Magnetic Resonance Tracking Research Articles

Understanding the rheological properties from linear to nonlinear regimes and spatiotemporal structure of mixed kappa and reduced molecular weight lambda carrageenan gels

Blends of different carrageenan types have proven to be useful in tuning carrageenan gels' rheological properties. However, understanding the influence of a reduced molecular weight on the gelation of mixed carrageenan gels is still limited. Here, the gelation of mixed kappa-(KC) and reduced molecular weight lambda-(LC) carrageenan systems at different mixing ratios was evaluated using rheology from linear to nonlinear regimes via large amplitude oscillatory shear (LAOS), small-angle X-ray scattering (SAXS), pulsed nuclear magnetic resonance (NMR) and particle tracking. A single-step increase in moduli was seen for mixed kappa-lambda carrageenan (KCLC) gels with decreasing temperature while LC demonstrated nongelling behavior. The LAOS response of KCLC mixed gels showed the characteristic signature of strain-stiffening corresponding to the difference in the size and dynamics of the aggregates. The cross-sectional size revealed by SAXS and dynamics of the aggregates revealed by pulsed-NMR demonstrate that KCLC gels has higher segmental mobility and formed small aggregates that reduce with decreasing the KC fraction whereas pure KC gels formed large and rigid aggregates. Thus, the spatiotemporal features of the aggregates are considered to be the origin of the strain-stiffening in mixed gels under large deformation. Moreover, the microscopic properties of the KCLC gels evaluated using particle tracking revealed a homogenous network suggesting the formation of a swollen KC network in the LC solution. Hence, our findings provide insights into the rheological behavior and network structure design of KC and reduced molecular weight LC mixed gels.

Stereotactic Magnetic Resonance–guided Adaptive Radiation Therapy for Localized Kidney Cancer: Early Outcomes from a Prospective Phase 1 Trial and Supplemental Cohort

Stereotactic magnetic resonance (MR)-guided adaptive radiotherapy (SMART) for renal cell carcinoma may result in more precise treatment delivery through the capabilities for improved image quality, daily adaptive planning, and accounting for respiratory motion during treatment with real-time MR tracking. In this study, we aimed to characterize the safety and feasibility of SMART for localized kidney cancer. Twenty patients with localized kidney cancer (ten treated in a prospective phase 1 trial and ten in the supplemental cohort) were treated to 40 Gy in five fractions on a 0.35 T MR-guided linear accelerator with daily adaptive planning and a cine MR-guided inspiratory breath hold technique. The median follow-up time was 17 mo (interquartile range: 13–20 months). A single patient developed local failure at 30 mo. No grade ≥3 adverse events were reported. The mean decrease in estimated glomerular filtration rate was –1.8 ml/min/1.73 m2 (95% confidence interval or CI [–6.6 to 3.1 ml/min/1.73 m2]), and the mean decrease in tumor diameter was –0.20 cm (95% CI [–0.6 to 0.2 cm]) at the last follow-up. Anterior location and overlap of the 25 or 28 Gy isodose line with gastrointestinal organs at risk were predictive of the benefit from online adaptive planning. Kidney SMART is feasible and, at the early time point evaluated in this study, was well tolerated with minimal decline in renal function. More studies are warranted to further evaluate the safety and efficacy of this technique. Patient summaryFor patients with localized renal cell carcinoma who are not surgical candidates, stereotactic magnetic resonance-–guided adaptive radiotherapy is a feasible and safe noninvasive treatment option that results in minimal impact on kidney function.

