Ehman, Richard L.

Abstract Background and Aims Although magnetic resonance elastography (MRE) has been well‐established for detecting and staging liver fibrosis, its prognostic role in determining outcomes of chronic liver disease (CLD) is mostly unknown. Approach and Results This retrospective study consisted of 1269 subjects who underwent MRE between 2007 and 2009 and followed up until death or last known clinical encounter or end of study period. Charts were reviewed for cirrhosis development, decompensation, and transplant or death. The cohort was split into baseline noncirrhosis (group 1), compensated cirrhosis (group 2), and decompensated cirrhosis (group 3). Cox‐regression analysis with age, sex, splenomegaly, CLD etiology, Child‐Pugh Score (CPS), Fibrosis‐4 Index (FIB‐4) score, and Model for End‐Stage Liver Disease (MELD)–adjusted HR for every 1‐kPa increase in liver stiffness measurement (LSM) were used to assess the predictive performance of MRE on outcomes. Group 1 ( n = 821) had baseline median LSM of 2.8 kPa, and cirrhosis developed in 72 (8.8%) subjects with an overall rate of about 1% cirrhosis/year. Baseline LSM predicted the future cirrhosis with multivariable adjusted HR of 2.38 ( p < 0.0001) (concordance, 0.84). In group 2 ( n = 277) with baseline median LSM of 5.7 kPa, 83 (30%) subjects developed decompensation. Baseline LSM predicted the future decompensation in cirrhosis with FIB‐4 and MELD‐adjusted HR of 1.22 ( p < 0.0001) (concordance, 0.75). In group 3 ( n = 171) with median baseline LSM of 6.8 kPa (5.2, 8.4), 113 (66%) subjects had either death or transplant. Baseline LSM predicted the future transplant or death with HR of 1.11 ( p = 0.013) (concordance 0.53) but not in CPS and MELD‐adjusted models ( p = 0.08). Conclusion MRE‐based LSM is independently predictive of development of future cirrhosis and decompensation, and has predictive value in future transplant/death in patients with CLD.

Abstract Background Magnetic resonance imaging (MRI) and MRI‐based elastography (MRE) are the most promising noninvasive techniques in assessing liver diseases. The purpose of this study was to evaluate an advanced multiparametric imaging method for staging disease and assessing treatment response in realistic preclinical alcohol‐associated liver disease (ALD). Methods We utilized four different preclinical mouse models in our study: Model 1—mice were fed a fast‐food diet and fructose water for 48 weeks to induce nonalcoholic fatty liver disease; Model 2—mice were fed chronic‐binge ethanol (EtOH) for 10 days or 8 weeks to induce liver steatosis/inflammation. Two groups of mice were treated with interleukin‐22 at different time points to induce disease regression; Model 3—mice were administered CCl 4 for 2 to 4 weeks to establish liver fibrosis followed by 2 or 4 weeks of recovery; and Model 4—mice were administered EtOH plus CCl 4 for 12 weeks. Mouse liver imaging biomarkers including proton density fat fraction (PDFF), liver stiffness (LS), loss modulus (LM), and damping ratio (DR) were assessed. Liver and serum samples were obtained for histologic and biochemical analyses. Ordinal logistic regression and generalized linear regression analyses were used to model the severity of steatosis, inflammation, and fibrosis, and to assess the regression of these conditions. Results Multiparametric models with combinations of biomarkers (LS, LM, DR, and PDFF) used noninvasively to predict the histologic severity and regression of steatosis, inflammation, and fibrosis were highly accurate (area under the curve > 0.84 for all). A three‐parameter model that incorporates LS, DR, and ALT predicted histologic fibrosis progression ( r = 0.84, p < 0.0001) and regression ( r = 0.79, p < 0.0001) as measured by collagen content in livers. Conclusion This preclinical study provides evidence that multiparametric MRI/MRE can be used noninvasively to assess disease severity and monitor treatment response in ALD.

MRE is a noninvasive novel MRI modality that detects changes in tissue viscoelastic properties by imaging shear wave propagation. Renal artery stenosis (RAS) induces kidney fibrosis, yet we have previously shown that concomitant reductions in renal perfusion pressure mask an increase in cortical stiffness. We hypothesized that due to its lower vascular volume and turgor, change es in medullary elasticity in RAS would be detectable by MRE. MRE 3D elastograms were obtained in pigs after 10 weeks of RAS or matched controls (n=6 per group), and contrast‐enhanced computed tomography images obtained in the same pigs guided selection of MRE medullary regions of interest (Fig 1). Trichrome staining was used for computer‐aided quantification of medullary fibrosis ex‐vivo. The renal medulla was significantly more fibrotic (5.96±0.19 vs. 1.82±0.49%, p<0.001) and stiffer (10.9±0.84 vs. 7.88±0.26 kPa, p<0.05) in RAS compared to controls (Fig 1 and 2). The histological degree of medullary fibrosis directly correlated with MRE‐derived stiffness (R 2 =0.55, p<0.05, Fig 3). This study therefore suggests that renal medullary MRE may be useful for detection of chronic kidney fibrosis in RAS. Grant Funding Source: NIH DK73608, HL77131 , HL085307 , and EB001981

