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PURPOSE: To demonstrate the feasibility of using chemical shift fat-water MRI methods to visualize and measure intrahepatic delivery of ethiodized oil to liver tumors following conventional transarterial chemoembolization (cTACE). MATERIALS AND METHODS: Twenty-eight participants (mean age, 66 years ± 8 [SD]; 22 men) with hepatocellular carcinoma (HCC) treated with cTACE were evaluated with follow-up chemical shift MRI in this Health Insurance Portability and Accountability Act–compliant prospective, institutional review board–approved study. Uptake of ethiodized oil was evaluated at 1-month follow-up chemical shift MRI. Measurements of tumor size (MRI and CT), attenuation and enhancement (CT), fat content percentage, and tumor:normal ratio (MRI) were compared by lesion for responders versus nonresponders, as assessed with modified Response Evaluation Criteria in Solid Tumors and European Association for the Study of the Liver (EASL) criteria. Adverse events and overall survival by the Kaplan-Meier method were secondary end points. RESULTS: Focal tumor ethiodized oil retention was 46% (12 of 26 tumors) at 24 hours and 47% (18 of 38 tumors) at 1 month after cTACE. Tumor volume at CT did not differ between EASL-defined responders and nonresponders (P = .06). Tumor ethiodized oil volume measured with chemical shift MRI was statistically significantly higher for EASL-defined nonresponders (P = .02). Doxorubicin dosing (P = .53), presence of focal fat (P = .83), and a combined end point of focal fat and low doxorubicin dosing (P = .97) did not stratify overall survival after cTACE. CONCLUSION: Chemical shift MRI allowed for assessment of tumor delivery of ethiodized oil out to 1 month after cTACE in participants with HCC and demonstrated tumor ethiodized oil volume as a potential tool for stratification of tumor response by EASL criteria. Keywords: MRI, Chemical Shift Imaging, CT, Hepatic Chemoembolization, Ethiodized Oil Clinicaltrials.gov registration no.: NCT02173119 Supplemental material is available for this article. © RSNA, 2023

Deep learning has been applied to remove artifacts from undersampled MRI and to replace time-consuming signal fitting in quantitative MRI, but these have usually been treated as separate tasks, which does not fully exploit the shared information. This work proposes a new two-stage framework that completes these two tasks in a concerted approach and also estimates the pixel-wise uncertainty levels. Results from accelerated free-breathing radial MRI for liver fat quantification demonstrate that the proposed framework can achieve high image quality from undersampled radial data, high accuracy for liver fat quantification, and detect uncertainty caused by noisy input data. The proposed framework achieved 3-fold acceleration to

Objective Develop an accelerated cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR) sequence to enable clinically feasible myocardial strain evaluation in patients with dilated cardiomyopathy (DCM). Materials and methods A spiral cine DENSE sequence was modified by limiting the field of view in two dimensions using in-plane slice-selective pulses in the stimulated echo. This reduced breath hold duration from 20RR to 14RR intervals. Following phantom and pilot studies, the feasibility of the sequence to assess peak radial, circumferential, and longitudinal strain was tested in control subjects (n = 18) and then applied in DCM patients (n = 29). Results DENSE acquisition was possible in all participants. Elements of the data were not analysable in 1 control (6%) and 4 DCM r(14%) subjects due to off-resonance or susceptibility artefacts and low signal-to-noise ratio. Peak radial, circumferential, short-axis contour strain and longitudinal strain was reduced in DCM patients (p 0.80), except peak radial strain. Discussion We demonstrate the feasibility of CMR strain assessment in healthy controls and DCM patients using an accelerated cine DENSE technique. This may facilitate integration of strain assessment into routine CMR studies. Electronic supplementary material The online version of this article (10.1007/s10334-019-00735-5) contains supplementary material, which is available to authorized users.

Effects of γ-globulin combined with dexamethasone or methylprednisolone in the treatment of acute transverse myelitis (ATM) were investigated. A retrospective analysis of medical records from 136 ATM patients admitted to Linzi District People's Hospital from July 2014 to September 2017 was performed. Patients treated with dexamethasone combined with γ-globulin were in group A (66 cases), and patients treated with methylprednisolone combined with γ-globulin were in group B (70 cases). Clinical efficacy, recovery time of bone marrow function and incidence rate of adverse reactions were analyzed and compared between the two groups. T-lymphocyte subsets in peripheral blood of both groups were detected by Flow cytometry. Quality of life of patients was assessed by the Quality of Life Scale (SF-36) developed by the American Institute of Medicine. Time of sensory recovery, self-walking, improving muscle strength at two levels and urination recovery after treatment in group B were significantly shorter than those in group A (P

This study investigated MRI and semantic segmentation-based deep-learning (SSDL) automation for left-ventricular chamber quantifications (LVCQ) and low longitudinal strain (LLS) determination, thus eliminating user-bias by providing an automated tool to detect cardiotoxicity (CT) in breast cancer patients treated with antineoplastic agents. Displacement Encoding with Stimulated Echoes-based (DENSE) myocardial images from 26 patients were analyzed with the tool’s Convolution Neural Network with underlying Resnet-50 architecture. Quantifications based on the SSDL tool’s output were for LV end-diastolic diameter (LVEDD), ejection fraction (LVEF), and mass (LVM) (see figure for phase sequence). LLS was analyzed with Radial Point Interpolation Method (RPIM) with DENSE phase-based displacements. LVCQs were validated by comparison to measurements obtained with an existing semi-automated vendor tool (VT) and strains by 2 independent users employing Bland-Altman analysis (BAA) and interclass correlation coefficients estimated with Cronbach’s Alpha (C-Alpha) index. F1 score for classification accuracy was 0.92. LVCQs determined by SSDL and VT were 4.6 ± 0.5 vs 4.6 ± 0.7 cm (C-Alpha = 0.93 and BAA = 0.5 ± 0.5 cm) for LVEDD, 58 ± 5 vs 58 ± 6 % (0.90, 1 ± 5%) for LVEF, 119 ± 17 vs 121 ± 14 g (0.93, 5 ± 8 g) for LV mass, while LLS was 14 ± 4 vs 14 ± 3 % (0.86, 0.2 ± 6%). Hence, equivalent LV dimensions, mass and strains measured by VT and DENSE imaging validate our unique automated analytic tool. Longitudinal strains in patients can then be analyzed without user bias to detect abnormalities for the indication of cardiotoxicity and the need for therapeutic intervention even if LVEF is not affected.

Purpose The goal of this study was to determine the accuracy of displacement-encoding with stimulated echoes (DENSE) MRI in a tissue motion phantom with displacements representative of those observed in human brain tissue. Methods The phantom was comprised of a plastic shaft rotated at a constant speed. The rotational motion was converted to a vertical displacement through a camshaft. The phantom generated repeatable cyclical displacement waveforms with a peak displacement ranging from 92 µm to 1.04 mm at 1-Hz frequency. The surface displacement of the tissue was obtained using a laser Doppler vibrometer (LDV) before and after the DENSE MRI scans to check for repeatability. The accuracy of DENSE MRI displacement was assessed by comparing the laser Doppler vibrometer and DENSE MRI waveforms. Results Laser Doppler vibrometer measurements of the tissue motion demonstrated excellent cycle-to-cycle repeatability with a maximum root mean square error of 9 µm between the ensemble-averaged displacement waveform and the individual waveforms over 180 cycles. The maximum difference between DENSE MRI and the laser Doppler vibrometer waveforms ranged from 15 to 50 µm. Additionally, the peak-to-peak difference between the 2 waveforms ranged from 1 to 18 µm. Conclusion Using a tissue phantom undergoing cyclical motion, we demonstrated the percent accuracy of DENSE MRI to measure displacement similar to that observed for in vivo cardiac-induced brain tissue.

