Premalignant Lesions in the Kidney Transplant Candidate.

End-stage kidney disease patients who are referred for transplant undergo an extensive evaluation process to ensure their health prior to transplant due in part to the shortage of available organs. Although management and surveillance guidelines exist for malignancies identified in the transplant and waitlist populations, less is written about the management of premalignant lesions in this population. This review covers the less common premalignant lesions (intraductal papillary mucinous neoplasm, gastrointestinal stromal tumor, thymoma, and pancreatic neuroendocrine tumor) that can be found in the transplant candidate population. High-level evidence for the management of these rarer premalignant lesions in the transplant population is lacking, and this review extrapolates evidence from the general population and should not be a substitute for a multidisciplinary discussion with medical and surgical oncologists.

A novel method for in vitro culture and expansion of nonhuman primate B cells.

BACKGROUND: Given the role of B cells in sensitization and antibody-mediated rejection pathogenesis, the ability to identify, isolate, and study B cells in vitro is critical for understanding these processes and developing novel therapeutics. While in vivo nonhuman primate models have been used to this end, an in vitro nonhuman primate model of B cell activation and proliferation has not been developed. METHODS: CD20+ B cells and CD3+ T cells were isolated using magnetic bead separation from the peripheral blood of naive and skin allograft sensitized nonhuman primates. Allogeneic B and T cells were co-cultured in plates pre-coated with murine stromal cells engineered to express human CD40L and stimulated with cytokines. Cells and supernatants were harvested every 2 days for immune phenotyping and donor specific antibody quantification by flow cytometry. RESULTS: The optimized culture system consisted of MS40L cells co-cultured with B and allogenic T cells and stimulated with cytokines. This culture system resulted in increased memory cells and plasmablasts over time compared to other culture systems. Comparison of culture of naïve and sensitized nonhuman primate samples revealed faster B cell exhaustion and marginally increased plasmablast differentiation in sensitized culture. Donor-specific antibody production was not observed in either culture group. CONCLUSIONS: This study describes the first in vitro nonhuman primate model of B cell activation and proliferation using both naïve and allosensitized samples. This model provides an opportunity for exploration of B cell mechanisms and novel therapeutics and is a preliminary step in the development of an in vitro germinal center model.

Belatacept-Based Maintenance Immunosuppression Controls the Post-Transplant Humoral Immune Response in Highly Sensitized Nonhuman Primates.

Preexisting donor-specific antibodies (DSA) to MHC antigens increase the risk of antibody-mediated rejection (AMR) in sensitized transplant recipients and reduces graft survival. Pretransplant desensitization with costimulation blockade and proteasome inhibition has facilitated transplantation in our preclinical nonhuman primate (NHP) model. However, long-term graft survival is limited by rebound of DSA after transplantation. In this study, we performed kidney transplants between highly sensitized, maximally MHC-mismatched NHPs (n=14). At kidney transplantation, primates received T cell depletion with rhesus-specific anti-thymocyte globulin (rhATG; n=10) or monoclonal anti-CD4 and anti-CD8 antibodies (n=4). Maintenance immunosuppression consisted of belatacept and tacrolimus (n=5) or belatacept and rapamycin (n=9) with steroids. Rebound of DSA post-kidney transplantation was significantly reduced compared with maintenance immunosuppression with tacrolimus, mycophenolate, and steroids. Protocol lymph node biopsy specimens showed a decrease in germinal center activity, with low frequencies of T follicular helper cells and class-switched B cells after kidney transplantation. Combined belatacept and rapamycin was superior in controlling viral reactivation, enabling weaning of ganciclovir prophylaxis. Tacrolimus was associated with increased morbidity that included cytomegalovirus and parvovirus viremia and post-transplant lymphoproliferative disorder. All primates in the tacrolimus/belatacept group failed discontinuation of antiviral therapy. Overall, belatacept-based immunosuppression increased AMR-free graft survival by controlling post-transplant humoral responses in highly sensitized NHP recipients and should be further investigated in a human clinical trial.

