Multimodality Imaging of Cholecystectomy Complications

Cholecystectomy is one of the most common surgeries performed in the United States. Although complications are uncommon, the high incidence of this surgery means that a radiologist will likely encounter these complications in practice. Complications may arise in the immediate postoperative period or can be delayed for weeks, months, or years after surgery. Vague and nonspecific symptoms make clinical diagnosis challenging. As a result, multimodality imaging is important in postoperative evaluation. US and multidetector CT are the usual first-line imaging modalities. Hepatobiliary scintigraphy, SPECT/CT, and MRI with conventional or gadoxetate hepatobiliary contrast material are important and complementary modalities that are used for workup. The authors begin with a brief discussion of surgical technique and expected postoperative findings and then describe complications organized into four groups: (a) biliary complications, (b) stone-related complications, (c) iatrogenic complications, and (d) gallbladder complications. Biliary complications include bile leaks and bilomas, acute biliary obstruction, and biliary stricture. Stone-related complications include retained and recurrent stones and spillage of stones into the peritoneum. Iatrogenic complications include hemorrhage, vasculobiliary injury, arterial pseudoaneurysms, duodenal injury, and migration of clips. Gallbladder complications include recurrent cholecystitis after subtotal reconstituting cholecystectomy and unexpected gallbladder cancer. An invited commentary by Mullens and Ibrahim is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Biliary excretion of gadobenate dimeglumine causing degradation of magnetic resonance cholangiopancreatography (MRCP)

PURPOSE

To assess the effect of gadobenate dimeglumine on magnetic resonance cholangiopancreatography (MRCP) and determine an appropriate time frame for performing MRCP sequences.

MATERIALS AND METHODS

2D MRCP sequences obtained after intravenous administration of gadobenate dimeglumine or gadobutrol over 14 months were reviewed retrospectively in randomized order by five abdominal radiologists, using a 3-point scale to rate biliary and pancreatic duct clarity (1 = no-, 2 = limited-, 3 = good visualization). Intraclass correlation coefficients were computed and mean scores were compared for both agents. For gadobenate dimeglumine exams, time delays between arterial phase and MRCP acquisition times were analyzed concerning duct clarity. For gadobutrol, only exams with delays ≥ 15 min were included.

RESULTS

134 exams (107 gadobenate dimeglumine, 27 gadobutrol) were included. Moderate reliability for pancreatic duct visualization and excellent reliability for visualization of intrahepatic bile ducts and upper and lower extrahepatic bile ducts were noted. No difference in mean scores was noted for pancreatic duct visualization (p = 0.66). Bile duct segment scores were lower with gadobenate dimeglumine (mean: 2.1-2.6) compared with gadobutrol (mean: 2.8-2.9) (p ≤ 0.006). For gadobenate dimeglumine, visualization scores varied depending on the delay between the arterial phase and MRCP acquisition (p ≤ 0.047). Good visualization for all bile duct segments was noted with delays of 7.2-9.4 min (95% confidence interval; mean 8.3 min).

CONCLUSION

Bile duct clarity degraded on MRCP images with an increasing delay following gadobenate dimeglumine injection. 2D MRCP, thus, should be performed within 7.2 min after obtaining the arterial phase sequence to ensure good visualization of the entire biliary system.

Recommendations on the use of magnetic resonance imaging in PSC-A position statement from the International PSC Study Group

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disorder characterized by inflammation and fibrosis of the intra- and/or extrahepatic bile ducts. Magnetic resonance imaging (MRI) is a noninvasive imaging modality that can be used to diagnose PSC and detect disease related complications. Quantitative MRI technologies also have the potential to provide valuable prognostic information. Despite the potential of this imaging technology, the clinical application of MRI in the care of PSC patients and imaging standards vary across institutions. Moreover, a unified position statement about the role of MRI in the care of PSC patients, quality imaging standards, and its potential as a research tool is lacking.

CONCLUSION

Members of the International PSC Study Group and radiologists from North America and Europe have compiled the following position statement to provide guidance regarding the application of MRI in the care of PSC patients, minimum imaging standards, and future areas of research. (Hepatology 2017;66:1675-1688).

