Interlayer dural split technique for Chiari I malformation treatment in adult-Technical note.

OBJECTIVE: To present an alternative surgical technique in treating cases of Chiari I Malformation with mild-to-moderate syringomyelia after decompressive suboccipital craniectomy: incising only the outer layer of the dura mater, then dissecting it from the inner layer without opening the latter. PATIENTS AND METHODS: We utilized this technique in a short series of three cases who were admitted to our department for mild symptoms such as intermittent headache and dissociated sensory loss in the upper limbs, caused by a Chiari Malformation Type I. The patients were placed in the sitting position. We performed a reduced median suboccipital craniectomy and resection of the posterior arch of C1 adapted to the level of tonsil descent, from a limited superior half to complete resection. Afterward, we incised the outer dural layer, while sparing the inner one. Using a fine dissector, we then split apart the outer and inner layers to the margin of the craniectomy. Through the transparency of the inner layer and the arachnoid, the cerebellum and the medulla were visible and pulsating. An autologous fascia duraplasty was then performed. RESULTS: The postoperative course was favorable in all cases, the patients being discharged without any deficits and with complete symptom resolution. Follow-up at 3, 6, and 12 months after surgery revealed a significant reduction in brainstem compression and syringomyelia. CONCLUSIONS: Interlayer dural split technique can be used effectively in treating symptomatic cases of type I Chiari malformation in adults, with mild-to-moderate syringomyelia. It is less invasive than opening the dura and possibly more effective than decompressive craniectomy and C1 laminectomy alone. This technique must be validated in a larger case-control series.

Cardiac Amyloidosis with Discordant QRS Voltage between Frontal and Precordial Leads.

Among the different types, immunoglobulin light chain (AL) cardiac amyloidosis is associated with the highest morbidity and mortality. The outcome, however, is significantly better when an early diagnosis is made and treatment initiated promptly. We present a case of cardiac amyloidosis with left ventricular hypertrophy criteria on the electrocardiogram. After 9 months of follow-up, the patient developed low voltage in the limb leads, while still maintaining the Cornell criteria for left ventricular hypertrophy as well. The relative apical sparing by the disease process, as well as decreased cancellation of the opposing left ventricular walls could be responsible for this phenomenon. The discordance between the voltage in the frontal leads and precordial leads, when present in conjunction with other findings, may be helpful in raising the clinical suspicion of cardiac amyloidosis.

Multi-contrast volumetric imaging with isotropic resolution for assessing infarct heterogeneity: Initial clinical experience.

BACKGROUND: To evaluate accelerated multi-contrast volumetric imaging with isotropic resolution reconstructed using low-rank and spatially varying edge-preserving constrained compressed sensing parallel imaging reconstruction (CP-LASER), for assessing infarct heterogeneity on post-infarction patients as a precursor to studies of utility for predicting ventricular arrhythmias. METHODS: Eleven patients with prior myocardial infarction were included in the study. All subjects underwent cardiovascular magnetic resonance (CMR) scans including conventional two-dimensional late gadolinium enhancement (2D LGE) and three-dimensional multi-contrast late enhancement (3D MCLE) post-contrast. The extent of the infarct core and peri-infarct gray zone of a limited mid-ventricular slab were derived respectively by analyzing MCLE images with an isotropic resolution of 2.2 mm and an anisotropic resolution of 2.2×2.2×8.8 mm 3 , and LGE images with a resolution of 1.37×2.7×8 mm 3 ; the respective measures across all subjects were statistically compared. RESULTS: Using 3D MCLE, the infarct core size measured with isotropic resolution was similar to that measured with anisotropic resolution, while the peri-infarct gray zone size measured with isotropic resolution was smaller than that measured with anisotropic resolution ( p<0.001 , Cohen's dz=1.33 ). Isotropic 3D MCLE yielded a significantly smaller measure of the peri-infarct gray zone size than conventional 2D LGE ( p=0.0016 , Cohen's dz=1.20 ). Overall, we have successfully shown the utility of isotropic 3D MCLE in a pilot patient study. Our results suggest that smaller voxels lead to more accurate differentiation between isotropic 3D MCLE-derived gray zone and core infarct because of diminished partial volume effect. CONCLUSION: The CP-LASER accelerated 3D MCLE with isotropic resolution can be used in patients and yields excellent delineation of infarct and peri-infarct gray zone characteristics.