C3 complement inhibition prevents antibody-mediated rejection and prolongs renal allograft survival in sensitized non-human primates.

Sensitized kidney transplant recipients experience high rates of antibody-mediated rejection due to the presence of donor-specific antibodies and immunologic memory. Here we show that transient peri-transplant treatment with the central complement component C3 inhibitor Cp40 significantly prolongs median allograft survival in a sensitized nonhuman primate model. Despite donor-specific antibody levels remaining high, fifty percent of Cp40-treated primates maintain normal kidney function beyond the last day of treatment. Interestingly, presence of antibodies of the IgM class associates with reduced median graft survival (8 vs. 40 days; p = 0.02). Cp40 does not alter lymphocyte depletion by rhesus-specific anti-thymocyte globulin, but inhibits lymphocyte activation and proliferation, resulting in reduced antibody-mediated injury and complement deposition. In summary, Cp40 prevents acute antibody-mediated rejection and prolongs graft survival in primates, and inhibits T and B cell activation and proliferation, suggesting an immunomodulatory effect beyond its direct impact on antibody-mediated injury.

Preoperative carfilzomib and lulizumab based desensitization prolongs graft survival in a sensitized non-human primate model.

Sensitized patients are difficult to transplant due to pre-formed anti-donor immunity. We have previously reported successful desensitization using carfilzomib and belatacept in a non-human primate (NHP) model. Here we evaluated selective blockade of the co-stimulatory signal (CD28-B7) with Lulizumab, which preserves the co-inhibitory signal (CTLA4-B7). Five maximally MHC-mismatched pairs of NHPs were sensitized to each other with two sequential skin transplants. Individuals from each pair were randomized to either desensitization with once-weekly Carfilzomib (27mg/m2 IV) and Lulizumab (12.5mg/kg SC) over four weeks, or no desensitization (Control). NHPs then underwent life-sustaining kidney transplantation from their previous skin donor. Rhesus-specific anti-thymocyte globulin was used as induction therapy and immunosuppression maintained with tacrolimus, mycophenolate, and methylprednisolone. Desensitized subjects demonstrated a significant reduction in donor-specific antibody, follicular helper T cells (CD4+PD-1+ICOS+), and proliferating B cells (CD20+Ki67+) in the lymph nodes. Interestingly, regulatory T cell (CD4+CD25+CD127lo) frequency was maintained after desensitization in addition to increased frequency of naïve CD4 T cells (CCR7+CD45RA+) and naïve B cells (IgD+CD27-CD20+) in circulation. This was associated with significant prolongation in graft survival (MST = 5.8 ± 4.0 vs. 64.8 ± 36.3; p<0.05) and lower antibody-mediated rejection scores compared to control animals. However, all desensitized animals eventually developed AMR and graft failure. Desensitization with CFZ and Lulizumab improves allograft survival in allosensitized NHPs, by transient control of the germinal center and shifting of the immune system to a more naive phenotype. This regimen may translate into clinical practice to improve outcomes of highly sensitized transplant patients.

B cells in transplant tolerance and rejection: friends or foes?

Our understanding of the role of B cells in organ transplantation remains incomplete and continues to grow. The majority of research has focused on the detrimental role of antibodies that drive the development of pathogenesis of the transplanted organ. However, it has been shown that not all donor-specific antibodies are harmful and in some circumstances can even promote tolerance through the mechanism of accommodation. Furthermore, B cells can have effects on transplanted organs through their interaction with T cells, namely antigen presentation, cytokine production, and costimulation. More recently, the role and importance of Bregs was introduced to the field of transplantation. Due to this functional and ontogenetic heterogeneity, targeting B cells in transplantation may bring undesired immunologic side effects including increased rejection. Therefore, the selective control of B cells that contribute to the humoral response against donor antigens will continue to be an important and challenging area of research and potentially lead to improved long-term transplant outcomes.

