Download Understanding Biliary Dyskinesia: The Role of the Sphincter of Oddi and Cholecystokinin and more Exams Nuclear medicine in PDF only on Docsity!
years until Boyden's detailed work put an end to uncertainty (8). The functional role of the sphincter of Oddi is now widely accepted. The sphincter consists of three parts: one surrounding the intraduodenal part ofthe distal CBD, called the choledochal sphincter; one at the distal end of the pancreatic duct (duct of Wirsung), called pancreatic sphincter; and one surrounding the common channel, called the ampullary sphincter. The distal end of the common duct, surrounded by the ampullary sphincter, opens into second part of the duodenum at the postero-medial wall at an elevation called the ampulla of Vater. The name sphincter of Oddi generally refers to all three sphincters (Fig. 1).
Bile Flow Of600 ml ofbile produced by the liver per day (0.4 ml/min), about 70% enters the gallbladder during fasting, and the remaining 30% enters the duodenum directly (9). The volume of hepatic bile that partitions between the two organs is dependent on the sphincter of Oddi tone, which is maintained by periodic contractions. During fasting, the sphincter of Oddi exhibits a median of 4 contractions/mm, of which approxi mately 80% proceed antegrade, 13% proceed retrograde and the remaining 9% occur simultaneously at three levels within the sphincter (Table 1). The basal mean pressure of 15 mmHg between contractions rises to 135 mmHg at the peak of the phasic wave (10). Cholecystokinin administration normally abolishes the phasic wave activity and promotes dilation of the sphincter of Oddi, facilitating smooth passage of the bile it receives from the gallbladder.
Cholecystokinin In 1928, Ivy and Oldberg (2) first proposed a hormonal mechanism for contraction and emptying of the gallbladder induced by acidification ofupper small intestine, and named the hormone CCK. For a while, it was also called pancreozymin because it increased the production ofpancreatic enzymes (11). Later, it was shown that a single hormone produced both effects (12). Because the gallbladder effect was described first, the title
ofCCK has been restored.Meal ingestion stimulatesthe release
ofCCK fromcells scatteredin the mucosa ofthe duodenumand
upperjejunum (Fig. 1). There are no CCK-secreting cells in the esophagus, stomach or intestine, beyond the terminal jejunum (13). Two forms of CCK have been identified: one with 33 and another with 39 amino acids. The form with 33 amino acids is the most abundant. The biological action ofthe hormone resides mainly at the C-terminal tetrapeptide (14). Cholecystokinin- can be cleaved at different locations (Fig. 2), and the fragment that retains the C-terminal tetrapeptide continues to have most of the biological function of the parent molecule (15). Other peptides such as gastrin and cerulein, which have the identical C-terminal tetrapeptide, also possess a cholecystokinetic effect.
A peptide consisting ofthe terminaleight amino acids (CCK-8)
ofthe hormone has been synthesized and marketed as Sincalide or Kinevac. The seventh amino acid, tyrosine, is sulfated, which
The availability of objective and quantitative diagnostic tests in recent years has allowed more precise documentalion of biliary dyskinesia. Biliary dyskinesia consists of two disease entities situ
atedattwo differentanatomicallocations:sphincterof Oddispasm,
at the distal end of the common duct, and cystic duct syndrome, in the gallbladder.Bothconditionsarecharacterizedby a paradoxical responsein which the sphincterof Oddi and the cystic duct contract (andimpedebileflow)insteadof undergoingthe normaldilatation, when the physiological dose of cholecystokinin is infused. Quanti tative cholescintigraphycan clearly differentiateone disease entity from the other. The therapiesof choice are sphincterotomy,sphinc teroplasty or antispasmodics for sphincter of Oddi spasm and cholecystectomy for cystic duct syndrome. After quantitative
cholescintigraphy,the final impressionshouldidentifythe disease
entity by name to assist the referring physiCian in making an appropriate therapeutic decision; a mere statement that a test is consistent with biliary dyskinesia is no longer sufficient.
Key Words biliary dyskinesia; cholecystokinin; sphincter of Oddi spasm; gallbladder cystic duct syndrome
J Nuci Med 1997;3&1824-.
