Ringraziamo Drs. Raimond Winslow, Elliot McVeigh, Helm e Patrick presso la Johns Hopkins University per fornire il set di dati ex vivo online.This ricerca è stata sostenuta dal National Institutes of Health di sovvenzione R01-HL082729, e la National Science Foundation concessione CBET-0933029.

1. Fibra Orientamenti Stima <ol><li> Acquisire strutturali immagini MRI e DTMRI di un cuore umano adulto normale in diastole, con una risoluzione di 1 mm 3. Uso ImageJ, estrarre il miocardio ventricolare dall&#39;immagine atlante strutturale raccordo, per ciascun asse corto slice, spline chiusa attraverso una serie di punti limite disposte lungo i confini epicardici ed endocardici nella fetta (Figura 2A e 2B Figura). Eseguire il posizionamento dei punti limite manualmente per ogni fetta 10 th nell&#39;immagine. Ottenere i punti limite per le rimanenti fette interpolando linearmente i punti individuati manualmente, utilizzando i MATLAB.Reconstruct orientamento delle fibre del cuore atlante calcolando gli autovettori primari dei DTs nell&#39;immagine DTMRI (Figura 2C). </li><li> Acquisire un&#39;immagine della geometria del cuore del paziente in diastole usando in vivo cardiaca CT o MRI. Reconstruire la geometria paziente cuore dall&#39;immagine simile al modo in cui è stato costruito l&#39;atlante (Figura 3A e 3B Figura). L&#39;immagine paziente deve essere nuovamente campionati prima ricostruzione tale che la risoluzione in piano è di 1 mm 2. Analogamente, il numero di fette per cui punti di riferimento sono raccolte manualmente, e l&#39;intervallo di fuori del piano di interpolazione deve essere regolato in modo che l&#39;immagine segmentata cuore paziente ha uno spessore di strato di 1 mm. </li><li> Deforma l&#39;immagine ventricolare atlante in modo che corrisponda all&#39;immagine paziente geometria in due fasi. Nella prima fase, eseguire una trasformazione affine basato su un insieme di tredici punti monumenti: il ventricolo sinistro (LV) apice, le due ventricolare destro (RV) punti di inserimento alla base, l&#39;inserimento due metà RV punti tra base e apice, e quattro serie di due punti che dividono in modo uniforme per camper e contorni LV epicardici alla base, ed a metà strada tra la base e il vertice (Figura 4A &amp; <strong&gt; Figura 4B). Nella seconda fase, la deformazione affine-atlante trasformato ventricoli ulteriore geometria adatta al paziente, utilizzando grandi mappatura diffeomorphic metrica deformazione (LDDMM) (Figura 4C). </li><li> Morph l&#39;immagine DTMRI dell&#39;atlante riposizionando di voxel immagine e riorientamento DTS secondo la matrice di trasformazione affine della corrispondenza e il campo di deformazione della trasformazione LDDMM. Eseguire la ri-orientamento dei DTs con la conservazione di direzioni principali (PPD) metodo. </li><li> Ottenere la stima degli orientamenti fibra del paziente dal morphed immagine atlante DTMRI calcolando l&#39;autovettore principale del DTs (Figura 5). </li></ol> 2. Misurazione di errore di stima <ol><li> Acquisire ex vivo strutturale MR e immagini DTMR di sei cuori fallimento normali e tre canini, con una risoluzione di 312,5 × 312,5 × 800 micron 3. Qui, cuore fairichiamo deve essere generata in canini mediante ablazione con radiofrequenza della branca sinistro seguito da 3 settimane di tachypacing a 210 min -1. </li><li> Segmento i ventricoli dal cuore canino simile al cuore umano atlante, come descritto nel § 1.1. Indichiamo ventricoli segmentati dalle normali cuore canino come cuori da 1 a 6, e quelli segmentato dalla mancata cuore canino come cuori da 7 a 9 (Figura 6). </li><li> Ottenere cinque diverse stime orientamenti ventricolari fibra di cuore 1 utilizzando ciascuno dei cuori 2 a 6 come un atlante (Figura 7). </li><li> Stimare orientamento