusiform or cystic lesions in the region of the port heptis, with communiction to the iliry tree (Fig. 3). The gllldder is lwys wellseprted from the cyst. Often it is possile to oserve intrluminl sludge or stones within the iliry tree. Color-Doppler US shows the sence of vsculriztion within the cyst (Fig. 4). Unfortuntely, the precise extent of cystic dilttion of the iliry system, the reltionship of the cyst to the gllldder nd pncretic duct, nd the ngle nd site of the junction with the duodenum my e difficult to ssess using US [36]. ERCP is frequently used to study the iliry tree in ptients with choledochl cysts. However, it
7 Imging of the Biliry Tree nd Gllldder Diseses 241 Fig. 3,. Choledochl cyst. US scns of choledochl cysts show n nechoic fusiform lesion (, rrowhed) nd cystic lesion (, sterisk) in the region of the liver hilum e relted to the fct tht the signl within the iliry tree is generted y the long T2 of ile. Since the T2 is shortened y protein plugs nd stones, these my e more difficult to see on MRC compred to CTC. Nevertheless, when MRC is used, 2D reconstruction ppers to e superior to 3D reconstruction for the detection of intrductl stones (Fig. 6). 7.2.2.2 Croli s Disese Fig. 4. Choledochl cyst. On Color Doppler US the choledochl cyst does not show ny vsculriztion is dignostic procedure tht demnds technicl expertise nd numer of sfety mesures, nd it is not without complictions. These include development of sepsis in n ostructed system, perfortion of the viscer pncretitis, nd overdose of contrst gent. At present, CT cholngiogrphy (CTC) nd incresingly, MRC, re effective non-invsive imging lterntives to invsive cholngiogrphy nd ERCP, prticulrly in dult ptients. MRC in prticulr ppers to offer similr informtion to ER- CP without the potentil complictions [45]. Both MRC nd CTC offer comprle performnce in estlishing dignosis of choledochl cyst in peditric ptients [36]. MRC is sed on imging of sttionry fluids on hevily T2-weighted pulse sequences. Since ile nd pncretic secretions hve high signl intensity, choledochl cysts re chrcterized y hyperintense tuulr, fusiform or cystic structure (Fig. 5). For the detection of intrductl stones CTC seems to e slightly superior to MRC. This could Croli s disese, lso known s communicting cvernous ectsi of the iliry tree, is rre congenitl disorder chrcterized y non-ostructive, scculr or fusiform dilttions of the intrheptic ile ducts. It corresponds to type V of the Todni Clssifiction nd to type F of the Miyno Clssifiction nd occurs with equl frequency in mles nd femles. Two types of the disese hve een descried: the rel, so-clled pure type, nd the more common type ssocited with congenitl heptic firosis. The less common pure form is chrcterized y scculr, digitte, or moniliform estsi of the intrheptic ile ducts, with no other histologic normlities. The normlities typiclly predominte in one segment, usully in the left loe, nd my e diffuse or loclized. The ectsis communicte freely with the ile ducts, promoting stsis nd sludge formtion, which cn led to lithisis nd cholngitis. Biliry infection nd stones ccount for the usul presenting symptoms of fever nd dominl pin. Cholngiocrcinom develops in pproximtely 5-10% of cses [46]. The more common form presents in childhood with normlities relted to heptic firosis nd portl hypertension. In contrst to congenitl heptic firosis tht rises due to the norml development of smll interloulr ile ducts, the
242 MRI of the Liver c d e f g Fig. 5-g. Choledochl cyst type IC. On hevily T2-weighted sequences (-f), the choledochl cyst ppers s fusiform, mrkedly hyperintense structure (rrowheds). The cyst shows reduction in clire (c-f) just ove the union with the Wirsung duct (rrow). 3D MR cholngiogrphy (g) shows the ductl dilttion tht involves the right heptic duct (rrowhed). Note the norml clire (rrow) elow the conjunction etween the choledochl cyst nd Wirsung duct
7 Imging of the Biliry Tree nd Gllldder Diseses 243 Fig. 6,. Choledochl cyst. 2D MR-cholngiogrphy in coronl orienttion () demonstrtes choledochl cyst nd well-defined, round, hypointense intrductl structures (rrowheds) tht correspond to stones. On 3D MR-cholngiogrphy () the numer nd size of stones (rrowhed) is less ccurtely defined more common form of Croli s disese ffects the lrge intrheptic ile ducts. Histologiclly, intrheptic ile duct ectsi nd prolifertion re ssocited with severe periportl firoses. Compred with pure Croli s disese, iliry duct dilttion is less mrked in this form nd cholngitis nd iliry stone formtion re usully sent. However severe prolems my rise due to liver filure or complictions ssocited with portl hypertension. Proposed mechnisms for ile duct mlformtion include norml growth of the developing iliry epithelium nd supporting connective tissue, nd lck of norml involution of the ductl pltes tht surround the portl trcts, resulting in epithelium-lined cysts surrounding the portl trids [34]. In the complex form, the genetic fctor tht cuses the rrest in ductl plte remodeling seems to ct not only during the erly phse of emryogenesis, ut lso lter during development of the more slender intrheptic ile ducts nd interloulr ducts. This results in the development of heptic firosis t more peripherl level of the iliry tree. Both forms of Croli s disese cn occur in comintion with kidney normlities such s infntile polycystic kidney disese nd medullry sponge kidney s well s other types of choledochl cysts. If ll levels of the iliry tree re involved, fetures of oth congenitl heptic firosis nd Croli s disese re present. This condition is often termed Croli s syndrome [34, 41, 46]. Mcroscopiclly, the intrheptic cystic dilttions re round or lnceolte, from few millimeters up to 5 cm in size, nd my e seprted y stretches of essentilly norml duct. Microscopiclly, the dilted ducts frequently show chronic inflmmtion, nd vrying degrees of firosis nd hyperplsi. Ptients typiclly suffer from outs or recurrent fever nd pin, nd jundice my occur when sludge or stones lock the common ile duct. In the pure form of Croli s disese, cholngiogrphy revels multiple communicting scculi of the intrheptic iliry tree. Stones re common nd pper s filling defects. Bile duct strictures nd wll irregulrities my occur s consequence of recurrent cholngitis. A similr ppernce my e oserved with mgnetic resonnce cholngiopncretogrphy (MRCP). On US nd CT exmintions, the scculi pper s well-defined intrheptic cystic nechoic nd hypodense res, respectively (Fig. 7, 8). Color Doppler US usully revels chrcteristic dot sign relted to the presence of portl vein rnches t the periphery of the ile duct dilttion. The presence of stones nd/or sludge my increse echogenecity nd density, nd the content my pper heterogeneous. Demonstrtion of communiction etween scculi nd the ile duct is importnt in distinguishing Croli s disese from policystic liver disese, ut this is not esy to detect when the disese is in the erly stges [46]. On MR imging, the scculi pper s homogeneously hypointense res on T1-weighted imges nd s homogeneously hyperintense res on T2- weighted imges (Fig. 9). The signl intensity is generlly homogeneous ut my pper heterogeneous if stones, sludge, or phlogistic mteril re present within the scculi nd ile ducts (Fig. 10). In this ltter sitution, the surrounding liver prenchym my lso show chnges in signl intensity [3]. MRCP is vlid tool for demonstrting