Ketoconazole-p-aminobenzoic Acid Cocrystal: Revival of an Old Drug by Crystal Engineering.

The 1:1 cocrystal of the antifungal agent ketoconazole with p-aminobenzoic acid was successfully crystallized and systematically characterized by a physical and pharmacological point of view. Crystal structure determination confirmed the cocrystal identity, giving full insight in its crystal packing and degree of disorder. Powder dissolution measurements revealed a 10-fold aqueous solubility increase that induces a 6.7-fold oral bioavailability improvement compared to ketoconazole. In vitro cell assays showed a good toxicity profile of the cocrystal with lower oxidative stress and inflammation and enhanced antifungal activity against several Candida species. The in vivo study of the cocrystal indicated similar pharmacokinetic profiles and liver toxicity with increased transaminases, as reported for ketoconazole. Notably, besides minor signs of inflammation, no morphological changes in liver parenchyma or signs of fibrosis and necrosis were detected. The enhanced solubility and oral bioavailability of the cocrystal over ketoconazole, together with the improved antifungal activity and good in vitro/in vivo toxicity, indicate its potential use as an alternative antifungal agent to the parent drug. Our results bring evidence of cocrystallization as a successful approach for bioavailability improvement of poorly soluble drugs.

Accelerated multicontrast volumetric imaging with isotropic resolution for improved peri-infarct characterization using parallel imaging, low-rank and spatially varying edge-preserving sparse modeling.

PURPOSE: To achieve consistent effectiveness in reconstruction of fine image features for cases of varying contrast-to-noise ratio (CNR) to facilitate translating accelerated multicontrast volumetric imaging with isotropic resolution toward clinical utility in peri-infarct characterization. THEORY AND METHODS: A low-rank and spatially varying edge-preserving constrained compressed sensing parallel imaging reconstruction method (CP-LASER) is developed to effectively preserve contrast of small-scale structures for highly accelerated multicontrast volumetric imaging in CNR-limited scenarios. CP-LASER synergistically integrates parallel imaging, low-rank and spatially varying edge-preserving sparse modeling to achieve high signal-to-noise-ratio efficiency by leveraging prior knowledge about signal properties including coil sensitivity weighting, spatiotemporally correlated signal relaxation, and spatially varying sparsity. RESULTS: In the preclinical study using highly accelerated multicontrast volumetric imaging with an isotropic 1.5-mm resolution, CP-LASER demonstrated robust multicontrast reconstruction of peri-infarct characteristics with excellent correspondence with histopathology. CP-LASER provides better delineation of the peri-infarct border zone with improved sharpness than alternative methods in a clinical demonstration on 1.5T with an isotropic 2.2-mm resolution achieved in a single breath-hold. CONCLUSION: Accelerated multicontrast volumetric imaging with isotropic resolution using CP-LASER has demonstrated the potential to improve peri-infarct characterization in a clinical setting. Magn Reson Med 79:3018-3031, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Cardiovascular magnetic resonance guided ablation and intra-procedural visualization of evolving radiofrequency lesions in the left ventricle.

BACKGROUND: Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution of acute left ventricular (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided ablation procedures. METHODS: RF ablation was performed using an actively-tracked CMR-enabled catheter guided into the LV of 12 healthy swine to create 14 RF ablation lesions. T2 maps were acquired immediately post-ablation to visualize myocardial edema at the ablation sites and T1-weighted inversion recovery prepared balanced steady-state free precession (IR-SSFP) imaging was used to visualize the lesions. These sequences were repeated concurrently to assess the physiological response following ablation for up to approximately 3 h. Multi-contrast late enhancement (MCLE) imaging was performed to confirm the final pattern of ablation, which was then validated using gross pathology and histology. RESULTS: Edema at the ablation site was detected in T2 maps acquired as early as 3 min post-ablation. Acute T2-derived edematous regions consistently encompassed the T1-derived lesions, and expanded significantly throughout the 3-h period post-ablation to 1.7 ± 0.2 times their baseline volumes (mean ± SE, estimated using a linear mixed model determined from n = 13 lesions). T1-derived lesions remained approximately stable in volume throughout the same time frame, decreasing to 0.9 ± 0.1 times the baseline volume (mean ± SE, estimated using a linear mixed model, n = 9 lesions). CONCLUSIONS: Combining native T1- and T2-based imaging showed that distinctive regions of ablation injury are reflected by these contrast mechanisms, and these regions evolve separately throughout the time period of an intervention. An integrated description of the T1-derived lesion and T2-derived edema provides a detailed picture of acute lesion composition that would be most clinically useful during an ablation case.