Multi‐channel phased receive arrays have been widely adopted for magnetic resonance imaging (MRI) and spectroscopy (MRS). An important step in the use of receive arrays for MRS is the combination of spectra collected from individual coil channels. The goal of this work was to implement an improved strategy termed OpTIMUS (i.e., optimized truncation to integrate multi‐channel MRS data using rank‐R singular value decomposition) for combining data from individual channels. OpTIMUS relies on spectral windowing coupled with a rank‐R decomposition to calculate the optimal coil channel weights. MRS data acquired from a brain spectroscopy phantom and 11 healthy volunteers were first processed using a whitening transformation to remove correlated noise. Whitened spectra were then iteratively windowed or truncated, followed by a rank‐R singular value decomposition (SVD) to empirically determine the coil channel weights. Spectra combined using the vendor‐supplied method, signal/noise2 weighting, previously reported whitened SVD (rank‐1), and OpTIMUS were evaluated using the signal‐to‐noise ratio (SNR). Significant increases in SNR ranging from 6% to 33% (P ≤ 0.05) were observed for brain MRS data combined with OpTIMUS compared with the three other combination algorithms. The assumption that a rank‐1 SVD maximizes SNR was tested empirically, and a higher rank‐R decomposition, combined with spectral windowing prior to SVD, resulted in increased SNR., Optimized truncation to integrate multi‐channel MRS data using rank‐R singular value decomposition (OpTIMUS) is an improved strategy for combining MRS data collected from multi‐channel phased receive arrays that uses a rank‐R decomposition and spectral windowing prior to singular value decomposition (SVD). Spectra combined using OpTIMUS, whitened singular value decomposition (WSVD), signal/noise2 (S/N2) weighting, and the vendor‐supplied method were evaluated using SNR. In vivo spectra combined with OpTIMUS had significantly higher SNR compared with the other three methods.

BACKGROUND AND PURPOSE: Intracranial pressure is estimated invasively by using lumbar puncture with CSF opening pressure measurement. This study evaluated displacement encoding with stimulated echoes (DENSE), an MR imaging technique highly sensitive to brain motion, as a noninvasive means of assessing intracranial pressure status. MATERIALS AND METHODS: Nine patients with suspected elevated intracranial pressure and 9 healthy control subjects were included in this prospective study. Controls underwent DENSE MR imaging through the midsagittal brain. Patients underwent DENSE MR imaging followed immediately by lumbar puncture with opening pressure measurement, CSF removal, closing pressure measurement, and immediate repeat DENSE MR imaging. Phase-reconstructed images were processed producing displacement maps, and pontine displacement was calculated. Patient data were analyzed to determine the effects of measured pressure on pontine displacement. Patient and control data were analyzed to assess the effects of clinical status (pre–lumbar puncture, post–lumbar puncture, or control) on pontine displacement. RESULTS: Patients demonstrated imaging findings suggesting chronically elevated intracranial pressure, whereas healthy control volunteers demonstrated no imaging abnormalities. All patients had elevated opening pressure (median, 36.0 cm water), decreased by the removal of CSF to a median closing pressure of 17.0 cm water. Patients pre–lumbar puncture had significantly smaller pontine displacement than they did post–lumbar puncture after CSF pressure reduction (P = .001) and compared with controls (P = .01). Post–lumbar puncture patients had statistically similar pontine displacements to controls. Measured CSF pressure in patients pre– and post–lumbar puncture correlated significantly with pontine displacement (r = 0.49; P = .04). CONCLUSIONS: This study establishes a relationship between pontine displacement from DENSE MR imaging and measured pressure obtained contemporaneously by lumbar puncture, providing a method to noninvasively assess intracranial pressure status in idiopathic intracranial hypertension.

Purpose Diffusion-weighted Magnetic Resonance Imaging (DWI) has been shown to be a powerful tool for cancer detection with high tumor-to-tissue contrast. This study aims to investigate the feasibility of developing a four-dimensional DWI technique (4D-DWI) for imaging respiratory motion for radiation therapy applications. Materials/methods Image acquisition was performed by repeatedly imaging a volume of interest (VOI) using an interleaved multislice single-shot echo-planar imaging (EPI) 2D-DWI sequence in the axial plane. Each 2D-DWI image was acquired with an intermediately low b-value (b = 500 s/mm2 ) and with diffusion-encoding gradients in x, y, and z diffusion directions. Respiratory motion was simultaneously recorded using a respiratory bellow, and the synchronized respiratory signal was used to retrospectively sort the 2D images to generate 4D-DWI. Cine MRI using steady-state free precession was also acquired as a motion reference. As a preliminary feasibility study, this technique was implemented on a 4D digital human phantom (XCAT) with a simulated pancreas tumor. The respiratory motion of the phantom was controlled by regular sinusoidal motion profile. 4D-DWI tumor motion trajectories were extracted and compared with the input breathing curve. The mean absolute amplitude differences (D) were calculated in superior-inferior (SI) direction and anterior-posterior (AP) direction. The technique was then evaluated on two healthy volunteers. Finally, the effects of 4D-DWI on apparent diffusion coefficient (ADC) measurements were investigated for hypothetical heterogeneous tumors via simulations. Results Tumor trajectories extracted from XCAT 4D-DWI were consistent with the input signal: the average D value was 1.9 mm (SI) and 0.4 mm (AP). The average D value was 2.6 mm (SI) and 1.7 mm (AP) for the two healthy volunteers. Conclusion A 4D-DWI technique has been developed and evaluated on digital phantom and human subjects. 4D-DWI can lead to more accurate respiratory motion measurement. This has a great potential to improve the visualization and delineation of cancer tumors for radiotherapy.

PURPOSE To determine the optimal respiratory navigator gating configuration for the quantification of left ventricular strain using spiral cine displacement encoding with stimulated echoes (DENSE) MRI. MATERIALS AND METHODS Two-dimensional spiral cine DENSE was performed on a 3 Tesla MRI using two single-navigator configurations (retrospective, prospective) and a combined "dual-navigator" configuration in 10 healthy adults and 20 healthy children. The adults also underwent breathhold DENSE as a reference standard for comparisons. Peak left ventricular strains, signal-to-noise ratio (SNR), and navigator efficiency were compared. Subjects also underwent dual-navigator gating with and without visual feedback to determine the effect on navigator efficiency. RESULTS There were no differences in circumferential, radial, and longitudinal strains between navigator-gated and breathhold DENSE (P = 0.09-0.95) (as confidence intervals, retrospective: [-1.0%-1.1%], [-7.4%-2.0%], [-1.0%-1.2%]; prospective: [-0.6%-2.7%], [-2.8%-8.3%], [-0.3%-2.9%]; dual: [-1.6%-0.5%], [-8.3%-3.2%], [-0.8%-1.9%], respectively). The dual configuration maintained SNR compared with breathhold acquisitions (16 versus 18, P = 0.06). SNR for the prospective configuration was lower than for the dual navigator in adults (P = 0.004) and children (P

Purpose To describe and assess an automated normalization method for identifying sentinel (septal) regions of myocardial dysfunction in nonischemic, nonvalvular dilated cardiomyopathy (DCM), using an unprecedented combination of the navigator-gated 3D spiral displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI), radial point interpolation (RPIM) and multiparametric strain z-score (MPZS). Materials and methods Navigator-gated 3D spiral DENSE, in a 1.5T MRI machine, was used for acquiring the displacement encoded complex images, MR Analytical Software System (MASS) for automated boundary detection and automated meshfree RPIM for left-ventricular (LV) myocardial strain computation to analyze MPZS in 36 subjects (with n = 17 DCM patients). Pearson's r correlation established relations between global/sentinel MPZS and ejection fraction (EF). The time taken for combined RPIM-MPZS computations was recorded. Results Maximum MPZS differences were seen between anteroseptal and posterolateral regions in the base (2.0 ± 0.3 vs. 0.9 ± 0.5) and the mid-wall (2.1 ± 0.4 vs. 1.0 ± 0.4). These regional differences were found to be consistent with historically documented septal injury in nonischemic DCM. Correlations were 0.6 between global MPZS and EF, and 0.7 between sentinel MPZS and EF. The time taken for combined RPIM-MPZS computations per subject was 18.9 ± 5.9 seconds. Conclusion Heterogeneous contractility found in the sentinel regions with the current automated MPZS computation scheme and the correlation found between MPZS and EF may lead to the creation of a new clinical metric in LV DCM surveillance. J. MAGN. RESON. IMAGING 2016;44:993-1002.

