Relative Signal Intensity Research Articles

Morphological and functional changes in pituitary-thyroid axis following prolonged exposure of female rats to constant light.

Light regulates numerous physiological functions and synchronizes them with the environment, in part by adjusting secretion of different hormones. We hypothesized that constant light (CL) would disturb pituitary-thyroid axis. Our aim was to determine morphological and functional changes in this endocrine system in such extreme conditions and, based on the obtained results, to propose the underlying mechanism(s). Starting from the thirtieth postnatal day, female Wistar rats were exposed to CL (600 lx) for the following 95 days. The controls were maintained under the regular laboratory lighting conditions. After decapitation, pituitaries and thyroids were prepared for further histomorphometric, immunohistochemical, and immunofluorescence examinations. Concentration of thyroid stimulating hormone (TSH), total T4 and T3 (TH) were determined. Thyroid tissue of light-treated rats was characterized by microfollicular structure. We detected no change in total thyroid volume, localization and accumulation of thyroglobulin, thyroid peroxidase, and sodium-iodide symporter in the follicular epithelium of CL rats. The volume of follicular epithelium and activation index were increased, while volume of the colloid and serum levels of TH decreased. In the pituitary, the relative intensity of TSH β-immunofluorescence signal within the cytoplasm of thyrotrophs increased, but their average cell volume and the relative volume density decreased. Serum TSH was unaltered. We conclude that exposure of female rats to CL induced alterations in pituitary-thyroid axis. Thyroid tissue was characterized by microfollicular structure. Serum TH levels were reduced without accompanying increase in serum TSH. We hypothesize that increased secretion and clearance of TH together with unchanged or even decreased hormonal synthesis, resulted in decreased serum TH levels in CL group. We assume this decrease consequently led to increased synthesis and/or accumulation of pituitary TSH. However, decreased average TSH cell volume and relative volume density, together with unchanged serum TSH, point to additional, negative regulation of thyrotrophs.

Diagnostic accuracy of dual-echo (in- and opposed-phase) T1-weighted gradient recalled echo for detection and grading of hepatic iron using quantitative and visual assessment.

Detection and quantification of hepatic iron with dual-echo gradient recalled echo (GRE) has been proposed as a rapid alternative to other magnetic resonance imaging (MRI) techniques. Co-existing steatosis and T1 weighting are limitations. This study assesses the accuracy of routine dual-echo GRE. Between 2010 and 2013, 109 consecutive patients underwent multi-echo (ME) MRI and dual-echo GRE for quantification of hepatic iron. Liver iron concentration (LIC) was calculated from ME-MRI. Relative signal intensity (RSI) and fat signal fraction (FSF) were calculated from dual-echo GRE. Four radiologists subjectively evaluated dual-echo GRE (±subtraction). Diagnostic accuracy was compared between techniques and correlated with biopsy using Fisher's exact test, Spearman correlation and regression. The sensitivity of visual detection of iron ranged from 48 to 55%. Subtraction did not increase sensitivity (p < 0.001). Inter-observer variability was substantial (κ = 0.72). The specificity of visual detection of iron approached 100% with false-positive diagnoses observed using subtraction. LIC showed a higher correlation with histopathological iron grade (r = 0.94, p < 0.001) compared with RSI (r = 0.65, p = 0.02). Univariate regression showed an association between RSI and LIC (B = 0.98, p < 0.001, CI 0.73-1.23); however, the association was not significant with multi-variate regression including FSF (p = 0.28). Dual-echo GRE has low sensitivity for hepatic iron. Subtraction imaging can result in false-positive diagnoses. • Routine liver MRI studies cannot effectively screen patients for iron overload. • Concomitant hepatic steatosis and iron limits diagnostic accuracy of routine liver MRI. • Dual-echo GRE subtraction imaging causes false-positive diagnoses of iron overload. • Dedicated MRI techniques should be used to diagnose and quantify iron overload.

Clinical significance of an increased cochlear 3D fluid-attenuated inversion recovery signal intensity on an MR imaging examination in patients with acoustic neuroma.

