Reduction of Visceral Adiposity as a Predictor for Resolution of Nonalcoholic Fatty Liver in Potential Living Liver Donors.

This study aimed to determine the factors associated with resolution of nonalcoholic fatty liver (NAFL) after lifestyle intervention in potential living liver donors as assessed by the gold standards in a longitudinal setting. This retrospective study included 115 potential living liver donors (mean age, 30.5 ± 7.5 years; 101 men) with NAFL who underwent paired liver biopsies and abdominal computed tomography (CT) examinations before and after lifestyle intervention between January 2011 and December 2018. Anthropometry, laboratory parameters, body composition, and hepatic steatosis (HS) were evaluated before and after lifestyle intervention. Anthropometry, laboratory parameters, body composition, and HS were significantly decreased after lifestyle intervention (all, P < 0.001). Relative changes in HS were weakly correlated with relative changes in the visceral fat area (VFA; r = 0.278; P = 0.003) and subcutaneous fat area (r = 0.382; P < 0.001), but not with body weight, body mass index, or skeletal muscle area. Patients with resolved NAFL after lifestyle intervention had significantly lower VFA at follow-up than those with persistent NAFL (mean ± standard deviation, 69.8 ± 39.1 versus 91.5 ± 41.4 cm2 ; P = 0.01). Multivariable logistic regression analysis demonstrated that the relative reduction of VFA (odds ratio per percent, 1.031; 95% confidence interval, 1.010-1.053; P = 0.004) was a significant independent factor associated with resolved NAFL after lifestyle intervention. In potential living liver donors with NAFL, the reduction of VFA is a significant factor associated with the resolution of NAFL after lifestyle intervention.

Liver Imaging Reporting and Data System Category on Magnetic Resonance Imaging Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation Within the Milan Criteria: A Multicenter Study.

BACKGROUND: This study was designed to investigate the association between Liver Imaging Reporting and Data System (LI-RADS) category and recurrence of hepatocellular carcinoma (HCC) after primary liver transplantation (LT) within the Milan criteria. METHODS: This multicenter, retrospective study included 140 recipients who underwent living donor LT (LDLT) for treatment-naïve HCC and pretransplant contrast-enhanced magnetic resonance imaging (MRI) between 2009 and 2013. LI-RADS categories were assigned using LI-RADS version 2018. Recurrence-free survival (RFS) and associated factors were evaluated using Cox proportional hazards regression analysis, Kaplan-Meier analysis, and log-rank test. Histological grading and microvascular invasion (MVI) were analyzed on the pathologic examinations of explanted livers. RESULTS: The overall 1-, 3-, 5-, and 7-year RFS rates were 95.6%, 92.6%, 90.2%, and 89.3%, respectively. In the multivariable analysis, independent predictors of recurrence included HCCs categorized as LR-M (hazard ratio [HR], 18.68; 95% confidence interval [CI], 5.79-60.23; P < 0.001) and the largest tumor size of ≥ 3 cm on MRI (HR, 4.18; 95% CI, 1.42-12.37; P = 0.010). The 5-year RFS rate was significantly lower in patients with HCCs categorized as LR-M than in those with HCCs categorized as LR-5 or 4 (LR-5/4) (36.9% vs. 95.8%, respectively; P < 0.001). HCCs categorized as LR-M exhibited significantly more MVI than HCCs categorized as LR-5/4 (57.1% vs. 17.5%, respectively; P = 0.002). CONCLUSIONS: Patients with HCCs categorized as LR-M using LI-RADS version 2018 may have a worse prognosis after primary LT within the Milan criteria than those with HCCs categorized as LR-5/4.

Visceral adiposity as a risk factor for lean non-alcoholic fatty liver disease in potential living liver donors.