Purpose To investigate the prognostic value of circumferential left ventricular (LV) strain measured by using cardiac MRI for prediction of major adverse cardiac events (MACE) following an acute ST-segment-elevation myocardial infarction (STEMI). Materials and Methods Participants with acute STEMI were prospectively enrolled from May 11, 2011, to November 22, 2012. Cardiac MRI was performed at 1.5 T during the index hospitalization. Displacement encoding with stimulated echoes (DENSE) and feature tracking of cine cardiac MRI was used to assess circumferential LV strain. MACE that occurred after discharge were independently assessed by cardiologists blinded to the baseline observations. Results A total of 259 participants (mean age, 58 years ± 11 [standard deviation]; 198 men [mean age, 58 years ± 11] and 61 women [mean age, 58 years ± 12]) underwent cardiac MRI 2.2 days ± 1.9 after STEMI. Average infarct size was 18% ± 13 of LV mass and circumferential strain was -13% ± 3 (DENSE method) and -24% ± 7 (feature- tracking method). Fifty-one percent (131 of 259 participants) had presence of microvascular obstruction. During a median follow-up period of 4 years, 8% (21 of 259) experienced MACE. Area under the curve (AUC) for DENSE was different from that of feature tracking (AUC, 0.76 vs 0.62; P = .03). AUC for DENSE was similar to that of initial infarct size (P = .06) and extent of microvascular obstruction (P = .08). DENSE-derived strain provided incremental prognostic benefit over infarct size for prediction of MACE (hazard ratio, 1.3; P.01). Conclusion Circumferential strain has independent prognostic importance in study participants with acute ST-segment-elevation myocardial infarction. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Kramer in this issue.

Objective We hypothesized that Displacement Encoding with Stimulated Echoes (DENSE) and feature-tracking derived circumferential strain would provide incremental prognostic value over the extent of infarction for recovery of segmental myocardial function. Methods Two hundred and sixty-one patients (mean age 59 years, 73% male) underwent MRI 2 days post-ST elevation myocardial infarction (STEMI) and 241 (92%) underwent repeat imaging 6 months later. The MRI protocol included cine, 2D-cine DENSE, T2 mapping and late enhancement. Wall motion scoring was assessed by 2-blinded observers and adjudicated by a third. (WMS: 1=normal, 2=hypokinetic, 3=akinetic, 4=dyskinetic). WMS improvement was defined as a decrease in WMS ≥ 1, and normalization where WMS = 1 on follow-up. Segmental circumferential strain was derived utilizing DENSE and feature-tracking. A generalized linear mixed model with random effect of subject was constructed and used to account for repeated sampling when investigating predictors of segmental myocardial improvement or normalization Results At baseline and follow-up, 1416 segments had evaluable data for all parameters. Circumferential strain by DENSE (p

Introduction Displacement encoding with stimulated echoes (DENSE) is a phase contrast technique that encodes tissue displacement into phase images, which are typically processed into measures of cardiac function such as strains. For improved signal to noise ratio and spatiotemporal resolution, DENSE is often acquired with a spiral readout using an 11.1 ms readout duration. However, long spiral readout durations are prone to blurring due to common phenomena such as off-resonance and T2* decay, which may alter the resulting quantifications of strain. We hypothesized that longer readout durations would reduce image quality and underestimate cardiac strains at both 3.0 T and 1.5 T and that using short readout durations could overcome these limitations. Material and methods Computational simulations were performed to investigate the relationship between off-resonance and T2* decay, the spiral cine DENSE readout duration, and measured radial and circumferential strain. Five healthy participants subsequently underwent 2D spiral cine DENSE at both 3.0 T and 1.5 T with several different readout durations 11.1 ms and shorter. Pearson correlations were used to assess the relationship between cardiac strains and the spiral readout duration. Results Simulations demonstrated that long readout durations combined with off-resonance and T2* decay yield blurred images and underestimate strains. With the typical 11.1 ms DENSE readout, blurring was present in the anterior and lateral left ventricular segments of participants and was markedly improved with shorter readout durations. Radial and circumferential strains from those segments were significantly correlated with the readout duration. Compared to the 1.9 ms readout, the 11.1 ms readout underestimated radial and circumferential strains in those segments at both field strengths by up to 19.6% and 1.5% (absolute), or 42% and 7% (relative), respectively. Conclusions Blurring is present in spiral cine DENSE images acquired at both 3.0 T and 1.5 T using the typical 11.1 ms readout duration, which yielded substantially reduced radial strains and mildly reduced circumferential strains. Clinical studies using spiral cine DENSE should consider these limitations, while future technical advances may need to leverage accelerated techniques to improve the robustness and accuracy of the DENSE acquisition rather than focusing solely on reduced acquisition time.

Author(s): Ferreira, Pedro F; Nielles-Vallespin, Sonia; Scott, Andrew D; de Silva, Ranil; Kilner, Philip J; Ennis, Daniel B; Auger, Daniel A; Suever, Jonathan D; Zhong, Xiaodong; Spottiswoode, Bruce S; Pennell, Dudley J; Arai, Andrew E; Firmin, David N | Abstract: PurposeTo evaluate the importance of strain-correcting stimulated echo acquisition mode echo-planar imaging cardiac diffusion tensor imaging.MethodsHealthy pigs (n = 11) were successfully scanned with a 3D cine displacement-encoded imaging with stimulated echoes and a monopolar-stimulated echo-planar imaging diffusion tensor imaging sequence at 3 T during diastasis, peak systole, and strain sweet spots in a midventricular short-axis slice. The same diffusion tensor imaging sequence was repeated ex vivo after arresting the hearts in either a relaxed (KCl-induced) or contracted (BaCl2 -induced) state. The displacement-encoded imaging with stimulated echoes data were used to strain-correct the in vivo cardiac diffusion tensor imaging in diastole and systole. The orientation of the primary (helix angles) and secondary (E2A) diffusion eigenvectors was compared with and without strain correction and to the strain-free ex vivo data.ResultsStrain correction reduces systolic E2A significantly when compared without strain correction and ex vivo (median absolute E2A = 34.3° versus E2A = 57.1° (P = 0.01), E2A = 60.5° (P = 0.006), respectively). The systolic distribution of E2A without strain correction is closer to the contracted ex vivo distribution than with strain correction, root mean square deviation of 0.027 versus 0.038.ConclusionsThe current strain-correction model amplifies the contribution of microscopic strain to diffusion resulting in an overcorrection of E2A. Results show that a new model that considers cellular rearrangement is required. Magn Reson Med 79:2205-2215, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Regional tissue mechanics play a fundamental role in the patient-specific function and remodeling of the cardiovascular system. Nevertheless, regional in vivo assessments of aortic kinematics remain lacking due to the challenge of imaging the thin aortic wall. Herein, we present a novel application of displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) to quantify the regional displacement and circumferential Green strain of the thoracic and abdominal aorta. Two-dimensional (2D) spiral cine DENSE and steady-state free procession (SSFP) cine images were acquired at 3T at either the infrarenal abdominal aorta (IAA), descending thoracic aorta (DTA), or distal aortic arch (DAA) in a pilot study of six healthy volunteers (22–59 y.o., 4 females). DENSE data were processed with multiple custom noise reduction techniques including time-smoothing, displacement vector smoothing, sectorized spatial smoothing, and reference point averaging to calculate circumferential Green strain across 16 equispaced sectors around the aorta. Each volunteer was scanned twice to evaluate interstudy repeatability. Circumferential Green strain was heterogeneously distributed in all volunteers and locations. The mean spatial heterogeneity index (standard deviation of all sector values divided by the mean strain) was 0.37 in the IAA, 0.28 in the DTA, and 0.59 in the DAA. Mean (homogenized) peak strain by DENSE for each cross section was consistent with the homogenized linearized strain estimated from SSFP cine. The mean difference in peak strain across all sectors following repeat imaging was −0.1±2.3%, with a mean absolute difference of 1.7%. Aortic cine DENSE MRI is a viable noninvasive technique for quantifying heterogeneous regional aortic wall strain and has significant potential to improve patient-specific clinical assessments of numerous aortopathies, as well as to provide the lacking spatiotemporal data required to refine patient-specific computational models of aortic growth and remodeling.