The increased cochlear signal on FLAIR images in patients with acoustic neuroma is explained by an increased concentration of protein in the perilymphatic space. However, there is still debate whether there is a correlation between the increased cochlear FLAIR signal and the degree of hearing disturbance in patients with acoustic neuroma. Our aim was to investigate the clinical significance of an increased cochlear 3D FLAIR signal in patients with acoustic neuroma according to acoustic neuroma extent in a large patient cohort. This retrospective study enrolled 102 patients with acoustic neuroma, who were divided into 2 groups based on tumor location; 22 tumors were confined to the internal auditory canal and 80 extended to the cerebellopontine angle cistern. Pure tone audiometry results and hearing symptoms were obtained from medical records. The relative signal intensity of the entire cochlea to the corresponding brain stem was calculated by placing regions of interest on 3D FLAIR images. Statistical analysis was performed to compare the cochlear relative signal intensity between the internal auditory canal acoustic neuroma and the cerebellopontine angle acoustic neuroma. The correlation between the cochlear relative signal intensity and the presence of hearing symptoms or the pure tone audiometry results was investigated. The internal auditory canal acoustic neuroma cochlea had a significantly lower relative signal intensity than the cerebellopontine angle acoustic neuroma cochlea (0.42±0.15 versus 0.60±0.17, P<.001). The relative signal intensity correlated with the audiometric findings in patients with internal auditory canal acoustic neuroma (r=0.471, P=.027) but not in patients with cerebellopontine angle acoustic neuroma (P=.427). Neither internal auditory canal acoustic neuroma nor cerebellopontine angle acoustic neuroma showed significant relative signal intensity differences, regardless of the presence of hearing symptoms (P>.5). The cochlear signal on FLAIR images may be an additional parameter to use when monitoring the degree of functional impairment during follow-up of patients with small acoustic neuromas confined to the internal auditory canals.

Thiol-PEG-carboxyl-stabilized Fe2O3/Au nanoparticles targeted to CD105: Synthesis, characterization and application in MR imaging of tumor angiogenesis

ObjectiveTo detect tumor angiogenesis in tumor-bearing mice using thiol-PEG-carboxyl-stabilized Fe2O3/Au nanoparticles targeted to CD105 on magnetic resonance imaging (MRI). MethodsFe2O3/Au nanoparticles (hybrids) were prepared by reducing Au3+ on the surface of Fe2O3 nanoparticles. Hybrids were stabilized with thiol-PEG-carboxyl via the Au–S covalent bond, and further conjugated with anti-CD105 antibodies through amide linkages. Characteristics of the hybrid-PEG-CD105 nanoparticles were evaluated. Using these nanoparticles, the labeling specificity of human umbilical vein endothelial cells (HUVECs) was evaluated in vitro. MRI T2*-weighted images were obtained at different time points after intravenous administration of the hybrid-PEG-CD105 nanoparticles in the tumor-bearing mice. After MR imaging, the breast cancer xenografts were immediately resected for immunohistochemistry staining and Prussian blue staining to measure the tumor microvessel density (MVD) and evaluate the labeling of blood microvessels by the hybrid-PEG-CD105 nanoparticles in vivo. ResultsThe mean diameter of the hybrid-PEG-CD105 nanoparticles was 56.6±8.0nm, as measured by transmission electron microscopy (TEM). Immune activity of the hybrid-PEG-CD105 nanoparticles was 53% of that of the anti-CD105 antibody, as detected by enzyme-linked immunosorbent assay (ELISA). The specific binding of HUVECs with the hybrid-PEG-CD105 nanoparticles was proved by immunostaining and Prussian blue staining in vitro. For breast cancer xenografts, the combination of the hybrid-PEG-CD105 nanoparticles with blood microvessels was detectable by MRI after 60min administration of the contrast agent. The T2* relative signal intensity (SIR) was positively correlated with the tumor MVD (R2=0.8972). ConclusionAnti-CD105 antibody-coupled, thiol-PEG-carboxyl-stabilized core–shell Fe2O3/Au nanoparticles can efficiently target CD105 expressed by HUVECs. Furthermore, the hybrid-PEG-CD105 nanoparticles can be used to detect tumor angiogenesis in vivo.

Neuronal transport defects of the MAP6 KO mouse – a model of schizophrenia – and alleviation by Epothilone D treatment, as observed using MEMRI

The MAP6 (microtubule-associated protein 6) KO mouse is a microtubule-deficient model of schizophrenia that exhibits severe behavioral disorders that are associated with synaptic plasticity anomalies. These defects are alleviated not only by neuroleptics, which are the gold standard molecules for the treatment of schizophrenia, but also by Epothilone D (Epo D), which is a microtubule-stabilizing molecule. To compare the neuronal transport between MAP6 KO and wild-type mice and to measure the effect of Epo D treatment on neuronal transport in KO mice, MnCl2 was injected in the primary somatosensory cortex. Then, using manganese-enhanced magnetic resonance imaging (MEMRI), we followed the propagation of Mn2+ through axonal tracts and brain regions that are connected to the somatosensory cortex. In MAP6 KO mice, the measure of the MRI relative signal intensity over 24h revealed that the Mn2+ transport rate was affected with a stronger effect on long-range and polysynaptic connections than in short-range and monosynaptic tracts. The chronic treatment of MAP6 KO mice with Epo D strongly increased Mn2+ propagation within both mono- and polysynaptic connections. Our results clearly indicate an in vivo deficit in neuronal Mn2+ transport in KO MAP6 mice, which might be due to both axonal transport defects and synaptic transmission impairments. Epo D treatment alleviated the axonal transport defects, and this improvement most likely contributes to the positive effect of Epo D on behavioral defects in KO MAP6 mice.