BACKGROUND AND AIM: This study aimed to investigate the relationship between hepatic steatosis (HS) evaluated by biopsy and visceral adiposity assessed by computed tomography in lean living liver donor candidates and to determine the risk factors for lean non-alcoholic fatty liver disease (NAFLD). METHODS: This retrospective study included 250 lean (body mass index, < 23 kg/m2 ) potential living liver donors (mean age, 31.1 ± 8.6 years; 141 men) who had undergone liver biopsy and abdominal computed tomography between 2017 and 2018. Anthropometry, laboratory parameters, body composition, and the degree of HS were evaluated. Logistic regression was used to identify independent predictors of lean NAFLD. RESULTS: The visceral fat area (VFA) was significantly correlated with the degree of HS in men (r = 0.408; P < 0.001) and women (r = 0.360; P < 0.001). The subcutaneous fat area was significantly correlated with the degree of HS in men (r = 0.398; P < 0.001), but not in women. The skeletal muscle area did not correlate with the degree of HS in either men or women. In the multivariable logistic regression analysis, the VFA (odds ratio [OR], 1.028; 95% confidence interval [CI], 1.013-1.044; P < 0.001) and subcutaneous fat area (OR, 1.016; 95% CI, 1.004-1.028; P = 0.009) were independent risk factors for lean NAFLD in men, and the VFA (OR, 1.036; 95% CI, 1.013-1.059; P = 0.002) was an independent risk factor for lean NAFLD in women. CONCLUSIONS: The severity of non-alcoholic fatty liver was positively correlated with visceral fat accumulation in a lean Asian population. Visceral adiposity may be a risk factor for lean NAFLD in potential living liver donors.

Lifestyle Modification Leads to Spatially Variable Reduction in Hepatic Steatosis in Potential Living Liver Donors.

The spatial variability of hepatic fat reduction in potential living liver donors with hepatic steatosis (HS) who undergo lifestyle modification has not been investigated. Here, we aimed to examine the intrasegmental and intersegmental variability of changes in liver attenuation on computed tomography (CT) in potential living liver donors with HS after diet modification and exercise. A total of 87 living liver donor candidates (30.5 ± 7.0 years; 74 males) with biopsy-proven macrovesicular fat (MaF) ≥10% were included. All underwent diet modification and exercise to improve HS, baseline and follow-up unenhanced CT scans, and liver biopsies. Attenuation and its variability (mean and standard deviation, respectively, in Hounsfield units) in segmental, lobar, superficial, deep, and whole areas of the liver were measured across 32 different regions of interest on both baseline and follow-up CT. At baseline, the right lobe and superficial areas of liver showed significantly lower and more variable attenuation than left lobe and deep areas. Greater variability was noted in patients with more severe HS. Mean interval changes in liver attenuation and variability before and after diet modification and exercise were 13.7 (range, -10.6 to 46.2) and 4.7 (1.6-10.6), respectively. The mean interval change in liver attenuation was significantly higher in the right lobe than in the left (14.7 versus 12.7; P < 0.001), and in superficial areas than in deep areas (14.0 versus 13.4; P = 0.02). Greater variability and larger interval changes in liver attenuation were noted in those who responded (≥20% decrease in MaF) to diet modification and exercise than in those who did not. In conclusion, potential living liver donors with HS show significant intrasegmental and intersegmental variability in hepatic fat reduction on CT before and after diet modification and exercise.

Gadoxetic acid-enhanced MRI as a predictor of recurrence of HCC after liver transplantation.

OBJECTIVES: To investigate the value of preoperative gadoxetic acid-enhanced MRI for tumor staging and recurrence prediction of hepatocellular carcinoma (HCC) after primary liver transplantation (LT). METHODS: This multicenter retrospective study included 122 recipients who underwent living donor LT (LDLT) for untreated HCC and pre-transplant gadoxetic acid-enhanced MRI from January 2009 to December 2013. Disease-free survival (DFS) was evaluated. Milan criteria, tumor grade, and microvascular invasion (MVI) were analyzed on the pathological examination of the explanted liver. RESULTS: The 1-, 3-, 5-, and 7-year DFS rates were 93.3%, 90.7%, 88.9%, and 86.1%, respectively. In the multivariable analysis, independent predictors of HCC recurrence were "beyond the Milan criteria" (hazard ratio [HR], 3.54; 95% confidence interval [CI], 1.13-11.12; p = 0.030) and peritumoral hypointensity on hepatobiliary phase (HBP) (HR, 18.30; 95% CI, 4.33-77.34; p < 0.001). Pre-transplant MRI yielded a 90.2% accuracy to categorize the Milan criteria when compared with the explanted liver. Peritumoral hypointensity on HBP was significantly associated with a worse tumor grade (p = 0.010) and MVI (p < 0.001). The 5-year DFS rate in patients with "beyond the Milan criteria" but the absence of peritumoral hypointensity on HBP was not different from that in patients "within the Milan criteria" (92.2% vs. 92.9%, p = 0.438). CONCLUSIONS: Pre-transplant gadoxetic acid-enhanced MRI may assist in the HCC recurrence risk prediction. KEY POINTS: • Lesions beyond the Milan criteria and peritumoral hypointensity on hepatobiliary phase (HBP) were independent predictors of HCC recurrence. • Peritumoral hypointensity on HBP significantly associated with a worse tumor grade and microvascular invasion.