delle fibre per ciascuno dei ventricoli fallimento usando cuore 1 come l&#39;atlante (Figura 8). </li><li> Foreach punto dati di ogni serie di orientamento delle fibre stimati, calcolare l&#39;errore di stima come | θ c-θ un |, dove θ c e θ sono un gli angoli di inclinazione di una stimad acquisito orientamento delle fibre in quel punto, rispettivamente. </li><li> Per ciascun punto di dati in ogni serie di orientamento delle fibre stimati, calcolare l&#39;angolo acuto betweenestimated e acquisito indicazioni fibra in tre dimensioni (3D) mediante prodotto thevector dot. </li></ol> 3. Misurazione degli effetti di errore di stima sulle Simulazioni <ol><li> Dal cuore 1, costruire sei modelli, uno con gli DTMRI-acquisiti orientamento delle fibre del cuore 1 (indicato come modello 1), e cinque con cinque serie di dati stimati orientamento delle fibre (modelli 2 a 6). Per ciascuno dei tre omettendo cuore geometrie, costruire due modelli ventricolari, uno con i DTMRI acquisite orientamento delle fibre e l&#39;altra con gli orientamenti in fibra stimati. Qui la risoluzione spaziale dei modelli, calcolata in termini di lunghezza del bordo media delle maglie, dovrebbe essere di circa 600 micron. Indichiamo i modelli di scompenso cardiaco con fibre DTMRI-acquisiti e modelli 7 a 9, e quelli con estimatEd fibre come modelli da 10 a 12.In i modelli, utilizzare la rappresentazione monodominio per descrivere il tessuto cardiaco, con le equazioni che disciplinano: </li></ol><img src="/files/ftp_upload/50125/50125eq1.jpg" alt="Equazione 1" fo:content-width="2.18in" fo:src="/files/ftp_upload/50125/50125eq1highres.jpg" /> dove σ b è il tensore di conduttività che è calcolato dai tensori conducibilità bidomain come descritto da Potse et al 30; V m è il potenziale transmembrana; C m è la capacità di membrana specifico e io Ion è la densità della corrente transmembrana, che a sua volta dipende V m e un insieme di variabili di stato μ descrivere le dinamiche di flussi ionici attraverso il C membrane.For m, utilizzare un valore di 1 μ F / cm 2. Per i normali modelli σ in cuore canini, utilizzare longitudinalivalori di conducibilità nali e trasversale di 0,34 S / m e 0,06 S / m, rispettivamente. Rappresentare l lon dai Greenstein-Winslow modelli ionici del miociti ventricolari canino. Diminuire le conducibilità elettrica nei modelli canini insufficienza cardiaca ventricolare del 30% (Figura 9). <ol start="2"><li> Utilizzo del pacchetto software CARP (CardioSolv, LLC), ritmo sinusale con tutti i modelli di simulazione. Indurre tachicardia rientrante ventricolare (VT) nei sei modelli fallimento utilizzando un S1-S2 protocollo di stimolazione. Scegliere il tempo tra S1 e S2 per ottenere l&#39;attività VT sostenuta per 2 secondi dopo la consegna S2. Se VT non viene indotta per qualsiasi S1-S2 temporizzazione, diminuire la conducibilità fino al 70% fino VT è stato indotto (Figura 10). </li><li> Per ogni simulazione, il calcolo pseudo-ECG prendendo la differenza di potenziale tra due punti extracellulari in bagno isotropo che circonda il cuore. Posizionare i due punti vicino alla base del cuore separatoda 18 cm, in modo tale che la linea che li collega è perpendicolare al piano di base-apice del setto come illustrato in Figura 10. Per ogni simulazione con orientamento delle fibre stimati, calcolare la metrica come MAD </li></ol><img src="/files/ftp_upload/50125/50125eq2.jpg" alt="Equazione 2" fo:content-width="2.77in" fo:src="/files/ftp_upload/50125/50125eq2highres.jpg" /> dove X è la forma d&#39;onda ECG della simulazione con orientamento delle fibre stimati, Y è la forma d&#39;onda ECG thecorresponding di simulazione con orientamento delle fibre acquisite, X è il valore medio di X, Y è il valore medio di Y, ed n è la lunghezza di X e Y.

