Biliary complications after orthotopic liver transplantation: MRCP findings

Radiologic findings of biliary complications post liver transplantation

Liver transplantation is a potentially curative treatment for patients with acute liver failure, end-stage liver disease, and primary hepatic malignancy. Despite tremendous advancements in surgical techniques and immunosuppressive management, there remains a high rate of post-transplant complications, with one of the main complications being biliary complications. In addition to anastomotic leak and stricture, numerous additional biliary complications are encountered, including ischemic cholangiopathy due to the sole arterial supply of the bile ducts, recurrence of primary biliary disease, infections, biliary obstruction from stones, cast, or hemobilia, and less commonly cystic duct remnant mucocele, vanishing duct syndrome, duct discrepancy and kinking, post-transplant lymphoproliferative disorder, retained stent, and ampullary dysfunction. This article presents an overview of biliary anatomy and surgical techniques in liver transplantation, followed by a detailed review of post-transplant biliary complications with their corresponding imaging findings on multiple modalities with emphasis on magnetic resonance imaging and MR cholangiopancreatography.

Magnetic Resonance Imaging of Liver Transplant

MR imaging increasingly has been adopted for follow-up imaging post-liver transplantation and for diagnosis of its complications. These include vascular and biliary complications as well as post-transplant malignancies. Interpretation of postoperative MR imaging should take into account the surgical technique and expected post-transplant changes. Contrast-enhanced MR imaging has high sensitivity for identification of vascular complications. MR cholangiopancreatography on the other hand is the most accurate noninvasive method for evaluation of biliary complications.

Diffusion tensor imaging of the abdominal organs: Influence of oriented intravoxel flow compartments

Water flow in partially oriented intravoxel compartments mimics an anisotropic fast-diffusion regime, which contributes to the signal attenuation in diffusion-weighted images. In the abdominal organs, this flow may reflect physiological fluid movements (eg, tubular urine flow in kidneys, or bile flow through the liver) and have a clinical relevance. This study investigated the influence of anisotropic intravoxel water flow on diffusion tensor imaging (DTI) of the abdominal organs. Diffusion-weighted images were acquired in five healthy volunteers using an EPI sequence with diffusion preparation (TR/TE: 1000 ms/71 ms; b-values: 0, 10, 20, 40, 70, 120, 250, 450, 700, 1000 s/mm² ; 12 noncollinear diffusion-encoding directions). DTI of liver and kidneys was performed assuming (i) monoexponential decay of the diffusion-weighted signal, and (ii) accounting for potential anisotropy of the fast-diffusion compartments using a tensorial generalization of the IVIM model. Additionally, potential dependency of the metrics of the tensors from the anatomical location was evaluated. Significant differences in the metrics of the diffusion tensor (DT) were found in both liver and kidneys when comparing the two models. In both organs, the trace and the fractional anisotropy of the DT were significantly higher in the monoexponential model than when accounting for perfusion. The comparison of areas of the liver proximal to the hilum with distal regions and of renal cortex with the medulla also proved a location dependency of the size of the fast-diffusion compartments. Pseudo-diffusion correction in DTI enables the assessment of the solid parenchyma regardless of the organ perfusion or other pseudo-diffusive fluid movements. This may have a clinical relevance in the assessment of parenchymal pathologies (eg, liver fibrosis). The fast pseudo-diffusion components present a detectable anisotropy, which may reflect the hepatic microcirculation or other sources of mesoscopic fluid movement in the abdominal organs.

Percutaneous Transhepatic Biliary Drainage for Biliary Stricture After Endotherapy Failure in Living Donor Liver Transplantation: A Single-Centre Experience from India

BACKGROUND

In the living donor liver transplant (LDLT) population, postoperative biliary stricture is a common problem. Endoscopic retrograde cholangiography (ERCP) and stenting failures usually occur because of odd angulation of the ducts, particularly in right lobe grafts. Percutaneous transhepatic biliary drainage (PTBD) is helpful in patients where endoscopic intervention is unsuccessful. We report our experience in this particular group of patients from India.

METHODS

We analysed retrospective data of 932 patients who underwent LDLT at our centre. Data collected include basic demographics, technical and clinical success rate of PTBD, postprocedure complications and overall outcome.