Diagnostic Performance for Hepatic Artery Occlusion After Liver Transplantation: Computed Tomography Angiography Versus Contrast-Enhanced Ultrasound.

The purpose of this study was to compare the diagnostic performance of computed tomography angiography (CTA) and contrast-enhanced ultrasound (CEUS) when used to diagnose significant hepatic artery occlusion (HAO) in patients that was suspected on Doppler ultrasound (US). Among 3465 adult liver transplantations (LTs) performed between January 2010 and February 2018, 329 recipients were suspected of having HAO by Doppler US. In these patients, 139 recipients who had undergone both CTA and CEUS as second-line studies were included. CTA and CEUS were retrospectively reviewed using the criteria for HAO used in previous studies (CTA, ≥50% stenosis at the anastomosis; CEUS, no HA enhancement or delayed and discontinuous enhancement). The diagnostic values of CTA and CEUS were compared using the McNemar test. CEUS showed statistically significant better accuracy and specificity than CTA in patients with Doppler US abnormality seen after LT (accuracy, 99.3% versus 89.2%, P < 0.001; specificity, 100% versus 83.1%, P < 0.001). CTA had 15 false-positive diagnoses, and CEUS had 1 false-negative diagnosis. In conclusion, CEUS showed higher specificity and positive predictive value than CTA for the diagnosis of HAO in selected patients with a Doppler US abnormality. However, even if there is no HAO diagnosed on CEUS, continuous monitoring and follow-up imaging are required when HAO is strongly suspected in the clinical setting and on CTA.

Clinical usefulness of gadoxetic acid-enhanced MRI for evaluating biliary anatomy in living donor liver transplantation.

OBJECTIVES: To determine the incremental value of hepatobiliary-phase-MRC (HBP-MRC) added to T2-magnetic resonance cholangiography (T2-MRC) for evaluating biliary anatomy in living donor liver transplantation (LDLT) and to correlate T2+HBP-MRC findings with surgical results. METHODS: A total of 276 donors who underwent T2 and gadoxetic acid-enhanced MRI before right hemihepatectomy for LDLT between January and December 2016 were retrospectively enrolled. Two reviewers evaluated biliary anatomy classification using T2-MRC in the first session and T2+HBP-MRC in the second session. The sensitivity, specificity, and confidence level (5-point scale) of T2-MRC and T2+HBP-MRC for variant biliary anatomy were evaluated. The agreement rates between MRC and operative cholangiography for each biliary anatomy classification and the underestimation rates for multiple bile duct openings (BDOs) for both MRC techniques were evaluated. RESULTS: Of the 276 donors, variant biliary anatomy was observed in 36.2% (100/276). T2+HBP-MRC showed a significantly higher sensitivity for diagnosing variant biliary anatomy than T2-MRC alone (99.0% [99/100] vs. 89.0% [89/100], p = 0.006), with better observer confidence level (4.9 ± 0.3 vs. 4.6 ± 0.7, p < 0.001) and inter-observer agreement (kappa, 0.902 vs. 0.730). Compared with T2-MRC alone, T2+HBP-MRC provided significantly higher agreement with operative cholangiography in biliary anatomy classification (98.6% [272/276] vs. 89.9% [248/276], p < 0.001), and significantly lower underestimation rate for multiple BDOs (5.8% [16/276] vs. 9.4% [26/276], p = 0.002). CONCLUSION: T2+HBP-MRC might be considered than T2-MRC alone, as a better depiction of biliary anatomic variations, correlated with surgical findings. KEY POINTS: •T2+HBP-MRC predicted variant biliary anatomy more accurately than T2-MRC alone. •T2+HBP-MRC might have clinical usefulness by reducing the underestimation rate of multiple bile duct openings, which requires more complicated biliary anastomoses.

CT of acute rejection after liver transplantation: a matched case-control study.