244 MRI of the Liver Fig. 8. Croli disese. On unenhnced CT, numerous hypodense lesions (rrows) with vrile shpe cn e seen in oth loes of the liver, ut predominntly in the right liver loe Fig. 7. Croli disese. On US, round nd tuulr, hypoechoic structures (rrowheds) re visile Fig. 9,. Croli disese. On pre-contrst T1-weighted GRE () nd T2-weighted TSE () imges, diffuse intrheptic round lesions (rrows), corresponding to intrheptic scculi, re homogeneously hypointense nd homogeneously hyperintense, respectively Fig. 10,. Croli disese. Pre-contrst T1-weighted GRE () nd T2-weighted TSE () imges show heterogeneity within the scculi (rrowheds) due to the presence of intrductl stones
7 Imging of the Biliry Tree nd Gllldder Diseses 245 communiction etween scculi nd ile ducts (Fig. 11), which is positively demonstrted with Gd-BOPTA nd other heptoiliry contrst gents if contrst mteril is present within the scculi nd ile ducts during the heptoiliry phse fter dministrtion (Fig. 12). Differentil dignoses of Croli s disese include primry sclerosing cholngitis, recurrent pyogenic cholngitis, nd polycystic liver disese. Primry sclerosing cholngitis nd recurrent pyogenic cholngitis my e ssocited with duct dilttion, stenosis, intrheptic clculi, nd mlignncy. The ductl dilttion in primry sclerosing cholngitis is typiclly more isolted nd fusiform thn scculr (Fig. 13), nd is not chrcteristic of Croli s disese. Recurrent pyogenic cholngitis is the most difficult dignosis to exclude ecuse ptients with pyogenic cholngitis present with sepsis nd hve intr- nd extrheptic iliry dilttion. Scculr dilttion fvors the dignosis of Croli s disese ecuse it is not typicl in recurrent pyogenic cholngitis. Heptic cysts of polycystic liver disese do not communicte with the ile ducts (see Fig. 54, Chpter 4). 7.2.2.3 Biliry Atresi Fig. 11. Croli disese on MRCP. Sme cse s demonstrted in Fig. 9. MRCP demonstrtes diffuse, hyperintense, round nd cystic lesions, distriuted in oth loes of the liver, with flower tree ppernce Biliry tresi is n olitertive cholngiopthy tht my ffect not only the extrheptic ut lso the intrheptic ile duct system, with complete olitertion or discontinuity of the heptic or common ile ducts t ny point from the port heptis to the duodenum. Ostruction of ile flow leds to cholestsis, progressive firosis, nd ultimtely, cirrhosis. The disorder occurs once every 10,000-15,000 live irths nd is more common in girls thn in oys [5]. It ccounts for pproximtely one third of ll cses of prolonged neontl cholesttic jundice (see Chpter 10, MR Imging of the Liver in Peditric Ptients, Section 10.5.2, Biliry Atresi ). Although fctors such s developmentl mlformtion, perintl viremi (cytomeglovirus, ruell, retroviruses), nd toxicity of ile constituents hve een implicted, the ctul cuse of iliry tresi remins unknown [9, 22]. A single, unifying cuse ppers unlikely, nd it seems more prole tht there is etiologic heterogeneity tht results in progressive sclerosis; for exmple, n inflmmtory process tht ffects the extrheptic iliry trct leding to ductulr luminl olitertion [5]. Biliry tresi occurs in two clinicl forms, the emryonic or fetl type, nd the perintl type. The ltter form is more frequent, nd ccounts for more thn 60% of cses. The fetl vrint my e ssocited with congenitl mlformtions such s polyspleni, crdiovsculr defects, dominl situs inversus, intestinl mlrottion, nd nomlies of the portl vein nd heptic rtery [22]. Fig. 12,. Croli disese. On the unenhnced T1-weighted GRE imge () the cystic scculi re heterogeneously hypointense. On the T1-weighted GRE imge () cquired during the heptoiliry phse fter the dministrtion of Gd-BOPTA (0.1 mmol/kg BW) the cystic scculi demonstrte n increse of signl intensity due to the presence of contrst gent within the cysts
246 MRI of the Liver c Fig. 13-c. Primry sclerosing cholngitis. T2-weighted imges (, ) show intrheptic, fusiform, hyperintense, ductl dilttion (rrows) ssocited with ductl stenosis (rrowheds). The intrheptic ductl dilttion nd stenosis re well depicted on the 3D-MRC imge (c) Biliry tresi cn e clssified in three wys ccording to the site of the ostruction: type I, ostruction t the level of the common ile duct; type II, ostruction t the level of common heptic duct; type III, ostruction t the level of the port heptis. The ltter type is considerly more frequent nd ccounts for more thn 90% of cses [9]. The mcroscopic spect of the liver vries ccording to the stge of the disese. At first it enlrges nd is drk green in color, ecoming finely nodulr s cirrhosis develops. In untreted cses cirrhosis my tke etween 1 nd 6 months fter irth to develop. Microscopiclly, cholestsis, periportl ductl prolifertion, nd the presence of ile plugs in cholngioles nd interloulr ile ducts re pprent. Firosis is progressive with periportl nd periloulr distriution. Linkge of portl res is frequent nd secondry iliry cirrhosis is possile development [5]. In iliry tresi the liver prenchym cn e norml in structure, or demonstrte signs of iliry cirrhosis with prominent heptic rtery. Signs on US tht my e relted to iliry tresi include the shpe nd contrctility of the gllldder nd the presence of the tringulr cord. In cses of iliry tresi, the gllldder hs ghostlike ppernce nd these fetures hve een descried s the gllldder ghost trid [25]. This consists of n tretic gllldder of less thn 1.9 cm in length, n sent or thinned smooth echogenic mucosl lining with indistinct wlls, nd knoly, irregulr, or loulr contour (Fig. 14). A tringulr- or tuulr-shped echogenic density on trnsverse or longitudinl scns represents firous cone t the port heptis known s the tringulr cord (Fig. 15). This focl hyperechogenicity ssocited with perivsculr hyperechogenicity is relted to progressive firosis nd ductl sclerosis, nd is very useful for the dignosis of iliry tresi (Fig. 16) [12, 32]. Although scintigrphy is not used routinely, Technetium TC 99m iminodicetic cid derivtives re rpidly excreted from the lood y heptocytes nd excreted into the owel through the iliry system. With iliry ostruction, this mteril ccumultes in the liver nd none ppers in the owel (Fig. 17). When employed for imging of infnts, phenoritl should e given for five dys efore the study. This is ecuse phenoritl increses iliruin conjugtion nd excretion nd hs choleretic effect, nd thus enhnces nd ccelertes the uptke of iminodicetic cid nlogues y the liver [17].
