Patterns of intrahepatic bile duct dilatation at CT: correlation with obstructive disease processes

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  • Sharlene A. Teefey, MD #{149}Richard L. Baron, MD #{149}Scott J. Schulte, MDRandall M. Patten, MD #{149}Margaret H. Molloy, MD

    Patterns of Intrahepatic Bile Duct Dilatationat CT: Correlation with ObstructiveDisease Processes

    I From the Department of Radiology, University of Washington School of Medicine, Seattle(SAT., R.L.B., 5.1.5., R.M.P., M.H.M.); and the Department of Radiology, University of PittsburghSchool of Medicine, Pittsburgh (R.L.B.). Received May 20, 1991; revision requested June 21; revisionreceived July 26; accepted August 5. Address reprint requests to SAT., Seattle Veterans AffairsMedical Center, 1660 5 Columbian Way, Seattle, WA 98108.

    , RSNA, 1992Abbreviation: PSC = primary sclerosingchobangitis.

    The authors performed a blinded,retrospective analysis of 100 com-puted tomographic (CT) scans of pa-tients with proved extrahepatic bileduct obstruction, including primarysclerosing chobangitis (PSC), to deter-mine whether certain patterns of in-trahepatic bile duct dilatation aresuggestive of specific disease pro-cesses. Among 30 patients with be-nign obstructive disease, CT showedpruning of the intrahepatic ducts infour patients (13%), beading in four(13%), and skip dilatations in one(3%). Among 54 patients with malig-nant obstructive disease, CT illus-trated pruning in eight (15%) pa-tients, beading in 11 (20%), and skip

    dilatations in two (4%). Among 16patients with PSC, CT demonstratedpruning in four (25%), beading in two

    (13%), and skip dilatations in five(31%). The majority of patients withmalignant or benign obstructive dis-ease or PSC had intrahepatic ductdilatation in both lobes of the liver. Itextended into the periphery in 46 of54 patients (85%) with malignant ob-structive disease, in 20 of 30 (67%)with benign obstructive disease, andin 10 of 16 (63%) with PSC. The CTfinding of skip dibatations is stronglysuggestive of PSC. The CT findingsof pruning and beading are nonspe-cific and may be observed at CT inpatients with bile duct obstructiondue to a wide variety of causes. Thedistribution and extent of intrahe-patic duct dilatation at CT do not dif-fer among bibiary disease processes.

    Index terms: Bile ducts, CT, 765.1211 #{149}Bile

    ducts, enlarged, 765.36 #{149}Bile ducts, stenosis or

    obstruction, 765.288 #{149}Cholangitis, 765.288

    Radiology 1992; 182:139-142

    P AST reports have described certaincomputed tomographic (CT)

    findings as suggestive of primary scle-

    nosing cholangitis (PSC) (1,2). CT find-

    ings observed in the intrahepatic bile

    ducts in these patients included scat-

    tered, focal areas of peripheral ductdilatation with no visible connectionto the central hilar ducts (termed skipdilatations) and segments of irregular

    duct dilatation producing a beadedappearance (1,2). We have also de-scnibed CT findings of intrahepatic

    duct pruning, beading, and skip diba-tations associated with PSC but havestated that the specificity of these CTfindings is unknown (3). We under-

    took a blinded, retrospective review

    of CT scans from 100 patients withproved bile duct obstruction of vary-ing causes (including PSC) to deter-mine whether certain patterns of in-

    trahepatic bile duct dilatation aresuggestive of specific disease pro-

    cesses.