DWI Intensity Values Predict FLAIR Lesions in Acute Ischemic Stroke

Background and PurposeIn acute stroke, the DWI-FLAIR mismatch allows for the allocation of patients to the thrombolysis window (<4.5 hours). FLAIR-lesions, however, may be challenging to assess. In comparison, DWI may be a useful bio-marker owing to high lesion contrast. We investigated the performance of a relative DWI signal intensity (rSI) threshold to predict the presence of FLAIR-lesions in acute stroke and analyzed its association with time-from-stroke-onset.MethodsIn a retrospective, dual-center MR-imaging study we included patients with acute stroke and time-from-stroke-onset ≤12 hours (group A: n = 49, 1.5T; group B: n = 48, 3T). DW- and FLAIR-images were coregistered. The largest lesion extent in DWI defined the slice for further analysis. FLAIR-lesions were identified by 3 raters, delineated as regions-of-interest (ROIs) and copied on the DW-images. Circular ROIs were placed within the DWI-lesion and labeled according to the FLAIR-pattern (FLAIR+ or FLAIR−). ROI-values were normalized to the unaffected hemisphere. Adjusted and nonadjusted receiver-operating-characteristics (ROC) curve analysis on patient level was performed to analyze the ability of a DWI- and ADC-rSI threshold to predict the presence of FLAIR-lesions. Spearman correlation and adjusted linear regression analysis was performed to assess the relationship between DWI-intensity and time-from-stroke-onset.ResultsDWI-rSI performed well in predicting lesions in FLAIR-imaging (mean area under the curve (AUC): group A: 0.84; group B: 0.85). An optimal mean DWI-rSI threshold was identified (A: 162%; B: 161%). ADC-maps performed worse (mean AUC: A: 0.58; B: 0.77). Adjusted regression models confirmed the superior performance of DWI-rSI. Correlation coefficents and linear regression showed a good association with time-from-stroke-onset for DWI-rSI, but not for ADC-rSI.ConclusionAn easily assessable DWI-rSI threshold identifies the presence of lesions in FLAIR-imaging with good accuracy and is associated with time-from-stroke-onset in acute stroke. This finding underlines the potential of a DWI-rSI threshold as a marker of lesion age.

Difficulty of MRI based identification of lesion age by acute infra-tentorial ischemic stroke.

BackgroundSystemic thrombolysis in acute ischemic stroke is restricted to the 4.5 h time window. Many patients are excluded from this treatment because symptom onset is unknown. Magnetic resonance imaging (MRI) studies have shown that stroke patients presenting with acute supra-tentorial diffusion-weighted imaging (DWI) lesions that do not have matching lesions on fluid attenuated inversion recovery (FLAIR) are likely to be within a 4.5 hour time window. This study examines the DWI-FLAIR mismatch in infra-tentorial stroke.MethodsThis was a retrospectively conducted substudy of the “1000+” study; a prospective, single-center observational study (http://clinicaltrials.gov; NCT00715533). Fifty-six patients with infra-tentorial stroke confirmed by MRI and known symptom onset who underwent the scan within 24 h after symptom onset were analysed. Two neurologists blinded to clinical information separately rated the DWI lesion visibility on FLAIR. Lesion volume, relative signal intensities of DWI and relative apparent diffusion coefficient values were determined.ResultsRegarding baseline characteristics our study population had a median age of 66 years, a median time from symptom onset to MRI of 616.5 minutes, a median NIHSS of 3 and a median DWI lesion volume of 0.26 ml. A negative FLAIR allocated patients to a time window under 4.5 h correctly with a sensitivity of 55% and a specificity of 61%, a positive predictive value of 44% and a negative predictive value of 71%. FLAIR positivity decreased with age (p = 0.018), and showed no significant correlation to lesion volume (p = 0.145).ConclusionsIn our study the DWI-FLAIR-Mismatch does not help to reliably identify patients within 4.5 h of symptom onset in acute ischemic infra-tentorial stroke. Thus therapeutical decisions based on the DWI-FLAIR mismatch estimation of time from onset cannot be recommended in patients with infra-tentorial stroke.

