Estimation Of Blood Flow Research Articles

Cerebral Blood Flow and Arterial Transit Time Variations in Elders with Long COVID

AbstractBackgroundMany COVID‐19 patients experience persistant neurological symptoms that often extend beyond the period of acute infection, referred to as “Long COVID”, where most patients reported brain fog and cognitive dysfunction. While elderly individuals are more vulnerable to possible enduring cognitive impairments after acute COVID‐19 requiring hospitalization, there is increasing concern that older patients with Long COVID will be at high risk for developing Alzheimer’s disease (AD) and dementia. Although there is emerging recognition of Long COVID, its underlying neuropathology remains unknown. This study aimed to investigate neurovascular function using advanced MRI perfusion in elder patients with Long COVID.MethodWell‐matched elderly Long COVID patients (n = 14, mean age = 60.1±4.3 years, 12F, 2M) and control subjects (n = 25, mean age = 60.4±7.2 years, 19F, 6M) underwent neurocognitive testing as well as neuroimaging. Patients were seen 711.57 ± 165.02 days after the initial mild non‐hospitalized COVID‐19 infection. Clinical cognitive complaints of Long COVID patients included memory changes (n = 12, 85.7%), attention (n = 12, 85.7%), speech/writing (n = 9, 64.3%), and multitasking (n = 9, 64.3%). Brain perfusion was evaluated using an advanced 3D pseudo‐continuous arterial spin labeling (pCASL) sequence with Hadamard encoded multiple post‐labeling delays (PLDs), enabling estimation of Cerebral Blood Flow (CBF) and Arterial Transit Time (ATT) ATT and ATT corrected CBF.ResultConventional MRI scans (T1, T2, and FlAIR) appear normal in all subjects. Voxelwise comparisons between Long‐COVID and control subjects showed a significant global decrease in the ATT (p < 0.05, cluster corrected at α < 0.05), along default mode and other key networks, where there is a trend of decreased CBF (p<0.05, uncorrected) specifically in the frontal lobe in those with Long COVID.ConclusionThese preliminary results in an aging group indicate that neurocognitive effects of Long COVID could be attributed to neurovascular dysfunction, even in those cases with initial non‐hospitalized mild COVID‐19 of more than 500 days. The novel finding of diffusely decreased ATT could be something attributable to the unique neurovascular mechanism of Long COVID. Future longitudinal research following the progression of those elderly Long COVID patients with known abnormal neurovascular function to fully evaluate their risk for developing AD and dementia.

Video-based sympathetic arousal assessment via peripheral blood flow estimation.

Electrodermal activity (EDA) is considered a standard marker of sympathetic activity. However, traditional EDA measurement requires electrodes in steady contact with the skin. Can sympathetic arousal be measured using only an optical sensor, such as an RGB camera? This paper presents a novel approach to infer sympathetic arousal by measuring the peripheral blood flow on the face or hand optically. We contribute a self-recorded dataset of 21 participants, comprising synchronized videos of participants' faces and palms and gold-standard EDA and photoplethysmography (PPG) signals. Our results show that we can measure peripheral sympathetic responses that closely correlate with the ground truth EDA. We obtain median correlations of 0.57 to 0.63 between our inferred signals and the ground truth EDA using only videos of the participants' palms or foreheads or PPG signals from the foreheads or fingers. We also show that sympathetic arousal is best inferred from the forehead, finger, or palm.

Photoacoustic vector tomography for deep haemodynamic imaging.

Imaging deep haemodynamics non-invasively remains a quest. Although optical imaging techniques can be used to measure blood flow, they are generally limited to imaging within ∼1 mm below the skin's surface. Here we show that such optical diffusion limit can be broken through by leveraging the spatial heterogeneity of blood and its photoacoustic contrast. Specifically, successive single-shot wide-field photoacoustic images of blood vessels can be used to visualize the frame-to-frame propagation of blood and to estimate blood flow speed and direction pixel-wise. The method, which we named photoacoustic vector tomography (PAVT), allows for the quantification of haemodynamics in veins more than 5 mm deep, as we show for regions in the hands and arms of healthy volunteers. PAVT may offer advantages for the diagnosis and monitoring of vascular diseases and for the mapping of the function of the circulatory system.