Pretransplant Desensitization with Costimulation Blockade and Proteasome Inhibitor Reduces DSA and Delays Antibody-Mediated Rejection in Highly Sensitized Nonhuman Primate Kidney Transplant Recipients.

BACKGROUND: Patients with broad HLA sensitization have poor access to donor organs, high mortality while waiting for kidney transplant, and inferior graft survival. Although desensitization strategies permit transplantation via lowering of donor-specific antibodies, the B cell-response axis from germinal center activation to plasma cell differentiation remains intact. METHODS: To investigate targeting the germinal center response and plasma cells as a desensitization strategy, we sensitized maximally MHC-mismatched rhesus pairs with two sequential skin transplants. We administered a proteasome inhibitor (carfilzomib) and costimulation blockade agent (belatacept) to six animals weekly for 1 month; four controls received no treatment. We analyzed blood, lymph node, bone marrow cells, and serum before desensitization, after desensitization, and after kidney transplantation. RESULTS: The group receiving carfilzomib and belatacept exhibited significantly reduced levels of donor-specific antibodies (P=0.05) and bone marrow plasma cells (P=0.02) compared with controls, with a trend toward reduced lymph node T follicular helper cells (P=0.06). Compared with controls, carfilzomib- and belatacept-treated animals had significantly prolonged graft survival (P=0.02), and renal biopsy at 1 month showed significantly reduced antibody-mediated rejection scores (P=0.02). However, four of five animals with long-term graft survival showed gradual rebound of donor-specific antibodies and antibody-mediated rejection. CONCLUSIONS: Desensitization using proteasome inhibition and costimulation blockade reduces bone marrow plasma cells, disorganizes germinal center responses, reduces donor-specific antibody levels, and prolongs allograft survival in highly sensitized nonhuman primates. Most animals experienced antibody-mediated rejection with humoral-response rebound, suggesting desensitization must be maintained after transplantation using ongoing suppression of the B cell response.

Once-daily prolonged-release tacrolimus versus twice-daily tacrolimus in liver transplantation.

OBJECTIVE: For patients who have received a kidney transplant, studies have shown that once-daily prolonged-release tacrolimus (TAC) has similar efficacy and safety to standard twice-daily dosing. The purpose of this study was to perform a meta-analysis to compare the effectiveness and safety of daily TAC (TAC qd) versus standard twice-daily TAC (TAC bid) administration in liver transplantation (LT). DESIGN: Meta-analysis. SETTING AND PARTICIPANTS: We systematically searched the PubMed/MEDLINE, Web of Science, and Cochrane Library databases for studies comparing outcomes of LT patients who received TAC qd versus TAC bid. OUTCOME MEASURES: Results were reported as odds ratios (ORs) with 95% CIs. RESULTS: Six studies, which included 5179 LT recipients (TAC qd = 951; TAC bid = 4228) were included in the analysis. The TAC qd group had a low 1-year graft loss rate (OR 0.70 [95% CI 0.54-0.91], P = 0.008) and lower rate of biopsy-proven acute rejection (BPAR) at 90 days (OR 0.46 [95% CI 0.24-0.89], P = 0.02) compared with the TAC bid group. There was no significant difference in 1-year mortality or the incidence of adverse events after LT between the 2 groups. CONCLUSIONS: Current evidence suggests that TAC qd is safe and effective for LT patients during the first year after transplantation. Longer-term follow-up studies are necessary to determine if TAC qd is safe and effective beyond the first year after LT.

The past, present, and future of costimulation blockade in organ transplantation.