Clinicalacceptanceoftheroleofquantitativebiliarydynamic
studies has progressed slowly, and only recently have quanti tative biliary dynamic studies gotten the attention of practicing clinicians. Historically, this has been typical for the acceptance of any new knowledge in biliary anatomy, physiology or pathology. First, doubts were expressed about the existence of a sphincter at the distal end of the common bile duct (CBD). Later, questions were raised as to the cause of contraction and emptying of the gallbladder. When the existence of the sphinc ter of Oddi (1) and the hormone mechanism [cholecystokinin
(CCK)] for gallbladderemptying (2) were proposed and con
firmed, new doubts were expressed about the entity of biliary dyskinesia (3). Measurement of sphincter of Oddi dynamics by biliary manometry (4) and gallbladder and bile duct emptying by cholescintigraphy (5) have allowed for objective documen tation of biliary dyskinesia. The entity of biliary dyskinesia is now well-defined (6), and appropriate therapeutic options are available (7). Diagnosis of biliary dyskinesia requires a clear understanding of the physiological relationship between the sphincter of Oddi and the gallbladder and of the effect of CCK on them in both good health and disease. In this article, we first will review the basic pathophysiology and later summarize the scintigraphic approach to the diagnosis of biliary dyskinesia.
SPHINCTER OF ODDI
In 1887, Rugero Oddi first proposed a sphincter mechanism at the distal end of the CBD, which today bears his name (1). The presence of the sphincter remained controversial for many
ReceivedNov.12,1996;revisionacceptedJan.20,1997. Forcorrespondenceor reprintscontactS. Kiishnamurthy,MD.NudearMedicine, TUaIity community Hospital, 335 8th Ave. S.E, Hilisboro, OR 97123.
1824 THEJou@u'@i.OFNUCLEARMEDICINE•Vol. 38 •No. 11 November 1997
Biliary Dyskinesia: Role of the Sphincter of Oddi,
Gallbladder and Cholecystokinin
Shakuntala Krishnamurthy and Gerbail T. Krisbnamurthy
Nuclear Medicine Department, Tuality Community Hospital, Hillsboro, Oregon; and Nuclear Medicine Section/Imaging Service, Veterans Affairs Medical Center, and University ofArizona, Tucson, Arizona
NormalParameters Median Range Abnormal
CCK-Receptor Duct
CCKSecreting Cell
FIGURE 1. Sphincter of Oddi. Choledochal sphincter covers the intraduoderiai part of the CBD before it joins the pancrea@c duct. The pancreatic sphincter coversthedistalendof thepancreaticduct.Theampullarysphinctercoversthecommonthannelformedbytheunionof theCBDandthepancreaticduct (ductof Wirsung).Thenamesphincterof Oddirefersto allthreesphincters.
is an essential requirement for retaining the biologic potency of the hormone (16).
Actions of Cholecystokinin In addition to inducing gallbladder contraction, pancreatic enzyme secretion and sphincter of Oddi dilatation, CCK has many other biological actions:
Contraction and emptying of the gallbladder. Relaxation of the sphincter of Oddi. Increase in pancreatic enzyme secretion. Increase in secretion of insulin, glucagon and somtatostatin by Islet cells. Inhibition of gastric emptying by contraction of the pyloric sphincter. Increase in hepatic bile secretion. Increase in intestinal peristalsis. Increase in intestinal blood flow. Suppression of appetite. Decrease in systolic blood pressure.
Cholecystokinin acts by attaching to CCK receptors (Fig. 1) distributed in the smooth muscle of the gallbladder and sphinc ter of Oddi (1 7). The degree of gallbladder emptying is CCK dose-dependent. Gallbladder ejection fraction increases as the dose is enhanced from 0.5 ng/kg/min to 3.3 ng/kg/min ( ng/kg/3 mm) and then begins to decrease when larger doses are infused, especially when CCK is given as a rapid intravenous bolus (18). This seemingly paradoxical response in normal subjects is attributed to the different threshold level ofthe CCK receptors in the body, fundus and cystic duct. In animals, it was shown that the cystic duct smooth muscle threshold for CCK induced contraction is much higher than the threshold for
contraction of the muscle in the body and fundus of the gallbladder (19). The cystic duct, therefore, does not contract when a physiological dose of CCK is infused. When large, nonphysiological CCK doses are given, however, the gallblad der ejection fraction decreases, probably related to cystic duct contraction when the dose exceeds the threshold value for contraction (18). The degree of gallbladder emptying also is related directly to the total number of receptors in the gallblad der wall smooth muscle (20). In addition to inducing contrac tion of the gallbladder, CCK simultaneously relaxes the sphinc ter of Oddi, mainly by abolishing phasic wave activity (Fig. 3). The sphincter of Oddi relaxation is attributed to the binding of CCK to inhibitory receptors. The dose recommended in the Sincalide package insert was developed for oral cholecystogram and for inducing pancreatic enzyme production and was found
TABLE I
Pressure and Wave Frequency, Sequence and Amplitude Changes in a Normal Sphincter of Oddi
Basalpressure(mmHg) Waveamplitude(mmHg) Wavefrequency(noimin) Sequence Antegrade(%) Simultaneous(%) Retrograde(%)
ReproducedfromRef 10withpermissionfromtheauthorandpublisher.