The influence of insulin-related genetic variants on fetal growth, fetal blood flow, and placental weight in a prospective pregnancy cohort

The fetal insulin hypothesis proposes that low birthweight and type 2 diabetes (T2D) in adulthood may be two phenotypes of the same genotype. In this study we aimed to explore this theory further by testing the effects of GWAS-identified genetic variants related to insulin release and sensitivity on fetal growth and blood flow from week 20 of gestation to birth and on placental weight at birth. We calculated genetic risk scores (GRS) of first phase insulin release (FPIR), fasting insulin (FI), combined insulin resistance and dyslipidaemia (IR + DLD) and insulin sensitivity (IS) in a study population of 665 genotyped newborns. Two-dimensional ultrasound measurements with estimation of fetal weight and blood flow were carried out at week 20, 25, and 32 of gestation in all 665 pregnancies. Birthweight and placental weight were registered at birth. Associations between the GRSs and fetal growth, blood flow and placental weight were investigated using linear mixed models. The FPIR GRS was directly associated with fetal growth from week 20 to birth, and both the FI GRS, IR + DLD GRS, and IS GRS were associated with placental weight at birth. Our findings indicate that insulin-related genetic variants might primarily affect fetal growth via the placenta.

Abstract 15577: Diagnostic Performance of Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography versus Coronary Angiography Fractional Flow Reserve in Estimating Myocardial Blood Flow and Flow Reserve: A Diagnostic Accuracy Meta-Analysis

Introduction: Precisely estimating myocardial blood flow and flow reserve is crucial in diagnosing and managing ischemic heart disease. Coronary angiography fractional flow reserve (FFR) has been a standard tool. However, the recent emergence of Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography (CZT-SPECT) has provided an innovative diagnostic approach. Consequently, a comprehensive comparative analysis of their efficacies in evaluating myocardial blood flow and flow reserve is necessary. Hypothesis: This study aims to determine the diagnostic accuracy of CZT-SPECT compared to coronary angiography FFR in estimating myocardial blood flow and flow reserve. Methods: A systematic search until July 2022 was conducted across databases such as PubMed, Embase, and Web of Science, focusing on studies comparing CZT-SPECT and coronary angiography FFR in the estimation of myocardial blood flow and flow reserve. Utilizing the mada package in R software (version 4.0.3), we conducted diagnostic accuracy analysis by pooling metrics like sensitivity, specificity, false-positive rate estimates, diagnostic odds ratio, and positive and negative Likelihood Ratios (LR), all of which were presented with a 95% Confidence Interval (CI). Results: The meta-analysis incorporated 6 studies with a total patient population of 346. Our findings reveal that CZT-SPECT exhibited a pooled sensitivity of 79.1% (95% CI: 71.8-84.9%, I^2=0) and a specificity of 78.5% (95% CI: 70.4-84.8%, I^2=25.3%). The false-positive rate was 21.5% (95% CI: 15.2-29.6%). Moreover, CZT-SPECT demonstrated a diagnostic odds ratio of 13.75 (95% CI: 7.67-24.65), while the positive likelihood ratio was 3.67 (95% CI: 2.59-5.19), and the negative likelihood ratio stood at 0.26 (95% CI: 0.19-0.37). Conclusions: This study provides valuable insights into the diagnostic accuracy of CZT-SPECT compared to coronary angiography FFR in estimating myocardial blood flow and flow reserve. These findings indicate that while CZT-SPECT shows promising diagnostic potential, its performance is similar to coronary angiography FFR. The results will be instrumental in informing clinical decision-making and shaping future research directions in the field of cardiovascular imaging.

The effects of nicotine use during adolescence and young adulthood on gray matter cerebral blood flow estimates.

