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Background & Aims Tools for the non-invasive diagnosis of non-alcoholic steatohepatitis (NASH) in morbidly obese patients with suspected non-alcoholic fatty liver disease (NAFLD) are an unmet clinical need. We prospectively compared the performance of transient elastography, MRI, and 3 serum scores for the diagnosis of NAFLD, grading of steatosis and detection of NASH in bariatric surgery candidates. Methods Of 186 patients screened, 152 underwent liver biopsy, which was used as a reference for NAFLD (steatosis [S]>5%), steatosis grading and NASH diagnosis. Biopsies were read by a single expert pathologist. MRI-based proton density fat fraction (MRI-PDFF) was measured in an open-bore, vertical field 1.0T scanner and controlled attenuation parameter (CAP) was measured by transient elastography, using the XL probe. Serum scores (SteatoTest, hepatic steatosis index and fatty liver index) were also calculated. Results The applicability of MRI was better than that of FibroScan (98% vs. 79%; p 5%, S>33%, S>66% and NASH, respectively. Transient elastography had an AUROC of 0.80 for significant fibrosis (F0-F1 vs. F2-F3). MRI-PDFF had AUROCs of 0.97, 0.95, 0.92 and 0.84 for S>5%, S>33%, S>66% and NASH, respectively. When compared head-to-head in the 97 patients with all valid tests available, MRI-PDFF outperformed CAP for grading steatosis (S>33%, AUROC 0.97 vs. 0.78; p 66%, AUROC 0.93 vs. 0.75; p = 0.0015) and diagnosing NASH (AUROC 0.82 vs. 0.68; p = 0.0056). When compared in “intention to diagnose” analysis, MRI-PDFF outperformed CAP, hepatic steatosis index and fatty liver index for grading steatosis (S>5%, S>33% and S>66%). Conclusion MRI-PDFF outperforms CAP for diagnosing NAFLD, grading steatosis and excluding NASH in morbidly obese patients undergoing bariatric surgery. Lay summary Non-invasive tests for detecting fatty liver and steatohepatitis, the active form of the disease, have not been well studied in obese patients who are candidates for bariatric surgery. The most popular tests for this purpose are Fibroscan, which can be used to measure the controlled attenuation parameter (CAP), and magnetic resonance imaging, which can be used to measure the proton density fat fraction (MRI-PDFF). We found that, when taking liver biopsy as a reference, MRI-PDFF performed better than CAP for detecting and grading fatty liver as well as excluding steatohepatitis in morbidly obese patients undergoing bariatric surgery., Graphical abstract, Highlights • NAFLD/NASH is common in morbidly obese patients undergoing bariatric surgery. • Non-invasive diagnosis of NAFLD/NASH is an unmet need in this population. • We compared MRI-PDFF, CAP and serum scores for grading steatosis and diagnosing NASH, using liver biopsy as a reference. • Applicability of magnetic resonance imaging was better than that of Fibroscan. • MRI-PDFF outperformed CAP for diagnosing and grading steatosis, as well as excluding NASH.

The water proton longitudinal relaxation time, T1, is a common and useful MR parameter in nephrology research. Here we provide three step-by-step T1-mapping protocols suitable for different types of nephrology research. Firstly, we provide a single-slice 2D saturation recovery protocol suitable for studies of global pathology, where whole-kidney coverage is unnecessary. Secondly, we provide an inversion recovery type imaging protocol that may be optimized for specific kidney disease applications. Finally, we also provide imaging protocol for small animal kidney imaging in a clinical scanner.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This analysis protocol chapter is complemented by two separate chapters describing the basic concept and experimental procedure.

In renal MRI, measurement of the T1 relaxation time of water molecules may provide a valuable biomarker for a variety of pathological conditions. Due to its sensitivity to the tissue microenvironment, T1 has gained substantial interest for noninvasive imaging of renal pathology, including inflammation and fibrosis. In this chapter, we will discuss the basic concept of T1 mapping and different T1 measurement techniques and we will provide an overview of emerging preclinical applications of T1 for imaging of kidney disease.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by two separate chapters describing the experimental procedure and data analysis.

Purpose To determine the relationship of liver fibrosis, inflammation, and steatosis with the magnetic resonance (MR) viscoelastic and diffusion parameters in patients with chronic liver disease and to compare the diagnostic accuracy of the imaging parameters in staging liver fibrosis. Materials and Methods Consecutive patients with chronic liver disease scheduled for liver biopsy were prospectively recruited from November 2010 to October 2012 for this institutional review board-approved study after they provided written informed consent. Sixty-eight patients underwent three-dimensional MR elastography and intravoxel incoherent motion diffusion-weighted MR imaging with a 1.5-T MR system. Fibrosis, inflammation, and steatosis were assessed with the METAVIR and steatosis, activity, and fibrosis (or SAF) scoring systems. Spearman correlation and multiple regression analyses were performed to determine the relationship between liver fibrosis, inflammation, steatosis, and alanine aminotransferase (ALT) levels and viscoelastic and diffusion parameters. The accuracy of three-dimensional MR elastography and diffusion-weighted MR imaging in the determination of fibrosis stage was assessed with Obuchowski measures. Results At multiple regression analysis, fibrosis was the only variable associated with viscoelastic parameters (β = 0.6, P < .001, R2 = 0.33 for shear modulus; β = 0.6, P < .001, R2 = 0.32 for elasticity). Fibrosis had a weaker independent association with the apparent diffusion coefficient (β = -0.3, P = .02, R2 = 0.33) than did steatosis (β = -0.5, P < .001, R2 = 0.33). Steatosis was the only factor independently associated with the pure diffusion coefficient (β = -0.4, P = .002, R2 = 0.22). Inflammation and ALT level were not associated with the viscoelastic or diffusion parameters. The diagnostic accuracy of fibrosis staging was significantly higher when measuring the shear modulus rather than the apparent diffusion coefficient (Obuchowski measures, 0.82 ± 0.04 vs 0.30 ± 0.06; P < .001). Conclusion Fibrosis is independently associated with the MR viscoelastic parameters and is less associated with the diffusion parameters than is steatosis. These results and those of diagnostic accuracy suggest that MR elastography should be preferred over diffusion-weighted MR imaging in the staging of liver fibrosis. © RSNA, 2016.

