MR imaging as the sole preoperative imaging modality for right hepatectomy: a prospective study of living adult-to-adult liver donor candidates

Precision Mapping of Intrahepatic Biliary Anatomy and Its Anatomical Variants Having a Normal Liver Using 2D and 3D MRCP

Despite significant advances in hepatobiliary surgery, biliary injury and leakage remain typical postoperative complications. Thus, a precise depiction of the intrahepatic biliary anatomy and anatomical variant is crucial in preoperative evaluation. This study aimed to evaluate the precision of 2D and 3D magnetic resonance cholangiopancreatography (MRCP) in exact mapping of intrahepatic biliary anatomy and its variants anatomically in subjects with normal liver using intraoperative cholangiography (IOC) as a reference standard. Thirty-five subjects with normal liver activity were imaged via IOC and 3D MRCP. The findings were compared and statistically analyzed. Type I was observed in 23 subjects using IOC and 22 using MRCP. Type II was evident in 4 subjects via IOC and 6 via MRCP. Type III was observed equally by both modalities (4 subjects). Both modalities observed type IV in 3 subjects. The unclassified type was observed in a single subject via IOC and was missed in 3D MRCP. Accurate detection by MRCP of intrahepatic biliary anatomy and its anatomical variants was made in 33 subjects out of 35, with an accuracy of 94.3% and a sensitivity of 100%. In the remaining two subjects, MRCP results provided a false-positive pattern of trifurcation. MRCP competently maps the standard biliary anatomy.

Effects of laparoscopy, laparotomy, and respiratory phase on liver volume in a live porcine model for liver resection

Background

Hepatectomy, living donor liver transplantations and other major hepatic interventions rely on precise calculation of the total, remnant and graft liver volume. However, liver volume might differ between the pre- and intraoperative situation. To model liver volume changes and develop and validate such pre- and intraoperative assistance systems, exact information about the influence of lung ventilation and intraoperative surgical state on liver volume is essential.

Methods

This study assessed the effects of respiratory phase, pneumoperitoneum for laparoscopy, and laparotomy on liver volume in a live porcine model. Nine CT scans were conducted per pig (N = 10), each for all possible combinations of the three operative (native, pneumoperitoneum and laparotomy) and respiratory states (expiration, middle inspiration and deep inspiration). Manual segmentations of the liver were generated and converted to a mesh model, and the corresponding liver volumes were calculated.

Results

With pneumoperitoneum the liver volume decreased on average by 13.2% (112.7 ml ± 63.8 ml, p < 0.0001) and after laparotomy by 7.3% (62.0 ml ± 65.7 ml, p = 0.0001) compared to native state. From expiration to middle inspiration the liver volume increased on average by 4.1% (31.1 ml ± 55.8 ml, p = 0.166) and from expiration to deep inspiration by 7.2% (54.7 ml ± 51.8 ml, p = 0.007).

Conclusions

Considerable changes in liver volume change were caused by pneumoperitoneum, laparotomy and respiration. These findings provide knowledge for the refinement of available preoperative simulation and operation planning and help to adjust preoperative imaging parameters to best suit the intraoperative situation.

Prevalence of Different Hepatobiliary Tree Variants on Magnetic Resonance Cholangiopancreatography in Patients Visiting a Tertiary Care Teaching Hospital in Karachi

Introduction

Hepatobiliary tree variant anatomy is crucial to understand the preoperative planning of hepatobiliary surgeries. Although the presence of variant anatomy is not an absolute contraindication for liver transplantation, inadvertent mapping can lead to postoperative biliary complications. These variants are also important to be recognized in various hepatobiliary surgeries and interventional procedures. Magnetic resonance cholangiopancreatography (MRCP) is an excellent non-invasive imaging tool that can identify biliary anatomy. The purpose of the current study is focused on determining anatomical variants of the biliary tree on MRCP in our population visiting a teaching hospital in Karachi.

Methods

This cross-sectional study was conducted on patients referred to Dr. Ziauddin Hospital for MRCP. MRCP was performed on MAGNETOM Avanto, SIEMENS, Belgium, Germany. Images were analyzed on a workstation by two radiologists and a postgraduate trainee. A senior radiologist reviewed equivocal cases. SPSS 22.0 (SPSS Inc., Chicago, IL) was used for statistical analysis. Chi-square test was used to see the link between anatomical variants of biliary tree and gender. P-value of ≤0.05 was considered as statistically significant.

Results

We recruited 369 patients undergoing MRCP consecutively for our study. Out of 369, 342 patients were eligible for analysis (139 males and 203 females). Standard anatomy was found to be prevalent in 65.8%. Type 3 was the leading variant. A statistically significant difference was recorded for the type 2 anatomic variant which was more frequent in males than females (p-value <0.001), while types 1, 3, and 4 anatomic variants were found to be more in females than males but this difference was not statistically significant. Few other variants were also recorded.

Conclusion

This study is robust evidence regarding biliary variants in Pakistan. It is important to consider these variants in our region, owing to an increased trend of liver transplants and other hepatobiliary procedures.

High spatial resolution navigated 3D T1-weighted hepatobiliary MR cholangiography using Gd-EOB-DTPA for evaluation of biliary anatomy in living liver donors

PURPOSE

To determine the feasibility of high-resolution navigated three-dimensional (3D) T1-weighted hepatobiliary MR cholangiography (Nav T1 MRC) using Gd-EOB-DTPA for biliary visualization in living liver donors and to assess added value of 3D T1-weighted hepatobiliary MRCs in improving the confidence and diagnostic accuracy of biliary anatomy in complementary to T2-weighted MRCs.

METHODS

Twenty-nine right liver donors underwent 3D T2 MRC, 2D T2 MRC, breath-hold T1-weighted hepatobiliary MRC (BH T1 MRC), and Nav T1 MRC. Two readers independently reviewed and compared 3D/2D MRC set, added BH T1 MRC set, and added Nav T1 MRC set for biliary diagnostic accuracy and confidence. For each MRC, biliary segments visualization and image quality were scored.

RESULTS

Both BH T1 MRC and Nav T1 MRC improved accuracy and specificity in biliary diagnosis when added to 3D/2D T2 MRC-alone set, though without statistical significance (R1, 82.8% to 93.1%; R2, 82.8% to 89.7%). The added Nav T1 MRC set showed the highest diagnostic confidence with both readers. Both readers scored Nav T1 MRC with the highest visualization scores for branching ducts and overall ducts.

CONCLUSION

Combining T1-weighted hepatobiliary MRCs to 3D/2D T2 MRC set improved accuracy for biliary anatomy diagnosis; time-efficient BH T1 MRC in axial and coronal planes should be considered as a key MRC sequence complementary to T2 MRCs. Given excellent biliary visualization and superior diagnostic confidence, Nav T1 MRC in selected subjects with breath-hold difficulties and inconclusive or complex biliary variations may assist in reaching a correct biliary diagnosis.

Mapping of hepatic vasculature in potential living liver donors: comparison of gadoxetic acid-enhanced MR imaging using CAIPIRINHA technique with CT angiography

PURPOSE

To retrospectively evaluate gadoxetic acid-enhanced magnetic resonance angiography (MRA) using controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique for mapping hepatic vascular anatomy in potential living liver donors, with CT angiography (CTA) as reference standard.

METHODS

82 potential living liver donors who underwent MRA and CTA were enrolled in this HIPAA-compliant IRB-approved study. MRA and CTA images were evaluated by two reviewers in consensus with respect to (1) image quality scores for depiction of the hepatic vessels and (2) accuracy of MRA for determining the hepatic vascular variants with CTA as reference standard. The image quality scores were compared using Fisher's exact test between MRA and CTA.