RESULTS

Of the 932 patients, 81 (8.7%) developed biliary stricture and required endoscopic or percutaneous interventions; out of whom, 75 patients underwent ERCP, and 6 patients had hepaticojejunostomy. Right posterior sector graft recipients had the highest incidence of biliary stricture (29.16%), followed by the right lobe grafts (8.57%), whereas stricture rate was less among left lobe and left lateral lobe graft recipients (3.77% and 3.7%, respectively). Failure of ERCP was common among the ductoplasty group (80%). The failure rate of ERCP did not differ significantly among patients who had single-duct, two-duct or three-duct anastomoses (44%, 36% and 50%, respectively, p > 0.05). PTBD was technically successful in 34 patients (87%) The mortality rate following PTBD was 2.5%, and morbidity was 15%. For the 5 patients in whom PTBD could not be performed, open hepaticojejunostomy was performed successfully.

CONCLUSIONS

Right lobe liver grafts have high incidence of biliary stricture compared with left lobe grafts. The failure of ERCP was not dependent on the number of biliary anastomoses; however, the ductoplasty group had a higher failure rate. PTBD is technically successful in a majority of patients albeit with a morbidity of 15%. Open hepaticojejunostomy is a good therapeutic option following PTBD failure.

Imaging of liver transplantation

Liver transplantation (LT) is the treatment of choice for end-stage chronic liver disease, fulminant liver failure and early stage hepatocellular carcinoma. As discussed in this review, state-of-the-art imaging modalities including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) play a pivotal role in the selection of patients and donors, as well as in early detection of those complications at risk of impairing graft function and/or survival. We also illustrate main imaging findings related to the wide spectrum of clinical problems raised by LT.

Incidence and Treatment of Bile Stones After Liver Transplant

OBJECTIVES

Although the incidence of bile stones after liver transplant is rare (2%-6%), various complications can occur, including recurrent cholangitis, biliary strictures, graft loss, and patient mortality.

MATERIALS AND METHODS

We retrospectively evaluated bile stone incidence, pathogenesis, and treatment in 352 liver transplant recipients, comparing demographics, transplant indication, blood lipid profile, bile reconstruction technique, postoperative complications, time of diagnosis, and treatment regimens.

RESULTS

Of 352 recipients, 18 had bile stones, with 13 of these patients (72.2%) receiving duct-to-duct bile reconstruction, 17 having biliary complications before bile stone development, 7 (38.9%) having biliary stricture, 6 (33.3%) having biliary leakage, 4 (22.2%) having biliary strictures secondary to biliary leakage, and 7 (38.9%) having hepatic artery complications early posttransplant. Previous biliary complications and recurrent cholangitis significantly increased bile stones. Incidence in patients with triglyceride levels > 250 mg/dL was significantly different from those with levels at < 250 mg/dL. Cold ischemia time was significant in those with and without bile stones (P = .001). Three patients (16%) were treated by endoscopic tools, with others (15/18, 84%) treated via percutaneous procedures.

CONCLUSIONS

Bile stone risk can be greater in those with previous biliary complications, hepatic artery problems, long cold ischemia time, and high cholesterol levels. It can be successfully treated by endoscopic and percutaneous techniques.

Contrast-Enhanced Magnetic Resonance Cholangiography: Practical Tips and Clinical Indications for Biliary Disease Management

Since its introduction, MRCP has been improved over the years due to the introduction of several technical advances and innovations. It consists of a noninvasive method for biliary tree representation, based on heavily T2-weighted images. Conventionally, its protocol includes two-dimensional single-shot fast spin-echo images, acquired with thin sections or with multiple thick slabs. In recent years, three-dimensional T2-weighted fast-recovery fast spin-echo images have been added to the conventional protocol, increasing the possibility of biliary anatomy demonstration and leading to a significant benefit over conventional 2D imaging. A significant innovation has been reached with the introduction of hepatobiliary contrasts, represented by gadoxetic acid and gadobenate dimeglumine: they are excreted into the bile canaliculi, allowing the opacification of the biliary tree. Recently, 3D interpolated T1-weighted spoiled gradient echo images have been proposed for the evaluation of the biliary tree, obtaining images after hepatobiliary contrast agent administration. Thus, the acquisition of these excretory phases improves the diagnostic capability of conventional MRCP—based on T2 acquisitions. In this paper, technical features of contrast-enhanced magnetic resonance cholangiography are briefly discussed; main diagnostic tips of hepatobiliary phase are showed, emphasizing the benefit of enhanced cholangiography in comparison with conventional MRCP.

