[Value of MRCP for diagnosis of biliary complications after liver transplantation]

Small bowel transplant: state-of-the-art vascular and nonvascular imaging

BACKGROUND

Small bowel transplant (SBT) is a surgical procedure that may be used in patients with pathology resulting in severe intestinal failure resistant to conventional forms of surgical and nonsurgical treatment. Intestinal failure is defined as the failure of enterocytes to absorb sufficient macronutrients, water, and/or electrolytes to sustain homeostasis and/or promote growth. With the advancement of surgical techniques and advancements in perioperative transplant management, SBT has become an increasingly common treatment for intestinal failure, with survival rates for SBT comparable to those for other solid organ transplants.

MATERIALS AND METHODS

This review provides background on SBT, its variations, and the associated preoperative and postoperative imaging studies with regard to surgical planning and anticipated complications.

RESULTS AND CONCLUSIONS

With the increasing use of SBT, radiologists will be expected to be familiar with the diagnostic studies and available endovascular interventions associated with this procedure.

Role of MRCP in Diagnosing Biliary Anastomotic Strictures After Liver Transplantation: A Single Tertiary Care Center Experience

BACKGROUND

Biliary strictures (BS) are common complication after liver transplantation. We aimed to determine the accuracy of magnetic resonance cholagiopancreatography (MRCP) in diagnosing BS in liver transplant recipients (LTRs) when compared to direct cholangiographic methods (endoscopic resonance cholagiopancreatography [ERCP] and/or percutaneous transhepatic cholangiography [PTC]).

METHODS

Retrospective chart review of 910 LTRs (July 2008 to April 2015) was performed, and a total of 39 patients with duct-to-duct anastomosis (22 males; 56.4%; mean age, 52.8 ± 8.3 years) were included who had an MRCP followed by either ERCP and/or PTC within 4 weeks. A cholangiographic narrowing (on ERCP and/or PTC) that required balloon dilation and/or stent placement was considered a BS and was considered clinically significant if the intervention resulted in at least 30% improvement of bilirubin within 2 weeks. Sensitivity, specificity, accuracy, positive predictive values and negative predictive values of MRCP in diagnosing BS were calculated.

RESULTS

Magnetic resonance cholagiopancreatography showed anastomotic BS in 17 of 39 patients, and subsequent ERCP and/or PTC revealed a total of 25 BS (positive predictive value of 0.94). Nine BS on cholangiography (ERCP, 8; PTC, 1) were not detected on earlier MRCP (sensitivity, 0.64; 95% CI, 0.45-0.82); 2 were clinically significant BS and 6 of the remaining 7 had no improvement in their liver function test with biliary intervention. Thirteen LTRs had no BS on either modality (specificity, 0.93; 95% CI, 0.66-0.99). The negative predictive value of MRCP was 0.59 for cholangiographic BS. The overall accuracy of MRCP is 0.74 (exact 95% CI, 0.58-0.87). Inclusion of age, race, and alanine aminotransferase level improved the predictive value of MRCP (area under the curve = 0.94, 95% CI: 0.86-1.00).

CONCLUSIONS

Magnetic resonance cholagiopancreatography has high specificity but low sensitivity in diagnosing cholangiographic BS in LTRs, although the predictive value further improved with inclusion of age, race, and alanine aminotransferase. Clinical significance of BS in LTRs not identified on MRCP is questionable because ERCP with intervention did not improve their liver function tests in the vast majority.

Imaging of biliary complications in recipients of right-lobe living donor liver transplantation

Right-lobe living donor liver transplantation (RL-LDLT) is a common method devised in order to fulfill the demands of donor organ shortage in adult patients with end-stage liver diseases. However, biliary complications remain as the "Achilles' heel" of RL-LDLT, with wide variety of incidence among transplantation centers. Patients with biliary complications after RL-LDLT may have similar clinical presentations to those with other causes of graft dysfunction. Therefore, radiological evaluation plays a key role for differential diagnosis of such complications. In this article, we discuss the various methods of biliary reconstruction and imaging findings of common and uncommon biliary complications in recipients of RL-LDLT.

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.

Diagnosis and management of biliary complications in pediatric living donor liver transplant recipients

The incidence of biliary complications (BCs) after living donor liver transplantation (LDLT) can reach 40%. Published data on the pediatric population are limited, and treatment protocols vary. Our aim was to describe the clinical scenario for BCs and treatment approaches after LDLT. Between October 1995 and December 2012, 489 pediatric LDLT procedures were performed. BCs developed in 71 patients (14.5%). Biliary strictures (BSs) developed in 45 (9.2%) patients, and bile leaks (BLs) developed in 33 patients (6.7%). The BL diagnosis was clinical in all cases, and 69.7% of the patients underwent surgery. Nearly half of the BS cases had clinical features or suggestive ultrasound findings. Liver biopsy findings suggested BSs in 51.7%. Percutaneous transhepatic cholangiography was performed in 95.6% of the BS patients. The success rate was 77% [mean number of percutaneous biliary interventions (PBIs) = 3.9 ± 1.98, median drainage time = 8 months]. In conclusion, BL patients can be managed with conservative therapy, even though most of these patients will ultimately be treated with surgery. Diagnosing a BS requires a high degree of clinical suspicion because the available resources for its identification can fail in up to 50% of cases. A higher number of PBIs and the use of a drainage catheter for a longer time may be required to achieve better results with this technique.