PURPOSE: This study was conducted in order to investigate computed tomography (CT) findings associated with acute cellular rejection (ACR) following liver transplantation (LT) and their relevance to clinical outcomes. MATERIALS AND METHODS: We analyzed 120 patients with newly diagnosed ACR following LT for various liver diseases and 119 controls matched for age, sex, type of liver graft, and date of CT exam following LT. Two radiologists analyzed the images for morphological characteristics of the graft, morphological change in the major draining vein, graft enhancement in the portal venous phase, graft attenuation on noncontrast CT, and periportal halo. Univariate analysis was used to determine the association between radiological findings and ACR. Clinical outcomes, including treatment response and graft survival, were compared between patients with and without associated radiological findings. RESULTS: Morphological characteristics of the graft (i.e., globular swelling), morphological change in the major draining vein (i.e., nonanastomotic luminal narrowing), and heterogeneous enhancement were significantly associated with ACR (all p < 0.001). On univariate analysis, the severity of morphological characteristics of the grafts (mild/severe: odds ratio [OR], 19.98/32.24) and morphological change in the major draining vein (without/with prestenotic dilatation: OR, 4.17/22.5) were significantly associated with the increased possibility of an ACR diagnosis. Clinical outcomes for treatment response and graft survival were not significantly different between patients with and without associated radiological findings. CONCLUSIONS: Globular swelling, nonanastomotic stenosis with or without prestenotic dilatation of the major draining vein, and heterogeneous enhancement of the graft on portal venous-phase CT were significantly associated with ACR. KEY POINTS: • Globular swelling of the graft, nonanastomotic narrowing in the major vein, and heterogeneous graft enhancement on CT were significantly associated with acute cellular rejection (ACR). • Associated CT findings were highly specific but not sensitive for differentiating ACRs from matched controls.

Low Graft Attenuation at Unenhanced CT: Association with 1-Month Mortality or Graft Failure after Liver Transplantation.

Purpose To investigate whether low graft attenuation at unenhanced computed tomography (CT) is associated with 1-month mortality or graft failure after liver transplant and determine its diagnostic performance. Materials and Methods Included were 663 recipients who underwent CT imaging within 7 days after liver transplant between December 2014 and August 2016. Initial poor function (IPF) was diagnosed by using a combination of laboratory values within 7 days after liver transplant and subdivided patients into primary and secondary IPF. At 1 month after the operation, mortality and graft failure or survival in recipients was categorized. Two radiologists who were blinded to clinical data retrospectively and independently evaluated graft attenuation on unenhanced CT images (high or isoattenuation, graft attenuation greater than or equal to that of spleen; low, graft attenuation less than that of spleen). The interobserver agreement was evaluated by using intraclass correlation coefficient and κ statics. Incidence of low graft attenuation between recipients with IPF and those with normal function was compared by using χ2 test. The relationship between graft attenuation and outcome in primary and secondary IPF was evaluated by using log-rank test. Results Of 663 recipients, 114 had IPF (80 primary; 34 secondary). After 1 month, 11 had graft failure or died, whereas 652 survived. Low graft attenuation was more common in patients with IPF than in normal-function patients (P < .001). In the primary group (those without identifiable cause), 15 patients had low graft attenuation, which led to mortality or graft failure within 1 month in seven of those patients. No recipient with high or isoattenuation had 1-month mortality or graft failure (P < .001). The secondary group (those with identifiable cause) showed no significant association between graft attenuation and 1-month mortality and graft failure (P = .181). Values of low graft attenuation for 1-month mortality and graft failure in primary IPF were positive predictive value, 46.7%; negative predictive value, 100%; sensitivity, 100%; specificity, 89.0%; and accuracy, 90.0%. There was excellent interobserver agreement in the assessment of graft attenuation (intraclass correlation coefficient, 0.957; κ = 1.00). Conclusion Low graft attenuation can be associated with 1-month mortality or graft failure in liver graft recipients with primary IPF. © RSNA, 2017.

Effect of irradiation-induced intercellular adhesion molecule-1 expression on natural killer cell-mediated cytotoxicity toward human cancer cells.