7 Imging of the Biliry Tree nd Gllldder Diseses 247 Fig. 14,. Biliry tresi. US scns of two different ptients with iliry tresi show different gllldder shpes. In () very smll, tretic gllldder (rrows) is pprent, while in () n enlrged gllldder (sterisk) with thinned wll is seen Fig. 15,. Biliry tresi. US scns show the tringulr cord (rrowheds) s tuulr () or tringulr () hyperechoic tissue locted t the port heptis Fig. 16,. Biliry tresi. On US B-mode () nd color Doppler US () scns, perivsculr hyperechogenicity (rrowheds) corresponding to progressive firosis is clerly seen
248 MRI of the Liver Filure of development of the cudl foregut diverticulum or filure of vcuoliztion fter the solid phse of emryonic development results in genesis of the gllldder. In out two thirds of ptients with gllldder genesis it is possile to oserve other congenitl nomlies, such s congenitl hert lesions, polyspleni, imperforte nus, sence of one or more ones, nd rectovginl fistul [66]. Ptients my e symptomtic or present with right upper dominl pin, jundice, nd vomiting. The preopertive dignosis of gllldder genesis is difficult. Wheres imging techniques such s US nd CT my suggest the dignosis, confirmtion of gllldder genesis is usully n intropertive finding, when its sence is discovered t cholngiogrphy. MR cholngiogrphy cn e considered n lterntive non-invsive imging method. The possiility of visulizing the iliry tree y mens of 3D-reconstructions nd to ssess the sence of the gllldder permits informtion to e cquired tht is similr to tht ville y intropertive cholngiogrphy. Fig. 17. Biliry tresi on scintigrphy. On Technetium 99m iminodicetic scintigrphy scns, TC 99m is progressively ccumulted in the liver nd does not pper in the owel On T2-weighted MR imging, modertely high signl intensity long the portl trct tht extends peripherlly from the port heptis correltes with periductl edem nd inflmmtory cell infiltrtion. Although iliry tresi cn e relily dignosed on the sis of the lck of visuliztion of either the common ile duct or the common heptic duct, findings on MRC should still e interpreted in reltion to clinicl informtion [22, 29, 52]. The prognosis of untreted iliry tresi is extremely poor, with deth from liver filure usully occurring within two yers. However, hepto-porto-enteronstomy cn restore ile flow in mny cses if surgery is performed sufficiently quickly fter dignosis. Additionl predictors of poor outcome re cucsin rce, the severity of the intrheptic iliry cholngiopthy, the presence of cirrhosis on initil iopsy, nd sence of ducts t the level of the liver hilus. The outcome correltes directly with the size of the ile duct remnnts identified in the port heptis t surgery. Bile duct profiles of more thn 150 mm nd lined with columnr epithelium hve een ssocited with good surgicl result [11, 24]. 7.2.2.4 Agenesis of the Gllldder 7.2.2.5 Dupliction of the Gllldder Gllldder dupliction occurs when there is excessive udding of the cudl diverticulum. It is cused y incomplete revcuoliztion of the primitive gllldder resulting in persistent longitudinl septum tht divides the gllldder lengthwise. Gllldder dupliction my lso occur due to the occurrence of seprte cystic uds. Cholecystitis with cholelithisis is reltively frequent occurrence in these ptients. The duplicted cystic ducts frequently enter the common ile duct seprtely, or lterntively, unite to form common cystic duct. Less frequently they drin independently into the heptic ducts. US is not specific for the demonstrtion of this nomly since entities such s choledochl cyst, iloed gllldder, nd gllldder diverticulum my mimic gllldder dupliction. MRC relily demonstrtes the presence of two gllldders s hyperintense scs, nd cn depict the type of dringe into the common ile duct [53]. 7.2.2.6 Anomlies of Gllldder Shpe Phrygin cp is the most common normlity of gllldder shpe. The term Phrygin cp derives from resemlnce to folded hts worn in the ncient country of Phrygi. It is chrcterized y fold or septum of the gllldder etween the ody nd fundus (Fig. 18). Although cliniclly unimportnt, it my e mistken on rdiologicl exmintion for stone or pthologicl septum. Multiseptte gllldder is chrcterized y the presence of multiple internl sept of vrious sizes
7 Imging of the Biliry Tree nd Gllldder Diseses 249 Fig. 18. Phrygin cp gllldder. On US hyperechoic septum (rrow) in the gllldder is esily visile. This corresponds to fold or septum of the gllldder etween the ody nd fundus which divide the gllldder lumen into severl chmers. Although these chmers communicte with one nother y mens of one or more orifices, these septtions my led to stsis of ile nd gllstone formtion. On US, multiple, communicting, hyperechoic septtions nd locules cn e seen ridging the gllldder lumen with honeycom pttern [56]. MRC is not routinely performed for evlution of this type of nomly lthough it is le to demonstrte morphologic normlities nd the internl sept. 7.3 Benign Biliry Neoplsms 7.3.1 Biliry Cystdenom Biliry cystdenom is rre cystic neoplsm tht represents less thn 5% of ll intrheptic cysts of iliry origin tht rise from intr- nd extrheptic ile ducts [27]. This neoplsm my occur nywhere long the intr- or extrheptic ile ducts, lthough out 80% of lesions re found prtly or completely within the liver. The cuse of iliry cystdenom is unknown, lthough it could e relted to congenitl nomly of the iliry primitive ud. This neoplsm cn e clssified s either ) cystdenom with ovrin-like strom, or ) cystdenom without ovrin-like strom. The vrint without ovrin-like strom is oserved primrily in mles nd is considered more ggressive nd more inclined to mlignnt degenertion. The form tht develops predominntly in femles hs n ovrin-like strom nd follows n indolent course. Most lesions re more thn 10 cm in dimeter t dignosis, with internl sept, nd without solid components. Microscopiclly, iliry cystdenom hs mucin-secreting columnr epithelium lining the cysts. The lining cells hve ple eosinophilic cytoplsm nd slly-oriented nuclei, typicl of iliry-type epithelium. The epithelium is supported y mesenchyml strom which is compct nd cellulr [16]. Biliry cystdenom is regrded s pre-mlignnt tumor. Mlignnt trnsformtion into cystdenocrcinom my occur in up to 15% of cses. In situ crcinom with ppillry growth into the cysts my e the only lesion present lthough invsive denocrcinom my lso e seen [35, 68]. Approximtely 90% of these neoplsms occur in middle-ged women. When present, the symptoms re those of growing dominl mss. Right upper qudrnt dominl pin, occsionlly irrditing to the scpul, is the min symptom [8]. On US, iliry cystdenom is seen s lrge hypoechoic, multiloculted cystic-like lesion with intrlesionl sept (Fig. 19). Occsionlly murl nodules occur in enign cystdenom, lthough these re more common within cystdenocrcinom, in which they sometimes form mss. Generlly the liquid content is nechoic nd homogeneous lthough complictions such s hemorrhge or inflmmtion cn increse the liquid echogenecity [33]. Fig. 19,. Biliry cystdenom. US scns (, ) revel hypo- to nechoic lesions with thin sept (rrows)
