Photogrammetry of Perfusion-Fixed Heart : Innovative Approach to Study 3-Dimensional Cardiac Anatomy
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PROVIDER: S-EPMC10500340 | biostudies-literature | 2023 Jul
REPOSITORIES: biostudies-literature
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Project description:To develop a cardiac and respiratory self-gated four-dimensional (4D) coronary MRA technique for simultaneous cardiac anatomy and function visualization.A contrast-enhanced, ungated spoiled gradient echo sequence with self-gating (SG) and 3DPR trajectory was used for image acquisition. Data were retrospectively binned into different cardiac and respiratory phases based on information extracted from SG projections using principal component analysis. Each cardiac phase was reconstructed using a respiratory motion-corrected self-calibrating SENSE framework, and those belong to the quiescent period were retrospectively combined for coronary visualization. Healthy volunteer studies were conducted to evaluate the efficacy of the SG method, the accuracy of the left ventricle (LV) function parameters and the quality of coronary artery visualization.SG performed reliably for all subjects including one with poor electrocardiogram (ECG). The LV function parameters showed excellent agreement with those from a conventional cine protocol. For coronary imaging, the proposed method yielded comparable apparent signal to noise ratio and coronary sharpness and lower apparent contrast to noise ratio on three subjects compared with an ECG and navigator-gated Cartesian protocol and an ECG-gated, respiratory motion-corrected 3DPR protocol.A fully self-gated 4D whole-heart imaging technique was developed, potentially allowing cardiac anatomy and function assessment from a single measurement.
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Project description:Photogrammetry-based three-dimensional reconstruction of objects is becoming increasingly appealing in research areas unrelated to computer vision. It has the potential to facilitate the assessment of forest inventory-related parameters by enabling or expediting resource measurements in the field. We hereby compare several implementations of photogrammetric algorithms (CMVS/PMVS, CMPMVS, MVE, OpenMVS, SURE and Agisoft PhotoScan) with respect to their performance in vegetation assessment. The evaluation is based on (i) a virtual scene where the precise location and dimensionality of objects is known a priori and is thus conducive to a quantitative comparison and (ii) using series of in situ acquired photographs of vegetation with overlapping field of view where the photogrammetric outcomes are compared qualitatively. Performance is quantified by computing receiver operating characteristic curves that summarize the type-I and type-II errors between the reference and reconstructed tree models. Similar artefacts are observed in synthetic- and in situ-based reconstructions.
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Project description:The slice and view approach in electron microscopy defines an ensemble of destructive techniques that is widely used for studying in 3D the structure and chemistry of samples with dimensions ranging from µm to mm. Here, a method is presented for measuring with high resolution and quantitatively the morphology and chemical composition of the surface of a sample in 3D. It is non-destructive and therefore, it is complementary to slice and view methods. The scheme is based on the fusion of conventional scanning electron microscopy (SEM) imaging, multi-view photogrammetry and compositional mapping using energy dispersive X-ray spectroscopy (EDXS). We demonstrate its potential by performing an accurate study of adhesion wear of a tungsten carbide tool that is difficult to obtain using conventional characterization techniques.
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Project description:Cardiovascular diseases represent an economic burden for health systems accounting for substantial morbidity and mortality worldwide. Despite timely and costly efforts in drug development, the cardiovascular safety and efficacy of the drugs are not always fully achieved. These lead to the drugs' withdrawal with adverse cardiac effects from the market or in the late stages of drug development. There is a growing need for a cost-effective drug screening assay to rapidly detect potential acute drug cardiotoxicity. The Langendorff isolated heart perfusion technique, which provides cardiac hemodynamic parameters (e.g., contractile function and heart rate), has become a powerful approach in the early drug discovery phase to overcome drawbacks in the drug candidate's identification. However, traditional ex vivo retrograde heart perfusion methods consume a large volume of perfusate, which increases the cost and limits compound screening. An elegant and cost-effective alternative mode for ex vivo retrograde heart perfusion is the constant-flow with a recirculating circuit (CFCC), which allows assessment of cardiac function using a reduced perfusion volume while limiting adverse effects on the heart. Here, we provide evidence for cardiac parameters stability over time in this mode. Next, we demonstrate that our recycled ex vivo perfusion system and the traditional open one yield similar outputs on cardiac function under basal conditions and upon ?-adrenergic stimulation with isoproterenol. Subsequently, we validate the proof of concept of therapeutic agent screening using this efficient method. ?-blocker (i.e., propranolol) infusion in closed circulation countered the positive effects induced by isoproterenol stimulation on cardiac function. Keywords: Drug development, Drug screening, Cardiovascular safety, Langendorff method, Closed circulation.
