The Combination of MR Elastography and Proton Density Fat Fraction Improves Diagnosis of Nonalcoholic Steatohepatitis.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide. It is subdivided into nonalcoholic fatty liver (NAFL) and the more aggressive form, nonalcoholic steatohepatitis (NASH), which carries a higher risk of developing fibrosis and cirrhosis. There is currently no reliable non-invasive method for differentiating NASH from NAFL. PURPOSE: To investigate the ability of magnetic resonance imaging (MRI)-based imaging biomarkers to diagnose NASH and moderate fibrosis as well as assess their repeatability. STUDY TYPE: Prospective. SUBJECTS: Sixty-eight participants (41% women) with biopsy-proven NAFLD (53 NASH and 15 NAFL). Thirty participants underwent a second MRI in order to assess repeatability. FIELD STRENGTH/SEQUENCE: 3.0 T; MR elastography (MRE) (a spin-echo echo-planar imaging [SE-EPI] sequence with motion-encoding gradients), MR proton density fat fraction (PDFF) and R2* mapping (a multi-echo three-dimensional gradient-echo sequence), T1 mapping (a single-point saturation-recovery technique), and diffusion-weighted imaging (SE-EPI sequence). ASSESSMENT: Quantitative MRI measurements were obtained and assessed alone and in combination with biochemical markers (cytokeratin-18 [CK18] M30, alanine transaminase [ALT], and aspartate transaminase [AST]) using logistic regression models. Models that could differentiate between NASH and NAFL and between moderate to advanced fibrosis (F2-4) and no or mild fibrosis (F0-1), based on the histopathological results, were identified. STATISTICAL TESTS: Independent samples t-test, Pearson's chi-squared test, area under the receiver operating characteristic curve (AUROC), Spearman's correlation, intra-individual coefficient of variation, and intraclass correlation coefficient (ICC). Statistical significance was set at P < 0.05. RESULTS: There was a significant difference between the NASH and NAFL groups with liver stiffness assessed with MRE, CK18 M30, and ALT, with an AUROC of 0.74, 0.76, and 0.70, respectively. Both MRE and PDFF contributed significantly to a bivariate model for diagnosing NASH (AUROC = 0.84). MRE could significantly differentiate between F2-4 and F0-1 (AUROC = 0.74). A model combining MRE with AST improved the diagnosis of F2-4 (AUROC = 0.83). The ICC for repeatability was 0.94 and 0.99 for MRE and PDFF, respectively. DATA CONCLUSION: MRE can potentially diagnose NASH and differentiate between fibrosis stages. Combining MRE with PDFF improves the diagnosis of NASH. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Consensus-Based Technical Recommendations for Clinical Translation of Renal Phase Contrast MRI.

BACKGROUND: Phase-contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC-MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC-MRI as a clinically useful tool. PURPOSE: To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC-MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies. STUDY TYPE: Systematic consensus process using a modified Delphi method. POPULATION: Not applicable. SEQUENCE FIELD/STRENGTH: Renal fast gradient echo-based 2D PC-MRI. ASSESSMENT: An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4-10) years of experience in 2D PC-MRI formulated consensus statements on renal 2D PC-MRI in two rounds of surveys. Starting from a recently published systematic review article, literature-based and data-driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated. STATISTICAL TESTS: Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60-74% agreement among the experts. RESULTS: Among 60 statements, 57 (95%) achieved consensus after the second-round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC-MRI data acquisition, processing, and reporting. DATA CONCLUSION: These recommendations might promote a widespread adoption of renal PC-MRI, and may help foster the set-up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC-MRI. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1.

Long-term effects of dapagliflozin plus saxagliptin versus glimepiride on a background of metformin in patients with type 2 diabetes: Results of a 104-week extension to a 52-week randomized, phase 3 study and liver fat MRI substudy.