Comparison of gadoxetic acid to gadobenate dimeglumine for assessment of biliary anatomy of potential liver donors

PURPOSE

To compare MRI using gadobenate dimeglumine (Gd-BOPTA) vs. gadoxetic acid disodium (Gd-EOB-DTPA) for the assessment of biliary anatomy of potential liver donors.

METHODS

76 potential liver donors (39 M/37 F, mean 38 years) who underwent 1.5T MRI using Gd-BOPTA (n = 37) or Gd-EOB-DTPA (n = 39) were retrospectively evaluated. T2 cholangiogram (T2 MRC) and delayed hepatobiliary phase (HBP) T1 cholangiogram (T1 MRC) (performed during HBP 20 min after injection of Gd-EOB-DTPA and 1-2 h after Gd-BOPTA injection) were obtained in addition to MR angiogram/venogram. Two independent observers evaluated image quality (IQ) and conspicuity scores (CS) of the biliary system. Biliary anatomy was assessed in 3 reading sessions (T2 MRC, T1 MRC, and combined T2/T1 MRC). Reference standard consisted of consensus reading of two separate observers of all image sets, clinical/surgical information and intraoperative cholangiogram when available. Datasets were compared using the Mann-Whitney U test or Chi-squared test.

RESULTS

There was no difference in IQ for T1 MRC using either contrast agent or T2 MRC vs. T1 MRC for both observers (all p values >0.07). There was superior CS for T2 MRC vs. Gd-BOPTA T1 MRC for both observers and T2 MRC vs. Gd-EOB for one observer (p < 0.001). No difference was found for biliary variant detection for T1 MRC (with either contrast agent) vs. T2 MRC. Combined T2/T1 MRC demonstrated improved sensitivity for biliary variant detection using Gd-BOPTA for both observers (p < 0.004) and Gd-EOB-DTPA for one observer (p < 0.001).

CONCLUSION

Equivalent image quality was found for T1 MRC obtained with Gd-BOPTA or Gd-EOB-DTPA and T2 MRC. T1 MRC is equivalent to T2 MRC for detection of variant biliary anatomy, and the combination of sequences may have added value.

Imaging follow-up after liver transplantation

Liver transplantation (LT) represents the best treatment for end-stage chronic liver disease, acute liver failure and early stages of hepatocellular carcinoma. Radiologists should be aware of surgical techniques to distinguish a normal appearance from pathological findings. Imaging modalities, such as ultrasound, CT and MR, provide for rapid and reliable detection of vascular and biliary complications after LT. The role of imaging in the evaluation of rejection and primary graft dysfunction is less defined. This article illustrates the main surgical anastomoses during LT, the normal appearance and complications of the liver parenchyma and vascular and biliary structures.

Risk factors of biliary intervention by imaging after living donor liver transplantation

AIM: To determine the risk factors of biliary intervention using magnetic resonance cholangiopancreatography (MRCP) after living donor liver transplantation (LDLT).

METHODS: We retrospectively enrolled 196 patients who underwent right lobe LDLT between 2006 and 2010 at a single liver transplantation center. Direct duct-to-duct biliary anastomosis was performed in all 196 patients. MRCP images routinely taken 1 mo after LDLT were analyzed to identify risk factors for biliary intervention during follow-up, such as retrograde cholangiopancreatography or percutaneous transhepatic biliary drainage. Two experienced radiologists evaluated the MRCP findings, including the anastomosis site angle on three-dimensional images, the length of the filling defect on maximum intensity projection, bile duct dilatation, biliary stricture, and leakage.