BACKGROUND AIMS: Irradiation enhances the adhesion between natural killer (NK) cells and target cells by up-regulating intercellular adhesion molecule-1 (ICAM-1) on target cells. Therefore, we investigated the effect of irradiation-induced ICAM-1 expression on human cancer cells on NK cell-mediated cytotoxicity. METHODS: Expression levels of ICAM-1 on the target cell surface before and after irradiation of six human cancer cell lines (HL60, SKBR-3, T47D, HCT-116, U937 and U251) were analyzed by flow cytometry. Ex vivo expansion of NK cells from human peripheral blood mononuclear cells was performed by co-culture with irradiated K562 cells. The related adhesion molecule lymphocyte function-associated antigen 1 (LFA-1) on NK cells was analyzed by flow cytometry. An enzyme-linked immunosorbent assay was used to detect interferon-γ (IFN-γ), and WST-8 assays were performed to check NK cell cytotoxicity. Finally, blocking assays were performed using monoclonal antibodies against ICAM-1 or LFA-1. RESULTS: LFA-1 expression increased on NK cells after expansion (P <0.001). The expression of ICAM-1 was significantly upregulated by irradiation after 24 h in various cell lines, including HL60 (P <0.001), SKBR-3 (P <0.001), T47D (P <0.001) and U937 (P <0.001), although the level of expression depended on the cell line. ICAM-1 expression was extremely low before and after irradiation in U251 cells. NK cell-mediated cytotoxicity increased after irradiation of HL60 (P <0.001), SKBR-3 (P <0.001), T47D (P = 0.003), and U937 (P = 0.004) cells, in which ICAM-1 expression was significantly increased after irradiation. IFN-γ production by NK cells in response to HL60 (P <0.001) and T47D (P = 0.011) cells significantly increased after irradiation. NK cell-mediated cytotoxicity against irradiated SKBR-3 (P <0.001) and irradiated T47D cells (P = 0.035) significantly decreased after blocking of ICAM-1. Blocking of LFA-1 on NK cells resulted in reduced cytotoxicity against irradiated HL60 (P <0.001) and irradiated SKBR-3 (P <0.001). CONCLUSIONS: Irradiation upregulates ICAM-1 expression on the surface of human cancer cells and enhances activated NK cell-mediated cytotoxicity. Therefore, irradiation combined with NK cell therapy may improve the antitumor effects of NK cells.

MRI in donor candidates for living donor liver transplant: Technical and practical considerations.

In living donor liver transplantation (LDLT), a thorough preoperative evaluation of the donor is imperative to minimize the risk of the donors and improve the outcome of the recipients. In order to select the best candidate, knowledge of the liver volume, degree of steatosis, and anatomic variations in the vascular and biliary system in potential donors is crucial. With recent technical advances, magnetic resonance imaging (MRI) is increasingly replacing the need for computed tomography (CT) examination in essential steps of donor evaluation. Along with the introduction of higher gradient strength, novel pulse sequences, and innovative contrast media, MRI has a potential to serve as an "all-in-one" imaging package. In this review, we provide an overview of clinical and radiologic considerations related to LDLT and highlight the basics and up-to-date knowledge of MRI techniques for a comprehensive donor evaluation. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:1453-1467.

Computed tomography findings in ABO-incompatible living donor liver transplantation recipients with biliary strictures.

OBJECTIVES: To evaluate CT findings of biliary strictures in ABO-incompatible living donor liver transplantation (LDLT) recipients, with emphasis on associated 1-month post-transplantation CT findings, and evaluate clinical outcomes. METHODS: Of 351 ABO-incompatible recipients, we retrospectively evaluated CT scans in 65 recipients with biliary stricture. The biliary strictures on CT scans were classified as type A (perihilar) and type B (diffuse). Precedent CT abnormality patterns and the presence of a periportal halo sign at 1-month post-transplantation were evaluated. For each patient, clinical outcomes were evaluated. RESULTS: Of 65 ABO-incompatible recipients with biliary strictures, 36.9% had type B strictures. Compared with biliary strictures at diagnosis, similar CT abnormality patterns were observed for 84.4% in type A and 86.4% in type B strictures at 1-month post-transplantation. Complex periportal halo signs on the 1-month post-transplantation CT were more frequently noted for type B than type A strictures (86.4% vs. 3.1%, P < 0.001). Progressive clinical outcomes were more frequently observed for type B than type A strictures (79.2% vs. 26.8%, P < 0.001), with a significantly shorter graft survival time (46.4 months vs. 90.8 months, P < 0.001). CONCLUSION: CT abnormality patterns and complex periportal halo signs on 1-month post-transplantation CT may be clinically useful for managing biliary strictures in ABO-incompatible LDLT recipients. Key Points • Of ABO-incompatible LDLT recipients, type B biliary stricture incidence was 6.8%. • Of type B strictures, 86.4% exhibited similar CT abnormality patterns at 1-month post-transplantation. • Complex periportal halo at 1 month was significantly associated with type B strictures. • Progressive clinical outcomes were more frequently observed in type B strictures.