Is myocardial fibrosis in patients with non-ischemic dilated cardiomyopathy associated with the whole-heart myocardial mechanics?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Non-ischemic dilated cardiomyopathy (NIDCM) is a severe form of primary myocardial disease related with progressive heart failure (HF) and a poor prognosis. In patients with NIDCM, myocardial fibrosis (MF) is associated to adverse cardiovascular outcomes and should be evaluated quickly in each case of NIDCM [1,2]. Purpose To evaluate the relationships between the whole-heart myocardial strain parameters and presence of late gadolinium enhancement (LGE) in a prospective cohort of NIDCM patients. Methods The study group consisted of 101 patients with NIDCM who were referred for a cardiovascular magnetic resonance (CMR) and speckle tracking echocardiography examination. We analyzed MF by LGE, and the whole-heart (both ventricles and atria) myocardial mechanics were evaluated by speckle tracking. All patients underwent a comprehensive clinical evaluation, laboratory test assessment, electrocardiogram, Holter monitoring. The exclusion criteria were ischemic coronary disease, primary valvular heart disease, chronic kidney disease (eGFR <30 ml/min/1.73 m2), under the age of 18, a poor echocardiographic or CMR image quality, inflammatory myocardial disease, previous pulmonary embolism, peripartum cardiomyopathy and toxic damage. Results The study group was divided into two groups according to the presence of MF fibrosis. The presence of MF was associated to worse of the whole-heart myocardial strain parameters. Both ventricles or atria were more dilated in the group with MF. The strongest relationships were detected between presence of MF and mechanical strain parameters of the left side of the heart (left ventricle ejection fraction (LVEF) (r=0.662, 25 p<0.001), left ventricle global circumferential strain (LV GCS) (r=-0.609, p<0.001), left ventricle global longitudinal strain (LV GLS) (r=-0.586, p<0.001), left atrial reservoir strain (LASr) (r=0.588, p<0.001). Logistic regression analysis revealed that the last three mentioned strain parameters were independently associated with presence of MF. Conclusions In patients with NIDCM, the whole-heart myocardial mechanics are worse in patients‘ presence of MF. LV GLS, LV GCS, and LARs are the best 2D echocardiographic mechanical strain parameters to prognosticate the presence of MF.

Late Gadolinium Enhancement by Cardiac Magnetic Resonance and Speckle Tracking Echocardiography in the Evaluation of Cardiac Complications in Chagas Cardiomyopathy: A Systematic Review

Late Gadolinium Enhancement by Cardiac Magnetic Resonance and Speckle Tracking Echocardiography in the Evaluation of Cardiac Complications in Chagas Cardiomyopathy: A Systematic Review

Tracking the Process of Domino Ring‐Opening and Coupling of Fused Imidazole and Direct Observation of Peroxide Intermediates

Comprehensive SummaryA domino ring‐opening and coupling of imidazolyl annulated heterocycles 1 (1a: 4‐methyl‐1‐(1‐methyl‐1H‐benzo[d]imidazol‐2‐yl)‐4H‐ benzo[d]imidazo[1,5‐a]imidazole, 1b: 1‐(1,5‐dimethyl‐1H‐benzo[d]imidazol‐2‐yl)‐4,7‐dimethyl‐4H‐benzo[d]imidazo[1,5‐a]imidazole) with dioxygen was developed at solvothermal condition, leading to conjugated 1,2‐diamidoalkenes derivatives 2 ((E)‐ArCONHArC=CArNHCOAr (Ar: 1‐methyl‐1H‐benzo[d]imidazolyl (2a), 1,5‐dimethyl‐1H‐benzo[d]imidazolyl (2b))) as single crystals directly. The reaction process was tracked by electrospray ionization mass spectrometry (ESI‐HRMS) and a series of reaction intermediates are detected. 18O2 labeling experiment verified the source of oxygen in 2. Combining evidence from control experiments, nuclear magnetic resonance (NMR) tracking, and crystallography, a seven‐step reaction pathway involving oxygen addition, ring opening, Friedel‐Crafts alkylation, oxidation, and dehydration was proposed and further supported by DFT calculation.

Cardiac magnetic resonance (CMR) versus Echo-doppler cardio graphic parameters for myocardial recovery Detection after chronic total occlusion (CTO) revascularization

Background and aim : Despite significant advances in the treatment of coronary artery disease (CAD), the condition remains the primary cause of morbidity and death globally. 15–20% of individuals with coronary artery disease (CAD) have chronic complete occlusion (CTO) of a coronary artery. The purpose of this study was to examine the usefulness of cardiac MR, TTE, Doppler Echocardiography, and speckle tracking echocardiography in identifying recovery in patients with CTO who benefited from revascularization following successful revascularization. Patients and Methods : Thirty patients with ischemic heart disease and coronary angiography-confirmed chronic complete blockage were included in this prospective, single-center observational research. Patients were exposed to a comprehensive history, current medicines, the angioplasty operation, echocardiography, two-dimensional echocardiography, myocardial strain evaluation, cardiovascular magnetic resonance imaging, and follow-up four months following PCI. Only GLS demonstrated a statistically significant improvement in myocardial recovery performance. Conclusion : CTO-PCI may successfully enhance LV function, as concluded.