Background Fistulizing anoperineal lesions (FAPLs) are common and severe complications of Crohn’s disease (CD), exposing patients to the risk of anal sphincter alteration and permanent stoma. Due to the limited efficacy of current treatments, identifying new local therapies is mandatory. However, testing new treatments is currently limited because no relevant preclinical model of Crohn’s-like FAPL is available. Thus, a reliable and reproducible experimental model of FAPLs is needed to assess new therapeutic strategies. Methods Twenty-one rats received a rectal enema of 2,4,6-trinitrobenzensulfonic acid (TNBS) to induce proctitis. Seven days later, a transsphincteric fistula tract was created with a surgical thread, instilled with TNBS twice a week until its removal at day 7 (group 1), day 14 (group 2), or day 28 (group 3). In each rat, pelvic MRI was performed just before and 7 days after thread removal. Rats were sacrificed 7 days after thread removal for pathological assessment of the fistula tract. Results The optimal preclinical model was obtained in group 3. In this group, 7 days after thread removal, all animals (9 of 9) had a persistent fistula tract visible on MRI with T2-hypersignal (normalized T2 signal intensity: 2.36 ± 0.39 arbitrary units [a.u.] [2.08–2.81]) and elevation of the apparent diffusion coefficient (1.33 ± 0.16 10-3 millimeter squared per seconds [1.18–1.49]). The pathological examination of the fistula tract revealed acute and chronic inflammation, granulations, fibrosis, epithelialization, and proctitis in the adjacent rectum. Conclusions This reproducible preclinical model could be used to assess the effectiveness of innovative treatments in perianal fistulizing CD.

Background In contrast to classical pulsed gradient diffusion-weighted MRI, oscillating gradient diffusion-weighted MR imaging (DWI) is sensitive to short distance diffusion changes at the intracellular level. Purpose To compare the diagnostic performance of pulsed and oscillating DWI for characterizing hepatocellular nodules in a rat model of hepatic cirrhosis. Study type Prospective, experimental study. Animal model Cirrhosis was induced by weekly intraperitoneal injection of diethylnitrosamine in Wistar rats. Field strength/sequence Ex vivo liver MRI was performed at 7T with T1 -weighted, T2 -weighted, pulsed, and oscillating gradient diffusion-weighted sequences. Assessment Apparent diffusion coefficient from pulsed (ADCpulsed ) and oscillating gradient (ADCoscillating ) sequences was calculated in 82 nodules identified on the T1 /T2 -weighted images and on pathological examination. Two pathologists classified the nodules in three categories: benign (regenerative and low-grade dysplastic nodules), with intermediate malignancy (high-grade dysplastic nodules and early hepatocellular carcinomas) and overtly malignant (progressed hepatocellular carcinomas). Statistical tests Differences between groups were assessed with Kruskal-Wallis and Mann-Whitney tests. Results ADC, mainly ADCoscillating , increased in the group of nodules with intermediate malignancy (ADCpulsed : 0.75 ± 0.25 × 10-3 mm2 /s vs. 0.64 ± 0.07 × 10-3 mm2 /s in benign nodules, P = 0.025; ADCoscillating : 0.81 ± 0.20 × 10-3 mm2 /s vs. 0.65 ± 0.13 × 10-3 mm2 /s, P = 0.0008) and ADCpulsed decreased in the group of progressed hepatocellular carcinomas (ADCpulsed : 0.60 ± 0.08 × 10-3 mm2 /s, P = 0.042; ADCoscillating : 0.68 ± 0.08 × 10-3 mm2 /s, P = 0.1). Data conclusion ADC during hepatocarcinogenesis in rats increased in nodules with intermediate malignancy and decreased in progressed hepatocellular carcinomas. Our results suggest that oscillating gradient DWI is more sensitive to the early steps of hepatocarcinogenesis and might be useful for differentiating between high-grade dysplastic nodules / early hepatocellular carcinomas and regenerating nodules / low-grade dysplastic nodules. Level of evidence 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:1065-1074.

Purpose: The aim of the study was to investigate the potential of diffusion-weighted magnetic resonance imaging (DW-MRI) and 3′-dexoy-3′-[18F]fluorothymidine ([18F]FLT) positron emission tomography (PET) as early biomarkers of treatment response of 5-fluorouracil (5-FU) in a syngeneic rat model of colorectal cancer liver metastases. Procedures: Wag/Rij rats with intrahepatic syngeneic CC531 tumors were treated with 5-FU (15, 30, or 60 mg/kg in weekly intervals). Before treatment and at days 1, 3, 7, and 14 after treatment rats underwent DW-MRI and [18F]FLT PET. Tumors were analyzed immunohistochemically for Ki67, TK1, and ENT1 expression. Results: 5-FU inhibited the growth of CC531 tumors in a dose-dependent manner. Immunohistochemical analysis did not show significant changes in Ki67, TK1, and ENT1 expression. However, [18F]FLT SUVmean and SUVmax were significantly increased at days 4 and 7 after treatment with 5-FU (60 mg/kg) and returned to baseline at day 14 (SUVmax at days −1, 4, 7, and 14 was 1.1 ± 0.1, 2.3 ± 0.5, 2.3 ± 0.6, and 1.5 ± 0.4, respectively). No changes in [18F]FLT uptake were observed in the nontreated animals. Furthermore, the apparent diffusion coefficient (ADCmean) did not change in 5-FU-treated rats compared to untreated rats. Conclusion: This study suggests that 5-FU treatment induces a flare in [18F]FLT uptake of responsive CC531 tumors in the liver, while the ADCmean did not change significantly. Future studies in larger groups are warranted to further investigate whether [18F]FLT PET can discriminate between disease progression and treatment response.