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Nessun conflitto di interessi dichiarati.

Questa ricerca dimostra quantitativamente che, in assenza di DTMRI, orientamento delle fibre miocardiche di ventricoli normali e mancanza può essere stimata in vivo immagini delle loro geometrie per uso in simulazioni di elettrofisiologia cardiaca. La metodologia proposta è stata dimostrata in vivo dati CT, ma è ugualmente applicabile a immagini RM in vivo della geometria ventricolare, affrontando la mancanza di capacità di acquisire direttamente orientamento delle fibre del paziente. E &#...

<html> L&#39;approccio computazionale sta diventando centrale per l&#39;avanzamento della comprensione della funzione del cuore in salute e malattia. State-of-the-art con tutto il cuore i modelli di elettrofisiologia ed elettromeccanica sono attualmente utilizzate per studiare una vasta gamma di fenomeni, come ad esempio la propagazione ventricolare normale, aritmia, defibrillazione, accoppiamento elettromeccanico, e di resincronizzazione cardiaca 1. Tuttavia, per l&#39;approccio computazionale per essere direttamente applicabile in ambiente clinico, è imperativo che i modelli di essere paziente-specifico, cioè i modelli deve essere basata sull&#39;architettura specifico e proprietà elettrofisiologiche o elettromeccanici del cuore malato del paziente. Simulazione con tali modelli sarà di aiuto ai medici di arrivare a decisioni altamente personalizzati per gli interventi elettrofisiologiche così come profilassi, in tal modo notevolmente migliorare l&#39;assistenza sanitaria cardiaco 2-4. contenuto &quot;&gt; Creazione di modelli realistici cardiaci richiede l&#39;acquisizione della struttura di geometria e fibre di un cuore paziente. orientamento delle fibre determinare direzioni di propagazione elettrica e distribuzioni di deformazione nel cuore, e quindi il loro acquisto è essenziale per la modellazione cardiaca 5, 6. Con recenti progressi nella diagnostica per immagini, è ora possibile ottenere la geometria di un cuore paziente, rimodellamento includingstructural come l&#39;infarto, in vivo con alta risoluzione mediante risonanza magnetica (MRI) e la tomografia computerizzata (CT) tecnologie. Tuttavia, non vi è alcuna metodo pratico per acquisire struttura fibrosa di un cuore paziente in vivo. Diffusion tensor (DT) MRI 7, 8, l&#39;unica tecnica per acquisire orientamento delle fibre del cuore intatto, non è ampiamente disponibile in vivo a causa di alcune limitazioni 9. Breve descrizione degli sforzi precedenti per tradurre DTMRI alla clinica può essere trovato elsewhere 2. Anche se metodologie come basato su regole assegnazione di orientamento delle fibre di offrire alternative a DTMRI, queste metodologie hanno alcune limitazioni gravi 2, 10. Così difficoltà nell&#39;acquisire struttura cardiaca in vivo attualmente in fibra di ostacolare l&#39;applicazione delle simulazioni elettrofisiologici cardiaci ed elettromeccanica in ambiente clinico. L&#39;obiettivo di questa ricerca è stato quello di rivolgersi direttamente a questa esigenza. Abbiamo ipotizzato che orientamenti ventricolari fibra di un cuore può essere previsto con precisione, data la geometria del cuore e un atlante, dove l&#39;atlante è un cuore cui geometria e fibra orientamenti sono disponibili. Di conseguenza, abbiamo usato lo stato dell&#39;arte delle tecniche di sviluppare una metodologia per la stima di orientamento delle fibre cardiache in vivo, e testato l&#39;ipotesi in condizioni normali e in mancanza di ventricoli canino 2. L&#39;idea centrale della nostra metodologia di stima delle fibre è quello di sfruttare similarities in orientamento delle fibre, relativi alla geometria, tra le diverse anime, al fine di avvicinare la struttura fibrosa di un (target) di cuore per cui solo le informazioni sulla geometria è disponibile. Al centro della nostra metodologia di stima è la registrazione della geometria atlante con la geometria di destinazione utilizzando grandi mappatura diffeomorphic metrica deformazione (LDDMM) 11, e l&#39;orientamento delle fibre di morphing atlante utilizzando conservazione delle componenti principali (PPD) 2, 12. La diffeomorphicproperty di garanzie LDDMM che l&#39;atlante non &quot;deployante&quot; stesso durante la deformazione, in modo da preservare le strutture anatomiche integrityof. Figura 1 illustra la pipeline di elaborazione della nostra metodologia. La sezione di testo protocollo § 1 descrive i vari componenti della pipeline dimostrando come la stima può essere eseguita per esempio un paziente. I numeri all&#39;interno alcuni dei blocchi in figura 1 si riferiscono alla corrispondentesottosezioni di cui alla sezione § 1 del testo del protocollo. Abbiamo valutato le prestazioni della metodologia proposta, che quantifica l&#39;errore di stima, e misurare l&#39;effetto di questo onsimulations errore di elettrofisiologia cardiaca, per la simulazione computazionale locali mappe di attivazione elettrici così come pseudo-elettrocardiogrammi (pseudo-ECG). A causa della indisponibilità dei cuori umani, la valutazione delle prestazioni è stata condotta utilizzando i cuori canine disponibili da studi precedenti 13-15. L&#39;errore di stima è stata calcolata mediante angoli di inclinazione 16, tradizione followingthe di istologia, dove le misure angolari sono sezioni di tessuto performedon che sono tagliati parallelamente al epicardialsurface. Poiché il anglebetween direzione delle fibre ed epicardici piano tangente è generallysmall 17, 18, ​​la perdita di informazioni nel descrivere un fiberdirection interamente con il suo angolo di inclinazione è insignificante. Per il computnazionali di simulazioni, image-based modelli sono stati costruiti come riportato in precedenza 19, 20, e il tessuto cardiaco nei modelli è stata rappresentata sulla base stabiliti tecniche matematiche e dati sperimentali 21-25. Ritmo sinusale è stato simulato attivazione replica proveniente dalla rete Purkinje 26, e la tachicardia ventricolare, da un S1-S2 stimolazione protocollo 27. Pseudo-ECG sono stati calcolati 28 e confrontati utilizzando la deviazione media assoluta (MAD) metrica 29.