Balanced MR cholangiopancreatography with motion-sensitised driven-equilibrium (MSDE) preparation: feasibility of Gd-EOB-DTPA-enhanced biliary examination

AIM

To evaluate the effectiveness of motion-sensitised driven-equilibrium (MSDE)-prepared balanced magnetic resonance cholangiopancreatography (MRCP) in a gadolinium ethoxybenzyl diethylene triamine pentaacetic acid (Gd-EOB-DTPA)-enhanced study compared to conventional T2-weighted MRCP.

MATERIALS AND METHODS

Fifteen patients (seven male and eight female patients) prospectively underwent conventional three-dimensional turbo spin-echo T2-weighted MRCP and MSDE-balanced MRCP using a 1.5 T MRI system after hepatobiliary phase image acquisition. For quantitative evaluation, the contrast-to-noise ratio (CNR) of the common hepatic duct to liver tissue was calculated. For qualitative analysis, two radiologists evaluated the depiction of the biliary system and main pancreatic duct (MPD) using a scoring system. Signal suppression of the portal vein (PV) and hepatic vein (HV) on MSDE-balanced MRCP was also scored.

RESULTS

MSDE-balanced MRCP showed significantly higher CNR than T2-weighted MRCP. For all biliary structures, the mean depiction scores of MSDE-balanced MRCP were significantly higher than those of T2-weighted MRCP, whereas the mean depiction score of MPD with MSDE-balanced MRCP was significantly lower than that of T2-weighted MRCP. Signal suppression of the PV and HV was thought to be clinically sufficient.

CONCLUSIONS

MSDE-balanced MRCP more clearly depicted biliary structures compared with T2-weighted MRCP in a Gd-EOB-DTPA-enhanced study. This sequence may be utilised for routine MRCP on Gd-EOB-DTPA-enhanced MRI.

Gadoxetic acid: pearls and pitfalls

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

MR imaging of the biliary system

Although ultrasound, computed tomography, and cholescintigraphy play essential roles in the evaluation of suspected biliary abnormalities, magnetic resonance (MR) imaging and MR cholangiopancreatography can be used to evaluate inconclusive findings and provide a comprehensive noninvasive assessment of the biliary tract and gallbladder. This article reviews standard MR and MR cholangiopancreatography techniques, clinical applications, and pitfalls. Normal biliary anatomy and variants are discussed, particularly as they pertain to preoperative planning. A spectrum of benign and malignant biliary processes is reviewed, emphasizing MR findings that aid in characterization.

MR signal changes on hepatobiliary imaging after oral ingestion of manganese chloride tetrahydrate: preliminary examination

PURPOSE

To clarify magnetic resonance (MR) signal changes during hepatobiliary imaging after oral ingestion of manganese chloride tetrahydrate (Bothdel Oral Solution 10) (MCT).

MATERIALS AND METHODS

Subjects were an MCT phantom, 10 healthy volunteers and 155 consecutive patients. The phantom study evaluated the relationship between MCT concentration and MR signal intensity. The volunteer study qualitatively and quantitatively analyzed the time course of hepatobiliary imaging immediately and 30, 60, 120 and 180 min after oral ingestion of MCT. The clinical study analyzed the incidence and factors affecting signal changes on additional MRCP with MCT as a final scan during routine clinical MRCP.

RESULTS

In the phantom study, a significant and excellent positive linear correlation was found between MCT concentration and R2* measurement (r(2) = 0.996, p < 0.01). In the volunteer study, biliary imaging and hepatic R2* values changed significantly after oral ingestion of MCT (p < 0.05). In the clinical study, a signal drop on MRCP with MCT was visually confirmed in 14.8 % of cases. Multivariate logistic regression found no factors significantly affecting signal drop.

CONCLUSION

We recommend performing MRCP early after oral ingestion of MCT, because signal changes occur even during routine MRCP.

Magnetic resonance imaging of the pediatric pancreaticobiliary system

Magnetic resonance cholangiopancreatography (MRCP) is an extremely useful tool for evaluating a wide variety of disorders affecting the pancreaticobiliary system in neonates/infants, children, and adolescents. This imaging technique has numerous distinct advantages over alternative diagnostic modalities, such as endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography, including its noninvasive nature and lack of ionizing radiation. Such advantages make MRCP the preferred first-line method for advanced imaging the pediatric pancreaticobiliary tree, after ultrasonography. This article presents a contemporary review of the use of MRCP in the pediatric population, including techniques, indications, and the imaging appearances of common and uncommon pediatric disorders.