Gene expression profiling of porcine cells and tissues by microarray analysis

Pig to human xenotransplantation represents an ambitious venture that requires, besides evasion of rejection mechanisms and physiological incompatibilities, the generation of pathogen‐free pigs as donors for well characterized xenografts to warrant medicinal products that do comply with statutory regulatory demands [1–3]. The publication of a high quality draft sequence for the pig genome (Sus scrofa) and a series of accompanying reports for the first time offered the feasibility of whole genome expression profiling of porcine tissues and cells [4–8].The SFB TR CRC 127 project Z2 “Microbiological Safety including Virological Safety” is based on microbial profile analysis of porcine tissues in order to prevent zoonotic events, including infection by porcine endogenous retroviruses (PERV) [9]. The project comprises the detection and characterization of potential pathogens as well as the investigation of the microbial influence on the transcriptional status of tissues and cells. Hence, specific expression patterns, e.g. up‐regulation of antiviral host factors or cell cycle/apoptotic regulators, may also provide information on ongoing or precedent events that may have impact on tissues/cells quality and therefore its suitability as xenografts.We use microarray technology for monitoring viability of tissues and cells as well as their microbial/viral status. An Agilent based, 60K DNA microarray representing 25,415 different genes of the recently published Sus scrofa genome (NCBI Sus scrofa 10.2‐assembly) was generated [10]. The microarray was specified for German Landrace and Göttingen Minipig, amongst other pig species, by hybridizing complex RNA samples generated from five different pig organs and blood as well as chromosomal porcine DNA to highlight non expressed genes. Four Diagnostic PERV sequences for pro/pol (all classes of PERV), env (to differentiate between PERV‐A, ‐B and ‐C) as well as 15 human transgenes such as CD59 (human complement regulatory protein), DAF (Decay accelerating factor or CD55), human A20 (hA20) and others were included. In total, the microarray displays 25,434 genes each represented by up to three different 60‐mer oligonucleotides.To reveal functionality of the microarray the transcriptional status of ST‐IOWA cells freshly infected with molecularly cloned virus PERV‐C (1312) [11] was monitored. Total mRNA levels at day 7, 28 and 56 post infection were compared with naive uninfected cells. All samples were tested in triplicates and the relative signal intensity of hybridized probes was compared. Special attention was given to antiviral host factors such as APOBEC and tetherin of which involvement as antiviral factors on PERV expression has been demonstrated [12–14]. Constitutively expressed housekeeping genes, i.e. porcine glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), beta actin and cyclophilin A, respectively, were used as controls [15, 16].The presented microarray supports the safety and quality by monitoring the transcriptional status of xenotransplants.

Delayed hepatic signal recovery on ferucarbotran-enhanced magnetic resonance images in a rat model with regional liver irradiation

To determine whether superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging could demonstrate signal recovery delay in irradiated areas of rat livers. We also investigated the relationship between MR imaging and histological findings. Twelve rats received 20μmol iron/kg of SPIO followed by X-irradiation to the right upper abdomen 4h later. Radiation doses were 0, 50 and 70Gy. Hepatic signals were assessed on unenhanced T 2 (*) -weighted images for up to 7days using a 9.4-Tesla scanner. The livers were excised on day 7 and examined histologically. Normalized relative signal intensity of 70Gy-irradiated right liver lobe (2.36±0.22) and 50Gy-irradiated right liver lobe (2.37±0.46) was significantly lower than that of the non-irradiated right liver lobe (4.04±0.28) on day 7, respectively (p<0.05). Pearson product-moment correlation coefficient between relative intensity of the liver and the number of hepatic iron deposits was -0.588 (p<0.01). Superparamagnetic iron oxide-enhanced MR imaging could demonstrate signal recovery delay in irradiated areas of rat livers. It seems that the signal recovery delay in irradiated areas was due to SPIO-derived iron deposition. Hepatic signal recovery could be a novel diagnostic marker for delineation of irradiated areas.

Visual and Region of Interest–Based Inter-Rater Agreement in the Assessment of the Diffusion-Weighted Imaging– Fluid-Attenuated Inversion Recovery Mismatch

WAKE-UP is a randomized, placebo-controlled MRI-based trial of thrombolysis in wake-up stroke using the mismatch between a lesion's visibility in diffusion-weighted imaging and fluid-attenuated inversion recovery (FLAIR) sequences as its main imaging inclusion criterion. Visual judgment of lesion conspicuity on FLAIR is however methodically limited by moderate inter-rater agreement. We therefore sought to improve rating homogeneity by incorporating quantitative signal intensity measurements. One hundred forty-three data sets of patients with acute ischemic stroke were visually rated by 8 raters with respect to WAKE-UP study inclusion and exclusion criteria, and inter-rater agreement was calculated. A subanalysis was performed on 45 cases to determine a threshold value of relative signal intensity (rSI) between the ischemic lesion and contralateral healthy tissue which best corresponded to a visually established verdict of FLAIR positivity. The usefulness of this threshold in improving inter-rater agreement was evaluated in an additional sample of 50 patients. Inter-rater agreement for inclusion into the WAKE-UP trial was 73% with a free-marginal κ of 0.46. A threshold of rSI which best correlated with the visual rating of lesions as FLAIR positive was 1.20. The addition of rSI measurements to visual evaluation did not change the inter-rater agreement. Introducing a semiquantitative measure for FLAIR rSI did not improve the agreement between individual raters. However, enhancing visual assessment with rSI measurements can provide reassurance to local investigators in cases of uncertainty.