Abstract TP241: Therapeutic Effects Of Magnet-induced Stem Cells Using Ferrimagnetic Iron Oxide Nanoparticles In Ischemic Stroke Model

Background: The efficiency of targeted delivery of stem cells via transplantation by intravenous injection is limited because of rapid clearance. Thus, more effective, newer methods are required. We hypothesized that combining the use of ferrimagnetic iron oxide nanoparticles (FION) labeling and magnetic fields could enhance the targeted delivery of stem cells after ischemic stroke. Methods: In a typical synthesis of FION nanocubes, iron(III) acetylacetonate was added to a mixture of oleic acid, 4-biphenylcarboxylic acid, and benzyl ether. Therapeutic effects of neural stem cells (NSC) using the magnetic nanoparticles in the cerebral ischemic stroke. Transient middle cerebral artery occlusion (MCAO) was induced in SD-rats. Iron oxide nanoparticle-labeled NSCs were injected into the tail vein. Magnetic resonance tracking and confirming labeled stem cells with Prussian blue staining. Polypeptides derived from receptors for advanced glycation end products and pharmaceutical composition for preventing and treating cerebrovascular disease comprise the same. Results: In the F3-VEGF NSC cell, FION uptake was shown as immunofluorescence. After overexpression of VEGF in F3 cells, it was confirmed by Western blotting. The measurements of cytotoxicity in FION's NSC showed toxicity over 80g but 40g was treated for 7 days and was not toxic. Six hours after MCAO induction, 4x10 6 NSCs were injected, and a magnet hat so that the stem cells implanted in the pathogen could move well. After one day, a behavioral test was conducted every week for up to 35 days. After MCAO induction, the group transplanted with FION-NSCs significantly improved in the behavioral test on Day 35 compared to the control group. In order to measure the distribution of FION in tissue, MRI was performed showing penetrating into the lesions of the white circles. As a result of ICP-MS, the magnet-applioed group was concentrated with FION 7 times more compared with the FION-only group. The distribution in brain tissue was observed through FION's Fluorescence images. Conclusions: Our study suggests that this use of a magnetic field may be useful for improving the efficacy of targeted migration of stem cells in stem-based cell therapy in ischemic brain injury.

Association of Whole-Heart Myocardial Mechanics by Transthoracic Echocardiography with Presence of Late Gadolinium Enhancement by CMR in Non-Ischemic Dilated Cardiomyopathy.

In patients with non-ischemic dilated cardiomyopathy (NIDCM), myocardial fibrosis (MF) is related to adverse cardiovascular outcomes. The purpose of this study was to evaluate the potential relationship between the myocardial mechanics of different chambers of the heart and the presence of MF and to determine the accuracy of the whole-heart myocardial strain parameters to predict MF in patients with NIDCM. We studied 101 patients (64% male; 50 ± 11 years) with a first-time diagnosis of NIDCM who were referred for a clinical cardiovascular magnetic resonance (CMR) and speckle tracking 2D echocardiography examination. We analyzed MF by late gadolinium enhancement (LGE), and the whole-heart myocardial mechanics were assessed by speckle tracking. The presence of MF was related to worse strain parameters in both ventricles and atria. The strongest correlations were found between MF and left ventricle (LV) global longitudinal strain (GLS) (r = -0.586, p < 0.001), global circumferential strain (GCS) (r = -0.609, p < 0.001), LV ejection fraction (LVEF) (r = 0.662, p < 0.001), and left atrial strain during the reservoir phase (LASr) (r = 0.588, p < 0.001). However, the binary logistic regression analysis revealed that only LV GLS, GCS, and LASr were independently associated with the presence of MF (area under the curves of 0.84, 0.85, and 0.64, respectively). None of the echocardiographic parameters correlated with fibrosis localization. In NIDCM patients, MF is correlated with reduced mechanical parameters in both ventricles and atria. LV GLS, LASr, and LV GCS are the most accurate 2D echocardiography predictive factors for the presence of MF.

Late Gadolinium Enhancement by Cardiac Magnetic Resonance and Speckle Tracking Echocardiography in the Evaluation of Cardiac Complications in Chagas Cardiomyopathy: A Systematic Review.