The viscoelastic properties of the liver and spleen can be assessed with magnetic resonance elastography (MRE). Several actuators, MRI acquisition sequences and reconstruction algorithms have been proposed for this purpose. Reproducible results are obtained, especially when the examination is performed in standard conditions with the patient fasting. Accurate staging of liver fibrosis can be obtained by measuring liver stiffness or elasticity with MRE. Moreover, emerging evidence shows that assessing the tissue viscous parameters with MRE is useful for characterizing liver inflammation, non-alcoholic steatohepatitis, hepatic congestion, portal hypertension, and hepatic tumors. Further advances such as multifrequency acquisitions and compression-sensitive MRE may provide novel quantitative markers of hepatic and splenic mechanical properties that may improve the diagnosis of hepatic and splenic diseases.

Changes in the expression of hepatocyte membrane transporters in advanced fibrosis decrease the hepatic transport function of organic anions. The aim of our study was to assess if these changes can be evaluated with pharmacokinetic analysis of the hepatobiliary transport of the MR contrast agent gadoxetate. Dynamic gadoxetate-enhanced MRI was performed in 17 rats with advanced fibrosis and 8 normal rats. After deconvolution, hepatocyte three-compartmental analysis was performed to calculate the hepatocyte influx, biliary efflux and sinusoidal backflux rates. The expression of Oatp1a1, Mrp2 and Mrp3 organic anion membrane transporters was assessed with reverse transcription polymerase chain reaction. In the rats with advanced fibrosis, the influx and efflux rates of gadoxetate decreased and the backflux rate increased significantly (p = 0.003, 0.041 and 0.010, respectively). Significant correlations were found between influx and Oatp1a1 expression (r = 0.78, p

Liver perfusion imaging is a quantitative functional investigation. Liver perfusion imaging is complicated because of the liver's dual vascular supply, artefacts due to respiratory movements and the fenestrated sinusoidal capillaries which allow the contrast medium to diffuse out. Liver perfusion can be examined by ultrasound, CT or MRI: each technique has its limitations and specific features. The major indications in hepatology are oncology (detection, characterization and tumor response) and non-invasive investigation of patients with chronic liver disease. Work is needed to standardize acquisition and modeling methods to allow wider use of results and more widespread use of the technique.

Intestinal fibrosis is a common complication of inflammatory bowel disease caused by an excessive deposition of extracellular matrix components. Currently, there are no reliable scores to identify early stages of fibrosis prior to clinical symptoms. Potential biomarkers of intestinal fibrosis, including gene variants, serum microRNAs, serum extracellular matrix proteins or circulating cells (i.e. fibrocytes) have shown neither harmonious results nor specific for fibrostenosis on heterogeneous patients’ cohorts. In this work, we develop reproducible mathematical models of intestinal fibrosis activity based on continuous wavelet-based analysis of univariate and bivariate time series derived from magnetic resonance imaging on irradiated-rat models of rectitis. This approach enable us to provide clinicians with a non-invasive and reliable score of fibrosis state necessary prior to make any decision on the course of a patient’s treatment.

Assess the effect of fat deposition on the MRI diffusion coefficients in lipid emulsion-based phantoms and patients with proven isolated liver steatosis.Diffusion-weighted MRI with 11 b values from 0-500 s/mm(2) was performed in phantoms (fat fractions 0-18 %) with and without fat suppression and in 19 patients with normal liver (n = 14) or isolated liver steatosis (n = 5) proven by histopathology. The apparent, pure and perfusion-related diffusion coefficients and the perfusion fraction were measured. Spearman correlation coefficient and Mann-Whitney U test were used for comparisons.A strong correlation between the apparent and pure diffusion coefficients and fat fractions was seen in phantoms. The pure diffusion coefficient decreased significantly in patients with liver steatosis (0.96 ± 0.16 × 10(-3) mm(2)/s versus 1.18 ± 0.09 × 10(-3) mm(2)/s in normal liver, P = 0.005), whereas the decrease in apparent diffusion coefficient did not reach statistical significance (1.26 ± 0.25 × 10(-3) mm(2)/s versus 1.41 ± 0.14 × 10(-3) mm(2)/s in normal liver, P = 0.298).Fat deposition decreases the apparent and pure diffusion coefficients in lipid emulsion-based phantoms and patients with isolated liver steatosis proven by histopathology.

assessed from 1 H MRS using point-resolved spectroscopy (PRESS) [TE=24ms; TR=2500ms; variable pulse power and optimized relaxation delay (VAPOR) water suppression; 27-m La nd 8-mL voxels in rats and mice, respectively] at 7T. Alterations in metabolites (Totally Automatic Robust Quantitation in NMR, TARQUIN) in tumors were characterized by increases in lipids (Lip1.3: 8.8–54.5mM for C6 and GL261) and decreases in NAA (1.3–2.0mM for RG2, GL261 and C6) and tCr (0.8–4.0mM for F98, RG2, GL261 and C6) in some models. F98, RG2, GL261 and C6 models all showed significantly decreased (p

Conventional MR imaging of the liver has a central role in the assessment of liver diseases. Diffusion-weighted MR imaging, MR elastography, and time-resolved dynamic contrast-enhanced MR imaging improve the anatomical information provided by conventional MR imaging and add quantitative functional information in diffuse and focal liver diseases. Particularly, accurate detection and characterization of liver fibrosis are feasible with quantitative MR elastography, detection of liver tumors is increased with diffusion-weighted MR imaging and time-resolved dynamic contrast-enhanced MR imaging, characterization of tumors can be improved with quantitative diffusion-weighted MR imaging and MR elastography. These methods also have the potential to provide adequate biomarkers for assessing the response to treatment. Currently, the main limitations of quantitative MR imaging are related to reproducibility, standardization, and/or limited clinical data. It is important to improve and standardize the quantitative MR methods and validate their role in large multicenter trials.