<table border="1"><tbody><tr><td> LDDMM </td><td> Johns Hopkins University </td><td></td><td> <a href="http://cis.jhu.edu/software/lddmm-volume/index.php" target="_blank">http://cis.jhu.edu/software/lddmm-volume/index.php</a> </td></tr><tr><td> MATLAB </td><td> MathWorks, Inc. </td><td> R2011b </td><td> <a href="http://www.mathworks.com/products/matlab/" target="_blank">http://www.mathworks.com/products/matlab/</a> </td></tr><tr><td> ImageJ </td><td> National Institutes of Health </td><td></td><td> <a href="http://rsbweb.nih.gov/ij/" target="_blank">http://rsbweb.nih.gov/ij/</a> </td></tr><tr><td> Tarantola </td><td> CAE Software Solutions </td><td></td><td> <a href="http://www.meshing.at/Spiderhome/Tarantula.html" target="_blank">http://www.meshing.at/Spiderhome/Tarantula.html</a> </td></tr><tr><td> CARP </td><td> CardioSolv</td><td></td><td> <a href="http://cardiosolv.com/" target="_blank">http://cardiosolv.com/</a> </td></tr><tr><td> Immagini Canine </td><td> Johns Hopkins University </td><td></td><td> <a href="http://www.ccbm.jhu.edu/research/DTMRIDS.php" target="_blank">http://www.ccbm.jhu.edu/research/DTMRIDS.php</a> </td></tr></tbody></table>

patient-specific modeling of the heart: estimation of ventricular fiber orientations

Paziente-specifiche simulazioni di cuore (dis) funzione volta a personalizzare la terapia cardiaca sono ostacolati dalla mancanza di tecnologia di imaging in vivo per l&#39;acquisizione clinicamente orientamento delle fibre miocardiche. L&#39;obiettivo di questo progetto era quello di sviluppare una metodologia per la stima orientamento delle fibre cardiache dal vivo in immagini di geometrie del cuore del paziente. Una rappresentazione accurata della geometria ventricolare e orientamento delle fibre è stato ricostruito, rispettivamente, di alta risoluzione risonanza ex vivo strutturale magnetica (RM) e del tensore di diffusione (DT) immagini RM di un cuore umano normale, indicato come l&#39;atlante. Geometria ventricolare di un cuore paziente è stato estratto, tramite segmentazione semiautomatico, da una in vivo la tomografia computerizzata (TC) delle immagini. Utilizzando algoritmi di trasformazione di immagini, la geometria ventricolare atlante è stato deformato in base a quella del paziente. Infine, il campo di deformazione è stato applicato alla fibra atlante Orientationioni per ottenere una stima di orientamento delle fibre del paziente. La precisione delle stime di fibre è stata valutata utilizzando sei cuori in mancanza di normali e tre cani. La differenza media assoluta tra angoli di inclinazione di orientamento delle fibre acquisite e stimata è stata di 15,4 °. Simulazioni computazionali di mappe di attivazione ventricolare e pseudo-ECG in ritmo sinusale e tachicardia ventricolare indicato che non vi sono differenze significative tra orientamento delle fibre stimati e acquisito in generale clinicamente osservabili intuizioni level.The nuove ottenuti dal progetto aprirà la strada per lo sviluppo di paziente-specifici modelli del cuore che può aiutare i medici nella diagnosi personalizzata e le decisioni in materia di interventi di elettrofisiologia.