RESULTS: Eighty-nine patients underwent biliary intervention during follow-up. The anastomosis site angle [hazard ratio (HR) = 0.48; 95% confidence interval (CI), 0.30-0.75, P < 0.001], a filling defect in the anastomosis site (HR = 2.18, 95%CI: 1.41-3.38, P = 0.001), and biliary leakage (HR = 2.52, 95%CI: 1.02-6.20, P = 0.048) on MRCP were identified in the multivariate analysis as significant risk factors for biliary intervention during follow-up. Moreover, a narrower anastomosis site angle (i.e., below the median angle of 113.3°) was associated with earlier biliary intervention (38.5 ± 4.2 mo vs 62. 1 ± 4.1 mo, P < 0.001). Kaplan-Meier analysis comparing biliary intervention-free survival according to the anastomosis site angle revealed that lower survival was associated with a narrower anastomosis site angle (36.3% vs 62.0%, P < 0.001).

CONCLUSION: The biliary anastomosis site angle in MRCP after LDLT may be associated with the need for biliary intervention.

Hollow organ abdominal ischemia, part II: clinical features, etiology, imaging findings and management

Acute hollow organ ischemia commonly presents with acute pain prompting radiologic evaluation and almost always requires urgent treatment. Despite different risk factors and anatomic differences, ischemia is commonly due to low flow states but can also be due to arterial and venous occlusion. Radiologic diagnosis is critical as many present with nonspecific symptoms. Contrast-enhanced computed tomography (CT) is the modality of choice. Magnetic resonance imaging (MRI) is preferred in suspected appendicitis in pregnant patients and is superior in biliary necrosis. This article provides a pictorial review of the CT/MRI features of hollow abdominal organ ischemia while highlighting key clinical features, pathogenesis, and management.

Biliary imaging: multimodality approach to imaging of biliary injuries and their complications

Although traumatic and iatrogenic bile leaks are rare, they have become more prevalent in recent years due to an increased propensity toward nonsurgical management of patients with liver trauma and an overall increase in the number of hepatobiliary surgeries being performed. Because clinical signs and symptoms of bile leaks are nonspecific and delay in the recognition of bile leaks is associated with high morbidity and mortality rates, imaging is crucial for establishing an early diagnosis and guiding the treatment algorithm. At computed tomography or ultrasonography, free or contained peri- or intrahepatic low-attenuation (low-density) fluid in the setting of recent trauma or hepatobiliary surgery should raise suspicion for a bile leak. Hepatobiliary scintigraphy and magnetic resonance (MR) cholangiopancreatography with hepatobiliary contrast agents can help detect active or contained bile leaks. MR cholangiopancreatography with hepatobiliary contrast agents has the added advantage of being able to help localize the bile leak, which in turn can help determine if endoscopic management is sufficient or if surgical management is warranted. Endoscopic retrograde cholangiopancreatography may provide diagnostic confirmation and concurrent therapy when nonsurgical management is pursued. A multimodality imaging approach is helpful in diagnosing traumatic or iatrogenic biliary injuries, accurately localizing a bile leak, and determining appropriate treatment.

Role of multi-detector computed tomography for biliary complications after liver transplantation

AIM: To investigate the diagnostic performance of multi-detector computed tomography (MDCT) in detecting biliary complications after orthotopic liver transplantation (OLT).

METHODS: Eighty-three consecutive OLT recipients, who presented with clinical or biochemical signs of biliary complications, underwent MDCT examination. Two experienced radiologists assessed MDCT images in consensus to determine biliary complications. Final confirmation was based on percutaneous transhepatic cholangiography or endoscopic retrograde cholangiography in 58 patients, surgery in four patients, liver biopsy in 10, and clinical and sonography follow-up in 11 patients.

RESULTS: Biliary complications were eventually confirmed in 62 of 83 patients (74.7%), including anastomotic biliary strictures in 32, nonanastomotic biliary strictures in 21, biliary stones in nine (5 with biliary strictures), anastomotic bile leak in five, and biloma in six (all with nonanastomotic strictures, and 2 with biligenic hepatic abscess). Twenty-one patients had no detection of biliary complications. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of MDCT for detecting biliary strictures were 90.6%, 86.7%, 89.2%, 92.3% and 83.9%, respectively. For detecting biliary stones, anastomotic bile leak and biloma, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of MDCT were all 100%.

CONCLUSION: MDCT is a useful screening tool for detecting biliary complications after OLT.