Angiogenesis is essential to tumour progression and a precise evaluation of angiogenesis is important for tumour early diagnosis and treatment. The quantitative and dynamic in vivo assessment of tumour angiogenesis can be achieved by molecular magnetic resonance imaging (mMRI). Vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) are the main regulatory systems in angiogenesis and have been used as hot targets for radionuclide-based molecular imaging. However, little research has been accomplished in targeting VEGF/VEGFRs by mMRI. In our study, we aimed to assess the expression of VEGFR2 in C6 gliomas by using a specific molecular probe with mMRI. The differential uptake of the probe conjugated to anti-VEGFR2 monoclonal antibody, shown by varied increases in T1 signal intensity during a 2 hr period, demonstrated the heterogeneous expression of VEGFR2 in different tumour regions. Microscopic fluorescence imaging, obtained for the biotin group in the probe with streptavidin-Cy3, along with staining for cellular VEGFR2 levels, laminin and CD45, confirmed the differential distribution of the probe which targeted VEGFR2 on endothelial cells. The angiogenesis process was also assessed using magnetic resonance angiography, which quantified tumour blood volume and provided a macroscopic view and a dynamic change of the correlation between tumour vasculature and VEGFR2 expression. Together these results suggest mMRI can be very useful in assessing and characterizing the expression of specific angiogenic markers in vivo and help evaluate angiogenesis associated with tumour progression.

Between 15,000 and 20,000 people are diagnosed each year with a primary malignant brain or central nervous system (CNS) tumor in the United States alone (1). Eighty percent of these tumors are gliomas, i.e. tumors originating from the glial cells of the brain, and especially Glioblastoma multiforme (GBM). GBM is the most aggressive glioma type, diagnosed in nearly 10,000 patients each year, and its prognosis is very low. In the best current treatment situation, only 5% of these patients survive the 3-year mark (1). This poor prognosis is due to several factors, such as the resistance to treatment of gliomas and the difficulty in obtaining an early and accurate diagnosis. A clearer understanding of the glioma microenvironment would certainly be crucial for a better diagnosis and an improved patient survival. Indeed, for clinicians to decide on an adequate treatment for the patient, tumor grading must be quick and precise (2), while being virtually non-invasive. From this point of view, non-invasive in vivo imaging tools such as magnetic resonance imaging (MRI) and angiography (MRA) are ideal modalities, since they can be used to assess glioma morphology, growth pattern and the angiogenesis process inherent to any tumor type (3). Morphological imaging can particularly provide detailed information on the tissue structure of the glioma and help the assessment of necrosis, which is characteristic of high-grade gliomas and poor prognosis (4). Diffuse infiltration is also interesting to assess, since gliomas are known to exhibit dramatic invasiveness and proliferation as soon as being grade II (5). MRA techniques can follow the vascular alterations brought by the glioma during its progression (6). Neovascularization is an event that distinguishes the moderately aggressive grade III from the GBM-like grade IV tumors (4, 7), and the nature of vascular alterations can also inform on the prognosis (8, 9). MRA would thus be an interesting imaging modality for the study of gliomas. We were also highly interested in comparing glioma models varying in their degree of malignancy and provide a characterization for these models as extensive as our MRI methods allow. The models that we chose, from slow-growing ethyl-nitrosourea (ENU)-induced gliomas (10) to more aggressive rodent C6, GL261, 9L/LacZ, RG2 and F98 glioma models, as well as the human U87 glioma model (11), are all considered as good glioma models. However, investigators have underlined the importance of using diverse tumor models during preclinical studies (12), since morphological or biochemical differences between models could potentially result in different treatment responses. It was thus in our interest to characterize these models as precisely as possible, to identify if they really are similar in their growth pattern, morphology and angiogenic behavior. A model of spontaneous chemically-induced gliomas was obtained by exposing pregnant females to ENU, which allowed us to study the transition between low-grade, slow-growing gliomas and high-grade tumors (13). Among the existing glioma cell lines, the C6 model has been widely used as a reliable model of GBM (14) and presenting high similarity with human glioma cells in the expression of genes involved in tumor progression (15). 9L/LacZ (16), F98 (11), GL261 (17) and RG2 (11) cells give rise to more aggressive, infiltrative and angiogenic gliomas. Finally, human U87 cells are considered highly tumorigenic and of high interest for angiogenesis studies (18). In summary, we used MRI and non-contrast-enhanced MRA techniques to comprehensively characterize diverse glioma models (ENU-induced, C6, F98, 9L/LacZ, GL261, RG2 and U87), as well as to show that these imaging techniques are sufficient to precisely depict glioma behavior in vivo.