AIM: To report the results of a 104-week extension to a 52-week study in which dapagliflozin plus saxagliptin (DAPA+SAXA) improved glycaemic control, liver fat and metabolic variables compared with glimepiride (GLIM) in participants with type 2 diabetes (T2D) receiving background metformin. MATERIALS AND METHODS: This extension to a 52-week global, multicentre, parallel-group, active-controlled, double-blind study (NCT02419612) continued randomized participants (1:1) on DAPA+SAXA (10/5 mg) plus placebo, or GLIM (1-6 mg) plus placebo, once daily. Eligible participants were aged ≥18 years, had T2D (glycated haemoglobin [HbA1c] 58.5-91.3 mmol/mol [7.5%-10.5%]), and a body mass index of 20.0 to 45.0 kg/m2 , and were receiving metformin (MET; ≥1500 mg/d). Key outcomes were: requirement for treatment intensification, based on HbA1c ≥53 mmol/mol (7%); achieving therapeutic glycaemic response; and changes in adipose tissue and liver fat on magnetic resonance imaging in a substudy. RESULTS: Overall, 382 participants entered and 338 completed the 104-week extension period (MRI substudy, n = 82). The need for treatment intensification during the 156-week period was lower for DAPA+SAXA+MET (37.0%) than GLIM+MET (55.6%; hazard ratio 0.52, 95% confidence interval [CI] 0.39-0.68; P < 0.001). At week 156, 21.4% of DAPA+SAXA+MET versus 11.7% of GLIM+MET participants achieved therapeutic glycaemic response (HbA1c <53 mmol/mol; odds ratio 2.1, 95% CI 1.23-3.42; P = 0.006). DAPA+SAXA+MET led to greater adjusted mean reductions from baseline in liver fat and visceral and subcutaneous adipose tissue volumes versus GLIM+MET at week 122 (least-squares mean difference from GLIM+MET -4.89%, -0.41 L and -0.44 L, respectively; nominal P values ≤ 0.008). Safety was consistent with that of the monocomponents. CONCLUSIONS: Overall, glycaemic control, metabolic benefits and efficacy were better maintained with DAPA+SAXA+MET than with GLIM+MET in T2D.

Dapagliflozin plus saxagliptin add-on to metformin reduces liver fat and adipose tissue volume in patients with type 2 diabetes.

AIM: To assess the effects of dapagliflozin plus saxagliptin plus metformin versus glimepiride plus metformin on liver fat (proton density fat fraction) and visceral and subcutaneous adipose tissue volumes over 52 weeks of treatment. MATERIALS AND METHODS: This was a magnetic resonance imaging substudy of a 52-week, multicentre, randomized, double-blind, parallel-group trial that evaluated the efficacy and safety of dapagliflozin 10 mg/day plus saxagliptin 5 mg/day versus titrated glimepiride 1-6 mg (1, 2, 3, 4 or 6 mg) in 82 patients with type 2 diabetes (HbA1c 7.5%-10.5%) on metformin ≥1500 mg/day background. Analyses were exploratory and not controlled for multiplicity; P-values are nominal. RESULTS: Magnetic resonance imaging was performed on 59 patients; liver fat and adipose tissue volumes were analysed for 59 and 57 patients, respectively. There was a significant >30% reduction from baseline in liver fat (P = 0.007) and >10% reduction in adipose tissue volumes (P < 0.01) with dapagliflozin plus saxagliptin plus metformin at week 52 versus glimepiride plus metformin. In the full-study population, dapagliflozin plus saxagliptin plus metformin decreased body weight and serum alanine aminotransferase and aspartate aminotransferase levels over 52 weeks. CONCLUSIONS: Dapagliflozin plus saxagliptin significantly decreased liver fat and adipose tissue volume versus glimepiride, and reduced serum liver enzyme levels, indicating a favourable metabolic profile of dapagliflozin plus saxagliptin in patients with type 2 diabetes on metformin therapy.

Consensus-based technical recommendations for clinical translation of renal T1 and T2 mapping MRI.

To develop technical recommendations on the acquisition and post-processing of renal longitudinal (T1) and transverse (T2) relaxation time mapping. A multidisciplinary panel consisting of 18 experts in the field of renal T1 and T2 mapping participated in a consensus project, which was initiated by the European Cooperation in Science and Technology Action PARENCHIMA CA16103. Consensus recommendations were formulated using a two-step modified Delphi method. The first survey consisted of 56 items on T1 mapping, of which 4 reached the pre-defined consensus threshold of 75% or higher. The second survey was expanded to include both T1 and T2 mapping, and consisted of 54 items of which 32 reached consensus. Recommendations based were formulated on hardware, patient preparation, acquisition, analysis and reporting. Consensus-based technical recommendations for renal T1 and T2 mapping were formulated. However, there was considerable lack of consensus for renal T1 and particularly renal T2 mapping, to some extent surprising considering the long history of relaxometry in MRI, highlighting key knowledge gaps that require further work. This paper should be regarded as a first step in a long-term evidence-based iterative process towards ever increasing harmonization of scan protocols across sites, to ultimately facilitate clinical implementation.