Multicontrast reconstruction using compressed sensing with low rank and spatially varying edge-preserving constraints for high-resolution MR characterization of myocardial infarction.

PURPOSE: To enable robust reconstruction for highly accelerated three-dimensional multicontrast late enhancement imaging to provide improved MR characterization of myocardial infarction with isotropic high spatial resolution. THEORY AND METHODS: A new method using compressed sensing with low rank and spatially varying edge-preserving constraints (CS-LASER) is proposed to improve the reconstruction of fine image details from highly undersampled data. CS-LASER leverages the low rank feature of the multicontrast volume series in MR relaxation and integrates spatially varying edge preservation into the explicit low rank constrained compressed sensing framework using weighted total variation. With an orthogonal temporal basis pre-estimated, a multiscale iterative reconstruction framework is proposed to enable the practice of CS-LASER with spatially varying weights of appropriate accuracy. RESULTS: In in vivo pig studies with both retrospective and prospective undersamplings, CS-LASER preserved fine image details better and presented tissue characteristics with a higher degree of consistency with histopathology, particularly in the peri-infarct region, than an alternative technique for different acceleration rates. An isotropic resolution of 1.5 mm was achieved in vivo within a single breath-hold using the proposed techniques. CONCLUSION: Accelerated three-dimensional multicontrast late enhancement with CS-LASER can achieve improved MR characterization of myocardial infarction with high spatial resolution. Magn Reson Med 78:598-610, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Real-time MRI guidance of cardiac interventions.

Cardiac magnetic resonance imaging (MRI) is appealing to guide complex cardiac procedures because it is ionizing radiation-free and offers flexible soft-tissue contrast. Interventional cardiac MR promises to improve existing procedures and enable new ones for complex arrhythmias, as well as congenital and structural heart disease. Guiding invasive procedures demands faster image acquisition, reconstruction and analysis, as well as intuitive intraprocedural display of imaging data. Standard cardiac MR techniques such as 3D anatomical imaging, cardiac function and flow, parameter mapping, and late-gadolinium enhancement can be used to gather valuable clinical data at various procedural stages. Rapid intraprocedural image analysis can extract and highlight critical information about interventional targets and outcomes. In some cases, real-time interactive imaging is used to provide a continuous stream of images displayed to interventionalists for dynamic device navigation. Alternatively, devices are navigated relative to a roadmap of major cardiac structures generated through fast segmentation and registration. Interventional devices can be visualized and tracked throughout a procedure with specialized imaging methods. In a clinical setting, advanced imaging must be integrated with other clinical tools and patient data. In order to perform these complex procedures, interventional cardiac MR relies on customized equipment, such as interactive imaging environments, in-room image display, audio communication, hemodynamic monitoring and recording systems, and electroanatomical mapping and ablation systems. Operating in this sophisticated environment requires coordination and planning. This review provides an overview of the imaging technology used in MRI-guided cardiac interventions. Specifically, this review outlines clinical targets, standard image acquisition and analysis tools, and the integration of these tools into clinical workflow. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2017;46:935-950.

Hemorrhage promotes inflammation and myocardial damage following acute myocardial infarction: insights from a novel preclinical model and cardiovascular magnetic resonance.