Figura 11, AC visualizza visualizzazioni semplificati di stima e DTMRI derivati ​​orientamento delle fibre nei cuori normali e in mancanza. Esame qualitativa mostra che gli orientamenti in fibra stimati allineano bene con DTMRI derivati ​​da quelli. Pannello D illustra, sovrapposto sulla geometria del cuore 1, la distribuzione di errore in angoli di inclinazione cuori normali &quot;, mediato su tutte e cinque le stime. Pannello E mostra la distribuzione media di errore omettendo angoli di inclin...

Watch this Scientific Journal Video about Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations at JoVE.com

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

Una metodologia per la stima orientamento delle fibre ventricolari da immagini in vivo di geometrie del cuore del paziente per la modellazione personalizzata è descritto. Validazione della metodologia effettuata con una normale e in mancanza di cuori canini dimostrare che non ci sono differenze significative tra orientamento delle fibre stimati e ha acquisito a livello clinicamente osservabile.

Paziente-specifica modellazione del Cuore: Stima di orientamento delle fibre ventricolari

Patient-specific  simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered  by the absence of in vivo imaging technology for ...

patient-specific-modeling-heart-estimation-ventricular-fiber

Research

JoVE Journal

Bioengineering

13.6K Views.  Johns Hopkins University. Una metodologia per la stima orientamento delle fibre ventricolari da immagini in vivo di geometrie del cuore del paziente per la modellazione personalizzata è descritto. Validazione della metodologia effettuata con una normale e in mancanza di cuori canini dimostrare che non ci sono differenze significative tra orientamento delle fibre stimati e ha acquisito a livello clinicamente osservabile.

Video: Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution. Traditionally, multiple experiments are run in parallel, with individual samples removed from the study at sequential time points for evaluation by light microscopy. Several intravital techniques have been developed, with confocal, multiphoton, and second harmonic microscopy all demonstrating their ability to be used for imaging in situ 1. With these systems, however, the required infrastructure is complex and expensive, involving scanning laser systems and complex light sources. Here we present a protocol for the design and assembly of a high-resolution microendoscope which can be built in a day using off-the-shelf components for under US$5,000. The platform offers flexibility in terms of image resolution, field-of-view, and operating wavelength, and we describe how these parameters can be easily modified to meet the specific needs of the end user.
We and others have explored the use of the high-resolution microendoscope (HRME) in in vitro cell culture 2-5, in excised 6 and living animal tissues 2,5, and in human tissues in vivo 2,7. Users have reported the use of several different fluorescent contrast agents, including proflavine 2-4, benzoporphyrin-derivative monoacid ring A (BPD-MA) 5, and fluoroscein 6,7, all of which have received full, or investigational approval from the FDA for use in human subjects. High-resolution microendoscopy, in the form described here, may appeal to a wide range of researchers working in the basic and clinical sciences. The technique offers an effective and economical approach which complements traditional benchtop microscopy, by enabling the user to perform high-resolution, longitudinal imaging in situ.

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

In many biological and clinical situations it is advantageous to study cellular processes as they evolve in their native microenvironment. Here we describe the assembly and use of a low-cost fiber-optic microscope which can provide real time imaging in cell culture, animal studies, and clinical patient studies.

Ad alta risoluzione in fibra ottica per Microendoscopy In situ Cellular Imaging

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution.  ...