Variable flip angle 3D ultrashort echo time (UTE) T1 mapping of mouse lung: A repeatability assessment.

BACKGROUND: Lung T1 is a potential translational biomarker of lung disease. The precision and repeatability of variable flip angle (VFA) T1 mapping using modern 3D ultrashort echo time (UTE) imaging of the whole lung needs to be established before it can be used to assess response to disease and therapy. PURPOSE: To evaluate the feasibility of regional lung T1 quantification with VFA 3D-UTE and to investigate long- and short-term T1 repeatability in the lungs of naive mice. STUDY TYPE: Prospective preclinical animal study. POPULATION: Eight naive mice and phantoms. FIELD STRENGTH/SEQUENCE: 3D free-breathing radial UTE (8 µs) at 4.7T. ASSESSMENT: VFA 3D-UTE T1 calculations were validated against T1 values measured with inversion recovery (IR) in phantoms. Lung T1 and proton density (S0 ) measurements of whole lung and muscle were repeated five times over 1 month in free-breathing naive mice. Two consecutive T1 measurements were performed during one of the imaging sessions. STATISTICAL TESTS: Agreement in T1 between VFA 3D-UTE and IR in phantoms was assessed using Bland-Altman and Pearson 's correlation analysis. The T1 repeatability in mice was evaluated using coefficient of variation (CV), repeated-measures analysis of variance (ANOVA), and paired t-test. RESULTS: Good T1 agreement between the VFA 3D-UTE and IR methods was found in phantoms. T1 in lung and muscle showed a 5% and 3% CV (1255 ± 63 msec and 1432 ± 42 msec, respectively, mean ± SD) with no changes in T1 or S0 over a month. Consecutive measurements resulted in an increase of 2% in both lung T1 and S0 . DATA CONCLUSION: VFA 3D-UTE shows promise as a reliable T1 mapping method that enables full lung coverage, high signal-to-noise ratio (∼25), and spatial resolution (300 µm) in freely breathing animals. The precision of the VFA 3D-UTE method will enable better design and powering of studies. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

Magnetic resonance imaging biomarkers for chronic kidney disease: a position paper from the European Cooperation in Science and Technology Action PARENCHIMA.

Functional renal magnetic resonance imaging (MRI) has seen a number of recent advances, and techniques are now available that can generate quantitative imaging biomarkers with the potential to improve the management of kidney disease. Such biomarkers are sensitive to changes in renal blood flow, tissue perfusion, oxygenation and microstructure (including inflammation and fibrosis), processes that are important in a range of renal diseases including chronic kidney disease. However, several challenges remain to move these techniques towards clinical adoption, from technical validation through biological and clinical validation, to demonstration of cost-effectiveness and regulatory qualification. To address these challenges, the European Cooperation in Science and Technology Action PARENCHIMA was initiated in early 2017. PARENCHIMA is a multidisciplinary pan-European network with an overarching aim of eliminating the main barriers to the broader evaluation, commercial exploitation and clinical use of renal MRI biomarkers. This position paper lays out PARENCHIMA's vision on key clinical questions that MRI must address to become more widely used in patients with kidney disease, first within research settings and ultimately in clinical practice. We then present a series of practical recommendations to accelerate the study and translation of these techniques.

Evaluation of carotid plaque inflammation in patients with active rheumatoid arthritis using (18)F-fluorodeoxyglucose PET-CT and MRI: a pilot study.