250 MRI of the Liver c Fig. 20-c. Biliry cystdenom on CT. A hypodense lesion with thin sept is seen on the pre-contrst CT scn (). The sept show enhncement fter dministrtion of iodinted contrst medium (, c) Fig. 21,. Biliry cystdenom on MR. T2-weighted HASTE imges cquired in the xil plne () nd True-FISP imges cquired in the coronl plne () revel lrge, loulted cystic lesions in the right liver loe. The lesions re homogeneously hyperintense due to the fluid component nd thin sept re visile (rrowhed) On CT, these tumors re lrge, low-ttenuting intrheptic msses with loulted mrgins nd generlly thin irregulr wlls with firous sept. Although the cystic prts of the lesions do not enhnce following the intrvenous dministrtion of contrst mteril, the internl septtions, murl nodules nd ppillry projections do show enhncement (Fig. 20) [1, 33]. On MR imging, iliry cystdenom ppers s multiloculted septted mss, whose signl intensity on T1- nd T2-weighted imges depends on the presence of solid ovrin-like strom nd the composition of the cystic fluid, which my e serous, mucinous, ilious, hemorrhgic, or comintion of these fluids (Fig. 21, 22). Low signl intensity within the wll on T2-weighted imges my represent hemorrhge. Following the dministrtion of intrvenous contrst gents, the internl septtions, murl nodules nd ppillry projections enhnce [8]. On heptoiliry phse imges fter dministrtion of hepto-specific contrst gents, no contrst mteril is seen within the cystic cvities, nd no significnt ccumultion is detected in the solid components. Thus the solid components re seen s hypointense res compred with the surrounding liver prenchym.
7 Imging of the Biliry Tree nd Gllldder Diseses 251 c d e f g Fig. 22-g. Biliry cystdenom on MR. On the unenhnced T2-weighted HASTE imge (), hyperintense, cystic lesion with internl sept is visile. On the corresponding T1- weighted ft-suppressed () nd T1-weighted (c) imges, the lesion shows homogeneous low signl intensity. On dynmic contrst-enhnced imging (d, e) (Gd-BOPTA, 0.05 mmol/kg BW) the lesion does not show ny vsculriztion nd the surrounding liver prenchym shows norml perfusion. On the T1-weighted ft-suppressed imge in the equilirium phse (f), the sept nd the cpsule of the lesion (rrows) show contrst enhncement. However, Gd-BOPTA is not visile within the lesion on the T1-weighted imge cquired during the heptoiliry phse (g)
252 MRI of the Liver 7.3.2 Bile Duct Adenom This is rre enign epithelil liver tumor which is minly found incidentlly t lprotomy or utopsy. Its mximl size often does not exceed 1-2 cm. Bile duct denom represents out 1% of ll primry liver tumors. They occur oth in children nd elderly people, nd my e present s solitry nodules or s multiple nodules throughout the liver [62]. Bile duct denoms re typiclly locted on the surfce of the liver. Microscopiclly, smll ile ducts lined y mucin-producing cells re emedded in firous strom. Bsed on immunhistochemicl studies, the most likely pthogenesis is rection to focl ile ductulr injury. Histologiclly, ile duct denoms comprise mss of disorgnized mture periiliry glnd cini nd ductules within vrile mount of connective tissue strom showing signs of chronic inflmmtion nd collgeniztion. The composition of ile duct denom hs resulted in it eing termed periiliry glnd hmrtom [6]. Although the tumor is enign in nture, there hs een the suspicion of mlignnt trnsformtion. Pthologicl differentil dignoses to e considered include ile duct hmrtom, cholngiocellulr crcinom, metstsis nd heptic grnulom. On US, ile duct denom ppers s hyperechoic re with n coustic shdow sometimes surrounded y hyperechoic rim. Similr smll hyperechoic liver lesions re hemngiom, focl nodulr hyperplsi (FNH), heptocellulr crcinom (HCC) nd metstsis. On unenhnced CT, ile duct denom is usully hypodense. However, the presence of clcifictions my give the lesion hyperdense ppernce. On delyed contrst-enhnced CT, the lesions usully demonstrte heterogeneous enhncement, lthough homogeneous enhncement hs lso een descried. The presence of firous strom within the tumor results in the lesion demonstrting prolonged enhncement on contrst-enhnced CT. The tumor is typiclly hypointense on unenhnced T1-weighted imges nd hyperintense on T2-weighted scns. Enhncement of ile duct denoms on dynmic phse imging fter the injection of gdolinium contrst gent my e heterogeneous, ring-shped or homogeneous. As in contrst-enhnced CT, the presence of firous strom within the tumor leds to prolonged enhncement on post-contrst T1-weighted MR imging. Due to its smll size nd peripherl locliztion, ile duct denom is often difficult to detect. It should e included mong the diseses to e differentited from hyperechoic heptic tumors on US nd from heptic tumors showing delyed enhncement on contrst-enhnced CT nd MRI. Bile duct denoms cn frequently e distinguished from other liver tumors y their smller size, their locliztion eneth the liver cpsule, nd their prolonged enhncement [62]. 7.3.3 Biliry Hmrtom Biliry hmrtom is enign neoplsm composed of prolifertion of smll, round, normlppering ducts with cuoidl, slightly sophilic cells tht hve regulr nuclei ut lck ny evidence of dysplsi or incresed mitotic ctivity. In this lesion there is lwys firous supporting strom. This neoplsm occurs minly in ptients of older ge, shows no sex predilection, nd is often ssocited with dult polycystic kidney disese. The lesion my e up to 4 cm in dimeter ut most re 1 cm or less t dignosis. An ssocition etween cholngiocellulr crcinom nd multiple iliry hmrtom hs een reported [43], nd it hs previously een considered rective process rther thn true neoplsm or mlformtion. Biliry hmrtom is sometimes confused with ile duct denom ut it is usully multiple nd distriuted throughout the liver, forming prt of the spectrum of firopolycystic diseses of the liver due to ductl plte mlformtion. Biliry hmrtoms re symptomtic nd re therefore usully incidentl findings t fine needle iopsy, lprotomy or utopsy. Imging findings re usully not specific since these lesions often mimic metstses or scesses. Therefore iopsy is usully required for definitive dignosis. On US, the typicl form of the lesion is chrcterized y multiple, smll, hypoechoic lesions tht ffect ll segments of the liver giving honeycom pttern. On pre-contrst CT imges, numerous, round, smll, hypodense lesions throughout the liver cn e seen. These lesions usully do not show enhncement fter contrst medium dministrtion. On pre-contrst T1- nd T2-weighted MR imges, lesions pper hypointense nd hyperintense, respectively, nd re generlly well-defined (Fig. 23). The nodules do not show enhncement fter dministrtion of heptospecific contrst gents, ecuse the lesions re independent nd do not communicte with the iliry system [50]. 7.3.4 Biliry Ppillomtosis Biliry ppillomtosis is n extremely rre condition chrcterized y the presence of multiple e-