To develop a Shared K-space (SharK) magnetic resonance imaging (MRI) sequence that combines angiographic and late gadolinium enhancement (LGE) acquisitions to improve atrial wall segmentation and scar identification, and to develop a novel visualization method that quantifies scar encirclement of pulmonary veins postablation treatment for atrial fibrillation.A SharK sequence was developed and used at 3T to image the left atrium in 11 patients postcryoballoon ablation. The effects of sharing k-space between the angiographic and LGE acquisitions on the accuracy of scar were assessed. The left atrial wall was segmented and points about each pulmonary vein (PV) ostia were projected onto a bullseye to quantitatively compare PV encirclement. The parameters used to quantify encirclement were varied to perform a sensitivity analysis.Compared to using a complete set of k-space, total atrial scar differences were significant only when sharing75% k-space (P = 0.014), and 90% sensitivity and specificity for identifying scar was achieved when sharing 50% k-space. In patients, the right PVs showed more intersubject variance in encirclement compared to the left PVs. A 100° anteroinferior portion of the left PVs was always encircled, while the superior segments of both right PVs was ablated in only 6/11 patients.A SharK sequence was developed to combine angiographic and LGE imaging for atrial wall segmentation and scar identification. The PV bullseye quantifies and localizes encirclement about the PVs. The left PVs showed a higher amount of scar encirclement and less variability compared to the right PVs.2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:477-486.

Purpose Fast cine displacement encoding with stimulated echoes (DENSE) MR has higher spatial resolution and enables rapid postprocessing. Thus we compared the accuracy of regional strains computation by DENSE with tagged MR in healthy and non-ischemic, non-valvular dilated cardiomyopathy (DCM) subjects. Materials and Methods Validation of three-dimensional regional strains computed with DENSE was conducted in reference to standard tagged MRI (TMRI) in healthy subjects and patients with DCM. Additional repeatability studies in healthy subjects were conducted to increase confidence in DENSE. A meshfree multiquadrics radial point interpolation method (RPIM) was used for computing Lagrange strains in sixteen left ventricular segments. Bland-Altman analysis and Student's t-tests were conducted to observe similarities in regional strains between sequences and in DENSE repeatability studies. Results Regional circumferential strains ranged from −0.21 ± 0.07 (Lateral–Apex) to −0.11 ± 0.05 (Posterorseptal–Base) in healthy subjects and −0.15 ± 0.04 (Anterior–Apex) to −0.02 ± 0.08 (Posterorseptal–Base) in DCM patients. Computed mean differences in regional circumferential strain from the DENSE-TMRI comparison study was 0.01 ± 0.03 (95% limits of agreement) in normal subjects, −0.01 ± 0.06 in DCM patients and 0.0 ± 0.02 in repeatability studies, with similar agreements in longitudinal and radial strains. Conclusion We found agreement between DENSE and tagged MR in patients and volunteers in terms of evaluation of regional strains. J. Magn. Reson. Imaging 2015;41:386–396.© 2013 Wiley Periodicals, Inc.

Ultrafine sub-5 nm magnetic iron oxide nanoparticles coated with oligosaccharides (SIO) with dual T1–T2 weighted contrast enhancing effects and fast clearance have been developed as magnetic resonance imaging (MRI) contrast agents. Excellent water solubility, biocompatibility and high stability of such sub-5 nm SIO nanoparticles were achieved by using the “in situ polymerization” coating method, which enables glucose to form oligosaccharides directly on the surface of hydrophobic iron oxide nanocrystals. Reported ultrafine SIO nanoparticles exhibit a longitudinal relaxivity (r1) of 4.1 mM−1 s−1 and a r1/r2 ratio of 0.25 at 3 T (clinical field strength), rendering improved T1 or “brighter” contrast enhancement in T1-weighted MRI in addition to typical T2 or “darkening” contrast of conventional iron oxide nanoparticles. Such dual contrast effects can be demonstrated by liver imaging with T2 “darkening” contrast in the liver parenchyma but T1 “bright” contrast in the hepatic vasculature. More importantly, this new class of ultrafine sub-5 nm iron oxide nanoparticles showed much faster body clearance than those with larger sizes, promising better safety for clinical applications.

Unfortunately the article was published with a spell error in the co-author names “Ankur Pandy and Pallavi Pandy”. The correct co-author names should be Ankur Pandey and Pallavi Pandey”.

MAGNETIC IRON OXIDE NANOPARTICLES (IONPs) have been used as contrast agents of magnetic resonance imaging (MRI) for diagnostic imaging (1-3) and more recently for developing MRI-based molecular imaging probes in various biomedical applications, including cell tracking (4,5), biomarker targeted cancer imaging (6-8), and image guided drug delivery (9-11). IONPs, as a superparamagnetic agent, primarily shorten transverse relaxation times, ie, T2 and T2*, which leads to prominent signal decrease or "negative contrast" of targeted tissue on T2- and T2*-weighted images (12-14). The typical drawback of the T2- and T2*-weighted negative contrast is its poor sensitivity when used to study areas with low background signal. In addition, T2- and T2*-weighted imaging methods are also vulnerable to blooming artifacts and the partial volume errors from the effect of local magnetic inhomogeneity and high susceptibility of paramagnetic IONPs (15,16), making accurate localization and quantitative imaging of magnetic nanoparticles more difficult. It should also be mentioned that further improvement of negative contrast is limited by the threshold of the negative contrast which is the difference between the signal level of IONP affected area and signal intensity of zero (17). Therefore, conventional T2- and T2*-weighted imaging methods may not be able to take advantage of those magnetic nanoparticle probes with very high r2 relaxivity or increase of the dosage of administered IONPs because of the threshold of the negative contrast, as the maximal contrast that the negative contrast can reach is the signal intensity of zero. Therefore, a method of generating positive contrast from magnetic nanoparticles, ie, signal brightening, to improve the detection, and even quantification, of magnetic nanoparticles is desirable and has attracted increasing effort in translating magnetic nanoparticle imaging probes to broader applications (18-20). A number of approaches have been investigated to obtain positive contrast from IONPs, including ultrashort echo time (UTE) imaging (18,21,22), off-resonance saturation (ORS) techniques (23), sweep imaging with Fourier transformation (SWIFT) (24-27), phase contrast (28-30) and, most recently, adiabatic imaging (31,32). Among them, UTE imaging offers a relatively simple strategy by taking advantage of high longitudinal relaxivity r1 of IONPs while reducing the contribution of predominant T2 and T2* and spin dephase effects of IONPs that are also sources of imaging artifacts. With a very short echo time, typically below 0.1 msec, UTE imaging enables capturing signal enhancement from T1 effect with little influence of signal decay from the T2 and T2* effect, allowing for obtaining positive contrast on T1-weighted UTE images. Furthermore, the signal enhancement obtained from the UTE imaging is a function of T1 relaxation times of IONPs at different core sizes and concentrations in a certain range (18). A recent study by Girard et al (22) discussed the general strategy to optimize IONP detection sensitivity using UTE imaging. Through detailed computer simulation, imaging experiments on IONP phantoms in vitro and a proof-of-concept mouse model bearing human prostate tumors in vivo, it was shown that UTE imaging and subtraction of a longer echo signal from that of the UTE (SubUTE) were good approaches for imaging of IONP. In the present study, we report further investigation and application of UTE and SubUTE imaging for the detection and visualization of the receptor targeted IONP imaging probes in cancer xenograft mouse models using positive contrast enhancement. The main purpose was to demonstrate the capability of UTE imaging to obtain positive contrast from biomarker targeted magnetic nanoparticle probes selectively accumulated in the human pancreatic and breast cancer xenograft models in the mice in vivo.