PURPOSE OF REVIEW: Manipulating costimulatory signals has been shown to alter T cell responses and prolong graft survival in solid organ transplantation. Our understanding of and ability to target various costimulation pathways continues to evolve. RECENT FINDINGS: Since the approval of belatacept in kidney transplantation, many additional biologics have been developed targeting clinically relevant costimulation signaling axes including CD40-CD40L, inducible costimulator-inducible costimulator ligand (ICOS-ICOSL), and OX40-OX40L. Currently, the effects of costimulation blockade on posttransplant humoral responses, tolerance induction, and xenotransplantation are under active investigation. Here, we will discuss these pathways as well as preclinical and clinical outcomes of biologics targeting these pathways in organ transplantation. SUMMARY: Targeting costimultion is a promising approach for not only controlling T cell but also B cell responses. Consequently, costimulation blockade shows considerable potential for improving outcomes in antibody-mediated rejection and xenotransplantation.

Outcome of the use of paediatric donor livers in adult recipients: A single Chinese centre experience.

BACKGROUND: Paediatric liver allografts sometimes are allocated to adult recipients when there are no suitable paediatric recipients on the waiting list. However, debate exits regarding the reported outcomes of liver transplants using such small grafts. METHODS: Records from adult patients undergoing liver transplantation between February 2010 and January 2016 who received whole grafts from paediatric (≤ 13 years) donors or ideal deceased adult (18-35 years) donors were reviewed. Patient and graft survival, post-transplant liver function, and complications between the two groups were compared. RESULTS: The baseline characteristics were comparable, except that the paediatric donor allografts had smaller size. The 3-month, 1-year, and 3-year rates of patient survival were 91.3%, 85.2%, and 85.2% in the paediatric donor group and 93.4%, 88.9%, and 85.0% in the adult donor group (P = 0.947), respectively. One patient receiving a paediatric allograft developed small-for-size liver syndrome post-transplantation. There was no difference in primary non-function, early allograft dysfunction, biliary complications, vascular complications, or infection between the two groups. CONCLUSION: Our study indicates that using paediatric donor livers in well-selected adult recipients is a safe procedure, considering there was no suitable paediatric recipient. However, the risk of portal hyperperfusion should be considered in clinical cases such as size-mismatched transplants.

A Propensity-matched Survival Analysis: Do Simultaneous Liver-lung Transplant Recipients Need a Liver?

BACKGROUND: There is debate whether simultaneous lung-liver transplant (LLT) long-term outcomes warrant allocation of 2 organs to a single recipient. We hypothesized that LLT recipients would have improved posttransplant survival compared with matched single-organ lung recipients with an equivalent degree of liver dysfunction. METHODS: The Organ Procurement and Transplant Network/United Network for Organ Sharing STAR file was queried for adult candidates for LLT and isolated lung transplantation from 2006 to 2016. Waitlist mortality and transplant odds were calculated for all candidates. Donor and recipient demographic characteristics were compiled and compared. The LLT recipients were matched 1:2 with a nearest neighbor method to single-organ lung recipients. Kaplan-Meier methods with log-rank test compared long-term survival between groups. Univariate regression was used to calculate the association of LLT and mortality within 6 months of transplant. A proportional hazards model was used to calculate risk-adjusted mortality after 6 months posttransplantation. RESULTS: Thirty-eight LLT patients were matched to 75 single-organ lung recipients. After matching, no differences in baseline demographics or liver function were observed between cohorts. Length of stay was significantly longer in LLT recipients compared to isolated lung recipients (45.89 days vs 22.44 days, P < 0.001). There was no significant difference in survival probability between LLT and isolated lung transplant (1 y, 89.5% vs 86.7%; 5 y, 67.0% vs 64.6%; P = 0.20). CONCLUSIONS: After matching for patient characteristics and level of liver dysfunction, survival in simultaneous LLT was comparable to isolated lung transplantation. Although this population is unique, the clinical picture prompting liver transplant is not clear. National guidelines to better elucidate patient selection are needed.

Kidney Donor Profile Index Is a Reliable Alternative to Liver Donor Risk Index in Quantifying Graft Quality in Liver Transplantation.

