Scintigraphic evaluation of bile dynamics before and after endoscopic sphincterotomy

Influence of cholecystectomy on the flow dynamic pattern of bile in the extrahepatic bile duct: Assessment by cine-dynamic MRCP with spatially-selective IR pulse

PURPOSE

To evaluate the influence of cholecystectomy on the flow dynamic pattern of bile in the extrahepatic bile duct by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively.

MATERIALS AND METHODS

56 patients with cholecystectomy and 48 control subjects without cholecystectomy who underwent cine-dynamic MRCP with spatially-selective IR pulse at 1.5 T or 3 T (TR/TE, 4000 msec/500 msec; echo train spacing, 6.5 msec; echo train length, 172; section thickness, 50 mm; matrix, 320 × 320; field of view, 320 × 320 mm; bandwidth, 488 Hz; and inversion time, 2200 msec). In cine-dynamic MRCP, IR pulse with 20 mm width was placed on the common bile duct (CBD) to evaluate the movement of bile (antegrade and reversed bile flow). Cine-dynamic MRCP imaging was scanned every 15 s (imaging, 4 s; rest, 11 s) during 5 min to acquire a series of single-shot images (a total of 20 images). The frequency that antegrade or reversed bile flow was observed in the extrahepatic bile duct, and 5-point grading score based on the moving distance of antegrade or reversed bile flow were compared between the groups. Both groups were compared using the χ² and Mann-Whitney U tests (P < 0.05 considered significant).

RESULTS

Antegrade bile flow was observed more frequently in the cholecystectomy group than in the non-cholecystectomy group (5.1 times vs. 2.8 times, P = 0.008). Mean grading score of antegrade bile flow was significantly greater in the cholecystectomy group than in the non-cholecystectomy group (mean grade, 0.33 vs 0.21; P = 0.014). Regarding reversed bile flow, there were no significant differences in the frequency and grading score between cholecystectomy group and non-cholecystectomy group.

CONCLUSION

Antegrade bile flow was observed more frequently and predominantly in patients after cholecystectomy in cine-dynamic MRCP with spatially-selective IR pulse while reversed bile flow was observed equivalently.

Negative Impact of Indwelling Biliary Stent on Gallbladder Visualization on Cholescintigraphy

PURPOSE

Presence of biliary stent may alter biliary dynamics, which may change the results of cholescintigraphy. We assessed the frequency of gallbladder (GB) nonvisualization and its specificity for acute cholecystitis (AC) in patients with stent.

PATIENTS AND METHODS

Of 44 with stent who had cholescintigraphy, 22 were excluded because of prior cholecystectomy or little to no radiotracer excretion from the liver precluding assessment of GB filling. Cholescintigraphy performed on the remaining 22 with stent and their medical records were reviewed. We also assessed the frequency of GB nonvisualization in the comparison group of 1044 without stent who had cholescintigraphy for evaluation of AC.

RESULTS

Gallbladder was not visualized in 21 (96%) of 22 with stent, 10 of whom did not have high clinical suspicion of AC. Gallbladder was visualized in only 1 patient on delayed imaging at 4 hours. Four had cholecystectomy, 3 had chronic cholecystitis and 1 AC superimposed on chronic cholecystitis. The highest possible specificity derived from our data assuming an extreme hypothetical scenario was only 25% with the true specificity likely being 7% or lower. In contrast to patients with stents, only 188 (18%) of the 1044 without stent had GB nonvisualization (P < 0.0001).

CONCLUSIONS

In patients with stents, cholescintigraphy using morphine augmentation or 4-hour delayed imaging is futile to evaluate for AC because the frequency of GB nonvisualization is high and the specificity of GB visualization is low. It is unknown whether further delayed imaging at 24 hours would improve the study efficacy in this population.

Assessment of physiologic bile flow in the extrahepatic bile duct with cine-dynamic MR cholangiopancreatography and a spatially selective inversion-recovery pulse

PURPOSE

To determine the feasibility of directly and noninvasively visualizing physiologic bile flow in the extrahepatic bile duct by means of nonpharmacologic cine-dynamic magnetic resonance (MR) cholangiopancreatography with a spatially selective inversion-recovery (IR) pulse and assess the flow dynamic pattern of bile in the extrahepatic bile duct.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need for informed consent. Thirty-five patients without known pancreatobiliary diseases and 11 patients with dilatation of the extrahepatic bile duct were included. Cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse was performed by imaging every 15 seconds over a 5-minute interval (20 images acquired total). The images were evaluated for the visualization of bile flow, the frequency that bile flow was observed in the extrahepatic bile duct, and the distance the bile moved within the area of the IR pulse. Statistical analysis was performed by using Spearman rank correlation coefficient and Mann-Whitney U tests.

RESULTS

Antegrade bile flow was observed in 29 of 35 patients (83%) in the nondilated group. Bile flow was observed much more frequently in the nondilated group than in the dilated group (4.4 times vs 1.8 times, P = .029). The distance that bile moved forward within the area of the IR pulse was significantly greater in the nondilated group than in the dilated group (mean grade, 0.44 vs 0.14; P = .033), suggesting stagnation or slowdown of antegrade bile flow in patients with biliary dilatation. Reversed bile flow was also observed in 26 of 35 patients (74%) in the nondilated group without biliary diseases.

CONCLUSION

Nonpharmacologic cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse allows direct and noninvasive visualization of bile flow in the extrahepatic bile duct, demonstrating that reversed bile flow is a physiologic phenomenon.

Nuclear medicine tests for acute gastrointestinal conditions

Acute cholecystitis (AC) and lower-gastrointestinal (GI) bleeding are 2 emergencies commonly encountered in nuclear medicine. Evidence of AC on hepatobiliary scintigraphy (HBS) allows for confident diagnosis and provides support for definitive surgical treatment. Proper patient preparation is essential for HBS including fasting and the use of pharmacologic adjuncts is sometimes required. Pharmacologic adjuncts may also be administered during HBS to shorten the length of the examination and increase its specificity. In the interpretation of HBS, there are several sources of false-positive results to be aware of, most commonly chronic cholecystitis. False-negative results on HBS are usually the result of mistaking another structure, such as a dilated cystic duct, for the gallbladder. Abdominal ultrasound is the appropriate initial test in patients with suspected AC, but HBS is an excellent second tier test for the diagnosis of AC in the work-up of indeterminate cases by sonography. GI bleeding scintigraphy plays an important role in the evaluation and management of patients with acute lower-GI bleeding. Scintigraphy serves to localize sites of active GI bleeding and stratify those patients who would benefit from aggressive treatment (surgery or arteriography) vs those who can be managed medically. Pretest involvement of respective services is critical for successful bleeding site confirmation and therapy by interventional radiology or surgery or both. Single photon emission computed tomography/computed tomography erythrocyte scintigraphy has demonstrated superior accuracy and precision over planar scintigraphy in the diagnosis of acute GI bleeding. Additionally, single photon emission computed tomography/computed tomography scintigraphy of GI bleeding provides useful supplemental anatomical information that benefits patient management.

Hepatobiliary scintigraphy in acute cholecystitis

Hepatobiliary scintigraphy is a mature imaging technique for evaluation of patients with acute cholecystitis (AC). It is effective in calculous and acalculous forms of AC. The test is used in contemporary medical practice as the arbiter when the findings from screening abdominal ultrasound do not fit a clinical picture. It is also performed in severely ill patients who have AC suspected on other testing, but whose frail condition and high operative risk demand the highest level of certainty. This review, therefore, examines all technique variations of hepatobiliary scintigraphy, offering an approach that may best fit a variety of clinical situations and philosophies on AC.

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