BACKGROUND: Myocardial hemorrhage is a frequent complication following reperfusion in acute myocardial infarction and is predictive of adverse outcomes. However, it remains unsettled whether hemorrhage is simply a marker of a severe initial ischemic insult or directly contributes to downstream myocardial damage. Our objective was to evaluate the contribution of hemorrhage towards inflammation, microvascular obstruction and infarct size in a novel porcine model of hemorrhagic myocardial infarction using cardiovascular magnetic resonance (CMR). METHODS: Myocardial hemorrhage was induced via direct intracoronary injection of collagenase in a novel porcine model of ischemic injury. Animals (N = 27) were subjected to coronary balloon occlusion followed by reperfusion and divided into three groups (N = 9/group): 8 min ischemia with collagenase (+HEM); 45 min infarction with saline (I-HEM); and 45 min infarction with collagenase (I+HEM). Comprehensive CMR was performed on a 3 T scanner at baseline and 24 h post-intervention. Cardiac function was quantified by cine imaging, edema/inflammation by T2 mapping, hemorrhage by T2* mapping and infarct/microvascular obstruction size by gadolinium enhancement. Animals were subsequently sacrificed and explanted hearts underwent histopathological assessment for ischemic damage and inflammation. RESULTS: At 24 h, the +HEM group induced only hemorrhage, the I-HEM group resulted in a non-hemorrhagic infarction, and the I+HEM group resulted in infarction and hemorrhage. Notably, the I+HEM group demonstrated greater hemorrhage and edema, larger infarct size and higher incidence of microvascular obstruction. Interestingly, hemorrhage alone (+HEM) also resulted in an observable inflammatory response, similar to that arising from a mild ischemic insult (I-HEM). CMR findings were in good agreement with histological staining patterns. CONCLUSIONS: Hemorrhage is not simply a bystander, but an active modulator of tissue response, including inflammation and microvascular and myocardial damage beyond the initial ischemic insult. A mechanistic understanding of the pathophysiology of reperfusion hemorrhage will potentially aid better management of high-risk patients who are prone to adverse long-term outcomes.

Assessment of the longitudinal changes in infarct heterogeneity post myocardial infarction.

BACKGROUND: Infarct heterogeneity, as assessed by determination of the peri-infarct zone (PIZ) by cardiac magnetic resonance imaging, has been shown to be an independent predictor for the development of cardiac arrhythmias and mortality post myocardial infarction (MI). The temporal evolution of the PIZ post MI is currently unknown. Thus, the main objective of our study was to describe the temporal evolution of the PIZ over a 6 month time period in contemporarily managed ST elevation myocardial infarction (STEMI) patients. Further, given the poor prognosis associated with microvascular obstruction (MVO) post STEMI, we sought to compare the temporal evolution of the PIZ in patients with and without MVO. We hypothesized that patients with MVO would show a relative persistence of PIZ over time when compared to those without MVO. METHODS: Twenty-one patients post primary percutaneous coronary intervention were enrolled and treated with evidence based therapy. Each patient had three cardiac MRI scans at 48 h, 3 weeks and 6 months post infarction. Repeated Measures Analysis of Variance (ANOVA) was used to assess the evolution of core infarct size and peri-infarct zone size across the three time frames. RESULTS: The patients in this study were predominantly male, with ~40 % LAD territory infarction and a mean LVEF of 46 ± 7 %. Core infarct size and PIZ size both decreased significantly across the three time frames. The presence of microvascular obstruction (MVO), a known adverse prognostic factor, influenced PIZ size. Both patients with and without MVO had a significant reduction in core infarct size over time. Patients with MVO did not have a significant change in PIZ size over time (11.9 ± 6.8 %, 12.2 ± 7.5 %, 10.7 ± 6.6 % p = 0.77). In contrast, non-MVO patients did have a significant decrease in PIZ size over time (7.0 ± 5.5 %, 7.1 ± 6.5 %, 2.7 ± 2.6 %, p = 0.01). CONCLUSIONS: Peri-infarct zone size, like core infarct size, varies depending upon the timing of measurement. Patients with MVO displayed a persistence of the PIZ over time.

Characterization of the ultrashort-TE (UTE) MR collagen signal.

Although current cardiovascular MR (CMR) techniques for the detection of myocardial fibrosis have shown promise, they nevertheless depend on gadolinium-based contrast agents and are not specific to collagen. In particular, the diagnosis of diffuse myocardial fibrosis, a precursor of heart failure, would benefit from a non-invasive imaging technique that can detect collagen directly. Such a method could potentially replace the need for endomyocardial biopsy, the gold standard for the diagnosis of the disease. The objective of this study was to measure the MR properties of collagen using ultrashort TE (UTE), a technique that can detect short T2* species. Experiments were performed in collagen solutions. Via a model of bi-exponential T2* with oscillation, a linear relationship (slope = 0.40 ± 0.01, R(2) = 0.99696) was determined between the UTE collagen signal fraction associated with these properties and the measured collagen concentration in solution. The UTE signal of protons in the collagen molecule was characterized as having a mean T2* of 0.75 ± 0.05 ms and a mean chemical shift of -3.56 ± 0.01 ppm relative to water at 7 T. The results indicated that collagen can be detected and quantified using UTE. A knowledge of the collagen signal properties could potentially be beneficial for the endogenous detection of myocardial fibrosis.