RESULTS

The accuracy for determining the hepatic arterial, portal, and hepatic venous variants and segment IV arterial origin was 73, 90, 79, and 55%, respectively, compared to CTA. However, subjective image quality for depiction of hepatic arteries in MRA was significantly lower than CTA (p < 0.001). The portal and hepatic venous image quality was almost equal in both modalities (p = 0.059) except left hepatic vein being depicted better on CT images (p = 0.023).

CONCLUSION

Gadoxetic acid-enhanced MRA using CAIPIRINHA technique is feasible for mapping hepatic vasculature in potential living liver donors, with moderate accuracy for arterial variants and good to excellent results for hepatic and portal vein variants, compared with CTA. However, the specific delineation of segment IV arterial origin was possible in just over half of the liver donors with MRA.

Evaluation of biliary ductal anatomy in potential living liver donors: comparison between MRCP and Gd-EOB-DTPA-enhanced MRI

PURPOSE

To compare magnetic resonance cholangiopancreatography (MRCP) and Gd-EOB-DTPA-enhanced MRI in the evaluation of the biliary anatomy in potential living liver donors (LLDs).

METHODS

A retrospective study was conducted in a tertiary care liver transplant center after obtaining ethics and institutional approvals. A total of 42 potential LLD MRI examinations were performed between November 2013 and March 2016. All patients underwent a standard MRI protocol which included MRCP and Gd-EOB-DTPA-enhanced MRI sequences in a single session. Three abdominal MR radiologists independently reviewed the studies and completed a customized data collection sheet for each MR sequence. The readers subjectively scored the bile duct visualization on each MR sequence on a Likert scale and classified the biliary anatomic configuration. Statistical analysis was performed using intraclass correlation coefficient and the McNemar Chi-square (χ ²) test.

RESULTS

The 42 potential LLDs included 22 males and 20 females with an age range of 18-60 years. There was 'good' or 'excellent' inter-reader agreement on either MRI examination for the visualization of the first- and second-order ducts and the majority of third-order ducts. 'Good' inter-reader agreement on Gd-EOB-DTPA-enhanced MRI and 'fair' inter-reader agreement on MRCP was noted for the left third-order medial duct. There was significantly better visualization of the cystic duct, left hepatic duct, and right second-order ducts on Gd-EOB-DTPA-enhanced MRI compared with MRCP. A 12.6% improvement in classifying the biliary branch pattern was also observed on Gd-EOB-DTPA-enhanced MRI compared with MRCP (P = 0.03).

CONCLUSION

Gd-EOB-DTPA-enhanced MRI provides additional diagnostic confidence over MRCP in the evaluation of the biliary ductal anatomy in potential LLDs.

Magnetic resonance cholangiopancreatography evaluation of intrahepatic bile duct variations with updated classification

PURPOSE

Preoperative detection of intrahepatic bile duct (IHBD) variations is essential to reduce surgical morbidity and mortality rates. Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive and reliable method for demonstrating the normal IHBD anatomy and its variations. This retrospective study aimed to identify and classify novel variations, except those already reported in the literature, using MRCP.

METHODS

MRCP examinations, which were conducted in two different centers in the last five years, were retrospectively evaluated. IHBD variations were recorded with respect to the Yoshida classification. In addition, newly detected variations that were not included in this classification were identified and classified.

RESULTS

MRCP examinations of 2624 patients were screened, and 2143 were determined to be eligible for evaluation. Of 2143 patients, 987 were males (average age, 54±18 years) and 1156 were females (mean age, 57±17 years). In this study, 10 novel variations that were not included in the Yoshida classification were identified in 14 patients.

CONCLUSION

MRCP is an effective, reliable, and noninvasive imaging method for evaluating the IHBD anatomy and its variations. Novel variations described in this study may help to better understand the biliary anatomy.

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.

Application of contrast-enhanced ultrasound after liver transplantation: Current status and perspectives

Liver transplantation is an effective treatment for patients with end-stage liver disease. Accurate imaging evaluation of the transplanted patient is critical for ensuring that the limited donor liver is functioning appropriately. Ultrasound contrast agents (UCAs), in combination with contrast-specific imaging techniques, are increasingly accepted in clinical use for the assessment of the hepatic vasculature, bile ducts and liver parenchyma in pre-, intra- and post-transplant patients. We describe UCAs, their technical requirements, the recommended clinical indications, image interpretation and the limitations for contrast-enhanced ultrasound applications in liver transplantation.

One-stop-shop preoperative evaluation for living liver donors with gadoxetic acid disodium-enhanced magnetic resonance imaging: efficiency and additional benefit

OBJECTIVE

To explore the efficiency, cost, and time for examination of one-stop-shop gadoxetic acid disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) in preoperative evaluation for parent donors by comparing with multidetector computer tomography combined with conventional MR cholangiopancreatography (MDCT-MRCP).

MATERIALS AND METHODS

Forty parent donors were evaluated with MDCT-MRCP, and the other 40 sex-, age-, and weight-matched donors with Gd-EOB-DTPA-enhanced MRI. Anatomical variations and graft volume determined by pre- and intra-operative findings, costs and time for imaging were recorded. Image quality was ranked on a 4-point scale and compared between both groups.

RESULTS

Gd-EOB-DTPA-enhanced MRI provided better image quality than MDCT-MRCP for the depiction of portal veins and bile ducts by both reviewers (p < 0.05), hepatic veins by one reviewer (p < 0.05), rather hepatic arteries by both reviewers (p < 0.01). Sixty-nine living donors proceeded to liver donation with all anatomical findings accurately confirmed by intra-operative findings. The "in-room" time of Gd-EOB-DTPA-enhanced MRI was 12 min longer than MDCT-MRCP. Gd-EOB-DTPA-enhanced MRI was cheaper than MDCT-MRCP (US$519.72 vs. US$631.85).

CONCLUSION

One-stop-shop Gd-EOB-DTPA-enhanced MRI has similar diagnostic accuracy as MDCT-MRCP and can provide additional benefit in terms of costs and convenience in preoperative evaluation for parent donors.

Combined parenchymal and vascular imaging: High spatiotemporal resolution arterial evaluation of hepatocellular carcinoma

PURPOSE

To assess the ability of high-resolution arterial phase imaging of hepatocellular carcinoma (HCC) to provide combined vascular characterization and parenchymal evaluation.

MATERIALS AND METHODS

Thirty-eight consecutive studies in cirrhotic patients with HCC scanned with a view-shared 2-point-Dixon-based Differential Subsampling with Cartesian Ordering (DISCO) sequence were analyzed. Lesion contrast relative to precontrast and adjacent parenchyma was evaluated and compared using a Fisher's exact test. Visibility of hepatic arteries and tumor feeding vessels were graded on a 5-point scale. Catheter angiography was used as a reference standard for arterial anatomy.

RESULTS

The high spatiotemporal multiphasic acquisition allowed imaging of both the angiographic and late arterial phase in 30 of 38 studies with good image quality. Maximal lesion enhancement compared to precontrast occurred more frequently during the late arterial phase compared to maximal lesion-to-adjacent, which occurred more frequently during the early arterial phase (P < 0.001). Common and proper hepatic arteries were visualized adequately in 100%, right hepatic artery in 94-97%, left hepatic artery in 94%, and segmental vessel in 83% of cases. Arterial variants were detected with sensitivity of 87-100% and specificity of 100%.

CONCLUSION

High spatiotemporal resolution arterial phase imaging provides multiple angiographic and arterial phases in a single breath-hold, enabling accurate depiction of vascular anatomy while maintain optimal arterial phase imaging for characterization of focal lesions.