BACKGROUND: Rheumatoid arthritis is associated with a 50% increased risk in cardiovascular mortality. Inflammation is thought to accelerate atherosclerosis and might also lead to an inflammatory rupture-prone plaque phenotype. We tested the hypothesis that patients with active rheumatoid arthritis also have carotid plaque inflammation and that plaque inflammation correlates with clinical and serological markers of inflammation. METHODS: Patients with active rheumatoid arthritis, defined as the Disease Activity Score in 28 joints (DAS28) score of more than 3·2, were recruited to a single centre study in the UK. Patients with carotid plaque on ultrasound underwent carotid MRI followed by (18)F-fluorodeoxyglucose ((18)F-FDG) PET-CT. Scans were co-registered and analysed by a physicist, masked to clinical information. The maximum standardised uptake values (SUV(max)) were measured in the plaque area. The association of SUV with DAS28, C-reactive protein, and CD4+CD28- T-cell frequency was tested with non-parametric statistics. Ethics approval and informed consent were obtained. FINDINGS: Scans were done in 13 patients, nine of whom were women. Median age was 60 years (IQR 57-65), disease duration was 11 years (6-25), and DAS28 score was 4·52 (4·32-5·13). None had a history or symptoms of clinical cardiovascular disease or took statins. All plaques caused less than 70% stenosis, and tracer uptake in plaque was seen on PET in all 13 patients. Median SUV(max) was 2·18 (IQR 2·00-2·65), and all cases had an SUV(max) greater than 1·6 (the threshold for defining carotid plaque inflammation). There was a significant association with SUV(max) and C-reactive protein (r=0·58, p=0·04) and quartiles of CD4+CD28- T-cell frequency (p=0·045), but not with low-density lipoprotein concentrations (r=-0·49, p=0·09) or DAS28 score (r=0·38, p=0·20). No association was found with age (r=0·13, p=0·69) or sex (p=0·64). INTERPRETATION: In this small pilot study, plaque inflammation was seen in all patients and correlated with C-reactive protein. Whether this finding represents simultaneous joint and plaque inflammation, which might improve on treatment of joint disease, remains to be determined. CD4+CD28- T-cells are known to predict cardiovascular events in patients with angina. Their association with plaque inflammation in this study suggests a possible role in cardiovascular risk prediction in rheumatoid arthritis. Larger studies are warranted to investigate these findings further. FUNDING: North West England MRC Clinical Pharmacology and Therapeutics Clinical Research Fellowship, National Institute for Health Research, AstraZeneca-University of Manchester Strategic Alliance Fund.

COPD Patients Have Short Lung Magnetic Resonance T1 Relaxation Time.

Magnetic resonance imaging (MRI) may provide attractive biomarkers for assessment of pulmonary disease in clinical trials as it is free from ionizing radiation, minimally invasive and allows regional information. The aim of this study was to characterize lung MRI T1 relaxation time as a biomarker of chronic obstructive pulmonary disease (COPD); and specifically its relationship to smoking history, computed tomography (CT), and pulmonary function test (PFT) measurements in comparison to healthy age-matched controls. Lung T1 and inter-quartile range (IQR) of T1 maps from 24 COPD subjects and 12 healthy age-matched non-smokers were retrospectively analyzed from an institutional review board approved study. The subjects underwent PFTs and two separate MR imaging sessions at 1.5 tesla to test T1 repeatability. CT scans were performed on the COPD subjects. T1 repeatability (intraclass correlation coefficient) was 0.72 for repeated scans acquired on two visits. The lung T1 was significantly shorter (p < 0.0001) and T1 IQR was significantly larger (p = 0.0002) for the COPD subjects compared to healthy controls. Lung T1 significantly (p = 0.001) correlated with lung density assessed with CT. Strong significant correlations (p < 0.0001) between lung T1 and all PFT measurements were observed. Cigarette exposure did not correlate with lung T1 in COPD subjects. In conclusion, lung MRI T1 mapping shows potential as a repeatable, radiation free, non-invasive imaging technique in the evaluation of COPD.

Assessment of gadoxetate DCE-MRI as a biomarker of hepatobiliary transporter inhibition.

Drug-induced liver injury (DILI) is a clinically important adverse drug reaction, which prevents the development of many otherwise safe and effective new drugs. Currently, there is a lack of sensitive and specific biomarkers that can be used to predict, assess and manage this toxicity. The aim of this work was to evaluate gadoxetate-enhanced MRI as a potential novel biomarker of hepatobiliary transporter inhibition in the rat. Initially, the volume fraction of extracellular space in the liver was determined using gadopentetate to enable an estimation of the gadoxetate concentration in hepatocytes. Using this information, a compartmental model was developed to characterise the pharmacokinetics of hepatic uptake and biliary excretion of gadoxetate. Subsequently, we explored the impact of an investigational hepatobiliary transporter inhibitor on the parameters of the model in vivo in rats. The investigational hepatobiliary transporter inhibitor reduced both the rate of uptake of gadoxetate into the hepatocyte, k1 , and the Michaelis-Menten constant, Vmax , characterising its excretion into bile, whereas KM values for biliary efflux were increased. These effects were dose dependent and correlated with effects on plasma chemistry markers of liver dysfunction, in particular bilirubin and bile acids. These results indicate that gadoxetate-enhanced MRI provides a novel functional biomarker of inhibition of transporter-mediated hepatic uptake and clearance in the rat. Since gadoxetate is used clinically, the technology has the potential to provide a translatable biomarker of drug-induced perturbation of hepatic transporters that may also be useful in humans to explore deleterious functional alterations caused by transporter inhibition.