To determine the optimal respiratory navigator gating configuration for the quantification of left ventricular strain using spiral cine displacement encoding with stimulated echoes (DENSE) MRI.Two-dimensional spiral cine DENSE was performed on a 3 Tesla MRI using two single-navigator configurations (retrospective, prospective) and a combined "dual-navigator" configuration in 10 healthy adults and 20 healthy children. The adults also underwent breathhold DENSE as a reference standard for comparisons. Peak left ventricular strains, signal-to-noise ratio (SNR), and navigator efficiency were compared. Subjects also underwent dual-navigator gating with and without visual feedback to determine the effect on navigator efficiency.There were no differences in circumferential, radial, and longitudinal strains between navigator-gated and breathhold DENSE (P = 0.09-0.95) (as confidence intervals, retrospective: [-1.0%-1.1%], [-7.4%-2.0%], [-1.0%-1.2%]; prospective: [-0.6%-2.7%], [-2.8%-8.3%], [-0.3%-2.9%]; dual: [-1.6%-0.5%], [-8.3%-3.2%], [-0.8%-1.9%], respectively). The dual configuration maintained SNR compared with breathhold acquisitions (16 versus 18, P = 0.06). SNR for the prospective configuration was lower than for the dual navigator in adults (P = 0.004) and children (P 0.001). Navigator efficiency was higher (P 0.001) for both retrospective (54%) and prospective (56%) configurations compared with the dual configuration (35%). Visual feedback improved the dual configuration navigator efficiency to 55% (P 0.001).When quantifying left ventricular strains using spiral cine DENSE MRI, a dual navigator configuration results in the highest SNR in adults and children. In adults, a retrospective configuration has good navigator efficiency without a substantial drop in SNR. Prospective gating should be avoided because it has the lowest SNR. Visual feedback represents an effective option to maintain navigator efficiency while using a dual navigator configuration.2 J. Magn. Reson. Imaging 2017;45:786-794.

Purpose To assess myocardial strain using cine displacement encoding with stimulated echoes (DENSE) using 1.5T and 3.0T MRI in healthy adults. Materials and Methods Healthy adults without any history of cardiovascular disease underwent magnetic resonance imaging (MRI) at 1.5T and 3.0T within 2 days. The MRI protocol included balanced steady‐state free‐precession (b‐SSFP), 2D cine‐echo planar imaging (EPI)‐DENSE, and late gadolinium enhancement in subjects >45 years. Acquisitions were divided into six segments; global and segmental peak longitudinal and circumferential strain were derived and analyzed by field strength, age, and gender. Results In all, 89 volunteers (mean age 44.8 ± 18.0 years, range: 18–87 years) underwent MRI at 1.5T, and 88 of these subjects underwent MRI at 3.0T (1.4 ± 1.4 days between the scans). Compared with 3.0T, the magnitudes of global circumferential (–19.5 ± 2.6% vs. –18.47 ± 2.6%; P = 0.001) and longitudinal (–12.47 ± 3.2% vs. –10.53 ± 3.1%; P = 0.004) strain were greater at 1.5T. At 1.5T, longitudinal strain was greater in females than in males: –10.17 ± 3.4% vs. –13.67 ± 2.4%; P = 0.001. Similar observations occurred for circumferential strain at 1.5T (–18.72 ± 2.2% vs. –20.10 ± 2.7%; P = 0.014) and at 3.0T (–17.92 ± 1.8% vs. –19.1 ± 3.1%; P = 0.047). At 1.5T, longitudinal and circumferential strain were not associated with age after accounting for sex (longitudinal strain P = 0.178, circumferential strain P = 0.733). At 3.0T, longitudinal and circumferential strain were associated with age (P < 0.05). Longitudinal strain values were greater in the apico‐septal, basal‐lateral, and mid‐lateral segments and circumferential strain in the inferior, infero‐lateral, and antero‐lateral LV segments. Conclusion Myocardial strain parameters as revealed by cine‐DENSE at different MRI field strengths were associated with myocardial region, age, and sex. J. Magn. Reson. Imaging 2016;44:1197–1205.

Tourism system reform in large level is helpful to promote the development of tourism industry and the market economy in our country. At present, our country's tourism administration has some prominent problems, and it is necessary to formulate the corresponding reform measures. The paper mainly discusses the problem status of the tourism administration and formulates reform countermeasures. Tourism is the third largest industry in China, and also a kind of industry emerged after reform and opening up. The development of a regional tourism helps to promote the region's economic development and social progress. In general, the tourism industry in our country has experienced three stages of development, and each stage of the development promotes tourism in one step forward. Tourism industry and the market economy system in China are in very close relationship. The development of tourism industry, at the same time also contributes to the change of the market economy system in our country. There are some problems in current tourism management system, and it is necessary to solve them in time. How to further improve tourism management department function, innovate management system, coordinate tourism enterprises' efficient and orderly operation are important problems need to be solved (1). Innovate tourism economy system in our country, at the same time; strengthen the propaganda to promote the development of China's tourism industry. THE PRESENT SITUATION AND PROBLEMS IN TOURISM MANAGEMENT

Engineering and functionalizing magnetic nanoparticles have been an area of the extensive research and development in the biomedical and nanomedicine fields. Because their biocompatibility and toxicity are well investigated and better understood, magnetic nanoparticles, especially iron oxide nanoparticles, are better suited materials as contrast agents for magnetic resonance imaging (MRI) and for image-directed delivery of therapeutics. Given tunable magnetic properties and various surface chemistries from the coating materials, most applications of engineered magnetic nanoparticles take advantages of their superb MRI contrast enhancing capability as well as surface functionalities. It has been found that MRI contrast enhancement by magnetic nanoparticles is highly dependent on the composition, size and surface properties as well as the degree of aggregation of the nanoparticles. Therefore, understanding the relationships between these intrinsic parameters and the relaxivities that contribute to MRI contrast can lead to establishing essential guidance that may direct the design of engineered magnetic nanoparticles for theranostics applications. On the other hand, new contrast mechanism and imaging strategy can be developed based on the novel properties of engineered magnetic nanoparticles. This review will focus on discussing the recent findings on some chemical and physical properties of engineered magnetic nanoparticles affecting the relaxivities as well as the impact on MRI contrast. Furthermore, MRI methods for imaging magnetic nanoparticles including several newly developed MRI approaches aiming at improving the detection and quantification of the engineered magnetic nanoparticles are described.

Varieties of magnetic nanoparticles have been introduced as contrast agents for MRI and molecular imaging probes because of their superb ability in shortening transverse relaxation times T2 and T2*, which leads to a strong decrease in signal intensity of target organs or so called “negative contrast” on conventional T2-weighted images (1,2). However, the typical drawback of the negative contrast is its poor contrast when used to study areas that have low background signals. It is challenging to image magnetic nanoparticle labeled cells or magnetic nanoparticle based molecular imaging probes with negative contrast, which accumulate in the organs and tissues in the area with high magnetic inhomogeneity or susceptibility effect, e.g., bone marrow and lung, due to the intrinsic tissue signal void. Because of the magnetic susceptibility induced by the strong dephase effect of magnetic nanoparticles, T2 and T2* weighted imaging methods are also vulnerable to the “blooming” artifacts and partial volume effects (3,4), making accurate localization and quantitative imaging difficult. Furthermore, higher magnetic susceptibility and stronger T2 effect from large sized magnetic nanoparticles may not be translated to better negative contrast in the T2-weighted imaging, as the contrast may not improve further as the level of signal decrease cannot get beyond voiding the signal from its original level (5). To overcome these limitations, there are significant efforts in developing alternative imaging methods that are capable of enhancing the signal or generating bright and positive contrast (6–10). For example, several off-resonance imaging techniques have been investigated to image the off-resonant spins of the tissue due to the influence of magnetic nanoparticles to generate positive contrast (9,10). On the other hand, it is known that magnetic nanoparticles also exhibit a higher longitudinal relaxivity, providing intrinsic signal enhancement on T1-weighted images (11–13). Conventional T1-weighted sequences have been tested for this positive contrast mechanism in magnetic nanoparticles based MR angiography (14). However, conventional imaging sequences cannot fully take advantage of such strong T1-weighted contrast effect because of the predominant T2 and spin dephase effects of magnetic nanoparticles. Ultrashort echo time (UTE) imaging is capable of imaging materials with extremely short T2 and very fast signal decay (15,16). With very short echo time (TE), typically below 0.1 ms, UTE imaging allows for signal acquisition with little T2 influence. In this study, a UTE imaging sequence was applied to obtain T1-weighted positive contrast enhancement from magnetic iron oxide nanoparticles (IONPs) with high r1 and r2 relaxivities. Signal enhancement obtained from the UTE imaging was found to be a function of the T1 relaxation times of the IONPs at different core sizes and concentrations. In addition, the relative-contrast-to-water (RCW) ratios were calculated for UTE images and compared with those of T2-weighted images. The UTE imaging was further tested for the positive contrast imaging of U87MG human glioblastoma cells targeted with an IONP conjugated with a small peptide ligand of arginine-glycine-aspartic acid (RGD), which has a high affinity to the cells overexpressing αvβ3 integrin.