Nicotine and tobacco product (NTP) use remains prevalent in adolescence/young adulthood. The effects of NTPs on markers of brain health during this vulnerable neurodevelopmental period remain largely unknown. This report investigates associations between NTP use and gray matter cerebral blood flow (CBF) in adolescents/young adults. Adolescent/young adult (16-22 years-old) nicotine users (NTP; N = 99; 40 women) and non-users (non-NTP; N = 95; 56 women) underwent neuroimaging sessions including anatomical and optimized pseudo-continuous arterial spin labeling scans. Groups were compared on whole-brain gray matter CBF estimates and their relation to age and sex at birth. Follow-up analyses assessed correlations between identified CBF clusters and NTP recency and dependence measures. Controlling for age and sex, the NTP vs. non-NTP contrast revealed a single cluster that survived thresholding which included portions of bilateral precuneus (voxel-wise alpha < 0.001, cluster-wise alpha < 0.05; ≥7 contiguous voxels). An interaction between NTP group contrast and age was observed in two clusters including regions of the left posterior cingulate (PCC)/lingual gyrus and right anterior cingulate cortex (ACC): non-NTP exhibited positive correlations between CBF and age in these clusters, whereas NTP exhibited negative correlations between CBF and age. Lower CBF from these three clusters correlated with urine cotinine (rs=-0.21 - - 0.16; ps < 0.04) and nicotine dependence severity (rs=-0.16 - - 0.13; ps < 0.07). This is the first investigation of gray matter CBF in adolescent/young adult users of NTPs. The results are consistent with literature on adults showing age- and nicotine-related declines in CBF and identify the precuneus/PCC and ACC as potential key regions subserving the development of nicotine dependence.

Cerebrovascular reactivity to carbon dioxide tension in newborns: data from combined time-resolved near-infrared spectroscopy and diffuse correlation spectroscopy.

Critically ill newborns are at risk of brain damage from cerebrovascular disturbances. A cerebral hemodynamic monitoring system would have the potential role to guide targeted intervention. To obtain, in a population of newborn infants, simultaneous near-infrared spectroscopy (NIRS)-based estimates of cerebral tissue oxygen saturation () and blood flow during variations of carbon dioxide tension () levels within physiologic values up to moderate permissive hypercapnia, and to examine if the derived estimate of metabolic rate of oxygen would stay constant, during the same variations. We enrolled clinically stable mechanically ventilated newborns at postnatal age without brain abnormalities at ultrasound. and blood flow index were measured using a non-invasive device (BabyLux), which combine time-resolved NIRS and diffuse-correlation spectroscopy. The effect of changes in transcutaneous on , cerebral blood flow (CBF), and cerebral metabolic rate of oxygen index () were estimated. Ten babies were enrolled and three were excluded. Median GA at enrollment was 39 weeks and median weight 2720 g. increased 0.58% (95% CI 0.55; 0.61, ), CBF 2% (1.9; 2.3, ), and 0.3% (0.05; 0.46, ) per mmHg increase in . BabyLux device detected -induced changes in cerebral and CBF, as expected. The small statistically significant positive relationship between and variation is not considered clinically relevant and we are inclined to consider it as an artifact.

Growth rate affects blood flow rate to the tibia of the dinosaur Maiasaura

AbstractFossil bones were once living tissues that demanded internal blood perfusion in proportion to their metabolic requirements. Metabolic rates were primarily associated with bone growth (modeling) in the juvenile stages and with alteration and repair of existing bone affected by weight bearing and locomotion (remodeling) in later stages. This study estimates blood flow rates to the tibia shafts of the Late Cretaceous hadrosaurid Maiasaura peeblesorum, based on the size of the primary nutrient foramina in fossil bones. Foramen size quantitatively reflects arterial size and hence blood flow rate. The results showed that the bone metabolic intensity of juveniles (ca. 1 year old) was greater than fourfold higher than that of 6- to 11-year-old adults. This difference is much greater than expected from standard metabolic scaling and is interpreted as a shift from the high metabolic demands for primary bone modeling in the rapidly growing juveniles to a lower metabolic demand of adults to remodel their bones for repair of microfractures accumulated during locomotion and weight bearing. Large nutrient foramina of adults indicate a high level of cursorial locomotion characteristic of tachymetabolic endotherms. The practical value of these results is that juvenile and adult stages should be treated separately in interspecific analyses of bone perfusion in relation to body mass.