Feasibility of liver graft procurement with donor gallbladder preservation in living donor liver transplantation

OBJECTIVE

Cholecystectomy is routinely performed at most transplant centers during living donor liver transplantation (LDLT). This study was performed to evaluate the feasibility of liver graft procurement with donor gallbladder preservation in LDLT.

METHODS

Eighty-nine LDLTs (from June 2006 to Dec 2012) were retrospectively analyzed at our hospital. The surgical approach for liver graft procurement with donor gallbladder preservation was assessed, and the anatomy of the cystic artery, the morphology and contractibility of the preserved gallbladder, postoperative symptoms, and vascular and biliary complications were compared among donors with or without gallbladder preservation.

RESULTS

Twenty-eight donors (15 right and 13 left-liver grafts) successfully underwent liver graft procurement with gallbladder preservation. Among the 15 right lobectomy donors, for 12 cases (80.0 %) the cystic artery originated from right hepatic artery. From the left hepatic artery and proper hepatic artery accounted for 6.7 % (1/15), respectively. Postoperative symptoms among these 28 donors were slight, although donors with cholecystectomy often complained of fatty food aversion, dyspepsia, and diarrhea during an average follow-up of 58.6 (44-78) months. The morphology and contractibility of the preserved gallbladders were comparable with normal status; the rate of contraction was 53.8 and 76.7 %, respectively, 30 and 60 min after ingestion of a fatty meal. Biliary and vascular complications among donors and recipients, irrespective of gallbladder preservation, were not significantly different.

CONCLUSIONS

These data suggest that for donors compliant with anatomical requirements, liver graft procurement with gallbladder preservation for the donor is feasible and safe. The preserved gallbladder was assessed as functioning well and postoperative symptoms as a result of cholecystectomy were significantly reduced during long-term follow-up.

Expectations from imaging for pre-transplant evaluation of living donor liver transplantation

Living donor liver transplant (LDLT) is a major surgical undertaking. Detailed pre-operative assessment of the vascular and biliary anatomy is crucial for safe and successful harvesting of the graft and transplantation. Computed tomography (CT) and magnetic resonance imaging (MRI) are currently the imaging modalities of choice in pre-operative evaluation. These cross-sectional imaging techniques can reveal the vascular and biliary anatomy, assess the hepatic parenchyma and perform volumetric analysis. Knowledge of the broad indications and contraindications to qualify as a recipient for LDLT is essential for the radiologist reporting scans in a pre-transplant patient. Similarly, awareness of the various anatomical variations and pathological states in the donor is essential for the radiologist to generate a meaningful report of his/her observations. CT and MRI have largely replaced invasive techniques such as catheter angiography, percutaneous cholangiography and endoscopic retrograde cholangiopancreatography. In order to generate a meaningful report based on these pre-operative imaging scans, it is also mandatory for the radiologist to be aware of the surgeon’s perspective. We intend to provide a brief overview of the common surgical concepts of LDLT and give a detailed description of the minimum that a radiologist is expected to seek and report in CT and MR scans performed for LDLT related evaluation.

Contrast-enhanced magnetic resonance angiography for the preoperative evaluation of hepatic vascular anatomy in living liver donors: a meta-analysis

RATIONALE AND OBJECTIVES

The objective of this study was to determine the diagnostic accuracy of contrast-enhanced magnetic resonance angiography (MRA) when used in the preoperative evaluation of hepatic vascular anatomy in living liver donors.

MATERIALS AND METHODS

A computer-assisted literature searching of EMBASE, PubMed (MEDLINE), and the Cochrane library databases was conducted to identify potentially relevant articles which primarily examined the utility of contrast-enhanced MRA in the preoperative evaluation of hepatic vascular anatomy in living liver donors. We used the Q statistic of chi-squared value test and inconsistency index (I-squared, I(2)) to estimate the heterogeneity of the data extracted from all selected studies. Meta-Disc software (version 1.4) (ftp://ftp.hrc.es/pub/programas/metadisc/Metadisc_update.htm) was used to perform our analysis.

RESULTS

Eight studies were included in the present meta-analysis. A total of 289 living liver donor candidates and 198 patients who underwent liver harvesting were included in the present study. The pooled sensitivities of hepatic artery (HA), portal vein (PV), and hepatic vein (HV) in this meta-analysis were 0.84, 0.97, and 0.94, respectively. The pooled specificities of HA, PV, and HV were 1.00, 1.00, and 1.00, respectively. The pooled diagnostic odds ratios of HA, PV, and HV were 127.28, 302.80, and 256.59, respectively. The area under the summary receiver-operating characteristic curves of HA, PV, and HV were 0.9917, 0.9960, and 0.9813, respectively.

CONCLUSIONS

The high sensitivity and specificity demonstrated in this meta-analysis suggest that contrast-enhanced MRA was a promising test for the preoperative evaluation of hepatic vascular anatomy in living liver donors.

Morphine three-dimensional T1 gadoxetate MR cholangiography of potential living related liver donors

PURPOSE

To assess low-dose morphine for distension and improved visualization of intrahepatic bile ducts on T1 MR cholangiography (MRC) in preoperative imaging of potential liver donors.

MATERIALS AND METHODS

Sixty-nine consecutive potential living related liver donors (mean age, 39 years; age range, 20 to 59 years) referred for pre-transplant MRI evaluation were evaluated without (n=30) or with (n=39) intravenous morphine injection (0.04 mg/kg). Morphine was injected pre-MRI while establishing intravenous access to allow ∼1 h for biliary distension before T1 MRC. Three radiologists reviewed intrahepatic biliary branch order visualization, common bile duct (CBD) diameter, and overall image quality. In 25 patients undergoing liver donation surgery, T1 MRC findings were correlated with intraoperative findings. This retrospective study was approved by the institutional review board.

RESULTS

Biliary visualization was improved post-morphine administration with biliary duct branch order visualization score of 3.2 and 3.3 at 45 and 60 min, respectively, compared with 2.7 without morphine (P<0.002); CBD diameter measured 5.3 and 5.5 versus 4.1 mm (P<0.005), and overall image quality score was 2.4 and 2.6 versus 1.8 (P<0.0006). Operative notes confirmed T1 MRC findings in 6/11 donors without morphine and 14/14 donors with morphine.

CONCLUSION

Intravenous low-dose morphine distends and improves visualization of bile ducts on T1 gadoxetate MRC.

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.

CT and MR cholangiography: advantages and pitfalls in perioperative evaluation of biliary tree

Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.

Relationship between the risk of bile duct injury during laparoscopic cholecystectomy and the types of preoperative magnetic resonance cholangiopancreatiocography (MRCP)

Backgrounds/Aims

Bile duct injury is one of the potential severe complications that can occur during laparoscopic cholecystectomy, which can be cause by anatomic variations in the confluence of the bile duct. Recently magnetic resonance cholangiopancreatiocography (MRCP) has become a helpful tool to detect bile duct variation on a preoperative basis and to prevent bile duct injury during laparoscopic cholecystectomy, as well other hepatic surgeries. This study aimed to clarify the types of bile duct on MRCP and to search for a method of avoiding injury during laparoscopic cholecystectomy.

Methods

Between January 2009 and December 2010, 277 patients underwent laparoscopic cholecystectomy with preoperative MRCP in our institution. On a retrospective basis, the bile ducts were categorized into 5 types according to the Couinaud classification system.