    MATERIALS AND METHODS

    Medical, surgical, and radiobogic recordswere reviewed to identify CT studiesshowing abnormally dilated intrahepatic

    ducts (visualization of only the central

    night and left hepatic ducts was consid-

    ered normal). One hundred CT studies

    were selected to include a variety of dis-

    ease processes with proved.extrahepaticbiliary obstruction. CT studies were per-

    formed on one of three types of scanners:GE 9800 (GE Medical Systems, Milwaukee)(n = 34), GE 8800 (GE Medical Systems)(n = 50), or Picker 1200 (Picker Interna-tionab, Highland Heights, Ohio) (ii = 16).Contrast material was administered intra-venously with a bolus rapid-infusion tech-nique. As this was a retrospective study,scan techniques varied with the clinical

    indications. The collimation used was pre-dominantly 5 or 10 mm (in one case it was3 mm), and scan intervals were either 5 or

    10 mm.CT scans of the intrahepatic biliary sys-

    tem were evaluated for the following find-ings: (a) pruning, considered presentwhen on a single CT section a dilated in-trahepatic bile duct (excluding the central

    right and left ducts) was observed over a4-cm or greater segment without the ex-pected, dilated side branches (Fig 1);(b) beading, considered present when atbeast three closely alternating regions ofdilatation and stenosis were observed inan intrahepatic duct on a single CT section(Fig 2); and (c) skip dilatation, consideredpresent when CT images showed isolated,dilated peripheral ducts with no visibleconnection to dilated central ducts or withno connection to other dilated ducts oncontiguous CT sections (Fig 3).

    The distribution and extent of the intra-

    hepatic duct dilatation were also evalu-ated. Dilatation was either limited to thecentral two-thirds of the liver (other than

    the central right and left hepatic ducts) orextended into the peripheral one-third. AllCT findings were retrospectively evalu-ated by three of the investigators (R.L.B.,S.J.S., R.M.P.), who were blinded to the

    diagnosis and who viewed masked imagesshowing only the liver and not the porta

    hepatis and distal common bile duct. Aconsensus of opinion was achieved in all

    but one case, in which two of three read-ens considered beading not present and

    one considered it present. For purposes ofanalysis, beading was scored as not

    present in this case.Medical records were reviewed to deter-

    mine the clinical diagnosis at the time ofthe CT examination. Thirteen pathologicconditions causing extrahepatic bile ductobstruction anywhere from the level ofthe porta hepatis to the ampulla were

    identified: pancreatic carcinoma (n = 25),PSC (ii = 16), common bile duct stones(n = 15), chobangiocarcinoma (n = 14),metastatic disease (n = 9), pancreatitis(n = 7), chobedochocyst (n = 3), lym-phoma (n = 3), gallbladder carcinoma(n = 2), papillary stenosis (n = 2), recur-

  • a. b.Figure 1. Pruning. (a) CT scan of a patient with PSC shows a left intrahepatic duct stricture(arrowheads) with dilatation proximally and distally. The expected dilated side branches are

    absent, which correlates with the cholangiographic finding of pruning. Also noted are spleno-megaly and enlargement of the lateral segment of the left lobe of the liver secondary to cirnho-sis. (Reprinted, with permission, from reference 3.) (b) CT scan of a patient with pancreatic

    carcinoma shows no pruning; expected dilated side branches are present (arrowheads).

    .k

    rent pyogenic cholangitis (n = 2), hepato-cellular carcinoma (iz = 1), and ascendingcholangitis (n = 1). The clinical diagnosiswas confirmed by means of tissue speci-men examination (percutaneous on exci-sionab biopsy) in 60 patients and cholan-

    giography in 30. In these 90 patients in

    whom histologic proof on cholangio-graphic evidence of the diagnosis was ob-

    tamed, the time interval between the diag-nosis and the CT study was 1 week or bessin 46 patients, 1-2 weeks in 14, and greaterthan 2 weeks in 30. The clinical diagnosiswas confirmed by the clinical presentationand follow-up findings in four additionalpatients and by examination of a tissuespecimen from a primary neoplasm withclinical and imaging findings compatible

    with metastatic disease in six. In these 10patients, clinical and/or imaging conreba-tion was made at the time of the CT study.The diagnosis of PSC was based on find-ings at chobangiography and a clinical

    course excluding malignancy in all 16cases.