Chagas cardiomyopathy (CC) increases cardiovascular mortality associated with congestive heart failure (CHF), ventricular arrhythmias (VA), and sudden cardiac death (SCD). Different imaging techniques have been tested to assess disease progression and cardiac risk in individuals with Chagas disease (ChD). In this systematic review, we evaluated the accuracy in detecting cardiac complications in CC patients using cardiac magnetic resonance (CMR) and speckle tracking echocardiography (STE). A search was done on PubMed, Cochrane, and Embase for studies in humans over 18 years of age with ChD. Demographic data, research methodology, imaging parameters, and cardiac outcomes were extracted, and study quality was assessed, resulting in a narrative description. Twelve studies with 1124 patients were analyzed. One study discovered a contractility pattern by STE. Four studies assessed the identification of Early Cardiac Impairment (ECI) and VA risk, respectively, while three studies evaluated the risk of SCD. Global Longitudinal Strain (GLS) identified patients with ECI (-18.5 3.4% non-fibrosis vs -14.0 5.8% fibrosis, p = 0.006 and -18 2% non-fibrosis vs -15 2% fibrosis, p = 0.004). The amount of fibrosis 11.78% or in two or more contiguous transmural segments were markers for VA risk. GLS and the amount of fibrosis were found to be predictors of SCD. STE may be considered a screening technique for identifying the subclinical status of CHF. CMR using Late Gadolinium Enhancement (LGE) is considered a relevant parameter for stratifying patients with ChD who are at risk of SCD. Fibrosis and GLS can be used as markers to categorize patients at risk for arrhythmias.

Magnetic resonance tracking of copper ion fixation on the surface of carboxylated nanodiamonds from viewpoint of changes in carbon-inherited paramagnetism

Detonation nanodiamonds with a particle size of 5 nm and a carboxylated surface are easily modified by doubly charged copper ions to form copper chelate complexes. The concentration of copper complexes in a dry powder of such nanodiamonds is well monitored by the method of electron paramagnetic resonance, both by the signal width of intrinsic paramagnetic centers in nanodiamonds and by the signal shape for the surface Cu2+ ions themselves, including the set of hyperfine splitting lines for the parallel component and the line with an unresolved hyperfine structure for the perpendicular component.

Real-time MR tracking of AAV gene therapy with βgal-responsive MR probe in a murine model of GM1-gangliosidosis

Transformative results of adeno-associated virus (AAV) gene therapy in patients with spinal muscular atrophy and Leber’s congenital amaurosis led to approval of the first two AAV products in the United States to treat these diseases. These extraordinary results led to a dramatic increase in the number and type of AAV gene-therapy programs. However, the field lacks non-invasive means to assess levels and duration of therapeutic protein function in patients. Here, we describe a new magnetic resonance imaging (MRI) technology for real-time reporting of gene-therapy products in the living animal in the form of an MRI probe that is activated in the presence of therapeutic protein expression. For the first time, we show reliable tracking of enzyme expression after a now in-human clinical trial AAV gene therapy (ClinicalTrials.gov: NTC03952637) encoding lysosomal acid beta-galactosidase (βgal) using a self-immolative βgal-responsive MRI probe. MRI enhancement in AAV-treated enzyme-deficient mice (GLB-1−/−) correlates with βgal activity in central nervous system and peripheral organs after intracranial or intravenous AAV gene therapy, respectively. With >1,800 gene therapies in phase I/II clinical trials (ClinicalTrials.gov), development of a non-invasive method to track gene expression over time in patients is crucial to the future of the gene-therapy field.

Left atrial fibrosis: an essential hallmark in chronic mitral regurgitation

Abstract Chronic mitral regurgitation (MR) is the second valvular heart disease for incidence, which worsening severity gradually affects all cardiac chambers and leads to poor outcome if untreated. The recent development of minimally invasive surgical techniques and percutaneous intervention has reduced the operative risk, allowing a more confident referral of these patients for intervention. Therefore, there is a growing need of reliable markers to select the best therapeutic strategies and to identify the optimal timing for intervention. Myocardial fibrosis (MF) gradually occurs as a result of left atrial and ventricular (LA and LV) remodeling due to MR pressure and volume overload. It has been identified as an index of clinical outcome and arrhythmic risk in patients with MR. Particularly, the assessment of LA fibrosis not only allows to define different MR etiology, but also was associated with prognosis and atrial fibrillation (AF) burden. Nowadays, noninvasive estimation of MF is possible through the use of advanced imaging modalities, particularly cardiac magnetic resonance and speckle tracking echocardiography. This review discusses the role of LA fibrosis as a diagnostic and prognostic marker in patients with MR and its quantification by noninvasive multimodality cardiac imaging.