The levels of Met, a tyrosine kinase receptor for the hepatocyte growth factor or scatter factor, are elevated during tissue regeneration, and can be used to assess tissue regeneration associated with engineered tissue grafts. This study involved the development and assessment of a novel magnetic resonance imaging (MRI) molecular probe for the in vivo detection of Met in an experimental rodent (rat) model of disease (C6 glioma). The implication of using these probes in tissue engineering is discussed. The molecular targeting agent we used in our study incorporated a magnetite-based dextran-coated nanoparticle backbone covalently bound to an anti-Met antibody. We used molecular MRI with an anti-Met probe to detect in vivo Met levels as a molecular marker for gliomas. Tumor regions were compared to normal tissue, and found to significantly (p

With increasing age, a subset of otherwise healthy individuals undergoes impairments in learning and memory that have been termed mild cognitive impairment (MCI). The enhanced neuronal activity associated with learning and memory requires increased cerebral blood flow (CBF) to specific brain regions. However, the interactions between cerebral blood flow and MCI remain unclear. In this study, we address whether baseline or hypercapnia-induced (increased blood CO2 levels) changes in CBF are modified with age, and whether these measures are predictive of cognitive status in rodents. Adult and aged rats were evaluated using a hippocampally-dependent task in a water maze. Aged rats were classified as memory-impaired or memory-intact based on performance comparisons with adult rats. Cerebral blood flow was assessed using flow-alternating inversion recovery (FAIR) magnetic resonance imaging (MRI), before and after breathing 10% CO2. The transition period between CO2 concentrations was examined with blood oxygen level dependent (BOLD) MRI. Separation of aged animals into memory-intact and impaired categories revealed increased basal perfusion in the dorsal hippocampus of memory-impaired versus memory-intact aged animals. Linear regression revealed that higher hippocampal perfusion was correlated with impaired memory in aged animals, and a logistic regression indicated that hippocampal perfusion predicted spatial memory ability. Several brain regions of aged rats demonstrated an attenuation of the perfusion increase normally observed in adult rats under hypercapnia. Memory-impaired animals were the primary contributor to this effect, as their perfusion response to hypercapnia was significantly reduced compared to adult animals. Aged, memory-intact animals were not significantly different from adults. BOLD MRI demonstrated a reduced response in aged animals to hypercapnia, with impaired animals being the primary contributor to the effect. A logistic regression model based on basal and hypercapnia perfusion correctly predicted cognitive status in 83.3% of animals tested. Our results indicate that age-related changes in vascular reactivity and perfusion are important contributing factors in memory impairment.

Brain dysfunction is frequently observed in sepsis as a consequence of changes in cerebral structure and metabolism, resulting in worse outcome and reduced life-quality of surviving patients. However, the mechanisms of sepsis-associated encephalopathy development and a better characterization of this syndrome in vivo are lacking. Here, we used magnetic resonance imaging (MRI) techniques to assess brain morphology and metabolism in a murine sepsis model (cecal ligation and puncture, CLP). Sham-operated and CLP mice were subjected to a complete MRI session at baseline, 6 and 24 h after surgery. Accumulation of vasogenic edematic fluid at the base of the brain was observed in T2-weighted image at 6 and 24 h after CLP. Also, the water apparent diffusion coefficients in both hippocampus and cortex were decreased, suggesting a cytotoxic edema in brains of nonsurvival septic animals. Moreover, the N-acetylaspartate/choline ratio was reduced in brains of septic mice, indicating neuronal damage. In conclusion, noninvasive assessment by MRI allowed the identification of new aspects of brain damage in sepsis, including cytotoxic and vasogenic edema as well as neuronal damage. These findings highlight the potential applications of MRI techniques for the diagnostic and therapeutic studies in sepsis.

The prognosis of patients who are diagnosed with glioblastoma multiforme is very poor, due to the difficulty of an early and accurate diagnosis and the lack of currently efficient therapeutic compounds. The efficacy of phenyl-tert-butylnitrone (PBN) as a potential anti-glioma therapeutic drug was assessed by magnetic resonance (MR) imaging (T(1)/T(2)-weighted imaging) and MR angiography (time-of-flight imaging, in conjunction with a Mathematica-based program) methods by monitoring morphologic properties, growth patterns, and angiogenic behaviors of a moderately aggressive rat C6 glioma model. MR results from untreated rats showed the diffusive invasiveness of C6 gliomas, with some associated angiogenesis. PBN administration as a pretreatment was found to clearly induce a decrease in growth rate and tumor regression as well as preventing angiogenesis. This compound even had a 40% efficiency in reducing well-established tumors. MR findings rivaled those from histology and angiogenesis marker immunostaining evaluations. In this study we demonstrated the efficiency of PBN as a potential anti-glioma drug and found it to inhibit tumor cell proliferation and prevent vascular alterations in early stages of glioma progression. The MR methods that we used also proved to be particularly suitable in following the angiogenic behavior and treatment response of a potential anti-glioma agent in a rat C6 glioma model.

International audience; To compare the value of enhancement and pharmacokinetic parameters measured at dynamic gadoxetate-enhanced magnetic resonance (MR) imaging in determining hepatic organic anion transporter expression in control rats and rats with advanced liver fibrosis.Institutional animal review board approval was received before the study began. Advanced liver fibrosis was created in rats by means of carbon tetrachloride injections over an 8-week period. In 17 rats with liver fibrosis and eight control rats, dynamic gadoxetate-enhanced MR images of the liver were obtained during 1 hour after injection of 0.025 mmol gadoxetate per kilogram of body weight. Enhancement parameters (maximum enhancement [Emax], time to peak [Tmax], and elimination half-life) were measured on enhancement-versus-time curves, and pharmacokinetic parameters (hepatic extraction fraction [HEF] and mean residence time [MRT]) were obtained by means of deconvolution analysis of the concentration-versus-time curves in the liver and the portal vein. The parameters were correlated at simple and multiple regression analysis with the expression of the hepatic anion uptake transporter organic anion-transporting polypeptide 1A1 (Oatp1a1), the hepatobiliary transporter multidrug resistance–associated protein 2 (Mrp2), and the backflux transporter Mrp4, as determined with reverse transcription polymerase chain reaction.In rats with advanced liver fibrosis, the Emax, Tmax, HEF, and MRT decreased significantly relative to those in control rats, whereas the elimination half-life increased significantly. The enhancement and pharmacokinetic parameters correlated significantly with the expression of the transporters at simple regression analysis. At multiple regression analysis, HEF was the only parameter that was significantly associated with the expression of Oatp1a1 and Mrp2 (P < .001, r = 0.74 and P < .001, r = 0.70, respectively).The pharmacokinetic parameter HEF at dynamic gadoxetate-enhanced MR imaging is independently correlated with hepatic organic anion transporter expression.