Objective: Displacement ENcoding with Stimulated Echoes (DENSE) is an MRI technique developed to encode phase related to myocardial tissue displacements, and the displacement information directly applied towards detecting left-ventricular (LV) myocardial motion during the cardiac cycle. The purpose of this study is to present a novel, three-dimensional (3D) DENSE displacement-based and magnitude image quantization-based, semi-automated detection technique for myocardial wall motion, whose boundaries are used for rapid and automated computation of 3D myocardial strain. Methods: The architecture of this boundary detection algorithm is primarily based on pixelwise spatiotemporal increments in LV tissue displacements during the cardiac cycle and further reinforced by radially searching for pixel-based image gradients in multithreshold quantized magnitude images. This spatiotemporal edge detection methodology was applied to all LV partitions and their subsequent timeframes that lead to full 3D LV reconstructions. It was followed by quantifications of 3D chamber dimensions and myocardial strains, whose rapid computation was the primary motivation behind developing this algorithm. A pre-existing two-dimensional (2D) semi-automated contouring technique was used in parallel to validate the accuracy of the algorithm and both methods tested on DENSE data acquired in (N = 14) healthy subjects. Chamber quantifications between methods were compared using paired t-tests and Bland–Altman analysis established regional strain agreements. Results: There were no significant differences in the results of chamber quantifications between the 3D semi-automated and existing 2D boundary detection techniques. This included comparisons of ejection fractions, which were 0.62 ± 0.04 vs 0.60 ± 0.06 (p = 0.23) for apical, 0.60 ± 0.04 vs 0.59 ± 0.05 (p = 0.76) for midventricular and 0.56 ± 0.04 vs 0.58 ± 0.05 (p = 0.07) for basal segments, that were quantified using the 3D semi-automated and 2D pre-existing methodologies, respectively. Bland–Altman agreement between regional strains generated biases of 0.01 ± 0.06, –0.01 ± 0.01 and 0.0 ± 0.06 for the radial, circumferential and longitudinal directions, respectively. Conclusion: A new, 3D semi-automated methodology for contouring the entire LV and rapidly generating chamber quantifications and regional strains is presented that was validated in relation to an existing 2D contouring technique. Advances in knowledge: This study introduced a scientific tool for rapid, semi-automated generation of clinical information regarding shape and function in the 3D LV.

Cardiac-synchronized brain motion is well documented, but the accurate measurement of such motion on the pixel-by-pixel basis has been hampered by the lack of proper imaging technique. In this article, the authors present the implementation of an autotracking spiral cine displacement-encoded stimulation echo (DENSE) magnetic resonance imaging (MRI) technique for the measurement of pulsatile brain motion during the cardiac cycle. Displacement-encoded dynamic MR images of three healthy volunteers were acquired throughout the cardiac cycle using the spiral cine-DENSE pulse sequence gated to the R wave of an electrocardiogram. Pixelwise Lagrangian displacement maps were computed, and 2D displacement as a function of time was determined for selected regions of interests. Different intracranial structures exhibited characteristic motion amplitude, direction, and pattern throughout the cardiac cycle. Time-resolved displacement curves revealed the pathway of pulsatile motion from brain stem to peripheral brain lobes. These preliminary results demonstrated that the spiral cine-DENSE MRI technique can be used to measure cardiac-synchronized pulsatile brain motion on the pixel-by-pixel basis with high temporal/spatial resolution and sensitivity.

Defining myocardial contours is often the most time-consuming portion of dynamic cardiac MRI image analysis. Displacement encoding with stimulated echoes (DENSE) is a quantitative MRI technique that encodes tissue displacement into the phase of the complex MRI images. Cine DENSE provides a time series of these images, thus facilitating the non-invasive study of myocardial kinematics. Epicardial and endocardial contours need to be defined at each frame on cine DENSE images for the quantification of regional displacement and strain as a function of time. This work presents a reliable and effective two-dimensional semi-automated segmentation technique that uses the encoded motion to project a manually-defined region of interest through time. Contours can then easily be extracted for each cardiac phase. This method boasts several advantages, including, (1) parameters are based on practical physiological limits, (2) contours are calculated for the first few cardiac phases, where it is difficult to visually distinguish blood from myocardium, and (3) the method is independent of the shape of the tissue delineated and can be applied to short- or long-axis views, and on arbitrary regions of interest. Motion-guided contours were compared to manual contours for six conventional and six slice-followed mid-ventricular short-axis cine DENSE datasets. Using an area measure of segmentation error, the accuracy of the segmentation algorithm was shown to be similar to inter-observer variability. In addition, a radial segmentation error metric was introduced for short-axis data. The average radial epicardial segmentation error was 0.36 ± 0.08 and 0.40 ± 0.10 pixels for slice-followed and conventional cine DENSE, respectively, and the average radial endocardial segmentation error was 0.46 ± 0.12 and 0.46 ± 0.16 pixels for slice following and conventional cine DENSE, respectively. Motion-guided segmentation employs the displacement-encoded phase shifts intrinsic to DENSE MRI to accurately propagate a single set of pre-defined contours throughout the remaining cardiac phases.

The objective of this study was to apply cine magnetic resonance imaging (MRI) using displacement encoding with stimulated echoes (DENSE) to measure the dynamic two-dimensional (2D) displacement and Lagrangian strain fields in the biceps brachii muscle. Six healthy volunteers underwent cine DENSE MRI during repeated elbow flexion against the load of gravity. Displacement encoded dynamic images of the upper arm were acquired with spatial and temporal resolutions of 1.9 × 1.9 mm2 and 30 ms, respectively. Pixel-wise Lagrangian displacement and strain fields were calculated from the measured images. We extracted first and second principal strains (E1 and E2) along the centerline and anterior regions of the muscle. E1 and E2 were relatively uniform along the anterior region. However, E1 and E2 were both nonuniform along the centerline region – normalized values for E1 and E2 varied over the ranges of 0.27 to 1.35, and 0.45 to 2.36, respectively. The directions of the first and second principal strains varied throughout the muscle and showed that the direction of principal shortening is not necessarily aligned with fascicle direction. This study demonstrates the utility of cine DENSE MR imaging for analyzing skeletal muscle mechanics and provides data describing the in vivo mechanics of muscle tissue to a level of detail that has not been previously possible.

The study evaluates the overall effectiveness of intervention programs among female sex workers in a Chinese community.Behavioral surveillance data in 2003, 2004, and 2005 obtained from 2 communities (intervened and control) were compared.The baseline data (2003) of the 2 counties were not significantly different. In 2004 and 2005, the intervened county had significantly higher prevalence of condom use with their clients and regular sex partners (last-time and consistent use in the last month; OR = 2.2-33.2 in 2004 and 3.8-8.3 in 2005), higher HIV-related knowledge level (OR = 7.9 in 2004 and 17.3 in 2005), and lower STD prevalence (OR = 0.22 in 2004 and 0.11 in 2005). Coverage rates of HIV antibody testing and HIV-related services increased in the intervened county but decreased in the control county.Intervention programs may result in substantial behavioral changes in a community within a few years.