2D-echocardiography vs cardiac MRI strain using deep learning: a prospective cohort study in patients with HER2-positive breast cancer undergoing trastuzumab

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): Promotiefonds Albert Schweitzer Hospital Background Subclinical cardiotoxicity due to trastuzumab could be recognized by repeated measurements of global longitudinal/radial strain (GLS/GRS) which could be performed with cardiac magnetic resonance (CMR) or two-dimensional speckle tracking echocardiography (2DE-ST). Although CMR is the gold standard for cardiac function evaluation, it is not used for cardiac monitoring. 2DE-ST might be a reasonable alternative. Purpose To study the predictive value of early 2DE-ST for left ventricular ejection fraction (LVEF) changes during trastuzumab for HER2-positive breast cancer. Methods HER2-positive breast cancer patients receiving trastuzumab, with or without anthracycline, underwent 2DE-ST at baseline and after 3 and 6 months (m) trastuzumab. Cardiac magnetic resonance (CMR) imaging (with ST) was performed at baseline and 6m. We studied the correlation between 2DE-ST- and CMR-derived GLS and GRS. We then associated baseline and 3m 2DE-ST with later CMR-LVEF, and with cardiotoxicity, defined as CMR-LVEF <45% and/or absolute decline >10% during trastuzumab. Results 47 patients were included. GLS measurements based on 2DE-ST and CMR showed weak correlation (Pearson’s r = 0.33; P = 0.041); GRS measurements were uncorrelated (r = 0.09; P = 0.979). 2DE-LVEF at baseline and 3m, and 2DE-STE-GLS at 3m were predictive of CMR-LVEF at 6m (Table 1). In contrast, the change in 2DE-ST-GLS at 3m was predictive of the change in CMR-LVEF at 6m, whereas the change in 2DE-LVEF was not. Importantly, the 11 patients (28%) who developed cardiotoxicity had larger 2DE-ST-GLS change at 3m than those who did not (median 5.2% versus 1.7%; odds ratio 1.81, 95% confidence interval 1.11–2.93; P = 0.016). Conclusion Although correlations between 2DE-ST and CMR are weak, ST-measurements appeared useful to improve the performance of 2DE in predicting LVEF changes after 6m of trastuzumab. Table 1 2DE CMR-LVEF after 6m TZT Mean difference (95% CI) Change in CMR-LVEF after 6m TZT Mean difference (95% CI) Cardiotoxicity OR (95% CI) Before TZT LVEF, % 0.85 (0.42, 1.27)* 0.32 (-0.16, 0.80) 0.88 (0.75, 1.02) ST-GLS, % -0.42 (-1.31, 0.46) -0.28 (-1.14, 0.58) 1.13 (0.87, 1.46) 3 Months TZT LVEF, % 0.59 (0.30, 0.88)* 0.29 (-0.04, 0.61) 0.85 (0.74, 0.98)* ST-GLS, % -1.14 (-2.07, -0.19)* -0.62 (-1.54, 0.30) 1.36 (0.94, 1.84) Change at 3 months TZT LVEF, % 0.30 (-0.11, -0.71) 0.21 (-0.19, 0.61) 0.90 (0.80, 1.01) ST-GLS, % -1.17 (-2.14, -0.20)* -1.10 (-2.02, -0.18)* 1.81 (1.11, 2.93)* * P-value <0.05

Dual-modal magnetic resonance and photoacoustic tracking and outcome of transplanted tendon stem cells in the rat rotator cuff injury model

Stem cells have been used to promote the repair of rotator cuff injury, but their fate after transplantation is not clear. Therefore, contrast agents with good biocompatibility for labeling cell and a reliable technique to track cell are necessary. Here, we developed a micron-sized PLGA/IO MPs to label tendon stem cells (TSCs) and demonstrated that PLGA/IO MPs were safe and efficient for long-term tracking of TSCs by using dual-modal MR and Photoacoustic (PA) imaging both in vitro and in rat rotator cuff injury. Moreover, TSCs improved the repair of injury and the therapeutic effect was not affected by PLGA/IO MPs labeling. We concluded that PLGA/IO particle was a promising dual-modal MR/PA contrast for noninvasive long-term stem cell tracking.