Results

The proportion of types was revealed type A (70.4%), type B (8.7%), type C (19.5%), type D (0.7%), type E (0%), and type F (0.7%), respectively. Bile duct injury occurred in 4 cases (1.4%) during laparoscopic cholecystectomy. In particular, the possibility of aberrant extrahepatic confluence (Type C and F) represented the highest risk of duct injury (OR=11.89 [CI: 1.21-116.53]).

Conclusions

Preoperative evaluation of the bile duct anatomy is important to avoid injury of duct during laparoscopic cholecystectomy. Specific types of bile duct variation should be considered as a high risk group for bile duct injury.

Magnetic resonance cholangiography in living donor liver transplantation

OBJECTIVE

Exact knowledge of biliary anatomy is essential in living donor liver transplantation. The purpose of this study was to evaluate the accuracy of pretransplant magnetic resonance cholangiography (MRC) in depicting the biliary anatomy in comparison with intraoperative cholangiography (IOC).

MATERIALS AND METHODS

From May 2006 to July 2009, 451 potential living liver donors underwent pretransplant evaluation at the Chang Gung Memorial Hospital-Kaohsiung Medical Center. Two hundred thirty-three donors underwent donor hepatectomy. Of these, only 203 donors with both preoperative MRC and IOC were included in this study.

RESULTS

Of the 451 potential donors, 218 (48.3%) were considered unsuitable for liver donation, hence was immediately disqualified after the initial evaluation for various reasons. Six of the 218 unsuitable donors (2.8%) were excluded due to complicated biliary anatomy. The overall accuracy rate of MRC for defining the biliary anatomy was 91.6%, with 84.9% sensitivity, 96% specificity, 88.2% positive predictive value, and 94.7% negative predictive value. There were 14 misidentified cases. The errors in MRC reading was largely attributed to the poor contrast between the biliary ducts and the surrounding tissues and organs. The concurrence between MRC and IOC were commendable (κ=0.9). No significant biliary complications were noted in the mismatch group.

CONCLUSION

MRC is essential for all pretransplantation evaluation with 91.6% accuracy rate.

Gadoxetic acid disodium-enhanced magnetic resonance imaging for biliary and vascular evaluations in preoperative living liver donors: comparison with gadobenate dimeglumine-enhanced MRI

PURPOSE

To compare gadoxetic acid disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine (Gd-BOPTA)-enhanced MRI in preoperative living liver donors for the evaluation of vascular and biliary variations.

MATERIALS AND METHODS

Sixty-two living liver donors who underwent preoperative MRI were included in this study. Thirty-one patients underwent MRI with Gd-EOB-DTPA enhancement, and the other 31 underwent MRI with Gd-BOPTA enhancement. Two abdominal radiologists retrospectively reviewed dynamic T1-weighted and T1-weighted MR cholangiography images and ranked overall image qualities for the depiction of the hepatic artery, portal vein, hepatic vein, and bile duct on a 5-point scale and determined the presence and types of normal variations in each dynamic phase. Semiquantitative analysis for bile duct visualization was also conducted by calculating bile duct-to-liver contrast ratios.

RESULTS

No statistical differences were found between the two contrast media in terms of hepatic artery or bile duct image quality by the two reviewers, or in terms of portal vein image quality by one reviewer (P > 0.05). Gd-BOPTA provided better image qualities than Gd-EOB-DTPA for the depiction of hepatic veins by both reviewers, and for the depiction of portal veins by one reviewer (P < 0.01). The two contrast media-enhanced images had similar bile duct-to-liver contrast ratios (P > 0.05). Regarding diagnostic accuracies with hepatic vascular/biliary branching types, no significant differences were observed between the two contrast media (P > 0.05).

CONCLUSION

Gd-EOB-DTPA could be as useful as Gd-BOPTA for the preoperative evaluation of living liver donors, and has the advantage of early hepatobiliary phase image acquisition.

MR imaging evaluation of the hepatic vasculature

Assessment of the hepatic vasculature is essential for tumor staging, surgical planning, and understanding of liver disease. Technological advances have made contrast-enhanced magnetic resonance (MR) imaging comparable to multidetector-row computed tomography for diagnostic vascular imaging with respect to spatial resolution. Unenhanced MR angiographic sequences enable reasonable clinical assessment of vessels without contrast agents in patients with contraindications or renal insufficiency. Furthermore, MR angiography may be used to provide directional information through manipulation of the signal intensity of flowing blood. A major limitation to consistent contrast-enhanced MR angiography is the timing of MR image acquisition with arrival of the contrast bolus in the structures of interest. In this article, the authors discuss currently available techniques for imaging of the hepatic vasculature.

Clinical applications of gadobenate dimeglumine-enhanced magnetic resonance cholangiography: an expanded pictorial review

Gadobenate dimeglumine (Gd-BOPTA) is taken up by functioning hepatocellular cells and is partially excreted into the biliary system; therefore, it can be used as a potential intrabiliary contrast agent for magnetic resonance cholangiography applications for various clinical conditions such as obstructive disorders (e.g., choledocholithiasis, hepatolithiasis), inflammatory disorders (e.g., acute cholecystitis, cholangitis), benign biliary disorders, and pre- and postprocedural evaluation of the biliary system. In this pictorial review, we aimed to demonstrate the clinical applications of Gd-BOPTA as an intrabiliary contrast agent for imaging various biliary pathologies.

Evaluating biliary anatomy and variations in living liver donors by a new technique: three-dimensional contrast-enhanced ultrasonic cholangiography

Accurate assessment of the biliary anatomy is important for the safety of liver donors in living donor liver transplantation (LDLT). We evaluated the biliary anatomy and variations of 12 living liver donors with 3-D contrast-enhanced ultrasonic cholangiography (3-D CEUSC) by injecting microbubble contrast agents into the common hepatic ducts intraoperatively. Two radiologists assessed the diagnostically adequate, delineation of biliary branch orders, visibility scores (grades 0 to 3) and anatomical patterns of the intrahepatic biliary tree by consensus. The results were compared with findings on intraoperative cholangiography (IOC) and surgery. 3-D CEUSC successfully demonstrated the spatial structure of the intrahepatic biliary tree in all 12 donors. The maximum branching order of intrahepatic bile ducts displayed on 3-D CEUSC was the fifth order in the right lobe and fourth order in the left lobe of the liver, respectively. The visibility scores of the first-order (3.00 +/- 0.00) and second-order (2.67 +/- 0.69) branches were significantly (p < 0.001) higher than that of the third-order (1.98 +/- 1.13) branches, whereas visibility scores of the second-order (2.88 +/- 0.34) and third-order (2.44 +/- 1.01) branches in the right lobe were significantly (p = 0.040 and p < 0.001, respectively) higher than those in the left lobe (2.46 +/- 0.88 and 1.33 +/- 0.99). The 3-D CEUSC images of the 12 donors were diagnostically adequate for evaluating the biliary anatomy. Normal biliary pattern in nine donors and biliary variations in three donors were confirmed by both IOC and surgical findings. 3-D CEUSC may be a potential alternative to IOC in the evaluation of biliary anatomical variation before graft harvesting in LDLT.

Intraoperative 'no go' donor hepatectomies in living donor liver transplantation

Donor safety is the paramount concern of living donor liver transplantation (LDLT). Although LDLT is employed worldwide, there is little data on rates and causes of 'no go' hepatectomies-patients brought to the operating room for possible donor hepatectomy whose procedure was aborted. We performed a single-center, retrospective review of all patients brought to the operating room for donor hepatectomy between October 2000 and November 2008. Of 257 right lobe donors, the donor operation was aborted in 12 cases (4.7%). The main reasons for stopping the operation were aberrant ductal or vascular anatomy (seven cases), unsuitable liver quality (three cases) or unexpected intraoperative events (two cases). Over the median period of follow-up of 23 months, there were no long-term complications of patients with aborted donor procedures. This report focuses exclusively on an important issue: the frequency and causes of no go decisions at a single large volume North American LDLT center. The rate of no go donor hepatectomies should be as low as possible without compromising donor safety--however, even with rigorous preoperative evaluation the rate of donor abortions will be significant. The default surgical position should always be to abort the donor operation if there is an unexpected finding that places the donor at increased risk.