To evaluate the value of diffusion-weighted imaging (DWI) in detecting residual tumours (RTs) in colorectal liver metastases (CLMs) following chemotherapy, with a focus on tumour periphery. From January 2009–January 2012, 57 patients who underwent liver resection for CLMs with preoperative MRI (

To assess the value of the liver and spleen viscoelastic parameters at multifrequency MR elastography to determine the degree of portal hypertension and presence of high-risk oesophageal varices in patients with cirrhosis.From January to September 2012, 36 consecutive patients with cirrhosis evaluated for transplantation were prospectively included. All patients underwent hepatic venous pressure gradient (HVPG) measurements and endoscopy to assess oesophageal varices. Multifrequency MR elastography was performed within the liver and spleen. The shear, storage and loss moduli were calculated and compared to the HVPG with Spearman coefficients and multiple regressions. Patients with and without severe portal hypertension and high-risk varices were compared with Mann-Whitney tests, logistic regression and ROC analysis.The liver storage and loss moduli and the spleen shear, storage and loss moduli correlated with the HVPG. At multiple regression, only the liver and the spleen loss modulus correlated with the HVPG (r = 0.44, p = 0.017, and r = 0.57, p = 0.002, respectively). The spleen loss modulus was the best parameter for identifying patients with severe portal hypertension (p = 0.019, AUROC = 0.81) or high-risk varices (p = 0.042, AUROC = 0.93).The spleen loss modulus appears to be the best parameter for identifying patients with severe portal hypertension or high-risk varices.1. Noninvasive HVPG assessment can be performed with liver and spleen MR elastography 2. The spleen loss modulus enables the detection of high-risk oesophageal varices 3. The spleen loss modulus enables the detection of severe portal hypertension.

To determine if diffusion-weighted (DW) magnetic resonance (MR) imaging with measurements of the apparent diffusion coefficient (ADC), pure diffusion coefficient, perfusion-related diffusion coefficient, and perfusion fraction can be used to differentiate between viable tumor and fibrous and necrotic regions within malignant liver tumors.The prospective study was approved by the institutional review board, and informed consent was obtained from all patients. Forty-eight patients with 51 malignant tumors were assessed. MR images of the liver were obtained by using DW imaging with 11 b factors (0-500 sec/mm(2)) and gadolinium-enhanced three-dimensional gradient-echo T1-weighted imaging. Tumors were segmented into viable tumor and fibrous and necrotic regions according to the enhancement pattern after injection of a nonspecific gadolinium chelate and, in surgically removed lesions, results of histopathologic correlation. The ADC, pure diffusion coefficient, perfusion-related diffusion coefficient, and perfusion fraction were calculated, and values were compared between viable tumor and fibrous and necrotic regions with the Kruskal-Wallis test followed by the Dunn multiple comparison test.The pure diffusion coefficient differed significantly between regions of viable tumor tissue and fibrosis (1.16 × 10(-3) mm(2)/sec ± 0.29 and 1.48 × 10(-3) mm(2)/sec ± 0.31, respectively; P = .016) and between regions of viable tumor tissue and necrosis (1.70 × 10(-3) mm(2)/sec ± 0.49, P = .002). There was a significantly lower perfusion fraction in necrotic regions (14% ± 6) than in viable tumor regions (21% ± 8, P = .005), but the perfusion fraction of the fibrous regions (21% ± 7) did not differ significantly from that of the other two regions. ADCs and perfusion-related diffusion coefficients did not differ significantly among the three regions.Results of this study show that viable tumor regions in malignant liver tumors can be differentiated from fibrous and necrotic regions with use of the pure diffusion coefficient but not with the other diffusion parameters.

To assess the value of the viscoelastic parameters in the characterisation of liver tumours at MR elastography.Ninety-four patients with liver tumours1 cm prospectively underwent MR elastography using 50-Hz mechanical waves and a full three-directional motion-sensitive sequence. The model-free viscoelastic parameters (the complex shear modulus and its real and imaginary parts, i.e. the storage and loss moduli) were calculated in 72 lesions after exclusion of cystic, treated or histopathologically undetermined tumours.We observed higher absolute shear modulus and loss modulus in malignant versus benign tumours (3.38 ± 0.26 versus 2.41 ± 0.15 kPa, P 0.01 and 2.25 ± 0.26 versus 1.05 ± 0.13 kPa, P 0.001, respectively). Moreover, the loss modulus of hepatocellular carcinomas was significantly higher than in benign hepatocellular tumours. The storage modulus did not differ significantly between malignant and benign tumours. The area under the receiver-operating characteristic curve of loss modulus was significantly larger than that of the absolute shear modulus and storage modulus when comparing malignant and benign lesions.The increased loss modulus is a better discriminator between benign and malignant tumours than the increased storage modulus or absolute value of the shear modulus.• Magnetic Resonance elastography is a new method of assessing the liver. • Increased loss modulus is an indicator of malignancy in hepatic tumours. • Loss modulus is a better discriminator than absolute shear modulus values. • The viscoelastic properties of lesions offer promise for characterising liver tumours.