Distribution of abnormal potentials in chronic myocardial infarction using a real time magnetic resonance guided electrophysiology system.

BACKGROUND: Identification of viable slow conduction zones manifested by abnormal local potentials is integral to catheter ablation of ventricular tachycardia (VT) sites. The relationship between contrast patterns in cardiovascular magnetic resonance (CMR) and local electrical mapping is not well characterized. The purpose of this study was to identify regions of isolated, late and fractionated diastolic potentials in sinus rhythm and controlled-paced rhythm in post-infarct animals relative to regions detected by late gadolinium enhancement CMR (LGE-CMR). METHODS: Using a real-time MR-guided electrophysiology system, electrogram (EGM) recordings were used to generate endocardial electroanatomical maps in 6 animals. LGE-CMR was also performed and tissue classification (dense infarct, gray zone and healthy myocardium) was then correlated to locations of abnormal potentials. RESULTS: For abnormal potentials in sinus rhythm, relative occurrence was equivalent 24%, 27% and 22% in dense scar, gray zone and healthy tissue respectively (p = NS); in paced rhythm, the relative occurrence of abnormal potentials was found to be different with 30%, 42% and 21% in dense scar, gray zone and healthy myocardium respectively (p = 0.001). For location of potentials, in the paced case, the relative frequency of abnormal EGMs was 19.9%, 65.4% and 14.7% in the entry, central pathway and exit respectively (p = 0.05), putative regions being defined by activation times. CONCLUSIONS: Our data suggests that gray zone quantified by LGE-CMR exhibits abnormal potentials more frequently than in healthy tissue or dense infarct when right ventricular apex pacing is used.

MRI Accurately Visualizes RF Ablation Delivery Targeted to MRI-Defined Arrhythmia Substrates in the Left Ventricle.

OBJECTIVE: Investigate the capacity of MRI to evaluate efficacy of radiofrequency (RF) ablations delivered to MRI-defined arrhythmogenic substrates. METHODS: Baseline MRI was performed at 3T including 3D LGE in a swine model of chronic myocardial infarct (N=8). MRI-derived maps of scar and heterogeneous tissue channels (HTCs) were generated using ADAS 3D. Animals underwent electroanatomic mapping and ablation of the left ventricle in CARTO3, guided by MRI-derived scar maps. Post-ablation MRI (in vivo at 3T in 5/8 animals; ex vivo at 1.5T in 3/8) included 3D native T1-weighted IR-SPGR (TI=700-800ms) to visualize RF lesions. T1-derived RF lesions were compared against excised tissue. The locations of T1-derived RF lesions were compared against CARTO ablation tags, and segment-wise sensitivity and specificity of lesion detection were calculated within the AHA 17-segment model. RESULTS: RF lesions were clearly visualized in HTCs, scar, and myocardium. Ablation patterns delivered in CARTO matched T1-derived RF lesion patterns with high sensitivity (88.9%) and specificity (94.7%), and were closely matched in registered MR-EP data sets, with a displacement of 5.4 ±3.8mm (N=152 ablation tags). CONCLUSION: Integrating MRI into ablative procedures for RF lesion assessment is feasible. Patterns of RF lesions created using a standard 3D EAM system are accurately reflected by MRI visualization in healthy myocardium, scar, and HTCs comprising the MRI-defined arrhythmia substrate. SIGNIFICANCE: MRI visualization of RF lesions can provide near-immediate (<24h) assessment of ablation, potentially indicating whether critical MRI-defined ventricular tachycardia substrates have been adequately ablated.

Quantitative magnetic resonance imaging can distinguish remodeling mechanisms after acute myocardial infarction based on the severity of ischemic insult.