Comparison of numerical-integration-based methods for blood flow estimation in diffuse correlation spectroscopy

Background and ObjectiveDiffuse correlation spectroscopy (DCS) is an optical blood flow monitoring technology that has been utilized in various biomedical applications. In signal processing of DCS, nonlinear fitting of the experimental data and the theoretical model can be a hindrance in real-time blood flow monitoring. As one of the approaches to resolve the issue, INISg1, the inverse of numerical integration of squared g1 (a normalized electric field autocorrelation function), that could surpass the state-of-the-art technique at the time in terms of signal processing speed, has been introduced. While it is possible to implement INISg1 using various numerical integration methods, no relevant studies have been performed. Meanwhile, INISg1 was only tested within limited experimental conditions, which cannot guarantee the robustness of INISg1 in various experimental conditions. Thus, this study aims to introduce variants of INISg1 and perform a thorough comparison of the original INISg1 and its variants. MethodsIn this study, based on the right Riemann sum (RR) and trapezoid rule (TR) of numerical integration, INISg1_RR and INISg1_TR are suggested. They are thoroughly compared with the original INISg1 using model-based simulations that offer us control of most of the experimental conditions, including integration time, β, and photon count rate. ResultsExcept for some extreme cases, INISg1 performed more robustly than INISg1_RR and INISg1_TR. However, in extreme conditions, variants of INISg1 performed better than INISg1. With the same condition, the signal processing speed of INISg1 was 1.63 and 1.98 times faster than INISg1_RR and INISg1_TR, respectively. ConclusionThis study shows that INISg1 is robust in most cases and the study can be a guide for researchers using INISg1 and its variants in different types of DCS applications.

Analyzing the Role of Arterial Spin Labelling in Patients Undergoing Endovascular Thrombectomy for Large Vessel Occlusion—a Prospective Single Center Study

Acute stroke is one of the leading causes of death globally. Imaging remains the most common modality to diagnose and predict outcomes in patients with stroke. Conventionally, computed tomography (CT) was the preferred choice; however, imaging has expanded to include newer modalities such as Dynamic Susceptibility Contrast (DSC), Dynamic Contrast-Enhanced MRI (DCE), and Arterial Spin Labelling MRI. An alternative method of assessing perfusion, ASL uses the spins of endogenous water protons as a tracer rather than administering a contrast agent. In this manner, endogenous water in the arterial blood is labelled electromagnetically and employed as a freely diffusible tracer. ASL, as opposed to CT, DSC or DCE, allows estimation of cerebral blood flow without exposure to radiation or the administration of contrast material, which is advantageous for patients with impaired renal function or repetitive perfusion imaging. Thus a prospective study was conducted to explore the use of Arterial Spin Labelling MRI in the setting of acute ischemic stroke in both pre and post-thrombectomy patients. Our study is significant as there are no existing prospective studies comparing the cerebral perfusion measured using ASL with neurological outcomes.

Preclinical validation of the advection diffusion flow estimation method using computational patient specific coronary tree phantoms.

Coronary computed tomography angiography (CCTA) does not allow the quantification of reduced blood flow due to coronary artery disease (CAD). In response, numerical methods based on the CCTA image have been developed to compute coronary blood flow and assess the impact of disease. However to compute blood flow in the coronary arteries, numerical methods require specification of boundary conditions that are difficult to estimate accurately in a patient-specific manner. We describe herein a new noninvasive flow estimation method, called Advection Diffusion Flow Estimation (ADFE), to compute coronary artery flow from CCTA to use as boundary conditions for numerical models of coronary blood flow. ADFE uses image contrast variation along the tree-like structure to estimate flow in each vessel. For validating this method we used patient specific software phantoms on which the transport of contrast was simulated. This controlled validation setting enables a direct comparison between estimated flow and actual flow and a detailed investigation of factors affecting accuracy. A total of 10 CCTA image data sets were processed to extract all necessary information for simulating contrast transport. A spectral element method solver was used for computing the ground truth simulations with high accuracy. On this data set, the ADFE method showed a high correlation coefficient of between estimated flow and the ground truth flow together with an average relative error of only . Comparing the ADFE method with the best method currently available (TAFE) for image-based blood flow estimation, which showed a correlation coefficient of and average error of , it can be concluded that the ADFE method has the potential to significantly improve the quantification of coronary artery blood flow derived from contrast gradients in CCTA images.