Abstract Purpose:Quantify in vivo biomechanical tissue properties in various breast densities and in normal risk and high risk women using Magnetic Resonance Imaging (MRI)/MRE and examine the association between breast biomechanical properties and cancer risk.Methods: Patients with normal risk or high risk of breast cancer underent 3.0 T breast MR imaging and elastography. Breast parenchymal enhancement (BPE), density (from most recent mammogram), stiffness, elasticity, and viscosity were recorded. Within each breast density group (non-dense versus dense), stiffness, elasticity, and viscosity were compared across risk groups (normal versus high). A multivariable logistic regression model was used to evaluate whether the MRE parameters (separately for stiffness, elasticity, and viscosity) predicted risk status after controlling for clinical factors.Results: 50 normal risk and 86 high risk patients were included. Risk groups were similar on age, density, and menopausal status. Among patients with dense breasts, mean stiffness, elasticity, and viscosity were significantly higher in high risk patients (N = 55) compared to normal risk patients (N = 34; all p < 0.001). Stiffness remained a significant predictor of risk status (OR=4.26, 95% CI [1.96, 9.25]) even after controlling for breast density, BPE, age, and menopausal status. Similar results were seen for elasticity and viscosity.Conclusion: A structurally-based, quantitative biomarker of tissue stiffness obtained from MRE is associated with differences in breast cancer risk in dense breasts. Tissue stiffness could provide a novel prognostic marker to help identify high risk women with dense breasts who would benefit from increased surveillance and/or risk reduction measures.

PurposeTo address the need for a method to acquire 3D data for MR elastography (MRE) of the whole brain with substantially improved spatial resolution, high SNR, and reduced acquisition time compared with conventional methods.MethodsWe combined a novel 3D spiral staircase data‐acquisition method with a spoiled gradient‐echo pulse sequence and MRE motion‐encoding gradients (MEGs). The spiral‐out acquisition permitted use of longer‐duration motion‐encoding gradients (ie, over two full oscillatory cycles) to enhance displacement SNR, while still maintaining a reasonably short TE for good phase‐SNR. Through‐plane parallel imaging with low noise penalties was implemented to accelerate acquisition along the slice direction. Shared anatomical information was exploited in the deblurring procedure to further boost SNR for stiffness inversion.ResultsIn vivo and phantom experiments demonstrated the feasibility of the proposed method in producing brain MRE results comparable to the spin‐echo–based approaches, both qualitatively and quantitatively. High‐resolution (2‐mm isotropic) brain MRE data were acquired in 5 minutes using our method with good SNR. Joint deblurring with shared anatomical information produced SNR‐enhanced images, leading to upward stiffness estimation.ConclusionA novel 3D gradient‐echo–based approach has been designed and implemented, and shown to have promising potential for fast and high‐resolution in vivo MRE of the whole brain.

10541 Background: Biomechanical tissue properties may vary in the breasts of patients at elevated risk for breast cancer. We aim to quantify in vivo biomechanical tissue properties in various breast densities and in both normal risk and high risk women using Magnetic Resonance Imaging (MRI)/MRE and examine the association of biomechanical properties of the breast with cancer risk. Methods: In this IRB–approved prospective single-institution study, we recruited two groups of women differing by breast cancer risk to undergo a 3.0 T dynamic contrast enhanced MRI/MRE of the breast. Low-average risk women were defined as having no personal or significant family history of breast cancer, no prior high risk breast biopsies and a negative mammography within 12 months. High-risk breast cancer patients were recruited from those patients who underwent standard of care breast MR. Within each breast density group (non-dense versus dense), two-sample t-tests were used to compare breast stiffness, elasticity, and viscosity across risk groups (low-average vs high). Results: There were 50 low-average risk and 86 high-risk patients recruited to the study. The risk groups were similar on age (mean age = 55.6 and 53.6 years), density (68% vs. 64% dense breasts) and menopausal status (66.0% vs. 69.8%). Among patients with dense breasts, mean stiffness, elasticity, and viscosity were significantly higher in high risk patients ( N = 55) compared to low-average risk patients ( N = 34; all p < 0.001). In the multivariate logistic regression model, breast stiffness remained a significant predictor of risk status (OR=4.26, 95% CI [1.96, 9.25]) even after controlling for breast density, MRI BPE, age, and menopausal status. Similar results were seen for breast elasticity (OR=4.88, 95% CI [2.08, 11.43]) and viscosity (OR=11.49, 95% CI [1.15, 114.89]). Conclusions: Structurally-based, quantitative biomarker of tissue stiffness obtained from global 3D breast MRE is associated with differences in breast cancer risk in dense breasts. As such, tissue stiffness could provide a novel prognostic marker to help identify the subset of high-risk women with dense breasts who would benefit from increased surveillance.[Table: see text]