The type and extent of myocardial infarction encountered clinically is primarily determined by the severity of the initial ischemic insult. The purpose of the study was to differentiate longitudinal fluctuations in remodeling mechanisms in porcine myocardium following different ischemic insult durations. Animals (N = 8) were subjected to coronary balloon occlusion for either 90 or 45 min, followed by reperfusion. Imaging was performed on a 3 T MRI scanner between day-2 and week-6 postinfarction with edema quantified by T2, hemorrhage by T2*, vasodilatory function by blood-oxygenation-level-dependent T2 alterations and infarction/microvascular obstruction by contrast-enhanced imaging. The 90-min model produced large transmural infarcts with hemorrhage and microvascular obstruction, while the 45 min produced small nontransmural and nonhemorrhagic infarction. In the 90-min group, elevation of end-diastolic-volume, reduced cardiac function, persistence of edema, and prolonged vasodilatory dysfunction were all indicative of adverse remodeling; in contrast, the 45-min group showed no signs of adverse remodeling. The 45- and 90-min porcine models seem to be ideal for representing the low- and high-risk patient groups, respectively, commonly encountered in the clinic. Such in vivo characterization will be a key in predicting functional recovery and may potentially allow evaluation of novel therapies targeted to alleviate ischemic injury and prevent microvascular obstruction/hemorrhage.

Simultaneous data assimilation and cardiac electrophysiology model correction using differentiable physics and deep learning.

Modelling complex systems, like the human heart, has made great progress over the last decades. Patient-specific models, called 'digital twins', can aid in diagnosing arrhythmias and personalizing treatments. However, building highly accurate predictive heart models requires a delicate balance between mathematical complexity, parameterization from measurements and validation of predictions. Cardiac electrophysiology (EP) models range from complex biophysical models to simplified phenomenological models. Complex models are accurate but computationally intensive and challenging to parameterize, while simplified models are computationally efficient but less realistic. In this paper, we propose a hybrid approach by leveraging deep learning to complete a simplified cardiac model from data. Our novel framework has two components, decomposing the dynamics into a physics based and a data-driven term. This construction allows our framework to learn from data of different complexity, while simultaneously estimating model parameters. First, using in silico data, we demonstrate that this framework can reproduce the complex dynamics of cardiac transmembrane potential even in the presence of noise in the data. Second, using ex vivo optical data of action potentials (APs), we demonstrate that our framework can identify key physical parameters for anatomical zones with different electrical properties, as well as to reproduce the AP wave characteristics obtained from various pacing locations. Our physics-based data-driven approach may improve cardiac EP modelling by providing a robust biophysical tool for predictions.

Efficient Patient-Specific Simulations of Ventricular Tachycardia Based on Computed Tomography-Defined Wall Thickness Heterogeneity.

BACKGROUND: Electrophysiological mapping of ventricular tachycardia (VT) is tedious and poorly reproducible. Substrate analysis on imaging cannot explicitly display VT circuits. OBJECTIVES: This study sought to introduce a computed tomography-based model personalization approach, allowing for the simulation of postinfarction VT in a clinically compatible time frame. METHODS: In 10 patients (age 65 ± 11 years, 9 male) referred for post-VT ablation, computed tomography-derived wall thickness maps were registered to 25 electroanatomical maps (sinus rhythm, paced, and VT). The relationship between wall thickness and electrophysiological characteristics (activation-recovery interval) was analyzed. Wall thickness was then employed to parameterize a fast and tractable organ-scale wave propagation model. Pacing protocols were simulated from multiple sites to test VT induction in silico. In silico VTs were compared to VT circuits mapped clinically. RESULTS: Clinically, 6 different VTs could be induced with detailed maps in 9 patients. The proposed model allowed for fast simulation (median: 6 min/pacing site). Simulations of steady pacing (600 milliseconds) from 100 different sites/patient never triggered any arrhythmia. Applying S1-S2 or S1-S2-S3 induction schemes allowed for the induction of in silico VTs in the 9 of 10 patients who were clinically inducible. The patient who was not inducible clinically was also noninducible in silico. A total of 42 different VTs were simulated (4.2 ± 2 per patient). Six in silico VTs matched a VT circuit mapped clinically. CONCLUSIONS: The proposed framework allows for personalized simulations in a matter of hours. In 6 of 9 patients, simulations show re-entrant patterns matching intracardiac recordings.

Structure of the inclusion complex of ß-cyclodextrin with lipoic acid from laboratory powder diffraction data.