Background Displacement Encoding with Stimulated Echoes (DENSE) encodes displacement into the phase of the magnetic resonance signal. The encoding frequency (ke) maps the measured phase to tissue displacement while the strength of the encoding gradients affects image quality. 2D cine DENSE studies have used a ke of 0.10 cycles/mm, which is high enough to remove an artifact-generating echo from k-space, provide high sensitivity to tissue displacements, and dephase the blood pool. However, through-plane dephasing can remove the unwanted echo and dephase the blood pool without relying on high ke. Additionally, the high sensitivity comes with the costs of increased phase wrapping and intra-voxel dephasing. We hypothesized that ke below 0.10 cycles/mm can be used to improve image characteristics and provide accurate measures of cardiac mechanics. Methods Spiral cine DENSE images were obtained for 10 healthy subjects and 10 patients with a history of heart disease on a 3 T Siemens Trio. A mid-ventricular short-axis image was acquired with different ke: 0.02, 0.04, 0.06, 0.08, and 0.10 cycles/mm. Peak twist, circumferential strain, and radial strain were compared between acquisitions employing different ke using Bland-Altman analyses and coefficients of variation. The percentage of wrapped pixels in the phase images at end-systole was calculated for each ke. The dephasing of the blood signal and signal to noise ratio (SNR) were also calculated and compared. Results Negligible differences were seen in strains and twist for all ke between 0.04 and 0.10 cycles/mm. These differences were of the same magnitude as inter-test differences. Specifically, the acquisitions with 0.04 cycles/mm accurately quantified cardiac mechanics and had zero phase wrapping. Compared to 0.10 cycles/mm, the acquisitions with 0.04 cycles/mm had 9 % greater SNR and negligible differences in blood pool dephasing. Conclusions For 2D cine DENSE with through-plane dephasing, the encoding frequency can be lowered to 0.04 cycles/mm without compromising the quantification of twist or strain. The amount of wrapping can be reduced with this lower value to greatly simplify the input to unwrapping algorithms. The strain and twist results from studies using different encoding frequencies can be directly compared.

Background Smearing artifacts were observed and investigated in diffusion tensor imaging (DTI) studies of macaque monkeys on a clinical whole-body 3T scanner. Methods Four adult macaques were utilized to evaluate DTI artifacts. DTI images were acquired with a single-shot echo-planar imaging (EPI) sequence using a parallel imaging technique. Results The smearing artifacts observed on the diffusion-weighted images and fractional anisotropy maps were caused by the incomplete fat suppression due to the irregular macaque frontal skull geometry and anatomy. The artifact can be reduced substantially using a novel three-dimensional (3D) shimming procedure. Conclusion The smearing artifacts observed on diffusion weighted images and fractional anisotropy (FA) maps of macaque brains can be reduced substantially using a robust 3D shimming approach. The DTI protocol combined with the shimming procedure could be a robust approach to examine brain connectivity and white matter integrity of non-human primates using a conventional clinical setting.

This study was to investigate the effects of Rosa laevigata Michx. (RLM) extract on reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) in lens epithelial cells (LECs) cultured under high glucose. SRA01/04 cell models of diabetic cataract were established by high glucose culture, and these cells were administrated with RLM extract. Levels of ROS and MMP in SRA01/04 cells were detected with fluorescent probes. HO-1 expression level, Akt phosphorylation, and Nrf2 translocation were detected by Western blot. RLM treatment could exert protective effects on SRA01/04 cells under high glucose condition, decreasing the ROS production and elevating the MMP in these cells. Western blot analysis indicated that the expression level of HO-1 was significantly elevated in SRA01/04 cells after the RLM treatment. Moreover, when HO-1 was interfered with siRNA, the effects of RLM on the levels of ROS and MMP were diminished, indicating that HO-1 induction was necessary for the function of RLM. Furthermore, HO-1 inducing effects of RLM were mediated by the PI3K/Akt and Nrf2/ARE pathways. The effects would be abolished when either pathway was inhibited by pharmacological manipulation or siRNA silencing. RLM inhibits ROS production and elevates MMP, through the induction of HO-1 expression, in LECs under high glucose condition. The protective effects of RLM are mediated by the PI3K/Akt and Nrf2/ARE pathways. Our findings provide theoretic basis and experimental evidence for the application of RLM in the treatment of diabetic cataract.

Background: The segmental extent of late gadolinium enhancement imaged with cardiac magnetic resonance early after acute ST-segment elevation myocardial infarction (STEMI) has weak spatial correspondence with final infarct on follow-up, thus its prognostic value is uncertain. We hypothesized that

Background Infarct size assessed early after acute ST-segment elevation myocardial infarction (STEMI) can overestimate the true extent of infarction, limiting its usefulness as a prognostic biomarker. Myocardial strain derived from displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR) provides information on myocardial contractility with high precision and accuracy. We hypothesised that the prognostic value of peak circumferential strain is higher than infarct size. Methods In a prospective, single centre study, participants underwent 1·5T CMR 2 days and 6 months after myocardial infarction. The 5-SD technique was used to quantify late gadolinium enhancement (LGE) as proportion of left ventricular mass. Mid-left ventricular DENSE acquisitions were analysed using postprocessing software. During longer-term follow-up, major adverse cardiac events (MACE) were independently assessed by masked cardiologists. Participants provided written informed consent and ethics approval was given (reference 10/S0703/28). This study is registered with ClinicalTrials.gov, number NCT02072850. Findings 300 patients underwent CMR (mean age 58·6 years [SD 13·2], 237 men [79%], 118 anterior myocardial infarction [39%], 30 with diabetes [10%], 284 with normal flow [Thrombolysis in Myocardial Infarction grade 3] after percutaneous coronary intervention [95%]). 259 of these patients had DENSE acquired, of whom 21 (8%) experienced a MACE at 3 years' follow-up. DENSE and baseline LGE had reasonable power for prediction of adverse events (area under the curve [AUC] DENSE 0·712, p=0·001; AUC LGE 0·644, p=0·028). For MACE (receiver operating characteristic analysis), optimal cut-offs for peak circumferential strain using DENSE was −10·51%, and LGE 24·05 g. Cox-regression analysis showed that DENSE (hazard ratio 1·175, 95% CI 0·036–1·334; p=0·012) offered an incremental prognostic benefit over LGE (1·040, 1·010–1·070; p=0·008) to predict MACE. Interpretation DENSE-derived peak circumferential strain offers an incremental prognostic benefit over infarct size revealed by LGE to predict MACE; a cut-off of −10·51% can identify STEMI patients at higher risk of events. This is the first time, to our knowledge, that CMR-derived strain has been shown to provide prognostic utility in patients with STEMI. Funding This research was supported by project grants from the Chief Scientist Office (SC01), Medical Research Scotland (343 FRG), and the British Heart Foundation (BHF-PG/14/64/31043).

Cerebrovascular diseases cause brain degeneration and subsequent decline of cognitive functions. In this study, comprehensive magnetic resonance imaging approaches with both structural and blood flow imaging were used to characterize the white matter hyperintensity in the brain, cerebral blood flow, and obstruction of vertebral artery caused by stenosis in various cases of individuals with cerebral vascular and cardiovascular risks. It is demonstrated that vertebral artery stenosis characterized as vertebral artery narrowing and/or reduced blood flow velocity by MRI may be associated with the regional specific cerebral vascular comorbidities detected as white matter hyperintensity and reduction of cerebral blood flow. More specifically, unilateral vertebral artery stenosis led to asymmetric periventricular WMHs, while bilateral vertebral artery with lower blood flow led to symmetric periventricular WMHs. The comprehensive MRI protocol with functional and high resolution structural imaging sequences is capable of providing valuable information on blood flow supply in the vertebral artery and cerebrovascular ischemia in individuals having vertebral and cardiovascular abnormalities.

Background The most time consuming and limiting step in three dimensional (3D) cine displacement encoding with stimulated echoes (DENSE) MR image analysis is the demarcation of the left ventricle (LV) from its surrounding anatomical structures. The aim of this study is to implement a semi-automated segmentation algorithm for 3D cine DENSE CMR using a guide point model approach. Methods A 3D mathematical model is fitted to guide points which were interactively placed along the LV borders at a single time frame. An algorithm is presented to robustly propagate LV epicardial and endocardial surfaces of the model using the displacement information encoded in the phase images of DENSE data. The accuracy, precision and efficiency of the algorithm are tested. Results The model-defined contours show good accuracy when compared to the corresponding manually defined contours as similarity coefficients Dice and Jaccard consist of values above 0.7, while false positive and false negative measures show low percentage values. This is based on a measure of segmentation error on intra- and inter-observer spatial overlap variability. The segmentation algorithm offers a 10-fold reduction in the time required to identify LV epicardial and endocardial borders for a single 3D DENSE data set. Conclusion A semi-automated segmentation method has been developed for 3D cine DENSE CMR. The algorithm allows for contouring of the first cardiac frame where blood-myocardium contrast is almost nonexistent and reduces the time required to segment a 3D DENSE data set significantly.