7 Imging of the Biliry Tree nd Gllldder Diseses 253 7.4 Mlignnt Biliry Neoplsms 7.4.1 Cholngiocellulr Crcinom Fig. 23. Biliry hmrtom. The MRC imge revels multiple, well-defined hyperintense round lesions (rrowheds) in oth loes of the liver nign ppillry denoms in the ile ducts, tht re similr to denoms oserved in the intestinl trct. Ppilloms cn e present in the intr- nd extrheptic ile ducts, including the common ile duct. The lesion cn occsionlly e found in the gllldder nd in the mjor pncretic duct. The ppillry excrescences re composed of mucus-secreting columnr epithelil cells supported y thin firovsculr stlks. In some cses it is possile to oserve vrile degrees of structurl nd cytologicl typi. Cliniclly, ptients hve episodes of ostructive jundice, sepsis, nd hemoili [61]. A vrile degree of iliry duct dilttion cn e oserved on imging studies; in some cses intrductl tissue msses re present which my e vrile in size. Cholngiocellulr crcinom (CCC) is primry mlignnt tumor rising from the ile duct epithelium nd comprises 10-25% of ll liver nd iliry trct cncers. CCC is usully clssified s intr- or extrheptic sed on the loction of the involved ducts. Intrheptic CCC cn e further sudivided into peripherl nd hilr. A tumor tht rises peripherl to the secondry ifurction of the left or right heptic duct is considered peripherl intrheptic CCC, wheres tumor tht rises from one of the heptic ducts or from the ifurction of the common heptic duct is considered to e hilr CCC or Kltskin tumor, ccording to Kltskin s description in 1965 (Fig. 24) [31]. Peripherl or loulr intrheptic CCC rises from the epithelium of the internl wll of the smll peripherl intrheptic ile ducts nd represents out 10% of ll tumors. It tends to grow exophyticlly into the liver prenchym s lrge focl mss nd my e polypoid or foclly stenotic. Intrheptic hilr CCC ccount for pproximtely 25% of ll CCC nd re usully scirrhous. Extrheptic CCC ccount for pproximtely 65% of ll CCC [31]. The liver cncer study group of Jpn hs recently proposed new clssifiction for intrheptic CCC s mss-forming, periductl-infiltrting, or intrductl-growing sed on their growth chrcteristics (Fig. 25) [42]. In the mss-forming type, the lesion my e solitry or multiple nd possess stellite nodules round the min mss. The periductl infiltrting type of CCC grows Fig. 24. Bismuth clssifiction of hilr cholngiocellulr crcinom (Kltskin tumors)
254 MRI of the Liver Fig. 25. Intrheptic cholngiocellulr crcinom: new clssifiction of the liver cncer study group of Jpn long the ile duct wll, resulting in concentric thickening of the wll long the ile duct leding to n elongted, spiculted, or rnch-like ppernce. The ile ducts re nrrowed or nerly completely ostructed, nd the involved segments vry in length. The intrductl-growing vrint is chrcterized y the presence of intrluminl ppillry tumors of the intr- or extrheptic ile ducts ssocited with prtil ostruction nd dilttion of the ile ducts. The tumor fills sometimes nd occludes the ile ducts. Primry sclerosing cholngitis, choledochl cyst, fmilil polyposis, congenitl heptic firosis, infection with the Chinese liver fluke Clonorchis sinensis, nd history of exposure to Thorotrst re risk fctors for CCC [14, 38]. A muttion in the p53 tumor suppressor gene hs een demonstrted in peripherl-type CCC, in contrst to the k-rs muttions oserved in lesions tht ffect the extrheptic ile ducts [39, 63]. Ptients dignosed with CCC tend to e older thn those with HCC; CCC occurs most frequently in ptients in their sixth decde, lthough ptients with risk fctors my develop the neoplsm t much younger ge. CCC occurs slightly more frequently in men thn in women. The histologic vrints of CCC include: denocrcinom, mixed CCC-HCC, squmous-, mucoepidermoid-, cystdeno- nd grnulr cell crcinom. Adenocrcinom comprises 95% of the cses, nd cn rnge from well-differentited mucinproducing, to poorly-differentited [44]. Distinguishing morphologicl fetures llow further su-clssifiction of ile duct denocrcinoms into ppillry, sclerosing, nd nodulr vrints. The sclerosing type is most common, followed y ppillry nd nodulr cholngiocrcinom [73]. The gross ppernce of CCC is gryishwhite, firm/solid, firous mss. The cut section usully presents s sclerotic gry-white or ple white, with dense firous strnding. Typiclly, CCC hs lrge centrl core of firotic tissue tht is reltively devoid of neoplstic cells. Cncer cells re minly locted t the periphery of the tumor. Dughter nodules cn e found throughout the liver, oth close to nd distnt from the min mss. Generlly CCC is not highly vsculrized, nd hemorrhge nd necrosis re uncommon. CCC rising from the common ile duct ppers s rounded, reltively smll intrluminl mss. It is usully locted within the mid-extrheptic iliry tree either t the distl common heptic duct or t the common ile duct. The neoplstic cells hve undnt connective tissue strom nd produce vrile desmoplstic rection. The surrounding liver prenchym is generlly non-cirrhotic. Histologiclly, it is often difficult to distinguish CCC from metstses of denocrcinom. In more thn 60-70% of cses, hilr or heptoduodenl ligment lymph nodes re involved. The clinicl signs nd symptoms re relted to the site of origin of the tumor. In intrheptic CCC, the symptoms re usully vgue until the tumor is t n dvnced stge when ptients frequently present with norexi, weight loss, dominl pin, nd plple mss in the upper domen. Fever my occur ut is uncommon. Jundice is rrely presenting symptom in intrheptic CCC, lthough it is common in hilr or ductl CCC [31]. There re no specific tumor mrkers for CCC, lthough elevtions of serum crcinoemryonic ntigen (CEA) nd CA 19-9 re often found