Postoperative biliary adverse events following orthotopic liver transplantation: Assessment with magnetic resonance cholangiography

Biliary adverse events following orthotopic liver transplantation (OLT) are relatively common and continue to be serious causes of morbidity, mortality, and transplant dysfunction or failure. The development of these adverse events is heavily influenced by the type of anastomosis during surgery. The low specificity of clinical and biologic findings makes the diagnosis challenging. Moreover, direct cholangiographic procedures such as endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography present an inadmissible rate of adverse events to be utilized in clinically low suspected patients. Magnetic resonance (MR) maging with MR cholangiopancreatography is crucial in assessing abnormalities in the biliary system after liver surgery, including liver transplant. MR cholangiopancreatography is a safe, rapid, non-invasive, and effective diagnostic procedure for the evaluation of biliary adverse events after liver transplantation, since it plays an increasingly important role in the diagnosis and management of these events. On the basis of a recent systematic review of the literature the summary estimates of sensitivity and specificity of MR cholangiopancreatography for diagnosis of biliary adverse events following OLT were 0.95 and 0.92, respectively. It can provide a non-invasive method of imaging surgical reconstruction of the biliary anastomoses as well as adverse events including anastomotic and non-anastomotic strictures, biliary lithiasis and sphincter of Oddi dysfunction in liver transplant recipients. Nevertheless, conventional T2-weighted MR cholangiography can be implemented with T1-weighted contrast-enhanced MR cholangiography using hepatobiliary contrast agents (in particular using Gd-EOB-DTPA) in order to improve the diagnostic accuracy in the adverse events’ detection such as bile leakage and strictures, especially in selected patients with biliary-enteric anastomosis.

Magnetic resonance cholangiography in the assessment and management of biliary complications after OLT

Despite advances in patient and graft management, biliary complications (BC) still represent a challenge both in the early and delayed period after orthotopic liver transplantation (OLT). Because of unspecific clinical presentation, imaging is often mandatory in order to diagnose BC. Among imaging modalities, magnetic resonance cholangiography (MRC) has gained widespread acceptance as a tool to represent the reconstructed biliary tree noninvasively, using both the conventional technique (based on heavily T2-weighted sequences) and contrast-enhanced MRC (based on the acquisition of T1-weighted sequences after the administration of hepatobiliary contrast agents). On this basis, MRC is generally indicated to: (1) avoid unnecessary procedures of direct cholangiography in patients with a negative examination and/or identify alternative complications; and (2) provide a road map for interventional procedures or surgery. As illustrated in the review, MRC is accurate in the diagnosis of different types of biliary complications, including anastomotic strictures, non-anastomotic strictures, leakage and stones.

Post-operative imaging in liver transplantation: State-of-the-art and future perspectives

Orthotopic liver transplantation (OLT) represents a major treatment for end-stage chronic liver disease, as well as selected cases of hepatocellular carcinoma and acute liver failure. The ever-increasing development of imaging modalities significantly contributed, over the last decades, to the management of recipients both in the pre-operative and post-operative period, thus impacting on graft and patients survival. When properly used, imaging modalities such as ultrasound, multidetector computed tomography, magnetic resonance imaging (MRI) and procedures of direct cholangiography are capable to provide rapid and reliable recognition and treatment of vascular and biliary complications occurring after OLT. Less defined is the role for imaging in assessing primary graft dysfunction (including rejection) or chronic allograft disease after OLT, e.g., hepatitis C virus (HCV) recurrence. This paper: (1) describes specific characteristic of the above imaging modalities and the rationale for their use in clinical practice; (2) illustrates main imaging findings related to post-OLT complications in adult patients; and (3) reviews future perspectives emerging in the surveillance of recipients with HCV recurrence, with special emphasis on MRI.

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.

MRI for evaluation of potential living liver donors: a new approach including contrast-enhanced magnetic resonance cholangiography

OBJECTIVES

To assess the feasibility of a comprehensive MRI protocol using intrabiliary contrast medium (gadolinium-EOB-DTPA) for evaluation of living liver donors.

MATERIAL AND METHODS

In this prospective study, 30 donor candidates for living-related liver transplantation (17 men; 13 women, mean age 37 ± 10.9 years) underwent MRI including MR-angiography (MRA) as well as a conventional T2-weighted MR-cholangiography (MRC) and a contrast-enhanced sequence for depiction of the biliary structures. MRC and MRA images were evaluated for quality on a four-point-scale (score of 0 indicated poor and a score of 3, excellent image quality). Anatomic variants of the arterial, venous, portal venous, and biliary structures were identified.