Design of a Percutaneous MRI-Guided Needle Robot With Soft Fluid-Driven Actuator

Percutaneous ablation is a standard therapy for most cases of hepatocellular carcinoma (HCC), which is a general type of primary liver cancer. Magnetic resonance imaging (MRI) offers high-contrast images of soft tissue to monitor the ablation procedure. However, the success of MRI-guided ablation still depends on precise intra-tumor probe placement and skin insertion positioning, both of which require highly experienced operators, and can induce inter-operator variability in ablation results. In this letter, we present a semi-automated robotic system for MRI-guided percutaneous needle procedures. The compact and lightweight design enables the direct fixture of robot on the patient body and simultaneous needle targeting at multiple locations with several robots. Accurate (0.89 ± 0.31 mm) needle navigation is achieved by incorporating soft fluid-driven actuators with feedback control and stiffness modulation capabilities. The 3D location of the needle guide is reconfirmed by wireless MR tracking coils. The performance of the robotic platform, such as stiffness, needle positioning accuracy and frequency response was experimentally evaluated. Negligible interference to MR imaging was also validated by an MR compatibility test.

Sonoporation-based labeling of mesenchymal stem cells with polymeric MRI contrast agents for live-cell tracking

Cell transplantation has the potential to improve repair of injured tissue function; however, it is not clear how transplanted cells participate in functional recovery. We have recently succeeded in tracking millions of transplanted living cells using a polymeric MRI contrast agent, which was delivered into monolayer-cultured cells through electroporation. However, when cells were labeled using a conventional electroporation method, only cells localized around the electrode were labeled. To improve the percentage of labeled cells and to be able to start with fewer cells, we focused on a homogeneous cell labeling system. In this study, we optimized the sonoporation of a suspension culture with microbubbles for labeling and MR tracking of mesenchymal stem cells (MSCs). When water was used as the transmission medium between the acoustic probe and cell suspension, microbubbles gently collapsed with minimal cell damage. Under this condition, the number of labeled MSCs was 25%, which is 3.3-fold greater than the number of MSCs labeled using the previous system, and the cell viability was maintained at approximately 80%. The MRI signal could be clearly observed for 2.0 × 106 MSCs. These results suggest that sonoporation can efficiently introduce the polymeric contrast agent into MSCs. We optimized the sonoporation of a suspension culture with microbubbles for labeling and MR tracking of mesenchymal stem cells (MSCs). When water was used as the transmission medium between the acoustic probe and cell suspension, microbubbles gently collapsed with minimal cell damage. Under this condition, the number of labeled MSCs was 25%, which is 3.3-fold greater than the number of MSCs labeled using the conventional electroporation system, and the cell viability was maintained at approximately 80%. The MRI signal could be clearly observed for 2.0 × 106 MSCs.

Echocardiography and cardiovascular magnetic resonance based evaluation of myocardial strain and relationship with late gadolinium enhancement

ObjectivesWe sought to: (1) determine the agreement in cardiovascular magnetic resonance (CMR) and speckle tracking echocardiography (STE) derived strain measurements, (2) compare their reproducibility, (3) determine which approach is best related to CMR late gadolinium enhancement (LGE).BackgroundWhile STE-derived strain is routinely used to assess left ventricular (LV) function, CMR strain measurements are not yet standardized. Strain can be measured using dedicated pulse sequences (strain-encoding, SENC), or post-processing of cine images (feature tracking, FT). It is unclear whether these measurements are interchangeable, and whether strain can be used as an alternative to LGE.MethodsFifty patients underwent 2D echocardiography and 1.5 T CMR. Global longitudinal strain (GLS) was measured by STE (Epsilon), FT (NeoSoft) and SENC (Myocardial Solutions) and circumferential strain (GCS) by FT and SENC.ResultsGLS showed good inter-modality agreement (r-values: 0.71–0.75), small biases (< 1%) but considerable limits of agreement (− 7 to 8%). The agreement between the CMR techniques was better for GLS than GCS (r = 0.81 vs 0.67; smaller bias). Repeated measurements showed low intra- and inter-observer variability for both GLS and GCS (intraclass correlations 0.86–0.99; coefficients of variation 3–13%). LGE was present in 22 (44%) of patients. Both SENC- and FT-derived GLS and GCS were associated with LGE, while STE-GLS was not. Irrespective of CMR technique, this association was stronger for GCS (AUC 0.77–0.78) than GLS (AUC 0.67–0.72) and STE-GLS (AUC = 0.58).ConclusionThere is good inter-technique agreement in strain measurements, which were highly reproducible, irrespective of modality or analysis technique. GCS may better reflect the presence of underlying LGE than GLS.