Ricerca

Bioingegneria

Multiparametric Optical Mapping of the Langendorff-perfused Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not have been accomplished by other approaches1. With the use of the calcium- and voltage-sensitive dyes, optical mapping allows measurement of transmembrane action potentials and calcium transients with high spatial resolution without the physical contact with the tissue. This makes measurements of the cardiac electrical activity possible under many conditions where the use of electrodes is inconvenient or impossible1. For example, optical recordings provide accurate morphological changes of membrane potential during and immediately after stimulation and defibrillation, while conventional electrode techniques suffer from stimulus-induced artifacts during and after stimuli due to electrode polarization1. 
The Langendorff-perfused rabbit heart is one of the most studied models of human heart physiology and pathophysiology. Many types of arrhythmias observed clinically could be recapitulated in the rabbit heart model. It was shown that wave patterns in the rabbit heart during ventricular arrhythmias, determined by effective size of the heart and the wavelength of reentry, are very similar to that in the human heart2. It was also shown that critical aspects of excitation-contraction (EC) coupling in rabbit myocardium, such as the relative contribution of sarcoplasmic reticulum (SR), is very similar to human EC coupling3. Here we present the basic procedures of optical mapping experiments in Langendorff-perfused rabbit hearts, including the Langendorff perfusion system setup, the optical mapping systems setup, the isolation and cannulation of the heart, perfusion and dye-staining of the heart, excitation-contraction uncoupling, and collection of optical signals. These methods could be also applied to the heart from species other than rabbit with adjustments to flow rates, optics, solutions, etc.
Two optical mapping systems are described. The panoramic mapping system is used to map the entire epicardium of the rabbit heart4-7. This system provides a global view of the evolution of reentrant circuits during arrhythmogenesis and defibrillation, and has been used to study the mechanisms of arrhythmias and antiarrhythmia therapy8,9. The dual mapping system is used to map the action potential (AP) and calcium transient (CaT) simultaneously from the same field of view10-13. This approach has enhanced our understanding of the important role of calcium in the electrical alternans and the induction of arrhythmia14-16.

This article describes the basic procedures for conducting optical mapping experiments in the Langendorff-perfused rabbit heart using the panoramic imaging system, and the dual (voltage and calcium) imaging modality.

Multiparametrica mappatura ottica del Langendorff-perfuso Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not ...

Targeting Neuronal Fiber Tracts for Deep Brain Stimulation Therapy Using Interactive, Patient-Specific Models

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for movement disorders and is being applied to a growing number of disorders. Computational modeling has been successfully used to predict the clinical effects of DBS; however, there is a need for novel modeling techniques to keep pace with the growing complexity of DBS devices. These models also need to generate predictions quickly and accurately. The goal of this project is to develop an image processing pipeline to incorporate structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) into an interactive, patient specific model to simulate the effects of DBS. A virtual DBS lead can be placed inside of the patient model, along with active contacts and stimulation settings, where changes in lead position or orientation generate a new finite element mesh and solution of the bioelectric field problem in near real-time, a timespan of approximately 10 seconds. This system also enables the simulation of multiple leads in close proximity to allow for current steering by varying anodes and cathodes on different leads. The techniques presented in this paper reduce the burden of generating and using computational models while providing meaningful feedback about the effects of electrode position, electrode design, and stimulation configurations to researchers or clinicians who may not be modeling experts.

The goal of this project is to develop an interactive, patient-specific modeling pipeline to simulate the effects of deep brain stimulation in near real-time and provide meaningful feedback as to how these devices influence neural activity in the brain.

Tratti della fibra di un neurone di targeting per la terapia di stimolazione cerebrale profonda utilizzando modelli interattivi, specifico per ogni paziente

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for ...

Light-sheet Fluorescence Microscopy for the Study of the Murine Heart

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. Traditional light-sheet techniques involve the use of a single illumination beam directed orthogonally at sample tissue. Images of large samples that are produced using a single illumination beam contain stripes or artifacts and suffer from a reduced resolution due to the scattering and absorption of light by the tissue. This study uses a dual-sided illumination beam and a simplified CLARITY optical clearing technique for the murine heart. These techniques allow for deeper imaging by removing lipids from the heart and produce a large field of imaging, greater than 10 x 10 x 10 mm3. As a result, this strategy enables us to quantify the ventricular dimensions, track the cardiac lineage, and localize the spatial distribution of cardiac-specific proteins and ion-channels from the post-natal to adult mouse hearts with sufficient contrast and resolution.

This study uses a dual-sided illumination light-sheet fluorescence microscopy (LSFM) technique combined with optical clearing to study the murine heart.

Microscopia di fluorescenza di luce-foglio per lo studio del cuore murino

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. ...

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive models, which provide a mathematical representation of the mechanical function of those structures. This presented biaxial mechanical testing protocol involves (i) tissue acquisition, (ii) the preparation of tissue specimens, (iii) biaxial mechanical testing, and (iv) postprocessing of the acquired data. First, tissue acquisition requires obtaining porcine or ovine hearts from a local Food and Drug Administration-approved abattoir for later dissection to retrieve the valve leaflets. Second, tissue preparation requires using tissue specimen cutters on the leaflet tissue to extract a clear zone for testing. Third, biaxial mechanical testing of the leaflet specimen requires the use of a commercial biaxial mechanical tester, which consists of force-controlled, displacement-controlled, and stress-relaxation testing protocols to characterize the leaflet tissue&#39;s mechanical properties. Finally, post-processing requires the use of data image correlation techniques and force and displacement readings to summarize the tissue&#39;s mechanical behaviors in response to external loading. In general, results from biaxial testing demonstrate that the leaflet tissues yield a nonlinear, anisotropic mechanical response. The presented biaxial testing procedure is advantageous to other methods since the method presented here allows for a more comprehensive characterization of the valve leaflet tissue under one unified testing scheme, as opposed to separate testing protocols on different tissue specimens. The proposed testing method has its limitations in that shear stress is potentially present in the tissue sample. However, any potential shear is presumed negligible.