    For purposes of analysis, cases were cat-egonized as follows: (a) benign obstructivedisease (excluding PSC diagnosed bymeans of cholangiography), includingcommon bile duct stones, pancreatitis,chobedochocyst, papillary stenosis, recur-rent pyogenic cholangitis, and ascendingcholangitis; (b) malignant obstructive dis-ease, including pancreatic carcinoma,cholangiocarcinoma, metastatic disease,bymphoma, gallbladder carcinoma, andhepatocellubar carcinoma; and (c) PSC.

    RESULTS

    Benign Obstructive Disease

    Common bile duct stones-Amongthe 15 patients, CT showed pruningof the intrahepatic ducts in one andbeading in one. Skip dibatations werenot identified. Intrahepatic duct dila-tation was present in both lobes in 14patients and in one lobe in one. It wascentral in four patients and extendedinto the periphery in 10. In the casewith duct dilatation limited to onelobe, dilatation was central.

    Pancreatitis.-Among the seven pa-tients, CT demonstrated pruning of

    the intnahepatic ducts in one. Beadingand skip dibatations were not ob-served. Intrahepatic duct dilatationwas present in both lobes in all seven

    patients. It was central in four pa-

    tients and extended into the peniph-

    ery in three.Others (choledochocyst, papillary steno-

    sis, recurrent pyogenic cholangitis, and

    ascending cholangitis).-Among theeight patients, CT illustrated beading

    of the intrahepatic ducts in three pa-

    tients (recurrent pyogenic cholangitis,chobedochocyst, ascending cholangi-

    tis), pruning in two (recurrent pyo-

    genic cholangitis, papillary stenosis),

    and skip dilatations in one (recurrent

    pyogenic cholangitis). Intrahepatic

    duct dilatation was present in both

    lobes in all eight patients. It was cen-

    trab in one patient and extended into

    the periphery in seven.

    Summary.-In the 30 patients with

    benign obstructive disease, CTshowed pruning of the intrahepatic

    ducts in four, beading in four, and

    skip dibatations in one. Intrahepatic

    duct dilatation was present in both

    lobes in 29 patients and in one lobe in

    one. It was central in nine patientsand extended into the periphery in

    20. In the case with duct dilatation

    limited to one lobe, dilatation was

    central.

    Malignant Obstructive Disease

    Pancreatic carcinoma-Among the25 patients, CT demonstrated pruning

    in four patients and beading in seven.

    Skip dibatations were not observed.

    Intrahepatic duct dilatation waspresent in both lobes in 24 patients

    and in one lobe in one. It was central

    in two patients and extended into the

    periphery in 22. In the one case withduct dilatation limited to one lobe,

    dilatation was central.

    Cholangiocarcinoma.-Among the 14patients, CT showed pruning in three

    patients and beading in three. Skip

    dilatations were not observed. Intra-

    hepatic duct dilatation was present in

    both lobes in all 14 patients. It was

    central in one patient and extendedinto the periphery in 13.

    Others (metastatic disease, lymphoma,

    gallbladder carcinoma, and hepatocellularcarcinoma).-Among the 15 patients,

    CT illustrated pruning in one patient

    Figure 2. Beading in a patient with PSC. CTscan shows closely alternating regions of di-

    latation and stenosis (arrowheads) in an in-

    trahepatic duct. (Reprinted, with permission,

    from reference 3.)

    (metastatic disease), beading in one

    (bymphoma), and skip dibatations in

    two (metastatic disease). In these bat-

    ten two cases of skip dilatations, he-

    patic metastases were present and

    visualized on CT scans between the

    segments of interrupted ducts. Intra-

    hepatic duct dilatation was present in

    both lobes in 12 patients and in one

    lobe in three. It was central in two

    patients and extended into the pe-

    riphery in 10. In the three patients

    with duct dilatation limited to one

    lobe, dilatation was central in two and

    peripheral in one.