Visibility of the graft hepatic artery using superb microvascular imaging in liver transplantation recipients: initial experience.

Background Hepatic artery (HA) obstruction is one of the most threatening complications following liver transplantation (LT); however, conventional color Doppler imaging (CDI) suffers from technical limitations regarding the visualization of fine vessels and low-velocity blood flow. Purpose To test the visibility of HA in postoperative evaluation of LT using a superb microvascular imaging (SMI). Material and Methods This retrospective study was approved by our institutional review board. Fifty-five consecutive patients (58 grafts; mean age = 56 years) who underwent LT with Doppler ultrasonography (US) on postoperative day 1 were included. We compared the subjective visibility of HA and objective measurements of HA caliber, visible HA length on CDI, monochrome SMI (mSMI), contrast-enhanced mSMI (CE-mSMI), and contrast harmonic imaging (CHI). Reproducibility of HA caliber measurements on SMI techniques were also evaluated by using intraclass correlation coefficients (ICCs). Results The subjective image quality for visibility of HA tended to be graded higher with mSMI than CDI, and with CE-mSMI than mSMI ( P < 0.001). The overall reproducibility of HA caliber measurements was good to excellent for both mSMI and CE-mSMI (ICC = 0.674-0.855). HA caliber measurements on mSMI and CE-mSMI strongly correlated with CHI ( R = 0.785, 0.798, P < 0.001), while mean HA length on mSMI was significantly longer than on CDI (1.88 ± 0.83 vs. 1.42 ± 1.01cm, P = 0.004), and even longer on CE-mSMI (vs. 3.28 ± 1.11 cm, P < 0.001). Conclusion The mSMI technique shows good reproducibility and correlates well with currently used methods for postoperative evaluation of HA in LT recipients. It is further improved by administration of an US contrast agent.

MR cholangiography in potential liver donors: quantitative and qualitative improvement with administration of an oral effervescent agent.

PURPOSE: To determine whether an oral effervescent agent improves magnetic resonance cholangiography (MRC) images, both qualitatively and quantitatively, in potential live liver donors. MATERIALS AND METHODS: This retrospective study was approved by the Institutional Review Board, and informed consent was waived. Seventy potential liver donors underwent 2D MRC before and after administration of an oral effervescent agent. One radiologist measured relative contrast ratio (rC) and relative signal intensity (rS) for right and left intrahepatic ducts (RHD and LHD), and common hepatic duct (CHD). After assessment of overall image quality, two other radiologists independently scored visualization of five ductal segments (RHD, LHD, CHD, cystic, and common bile duct) and assessed the preferred image set. In consensus, they assessed the biliary anatomy. The data were analyzed using a paired t-test, Wilcoxon's signed-rank test, and chi-square test. RESULTS: Both rC and rS of RHD and CHD were significantly higher on MRC images after administration of an oral effervescent agent than before (P < 0.03). The overall image quality grades and biliary visualization scores for all five duct segments were significantly higher on MRC images after administration of an oral effervescent agent than before (P < 0.0001). Between these images, both readers more often preferred MRC images with an effervescent agent rather than those without this agent (reader 1: 56/70, 80.0%; reader 2: 55/70, 78.6%; P = 0.0003). The readers correctly assessed second-order biliary tract anatomy in two more subjects on MRC after administration of an effervescent agent than before. CONCLUSION: Oral administration of an effervescent agent improves MRC images, both qualitatively and quantitatively, in live liver donors. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1656-1663.

Coronal 2D MR cholangiography overestimates the length of the right hepatic duct in liver transplantation donors.