Flip angle modulations in late phase Gd-EOB-DTPA MRI improve the identification of the biliary system

OBJECTIVES

To assess the improvement of bile duct visualization in Gd-EOB-DTPA enhanced MR-cholangiography (EOB-MRC) by using an increased flip angle.

METHODS

35 patients underwent Gd-EOB-DTPA enhanced MRI of the liver including T2-weighted MRCP and hepatobiliary phase EOB-MRC using a flip angle of 10° (FA10) and of 35° (FA35), respectively. Images were evaluated regarding the delineation of biliary ducts, the order of branching and anatomic visualization of the biliary tree. ROI analysis was performed to estimate the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios.

RESULTS

Applying the FA35 resulted in a significantly better SNR and CNR as compared to FA10. The overall image quality was rated as good for both, FA10 and FA35. The overall rating for regional delineation of the biliary system was rated significantly better for FA35 than for FA10 (p=0.02). Classification of bile duct anatomy variations, however, was equivalent in both techniques.

CONCLUSIONS

Increasing the flip angle of a T1-weighted 3D-sequence from 10° to 35° during the hepatobiliary phase of Gd-EOB enhanced MRI visually and quantitatively improved the visualization of the biliary ducts.

Primovist, Eovist: what to expect?

Gadolinium ethoxybenzyl dimeglumine (Gd-EOB-DTPA, Primovist in Europe and Eovist in the USA) is a liver-specific magnetic resonance imaging contrast agent that has up to 50% hepatobiliary excretion in the normal liver. After intravenous injection, Gd-EOB-DTPA distributes into the vascular and extravascular spaces during the arterial, portal venous and late dynamic phases, and progressively into the hepatocytes and bile ducts during the hepatobiliary phase. The hepatocyte uptake of Gd-EOB-DTPA mainly occurs via the organic anion transporter polypeptides OATP1B1 and B3 located at the sinusoidal membrane and biliary excretion via the multidrug resistance-associated proteins MRP2 at the canalicular membrane. Because of these characteristics, Gd-EOB-DTPA behaves similarly to non-specific gadolinium chelates during the dynamic phases, and adds substantial information during the hepatobiliary phase, improving the detection and characterization of focal liver lesions and diffuse liver disease. This information is particularly relevant for the detection of metastases, and for the detection and characterization of nodular lesions in liver cirrhosis, including early hepatocellular carcinomas. Finally, GD-EOB-DTPA-enhanced magnetic resonance imaging may provide quantitative assessment regarding liver perfusion and hepatocyte function in diffuse liver diseases. The full potential of GD-EOB-DTPA-enhanced magnetic resonance imaging has to be established further. It is already clear that GD-EOB-DTPA-enhanced magnetic resonance imaging provides anatomic and functional information in the setting of focal and diffuse liver disease that is unattainable with magnetic resonance imaging enhanced with non-specific contrast agents.

Hepatobiliary MR imaging with gadolinium-based contrast agents

The advent of gadolinium-based "hepatobiliary" contrast agents offers new opportunities for diagnostic magnetic resonance imaging (MRI) and has triggered great interest for innovative imaging approaches to the liver and bile ducts. In this review article we discuss the imaging properties of the two gadolinium-based hepatobiliary contrast agents currently available in the U.S., gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared toward optimizing workflow and imaging quality are also discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents and will stimulate the reader's pursuit of new applications for future benefit.

MR liver imaging with Gd-EOB-DTPA: a delay time of 10 minutes is sufficient for lesion characterisation

OBJECTIVES

To assess whether, in patients with normal liver function, a hepatobiliary delay time of 10 min after Gd-EOB-DTPA injection is sufficient for lesion characterisation.

METHODS

In 42 consecutive patients with suspected focal liver lesions, dynamic MRI was performed after intravenous Gd-EOB-DTPA, followed by hepatobiliary phases at 5, 10 and 20 min. The following items were assessed at each hepatobiliary phase: parenchymal enhancement, contrast agent excretion in bile ducts, lesion enhancement characteristics (hypo-, iso-, or hyperintensity, rim enhancement, central non-enhancement), and contrast- and signal-to-noise ratios, separately for hypo- and hyperintense lesions.