Dual-modal magnetic resonance and photoacoustic tracking of tendon stem cell labeled with PLGA/IO MPs

Objective To detect the efficiency of the newly developed PLGA/IO MPs in tracking tendon stem cells (TSCs) by magnetic resonance (MR) and photoacoustic (PA) imaging. Methods Both PLAG/IO MPs and TSCs were prepared and acquired according to the previous study, and TSCs were incubated with PLGA/IO MPs for labeling.TSCs were collected for MR and PA imaging, prussian blue staining was performed, and the iron concentration of labeled TSCs was determined using inductively coupled plasma optical emission spectrometry (ICP-OES) at 3, 7, 14, 21 and 28 days after labeling respectively. The rotator cuff injury model was built on the right side of SD rats by surgery and the labeled TSCs were implanted instantly. Dual-modal MR/PA imaging was performed to observe the implanted labeled TSCs at day 3, 7, 14, 21 and 28 after implantation respectively. Results Along with the increase of labeling time, both MR and PA signal of labeled TSCs decreased gradually, and the amount of intracellular Fe loading was gradually decreased. At day 28, the difference of Fe concentration per cell between labeled TSCs and non-labeled TSCs was not significant (1.45 pg Fe/cell vs 1.17 pg Fe/cell, P>0.05). MR and PA imaging allowed a long-term tracking of labeled TSCs for 21 and 7 days respectively in the rat rotator cuff injury model. Conclusions PLGA/IO MPs are able to label TSCs for up to 21 days, and dual-modal MR/PA imaging could be used to track the labeled TSCs in the rat rotator cuff injury model. Key words: Tendon stem cells; Cell tracking; Magnetic resonance imaging; Photoacoustic imaging

Hybrid Decorated Core@Shell Janus Nanoparticles as a Flexible Platform for Targeted Multimodal Molecular Bioimaging of Cancer.

In the recent years, targeted cancer theranosis, the concomitant therapeutic treatment and selective visualization of cancerous tissue, has become a powerful strategy to improve patient prognosis. In this context, targeted multimodal molecular imaging, the combination of different imaging modalities overcoming their individual limitations, has attracted great attention. Due to their unique properties, advanced nanomaterials have taken center stage in the development of theranostics. In this work, we report a novel Janus nanoplatform by combining an Fe3O4 NPs/mesoporous silica core@shell face together with an Au nanoparticle face. Due to its anisotropy, this hybrid nanomaterial enabled the orthogonal site-selective modification of each face permitting the incorporation of a targeting peptide for cancer detection (cRGD) and a fluorescent dye. Due to the intrinsic characteristics of this Janus nanoplatform together with those selectively generated on their surfaces, the resulting hybrid nanocarrier successfully promoted the in vivo tumor-targeted multimodal imaging by magnetic resonance (Fe3O4 core), computed tomography (AuNP face), and fluorescent tracking (fluorescent dye loading) in a fibrosarcoma-bearing mouse model. The achieved results endorse these hybrid Janus nanoparticles as a powerful and flexible platform with integrated imaging and carrier functionalities to be equipped with therapeutic features to generate an advanced multifunctional nanocarrier for targeted cancer theranosis.

Compact Design of a Hydraulic Driving Robot for Intraoperative MRI-Guided Bilateral Stereotactic Neurosurgery

In this letter, we present an intraoperative magnetic resonance imaging (MRI)-guided robot for bilateral stereotactic procedures. Its compact design enables robot's operation within the constrained space of standard imaging head coil. magnetic resonance (MR) safe and high-performance hydraulic transmissions are incorporated. A maximum stiffness coefficient of 24.35 N/mm can be achieved with transmission fluid preloaded at 2 bar. Sufficient targeting accuracy (average within ≤1.73 mm) has been demonstrated in a simulated needle insertion task of deep brain stimulation. A novel MR-based wireless tracking technique is adopted. It is capable of offering real-time and continuous (30-40 Hz) three-dimensional (3-D) localization of robotic instrument under the proper MR tracking sequence. It outperforms the conventional method of using low-contrast passive fiducials that can only be revealed in the MR image domain. Two wireless tracking units/markers are integrated with the robot, which are two miniaturized coil circuits in size of 1.5 × 5 × 0.2 mm 3 , fabricated on flexible thin films. A navigation test was performed under the standard MRI settings in order to visualize the 3-D localization of the robotic instrument. MRI compatibility test was also carried out to prove the minimal interference to MR images of the presented hydraulic robotic platform.