Rapid analysis of Δ‐9‐tetrahydrocannabinol in hair using direct analysis in real time ambient ionization orbitrap mass spectrometry

Forensic hair analysis methods are laborious, time-consuming and provide only a rough retrospective estimate of the time of drug intake. Recently, hair imaging methods using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported, but these methods require the application of MALDI matrix and are performed under vacuum. Direct analysis of entire locks of hair without any sample pretreatment and with improved spatial resolution would thus address a need. Hair samples were attached to stainless steel mesh screens and scanned in the X-direction using direct analysis in real time (DART) ambient ionization orbitrap MS. The DART gas temperature and the accuracy of the probed hair zone were optimized using Δ-9-tetrahydrocannabinol (THC) as a model compound. Since external contamination is a major issue in forensic hair analysis, sub-samples were measured before and after dichloromethane decontamination. The relative intensity of the THC signal in spiked blank hair versus that of quinine as the internal standard showed good reproducibility (26% RSD) and linearity of the method (R(2) = 0.991). With the DART hair scan THC could be detected in hair samples from different chronic cannabis users. The presence of THC was confirmed by quantitative liquid chromatography/tandem mass spectrometry. Zones with different THC content could be clearly distinguished, indicating that the method might be used for retrospective timeline assessments. Detection of THC in decontaminated drug user hair showed that the DART hair scan not only probes THC on the surface of hair, but penetrates deeply enough to measure incorporated THC. A new approach in forensic hair analysis has been developed by probing complete locks of hair using DART-MS. Longitudinal scanning enables detection of incorporated compounds and can be used as pre-screening for THC without sample preparation. The method could also be adjusted for the analysis of other drugs of abuse.

Comparative study of the relative signal intensity on DWI, FLAIR, and T2 images in identifying the onset time of stroke in an embolic canine model

In acute stroke magnetic resonance imaging, many attempts have been made to identify the onset time of ischemic events using the simply quantitative judgment of relative signal intensity (rSI) from various MR images. However, no uniform opinion has been achieved broadly till now. The controversy might derive from the potential patients' selection bias of clinical retrospective study, the discrepant MR parameters, and the various sample sizes among different studies. Thus, we evaluated the temporal change of the relative DWI signal intensity (rDWI), relative ADC value (rADC), relative FLAIR signal intensity (rFLAIR), and relative T2 signal intensity (rT2), and further compare their diagnostic value in identifying the hyperacute lesions based on our embolic canine model with clear onset time. Twenty ischemic models were successfully established. All rSI values were linearly correlated to time with significance until 24 h after model establishment (P < 0.05). Paired comparison of ROC curves showed that significant difference was found between rADC and other three rSIs (P < 0.0001). However, no significant difference was found among rDWI, rT2 and rFLAIR. Our results indicated that rDWI, rFLAIR and rT2 may be helpful to predict the onset time of ischemic events with the similar diagnostic value. However, the rADC does not have comparable predictive value in our embolic canine model.

Abstract T MP32: T1-Weighted Magnetic Resonance Imaging Evaluation of Carotid Artery Outward Remodeling in Carotid Endarterectomy and Stenting