RESULTS

Following enhancement, parenchymal signal intensity increased significantly up to 10 min (86.3%, P < 0.001), and subsequently stabilised (86.5% after 20 min, P = 0.223). Biliary contrast agent excretion was first observed in 2, 32 and 5 patients after 5, 10 and 20 min respectively. Hepatobiliary lesion enhancement characteristics observed after 5 min persisted during later hepatobiliary phases. CNR and SNR ratios increased significantly (P < 0.05) up to 10 min after enhancement without further increase at 20 min, in hypo- and hyperintense lesions.

CONCLUSIONS

If lesion characterisation is the primary reason for performing MRI, a hepatobiliary delay time of 10 min after Gd-EOB-DTPA injection is sufficient in patients with normal liver function.

KEY POINTS

• Magnetic resonance imaging is now a first line of investigation of the liver. • Optimal CNR and SNR are achieved 10 min after Gd-EOB-DTPA injection. • Typical enhancement characteristics are observed early and do not change. • Ten-minute hepatobiliary delay is sufficient for characterisation of focal liver lesions.

Determination of cystic duct patency using hepatobiliary MRI with gadoxetate disodium: is T1 precontrast imaging necessary?

PURPOSE

To determine the need for precontrast T1-weighted imaging in determining cystic duct patency using hepatobiliary phase imaging with gadoxetate disodium-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

MRI exams using gadoxetate disodium from October 4, 2008 to April 14, 2010 were reviewed in a retrospective fashion. Two reviewers independently reviewed only the 20-minute T1-weighted delayed postcontrast images to determine the presence of excreted contrast in the gallbladder lumen. Contrast was deemed present if hyperintense signal material was seen in the antidependent portion of the gallbladder lumen. The actual presence of contrast in the gallbladder was determined by directly comparing the pre- and postcontrast T1-weighted images using consensus review.

RESULTS

In all, 187 cases were included. Three (1.6%) were deemed indeterminate due to complete homogeneous opacification of the gallbladder. All three cases were identified as indeterminate by both reviewers. Of the remaining 184 cases, 136 filled (74%) and 48 did not fill (26%). Both reviewers correctly identified 136/136 cases of gallbladder filling. Reviewer A identified 47/48 cases of nonfilling and reviewer B identified 46/48 cases of nonfilling. Sensitivity and specificity were 100% and 98% for reviewer A and 100% and 96% for reviewer B, respectively.

CONCLUSION

The presence of excreted contrast in the gallbladder lumen can be determined using gadoxetate disodium-enhanced MRI without precontrast T1-weighted imaging.

Functional hepatobiliary MR imaging in children

BACKGROUND

Clinical application efforts for the hepatocyte-specific MRI contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) have mainly been directed toward detection and characterization of various hepatic masses in the adult population.

OBJECTIVE

Here we report our initial experience with Gd-EOB-DTPA for evaluating congenital and acquired hepatobiliary pathologies in the pediatric population.

MATERIALS AND METHODS

Twenty-one consecutive children receiving Gd-EOB-DTPA for functional hepatobiliary evaluation at our institution were retrospectively identified with IRB approval. The use of Gd-EOB-DTPA was classified in each case as definite, potential, or no clinical utility, focusing on the clinical value gained beyond traditional noncontrast fluid-sensitive MR cholangiopancreatography (FS-MRCP) and other imaging modalities.

RESULTS

Definite added value of Gd-EOB-DTPA was found in 12 patients, with potential value in 4 patients, and no value in 5 patients. Benefit was seen in cases of iatrogenic and non-iatrogenic biliary strictures, perihepatic fluid collections for biliary leak, hepatobiliary dysfunction in the absence of hyperbilirubinemia, and in the functional exclusion of cystic duct occlusion that can be seen in acute cholecystitis.

CONCLUSION

This is the first reported series of children with Gd-EOB-DTPA and this early work suggests potential pediatric applications.

Gadoxetate disodium-enhanced MRI of the liver: part 1, protocol optimization and lesion appearance in the noncirrhotic liver

OBJECTIVE

The purpose of this article is to review the pharmacokinetic and pharmacodynamic properties of gadoxetate disodium (Gd-EOB-DTPA), to describe a workflow-optimized pulse sequence protocol, and to illustrate the imaging appearance of focal lesions in the noncirrhotic liver.

CONCLUSION

Gd-EOB-DTPA allows a comprehensive evaluation of the liver with the acquisition of both dynamic and hepatocyte phase images. This provides potential additional information, especially for the detection and characterization of small liver lesions. However, protocol optimization is necessary for improved image quality and workflow.