15 5- 135 95— 4 2-
80 12— 13 0- 9 —
BILIARY DYSKINESIA •Krishnamurthy and Krishnamurthy 1825
Sphincter
36K @X@K- GB @28K pain
,@20I( 36Yr -RUOpain
minutes
Cystic Duct Syndrome
@@ @0K -
@@@ .E
.@ •@ •
@ (^) 0 @0K GBEF•4.5% 0
.@ 67Y@-RUQpsin @@50K . 0 0.... , 5 10 15 20 25 30 mk@jtss
nwn Hg Co@ad@1-t--@-@―V―LY@/-
MmdI. @
@ Ca@ad @ @ccK- Time in Seconds
FIGURE4. Effectof CCK-8on the sphincter ina patientwithSOS. Notethe exaggerationof contractionwaveswith CCK-8andthe predominantretro gradepropagation,whichresultsin contractionof the sphincterinsteadof normaldilatation.(Reprintedwfth permissionof the authorfrom:ToouliJ, Roberts-ThompsonIC,DentJ, LeeJ. Mahonietricdisordersin patientswfth suspectedsphincterof Oddidysfunction.Gastmenterology1985;88:1243- 1250.)
Major pathophysiology of the syndrome resides in the cystic duct itself. There is kinking, fibrosis and thickening of the wall and narrowing ofthe lumen ofthe cystic duct (31). Hepatic bile enters the gallbladder, often slowly, but cannot get out readily on feeding or injection of CCK. In the literature, it is also known by such names as chronic acalculous gallbladder disease or chronic acalculous cholecystitis. Cholesdnbgraphic Diagnosis A proper patient preparation, data acquisition and analysis is critical for diagnosis. The patient is asked to fast for a minimum of 4 hr and preferably for 8 —10hr. All drugs known to act on the sphincter of Oddi (e.g., opioids, calcium channel blockers, nitrates etc.) and gallbladder are discontinued for an appropriate length oftime, depending on plasma T112ofthe drug. It is much easier to analyze the data when the hepatic and gallbladder phase studies are obtained separately on the computer (32). Hepatic Phase Imaging Anterior view images are acquired at 1 frame/mm for 60 mm with 2—4mCi of 99mTc..mebrofenin using a large field-of-view gamma camera fitted with a low-energy, all-purpose, parallel hole collimator. The planar images are reformatted and photo graphed at two frames per image. A time-activity curve is generated over the upper right hepatic lobe. Liver peak uptake time and excretion T112 are obtained from the liver curve. Hepatic extraction fraction, which allows for the separation of hepatic from biliary disease, is calculated when deconvolution software is available (33,34). Characteristics of bile formation and flow are analyzed from the planar images, with particular reference to the time of appearance of the gallbladder, intestine and CBD. The common bile duct is scrutinized for its size, course, bile pooling and any evidence of tapering or an abrupt cutoff sign (9). Gallbladder Phase Imaging These data are acquired as a separate 30-mm study between 60 and 90 mm after 99mTc@mebrofenininjection. If there was any superimposition of the duodenal and CBD radioactivity during the hepatic phase imaging, an attempt is made to separate them during the gallbladder phase by angling the camera in whatever direction and degree separates them max imally. In some patients, it may be an RAO view; in others, it may be an LAO view; and in most others, it could be the same angle that was used during the hepatic phase imaging. Duodenal activity, if present, can be cleared by asking the patient to drink a glass of water. The data are collected at 1 frame/min for 30 mm. Five milliliters of saline are infused slowly at 2 mm as a placebo, and CCK-8 is infused through an infusion pump beginning at 5 mm, at a dose of 10 ng/kg/3 mm. Before saline and CCK-8 infusion are begun, the patient is instructed to raise
FIGURE5. Gallbladderemptying in a patient with SOS (top) and CDS (bottom). Note normal ejection fraction and rapid refilling soon after the cessationof CCK-8infusionin SOSand a low ejectionfractionwith no refilling in CDS.