Objective: We evaluated carotid artery outward remodeling and plaque relative signal intensity (rSI) in patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS) by T1-weighted Magnetic Resonance Imaging (T1-MRI), in order to define their clinical significance in carotid revascularization. Methods: Eighty-eight lesions (51 CEA and 37 CAS; symptomatic at 54.9 and 45.7%, respectively) from 93 patients who underwent carotid revascularization at our institute were retrospectively considered. We evaluated the carotid artery remodeling parameter of luminal stenosis, which is determined by a ratio of external cross-sectional vessel area (CSVA) at maximum stenosis, and reference CSVA at the distal portion of the ICA (carotid remodeling index, CRI), and MR intensities of atherosclerotic plaque (rSI) using T1 MRI (magnetization-prepared rapid acquisition with gradient-echo [MPRAGE]), preoperatively. We divided carotid lesions into 4 groups using median CRI and rSI: L/L (CRI &lt; 1.8, rSI &lt; 2.5), L/H (CRI &lt; 1.8, rSI ≥ 2.5), H/L (CRI ≥ , and rSI &lt; 2.5), and H/H (CRI ≥ 1.8, rSI ≥ 2.5). The endpoint was defined as the detection of acute ipsilateral ischemia on diffusion-weighted imaging (DWI) within 72 h of treatment. Results: A significant correlation was found between CRI and rSI (r = 0.359, p = 0.0006). Mean CRI and rSI were significantly higher in lesions treated with CEA than with CAS. Small abnormalities were observed on DWI in 4 cases (7.8%) in CEA, and 10 (27.0%) in CAS (p = 0.01). In the CAS group, the observed frequency of DWI abnormalities in group L/L, L/H, H/L, H/H were 5.5%, 40.0%, 40.0%, and 55.5%, respectively (p = 0.03). In multivariate analysis, rate of stenosis (Odds Ratio [OR]: 1.19; 95% confidence interval [CI]: 1.04-1.48; p = 0.0082), and non-L/L lesions (OR: 29.65; 95% CI: 2.97-555.12; p = 0.002) were independent risk factors for cerebral embolism. In the CEA group, no significant relationship was observed between plaque parameters and DWI lesions. Conclusion: CRI and rSI are complementary parameters to predict a high-risk plaque for CAS, but not for CEA. Preoperative evaluation with T1 MRI is useful to make decisions about treatment strategy for carotid artery stenosis.

Early Time Course of FLAIR Signal Intensity Differs between Acute Ischemic Stroke Patients with and without Hyperintense Acute Reperfusion Marker

Background: In animal models of stroke, the time course of blood-brain barrier (BBB) disruptions has been elaborately studied. In human patients, leakage of gadolinium into cerebrospinal fluid (CSF) space, visualized on MRI fluid attenuated inversion recovery (FLAIR) images, is considered a sign of BBB disruptions. It was termed ‘hyperintense acute reperfusion marker' (HARM) and was associated with hemorrhages. However, the time course of the leakage is unknown and difficult to study in human patients. Also, the association of HARM with signal intensities and enhancement in the parenchyma on FLAIR images has not been thoroughly researched. Methods: We analyzed imaging data of acute ischemic stroke patients who underwent repetitive MRI examinations within the first 36 h after the time of symptom onset. HARM was evaluated on FLAIR images. Regions of interest (ROI) of the hyperintensities on diffusion-weighted imaging (DWI) were determined for each time point and mirrored to the contralateral side. The ROI were furthermore corrected for CSF-filled space, using apparent diffusion coefficient (ADC) images. The corrected ROI were used to determine mean signal intensities of the lesions relative to the contralateral side on FLAIR, ADC and B₀ images for each time point. Results: The 18 included patients (5 females; median age: 69 years; median NIHSS score: 5) received 3-5 MRI examinations on the first day and 1-2 examinations on day 2 after stroke. Eight of the patients (44.4%) showed HARM on at least 1 examination. In 6 of these patients, HARM was already seen at the second examination, at the earliest 3.5 h after symptom onset. The HARM-positive patients had higher relative signal intensities (rSI) on FLAIR images in the parenchyma corresponding to the DWI-positive tissue compared with the HARM-negative patients. This difference between groups was statistically significant for the 2nd and 3rd examination (medians of 4.31 and 6.37 h from symptom onset, p < 0.001 and p = 0.005, respectively). No significant difference in rSI between groups was seen for ADC or B₀ images. Conclusion: HARM does not only represent a contrast medium leakage from the pial system into the CSF space. It is accompanied by a markedly increased rSI in the early ischemic lesion on FLAIR images, which is likely due to parenchymal enhancement. The lack of differences on B₀ images excludes a pure T2 effect.

Identification of hyperacute ischemic stroke with a more homogenous nature

AbstractPrevious reports revealed that middle cerebral artery occlusion (MCAO) models in rats were very diverse in nature, and experimental stroke of a more homogenous nature had not been previously documented. This paper aims to present our novel observations of experimental stroke in rats with similar MRI characteristics after MCAO. Immediately after MCAO, 19 rats were placed into a 4.7 T MRI scanner, and diffusion weighted imaging (DWI) of axial and coronal planes was repeated every 10 minutes up to post-occlusion 115 minutes. Apparent diffusion coefficient (ADC) values of the ischemic lesions were calculated and compared to those of the unaffected contra-lateral hemispheres. Successful MCAO was defined when the whole left MCA territory showed ADC abnormality on DWI. Percentage of hemispheric lesion volume (% HLV), relative ADC value (rADC), and relative DWI signal intensity (rDWI) were serially evaluated for quantitative analysis of ADC-derived lesion characteristics. Successful MCA territorial infarction was induced in nine rats (9/19, 47.4%). In quantitative analysis of ADC-derived lesion characteristics, lesion volumes of seven rats (group 1) were very similar, but larger than those of the other two rats (group 2): % HLV of initial MRI = 45.4 ± 2.5 / 19.1 ± 6.6. rADCs and rDWIs of group 1 showed similar patterns of temporal change, which was different from those of group 2. Using prospective diffusion MRI after MCAO in rats, we identified territorial hyperacute ischemic lesions with similar MRI characteristics. This observation would contribute to the establishment of more homogenous rodent models for ischemic stroke translational research.

