Geometrical and Hemodynamic Variables for Thrombotic Risk Stratification in Kawasaki Disease

Objectives Thrombosis is a major adverse outcome for coronary artery aneurysms (CAA) in Kawasaki disease (KD). We investigated the geometric and hemodynamic abnormalities in patients with CAA and identified the risk factors for thrombosis by computational fluid dynamics (CFD) simulation. Methods We retrospectively studied 27 KD patients with 77 CAAs, including 20 CAAs with thrombosis in 12 patients. Patient-specific anatomic models obtained from cardiac magnetic resonance imaging (CMRI) were constructed to perform a CFD simulation. From the simulation results, we produced local hemodynamic parameters comprising of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI) and relative resident time (RRT). The CAA’s maximum diameter (Dmax) and Z-score were measured on CMRI. Results Giant CAAs tended to present with more severe hemodynamic abnormalities. Thrombosed CAAs exhibited lower TAWSS (1.551 ± 1.535 vs. 4.235 ± 4.640dynes/cm2, p = 0.002), higher Dmax (10.905 ± 4.125 vs. 5.791 ± 2.826mm, p = 0.008), Z-score (28.301 ± 13.558 vs. 13.045 ± 8.394, p = 0.002), OSI (0.129 ± 0.132 vs. 0.046 ± 0.080, p = 0.01), and RRT (16.780 ± 11.982s vs. 9.123 ± 11.770s, p = 0.399) than the non-thrombosed group. An ROC analysis for thrombotic risk proved that all of the five parameters had area under the ROC curves (AUC) above 0.7, with Dmax delineating the highest AUC (AUCDmax = 0.871) and a 90% sensitivity, followed by Z-score (AUCZ−score = 0.849). Conclusions It is reasonable to combine the geometric index with hemodynamic information to establish a severity classification for KD cases.

Qualitative Diagnosis of Solid Breast Mass by Blood Flow in Solid Breast Mass

Breast cancer is one of the most common malignant tumors that seriously endangers women’s physical and mental health and even life-threatening. With the increasing incidence of breast malignant tumors year by year, people are increasingly concerned about the health of female breasts. However, due to the lack of primary prevention methods for breast cancer, the key to improving the cure rate of breast cancer and reducing mortality is early detection, early diagnosis, and early treatment. Hemodynamics embodies the characteristics and laws of the movement of blood and its components in the body. Clinically, monitoring of hemodynamic indicators is usually used to reveal the physiological or pathological changes of the body and understand the development process of the disease. The blood flow in the tumor tissue is high-speed and high-impedance. CDFI can show the distribution of blood flow in the mass. The highest peak velocity (PSV), resistance index (RI) and pulsatility index (PI) of systolic phase can be measured by sampling. This study use contrast-enhanced ultrasound (CEUS) combined with color energy Doppler flow imaging (CDFI) to explore the hemodynamic information of the main blood supply arteries and masses of the breast, analyze the abnormal hemodynamic information of tumors and surrounding tissues, and explore the blood in the breast, the clinical value of hydrodynamics in the qualitative diagnosis of breast masses.

Coherence between Decomposed Components of Wrist and Finger PPG Signals by Imputing Missing Features and Resolving Ambiguous Features

Background: Feature extraction from photoplethysmography (PPG) signals is an essential step to analyze vascular and hemodynamic information. Different morphologies of PPG waveforms from different measurement sites appear. Various phenomena of missing or ambiguous features exist, which limit subsequent signal processing. Methods: The reasons that cause missing or ambiguous features of finger and wrist PPG pulses are analyzed based on the concept of component waves from pulse decomposition. Then, a systematic approach for missing-feature imputation and ambiguous-feature resolution is proposed. Results: From the experimental results, with the imputation and ambiguity resolution technique, features from 35,036 (98.7%) of 35,502 finger PPG cycles and 36307 (99.1%) of 36,652 wrist PPG cycles can be successfully identified. The extracted features became more stable and the standard deviations of their distributions were reduced. Furthermore, significant correlations up to 0.92 were shown between the finger and wrist PPG waveforms regarding the positions and widths of the third to fifth component waves. Conclusion: The proposed missing-feature imputation and ambiguous-feature resolution solve the problems encountered during PPG feature extraction and expand the feature availability for further processing. More intrinsic properties of finger and wrist PPG are revealed. The coherence between the finger and wrist PPG waveforms enhances the applicability of the wrist PPG.