7 Imging of the Biliry Tree nd Gllldder Diseses 255 Fig. 26,. Hilr cholngiocellulr crcinom. US () revels n ill-defined heterogeneous mss (sterisk) with dilted ile ducts (white rrows). An ill-defined infiltrtive mss (sterisk) from the hilus through the heptic prenchym is lso seen (). Some ile ducts round the mss pper dilted (white rrowheds) Fig. 27,. Peripherl cholngiocellulr crcinom. On US, the neoplsm (sterisk) ppers s well-defined heterogeneous nodule () or s n ill-defined mss () compred to the surrounding prenchym [71]. Elevtion of lkline phosphtse nd γ-glutmyltrnsferse my e seen nd ptients my e hypoluminemic nd mildly nemic. On US scns, CCC my hve mixed echogenicity or my e predominntly hypoechoic or hyperechoic. The sonogrphic fetures of Kltskin s tumor include duct dilttion, isoltion of the right nd left ile duct segments, mss or ile duct wll thickening t the hilus s well s lor trophy with crowded, dilted ile ducts. US is ccurte for reveling the level of ile duct ostruction, ut it shows tumor mss in only 20-70% of ptients. When mss is seen, it is usully poorly defined nd echogenic, reflection of the sumucosl, scirrhous nture of this firotic neoplsm (Fig. 26) [10, 20]. Peripherl CCC my pper s n ill-defined mss with mixed echogenecity (Fig. 27) with or without segmentl ile duct dilttion. A hypoechoic hlo is oserved in 33% of cses. Sometimes the centrl portion of the tumor ppers hypoechoic due to the presence of necrosis. Hyperechoic spots with coustic shdowing indicte the presence of clcifictions. The infiltrtive pttern of growth of CCC ppers s diffuse rchitecturl chnges in the heptic loe. Stellite nodules my e seen. Color Doppler US shows scnty color signl ecuse of CCC hypovsculrity. This is useful sign for the differentil dignosis of HCC, which is typiclly hypervsculr neoplsm. Foclly stenotic or ppillry CCC often cuse segmentl ile duct dilttion nd my induce lor trophy if the loction of the tumor is centrl. CCC is usully hypodense or isodense reltive to the norml liver prenchym on unenhnced CT scns. After dministrtion of contrst mteril, most CCC remin hypodense during the portl-venous phse ut therefter show enhncement on delyed phse imges. This pttern of enhncement reflects the hypovsculr, desmoplstic composition of most CCC; therefore, most lesions re etter pprecited 15-20 minutes fter contrst medium dministrtion. Smll necrotic regions re common in lrger lesions. Segmentl or diffuse ile duct dilttion is common finding in hilr CCC (Fig. 28) [10].
256 MRI of the Liver Peripherl type CCC my simulte other heptic neoplsms, such s metstses or hypovsculr HCC. Its most common pttern consists of hypodense ill-defined lesion on unenhnced CT scns, poor, rim-like enhncement during the rteril nd portl-venous phses, nd iso- or hyperdensity on delyed phse imges (Fig. 29). Other fctors such s the grde of the tumor, distriution of firosis, nd contrst pooling cn ffect the delyed enhncement. Peripherl wsh-out is nother sign tht cn e seen on contrst-enhnced CT of peripherl CCC. CCC is either isointense or hypointense reltive to the norml liver on T1-weighted MR imges, ut my rnge from mrkedly to mildly hyperintense on T2-weighted imges. The signl intensity of the tumor is vrile, nd depends on the mount of mucinous mteril, firous tissue, hemorrhge nd necrosis within the tumor [70]. On dynmic T1- weighted MR imges cquired fter the intrvenous dministrtion of gdolinium, miniml or moderte incomplete enhncement is seen t the tumor periphery on erly imges, wheres progressive centrl contrst-enhncement is seen on lter imges (Fig. 30) [70]. The degree of enhncement vries with the type of tumor. Greter peripherl enhncement is noted in the erly phses in lrge CCC, wheres greter enhncement is noted in the firous core of scirrhous CCC on delyed phse imges (Fig. 31). Smll, incidentlly discovered intrheptic CCC, s well s mixed CCC/HCC tumors cn show intense, homogeneous enhncement during the rteril phse with prolonged enhncement on delyed phses due to mrked hypervsculrity [70, 74]. Generlly, lesions show peripherl hypointensity nd centrl iso- or hyperintensity on delyed phse imges fter the dministrtion of contrst gents with liver-specific properties (Fig. 30, 31). However, the centrl re my lso show incomplete enhncement. Stellite nodules re seen in out 10-20% of CCC cses nd re chiefly responsile for the poor prognosis of this lesion (Fig. 32). Pooling of contrst within the tumor, nd peripherl wsh-out on delyed MR imges re suggestive findings of CCC in non-cirrhotic ptients. This chrcteristic enhncement pttern reflects the lrge mounts of firous tissue, neovsculrity, nd neoplstic cells t the periphery of the lesion. A significnt signl drop of the lesion is not detected fter SPIO dministrtion, nd therefore the neoplsm ppers significntly more hyperintense thn norml liver prenchym. The use of MRC in conjunction with MRI permits the extent of the tumor in ile ducts to e determined. With this technique hilr ostruction nd some segment dilttions cn e esily dignosed. A common finding on ll imging techniques is the presence of lymphodenopthy. Lymph nodes re typiclly lrge nd round nd hypoechoic, hypodense, nd hypo- or hyperintense on US, CT, nd MR studies, respectively, nd show uptke of isotope on positron emission tomogrphy (PET) exmintions (Fig. 33). 7.4.2 Biliry Cystdenocrcinom Biliry cystdenocrcinom is rre cystic neoplsm tht cn rise within liver cysts, ile ducts, nd in the context of polycystic liver disese. It lso rises s result of the mlignnt trnsformtion of iliry cystdenom. Since mlignnt degenertion of iliry cystdenom my require s few s ten yers, resection of cystdenom is recommended. As in iliry cystdenom, there exists two forms of iliry cystdenocrcinom, those with nd those without ovrin-like strom. Microscopiclly, the neoplsm my contin either mucinous or serous mteril lthough mucus is more common. These lesions re sometimes symptomtic nd re therefore discovered incidentlly. More frequently ptients present with pin, jundice, nuse, nd fever [51]. Unlike cystdenom, iliry cystdenocrcinom ppers s multiloculted complex cystic mss with irregulr wll thickness, internl septtions, nd ppillry projections on US nd CT. MR imging revels irregulr wlls, internl septtions, murl nodules nd ppillry projections within the lesion. The solid portions show enhncement fter intrvenous dministrtion of gdolinium contrst gent [8].