Magnetic Resonance Imaging in Clinical Trials of Diabetic Kidney Disease.

Chronic kidney disease (CKD) associated with diabetes mellitus (DM) (known as diabetic kidney disease, DKD) is a serious and growing healthcare problem worldwide. In DM patients, DKD is generally diagnosed based on the presence of albuminuria and a reduced glomerular filtration rate. Diagnosis rarely includes an invasive kidney biopsy, although DKD has some characteristic histological features, and kidney fibrosis and nephron loss cause disease progression that eventually ends in kidney failure. Alternative sensitive and reliable non-invasive biomarkers are needed for DKD (and CKD in general) to improve timely diagnosis and aid disease monitoring without the need for a kidney biopsy. Such biomarkers may also serve as endpoints in clinical trials of new treatments. Non-invasive magnetic resonance imaging (MRI), particularly multiparametric MRI, may achieve these goals. In this article, we review emerging data on MRI techniques and their scientific, clinical, and economic value in DKD/CKD for diagnosis, assessment of disease pathogenesis and progression, and as potential biomarkers for clinical trial use that may also increase our understanding of the efficacy and mode(s) of action of potential DKD therapeutic interventions. We also consider how multi-site MRI studies are conducted and the challenges that should be addressed to increase wider application of MRI in DKD.

Use of In Vivo Imaging and Physiologically-Based Kinetic Modelling to Predict Hepatic Transporter Mediated Drug-Drug Interactions in Rats.

Gadoxetate, a magnetic resonance imaging (MRI) contrast agent, is a substrate of organic-anion-transporting polypeptide 1B1 and multidrug resistance-associated protein 2. Six drugs, with varying degrees of transporter inhibition, were used to assess gadoxetate dynamic contrast enhanced MRI biomarkers for transporter inhibition in rats. Prospective prediction of changes in gadoxetate systemic and liver AUC (AUCR), resulting from transporter modulation, were performed by physiologically-based pharmacokinetic (PBPK) modelling. A tracer-kinetic model was used to estimate rate constants for hepatic uptake (khe), and biliary excretion (kbh). The observed median fold-decreases in gadoxetate liver AUC were 3.8- and 1.5-fold for ciclosporin and rifampicin, respectively. Ketoconazole unexpectedly decreased systemic and liver gadoxetate AUCs; the remaining drugs investigated (asunaprevir, bosentan, and pioglitazone) caused marginal changes. Ciclosporin decreased gadoxetate khe and kbh by 3.78 and 0.09 mL/min/mL, while decreases for rifampicin were 7.20 and 0.07 mL/min/mL, respectively. The relative decrease in khe (e.g., 96% for ciclosporin) was similar to PBPK-predicted inhibition of uptake (97-98%). PBPK modelling correctly predicted changes in gadoxetate systemic AUCR, whereas underprediction of decreases in liver AUCs was evident. The current study illustrates the modelling framework and integration of liver imaging data, PBPK, and tracer-kinetic models for prospective quantification of hepatic transporter-mediated DDI in humans.

Liver Investigation: Testing Marker Utility in Steatohepatitis (LITMUS): Assessment & validation of imaging modality performance across the NAFLD spectrum in a prospectively recruited cohort study (the LITMUS imaging study): Study protocol.

Non-alcoholic fatty liver disease (NAFLD) is the liver manifestation of the metabolic syndrome with global prevalence reaching epidemic levels. Despite the high disease burden in the population only a small proportion of those with NAFLD will develop progressive liver disease, for which there is currently no approved pharmacotherapy. Identifying those who are at risk of progressive NAFLD currently requires a liver biopsy which is problematic. Firstly, liver biopsy is invasive and therefore not appropriate for use in a condition like NAFLD that affects a large proportion of the population. Secondly, biopsy is limited by sampling and observer dependent variability which can lead to misclassification of disease severity. Non-invasive biomarkers are therefore needed to replace liver biopsy in the assessment of NAFLD. Our study addresses this unmet need. The LITMUS Imaging Study is a prospectively recruited multi-centre cohort study evaluating magnetic resonance imaging and elastography, and ultrasound elastography against liver histology as the reference standard. Imaging biomarkers and biopsy are acquired within a 100-day window. The study employs standardised processes for imaging data collection and analysis as well as a real time central monitoring and quality control process for all the data submitted for analysis. It is anticipated that the high-quality data generated from this study will underpin changes in clinical practice for the benefit of people with NAFLD. Study Registration: clinicaltrials.gov: NCT05479721.