Biliary tract depiction in living potential liver donors: intraindividual comparison of MR cholangiography at 3.0 and 1.5 T

PURPOSE

To intraindividually compare the accuracy of magnetic resonance (MR) cholangiography at 3.0 and 1.5 T for depicting biliary anatomy with intraoperative cholangiography as the reference standard and to compare the image quality for biliary tract visualization at these two field strengths.

MATERIALS AND METHODS

After obtaining institutional review board approval and informed consent, 52 living potential liver donors underwent MR cholangiography at both 1.5 and 3.0 T. The protocol included projectional single-section rapid acquisition with relaxation enhancement (RARE) and respiratory-triggered three-dimensional (3D) fast spin-echo (SE) T2-weighted sequences. Two readers independently analyzed images, scoring the visualization of all first- and second-order biliary branches on a four-point scale and determining the number of visible third-order branches.

RESULTS

MR cholangiography at 3.0 T correctly depicted biliary anatomy in 90.4% of subjects on combined analysis of both sequences by both readers, in 88.5% with projectional RARE images for both readers, and in 84.6% and 88.5% with 3D fast SE images for readers 1 and 2, respectively. MR cholangiography at 1.5 T showed 86.5% and 84.6% accuracy on combined analysis for readers 1 and 2, respectively; 78.8% and 75.0% accuracy on projectional RARE images for readers 1 and 2, respectively; and 84.6% and 86.5% accuracy with 3D fast SE images for readers 1 and 2, respectively. With the projectional RARE sequence, 3.0-T MR cholangiography demonstrated significantly higher mean visualization scores for second-order branches (reader 1: 2.29 vs 1.78, P = .01; reader 2: 2.52 vs 2.10, P < .01) and mean numbers of visible third-order branches (reader 1: 5.53 vs 4.21, P < .01; reader 2: 5.91 vs 3.74, P < .01) than did 1.5-T MR cholangiography.

CONCLUSION

Compared with 1.5-T MR cholangiography, 3.0-T MR cholangiography did not significantly increase accuracy for identification of biliary anatomy. Projectional RARE images at 3.0 T enabled better visualization of second- and third-order branches than did those at 1.5 T.

Morphine- and glucagon-augmented magnetic resonance cholangiopancreatography to evaluate living liver donors

The purpose of this study was to investigate the effectiveness of the combined use of intravenous morphine and intramuscular glucagon in improving magnetic resonance cholangiopancreatography (MRCP) image quality in donors for living-related liver transplantation. Sixteen healthy donor candidates underwent an MRCP study. Coronal, single-shot, fast spin-echo, heavily T2-weighted dynamic MRCP images were obtained before and 3 minutes after the intravenous administration of morphine HCl with a dose of 0.04 mg/kg. Thirty minutes after the injection of morphine, intramuscular glucagon was used. Another MRCP image of the same pulse sequence was generated 15 minutes after the injection of glucagon with a dose of 1 mg. The diameter, signal intensity, and number of branches of bile ducts in MRCP images taken immediately before and after the injection of morphine and after the injection of glucagon (plus delayed morphine effects) were compared and analyzed. In all 16 donor candidates, the diameters of the right and left hepatic ducts, common bile duct, and main pancreatic duct were significantly increased (P < 0.05) in the MRCP images taken 3 minutes after the injection of morphine and 15 minutes after the injection of glucagon (plus delayed morphine effects) in comparison with MRCP images taken before any drug administration. The qualitative grading scores of the signal intensity and order of branches of bile ducts revealed improvements in the MRCP images after the injection of glucagon (plus delayed morphine effects; P < 0.05). In conclusion, combining the intravenous administration of low-dose morphine and the intramuscular use of glucagon before MRCP examination improves the visualization of the nondilated biliary ductal anatomy, which is important for the preoperative biliary evaluation of donor candidates for living-related liver transplantation.

Imaging evaluation of the liver using multi-detector row computed tomography in micropigs as potential living liver donors

The shortage of organ donors has stimulated interest in the possibility of using animal organs for transplantation into humans. In addition, pigs are now considered to be the most likely source animals for human xenotransplantation because of their advantages over non-human primates. However, the appropriate standard values for estimations of the liver of micropigs have not been established. The determination of standard values for the micropig liver using multi-detector row computed tomography (MDCT) would help to select a suitable donor for an individual patient, determine the condition of the liver of the micropigs and help predict patient prognosis. Therefore, we determined the standard values for the livers of micropigs using MDCT. The liver parenchyma showed homogenous enhancement and had no space-occupying lesions. The total and right lobe volumes of the liver were 698.57 ± 47.81 ml and 420.14 ± 26.70 ml, which are 51.74% and 49.35% of the human liver volume, respectively. In micropigs, the percentage of liver volume to body weight was approximately 2.05%. The diameters of the common hepatic artery and proper hepatic artery were 6.24 ± 0.20 mm and 4.68 ± 0.13 mm, respectively. The hepatic vascular system of the micropigs was similar to that of humans, except for the variation in the length of the proper hepatic artery. In addition, the diameter of the portal vein was 11.27 ± 0.38 mm. In conclusion, imaging evaluation using the MDCT was a reliable method for liver evaluation and its vascular anatomy for xenotransplantation using micropigs.

Detection of biliary and vascular anatomy in living liver donors: value of gadobenate dimeglumine enhanced MR and MDCT angiography

OBJECTIVE

To evaluate the performance of magnetic resonance (MR) and multidetector computed tomography (MDCT) in the assessment of living donor's vascular and biliary anatomy, having surgical findings as reference standard.

METHODS

Thirty-two living liver donors underwent MR cholangiography (1.5-T; standard cholangiography pulse sequences and delayed acquisitions after administration of biliary contrast agent) for biliary anatomy evaluation. MDCT (16-row multidetector scanner, multiphase protocol, 3mm slice thickness) was also performed in all cases for the assessment of vascular anatomy before transplantation. Hepatic veins (<4mm in diameter) were not considered. MR and MDCT images interpretation was performed by two reviewers by consensus, based on source axial images, multiplanar reformats, and three-dimensional (3D) postprocessing images. Surgical intraoperative findings were used as standard of reference.

RESULTS

At surgery, 17 biliary anomalies, 3 portal anomalies, 32 venous and 8 arterial variants were found in the 32 patients. MR correctly identified 15/17 biliary anomalies, with a sensitivity of 88% and a specificity of 93%. MDCT correctly identified 8/8 arterial, 3/3 portal and 29/32 venous variants, with a sensitivity of 100% and 91%, respectively, and a specificity of 100%.

CONCLUSIONS

MR and MDCT proved to be efficient in evaluating living liver donor's biliary and vascular anatomy.