BACKGROUND: The most established metric for estimating graft survival from donor characteristics in liver transplantation is the liver donor risk index (LDRI). The LDRI is calculated from donor and transplant-related variables, including cold ischemic time. Because cold ischemic time is unknown at the time of organ offer, LDRI is not available for organ acceptance decisions. In contrast, the kidney donor profile index (KDPI) is derived purely from donor variables known at the time of offer and thus calculated for every deceased donor in the United States. The similarity in donor factors included in LDRI and KDPI led us to hypothesize that KDPI would reliably approximate LDRI in estimating graft survival in liver transplantation. METHODS: The United Network of Organ Sharing registry was queried for adults who underwent deceased donor liver transplantation from 2002 to 2016. The cohort was divided into quintiles of KDPI and LDRI, and graft survival was calculated according to Kaplan Meier. Hazard ratios for LDRI and KDPI were estimated from Cox proportional hazards models, and Uno's concordance statistic was compared. RESULTS: In our analysis of 63 906 cases, KDPI closely approximated LDRI in estimating liver graft survival, with an equivalent concordance statistic of 0.56. CONCLUSIONS: We conclude that KDPI can serve as a reasonable alternative to LDRI in liver acceptance decisions.

Donor liver apoptosis is associated with early allograft dysfunction and decreased short-term graft survival after liver transplantation.

BACKGROUND: The clinical significance of apoptosis in assessing the quality of donor liver grafts remains unknown. AIMS: This study aimed to determine whether apoptosis in a donor liver is predictive of early allograft dysfunction (EAD) and graft survival after liver transplantation (LT). METHODS: Donor liver specimens were analyzed for apoptosis using TUNEL assays. The prognostic factors for EAD were identified through logistic regression analyses, and a nomogram was developed. RESULTS: The apoptosis index of donor livers in EAD patients was significantly higher than that of donors livers in non-EAD patients (median 5.3; interquartile range [IQR] 3.4 vs 3.5; 3.6, P < 0.001). Multivariate analyses identified the apoptosis index of the donor liver (HR = 6.927, P < 0.001) and five other characteristics as independent predictors of EAD. A nomogram built on these predictive variables showed good calibration and discriminatory abilities, with a c-index value of 0.847. The 30-day graft survival rates in the high apoptosis index (apoptosis index >4.4%) group were significantly lower than those in the low apoptosis index (apoptosis index ≤4.4%) group (84.4% vs 97.6%, P = 0.004). CONCLUSIONS: Donor liver apoptosis plays a significant role in predicting EAD after LT. Furthermore, a high apoptosis index in the donor liver was associated with inferior graft survival in the short-term.

Improved survival in simultaneous lung-liver recipients and candidates in the modern era of lung allocation.

BACKGROUND: Liver-lung transplantation (LLT) is a rare procedure performed for patients with end-stage liver and lung disease. The lung allocation score (LAS), introduced in 2005, guides lung allocation including those receiving LLT. However, the impact of the LAS on outcomes in LLT is currently unknown. MATERIALS AND METHODS: The OPTN/United Network for Organ Sharing STAR file was queried for LLT candidates and recipients from 1988 to 2016. Demographic characteristics before (historic) and after (modern) the LAS were compared. Survival was analyzed with the Kaplan-Meier method and log-rank test. RESULTS: In total, 167 candidates were listed for LLT, and 62 underwent LLT. The historic cohort had a higher FEV1% (48.22% versus 29.82%, P = 0.014), higher creatinine (1.22 versus 0.72, P < 0.001), and a higher percentage with pulmonary hypertension as the indication for transplantation (40% versus 0%, P = 0.003) compared with the modern cohort. LLT candidates in the historic cohort had a lower rate of transplant per 100 candidates (10.87 versus 33.33, P < 0.0001) and worse waitlist survival (1 y: 69.6% versus 80.9%, 3 y: 39.1% versus 66.8%, P = 0.004). Post-transplant survival was significantly lower in the historic cohort (1 y: 50.0% versus 82.7%, 5 y: 40.0% versus 69.0%, 10 y: 20.0% versus 55.5%, P = 0.0099). CONCLUSIONS: Most analyses of LLT have included patients before and after the introduction of the LAS. Our study shows that LLT candidates and recipients before the modern allocation system had distinct baseline characteristics and worse overall survival. Although many factors contributed to recent improved outcomes, these cohorts are significantly different and should be treated as such in future studies.