her hand as soon as pain is felt and to raise it again when the pain is relieved. These time intervals are recorded and shown on the gallbladder curve (Fig. 5). The ejection fraction is calculated in the standard fashion (5,9). High-contrast biliary images are obtained and scrutinized carefully for evidence of bile reflux into common hepatic, right hepatic and left hepatic ducts during the ejection period. Rapid refilling ofthe gallbladder is checked both on the gallbladder curve and the planar images. In patients with postcholecystectomy CBD dilatation, a region of interest is drawn over the common duct (common hepatic duct + CBDs) from its origin at the junction of the right and left hepatic ducts to its termination at the duodenum, taking care not to include any of the intestinal activity. Post-CCK-8 ejection fraction and ejection rate for the common duct are calculated similar to the gallbladder (33). Hepatic phase parameters aid in differentiating CBD stenosis from SOS. The gallbladder phase parameters help to differen tiate SOS from CDS and provide quantification ofthe degree of abnormality. In patients with cholecystectomy who have CBD dilatation, CCK stimulation helps to document presence or absence of obstruction by measuring ejection fraction and ejection rate for CBD (34). Cholescintigraphic Features of Sphincter of Oddi Spasm Scintigraphic features may depend upon the presence or absence of the gallbladder. In patients with an intact gallblad der, scintigraphy usually shows normal anatomy of the CBD during the hepatic phase imaging, with minimal or no evidence
BILIARY DYSKINESIA •Krishnamurthy and Krishnamurthy 1827
Sphincter of Oddi Spasm
of bile pooling in the intra- or extrahepatic bile ducts. These features are quite different from those seen in stricture of the
CBD, where there is intense bile pooling proximal to obstruc
tion (9). The time to peak hepatic uptake may be delayed (26,35) or within normal range (36). The liver shows an increase in percent residual activity at 45 and 60 mm, with decrease in the rate of liver bile emptying (27). Hepatic hilum to duodenal transit is increased (36). Extrahepatic ducts appear early and persist for a longer duration, especially in those patients with cholecystectomy. After CCK-8 infusion, the gallbladder may show a normal or slightly low ejection fraction. Almost all of the bile emptied from the gallbladder may reflux into common hepatic, right hepatic and left hepatic ducts during the ejection period and re-enter the gallbladder immediately upon cessation of CCK-8 infusion. The CBD curve shows a peak corresponding to this reflux in patients with an intact gallbladder (35). This sign also is noted in association with stricture of the CBD (37). The intrahepatic ducts can accom modate almost all of the bile emptied from the gallbladder ( ml), without being dilated. Many, but not all, patients expen ence pain during the ejection period, and the pain is usually relieved when the gallbladder relaxes and begins to refill (Fig. 5). In patients without a gallbladder, cholescintigraphy shows prominent bile stasis within intra- and extrahepatic ducts and marked delay in time to hepatic peak (35,38). Cholecystokinin injection increases hepatic bile production and washes out bile stasis within the ducts rapidly when there no anatomic obstruc tion (33). This response is very similar to that of a lasix test in kidneys to rule out obstruction at the uretero-pelvic junction. The bile-emptying rate from CBD with stricture is much lower than in normal subjects. In subjects with an intact gallbladder, the normal bile-emptying rate is 3.5%/mm or higher (9). The distinction between anatomic stricture (stenosis) versus fImc tional obstruction also is made by administering amyl nitrite during cholescintigraphy (39). In five reports totaling 67 pa tients with suspected SOS, cholescintigraphy identified all patients, for a sensitivity of 100%, when any one of the abnormal parameters was used as evidence of SOS (26,27,36,38,39). Such results are not universal, and caution should be exercised during data acquisition, analysis and interpretation (35). The average scintigraphic sensitivity for SOS in the literature is between 70% and 90% (40). It is likely that many of the functional parameters described above may need further modification because a large number of patients is studied under different imaging protocols.
Scintigraphic Features of Cystic Duct Syndrome
On scintigraphy,most of the gallbladderswith CDS are seen
within 60 mm, but some may be delayed for 3—4hr due to slow absorption of water through the wall (32). The bile ducts are seen as normal during the hepatic phase imaging. On CCK- injection, the gallbladder shows a low ejection fraction. The exact duration of gallbladder ejection may be difficult to measure in some because the curves are often flat (Fig. 5). There is usually no bile reflux into common hepatic, right and left hepatic ducts. In five reported series, of a total of 281 patients with CDS who had cholecystectomy solely on the basis of low ejection fraction, 247 (88%) had relief of pain, and 250 patients (89%) had histological evidence of cystic duct or gallbladder abnormality (41—45). Based on such excellent outcome, more and more surgeons now feel confident perform ing cholecystectomy solely on the basis of a low ejection fraction.