7 Imging of the Biliry Tree nd Gllldder Diseses 257 c Fig. 28-c. Hilr cholngiocellulr crcinom. On unenhnced CT () nd erly post-contrst dynmic phse CT (), the neoplsm (white rrows) ppers s n illdefined hypodense mss locted ner the hilum. Bile duct dilttions (rrowhed) re lso evident. On delyed phse imges fter contrst medium dministrtion the lesion is seen s hyperttenuting (c) c Fig. 29-c. Peripherl cholngiocellulr crcinom. On unenhnced CT () the lesion (sterisk) ppers s well-defined hypodense mss. Miniml enhncement is seen on imges cquired during the portl-venous phse fter dministrtion of contrst mteril () while in the equilirium phse (c) the neoplsm is seen s heterogeneously hyperdense compred to the liver, which is due to undnt firotic desmoplstic rection
258 MRI of the Liver c d e f g h Fig. 30-h. Hilr cholngiocellulr crcinom. On the unenhnced T2-weighted TSE imge () the neoplsm (white rrows) ppers slightly heterogeneously hyperintense compred to the norml liver nd involvement of the ile duct system cn e seen. On the unenhnced T1-weighted GRE imge () the lesion ppers s slightly hypointense ill-defined mss. Poor enhncement is seen during the rteril phse fter the olus dministrtion of Gd-BOPTA (c). However, desmoplstic rection cuses progressive increse of contrst enhncement in susequent cquisitions during the portl-venous nd equilirium phses (d nd e, respectively). After 20 minutes the lesion (rrowhed) ppers hyperintense (f). Due to the lrge mount of firotic tissue which cuses non-specific contrst gent retention, the lesion retins this hyperintense ppernce on imges cquired one hour fter Gd-BOPTA dministrtion (g). Nevertheless, the presence of hypointense peripherl rim indictes the mlignnt nture of the lesion. The involvement of hilr ile ducts (rrow) is clerly demonstrted with MRCP (h)
7 Imging of the Biliry Tree nd Gllldder Diseses 259 c d e f Fig. 31-f. Peripherl cholngiocellulr crcinom. The neoplsm (white rrow) ppers heterogeneously hyperintense on unenhnced T2-weighted imges () nd hypointense on unenhnced T1-weighted imges (). Moderte peripherl enhncement is seen on imges cquired during the rteril (c) nd portl-venous (d) phses fter the dministrtion of Gd-BOPTA. On the equilirium nd delyed phse imges (e nd f, respectively) the enhncement ppers progressive nd complete due to desmoplstic rection. A hypointense rim (white rrowheds) indicting peripherl wsh-out cn e seen on the delyed-phse imge
260 MRI of the Liver Fig. 32,. Cholngiocellulr crcinom. On the unenhnced T2-weighted imge () lrge heterogeneously hyperintense mss (sterisk) nd numerous stellite nodules (rrowheds) cn e seen. On the imge cquired during the heptoiliry phse fter injection of Gd-BOPTA (), the iggest nodule shows centrl enhncement nd peripherl wsh-out while the smller stellite nodules (rrowheds) remin hypointense Fig. 33,. Cholngiocellulr crcinom. The post-contrst CT scn () shows homogeneous, slightly hypodense, lymphodenopthy (rrow) djcent to the portl vein. The lesion is confirmed on the PET exmintion () s nodule tht shows isotope uptke (rrow)
7 Imging of the Biliry Tree nd Gllldder Diseses 261 7.5 Benign Neoplsms of the Gllldder 7.5.1 Gllldder Adenom Gllldder denom is rre enign neoplsm of glndulr epithelium tht is usully polypoid, single, nd well-demrcted. The neoplsm is more common in middle-ged women nd cn lso occur in children, lthough more rrely. Adenoms re clssified s tuulr, ppillry, or tuuloppillry ccording to their pttern of growth. Microscopiclly they re clssified s pyloric, glnd type, intestinl type, nd iliry type [2]. Gllldder denoms re usully smll nd symptomtic, nd re usully discovered incidentlly during cholecystectomy. Occsionlly, however, they cn e lrge or multiple, with typicl symptoms including upper right dominl pin, jundice, nd vomiting. Sometimes denoms of the gllldder occur in ssocition with Peutz-Jegher syndrome or Grdner s syndrome [2]. On US denoms pper s homogeneously hyperechoic smll, rod-sed, non-shdowing, pedunculte or sessile polypoid defects (Fig. 34). These lesions do not move with grvittionl mneuvers, nd the echogenicity is inferior to tht oserved with stones. In generl, CT nd MR imging re not used for the dignosis of gllldder denom. Fig. 34. Gllldder denom. US revels smll, well-defined, hyperechoic, sessile lesion (rrow) 7.6 Mlignnt Neoplsms of the Gllldder 7.6.1 Gllldder Crcinom Gllldder crcinom is the fifth most common mlignncy of the gstrointestinl trct [37]. While there doesn t pper to e ny difference etween mles nd femles in the incidence of gllldder crcinom, there re indictions of demogrphic differences in the ge of ptients dignosed with this neoplsm: in the United Sttes the verge ge t dignosis is out 70 yers, while in Indi it is 40-50 yers. The four most importnt fctors ssocited with the development of gllldder crcinom re genetic nomly, gllstones, congenitl norml choledocho-pncretic junction, nd porcelin gllldder. With regrds to genetic fctors, muttion of the k-rs gene, overexpression of the c-erb-2 gene nd decresed expression of the nm23 gene hve een oserved in ptients with gllldder crcinom [13, 18]. An ssocition etween gllldder crcinom nd gllstones is well known, nd this cusl reltionship is the reson for performing cholecystectomy for cholelithisis s preventive mesure for gllldder crcinom. Gllldder crcinom is ssocited with n norml choledocho-pncretic junction ecuse in this condition pncretic juice cn reflux into the common ile duct. The mixture of pncretic juice nd ile leds to chronic inflmmtion of the gllldder with susequent metplsi, dysplsi, nd crcinom [30]. Finlly, porcelin gllldder, which is diffuse clcifiction of the gllldder wll, is lso predisposing fctor: n estimted 22% of ptients with porcelin gllldder develop crcinom [7, 55]. Approximtely 60% of ll neoplsms originte in the fundus of the gllldder, while 30% originte in the ody nd 10% in the neck. Nerly 85% of primry crcinoms of the gllldder re denocrcinoms; the reminder re nplstic or squmous cell crcinoms. The denocrcinoms cn e sudivided into vrious sutypes, including well-differentited, ppillry, intestinl, pleomorphic gint cell, poorly-differentited smll cell, nd cler cell types. Histologiclly, gllldder crcinoms hve three mjor ptterns of presenttion: 1) focl or diffuse thickening of the gllldder wll; 2) polypoid mss originting in the gllldder wll nd projecting into the lumen; 3) mss oscuring or replcing the gllldder, often invding djcent liver, with or without multiple stellite nodules [59, 60].