    Summary-In the 54 patients withmalignant obstructive disease, CT

    showed pruning of the intrahepatic

  • a. b.

    Figure 3. Skip dilatations in a patient with PSC. (a) CT scan shows isolated, dilated peniph-eral ducts (arrowheads) with no visible connection to dilated central ducts. (b) Contiguous CTsection also does not show a connection to dilated central ducts.

    Volume 12 #{149}Number 1 Ra1iolnav #{149}141

    ducts in eight patients, beading in 11,

    and skip dibatations in two. Intrahe-patic duct dilatation was present in

    both lobes in 50 patients and in one

    lobe in four patients. It was central in

    five and extended into the periphery

    in 45. In the four cases with duct dila-

    tation limited to one lobe, dilatation

    was central in three and peripheral in

    one.

    PSC

    Among the 16 patients, CT demon-

    strated pruning in four patients,

    beading in two, and skip dilatations

    in five. Intnahepatic duct dilatation

    was present in both lobes in 15 pa-

    tients and in one lobe in one. It was

    central in six patients and extended

    into the periphery in nine. In the one

    case with duct dilatation limited to

    one lobe, dilatation was peripheral.

    Summary of CT Findings

    Beading was seen at CT in 17 pa-

    tients, pruning in 16, and skip dibata-

    tions in eight. Of the 17 patients with

    beading, seven had pancreatic carci-

    noma, three had chobangiocancinoma,

    two had PSC, and one each had lym-

    phoma, recurrent pyogenic cholangi-

    tis, common bile duct stones, chole-

    dochocyst, on ascending cholangitis.

    Of the 16 patients with pruning, four

    had pancreatic carcinoma, four had

    PSC, three had cholangiocarcinoma,

    and one each had metastatic disease,

    recurrent pyogenic cholangitis, papib-

    bary stenosis, pancreatitis, or common

    bile duct stones. Of the eight patients

    with skip dibatations, five had PSC,

    two had liver metastases (separating

    the proximal and distal duct dilata-

    tion) clearly demonstrable at CT, and

    the remaining patient had recurrent

    pyogenic cholangitis.

    Intrahepatic duct dilatation was

    present in both lobes in 94 patients

    and in one lobe in six. Of the 94 pa-

    tients with intnahepatic duct dibata-

    tion in both lobes, 50 had malignant

    obstructive disease, 29 had benign

    obstructive disease, and 15 had PSC.

    Of the six patients with intrahepatic

    duct dilatation limited to one lobe,

    four had malignant obstructive dis-

    ease, one had benign obstructive dis-

    ease, and one had PSC.

    There were six patients with intra-

    hepatic duct dilatation limited to one

    lobe. Four patients had malignant ob-

    structive disease, one had benign ob-

    structive disease, and one had PSC.

    Intrahepatic duct dilatation was

    central in 24 patients and extended

    into the periphery in 76. Of the 24

    patients with central dilatation, 10

    had benign obstructive disease, six

    had PSC, and eight had malignant

    obstructive disease. Of the 76 patientswith extension of duct dilatation into

    the periphery, 46 had malignant ob-

    stmuctive disease, 20 had benign ob-

    structive disease, and 10 had PSC.

    DISCUSSION

    CT has become an accepted method

    for evaluating intra- and extrahepatic

    biliary obstruction. Several studieshave reported that CT is accurate in

    determining the presence and distni-

    bution of bile duct dilatation as well

    as the bevel and cause of the obstruct-

    ing lesion (4-10). Recently, authorshave reported an association betweenPSC and the CT findings of beading,

    pruning, and skip dibatations in the

    intrahepatic ducts (1-3). However,

    these studies analyzed only patientswith known PSC, and to date no

    blinded or controlled study has been

    performed-to our knowledge-to

    determine whether these CT findings

    are specific for PSC.

    Our blinded, retrospective review

    shows that pruning is not spec...

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