Combined early dynamic 18F-FDG PET/CT and conventional whole-body 18F-FDG PET/CT in hepatocellular carcinoma.

To investigate the diagnostic value of early dynamic 18F-FDG PET/CT(ED 18F-FDG PET/CT) combined with conventional whole-body 18F-FDG PET/CT(WB 18F-FDG PET/CT) in hepatocellular carcinoma (HCC), as well as the difference of early dynamic blood flow parameters and maximum standardized uptake value (SUVmax) in HCC patients with/without liver cirrhosis or microvascular invasion (MVI). Twenty-two consecutive patients (mean age 57.8years) with 28 established HCC lesions (mean size 4.5cm) underwent a blood flow study with an 18F-FDG dynamic scan divided into 24 sequences of 5s each and a standard PET/CT scan. On the ED PET/CT study, an experienced PET/CT physician obtained volumes of interest (VOIs) where three blood flow estimates (time to peak [TTP], blood flow [BF], and hepatic perfusion index [HPI]) were calculated. On the WB PET/CT study, a VOI was placed on the fused scan for each HCC and maximum standardized uptake value (SUVmax) was obtained. Comparison of blood flow estimates, SUVmax, and tumor/background ratio (TNR) was performed among HCCs with and without angioinvasion, as well as HCCs in cirrhotic and non-cirrhotic liver. Compared with WB 18F-FDG PET/CT alone, ED combined with WB 18F-FDG PET/CT can significantly increase the detection rate of moderately differentiated and poorly differentiated HCCs (both P < 0.05). HPI was higher in HCCs in patients with liver cirrhosis than those without liver cirrhosis (P = 0.044). There was no significant difference in TTP, BF, SUVmax, or TNR between HCCs in patients with liver cirrhosis and those without liver cirrhosis. There was no significant difference in blood flow estimates or SUVmax in background liver parenchyma between patients with and those without cirrhosis. TTP was shorter in HCCs with MVI than without MVI (P = 0.046). There was no significant difference in BF, HPI, SUVmax, or TNR between HCCs with MVI and without MVI. There was no significant difference in blood flow estimates or SUVmax in background liver parenchyma between patients with and those without MVI. ED combined with WB 18F-FDG PET/CT can significantly increase the detection rate of moderately differentiated and poorly differentiated HCCs. HPI was significantly higher in HCCs in patients with liver cirrhosis than those without liver cirrhosis. TTP was significantly shorter in HCCs with MVI than without MVI.

Impact of Motion Correction tools on reliability and agreement of three software packages for dynamic- perfusion PET/CT processing