ROLE OF NUCLEAR MEDICINE
The pain of biliary dyskinesia, in the beginning, is neither severe nor constant, and for these reasons, many patients tolerate it for a long time before seeking medical aid. When patients finally do seek medical help, their problem is not clarified immediately because of normal routine liver function tests and normal ultrasound studies of the gallbladder and the
CBD. Only upon repeatedpresentationdo the clinicians begin
to consider biliary dyskinesia as a possibility and request these functional hepatobiliary studies. Patients are referred to nuclear medicine by the primary care physician under many different names, including to rule out “papillarystenosis, biliary spasm, postcholecystectomy syndrome, biliary pain, CDS or chronic acalculous gallbladder disease― or under some other vague diagnosis (3). Only a few physicians request the studies under the title “biliarydyskinesia.― Because of unfamiliarity with quantitative biliary dynamic studies, the entity of biliary dys kinesia is probably underdiagnosed at this stage. A well informed nuclear medicine physician can address a clinician's concern after knowing the clinical problem and custom-design the test for the patient. Attention is given to proper technical details including patient preparation, duration of fasting and infusion ofphysiological doses of CCK-8. All drugs that act on the sphincter and gallbladder (opiates, nitrates, calcium channel blockers, etc.) are discontinued before the test. Recording of the exact time of onset and relief of pain and its relation to the shape of the gallbladder curve is important in delineating the temporal relationship ofpain to the gallbladder-emptying phase (Fig. 5). Pain occurring outside the gallbladder-emptying phase is probably nonbiliary in origin. Because the action of CCK includes an increase of intestinal peristalsis (see “Actionsof Cholecystokinin―), late-onset pain may suggest an intestinal origin of pain.
FUTURE The liver is the largest organ in the body and carries out the most complex biologic function. It concentrates about 98% of the injected dose of @Tc-mebrofenin and rapidly secretes into bile (excretion T112= 16 mm). Almost 70% ofthe radioactivity secreted by the liver enters the gallbladder during fasting, giving excellent counts for imaging and quantitation. The normal physiological relation and complex pathological con nection that exists among the sphincter ofOddi, gallbladder and
CCK in patientsoffers a greatopportunityfor nuclearmedicine
to unravel the mystery. The appropriate therapy for CDS is cholesystectomy and, for SOS, it is sphincterotomy, sphinctero plasty or antispasmodics. Cholecystectomy for SOS may be inappropriate. Therefore, it is important to differentiate these two conditions to allow the referring physician to make an appropriate therapeutic decision (Fig. 6). An inappropriate response (contraction) by the cystic duct and the sphincter of Oddi to normal doses of CCK-8 is attributed to activation of inhibitory receptors, which normally remain unresponsive. In
CDS and SOS, these inhibitory CCK receptors become acti
vated and respond by contraction (Fig. 6, middle and right), preventing bile emptying through the cystic duct and the sphincter of Oddi, respectively (19). In CDS, the gallbladder counts in response to CCK-8 may decrease minimally or remain the same, whereas in SOS, the gallbladder counts may decrease significantly by emptying bile into the CBD (with reflux into common hepatic duct and right and left hepatic ducts and other segmental intrahepatic ducts), but the counts increase immedi ately due to refilling (Fig. 5) after cessation of CCK-8 infusion.
A clear understandingof normal physiological changes and
variations in pathology among the sphincter of Oddi, the cystic
1828 THEJOURNALOFNUCLEARMEDICINE•Vol. 38 •No. 11 November 1997
41. Pickelman J, Peiss RL, Henkin R, Salo B, Nagel P. The role of sincalide cholescin tigraphy in the evaluation of patients with acalculous gallbladder disease. Arch Surg l985;l20:693—697.
- Fink-Bennet D, DeRidder P, Kolozsi WZ, Gordon R, Jaros R. Cholecystokinin cholescintigraphy: detection of abnormal gallbladder motor function in patients with chronic acalculous gallbladder disease. J Nucl Med l991;32:1695—1699.
- Zech ER, Simmons LB. Kendrick RR, et al. Cholecystokinin enhanced hepatobiliary
scanning with ejection fraction calculation as an indicator ofdisease ofthe gallbladder. Surg Gynecol Obstet l991;172:2l—24.
- MisraDC,BlossomGB,Fink-BennetD, et al. Resultsof surgicaltherapyforbiliary dyskinesia.Arch Surg 199l;l26:957—960. 45. Halverson JD, Gamer BA, Siegel BA, et al. The use of hepatobiliary scintigraphy in patients with acalculous biliary disease. Arch Intern Med l992;l52:l305—l309.
1830 THEJOURNALOFNUCLEARMEDICINE•Vol. 38 •No. 11 ‘November 1997