There is a strong need to obtain precise surrogate biomarkers to improve the accuracy of diagnosis for gliomas, and to effectively evaluate therapeutic response. Often pre-clinical models of disease are used to develop diagnostic procedures and assess the effectiveness of a potential therapy. For gliomas, there are a variety of rodent models that have been investigated by numerous investigators over the past few decades, ranging from intracranial rodent glioma cell implantation models, intracranial human glioma xenografts, orthotopic implantation of human glioma stem cells, multipotent human glioblastoma stem-like neurosphere lines, transgenic mouse models, to viral-induced progenitor or stem cell derived glioma models. Tumor grades in these models vary from low to high grade tumors, with many of the high-grade glioma models sharing some of the characteristics of human grade IV glioblastoma multiforme (GBM). Many of the characteristic features of gliomas can be assessed diagnostically with in vivo imaging techniques such as magnetic resonance imaging (MRI). MRI has the capability of obtaining morphological/anatomical, functional, biophysical, molecular and metabolic information of a disease at various pathological stages of development. Tumor characteristics often associated with aggressive gliomas include an invasive growth pattern, angiogenesis, necrosis, hypoxia, edema, and alterations in major metabolic pathways. Morphological features, such as tumor size and position, infiltrative growth, hemorrhaging, necrotic lesions, edema, mass effect, heterogeneity, and cyst formation, can be followed using standard contrast-enhanced T1-weighted MR imaging or non-contrast T2-weighted imaging. Although conventional MRI provides us with some indication about the nature of the lesion or tumor, it has limited sensitivity and specificity in determining histological type and grade, delineating margins and differentiating edema, as well as effectively evaluating therapeutic effects or side-effects. Incorporating some advanced MR techniques, such as MR angiography (MRA), perfusion-weighted MR imaging (PWI), diffusion-weighted MR imaging (DWI), MR spectroscopy (MRS), and molecular MRI (mMRI), may help to overcome some of those limitations. Angiogenesis associated with major blood vessels can be assessed using MR angiography, whereas perfusion-weighted imaging can be used to monitor angiogenesis associated with capillary vessels in tumors. Biophysical parameters such as water diffusion, as measured by diffusion-weighted imaging, have also provided

Gliomas, the most common primary brain tumors in adults, have a poor outcome. PBN (α-phenyl- tert -butylnitrone) and OKN007 (2,4-disulfophenyl-PBN) are nitrones that have demonstrated beneficial effects in many aging diseases. In this study, we evaluated the anti-tumor effects of PBN and OKN007 in several rodent glioma models (C6, RG2, and GL261) by assessing metabolite alterations with magnetic resonance spectroscopy (MRS). PBN or OKN007 was administered in drinking water before or after tumor formation. MR imaging and single-voxel point-resolved spectroscopy were done to assess tumor morphology and metabolites, after therapy. Major metabolite ratios (choline, N -acetylaspartate, and lipid (methylene or methyl), all compared to creatine), as well as quantification of individual metabolite concentrations, were assessed. Nitrones induced tumor metabolism changes that resulted in restoring major metabolite ratios close to their normal levels, in the glioma regression phase. Nitrone treatment decreased the lipid (methylene)-to-creatine ratio, as well as the estimated concentration of lipid (methylene) significantly. Alterations in lipids can be a useful marker for the evaluation of the efficacy associated with treatment and were found in this study to be related to the reduction of necrosis, but not apoptosis. OKN007 was more effective than PBN when administered after tumor formation in the C6 glioma model. In conclusion, 1 H MRS and conventional MRI are useful methods to assess and follow the response of varied glioma models to anti-tumor treatments.

Purpose: To demonstrate that OKN007, a disulfonyl derivative of phenyl-tert-butyl nitrone (PBN), has anti-glioma activity in the clinically relevant C6 rat glioma model using multi-parametric magnetic resonance imaging. Materials and Methods: Twenty-one rats were intracerebrally implanted with C6 cells and administered OKN007 or kept as controls. Animals were monitored with MRI at 7 Tesla (T), using morphologic, diffusion-weighted and perfusion imaging, followed by histology and Western blots of angiogenesis and inflammatory markers. Results: OKN007 was found to decrease tumor volumes and increase survival. The glioma tissues of OKN007-treated rats were found to have longitudinal apparent diffusion coefficients (ADCz) of 0.76 ± 0.06 × 10−3 mm2/s, similar to the contralateral tissue and significantly smaller than untreated gliomas (0.97 ± 0.13 × 10−3 mm2/s). They had higher perfusion rates (66 ± 4 mL/100 g·min) than untreated gliomas (26 ± 7 mL/100 g·min). All examined molecular markers were decreased in OKN007-treated rat gliomas, compared with elevated levels in untreated rats. Conclusion: MRI assessment was successfully used to monitor a decrease in tumor growth, and corresponding alterations in ADC and perfusion rates in rat C6 gliomas treated with the anti-glioma agent, OKN007. J. Magn. Reson. Imaging 2010;31:796–806. ©2010 Wiley-Liss, Inc.

In tissue engineering it is often necessary to assess angiogenesis associated with engineered tissue grafts. The levels of vascular endothelial growth factor receptor 2 (VEGF-R2) is elevated during angiogenesis. The goal of this study was to develop and assess a novel magnetic resonance imaging (MRI) molecular probe for the in vivo detection of VEGF-R2 in an experimental rodent model of disease. The possible use of the probe in tissue engineering applications is discussed. The molecular targeting agent we used in our study incorporated a magnetite-based dextran-coated nanoparticle backbone covalently bound to an anti-VEGF-R2 antibody. We used molecular MRI with an anti-VEGF-R2 probe to detect in vivo VEGF-R2 levels as a molecular marker for gliomas (primary brain tumors). Tumor regions were compared with normal tissue. Nonimmune nonspecific normal rat immunoglobulin G coupled to the dextran-coated nanoparticles was used as a control. Prussian blue staining for iron-based nanoprobes was used to confirm the specificity of the probe for VEGF-R2 in glioma tissue. VEGF-R2 levels in tumor tissues were also confirmed in western blots and via immunohistochemistry. Based on our results, in vivo evaluation of tissue angiogenesis using molecular MRI is possible in tissue engineering applications.