RESULTS

Image quality was diagnostic in all examinations except for 4 of 30 MRA data sets. Intrahepatic biliary structures, especially with regard to the intrahepatic bile ducts of 2nd and 3rd order could be identified with significantly increased image quality than in conventional T2-weighted MRC sequences (P = 0.005 and P = 0.035). A high percentage rate of anatomic variants regarding the biliary, arterial, venous, and portal venous anatomy was found.

CONCLUSION

This protocol allows the evaluation of liver donors especially with regard to the biliary structures. However, the depiction of the arterial anatomy requires further technical developments.

Debris-filled biliary system: a difficult diagnosis on MRI and MRCP

We describe a debris-filled biliary system as a difficult diagnosis using magnetic resonance imaging and magnetic resonance cholangiopancreatography (MRCP). A male patient aged 60 years showed a nonvisualized biliary system due to complete filling with debris. The following imaging features were observed: mild heterogeneity of intermediate signal on T2-weighted, MRCP and T1-weighted images and mild heterogeneous enhancement of periportal tissue on early and late postcontrast images. The absence of simple-appearing bile on T2 or MRCP images made the diagnosis of dilated, debris-filled biliary system challenging.

Degree of bile-duct dilatation in liver-transplanted patients with biliary stricture: a magnetic resonance cholangiography-based study

PURPOSE

This study assessed whether the degree of bile-duct dilatation in liver-transplanted patients is correlated with the time from intervention and the type of underlying biliary stricture.

METHODS AND MATERIALS

Fifty-seven 3D magnetic resonance cholangiograms (MRCs) performed on 42 liver-transplanted patients were retrospectively evaluated. Diameter was measured at the level of the extrahepatic bile duct (EBD), right hepatic duct (RHD), left hepatic duct (LHD), anterior and posterior right hepatic ducts (aRHD, pRHD) and left lateral and medial ducts (LLD, LMD). Data were stratified according to the type of biliary stricture (all types, anastomotic, ischaemic-like, mixed) and compared, on a per-examination basis: (a) between two groups based on time from transplantation using a 1-year threshold (nonlongitudinal analysis); (b) among 26 repeated examinations on 11 patients (longitudinal analysis); (c) among different stricture groups.

RESULTS

The biliary tree was slightly dilated within 1 year from transplantation (2.9±1.3 to 6.1±3.2 mm). In general, nonlongitudinal analysis showed minimally larger duct size after 1 year (mean +1.4±0.5 mm) despite significant differences at most sites of measurement considering all types of strictures (p<0.01; Mann-Whitney U test). Longitudinal analysis showed diameter increase over time, although without statistically significant differences (p>0.01; Kruskal-Wallis test). No significant difference in bile-duct size was observed when comparing types of stricture (p>0.01; Kruskal-Wallis test).

CONCLUSIONS

Biliary dilatation after liver transplantation is mild and develops slowly regardless of the underlying type of stricture, possibly in relation to graft properties. MRC has a potential role as first-line imaging modality for a reliable assessment of biliary dilatation and the presence of a stricture.

Role of magnetic resonance imaging in the detection of anastomotic biliary strictures after liver transplantation

INTRODUCTION

Biliary complications after orthotopic liver transplantation (OLT) are the principal cause of morbidity and graft dysfunction, ranging in incidence from 5.8% to 30% of cases. Biliary strictures are the most frequent type of late complication. The aim of this study was to evaluate the role of magnetic resonance cholangiography (MRC) to detect biliary anastomotic strictures among patients undergone OLT with abnormal liver function tests.

MATERIALS AND METHODS

One hundred twenty-one of 300 patients who underwent OLT were evaluated by MRC for clinically suspected anastomotic biliary strictures. In all patients, we performed various precholangiographic sequences including T1- and T2-weighted and MRC (radial SE 2D and SS-TSE 3D). Magnetic resonance imaging findings were subdivided as absence or presence of an anastomotic stricture. Diagnostic confirmation was obtained by endoscopic retrograde cholangiography (n=32), percutaneous transhepatic cholangiography (n=21) or surgical treatment (n=18).