Combining 4D Flow MRI and Complex Networks Theory to Characterize the Hemodynamic Heterogeneity in Dilated and Non-dilated Human Ascending Aortas

Motivated by the evidence that the onset and progression of the aneurysm of the ascending aorta (AAo) is intertwined with an adverse hemodynamic environment, the present study characterized in vivo the hemodynamic spatiotemporal complexity and organization in human aortas, with and without dilated AAo, exploring the relations with clinically relevant hemodynamic and geometric parameters. The Complex Networks (CNs) theory was applied for the first time to 4D flow magnetic resonance imaging (MRI) velocity data of ten patients, five of them presenting with AAo dilation. The time-histories along the cardiac cycle of velocity-based quantities were used to build correlation-based CNs. The CNs approach succeeded in capturing large-scale coherent flow features, delimiting flow separation and recirculation regions. CNs metrics highlighted that an increasing AAo dilation (expressed in terms of the ratio between the maximum AAo and aortic root diameter) disrupts the correlation in forward flow reducing the correlation persistence length, while preserving the spatiotemporal homogeneity of secondary flows. The application of CNs to in vivo 4D MRI data holds promise for a mechanistic understanding of the spatiotemporal complexity and organization of aortic flows, opening possibilities for the integration of in vivo quantitative hemodynamic information into risk stratification and classification criteria.

Myocardial contrast echocardiography assessment of mouse myocardial infarction: comparison of kinetic parameters with conventional methods

This study explores the use of a minimally invasive assessment of myocardial infarction (MI) in mice using myocardial contrast echocardiography (MCE). The technique uses existing equipment and software readily available to the average researcher. C57/BL6 mice were randomized to either MI or sham surgery and evaluated using MCE at 1- or 2-weeks post-surgery. Size-isolated microbubbles were injected via retro-orbital catheter where their non-linear characteristics were utilized to produce the two-dimensional parameters of Wash-in-Rate and the Peak Enhancement, indicative of relative myocardial perfusion and blood volume, respectively. Three-dimensional cardiac reconstructions allowed the calculation of the Percent Agent, interpreted as the vascularity of the entire myocardium. These MCE parameters were compared to conventional assessments including M-Mode, strain analysis, and 2,3,5-Triphenyltetrazolium chloride (TTC) staining. Except for the Wash-in-Rate 2-week cohort, all MCE parameters were able to differentiate sham-operated versus MI animals and correlated with TTC staining (P < 0.05). MCE parameters were also able to identify MI group animals which failed to develop infarctions as determined by TTC staining. This study provides basic validation of these MCE parameters to detect MI in mice complementary to conventional methods while providing additional hemodynamic information in vivo.

Simultaneous fMRI and fast-scan cyclic voltammetry bridges oxygenation and neurotransmitter dynamics across spatiotemporal scales

The vascular contributions of neurotransmitters to the hemodynamic response are gaining more attention in neuroimaging studies, as many neurotransmitters are vasomodulatory. To date, well-established electrochemical techniques that detect neurotransmission in high magnetic field environments are limited. Here, we propose an experimental setting enabling simultaneous fast-scan cyclic voltammetry (FSCV) and blood oxygenation-dependent functional magnetic imaging (BOLD fMRI) to measure both local tissue oxygen and dopamine responses, and global BOLD changes, respectively. By using MR-compatible materials and the proposed data acquisition schemes, FSCV detected physiological analyte concentrations with high spatiotemporal resolution inside of a 9.4 T MRI bore. We found that tissue oxygen and BOLD correlate strongly, and brain regions that encode dopamine amplitude differences can be identified via modeling simultaneously acquired dopamine FSCV and BOLD fMRI time-courses. This technique provides complementary neurochemical and hemodynamic information and expands the scope of studying the influence of local neurotransmitter release over the entire brain.

Advanced Imaging Techniques for Radiotherapy Planning of Gliomas

The accuracy of target delineation in radiation treatment (RT) planning of cerebral gliomas is crucial to achieve high tumor control, while minimizing treatment-related toxicity. Conventional magnetic resonance imaging (MRI), including contrast-enhanced T1-weighted and fluid-attenuated inversion recovery (FLAIR) sequences, represents the current standard imaging modality for target volume delineation of gliomas. However, conventional sequences have limited capability to discriminate treatment-related changes from viable tumors, owing to the low specificity of increased blood-brain barrier permeability and peritumoral edema. Advanced physiology-based MRI techniques, such as MR spectroscopy, diffusion MRI and perfusion MRI, have been developed for the biological characterization of gliomas and may circumvent these limitations, providing additional metabolic, structural, and hemodynamic information for treatment planning and monitoring. Radionuclide imaging techniques, such as positron emission tomography (PET) with amino acid radiopharmaceuticals, are also increasingly used in the workup of primary brain tumors, and their integration in RT planning is being evaluated in specialized centers. This review focuses on the basic principles and clinical results of advanced MRI and PET imaging techniques that have promise as a complement to RT planning of gliomas.