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Project description:In previous work, the authors developed and demonstrated the concept of an image reconstruction procedure aimed to unify gated and dynamic nuclear cardiac imaging, which the authors have termed five-dimensional (5D) SPECT. Gated imaging permits the clinician to evaluate wall motion and, through the use of stress and rest scans, allows perfusion defects to be observed. Dynamic imaging depicts kinetics in the myocardium, which can be used to evaluate perfusion, but traditional dynamic images are motionless and do not depict wall motion. In this article, the authors investigate the degree to which perfusion defects can be detected from the dynamic information conveyed by 5D images, a problem that is particularly challenging in the absence of multiple fast camera rotations.The authors first demonstrate the usefulness of dynamic reconstructed images for perfusion detection by using linear discriminant analyses (Fisher linear discriminant analysis and principal component analysis) and a numerical channelized Hotelling observer. The authors then derive three types of discriminant metrics for characterizing the temporal kinetic information in reconstructed dynamic images for differentiating perfusion defects from normal cardiac perfusion, which are the Fisher linear discriminant map, temporal derivative map, and kinetic parametric images.Results are based on the NURBS-based cardiac-torso phantom with simulation of Tc99m-teboroxime as the imaging agent. The derived metric maps and quantitative contrast-to-noise ratio results demonstrate that the reconstructed dynamic images could yield higher detectability of the perfusion defect than conventional gated reconstruction while providing wall motion information simultaneously.The proposed metrics can be used to produce new types of visualizations, showing wall motion and perfusion information, that may potentially be useful for clinical evaluation. Since 5D imaging permits wall motion and kinetics to be observed simultaneously, it may ultimately obviate the need for separate stress and rest scans.
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Project description:Objectives A plethora of surgical strategies have been described to reach deep-seated lesions situated within the third ventricle including the Rosenfeld, or transcallosal anterior interfoniceal (TAIF), approach. First introduced in 2001, it consists of a small callosotomy followed by the midline transseptal dissection of fornices to enter the roof of the third ventricle. The aim of this microsurgical anatomy study is to describe and show each stage of the surgical procedure, focusing on the possible trajectories to anatomical landmarks. Participants A total of 20 adult cadaveric specimens were used in this study. Using ×3 to ×40 magnifications, the surgical dissection was performed in a stepwise fashion, and the transcallosal anterior interforniceal approach was performed, analyzed, and described. Results In 5 specimens of 10, a cavum septum pellucidum was depicted. In 5 cases of 20 after the callosotomy ,the lateral ventricular cavities were reached. Different orientation of the microscope allowed us to define three surgical trajectories to visualize the region of interest without exposing important functional areas. Conclusion The TAIF represents a minimally invasive approach to the third ventricle; its tricky surgical steps make appropriate anatomical dissection training essential to become confident and skilled in performing this approach.
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Project description:BackgroundSeveral indices exist to assess cerebral perfusion after cardiac arrest (CA). We aimed to investigate a new approach allowing absolute flow and microvascular resistance measurement based on selective arterial continuous thermodilution before and after CA resuscitation in a porcine model.MethodsIn anaesthetised pigs, intravascular absolute cerebral blood flow (CBF) and absolute coronary blood flow (ABF) with corresponding microvascular resistances were measured. CA was induced using overdrive pacing with 3 (group 1, n = 5) or 5 min (group 2, n = 8) of no flow. After resuscitation, CBF was performed at baseline, at 15 min (T15) and at 30 min (T30). Thereafter, CBF in the contralateral cerebral artery and ABF were measured.ResultsThe protocol could not be completed in three pigs from group 2 due to haemodynamic instability. In the entire cohort, CBF was significantly lower at T30 after CA (0.026 ± 0.02 L/min vs 0.040 ± 0.03 at baseline; p = 0.03) and cerebral microvascular resistances were significantly higher (3202 ± 1838 Woods units vs 2014 ± 1015 at baseline; p = 0.04). ABF and resistances remained stable at baseline, as compared to T30 (0.122 ± 0.05 vs. 0.143 ± 0.06 L/min; p = 0.15 and 563 ± 203 vs. 478 ± 181 Woods units; p = 0.36, respectively). At T30, no significant differences in cerebral flow dynamics were observed between groups.ConclusionsABF and CBF measurement after CA resuscitation is feasible with thermodilution technique, allowing accurate monitoring and measurements. This novel approach allows simultaneous measurements of flow and microvascular resistances. This animal model simplifies cerebral perfusion measurements and allows to test new therapies to reduce cerebral injury post cardiac arrest.
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