RESULTS

MRC detected 56 anastomotic biliary strictures, 53 of which were confirmed by other imaging modalities. MRC showed two false-negative cases and three false-positive cases. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRC to detect biliary strictures were 96%, 96%, 95%, 97%, and 96%, respectively.

CONCLUSION

MRC proved to be a reliable noninvasive technique to visualize the biliary anastomosis and depict biliary strictures after OLT. MRC should be used when a biliary anastomotic stricture is suspected in an OLT patient.

Impact of magnetic resonance cholangiography in managing liver-transplanted patients: preliminary results of a clinical decision-making study

PURPOSE

This study was performed to assess the role of magnetic resonance cholangiography (MRC) in the clinical decision-making process of referring physicians when managing liver-transplanted patients.

MATERIALS AND METHODS

Over a 6-month period, 21 liver-transplanted patients with a suspected biliary complication were referred for MRC. Referring physicians were asked to prospectively state, before and after MRC, the leading diagnosis; the level of confidence (on a 0-100% scale); the most appropriate diagnostic/therapeutic plan. Data analysis assessed was the diagnostic yield of MRC; the proportion of change in the leading diagnosis; the therapeutic efficacy (i.e. proportion of change in the initial diagnostic/therapeutic plan); the diagnostic thinking efficacy (i.e., gain in diagnostic confidence). Statistical significance was assessed with the Mann-Whitney U test. MRC accuracy was also calculated.

RESULTS

Data analysis showed a diagnostic yield of 85.7%; a proportion of change in leading diagnosis of 19.0%; a therapeutic efficacy of 42.8%; a diagnostic thinking efficacy for concordant and discordant leading diagnoses of 18.8% and 78.7%, respectively (p<0.01). MRC accuracy was 92.3%.

CONCLUSIONS

MRC significantly increased the diagnostic confidence, irrespective of the concordance between pre- and posttest diagnoses. Moreover, MRC determined a change in patient management in a significant proportion of cases, leading to clinical benefits.

Diffusion-weighted MRI of the transplanted liver

AIM

To assess the value of diffusion-weighted imaging (DWI) in evaluating parenchymal disorders following orthotopic liver transplantation (OLT).

MATERIALS AND METHODS

This institutional review board-approved, retrospective study measured the hepatic apparent diffusion coefficients (ADC) in patients following OLT. Those with vascular complications or within 3 months of OLT were excluded. A single-shot echoplanar sequence with b values of 50, 400 (or 500), and 800 s/mm(2) was performed. Liver biopsy specimens [performed with a median of 17 days after magnetic resonance imaging (MRI)] were recorded for the presence and severity of parenchymal disorders, such as acute cellular rejection, and recurrence of fibrosis in all patients, and the recurrence of viral hepatitis in patients with hepatitis C. ADC values were measured blinded to histology in 41 patients (33 males) who had 56 MRI scans.

RESULTS

There was a significant difference in ADC values associated with a histological abnormality seen on core biopsy [n=43, mean (SD) ADC of 0.91 (0.15)×10(-3) mm(2)/s] and those associated with no histological abnormality [n=13, mean (SD) ADC of 1.11 (0.17)×10(-3) mm(2)/s; (p=0.003)]. ADC values did not predict any of the individual parenchymal disorders on logistic regression analysis. When the ADC value was <0.99×10(-3) mm(2)/s, there was a sensitivity and specificity of 85% and 72%, respectively, in predicting a parenchymal disorder (area under ROC curve=0.84; 95% CI 0.72 to 0.92).

CONCLUSION

ADC measurements may help in deciding which patients require core liver biopsy after OLT. However, ADC values are not likely to be reliable in differentiating between the various parenchymal disorders.

Is MRCP equivalent to ERCP for diagnosing biliary obstruction in orthotopic liver transplant recipients? A meta-analysis

BACKGROUND

Biliary complications are the second leading cause of morbidity and mortality in orthotopic liver transplant (OLT) recipients. Endoscopic retrograde cholangiography (ERC) is considered the diagnostic criterion standard for post-orthotopic liver transplantation biliary obstruction, but incurs significant risks.

OBJECTIVE

To determine the diagnostic accuracy of MRCP for biliary obstruction in OLT patients.