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): University of Groningen/University Medical Centre Groningen. Background PET/CT plays an important role in the evaluation of patients with CAD. It allows for non-invasive assessment of coronary function, by means of software based estimations of regional and global myocardial blood flow (MBF) and coronary flow reserve (CFR). However, measurements can differ between software vendors. Also, motion artifacts can impact their reliability. Literature stands that motion can lead to differences up to 500%. In-software motion correction (ISMC) tools are available in some processing software packages, however they rely on different algorithms and their specific role is yet unknown. Recently, an innovative data driven motion correction (DDMC) algorithm was developed, that specifically tracks and corrects for motion prior the reconstruction process. This opens up the possibility of an standardized MC technique. Purpose This study aims to determine the impact of ISMC and DDMC on the reproducibility and agreement of MBF/CFR values between three software packages for dynamic PET processing. It was hypothesized that the use of MC techniques improves agreement/reproducibility in these parameters between vendors. Methods Twenty-three patients categorized as normal after a 13N-ammonia PET/CT examination acquired between July-December 2020 were retrospectively included. Inclusion criteria: no history of CAD, no perfusion defects, normal LV-function and no MACEs and/or relapse at follow up. These criteria were used to prevent possible interference to MBF/CFR values by concomitant CAD. Reconstructions were made without motion correction (NMC), with ISMC and with DDMC. These reconstructions were analyzed in three different software: Corridor 4DM [4DM], Cedars-Sinai QPET [QPET], and SyngoMBF [Syngo]. Clinical data, as well as regional and global values of MBF in rest and stress and CFR were acquired for the final analysis. Paired T-tests, Bland Altman plots and intraclass correlation coefficients were used for statistical analysis. Results Study population consisted of 15(65%) woman, all patients &amp;gt;60 yo, and 21(91%) of adenosine stress (9% regadenoson). The impact of the MC techniques varied between technique, software and region. Differences ranged from −0.12 (QPET DDMC in RCA stress-MBF) to +0.81 (Syngo ISMC in RCA CFR) ml/g/min. QPET proved to be more sensitive to MC, as significant changes in all regional and global stress-MBF and CFR were detected after applying any MC technique (p&amp;lt;0.001). Bland-Altman plots showed heterogeneous results after the use of MC, with some territories improving the Bias and LoA but the opposite in others. Finally, absolute agrement by ICC was predominantly better when using DDMC compared to NMC and ISMC. Only DDMC achieved an ICC &amp;gt;0.9 (excellent) in the RCA CFR. Conclusions The use of DDMC improves the reliability of regional and global stress MBF and CFR in all packages when compared to the use of ISMC or NMC, however, the impact of DDMC is heterogeneous between the packages.

Estimación de la perfusión de hígado e íleon terminal con microesferas coloreadas, comparando asistencias mecánicas circulatorias de flujo continuo y pulsátil

ObjectiveTo estimate blood flow in the small intestine and liver by administration of coloured microspheres in the left atrium, comparing this estimate with continuous flow perfusion and pulsatile flow, in order to confirm or reject hypoperfusion and hypoxia in these organs attributed to loss of pulse amplitude as the cause of Heyde's syndrome. Material and methodTwenty-two minipig pigs of both sexes weighing 29.5±9.6kg were implanted with 11 continuous and 11 pulsatile mechanical circulatory assist devices were implanted in 22 minipig. Haemodynamic and analytic parameter were measured. Liver and terminal ileum blood perfusión was estimated by administration of stained microspheres previus to circulatory support, at 30minutes of full assist and at 30minutes of partial assist. ResultsData were reported as percent of estimated perfusion at baseline. The study was performed by analysis of variance for repeated measures with a significance α of 0.05. In the liver, type of assistance (total or partial), type of pump (continuous or pulsatile) and the interaction between the 2had the following statistical significance: 0.518. 0.364 and 0.237 respectively. In the terminal ileum the results were: 0.264. 0.193 and 0.141.Analytically significant differences were observed in bilirubin level related to the continuous flow pump, as well as pH and urea. ConclusionsWe observed no significant differences in the estimation of perfusion in ileum and liver when comparing continuous flow and pulsatile flow CMA.

RSO2 Measurement Using NIRS for Lower-Limb Blood Flow Monitoring and Estimation of Safe Balloon Occlusion/Deflation Time in Patients with PAS Who Underwent PBOA during CS.

We examined the utility of regional oxygen saturation (rSO2) measurement using near-infrared spectroscopy (NIRS) for monitoring lower-limb blood flow and estimate the safe balloon occlusion/deflation time in patients with PAS who underwent prophylactic balloon occlusion of the abdominal artery (PBOA) during cesarean section (CS). During CS, the NIRS probes were positioned on either of the anterior tibial muscles. rSO2 was measured continuously during balloon occlusion/deflation. A cycle consisted of inflating the aortic balloon for 30 min and deflating it for 5 min. The rSO2 before/during balloon occlusion and after 5 min of balloon deflation were evaluated. Sixty-two lower limbs (fifteen women and data from 31 sessions of balloon inflation/deflation) were evaluated. rSO2 during balloon occlusion was significantly lower than rSO2 before balloon occlusion (57.9% ± 9.6% vs. 80.3% ± 6.0%; p < 0.01). There were no significant differences between rSO2 before balloon occlusion and rSO2 after 5 min of balloon deflation (80.3% ± 6.0% vs. 78.7% ± 6.6%; p = 0.07). Postoperatively, the lower limbs showed no ischemic symptoms. NIRS can assess lower-limb rSO2 during PBOA for PAS in real time to determine ischemia severity, duration, and recovery capacity.