The Effects of Intracranial Stenosis on Cerebral Perfusion and Cognitive Performance

Background: Intracranial stenosis (ICS) may contribute to cognitive dysfunction by decreased cerebral blood flow (CBF) which can be measured quantitatively by arterial spin labelling (ASL). Interpretation of CBF measurements with ASL, however, becomes difficult in patients with vascular disease due to prolonged arterial transit time (ATT). Recently, spatial coefficient of variation (sCoV) of ASL signal has been proposed that approximates ATT and utilized as a proxy marker for assessment of hemodynamic status of cerebral circulation. Objective: We investigate the association of ICS with CBF and sCoV parameters and its eventual effects on cognition in a memory clinic population. Methods: We included 381 patients (mean age = 72.3±7.9 years, women = 53.7%) who underwent 3T MRI and detailed neuropsychological assessment. ICS was defined as≥50% stenosis in any intracranial vessel on 3D Time-of-Flight MR Angiography. Gray matter sCoV and CBF were obtained from 2D EPI pseudo-continuous ASL images. Results: ICS was present in 58 (15.2%) patients. Patients with ICS had higher gray matter sCoV and lower CBF. The association with sCoV remained statistically significant after correction for cardiovascular risk factors. Moreover, ICS was associated with worse performance on visuoconstruction, which attenuated with higher sCoV. Mediation analysis showed that there was an indirect effect of ICS on visuoconstruction via sCoV. Conclusion: These findings suggest that compromised CBF as detected by higher sCoV is related to cognitive impairment among individuals diagnosed with ICS. We also showed that sCoV partially mediates the link between ICS and cognition. Therefore, sCoV may provide valuable hemodynamic information in patients with vascular disease.

Ultrasound Assessment of Extracranial Carotids and Vertebral Arteries in Acute Cerebral Ischemia

Assessing ischemic etiology and mechanism during the acute phase of an ischemic stroke is crucial in order to tailor and monitor appropriate treatment and determine prognosis. Cervical Duplex Ultrasound (CDU) has evolved since many years as an excellent screening tool for the evaluation of extracranial vasculature. CDU has the advantages of a low cost, easily applicable, bed side examination with high temporal and spatial resolution and without exposing the patients to any significant complications. It represents an easily repeatable test that can be performed in the emergency room as a first-line examination of cervical artery pathology. CDU provides well validated estimates of the type of the atherosclerotic plaque, the degree of stenosis, as well as structural and hemodynamic information directly about extracranial vessels (e.g., subclavian steal syndrome) and indirectly about intracranial circulation. CDU may also aid the diagnosis of non-atherosclerotic lesions of vessel walls including dissections, arteritis, carotid-jugular fistulas and fibromuscular dysplasias. The present narrative review outlines all potential applications of CDU in acute stroke management and also highlights its potential therapeutic implications.

An Elusive Prize: Transcutaneous Near InfraRed Spectroscopy (NIRS) Monitoring of the Liver

Introduction: We postulate a relationship between a transcutaneous hepatic NIRS measurement and a directly obtained hepatic vein saturation. If true, hepatic NIRS monitoring (in conjunction with the current dual-site cerebral-renal NIRS paradigm) might increase the sensitivity for detecting shock since regional oxygen delivery changes in the splanchnic circulation before the kidney or brain. We explored a reliable technique for hepatic NIRS monitoring as a prelude to rigorously testing this hypothesis. This proof-of-concept study aimed to validate hepatic NIRS monitoring by comparing hepatic NIRS measurements to direct hepatic vein samples obtained during cardiac catheterization.Method: IRB-approved prospective pilot study of hepatic NIRS monitoring involving 10 patients without liver disease who were already undergoing elective cardiac catheterization. We placed a NIRS monitor on the skin overlying liver during catheterization. Direct measurement of hepatic vein oxygen saturation during the case compared with simultaneous hepatic NIRS measurement.Results: There was no correlation between the Hepatic NIRS values and the directly measured hepatic vein saturation (R = −0.035; P = 0.9238). However, the Hepatic NIRS values correlated with the cardiac output (R = 0.808; P = 0.0047), the systolic arterial blood pressure (R = 0.739; P = 0.0146), and the diastolic arterial blood pressure (R = 0.7548; P = 0.0116).Conclusions: Using the technique described, hepatic NIRS does not correlate well with the hepatic vein saturation. Further optimization of the technique might provide a better measurement. Hepatic NIRS does correlate with cardiac output and thus may still provide a valuable additional piece of hemodynamic information when combined with other non-invasive monitoring.