DESIGN

A systematic literature search identified studies primarily examining the utility of MRCP in detecting post-orthotopic liver transplantation biliary obstruction. A meta-analysis was then performed according to the Quality of Reporting Meta-Analyses statement.

SETTING

Meta-analysis of 9 studies originally performed at major transplantation centers.

PATIENTS

A total of 382 OLT patients with clinical suspicion of biliary obstruction.

INTERVENTIONS

MRCP and ERCP or clinical follow-up.

MAIN OUTCOME MEASUREMENTS

Sensitivity and specificity of MRCP for diagnosis of biliary obstruction.

RESULTS

The composite sensitivity and specificity were 0.96 (95% CI, 0.92-0.98) and 0.94 (95% CI, 0.90-0.97), respectively. The positive and negative likelihood ratios were 17 (95% CI, 9.4-29.6) and 0.04 (95% CI, 0.02-0.08), respectively.

LIMITATIONS

All but 1 included study had significant design flaws that may have falsely increased the reported diagnostic accuracy.

CONCLUSIONS

The high sensitivity and specificity demonstrated in this meta-analysis suggest that MRCP is a promising test for diagnosing biliary obstruction in patients who have undergone liver transplantation. However, given the significant design flaws in most of the component studies, additional high-quality data are necessary before unequivocally recommending MRCP in this setting.

Magnetic resonance cholangiopancreatography for the accurate diagnosis of biliary complications after liver transplantation: comparison with endoscopic retrograde cholangiography and percutaneous transhepatic cholangiography - long-term follow-up

Biliary complications after liver transplantation remain a serious cause of morbidity and mortality. Direct invasive cholangiographic techniques, endoscopic retrograde cholangiography (ERCP) or percutaneous transhepatic cholangiography (PTC), have procedure-related complications. Magnetic resonance cholangiopancreatography (MRCP) is non-invasive, safe, and accurate. The aim of this study was to evaluate MRCP in detecting biliary complications following liver transplantation and comparing findings with ERCP and PTC. Twenty-seven consecutive liver transplant recipients who presented with clinical and biochemical, ultrasonographic, or histological evidence of biliary complications were evaluated with MRCP. Patients were followed up for a median period of 36 months. The presence of a biliary complication was confirmed in 18 patients (66.6%): anastomotic biliary stricture in 12 (66.6%); diffuse intrahepatic biliary stricture in 5 (27.7%): ischemic (n = 3), recurrence of primary sclerosing cholangitis (n = 2), and choledocholithiasis in one. In nine patients (33.3%), MRCP was normal. Six patients underwent ERCP, and eight PTC. There was a statistically significant correlation between the MRCP and both ERCP and PTC (p = 0.01) findings. The sensitivity and specificity of the MRCP were 94.4% and 88.9%, respectively, and the positive and negative predictive values, 94.4% and 89.9%, respectively. MRCP is an accurate imaging tool for the assessment of biliary complications after liver transplantation. We recommend that MRCP be the diagnostic imaging modality of choice in this setting, reserving direct cholangiography for therapeutic procedures.

Gadolinium-enhanced imaging of liver tumors and manifestations of hepatitis: pharmacodynamic and technical considerations

The ability for contrast-enhanced magnetic resonance imaging to provide significant diagnostic impact to focal and diffuse liver diseases requires knowledge, analysis, and technical optimization of the imaging techniques. Our review outlines the technical requirements needed to perform reproducible contrast-enhanced liver imaging and describes the important imaging features for assessing liver disease with conventional and alternate gadolinium-based contrast media. We present an experimental review of timing and quantification methods in dynamic contrast-enhanced liver imaging, with results of analysis showing perfusion and uptake curves in a series of patients and healthy subjects. An evidence-based methodology for reproducible arterial-phase imaging is detailed for performing a real-time bolus-tracking method. Additional diagnostic imaging features manifest at later imaging phases, in which the kinetic behavior of the contrast media serves to further specify focal lesions, while revealing detailed information of diffuse liver disease, particularly hepatic fibrosis. We review the utility of alternate gadolinium-based contrast media that undergo hepatocyte uptake, for applications related to liver tumor imaging. We also introduce results showing the potential for using alternate hepatocyte uptake agents to detect and quantify liver changes related to acute and chronic hepatitides.