PURPOSE: To compare the length of the right hepatic duct (RHD) measured on rotatory coronal 2D MR cholangiography (MRC), rotatory axial 2D MRC, and reconstructed 3D MRC. MATERIALS AND METHODS: Sixty-seven donors underwent coronal and axial 2D projection MRC and 3D MRC. RHD length was measured and categorized as ultrashort (≤1 mm), short (>1-14 mm), and long (>14 mm). The measured length, frequency of overestimation, and the degree of underestimation between two 2D MRC sets were compared to 3D MRC. RESULTS: The length of the RHD from 3D MRC, coronal 2D MRC, and axial 2D MRC showed significant difference (p < 0.05). RHD was frequently overestimated on the coronal than on axial 2D MRC (61.2 % vs. 9 %; p < .0001). On coronal 2D MRC, four (6 %) with short RHD and one (1.5 %) with ultrashort RHD were over-categorized as long RHD. On axial 2D MRC, overestimation was mostly <1 mm (83.3 %), none exceeding 3 mm or over-categorized. The degree of underestimation between the two projection planes was comparable. CONCLUSION: Coronal 2D MRC overestimates the RHD in liver donors. We suggest adding axial 2D MRC to conventional coronal 2D MRC in the preoperative workup protocol for living liver donors to avoid unexpected confrontation with multiple ductal openings when harvesting the graft. KEY POINTS: • In living liver donors, RHD length influences the number of ductal openings. • Coronal 2D MRC overestimates the RHD length than does axial 2D MRC. • Adding axial 2D MRC to coronal 2D MRC may prevent overestimating RHD length.

Measurement of liver volumes by portal vein flow by Doppler ultrasound in living donor liver transplantation.

BACKGROUND: The accurate estimation of liver volume and right/left ratio in donor candidates is critical, but there is no method using portal vein (PV) flow. METHODS: Of 125 donor candidates, right/left liver volume ratio was estimated using ultrasound (US)-PV area ratio and Doppler US-PV flow ratio, and the results were compared with CT volumetry. We analyzed these results in 76 donors who underwent hemihepatectomy. We evaluated diagnostic values of Doppler US-PV flow for <30% remnant liver volume high-risk donors, and compared liver volume by Doppler US-PV flow with actual graft weight. RESULTS: In 125 donor candidates, 96.8% showed <10% difference between liver volume ratio by Doppler US-PV flow ratio and CT volumetry. Compared with CT volumetry, the mean percentage difference of liver volume ratio by Doppler US-PV flow ratio was significantly smaller than that by US-PV area ratio (±0.7% vs ±6.3%, P<.001). In 76 donors who underwent hemihepatctomy, results were similar, showing smaller mean percentage difference of liver volume ratio by Doppler US-PV flow ratio than that by US-PV area ratio (±1.0% vs ±6.0%, P<.001). Sensitivity and specificity for <30% remnant liver volume donors were 76.9% and 76.8%. Blood-free liver volume by Doppler US-PV flow was linearly correlated with graft weight (R2 =0.770, P<.001), although significantly different, with 8.5% error ratio (669.3±173.2 vs 633.7±187.1, P=.001). CONCLUSION: Doppler US-PV flow can effectively estimate right/left liver volume ratio in initial donor investigation. However, Doppler US-PV flow is not accurate in assessing donors with <30% remnant liver volume and in estimating actual graft weight.

N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein after portosystemic collateral embolization in liver transplantation recipient: what is the clinical significance?

Background An N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein was frequently observed after an intraoperative embolization of portosystemic collaterals performed to prevent portal steal in liver transplant (LT) recipients. The radiological and clinical features of NBCA emboli have not yet been described. Purpose To describe radiological and clinical features of NBCA embolus in graft portal vein after portosystemic collateral embolization in LT recipients. Material and Methods A total of 165 consecutive LT recipients who had undergone intraoperative NBCA embolization of varix were found in single institution's computerized databases of a clinical cohort of LT. Patients were evaluated for NBCA emboli (categorized into major and minor emboli according to location) on first postoperative computed tomography (CT). All electronic medical records and radiologic studies including follow-up was evaluated to determine any radiological and clinical abnormality associated with NBCA embolus. Results NBCA emboli were found in 24% (39/165) of recipients. Although most patients had minor emboli (77%, 30/39) without remarkable ultrasonography (US) abnormalities, seven (78%) of nine recipients with major emboli showed intraluminal echogenic lesions in graft portal vein on grayscale US, and five of them (71%) showed partial portal flow obstruction, although none exhibited any abnormality on contrast-enhanced US. Recipients with NBCA portal emboli showed no significant clinical abnormalities and were discharged safely. NBCA embolus eventually disappeared mostly within six months (82%, 32/39). Conclusion NBCA emboli are frequently observed after portosystemic collateral embolization in LT recipients and are not associated with poor clinical outcome. They may mimic ordinary thromboemboli on US.