O papel da colangiografia por ressonância magnética na avaliação da anatomia biliar em doadores de transplante hepático intervivos

OBJETIVO: Avaliar a acurácia da colangiografia por ressonância magnética no estudo da anatomia biliar de doadores de fígado em correlação com achados operatórios. MATERIAIS E MÉTODOS: Estudo retrospectivo de 50 doadores submetidos a transplante hepático intervivos no Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR. As colangiografias foram analisadas e os resultados dos exames foram comparados com os achados intra-operatórios. Apenas alterações anatômicas que promoveram mudança de estratégia cirúrgica, não-evidenciadas previamente pela colangiografia por ressonância magnética, foram consideradas como discordantes. RESULTADOS: Foram encontradas variações pela colangiografia por ressonância magnética em 7 doadores e em 14 durante a cirurgia. Do total de pacientes, 41 resultados foram concordantes e 9 foram discordantes. A sensibilidade, a especificidade, o valor preditivo positivo, o valor preditivo negativo e a acurácia da colangiografia por ressonância magnética foram, respectivamente, de 43%, 97%, 86%, 81% e 81,6%. CONCLUSÃO: Conclui-se que a ressonância magnética é um método de imagem seguro e não-invasivo para avaliação pré-operatória das vias biliares de doadores e que algumas anomalias não são detectadas pela colangiografia por ressonância magnética.

High spatial resolution 3D MR cholangiography with high sampling efficiency technique (SPACE): comparison of 3T vs. 1.5T

PURPOSE

The aim of this study was to evaluate image quality of 3D MR cholangiography (MRC) using high sampling efficiency technique (SPACE) at 3T compared with 1.5T.

METHODS AND MATERIALS

An IRB approved prospective study was performed with 17 healthy volunteers using both 3 and 1.5T MR scanners. MRC images were obtained with free-breathing navigator-triggered 3D T2-weighted turbo spin-echo sequence with SPACE (TR, >2700ms; TE, 780ms at 3T and 801ms at 1.5T; echo-train length, 121; voxel size, 1.1mmx1.0mmx0.84mm). The common bile duct (CBD) to liver contrast-to-noise ratios (CNRs) were compared between 3 and 1.5T. A five-point scale was used to compare overall image quality and visualization of the third branches of bile duct (B2, B6, and B8). The depiction of cystic duct insertion and the highest order of bile duct visible were also compared. The results were compared using the Wilcoxon signed-ranks test.

RESULTS

CNR between the CBD and liver was significantly higher at 3T than 1.5T (p=0.0006). MRC at 3T showed a significantly higher overall image quality (p=0.0215) and clearer visualization of B2 (p=0.0183) and B6 (p=0.0106) than at 1.5T. In all analyses of duct visibility, 3T showed higher scores than 1.5T.

CONCLUSION

3T MRC using SPACE offered better image quality than 1.5T. SPACE technique facilitated high-resolution 3D MRC with excellent image quality at 3T.

Biliary tract depiction in living potential liver donors at 3.0-T magnetic resonance cholangiography

OBJECTIVES

To prospectively evaluate accuracy of biliary anatomy depiction and quality of biliary tract visualization of magnetic resonance cholangiography (MRC) at 3.0 T in living potential liver donors (LPLDs).

MATERIALS AND METHODS

Our institutional review board approved this study and did not require patient's informed consent. Thirty-three LPLDs underwent MRC at 3.0-T magnetic resonance and intraoperative cholangiography as the reference standard. MRC protocol included breath-hold rapid acquisition with relaxation enhancement (RARE) and respiratory-triggered 3-dimensional turbo spin-echo (TSE) T2-weighted sequence. Two readers independently analyzed 2 MRC image sets with a 2-week interval for delineating biliary anatomy and scoring degree of visualization of biliary branches with a 4-point scale, and recorded the number of visible third-order branches. One month later, both readers independently evaluated combined both MRC image set to assess biliary anatomy.

RESULTS

Biliary anatomy was correctly depicted by RARE sequence in 28 (84.8%) and 26 LPLDs (78.8%), by TSE sequence in 27 (81.8%) and 26 (78.8%), and by combined both sequences in 27 (81.8%) and 28 (84.8%), for readers 1 and 2, respectively. The mean second-order branch visualization scores for 2 readers were significantly higher for RARE images than for TSE (2.23 vs. 1.68, P = 0.02; 2.05 vs. 1.54, P = 0.02, respectively). The mean numbers of visible third-order branches were significantly higher for RARE images than TSE for both readers (4.36 vs. 3.04, P = 0.03; 4.72 vs. 3.32, P = 0.03, respectively).

CONCLUSIONS

In LPLDs, MRC at 3.0 T with both RARE and TSE sequences enables accurate depiction of biliary anatomy. RARE sequence more clearly visualizes second- and third-order biliary branches than TSE sequence.

MR cholangiopancreatography with T2-weighted prospective acquisition correction turbo spin-echo sequence of the biliary anatomy of potential living liver transplant donors

OBJECTIVE

The objective of our study was to evaluate the ability of a respiratory navigator-triggered T2-weighted turbo spin-echo (TSE) sequence with a prospective acquisition correction (PACE) technique for MR cholangiopancreatography (MRCP) to depict the biliary anatomy of living donor liver transplantation (LDLT) donors.

SUBJECTS AND METHODS

Forty potential LDLT donors who ranged in age from 19 to 54 years were prospectively evaluated with preoperative MRCP. MRCP was performed with a 1.5-T magnetic field using T2-weighted PACE TSE sequence. MRCP source data sets were processed with maximum-intensity-projection (MIP) and shaded surface display (SSD) algorithms. Findings were compared with intraoperative cholangiography. Biliary anatomy was classified according to the classification proposed by Huang and colleagues. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRCP for the detection of aberrant biliary anatomy were calculated.

RESULTS

Intraoperative cholangiography and biliary exploration revealed that 27 donor candidates (67.5%) had conventional and 13 (32.5%) had aberrant biliary anatomy. Two donors (5%) had type B biliary anatomy; eight donors (20%), type C; two donors (5%), type D; and one donor (2.5%), unclassified. The sensitivity of MRCP source data sets in differentiating aberrant biliary anatomies from nonaberrant ones was 100%, the specificity was 88.9%, and the accuracy was 92.5%. PPV and NPV were 81.3% and 100%, respectively. The sensitivity of MIP images in differentiating aberrant biliary anatomies was 100%, the specificity was 88.9%, and the accuracy was 92.5%. PPV and NPV were 81.3% and 100%, respectively. The sensitivity, specificity, accuracy, PPV, and NPV of the SSD images in detecting aberrant biliary anatomies were 100%, 77.8%, 85%, 68.4%, and 100%, respectively.

CONCLUSION

Preoperative MRCP using a respiratory navigator-triggered T2-weighted TSE sequence with a PACE technique accurately depicts the biliary anatomy in LDLT donors and may guide intraoperative management of the biliary tract.

The value of magnetic resonance cholangiography in the preoperative assessment of living liver donors

OBJECTIVE

The purpose of this study was to investigate the ability of magnetic resonance cholangiography (MRC) in the depiction of biliary anatomy of living liver donors by using intraoperative cholangiography (IOC) as a gold standard.

MATERIALS AND METHODS

Between 2004 and 2006, 86 potential adult-to-adult living donor liver transplantation donors had preoperative MRC at our institution. Of these, 24 potential donors were excluded due to various clinical factors. A total of 62 of these individuals were selected for liver donation and included in the study. MRC was performed on a 1.5-T scanner with breath-hold, rapid acquisition with relaxation enhancement (RARE) sequence with half-Fourier acquisition (HASTE; Siemens) and free-breathing, three-dimensional turbo spin-echo sequence with respiratory triggering. Thin- and thick-slab imaging techniques were employed with half-Fourier RARE MRC. IOC was performed in all 63 cases. The images of IOC and MRC were classified according to a modified Huang classification, independently. The results of the MRC were then compared with the IOC results.