Prognostic Role of Dynamic CZT Imaging in Heart Failure With Preserved Ejection Fraction.

The objective of the study was to evaluate the prognostic role of myocardial flow reserve (MFR) and myocardial blood flow (MBF) estimates obtained with dynamic cadmium-zinc-telluride (CZT) imaging in the development and progression of heart failure with preserved ejection fraction (HFpEF) in patients with nonobstructive coronary artery disease (CAD) during a 12-month follow-up period. A total of 112 patients (70 men; median age of 62.5 [57.0; 69.0] years) with nonobstructive coronary artery disease were enrolled in the study. Dynamic CZT-SPECT, echocardiography, and coronary CT angiography studies were performed baseline. Distribution of patients was performed by adverse events: group 1 comprised patients with adverse outcomes (n = 25), and group 2 comprised those without it (n = 87). Based on receiver operating characteristic analysis, the levels of MFR ≤1.62 (area under the curve [AUС], 0.884; Р < 0.001), stress-MBF ≤1.35 mL/min per gram (AUС, 0.750; Р < 0.001), and NT-proBNP ≥760.5 pg/mL (AUС, 0.764; Р = 0.001) were identified as cutoff values to predict adverse outcomes. Univariate analysis revealed that type 2 diabetes mellitus ( P = 0.044), the levels of MFR ≤1.62 ( P = 0.014), stress-MBF ≤1.35 mL/min per gram ( P = 0.012), NT-proBNP ≥760.5 pg/mL ( P = 0.018), and diastolic dysfunction ( P = 0.009) were potential risk factors for the development and progression of HFpEF. Multivariate analysis demonstrated that the values of NT-proBNP ≥760.5 pg/mL (odds ratio, 1.87; 95% confidence interval, 1.17-3.62; P = 0.027) and MFR ≤1.62 (odds ratio, 2.801; 95% confidence interval, 1.19-6.55; P = 0.018) were independent predictors of adverse outcomes. Our data suggest that reduced MFR ≤1.62 obtained with dynamic CZT imaging and overexpression of NT-proBNP ≥760.5 pg/mL can individuate patients at high risk of development and progression of HFpEF during a 12-month follow-up period, independently of baseline clinical parameters and imaging variables.

Comparison of phase contrast magnetic resonance imaging and scintigraphy for determination of split pulmonary blood flow in children and young adults with congenital heart disease.

Measurement of differential blood flow to the lungs is important to understanding flow dynamics in the setting of congenital heart disease. Split blood flow via the pulmonary arteries guides and demonstrates the effect of interventions. Minimally invasive imaging of pulmonary blood flow can be achieved with scintigraphy or magnetic resonance imaging (MRI). To assess agreement of pulmonary blood flow measurements obtained by scintigraphy and MRI in children and young adults. We performed a retrospective review of patients < 21years of age who had undergone both nuclear medicine pulmonary perfusion scans (Tc-99m MAA) and cardiac MRI examinations from January 2012 to August 2021 at our tertiary pediatric hospital. Patient demographics, medical/surgical information, and estimates of split blood flow by both modalities were recorded. Pearson's correlation coefficient was used to determine the relationship between split blood flow measured by the two examinations. Agreement was calculated using interclass correlation coefficient (ICC) for absolute agreement and Bland-Altman difference analysis. Correlation between split blood flow measured by scintigraphy and MRI using net flow was 0.90 (95% CI: 0.83-0.94, P< 0.001) and the ICC for agreement on split blood flow was 0.90 (95% CI: 0.84-0.94). Mean difference in split blood flow by Bland-Altman analysis was 0.79% with 95% limits of agreement (-11.2 to 12.8%). There is excellent agreement between Tc-99m scintigraphy and phase contrast MRI for quantification of split pulmonary blood flow in children and young adults with congenital heart disease.