In vivo imaging of lipid storage and regression in diet-induced obesity during nutrition manipulation.

Changes in adipose tissue distribution and ectopic fat storage in, liver and skeletal muscle tissue impact whole body insulin sensitivity in both humans and experimental animals. Numerous mouse models of obesity, insulin resistance, and diabetes exist; however, current methods to assess mouse phenotypes commonly involve direct harvesting of the tissues of interest, precluding the possibility of repeated measurements in the same animal. In this study, we demonstrate that whole body 3-D imaging of body fat composition can be used to analyze distribution as well as redistribution of fat after intervention by repeated assessment of intrahepatocellular lipids (IHCL), intra-abdominal, subcutaneous, and total adipose tissue (IAT, SAT, and TAT) and brown adipose tissue (BAT). C57BL/6J mice fed a cafeteria diet for 16 wk were compared with mice fed standard chow for 16 wk and mice switched from café diet to standard chow after 12 wk. MRI determinations were made at 9 and 15 wk, and autopsy was performed at 16 wk. There was a strong correlation between MRI-calculated weights in vivo at 15 wk and measured weights at 16 wk ex vivo for IAT (r = 0.99), BAT (r = 0.93), and IHCL (r = 0.97). IHCL and plasma insulin increased steeply relative to body weight at body weights above 45 g. This study demonstrates that the use of 3-D imaging to assess body fat composition may allow substantial reductions in animal usage. The dietary interventions indicated that a marked metabolic deterioration occurred when the mice had gained a certain fat mass.

Cardiac imaging approaches to evaluate drug-induced myocardial dysfunction.

The ability to make informed benefit-risk assessments for potentially cardiotoxic new compounds is of considerable interest and importance at the public health, drug development, and individual patient levels. Cardiac imaging approaches in the evaluation of drug-induced myocardial dysfunction will likely play an increasing role. However, the optimal choice of myocardial imaging modality and the recommended frequency of monitoring are undefined. These decisions are complicated by the array of imaging techniques, which have varying sensitivities, specificities, availabilities, local expertise, safety, and costs, and by the variable time-course of tissue damage, functional myocardial depression, or recovery of function. This White Paper summarizes scientific discussions of members of the Cardiac Safety Research Consortium on the main factors to consider when selecting nonclinical and clinical cardiac function imaging techniques in drug development. We focus on 3 commonly used imaging modalities in the evaluation of cardiac function: echocardiography, magnetic resonance imaging, and radionuclide (nuclear) imaging and highlight areas for future research.

Fatty acids in multiple circulating lipid fractions reflects the composition of liver triglycerides in humans.

BACKGROUND AND AIMS: Fatty acids (e.g. 16:1n-7) and desaturase indices (e.g. stearoyl-CoA desaturase, SCD) in plasma cholesteryl esters (CE) and phospholipids (PL) are used as biomarkers of dietary fat quality and lipid metabolism and are associated with disease outcomes. Endogenously produced circulating fatty acids are believed to reflect composition of the liver, yet little data exist to support such relationship. We investigated associations between circulating fatty acids and fatty acids within the liver. METHODS: Liver biopsies and blood were collected from n = 60 patients with non-alcoholic fatty liver disease. Fatty acids in CE, PL and triglycerides (TG) in plasma and liver were analyzed using gas chromatography. Associations were assessed using Spearman rank correlations. RESULTS: Overall, fatty acids and desaturase indices in plasma PL and TG showed moderate-strong correlations with fatty acids and desaturase indices in corresponding lipid fractions in liver. For plasma CE, 16:1n-7 and SCD were correlated with 16:1n-7 and SCD in liver CE. Noteworthy, fatty acids in plasma CE and PL also showed moderate-strong correlations with fatty acids in liver TG (e.g. r = 0.82-0.87 for 16:1n-7 and r = 0.77 for SCD). CONCLUSION: We demonstrate that fatty acids in circulating lipid fractions, including CE, TG and PL, reflects the composition of liver TG in humans, suggesting that circulating fatty acids might be useful biomarkers for the fatty acid composition of the liver. As liver tissue is rarely available in cohort studies, our findings could enhance our understanding of plasma fatty acids as markers of hepatic lipid metabolism and their links to metabolic diseases.