In situ diagnostics of the SiC nanostructures growth process

Combustion synthesis (SHS, self-sustainable high-temperature synthesis), carried out in a modified calorimetric bomb, is a fast, efficient, self-sustainable, and one-step production method of new nanomaterials. Among them, SiC nanowires and their bundles are one of the most interesting due to their properties and a variety of possible applications. However, as the growth process occurs probably partially under non-equilibrium conditions, its control and monitoring are rather difficult. Furthermore, the synthesis is very sensitive to any change of process variables, so that the growth mechanism knowledge is essential for the optimization of the synthesis. To overcome those drawbacks, the in-situ diagnostics of combustion is proposed. It is based on the photo-registration of an optical signal (light emitted and observed via polycarbonate observation port). From full HD 25frames/s with resolution 1920×1080, one may calculate the relative signal intensity, its time evolution and find the reaction fingerprint. The validation of experimental protocol consisted in confirmation of results reproducibility, crucial in case of the nonlinear process, within different calculation algorithms and registration conditions.

Abstract 18596: Regional Assessment of Lower Extremity Tissue Oxygenation in Athletes Using Blood Oxygen Level-Dependent Magnetic Resonance Imaging

Background: Blood oxygen level-dependent (BOLD) MRI allows for evaluation of hemoglobin oxygenation within skeletal muscle, providing a non-invasive index of microvascular function. This study evaluated differences in relative signal intensity of BOLD MRI among lower extremity muscle groups during transient ischemia and reactive hyperemia in college football athletes, while also comparing strength and functional exercise results. Methods: BOLD MRI was performed on the lower leg of 19 males (19.8 ± 1.0 yrs) with a 3T magnet to evaluate regional changes in signal intensity among individual muscle groups during ischemia and reactive hyperemia induced by proximal cuff occlusion. Athletes were separated by position (larger linemen vs. smaller position players) for comparison purposes. The peak hyperemic value (PHV), or the maximum percent change in BOLD signal intensity from baseline, was assessed for each muscle group. Athletes’ lower body strength and jumping ability were evaluated and compared to BOLD responses. Results: Linemen presented with higher body fat and systolic blood pressure (p&lt;0.05). Athletes did not differ in maximal lower body strength; however, position players had greater vertical and broad jump performance (p&lt;0.0001). In analysis of all athletes, the soleus muscle, a slow twitch muscle generally with high capillary density, exhibited the largest PHV. The PHVs of gastrocnemius muscles for position players were significantly higher than linemen (p=0.03) and were associated with greater jumping performance. No differences were observed in other muscle groups when comparing position players and linemen. Conclusions: BOLD MRI offers a non-invasive technique for quantifying regional differences in lower extremity tissue oxygenation in the evaluation of microvascular function in relation to functional performance. Evaluation of changes in BOLD responses may help to evaluate and optimize exercise training for improved function.

Understanding The Differential Response Of Multiple Myeloma To Reovirus Treatment