The crystal structure of the inclusion complex of ß-cyclodextrin with lipoic acid was determined from laboratory powder diffraction data. Thermogravimetric data was used to estimate the number of water molecules in the crystal structure. Lipoic acid is included in ß-cyclodextrin through its primary face with the five-membered ring reaching the center plane of the cyclodextrin cavity and its fatty acid chain adopting a bent conformation. Lipoic acid and ß-cyclodextrin form a channel-like packing which is stabilized by guest-host hydrogen bonding and close contacts, host-host intermolecular interactions and hydrogen bonding involving the water molecules.

N-Butyl-4-butyl-imino-2-methyl-pentan-2-aminium (E)-quercetinate.

The title salt, C(14)H(31)N(2) (+)·C(15)H(9)O(7) (-), was obtained in the reaction of quercetin with n-butyl-amine in a mixture of acetone and hexane. The crystal structure determination shows that the quercetin donates one of its phenol H atoms to the N-butyl-4-butyl-imino-2-methyl-pentan-2-amine mol-ecule. The crystal structure of the salt is stabilized by intramolecular (N-H⋯N for the cation and O-H⋯O for the anion) and intermolecular hydrogen bonding (N-H⋯O between cation-anion pairs and O-H⋯O between anions). Quercetin molecules form dimers connected into a two-dimensional network. The dihedral angle between the quercetin ring systems is 19.61 (8)°.

MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute Lesions and Associated Electrophysiologic Voltage Reductions.

OBJECTIVE: Radiofrequency (RF) energy delivered to cardiac tissue produces a core ablation lesion with surrounding edema, the latter of which has been implicated in acute procedural failure of Ventricular Tachycardia (VT) ablation and late arrhythmia recurrence. This study sought to investigate the electrophysiological characteristics of acute RF lesions in the left ventricle (LV) visualized with native-contrast Magnetic Resonance Imaging (MRI). METHODS: An MR-guided electrophysiology system was used to deliver RF ablation in the LV of 8 swine (9 RF lesions in total), then perform MRI and electroanatomic mapping. The permanent RF lesions and transient edema were delineated via native-contrast MRI segmentation of T1-weighted images and T2 maps respectively. Bipolar voltage measurements were matched with image characteristics of pixels adjacent to the catheter tip. Native-contrast MR visualization was verified with 3D late gadolinium enhanced MRI and histology. RESULTS: The T2-derived edema was significantly larger than the T1-derived RF lesion (2.1 ±1.5 mL compared to 0.58 ±0.34 mL; p=0.01). Bipolar voltage was significantly reduced in the presence of RF lesion core (p 0.05) and edema (p 0.05), with similar trends suggesting that both the permanent lesion and transient edema contributed to the region of reduced voltage. While bipolar voltage was significantly decreased where RF lesions are present (p 0.05), voltage did not change significantly with lesion transmurality (p 0.05). CONCLUSION: Permanent RF lesions and transient edema are distinct in native-contrast MR images, but not differentiable using bipolar voltage. SIGNIFICANCE: Intraprocedural native-contrast MRI may provide valuable lesion assessment in MR-guided ablation, whose clinical application is now feasible.

Myocardial BOLD imaging at 3 T using quantitative T2: application in a myocardial infarct model.

Left ventricular remodeling as a result of acute myocardial infarction (AMI) is associated with significant morbidity, leading to cardiovascular dysfunction, disability, and death. Despite successful revascularization, coronary vasodilatory dysfunction has been shown in infarcted and remote myocardium of patients following AMI. Our study explored the utility of a T(2)-based blood-oxygen-level-dependent approach in probing regional and longitudinal fluctuations in vasodilatory function in a porcine model of AMI at 3 T. Ten pigs underwent MRI in control state and at day 2, weeks 1-6 following 90 min occlusion followed by reperfusion. The remote myocardium exhibited vasodilatory dysfunction at weeks 1 and 2 that gradually recovered, whereas the infarct zone showed no vasodilatory alterations. Our study suggests that microvascular alterations occurring in infarcted and remote myocardium after AMI might serve as an indicator of adverse left ventricular remodeling. The blood-oxygen-level-dependent technique using quantitative T(2) could potentially be a useful noninvasive tool to evaluate novel therapeutic strategies aimed at limiting vasoconstriction and improving coronary flow reserve after AMI.