Biliary complications after liver transplantation: addition of T1-weighted images to MR cholangiopancreatography facilitates detection of cast in biliary cast syndrome

PURPOSE

To evaluate the diagnostic performance of T2-weighted magnetic resonance (MR) cholangiopancreatography pulse sequences in comparison with MR cholangiopancreatography sequences combined with nonenhanced T1-weighted images in the detection of biliary cast syndrome in liver transplant recipients.

MATERIALS AND METHODS

This retrospective study was conducted in accordance with the declaration of Helsinki. Institutional review board approval was obtained. MR images in 95 patients who were examined after liver transplantation and who presented with symptoms of biliary obstruction were examined. Two separate sets of images, MR cholangiopancreatograms and MR cholangiopancreatograms plus T1-weighted images, were evaluated independently by three readers. Sensitivities, specificities, and positive and negative predictive values for biliary cast syndrome were calculated, and receiver operating characteristic curves were generated. The results of endoscopic retrograde cholangiopancreatography served as the reference standard. To determine interobserver agreement, κ values were calculated.

RESULTS

Cast appeared hyperintense on nonenhanced T1-weighted images. Sensitivities for T2-weighted MR cholangiopancreatography data alone were 0.65, 0.70, and 0.55 for the three readers. Adding unenhanced T1-weighted images resulted in sensitivities of 0.95, 0.90, and 0.90, respectively. Specificities for MR cholangiopancreatography alone and for MR cholangiopancreatography plus T1-weighted images were high on average (0.98, 0.97, and 0.97 vs 1.0 for all readers, respectively). Interobserver agreement was good for T2-weighted MR cholangiopancreatography (κ for readers 1 and 2 = 0.589, κ for readers 2 and 3 = 0.593, κ for readers 1 and 3 = 0.734) and was excellent for MR cholangiopancreatography plus T1-weighted images (κ for readers 1 and 2 = 0.806, κ for readers 2 and 3 = 0.881, κ for readers 1 and 3 = 0.848).

CONCLUSION

The combination of T2-weighted MR cholangiopancreatography and T1-weighted imaging yields higher diagnostic performance than MR cholangiopancreatography alone. Therefore, readers evaluating liver MR images with regard to biliary complications after liver transplantation should also look at the bile ducts on unenhanced T1-weighted images, as biliary cast might be more easily depicted on these images.

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.

Detection of biliary stenoses in patients after liver transplantation: is there a different diagnostic accuracy of MRCP depending on the type of biliary anastomosis?

PURPOSE

Two different forms of biliary anastomosis can be created in patients undergoing liver transplantation: (a) bilio-digestive anastomoses or (b) choledocho-choledochostomy. Aim of this study was to assess the accuracy of MR cholangiopancreatography (MRCP) for the depiction of biliary stenoses in liver transplant patients depending on the type of biliary anastomosis.

METHOD AND MATERIALS

24 liver transplant patients with clinical suspicion of biliary stenosis were studied (each 12 with bilio-digestive anastomosis/choledocho-choledochostomy). MRCP was performed on a 1.5 T scanner (Magnetom Avanto, Siemens) including 2D single shot RARE, 2D T2w HASTE, TrueFISP and 3D high-resolution navigator corrected sequences. Presence of (a) anastomotic stenoses (AST) and (b) NAS (non-anastomotic strictures) were assessed. Percutaneous transhepatic cholangiography (PTC) or endoscopic retrograde cholangiopancreatography (ERCP) were performed within 48h after MRCP and served as the standard of reference.

RESULTS

In patients with bilio-digestive anastomoses sensitivities of MRCP for the detection of AST and NAS amounted to 50% and 67%, respectively with specificity values of 83% and 50%. In patients with choledocho-chledochostomy sensitivities (AST: 100%, NAS: 100%) and specificities (AST: 100%, NAS: 88%) were significantly higher.

CONCLUSION

Biliary strictures after liver transplantation can be accurately detected by MRCP in patients after choledocho-chledochostomy. However, the diagnostic value of MRCP is lower if liver transplantation was performed in combination with a bilio-digestive anastomosis. This may be due to the less exact depiction of the anastomosis in the bowel wall. Thus, it is crucial to know the type of biliary anastomosis before choosing a diagnostic procedure.

Imaging in liver transplantation

The aim of this study was to illustrate the role of non-invasive imaging tools such as ultrasonography, multi-detector row computed tomography, and magnetic resonance imaging in the evaluation of pediatric and adult liver recipients and potential liver donors, and in the detection of potential complications arising from liver transplantation.