RESULTS

IOC was used as the reference standard; a total of 43 (69.3%) liver donors were considered to have normal biliary anatomy, whereas 19 (30.7%) were considered to have variants of biliary anatomy. Compared with IOC, MRC correctly revealed biliary anatomy in 59 of 62 (95.1%) donors. The sensitivity, specificity, positive predictive value and negative predictive value of MRC in distinguishing normal and any type of variant biliary anatomy were 84.2%, 100%, 100%, and 93.4%, respectively.

CONCLUSION

MRC is an effective imaging technique for the preoperative evaluation of the biliary anatomy in living liver donors. However, MRC and IOC should be considered complementary to one another in order to avoid complications.

Preoperative volume prediction in adult living donor liver transplantation: how much can we rely on it?

Accurate preoperative prediction of functional donor and remnant hemiliver volumes in live donor liver transplantation is essential in preventing postoperative liver failure and optimizing safety. Our aim was (1) to evaluate volume variability associated with multiphasic CT imaging and (2) to determine over- or under-estimations of 3-D CT graft-volume assessments based on 'largest' versus 'smallest' CT phases with respect to intraoperative findings. Native, arterial and venous phase CT images from 83 potential live liver donors were subject to 3-D CT liver volume calculations and virtual 3-D liver partitioning. Estimates were compared to intraoperative volumes obtained in 43 cases. Calculated (preoperative) graft-volume-body-weight-ratios (GVBWR) versus measured (intraoperative) graft-weight-body-weight-ratios (GWBWR) were analyzed. Significant differences in total liver volume- and in graft-liver volume calculations were found among the largest (venous) and smallest (native) CT phases. High significant overestimations were observed in graft-volume determinations and in GVBWR-calculations based on the 'largest' CT phase when compared to intraoperatively obtained graft-weight and -GWBWR values. In contrast, differences among intraoperative measurements and preoperative calculations based on the 'smallest' CT phase yielded less significant overestimations. While 3-D CT volumetry based on the 'largest' (venous) CT phase is associated with considerable overestimation, 3-D volumetry based on the 'smallest' (native) CT phase accurately matches the intraoperative findings.

Assessment of future remnant liver regeneration after portal vein embolization using three-dimensional CT and MR volumetric analyses

The purpose of this study is to portray right portal vein embolization (PVE) as a valuable technique that helps in expanding the volume of the left liver lobe and discuss the relevant published work. We describe our experience with four patients who underwent PVE and analyse the value of CT and MRI in the preoperative evaluation of these patients. Four patients with hepatic malignancy (hepatocellular carcinoma) (n=2) and metastatic liver disease (n=2) underwent portal vein occlusion. PVE was carried out in three patients using polyvinyl alcohol and stainless steel coils. Portal vein ligation was carried out in the fourth patient. In patients who were candidates for right hepatectomy, CT volumetric analysis was carried out before the surgery to assess the total liver volume and the future remnant liver, which is the residual left hepatic volume (in cases of right hepatectomy) or left lateral segment volume (in cases of right tri-segmentectomy). Because the left lobe volumes were insufficient, patients were selected to undergo right PVE. Computed tomography volumetry was carried out 2-4 weeks after embolization to assess left hepatic lobe regeneration. Magnetic resonance volumetric analysis was carried out in two patients before and after embolization. All four patients had significant regeneration of the left lobe and tolerated the surgery with uneventful postoperative recovery.

Gadobenate dimeglumine-enhanced liver MRI as the sole preoperative imaging technique: a prospective study of living liver donors

OBJECTIVE

The objective of our study was to determine whether gadobenate dimeglumine-enhanced MRI is practical as the sole preoperative imaging technique for the examination of living liver donors.

SUBJECTS AND METHODS

Forty-four consecutive living donor candidates underwent liver MRI on a 1.5-T MR unit. The MR examination included in- and opposed-phase T1-weighted gradient-echo imaging, T2-weighted MR cholangiography, MR angiography (MRA) and parenchymal phase imaging after the administration of gadobenate dimeglumine, and 60-minute delayed T1-weighted MR cholangiography. Two abdominal radiologists analyzed the images regarding the depiction of the biliary duct anatomy and the hepatic vascular anatomy and for the presence of focal or diffuse liver disease. The findings were compared with intraoperative cholangiographic and surgical findings in 24 patients who underwent partial hepatectomy.

RESULTS

In the 24 patients who underwent liver harvesting, 10 had biliary anatomic variants confirmed by intraoperative cholangiography. T2-weighted MR cholangiography allowed a correct diagnosis in 75% (n = 18/24) and T1-weighted MR cholangiography in 79% (n = 19/24) of these patients. When we evaluated the bile duct anatomy using the combined findings of T2- and T1-weighted MR cholangiographic images, the diagnostic accuracy increased to 92% (n = 22/24), but the difference was not statistically significant (p > 0.05). MRA showed a diagnostic accuracy of 79% (n = 19/24) for the hepatic arterial anatomy, 100% (n = 24/24) for the portal venous anatomy, and 96% (n = 23/24) for the hepatic venous anatomy.

CONCLUSION

Gadobenate dimeglumine-enhanced MRI allows comprehensive assessment of the biliary and hepatic vascular systems and the hepatic parenchyma and can serve as the sole preoperative imaging test for living liver donor candidates.

Imaging of hepatic steatosis and fatty sparing

Radiology has gained importance in the non-invasive diagnosis of hepatic steatosis. Ultrasonography is usually the first imaging modality for the evaluation of hepatic steatosis. Unenhanced CT with or without dual kVp measurement and MRI with in and out of phase sequence can allow objective evaluation of hepatic steatosis. However, none of the imaging modalities can differentiate non-alcoholic steatohepatitis/fatty liver disease from simple steatosis. Evaluation of hepatic steatosis is important in donor evaluation before orthotopic liver transplantation and hepatic surgery. Recently, one-stop shop evaluation of potential liver donors has become possible by CT and MRI integrating vascular, parenchymal, volume and steatosis evaluation. Moreover hepatic steatosis (diffuse, multinodular, focal, subcortical, perilesional, intralesional, periportal and perivenular), hypersteatosis and sparing (geographic, nodular and perilesional or peritumoral) can cause diagnostic problems as a pseudotumor particularly in the evaluation of oncology patients. Liver MRI is used as a problem-solving tool in these patients. In this review, we discuss the current role of radiology in diagnosing, quantifying hepatic steatosis and solutions for diagnostic problems associated with fatty infiltration and sparing.

Preoperative evaluation of hepatic arterial and portal venous anatomy using the time resolved echo-shared MR angiographic technique in living liver donors

The purpose of this study was to determine whether MR angiography utilizing the time resolved echo-shared angiographic technique (TREAT) can provide an effective assessment of the hepatic artery (HA) and portal vein (PV) in living donor candidates. MR angiography (MRA)was performed in 27 patients (23 men and 4 women; mean age, 31 years) by using TREAT. Two blinded radiologists evaluated HA anatomy, origin of segment IV feeding artery and PV anatomy in consensus. Qualitative evaluations of MRA images were performed using the following criteria: (a) overall image quality, (b) presence of artifacts, and (c) degree of venous contamination of the arterial phase. Using intraoperative findings as a standard of reference, the accuracy for the HA anatomy, origin of segment IV feeding artery and PV anatomy on TREAT-MRA were 93% (25/27), 85% (23/27), and 96% (26/27), respectively. Overall image qualities were as follows: excellent (n=22, 81%), good (n=4, 15%), and fair (n=1, 4%). Significant artifacts or venous contamination of the arterial phase images was not noted in any patient. TREAT-MRA can provide a complete evaluation of HA and PV anatomy during preoperative evaluation of living liver donors. Furthermore, it provides a more detailed anatomy of the HA without venous contamination.