This protocol involves characterizations of atrioventricular valve leaflets with force-controlled, displacement-controlled, and stress-relaxation biaxial mechanical testing procedures. Results acquired with this protocol can be used for constitutive model development to simulate the mechanical behavior of functioning valves under a finite element simulation framework.

Caratterizzazioni biassiale meccaniche delle valvole atrioventricolari cuore

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive ...

Optical Imaging of Isolated Murine Ventricular Myocytes

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances in calcium sensitive dyes have permitted the robust optical recording of single cell calcium dynamics, recording of robust transmembrane optical voltage signals has remained difficult. Arguably, this is because of the low single to noise ratio, phototoxicity, and photobleaching of traditional potentiometric dyes. Therefore, single cell voltage measurements have long been confined to the patch clamp technique which while the gold standard, is technically demanding and low throughput. However, with the development of novel potentiometric dyes, large, fast optical responses to changes in voltage can be obtained with little to no phototoxicity and photobleaching. This protocol describes in detail how to isolate adult murine myocytes which can be used for cellular shortening, calcium, and optical voltage measurements. Specifically, the protocol describes how to use a ratiometric calcium dye, a single-excitation calcium dye, and a single excitation voltage dye. This approach can be used to assess the cardiotoxicity and arrhythmogenicity of various chemical agents. While phototoxicity is still an issue at the single cell level, methodology is discussed on how to reduce it.

We present the methodology for the isolation of murine myocytes and how to obtain voltage or calcium traces simultaneously with sarcomere shortening traces using fluorescence photometry with simultaneous digital cell geometry measurements.

Imaging ottico di miociti Murine Ventricolari isolati

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances ...

Evaluation of Left Ventricular Structure and Function using 3D Echocardiography

Three-dimensional (3D) quantification of the left ventricle (LV) provides significant added value in terms of diagnostic accuracy and precise risk stratification in various cardiac disorders. Recently, 3D echocardiography became available in routine cardiology practice; however, high-quality image acquisition and subsequent analysis have a steep learning curve. The present article aims to guide the reader through a detailed 3D protocol by presenting tips and tricks and also by highlighting the potential pitfalls to facilitate the widespread but technically sound use of this important technique concerning the LV. First and foremost, we show the acquisition of a high-quality 3D dataset with optimal spatial and temporal resolution. Then, we present the analytical steps toward a detailed quantification of the LV by using one of the most widely applied built-in software. We will quantify LV volumes, sphericity, mass and also systolic function by measuring ejection fraction and myocardial deformation (longitudinal and circumferential strain). We will discuss and provide clinical examples about the essential scenarios where the transition from a conventional echocardiographic approach to a 3D-based quantification is highly recommended.

In this article, we provide a step-by-step acquisition and analysis protocol for the volumetric assessment and speckle-tracking analysis of the left ventricle by 3D echocardiography, particularly focusing on practical aspects that maximize the feasibility of this technique.

Valutazione della struttura e della funzione ventricolare sinistra mediante ecocardiografia 3D

Three-dimensional (3D) quantification of the left ventricle (LV) provides significant added value in terms of diagnostic accuracy and precise risk ...

Patient-Specific Polyvinyl Alcohol Phantom Fabrication with Ultrasound and X-Ray Contrast for Brain Tumor Surgery Planning

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create anatomically accurate head phantoms with realistic brain imaging properties because standard fabrication methods are not optimized to replicate any patient-specific anatomical detail and 3D printing materials are not optimized for imaging properties. In order to test and validate a novel navigation system for use during brain tumor surgery, an anatomically accurate phantom with realistic imaging and mechanical properties was required. Therefore, a phantom was developed using real patient data as input and 3D printing of molds to fabricate a patient-specific head phantom comprising the skull, brain and tumor with both ultrasound and X-ray contrast. The phantom also had mechanical properties that allowed the phantom tissue to be manipulated in a similar manner to how human brain tissue is handled during surgery. The phantom was successfully tested during a surgical simulation in a virtual operating room.
The phantom fabrication method uses commercially available materials and is easy to reproduce. The 3D printing files can be readily shared, and the technique can be adapted to encompass many different types of tumor.