IntroductionMultiple myeloma (MM) is a currently incurable malignancy arising from post germinal, terminally differentiated plasma cells. Despite the success of proteasome inhibitors and immune-modulating drugs such as bortezomib and thalidomide in the treatment of relapsed disease patients eventually become refractory to these drugs making new therapeutic agents a critical need.One potential new agent is Reovirus Serotype 3- Dearing Strain. While infection of immunocompetent hosts results in only minor respiratory illness it has been demonstrated that reovirus selectively replicates in and is cytopathic to Ras activated cells. This specificity is due at least in part to the inhibition of auto-phosphorylation of PKR. The minimal side effects and dependence of reovirus on Ras activation make it an interesting candidate for relapsed/refractory MM as it has been reported that at least 50% of relapsed MM patients have activating Ras mutations and most patients show activation at other Ras checkpoints including p38. While there has been limited investigation of reovirus treatment of MM cell lines there has been less analysis of resistance to reovirus treatment in MM. MethodsMM cell lines were screened via MTS assay to identify cell lines sensitive, intermediate, and resistant to reovirus treatment. Cell lines were then treated at a MOI of 10 or 25 for 9 and 24 hours and analyzed by immunohistochemistry (IHC) for p38, reoviral protein, and caspase-3 as well as in situ hybridization (ISH) and qRT-PCR for reoviral RNA. Total RNA isolates of sensitive, intermediate, and resistant cell lines were used to perform a screening analysis of mRNA, microRNA (miRNA), and long non-coding RNA to identify differential expression. In addition, expression of the reovirus high affinity receptor JAM-1 was assessed in these cell lines by western blot and IHC. Following this analysis mRNA, miRNA, and long non-coding RNA expression was analyzed in bone marrow samples from relapsed/refractory MM patients enrolled in a reovirus monotherapy clinical trial before and after treatment. These results were correlated with patient response and compared to the results from the cell lines. ResultsMTS results clearly identified several cell lines as being sensitive (RPMI), intermediate (H929), and resistant (OPM2) to reovirus treatment according to percent viability. IHC revealed over 98% positivity for p38 in all cell lines indicating Ras activation and permissibility to reovirus infection regardless of sensitivity. IHC also showed a higher percentage of cells positive for reoviral protein in sensitive and intermediate cell lines compared to resistant cell lines. The increased reoviral protein expression in these cell lines correlated with these lines having a higher percentage of caspase-3 positive cells compared to both the controls and the resistant cell lines. ISH demonstrated that the relative signal intensity of reoviral RNA was proportional to the sensitivity of each cell line, and these results were consistent with qRT-PCR results. ConclusionsDespite susceptibility to reovirus infection, as determined by p38 positivity, substantial variation was seen in response to reovirus treatment amongst cell lines. Given the correlation of cell line sensitivity with reoviral RNA levels and reoviral protein production it will be important to identify factors that drive these differences. Ongoing analysis is focused on determining the role of viral entry including expression of the reoviral receptor JAM-1 and subsequent viral trafficking and degradation. In addition, evaluation of differential expression of RNA molecules in cell lines and patient samples is ongoing as miRNA have been identified in the establishment of productive reoviral infections and cancer cell death (Nuovo et al. 2012). Disclosures:No relevant conflicts of interest to declare.Table 1All results are for cells treated at MOI 25 for 24 hours except % viability in which cells were treated at MOI 25 for 48 hours. Values for p38, reovirus protein and caspase-3 represent the percentage of positive cells by IHC. ISH reovirus RNA represents relative signal intensity with 100% being maximum intensity.Cell Line% Viabilityp38Reovirus ProteinCaspase-3 VirusCaspase-3 ControlISH Reovirus RNAAvg. Ct qRT-PCRRPMI2.599.245.359.037.39515.7H92946.398.69.338.517.69019.2OPM287.098.43.642.049.06028.4

Comparison between high-resolution isotropic three-dimensional and high-resolution conventional two-dimensional FSE MR images of the wrist at 3 tesla: A pilot study

To demonstrate the clinical feasibility of high-resolution three-dimensional (3D) isotropic FSE MRI of the wrist by comparing it to high-resolution conventional 2D FSE (2D) MRI. Eleven healthy volunteers were enrolled. All images were obtained at 3 Tesla (T). Delineation of anatomic structures of the wrist, amount of artifact, quality of fat suppression, image blur, and overall quality were qualitatively evaluated. Relative signal intensity (SI) of each structure and relative signal contrast between structures of the wrist were quantitatively measured. The 2D MRI demonstrated significantly higher scores than 3D in anatomic delineation of the SL ligament (P = 0.013), fat suppression (P = 0.013), and image blur (P = 0.003). The remaining quantitative analyses, including overall quality, revealed no statistical significances between 2D and 3D MRI. There were no statistical differences in relative SI of each structure between 2D and 3D imaging, except for bone marrow with fat suppression. There were no significant differences in relative fluid to TFCC and fluid to bone marrow contrast between 2D and 3D imaging, suggesting that both sequences have similar rates of detection for TFCC pathology and bone marrow lesions. With regard to clinical applications, 3D MRI of the wrist has almost equal potential to 2D MRI.

Stable Molecules in N2–H2 Plasmas Measured Using a Quartz Sensor

Stable molecules of N2, H2, and NH3 in N2–H2 plasmas were investigated using a quartz sensor (Q-sensor). Changes in the pressure- and temperature-normalized Q-sensor output (NQO) induced by plasma with radio-frequency (rf) input power were measured near plasma electrodes and shown to correlate to the relative ion signal intensity from NH3. The results confirm that gas composition changes in N2–H2 plasmas can be successfully measured from the NQO changes using the Q-sensor. The spatial distribution of NQO indicates that NH3 molecules are produced near plasma electrodes rather than by secondary gas reactions in the plasma, which also means that Q-sensor measurements can provide information regarding stable gas molecules in plasma.