Preoperative volume calculation of the hepatic venous draining areas with multi-detector row CT in adult living donor liver transplantation: impact on surgical procedure

OBJECTIVE

The purpose was to assess the volumes of the different hepatic territories and especially the drainage of the right paramedian sector in adult living donor liver transplantation (ALDLT).

METHODS

CT was performed in 40 potential donors of whom 28 underwent partial living donation. Data sets of all potential donors were postprocessed using dedicated software for segmentation, volumetric analysis and visualization of liver territories. During an initial period, volumes and shapes of liver parts were calculated based on the individual portal venous perfusion areas. After partial hepatic congestion occurring in three grafts, drainage territories with special regard to MHV tributaries from the right paramedian sector, and the IRHV were calculated additionally. Results were visualized three-dimensionally and compared to the intraoperative findings.

RESULTS

Calculated graft volumes based on hepatic venous drainage and graft weights correlated significantly (r = 0.86, P < 0.001). Mean virtual graft volume was 930 ml and drained as follows: RHV: 680 ml, IRHV: 170 ml (n = 11); segment 5 MHV tributaries: 100 ml (n = 16); segment 8 MHV tributaries: 110 ml (n = 20). When present, the mean aberrant venous drainage fraction of the right liver lobe was 28%.

CONCLUSION

The evaluated protocol allowed a reliable calculation of the hepatic venous draining areas and led to a change in the hepatic venous reconstruction strategy at our institution.

Hepatic macrosteatosis: predicting appropriateness of liver donation by using MR imaging--correlation with histopathologic findings

PURPOSE

To retrospectively evaluate the diagnostic performance of magnetic resonance (MR) imaging in predicting the appropriateness of liver donation in potential living liver donors by using histopathologic results as the reference standard.

MATERIALS AND METHODS

This study was approved by institutional review board; all patients gave informed consent for the use of MR data for future research. Fifty-seven potential liver donors (40 male, 17 female; age range, 17-57 years; mean age, 32 years) underwent dual-echo 1.5-T MR imaging. Two radiologists qualitatively graded each MR image, with consensus for disagreements. Livers were assigned one of three degrees of hepatic steatosis on the basis of changes in hepatic signal intensity (SI) between in-phase and opposed-phase images. For quantitative analysis, a third radiologist calculated mean hepatic and mean splenic SI by averaging 25 hepatic regions of interest and three splenic regions of interest. Relative SI decrease (RSID) in the liver on opposed-phase images compared with in-phase images was calculated. Linear regression analysis was used to correlate RSID with the degree of total steatosis, macrosteatosis, and microsteatosis. Diagnostic performance for predicting the appropriateness of liver donation was analyzed.

RESULTS

Histologic findings of macrosteatosis resulted in 52 patients being categorized as appropriate donors, with the remaining five being categorized as inappropriate donors. RSID was correlated with total steatosis (r = 0.850). When the RSID criterion for inappropriateness of liver donation was set at 20%, the sensitivity, specificity, and accuracy were 100%, 92.3%, and 93%, respectively. When RSID was used, four livers that had been misclassified as inappropriate for transplantation were found to have microsteatosis of various degrees and a less than moderate degree of macrosteatosis at histologic analysis. Qualitative and quantitative analyses were comparably accurate.

CONCLUSION

When an RSID criterion of less than 20% was used, dual-echo MR imaging facilitated the correct prediction of appropriateness of liver donation in 53 of 57 patients.

Interventional radiology in liver transplantation

Improvements in surgical technique, advances in the field of immunosuppresion and the early diagnosis and treatment of complications related to liver transplantation have all led to prolonged survival after liver transplantation. In particular, advances in diagnostic and interventional radiology have allowed the Interventional Radiologist, as part of the transplant team, to intervene early in patients presenting with complications related to organ transplant with resultant increase in graft and patient survival. Such interventions are often achieved using minimally invasive percutaneous endovascular techniques. Herein we present an overview of some of these diagnostic and therapeutic approaches in the treatment and management of patients before and after liver transplantation.

Evaluation of Living Liver Donors with an All-inclusive 3D Multi–Detector Row CT Protocol

PURPOSE

To prospectively assess parenchymal, vascular, and biliary anatomy of potential living liver donors with an all-inclusive multi-detector row computed tomographic (CT) approach.

MATERIALS AND METHODS

A total of 250 potential living liver donors (112 women, 138 men; mean age, 37 years) underwent three-phase, dual-enhancement multi-detector row CT to delineate biliary, vascular, and parenchymal morphology according to an institutional review board-approved protocol. Informed consent was obtained from all subjects. For display of the biliary system, the first CT image set was collected after the infusion of a biliary contrast agent. CT angiography was subsequently performed, after automated injection of a conventional iodinated contrast agent, to display the arterial and portal-hepatic venous systems. All data sets were reconstructed in 1-mm sections. Data analysis was based on source images, multiplanar reconstructions, and three-dimensional postprocessing images; was performed in consensus by two radiologists; and was focused on the detection of biliary and vascular variants, exclusion of focal liver lesions, and determination of hepatic volumes. Preoperative findings were correlated with intraoperative findings (available in 62 subjects).

RESULTS

Technical failures were experienced in 10 of 250 examinations. Twenty-seven subjects had moderate adverse reactions related to the biliary contrast agent. Benign hepatic lesions were detected in 61 candidates; one candidate had a renal cell carcinoma. Underlying biliary and vascular anatomy was displayed at least to the second intrahepatic branch in all but seven patients. Detected anatomic variants involved the biliary (38.8%), arterial (40.0%), portal venous (21.4%), and hepatic venous (43.5%) systems. Correlation with intraoperative findings was excellent. Some biliary (n = 4), arterial (n = 5), portal venous (n = 1), and hepatic venous (n = 6) variants were missed or misinterpreted at initial reading of preoperative data; however, variants could be retrospectively depicted in all but one biliary case and one hepatic venous case.

CONCLUSION

The outlined three-phase, dual-enhancement multi-detector row CT protocol represents an all-inclusive approach to evaluate potential living liver donors in a single diagnostic step.

Preoperative evaluation of the hepatic vascular anatomy in living liver donors: Comparison of CT angiography and MR angiography

PURPOSE

To compare the diagnostic performance of CT angiography (CTA) and MR angiography (MRA) for preoperative hepatic vascular evaluation in living liver donors.

MATERIALS AND METHODS

Twenty-eight living donor candidates underwent preoperative CTA and MRA. Two blinded radiologists evaluated the anatomic types of the hepatic artery (HA) and portal vein (PV), and the number of aberrant hepatic veins (HVs) on both CTA and MRA, independently. Four grades of confidence levels were used to indicate the clarity of depiction of the HA and PV. Surgical findings were used as a standard of reference.

RESULTS

For determining the anatomic types of the HA and PV, and the number of aberrant HVs, CTA and MRA did not significantly differ in terms of accuracy ([89%, 96%, and 68% on CTA] vs. [86%, 93%, and 68% on MRA] for reader 1, P>0.05; and [93%, 100%, and 86% on CTA] vs. [89%, 93%, and 79% on MRA] for reader 2, P>0.05). Confidence for the depiction of major branches of HA and PV did not differ between CTA and MRA, except for a better depiction of the left HA (LHA) on CTA (P<0.05)

CONCLUSION

In living donor candidates, both CTA and MRA can provide a complete evaluation of the hepatic vascular anatomy.