CT Features of Primary Graft Nonfunction after Liver Transplantation.

Purpose To determine computed tomographic (CT) features of primary graft nonfunction (PNF) after liver transplantation in comparison with those of early graft failure or death by identifiable causes. Materials and Methods Institutional review board approval was obtained and informed consent was waived. Among 3947 adult liver transplantations performed in one institution between May 2002 and May 2015, 72 patients died or had graft failure within 10 days, and 38 of them were evaluated with CT. PNF was diagnosed in 21 patients. The other 17 patients who died or had early graft failure were considered the non-PNF control group. On unenhanced CT images, graft attenuation was compared qualitatively. Graft attenuation was measured quantitatively and, if available, the difference between preoperative and postoperative CT (interval change) attenuation was evaluated. Unenhanced CT was evaluated for relative parenchymal enhancement. Statistical analyses included the Fisher exact and χ2 tests with Yates correction and the Student t test. Results On unenhanced CT images, grafts with PNF more commonly showed low (eight of 26 [31%]) or extremely low (18 of 26 [69%]) qualitative attenuation compared with grafts in the non-PNF group (three of 21 [14%], one of 21 [5%]; P < .001). The mean attenuation value (30.5 HU ± 10.8) was significantly lower and the mean interval change (24.7 HU ± 12.5) was significantly higher in the PNF group than in the non-PNF group (49.7 HU ± 8.0 and 9.7 HU ± 10.1, respectively; P < .001 and P = .001). There was no significant difference in the proportion of grafts that showed poor enhancement on postcontrast CT images between the PNF group and the non-PNF group (nine of 24 [38%] vs two of 20 [10%], respectively; P = .08). Conclusion Recipients with PNF after liver transplantation tended to show low or extremely low attenuation on unenhanced CT images, and this finding was seen more frequently in patients with PNF than in those who died of identifiable causes and in those with early graft failure. © RSNA, 2016 Online supplemental material is available for this article.

Hepatic Angiomyolipoma Versus Hepatocellular Carcinoma in the Noncirrhotic Liver on Gadoxetic Acid-Enhanced MRI: A Diagnostic Challenge.

OBJECTIVE: The purpose of this study is to describe the imaging characteristics of hepatic angiomyolipoma (AML) on gadoxetic acid-enhanced MRI and to identify imaging features that are helpful for differentiating it from hepatocellular carcinoma (HCC) in a noncirrhotic liver. MATERIALS AND METHODS: We retrospectively identified 18 patients with pathologically proven hepatic AMLs who had undergone gadoxetic acid-enhanced MRI between 2008 and 2012. We randomly chose 36 patients with noncirrhotic liver who had a single HCC diagnosed radiologically during the same period. None of the HCCs was of the fibrolamellar variant. Two readers reviewed images in consensus to assess the lesion size, the presence of fat, signal intensity characteristics, enhancement profile, early draining veins, intratumoral vessels, and tumor capsules. The tumor-to-liver contrast ratios were measured. These features and the measurements were compared between the two groups. RESULTS: AMLs are more commonly found in women (83.3%), whereas HCCs are more common in men (75%) (p < 0.01). The size of AMLs (3.4 cm) and HCCs (4.3 cm) did not differ significantly. Intratumoral fat was identified in both AMLs (50.0%) and HCCs (30.6%). The dynamic enhancement profile (arterial hypervascularity and hypointensity during the delayed phase) was similar qualitatively and quantitatively except for the portal phase. AMLs and HCCs differed significantly with regard to isointensity on DWI (16.7% vs 0.0%; p = 0.03), washout in the portal phase (61.1% vs 88.9%; p = 0.03), early draining veins (27.8% vs 2.8%; p = 0.01), intratumoral vessels (55.6% vs 22.2%; p = 0.03), and presence of capsule (11.1% vs 50.0%; p = 0.01). CONCLUSION: On gadoxetic acid-enhanced MRI of noncirrhotic liver, AML is often indistinguishable from HCC on the basis of the enhancement profiles. Female sex and some imaging features including DWI could facilitate the differentiation.