This protocol describes the fabrication of a patient specific skull, brain and tumor phantom. It uses 3D printing to create molds, and polyvinyl alcohol (PVA-c) is used as the tissue mimicking material.

Fabbricazione fantasma di alcol polivinile specifico per il paziente con ultrasuoni e contrasto a raggi X per la pianificazione della chirurgia del tumore al cervello

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create ...

Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict regional aerosol delivery. Leveraging 3D printing to generate patient-specific lung models, we outline the design of a high-throughput, in vitro experimental setup for quantifying lobular pulmonary deposition. This system is made with a combination of commercially available and 3D printed components and allows the flow rate through each lobe of the lung to be independently controlled. Delivery of fluorescent aerosols to each lobe is measured using fluorescence microscopy. This protocol has the potential to promote the growth of personalized medicine for respiratory diseases through its ability to model a wide range of patient demographics and disease states. Both the geometry of the 3D printed lung model and the air flow profile setting can be easily modulated to reflect clinical data for patients with varying age, race, and gender. Clinically relevant drug delivery devices, such as the endotracheal tube shown here, can be incorporated into the testing setup to more accurately predict a device&#8217;s capacity to target therapeutic delivery to a diseased region of the lung. The versatility of this experimental setup allows it to be customized to reflect a multitude of inhalation conditions, enhancing the rigor of preclinical therapeutic testing.

We present a high-throughput, in vitro method for quantifying regional pulmonary deposition at the lobe level using CT scan-derived, 3D printed lung models with tunable air flow profiles.

Valutazione della deposizione polmonare regionale utilizzando modelli polmonari stampati in 3D specifici del paziente

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict ...

Quantification of Mouse Heart Left Ventricular Function, Myocardial Strain, and Hemodynamic Forces by Cardiovascular Magnetic Resonance Imaging

Mouse models have contributed significantly to understanding genetic and physiological factors involved in healthy cardiac function, how perturbations result in pathology, and how myocardial diseases may be treated. Cardiovascular magnetic resonance imaging (CMR) has become an indispensable tool for a comprehensive in vivo assessment of cardiac anatomy and function. This protocol shows detailed measurements of mouse heart left ventricular function, myocardial strain, and hemodynamic forces using 7-Tesla CMR. First, animal preparation and positioning in the scanner are demonstrated. Survey scans are performed for planning imaging slices in various short- and long-axis views. A series of prospective ECG-triggered short-axis (SA) movies (or CINE images) are acquired covering the heart from apex to base, capturing end-systolic and end-diastolic phases. Subsequently, single-slice, retrospectively gated CINE images are acquired in a midventricular SA view, and in 2-, 3-, and 4-chamber views, to be reconstructed into high-temporal resolution CINE images using custom-built and open-source software. CINE images are subsequently analyzed using dedicated CMR image analysis software.
Delineating endomyocardial and epicardial borders in SA end-systolic and end-diastolic CINE images allows for the calculation of end-systolic and end-diastolic volumes, ejection fraction, and cardiac output. The midventricular SA CINE images are delineated for all cardiac time frames to extract a detailed volume-time curve. Its time derivative allows for the calculation of the diastolic function as the ratio of the early filling and atrial contraction waves. Finally, left ventricular endocardial walls in the 2-, 3-, and 4-chamber views are delineated using feature-tracking, from which longitudinal myocardial strain parameters and left ventricular hemodynamic forces are calculated. In conclusion, this protocol provides detailed in vivo quantification of the mouse cardiac parameters, which can be used to study temporal alterations in cardiac function in various mouse models of heart disease.

This study describes a comprehensive cardiovascular magnetic resonance imaging (CMR) protocol to quantify the left ventricular functional parameters of the mouse heart. The protocol describes the acquisition, post-processing, and analysis of the CMR images as well as assessment of different cardiac functional parameters.

Quantificazione della funzione ventricolare sinistra del cuore di topo, del ceppo miocardico e delle forze emodinamiche mediante risonanza magnetica cardiovascolare

Mouse models have contributed significantly to understanding genetic and physiological factors involved in healthy cardiac function, how perturbations ...