262 MRI of the Liver Fig. 35. Gllldder crcinom. US revels n heterogeneous, hypo- nd hyperechoic mss (white rrows) tht replces the gllldder. A corse stone with coustic shdow cn e seen within the mss (rrowhed) Lymph node involvement is lso common finding in gllldder crcinom. Most ptients with crcinom of the gllldder present with either cute cholecystitis or symptoms of mlignncy, including constnt right upper dominl qudrnt pin, mlise, weight loss, nd jundice. Ptients sometimes hve long history of episodic cholecystitis. Gllldder crcinom is occsionlly n incidentl finding on dominl imging studies [40]. On US, gllldder crcinoms my cuse mild to mrked murl thickening in focl or diffuse pttern with irregulr nd mixed echogenicity. Crcinoms confined to the gllldder mucos my present s flt or slightly rised lesions with mucosl irregulrities tht re difficult to pprecite sonogrphiclly. On the other hnd, polypoid crcinoms my e hyperechoic, hypoechoic, or isoechoic reltive to the liver. These lesions re fixed to the gllldder wll, nd do not cuse n coustic shdow. Gllstones re usully present, in which cse lrge mss oscuring or replcing the gllldder is common presenttion (Fig. 35). The echotexture of this mnifesttion is often complex with regions of necrosis nd smll mounts of pericholecystic fluid often present [60, 69]. Color Doppler US usully shows hypovsculr mss. However, color signl my e seen t the periphery due to the hypervsculrity of the peripherl components [69]. CT is inferior to US for evluting the gllldder wll for mucosl thickening or irregulrity. Focl mlignnt wll thickening nd polypoid cncer re oth usully hyperdense on CT imges cquired fter the dministrtion of intrvenous contrst mteril. However, infiltrting crcinom tht replces the gllldder often shows irregulr contrst enhncement with scttered regions of internl necrosis (Fig. 36) [60]. Invsion of the liver, stellite lesions, nd ile duct dilttion re common findings in this form of gllldder crcinom [69]. The MR findings for gllldder crcinom re similr to those reported for CT. The tumor usul- c d Fig. 36-d. Gllldder crcinom on CT. Unenhnced CT () revels n ill-defined slightly hypodense mss (white rrows) surrounding corse irregulr, nd heterogeneous stone (white rrowhed). In the rteril phse fter contrst mteril dministrtion () the neoplsm remins poorly-delineted nd poorly-enhnced. In the portl-venous phse (c) the lesion ppers heterogeneously isodense, ut etter defined ginst the norml liver. In the equilirium phse (d) the neoplsm is more homogeneous nd thin hyperdense peripherl rim cn e seen
7 Imging of the Biliry Tree nd Gllldder Diseses 263 c d e f g Fig. 37-g. Gllldder crcinom on MR. On T2-weighted imges () gllldder stone (rrow) together with some solid mteril in the gllldder cn e seen infiltrting the surrounding liver tissue of the right liver loe. On the corresponding T1-weighted imge the infiltrting tissue ppers hypointense (). On T1-weighted ft-suppressed imges (c) some hyperintense res indictive of hemorrhge cn e noted inside the solid components. Arteril phse T1-weighted imges cquired fter the olus dministrtion of Gd-BOPTA revel irregulr enhncement of the periphery of the infiltrted right liver loe (d). Enhncement (rrow) of ppillry solid res in the gllldder cn lso e detected on portl-venous phse imges (e). This is even more ovious on T1-weighted ft-suppressed imges in the equilirium phse (f) in which tumor growth in the gllldder is clerly visulized (rrow). Additionlly, homogeneous enhncement of the infiltrtion of the right liver loe due to desmoplstic rection cn e noted, which is typicl for cholngiocellulr crcinom. In the heptoiliry phse (g), the infiltrted res of the right liver loe re once gin hypointense, evidencing the mlignnt nture of the lesion. Note the excretion of the contrst gent in the ile duct (rrow) nd the enhncement of the surrounding liver tissue compred with the unenhnced T1-weighted imge. ly hs incresed signl intensity reltive to the liver on T2-weighted imges nd poorly-delineted contours. These lesions re either isointense or hypointense reltive to the liver on T1-weighted imges. The tumor generlly shows poor nd heterogeneous enhncement on dynmic phse imging nd often ppers hyperintense on ft-suppressed T1-weighted imges in the equilirium phse [57]. On delyed heptoiliry phse imges fter the dministrtion of Gd-BOPTA, the tumor ppers s heterogeneous hypointense mss (Fig. 37). A significnt signl drop is usully not seen fter SPIO dministrtion nd the lesion is usully hyperintense compred to the norml liver prenchym [57]. 7.6.2 Gllldder Crcinoid Gllldder crcinoid is rre tumor tht represents less thn 1% of ll digestive trct crcinoids. Ptients re usully young or middle-ged dults nd there is no cler sex predominnce. Associ-