Results: All animals exhibited a more painful joint on day 3 postinjection compared to day 0 (Fig. 1). Higher MIA dose caused more pain and greater gait alteration than the lower dose after day 7 with one exception. There was no difference on weight distribution between the two doses on day 35. Animals injected with 2mg MIA had larger knee diameter than those with 0.5mg MIA. Bone volume (Fig. 2) was significantly lower in animals injected with high dose of MIA. However, bone volume in both groups increased from day 21 to day 35 regardless of MIA dose. The high MIA dose caused significantly more severe cartilage matrix damage (Fig. 3), bone resorption and osteophyte formation on day 21, which did not worsen further by day 35. In the low MIA injection group, severity of joint damage increased from day 21 to day 35, resulting in similar levels of damage for both groups by day 35. The subchondral bone sclerosis was worse in lower dose group than the higher one on both days. Conclusions: In this study, we evaluated the temporal effect of MIA dose on joint pain and structural damages using an established rat model. The results demonstrated that the higher MIA dose caused more severe joint swelling, pain, and histopathologic alterations than the lower dose. It was observed that both standing and moving pain recovered over time for both groups over 35 days while the joint structures continued their deterioration. Most surprisingly, the standing pain was almost completely alleviated by day 35 while the joints exhibited a strikingly severe degeneration. To our knowledge, this is the first report of such temporally differential changes on pain and structural damage in MIA induced rodent model. The results will shed light on the application of rat MIA model in evaluating biologics and pharmaceuticals for OA treatment.

Gliomas are the most common and lethal primary brain tumors in the adult, with a median survival time of 12 to 15 months for grade IV gliomas, glioblastoma multiforme. PBN and OKN007 are nitrones which have demonstrated beneficial effects in many aging diseases. In this study, we evaluated the anti-tumor effects of PBN or OKN007 in several rodent glioma models (C6, RG2, and GL261) by assessing metabolite alterations with magnetic resonance spectroscopy (MRS). PBN or OKN007 was administered in drinking water prior to or post tumor formation. MRI and short echo time, single-voxel point-resolved spectroscopy (PRESS) were obtained to assess tumor morphology and metabolites, respectively, following therapy. Major metabolite ratios (Choline, N-acetyl aspartate (NAA), Lipid (methylene), and Lipid (methyl), all compared to Creatine) were assessed. Nitrones induced tumor metabolism changes that resulted in restoring major metabolite ratios close to their normal levels, in the glioma regression phase. Nitrones treatment decreased the Lipid (methylene) to Creatine ratio significantly, which can be a useful marker for evaluation of the efficacy of the treatments, and was found to be related with the reduction of necrosis. OKN007 was more effective than PBN when administered post-tumor formation in the C6 glioma model. OKN007 was able to inhibit angiogenic factors (VEGF, bFGF and HGF) and induce apoptosis (indicated by an increase of the apoptotic marker m30) in C6 gliomas, which might be potential mechanisms that are involved in the anti-glioma effects. In conclusion, OKN007 and PBN are effective in inhibiting the growth of several experimental gliomas and may be considered as potential therapeutics for a clinical trial in human gliomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 675. doi:10.1158/1538-7445.AM2011-675

The nitrone compound OKN007, a disulfonated derivative of phenyl-tert-butylnitrone, is known to have anti-glioma properties in a rat C6 glioma model. In this study, the effect of OKN007 was studied using three orthotopically implanted glioma cell lines in the rat. In addition, some preliminary data investigating the involvement of the iNOS anti-inflammatory pathway in the anti-glioma activity of OKN007 is provided. The effect OKN007 on glioma was assessed by magnetic resonance imaging of rats orthotopically implanted with 10^6 C6, F98 or RG2 cells. Tumor volumes and growth rates were determined with T2-weighted imaging. The inflammatory edema and other properties of the glioma were assessed with diffusion-weighted imaging. Finally, tumor perfusion rates were measured by arterial spin labeling. The drug (25-30μmol/(kg·day)) was administered 15 days after tumor cell implantation in the drinking water or by a continuous intravenous perfusion, with appropriate saline controls. The expression levels of iNOS were measured using western blots. In addition, C6 cells stably transfected with an iNOS shRNA silencing plasmid were also implanted in an effort to delineate the involvement of this mediator in tumor growth. OKN007 was found to have an effect on the growth of C6 gliomas both when administered in the drinking water or intravenously. Doubling times were slower when OKN007 was administered orally (7.9±1.2 days, versus 2.7±0.3 days for the controls), but not when administered intravenously, although the latter route was tested on a smaller cohort. The drug affected the perfusion and diffusion profiles of the C6 tumors for both types of administration. In the C6 model, administration of the drug brought perfusion and diffusion values closer to those found in normal brain. Both administration routes had an effect on the tumor volume at day 35. In the RG2 model, OKN007 increased the doubling times of the tumors, although more controls are required to reach statistical significance. The effects of OKN007 on the F98 glioma cell line are currently under investigation. Western blot analyses on the C6 model revealed that in treated animals the iNOS levels, although higher than in the normal brain, were lower than in non treated tumors. Finally, preliminary evidence of the requirement of iNOS for tumor development in the context of orthotopic implantation of the tumor cells was obtained using the iNOS shRNA-transfected C6 cell line. In conclusion, OKN007 was found to have a suppressive effect on the growth of C6 rat glioma, with drinking water administration yielding the best results. The nitrone may also have a therapeutic potential for RG2 and F98 models. The precise mechanisms of action of OKN007 are still unknown, but may involve an interference with iNOS-mediated inflammation. Together with the established safety of this nitrone for humans, our results indicate that OKN007 may be a promising anti glioma agent for clinical use. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3574.