Improved contemporary outcomes of liver transplantation for pediatric hepatoblastoma and hepatocellular carcinoma.

PURPOSE: Improvement in outcomes of LT for pediatric HB and HCC has been reported in small series. We analyzed national outcomes and changes in donor, recipient, and perioperative factors over time that may contribute to survival differences. METHODS: The UNOS database was queried for patients age <21 years that underwent LT for a primary diagnosis of HB or HCC (1987-2017). Subjects were divided into historic (transplant before 2010) and contemporary (transplant after 2010) cohorts. Baseline characteristics were compiled and examined. Survival was estimated using the Kaplan-Meier method and compared using the log-rank test. RESULTS: In total, 599 children with HB received LT (320 historic vs 279 contemporary). Concurrently, 141 children with HCC received LT (92 historic vs 49 contemporary). For both tumors, waitlist time decreased (HB 56.2 days historic vs 33.2 days contemporary, P = 0.017; HCC 189.3 days historic vs 71.7 days contemporary, P = 0.012). In the historic cohorts, patients with HB had a 1-year and 5-year OS of 84.6% and 75.1%, respectively. Survival for HCC was 84.4% and 59.9%, respectively. Outcomes improved in the contemporary era to 89.1% and 82.6% for HB, and 94.7% and 80.8% for HCC, respectively (both log-rank test P < 0.0001). CONCLUSION: Outcomes of LT have improved significantly, with contemporary survival now equivalent between these tumors and exceeding 80% 5-year OS. Future studies are needed to explore whether offering LT in patients that are resectable is justifiable.

The early outcomes of candidates with portopulmonary hypertension after liver transplantation.

BACKGROUND: Portopulmonary hypertension (PPH) was once regarded as a contraindicaton to liver transplantation (LT). However, growing evidence has indicated that PPH patients undergoing LT may show similar outcomes compared to those without PPH, and researchers have recommended it not be an absolute contraindication. Given this controversy, we aimed to identify and review the current evidence on this topic and to provide a comparison of the outcomes after LT between candidates with PPH and those without. METHODS: We systematically searched the MEDLINE, EMBASE and Cochrane Library databases for all studies that compared the outcomes of PPH patients and those without PPH after LT. All studies reporting outcomes of PPH patients versus those without PPH (Control) were further considered for inclusion in this meta-analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to compare the pooled data between PPH and Control groups. RESULTS: Eleven retrospective trials and one prospective, randomized, controlled trial, involving 37,686 transplant recipients were included. The PPH patients had increased 1-year mortality with an OR of 1.59 (95% CI = 1.26-2.01, P = 0.0001) compared to the control group. There was no significant difference in graft loss and 30-day mortality after LT between the two groups. CONCLUSIONS: Patients with PPH who underwent LT had increased 1-year mortality compared to those without PPH, while graft loss and 30-day mortality were similar. Nevertheless, LT may be a reasonable therapeutic option for some patients with PPH, but further studies are needed to identify those select patients with PPH who would benefit most from LT.

Contemporary Strategies and Barriers to Transplantation Tolerance.

The purpose of this review is to discuss immunologic tolerance as it applies to solid organ transplantation and to identify barriers that hinder the achievement of this long-term goal. First, the definition of tolerance and an introduction of mechanisms by which tolerance exists or can be achieved will be discussed. Next, a review of contemporary attempts at achieving transplant tolerance will be described. Finally, a discussion of the humoral barriers to transplantation tolerance and potential ways to overcome these barriers will be presented.