Abstract Background MR elastography can determine organ‐related stiffness, which reflects the degree of fibrosis. Liver stiffness increases in cirrhosis, and stiffness increases further post‐prandially due to increased portal blood in‐flow. Non‐selective beta‐blockers (NSBB) reduce the portal venous inflow, but their effect on liver and spleen stiffness are disputed. Aims To assess whether MR elastography of the liver or spleen reflects the severity of cirrhosis, whether treatment with NSBB changes liver and spleen stiffness and whether changes in stiffness can predict the effect of NSBB on portal pressure. Methods Fifty‐two patients with cirrhosis underwent liver vein catheterization and two‐dimensional (2D) MR elastography on separate days. Thirty‐six of the patients had a hepatic venous pressure gradient (HVPG) of ≥12 mmHg and were tested prior to, and after, intravenous infusion of NSBB using HVPG measurement and MR elastography. Results HVPG showed a strong, positive, linear relationship with liver stiffness ( r 2 = 0.92; P < .001) and spleen stiffness ( r 2 = 0.94; P < .001). The cut‐off points for identifying patients with a HVPG ≥ 12 mmHg were 7.7 kPa for liver stiffness (sensitivity 0.78, specificity 0.64) and 10.5 kPa for spleen stiffness (sensitivity 0.8, specificity 0.79). Intravenous administration of NSBB significantly decreased spleen stiffness by 6.9% (CI: 3.5‐10.4, P < .001), but NSBB had no consistent effect on liver stiffness. However, changes in spleen stiffness were not related to the HVPG response ( P = .75). Conclusions Two‐dimensional MR elastographic estimation of liver or spleen stiffness reflects the degree of portal hypertension in patients with liver cirrhosis, but changes in stiffness after NSBB do not predict the effect on HVPG.

Abstract Background Liver disease remains a significant cause of morbidity and mortality in HIV-infected persons. Soluble CD163 is a marker of Kupffer cell activation that is highly associated with development of hepatic fibrosis. The relative contributions of HIV-associated systemic immune activation vs other etiologies of injury are poorly characterized. Methods We utilized subjects in the Miami Adult Studies on HIV (MASH) cohort to evaluate 464 participants including 361 people with HIV (PWH) and 103 hepatitis C virus (HCV)/HIV-uninfected controls. Subjects underwent testing for hepatic fibrosis using both magnetic resonance elastography and the Enhanced Liver Fibrosis Index. Steatosis was evaluated by magnetic resonance imaging–derived proton density fat fraction. Immune activation markers and cytokines were quantitated using Luminex methodologies. Results Participants with HIV with or without HCV coinfection had higher levels of sCD163 than uninfected controls (P &lt; .05). Soluble sCD163 was highly associated with elevated alanine aminotransferase, a key marker of inflammation/injury and with hepatic fibrosis. Hepatic steatosis was also associated with a cytokine pattern suggestive of Kupffer cell activation but was not associated with an increase in sCD14 or sCD27. Conclusions Injury and resultant hepatic fibrosis occur by distinct though overlapping mechanistic pathways. In PWH, sCD163 is highly associated with both injury and fibrosis, suggesting that persistent systemic immune activation is a major contributor to long-term outcomes, adding to damage caused by alcohol, steatosis, and other hepatotoxic drug effects.

In persons living with HIV (PLWH), there are multiple sources of liver injury. Gene polymorphisms of PNPLA3 (patatin-like phospholipase domain-containing protein 3) have been identified as an important cofactor for increased disease severity in both alcoholic and non-alcoholic steatohepatitis (NASH). We utilized a well-characterized cohort of ethnically and racially diverse patients with HIV to define the prevalence of PNPLA3 SNPs (single nucleotide polymorphism) (rs738409), and to determine the relationship to hepatic steatosis and liver fibrosis. Steatosis was determined using MRI-PDFF (magnetic resonance imaging-determined proton density fat fraction) and fibrosis was estimated using MR Elastography (MRE). From the Miami Area HIV Study (MASH) cohort, 100 HIV positive participants and 40 controls (HCV/HIV = 20; HCV and HIV negative = 20) were evaluated. Nearly 40% of all participants carried the variant G allele associated with increased liver disease severity and 5% were homozygotic GG. The variant SNP occurred most frequently in those self-identified as Hispanic compared to white or Black participants. Hepatic steatosis (>5% fat) was present significantly more often in those without HIV vs. those with (p < 0.001). Putative NAFLD/NASH was found to be present in 6% of tested subjects, who were HIV monoinfected. BMI was lower in those that carried the G allele for PNPLA3. This finding suggests that PNPLA3 may be an independent component to NAFLD (non-alcoholic fatty liver disease)/NASH development and longitudinal follow-up of the cohort is warranted.