Multiparametric magnetic resonance imaging allows non-invasive functional and structural evaluation of diabetic kidney disease.

Background: We sought to develop a novel non-contrast multiparametric MRI (mpMRI) protocol employing several complementary techniques in a single scan session for a comprehensive functional and structural evaluation of diabetic kidney disease (DKD). Methods: In the cross-sectional part of this prospective observational study, 38 subjects ages 18‒79 years with type 2 diabetes and DKD [estimated glomerular filtration rate (eGFR) 15‒60 mL/min/1.73 m2] and 20 age- and gender-matched healthy volunteers (HVs) underwent mpMRI. Repeat mpMRI was performed on 23 DKD subjects and 10 HVs. By measured GFR (mGFR), 2 DKD subjects had GFR stage G2, 16 stage G3 and 20 stage G4/G5. A wide range of MRI biomarkers associated with kidney haemodynamics, oxygenation and macro/microstructure were evaluated. Their optimal sensitivity, specificity and repeatability to differentiate diabetic versus healthy kidneys and categorize various stages of disease as well as their correlation with mGFR/albuminuria was assessed. Results: Several MRI biomarkers differentiated diabetic from healthy kidneys and distinct GFR stages (G3 versus G4/G5); mean arterial flow (MAF) was the strongest predictor (sensitivity 0.94 and 1.0, specificity 1.00 and 0.69; P = .04 and .004, respectively). Parameters significantly correlating with mGFR were specific measures of kidney haemodynamics, oxygenation, microstructure and macrostructure, with MAF being the strongest univariate predictor (r = 0.92; P < .0001). Conclusions: A comprehensive and repeatable non-contrast mpMRI protocol was developed that, as a single, non-invasive tool, allows functional and structural assessment of DKD, which has the potential to provide valuable insights into underlying pathophysiology, disease progression and analysis of efficacy/mode of action of therapeutic interventions in DKD.

Randomised clinical trial: semaglutide versus placebo reduced liver steatosis but not liver stiffness in subjects with non-alcoholic fatty liver disease assessed by magnetic resonance imaging.

BACKGROUND: Glucagon-like peptide-1 receptor agonists may be a treatment option in patients with non-alcoholic fatty liver disease (NAFLD). AIMS: To investigate the effects of semaglutide on liver stiffness and liver fat in subjects with NAFLD using non-invasive magnetic resonance imaging (MRI) methods. METHODS: This randomised, double-blind, placebo-controlled trial enrolled subjects with liver stiffness 2.50-4.63 kPa by magnetic resonance elastography (MRE) and liver steatosis ≥10% by MRI proton density fat fraction (MRI-PDFF). The primary endpoint was change from baseline to week 48 in liver stiffness assessed by MRE. RESULTS: Sixty-seven subjects were randomised to once-daily subcutaneous semaglutide 0.4 mg (n = 34) or placebo (n = 33). Change from baseline in liver stiffness was not significantly different between semaglutide and placebo at week 48 (estimated treatment ratio 0.96 (95% CI 0.89, 1.03; P = 0.2798); significant differences in liver stiffness were not observed at weeks 24 or 72. Reductions in liver steatosis were significantly greater with semaglutide (estimated treatment ratios: 0.70 [0.59, 0.84], P = 0.0002; 0.47 [0.36, 0.60], P < 0.0001; and 0.50 [0.39, 0.66], P < 0.0001) and more subjects achieved a ≥ 30% reduction in liver fat content with semaglutide at weeks 24, 48 and 72, (all P < 0.001). Decreases in liver enzymes, body weight and HbA1c were also observed with semaglutide. CONCLUSIONS: The change in liver stiffness in subjects with NAFLD was not significantly different between semaglutide and placebo. However, semaglutide significantly reduced liver steatosis compared with placebo which, together with improvements in liver enzymes and metabolic parameters, suggests a positive impact on disease activity and metabolic profile. ClinicalTrials.gov identifier: NCT03357380.