The ileal FGF15/19 to hepatic FGFR4 axis regulates liver regeneration after partial hepatectomy in mice.

Fibroblast growth factor (FGF) has been considered to modulate liver regeneration (LR) after partial hepatectomy (PH) at the tissue level. Previous studies have demonstrated that FGF15 and FGF19 induce the activation of its receptor, FGF receptor 4 (FGFR4), which can promote hepatocellular carcinoma progression and regulate liver lipid metabolism. In this study, we aimed to explore the role of the ileal FGF15/19- hepatic FGFR4 axis in the LR after PH. Male C57BL/6 mice aged 8-12 weeks were partially hepatectomized and assessed for expression of ileal FGF15/19 to hepatic FGFR4 signaling. We used recombinant human FGF19 protein and a small interfering RNA (siRNA) of FGFR4 to regulate expression of the FGF15/19-FGFR4 axis in vitro and in vivo. The proliferation and cell cycle of hepatocytes, the expression levels of FGF15/19-FGFR4 downstream molecules, liver recovery, and lipid metabolism were assessed. We found that both ileal and serum FGF15 expression were upregulated and hepatic FGFR4 was activated after PH in mice. FGF15/19 promoted cell cycle progression, enhanced proliferation, and reduced hepatic lipid accumulation of hepatocytes both in vitro and in vivo. Furthermore, the proliferative effect and lipid regulatory properties of FGF15/19 were dependent on FGFR4 in hepatocytes. In addition, ileal FGF15/19-hepatic FGFR4 transduction during hepatocyte proliferation was regulated by extracellular regulated protein kinase (ERK) 1/2. In conclusion, the ileal FGF15/19 to hepatic FGFR4 axis is activated and promotes LR after PH in mice, supporting the potential of ileal FGF15/19 to hepatic FGFR4 axis-targeted therapy to enhance LR after PH.

Accuracy of MR Imaging and MR Spectroscopy for Detection and Quantification of Hepatic Steatosis in Living Liver Donors: A Meta-Analysis.

Purpose To determine the accuracy of magnetic resonance (MR) imaging for detection and quantification of hepatic steatosis (HS) in living liver donor candidates. Materials and Methods A systematic search of the literature was performed to find studies on the diagnostic and quantitative accuracy of MR imaging for assessment of HS in liver donors. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used, and patient selection, index text, reference standard, and study flow and timing were assessed to evaluate the quality of each included study. Pooled sensitivity, specificity, positive and negative likelihood ratios, hierarchical summary receiver operating characteristic (ROC) curves, and the area under the curve were estimated by using hierarchical summary ROC and bivariate random-effects models. Results Eight studies involving 934 subjects were eligible for the meta-analysis. For detection of HS with MR imaging and/or MR spectroscopy in living liver donors, the pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio, respectively, were 0.89 (95% confidence interval [CI]: 0.75, 0.95), 0.84 (95% CI: 0.76, 0.89), 5.53 (95% CI: 3.71, 8.25), and 0.14 (95% CI: 0.06, 0.31). The area under the curve was 0.92 (95% CI: 0.89, 0.94). For detection of substantial HS (>10% to >30% HS at liver pathologic examination, as defined in each study), these corresponding diagnostic estimates were 0.91 (95% CI: 0.82, 0.95), 0.89 (95% CI: 0.84, 0.93), 8.30 (95% CI: 5.47, 12.59), 0.10 (95% CI: 0.05, 0.21), and 0.96 (95% CI: 0.93, 0.97), respectively. Moderate heterogeneity was detected. No publication bias was detected (P = .12). Conclusion MR imaging and MR spectroscopy show high sensitivity and specificity for detection of HS, especially when HS is substantial, and may be useful for noninvasive evaluation of HS in living liver donors. © RSNA, 2016 Online supplemental material is available for this article.