Background The functional impairment caused by peripheral arterial disease (PAD) is difficult to evaluate objectively and quantitatively. Current methods used to assess the efficacy of therapeutic interventions in patients with PAD are limited by variability and changes representing the placebo effect. Recently, Gadolinium-enhanced first-pass (FP) MRI has emerged as a new method to assess perfusion in peripheral muscles at peak exercise. We seek to demonstrate that calf muscle perfusion index measured with FP MRI at peak exercise correlates with treadmill exercise measures of ischemia in patients with PAD.

Background Mechanical properties of the aortic wall have been used to diagnose and characterize cardiovascular disease. Aortic stiffness correlates with aortic disease and disease progression. Mechanical regulation from strain and wall shear stress is hypothesized to influence remodeling in the cardiovascular system. Current non-invasive techniques for assessing aortic deformation are based on diameter changes, and are sensitive to through-plane motion of the aorta. Conventional methods for assessing strain, such as tagging, have limited resolution. We propose a new MRI approach that measures the regional stretch of the aortic wall itself using displacement encoding with stimulated echoes (DENSE). Methods Six subjects were studied with standard CINE and DENSE imaging of the tubular portion of the ascending aorta. DENSE was performed at the point of max dilation according to the cine images. The aorta was segmented in the DENSE images and the stretch of the aortic wall was calculated. Results Two young volunteers (26 years old) had an aortic stretch of 12%, two older patients (48 years old) with cardiovascular risk factors had stretch of 5%, and two older patients (60 years old) with dilated aortas had stretch of 1%. Figure 1 shows the circumferential stretch of 10±7% in a young volunteer (a), 5±6% in an older patient with aortic valve disease (b), and 0.4±0.4% in an older patient with a dilated aorta (c). Regional differences in stretch are noted with higher stretch seen on the right for the volunteer and the patient with valvular disease. Conclusions This novel application of DENSE imaging allows for direct assessment of regional stretch in the ascending

Within cardiomyocytes, endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) are thought to modulate L-type calcium channel (LTCC) function and sarcoplasmic reticulum calcium cycling, respectively. However, divergent results from mostly invasive prior studies suggest more complex roles. To elucidate the roles of nNOS and eNOS in vivo, we applied noninvasive cardiac MRI to study wild-type (WT), eNOS−/−, and nNOS−/− mice. An in vivo index of LTCC flux (LTCCI) was measured at baseline (Bsl), dobutamine (Dob), and dobutamine + carbacholamine (Dob + CCh) using manganese-enhanced MRI. Displacement-encoded MRI assessed contractile function by measuring circumferential strain (Ecc) and systolic (dEcc/dt) and diastolic (dEcc/dtdiastolic) strain rates at Bsl, Dob, and Dob + CCh. Bsl LTCCI was highest in nNOS−/− mice ( P < 0.05 vs. WT and eNOS−/−) and increased only in WT and eNOS−/− mice with Dob ( P < 0.05 vs. Bsl). LTCCI decreased significantly from Dob levels with Dob + CCh in all mice. Contractile function, as assessed by Ecc, was similar in all mice at Bsl. With Dob, Ecc increased significantly in WT and eNOS−/− but not nNOS−/− mice ( P < 0.05 vs. WT and eNOS−/−). With Dob + CCh, Ecc returned to baseline levels in all mice. Systolic blood pressure, measured via tail plethysmography, was highest in eNOS−/− mice ( P < 0.05 vs. WT and nNOS−/−). Mice deficient in nNOS demonstrate increased Bsl LTCC function and an attenuated contractile reserve to Dob, whereas eNOS−/− mice demonstrate normal LTCC and contractile function under all conditions. These results suggest that nNOS, not eNOS, plays the dominant role in modulating Ca2+ cycling in the heart.

Background Quantitative noninvasive imaging of myocardial mechanics in mice enables studies of the roles of individual genes in cardiac function. We sought to develop comprehensive three-dimensional methods for imaging myocardial mechanics in mice. Methods A 3D cine DENSE pulse sequence was implemented on a 7T small-bore scanner. The sequence used three-point phase cycling for artifact suppression and a stack-of-spirals k-space trajectory for efficient data acquisition. A semi-automatic 2D method was adapted for 3D image segmentation, and automated 3D methods to calculate strain, twist, and torsion were employed. A scan protocol that covered the majority of the left ventricle in a scan time of less than 25 minutes was developed, and seven healthy C57Bl/6 mice were studied. Results Using these methods, multiphase normal and shear strains were measured, as were myocardial twist and torsion. Peak end-systolic values for the normal strains at the mid-ventricular level were 0.29 ± 0.17, -0.13 ± 0.03, and -0.18 ± 0.14 for E rr , E cc , and E ll , respectively. Peak end-systolic values for the shear strains were 0.00 ± 0.08, 0.04 ± 0.12, and 0.03 ± 0.07 for E rc , E rl , and E cl , respectively. The peak end-systolic normalized torsion was 5.6 ± 0.9°. Conclusions Using a 3D cine DENSE sequence tailored for cardiac imaging in mice at 7 T, a comprehensive assessment of 3D myocardial mechanics can be achieved with a scan time of less than 25 minutes and an image analysis time of approximately 1 hour.

MRI of myocardial mechanics in mice enables the investigation of the roles of individual genes and experimental therapies in cardiac function. While two-dimensional tagging, HARP, and DENSE have previously been demonstrated for the mouse heart, myocardial mechanics are more comprehensively assessed using three-dimensional (3D) methods.

To obtain positive contrast based on T₁ weighting from magnetic iron oxide nanoparticle (IONP) using ultrashort echo time (UTE) imaging and investigate quantitative relationship between positive contrast and the core size and concentration of IONPs.Solutions of IONPs with different core sizes and concentrations were prepared. T₁ and T₂ relaxation times of IONPs were measured using the inversion recovery turbo spin echo (TSE) and multi-echo spin echo sequences at 3 Tesla. T₁ -weighted UTE gradient echo and T₂-weighted TSE sequences were used to image IONP samples. U87MG glioblastoma cells bound with arginine-glycine-aspartic acid (RGD) peptide and IONP conjugates were scanned using UTE, T₁ and T₂-weighted sequences.Positive contrast was obtained by UTE imaging from IONPs with different core sizes and concentrations. The relative-contrast-to-water ratio of UTE images was three to four times higher than those of T₂-weighted TSE images. The signal intensity increases as the function of the core size and concentration. Positive contrast was also evident in cell samples bound with RGD-IONPs.UTE imaging allows for imaging of IONPs and IONP bound tumor cells with positive contrast and provides contrast enhancement and potential quantification of IONPs in molecular imaging applications.

A navigator-gated 3D spiral cine displacement encoding with stimulated echoes (DENSE) pulse sequence for imaging 3D myocardial mechanics was developed. In addition, previously described 2D postprocessing algorithms including phase unwrapping, tissue tracking, and strain tensor calculation for the left ventricle (LV) were extended to 3D. These 3D methods were evaluated in five healthy volunteers, using 2D cine DENSE and historical 3D myocardial tagging as reference standards. With an average scan time of 20.5 ± 5.7 min, 3D data sets with a matrix size of 128 × 128 × 22, voxel size of 2.8 × 2.8 × 5.0 mm(3), and temporal resolution of 32 msec were obtained with displacement encoding in three orthogonal directions. Mean values for end-systolic mid-ventricular mid-wall radial, circumferential, and longitudinal strain were 0.33 ± 0.10, -0.17 ± 0.02, and -0.16 ± 0.02, respectively. Transmural strain gradients were detected in the radial and circumferential directions, reflecting high spatial resolution. Good agreement by linear correlation and Bland-Altman analysis was achieved when comparing normal strains measured by 2D and 3D cine DENSE. Also, the 3D strains, twist, and torsion results obtained by 3D cine DENSE were in good agreement with historical values measured by 3D myocardial tagging.