Deep-learning-based 3D blood flow reconstruction in transmissive laser speckle imaging.

Transmissive laser speckle imaging (LSI) is useful for monitoring large field-of-view (FOV) blood flow in thick tissues. However, after longer transmissions, the contrast of the transmitted speckle images is more likely to be blurred by multiple scattering, resulting in decreased accuracy and spatial resolution of deep vessels. This study proposes a deep-learning-based strategy for high spatiotemporal resolution three-dimensional (3D) reconstruction from a single transilluminated laser speckle contrast image, providing more structural and functional details without multifocus two-dimensional (2D) imaging or 3D optical imaging with point/line scanning. Based on the correlation transfer equation, a large training dataset is generated by convolving vessel masks with depth-dependent point spread functions (PSF). The UNet and ResNet are used for deblurring and depth estimation. The blood flow in the reconstructed 3D vessels is estimated by a depth-dependent contrast model. The proposed method is evaluated with simulated data and phantom experiments, achieving high-fidelity structural reconstruction with a depth-independent estimation of blood flow. This fast 3D blood flow imaging technique is suitable for real-time monitoring of thick tissue and the diagnosis of vascular diseases.

Blood flow rates to leg bones of extinct birds indicate high levels of cursorial locomotion

AbstractForamina of bones are beginning to yield more information about metabolic rates and activity levels of living and extinct species. This study investigates the relationship between estimated blood flow rate to the femur and body mass among cursorial birds extending back to the Late Cretaceous. Data from fossil foramina are compared with those of extant species, revealing similar scaling relationships for all cursorial birds and supporting crown bird–like terrestrial locomotor activity. Because the perfusion rate in long bones of birds is related to the metabolic cost of microfracture repair due to stresses applied during locomotion, as it is in mammals, this study estimates absolute blood flow rates from sizes of nutrient foramina located on the femur shafts. After differences in body mass and locomotor behaviors are accounted for, femoral bone blood flow rates in extinct species are similar to those of extant cursorial birds. Femoral robustness is generally greater in aquatic flightless birds than in terrestrial flightless and ground-dwelling flighted birds, suggesting that the morphology is shaped by life-history demands. Femoral robustness also increases in larger cursorial bird taxa, probably associated with their weight redistribution following evolutionary loss of the tail, which purportedly constrains femur length, aligns it more horizontally, and necessitates increased robustness in larger species.

Toward accurate cerebral blood flow estimation in mice after accounting for anesthesia.

Purpose: To improve the accuracy of cerebral blood flow (CBF) measurement in mice by accounting for the anesthesia effects. Methods: The dependence of CBF on anesthesia dose and time was investigated by simultaneously measuring respiration rate (RR) and heart rate (HR) under four different anesthetic regimens. Quantitative CBF was measured by a phase-contrast (PC) MRI technique. RR was evaluated with a mouse monitoring system (MouseOX) while HR was determined using an ultrashort-TE MRI sequence. CBF, RR, and HR were recorded dynamically with a temporal resolution of 1min in a total of 19 mice. Linear regression models were used to investigate the relationships among CBF, anesthesia dose, RR, and HR. Results: CBF, RR, and HR all showed a significant dependence on anesthesia dose (p < 0.0001). However, the dose in itself was insufficient to account for the variations in physiological parameters, in that they showed a time-dependent change even for a constant dose. RR and HR together can explain 52.6% of the variations in CBF measurements, which is greater than the amount of variance explained by anesthesia dose (32.4%). Based on the multi-parametric regression results, a model was proposed to correct the anesthesia effects in mouse CBF measurements, specifically . We also reported awake-state CBF in mice to be 142.0 ± 8.8mL/100g/min, which is consistent with the model-predicted value. Conclusion: The accuracy of CBF measurement in mice can be improved by using a correction model that accounts for respiration rate, heart rate, and anesthesia dose.