• droplets
• indicator dilution
• ultrasound contrast agents

• Burroughs Wellcome Fund
• CIHR
• Natural Sciences and Engineering Research Council of Canada

• Heart failure
• Magnetic resonance imaging
• Perfusion
• Prognosis

• Humans
• Male
• Female
• Middle Aged
• Prognosis
• Retrospective Studies
• Aged
• Pulmonary Circulation
• Ventricular Dysfunction/diagnostic imaging
• Ventricular Dysfunction/physiopathology
• Magnetic Resonance Imaging/methods
• Magnetic Resonance Imaging, Cine/methods

• GRS 2539/A/22 Gerencia Regional de Salud de Castilla y León (ES)

• 51Cr red blood cells
• red blood cell survival
• red blood cell volume/mass

• Humans
• Erythrocytes
• Hematologic Diseases/blood
• History, 20th Century
• Chromium Radioisotopes
• History, 21st Century
• Nuclear Medicine/history

• coronary artery disease and stable angina
• ischaemia

• Humans
• Contrast Media/administration & dosage
• Female
• Male
• Middle Aged
• Aged
• Workflow
• Coronary Artery Disease/diagnostic imaging
• Magnetic Resonance Imaging/methods
• Coronary Angiography/methods
• Myocardial Perfusion Imaging/methods
• Gadolinium/administration & dosage

• Research Grant 2023 European Association of Cardiovascular Imaging (EACVI)

• Airports
• Algorithms
• Tomography, X-Ray Computed/methods
• Cone-Beam Computed Tomography/methods
• Phantoms, Imaging
• Image Processing, Computer-Assisted/methods

• arterial input function
• cerebral blood flow
• cerebral blood volume
• dynamic contrast enhanced MRI
• dynamic susceptibility contrast MRI

• HollandPTC-Varian Consortium
• Medical Delta Cancer Diagnostics 3.0

• absolute coronary flow
• coronary flow reserve
• fractional flow reserve
• index of microcirculatory resistance
• microcirculatory reserve ratio
• resistive reserve ratio

• Chronic thromboembolic disease
• Chronic thromboembolic pulmonary hypertension
• Computed tomography pulmonary angiography
• Dynamic contrast enhanced magnetic resonance imaging
• Pulmonary hypertension
• Pulmonary perfusion MRI

• cardiac output index
• computed tomography
• myocardial perfusion imaging
• time-enhancement curve

• Animals
• Cardiac Output
• Heart/diagnostic imaging
• Myocardial Perfusion Imaging/methods
• Retrospective Studies
• Swine
• Tomography, X-Ray Computed/methods

• PET/CT
• dynamic imaging
• kinetic analysis

Blood flow rate in dialysis (vascular) access is the key parameter to examine patency and to evaluate the outcomes of various endovascular interve7ntions. While angiography is extensively used for dialysis access–salvage procedures, to date, there is no image-based blood flow measurement application commercially available in the angiography suite. We aim to calculate the blood flow rate in the dialysis access based on cine-angiographic and fluoroscopic image sequences. In this study, we discuss image-based methods to quantify access blood flow in a flow phantom model. Digital subtraction angiography (DSA) and fluoroscopy were used to acquire images at various sampling rates (DSA—3 and 6 frames/s, fluoroscopy—4 and 10 pulses/s). Flow rates were computed based on two bolus tracking algorithms, peak-to-peak and cross-correlation, and modeled with three curve-fitting functions, gamma variate, lagged normal, and polynomial, to correct errors with transit time measurement. Dye propagation distance and the cross-sectional area were calculated by analyzing the contrast enhancement in the vessel. The calculated flow rates were correlated versus an in-line flow sensor measurement. The cross-correlation algorithm with gamma-variate curve fitting had the best accuracy and least variability in both imaging modes. The absolute percent error (mean ± SEM) of flow quantification in the DSA mode at 6 frames/s was 21.4 ± 1.9%, and in the fluoroscopic mode at 10 pulses/s was 37.4 ± 3.6%. The radiation dose varied linearly with the sampling rate in both imaging modes and was substantially low to invoke any tissue reactions or stochastic effects. The cross-correlation algorithm and gamma-variate curve fitting for DSA acquisition at 6 frames/s had the best correlation with the flow sensor measurements. These findings will be helpful to develop a software-based vascular access flow measurement tool for the angiography suite and to optimize the imaging protocol amenable for computational flow applications.

• blood flow
• bolus tracking algorithm
• curve fitting
• dialysis access
• digital subtraction angiography
• fluoroscopy
• radiation dose

The vascular function of a vessel can be qualitatively and intraoperatively checked by recording the blood dynamics inside the vessel via fluorescence angiography (FA). Although FA is the state of the art in proving the existence of blood flow during interventions such as bypass surgery, it still lacks a quantitative blood flow measurement that could decrease the recurrence rate and postsurgical mortality. Previous approaches show that the measured flow has a significant deviation compared to the gold standard reference (ultrasonic flow meter). In order to systematically address the possible sources of error, we investigated the error in transit time measurement of an indicator. Obtaining in vivo indicator dilution curves with a known ground truth is complex and often not possible. Further, the error in transit time measurement should be quantified and reduced. To tackle both issues, we first computed many diverse indicator dilution curves using an in silico simulation of the indicator's flow. Second, we post-processed these curves to mimic measured signals. Finally, we fitted mathematical models (parabola, gamma variate, local density random walk, and mono-exponential model) to re-continualize the obtained discrete indicator dilution curves and calculate the time delay of two analytical functions. This re-continualization showed an increase in the temporal accuracy up to a sub-sample accuracy. Thereby, the Local Density Random Walk (LDRW) model performed best using the cross-correlation of the first derivative of both indicator curves with a cutting of the data at 40% of the peak intensity. The error in frames depends on the noise level and is for a signal-to-noise ratio (SNR) of 20 dB and a sampling rate of f_s = 60 Hz at fs-1·0.25(±0.18), so this error is smaller than the distance between two consecutive samples. The accurate determination of the transit time and the quantification of the error allow the calculation of the error propagation onto the flow measurement. Both can assist surgeons as an intraoperative quality check and thereby reduce the recurrence rate and post-surgical mortality.

• blood flow velocity
• fluorescence angiography
• indicator dilution curve
• mathematical fits
• sub-frame rate accuracy
• transit time

• DCE–MRI
• Dynamic contrast-enhanced MRI
• MR perfusion imaging
• MR permeability mapping
• Quantitative MRI

• Capillary Permeability/physiology
• Contrast Media/administration & dosage
• Contrast Media/pharmacokinetics
• Extracellular Space/diagnostic imaging
• Extracellular Space/metabolism
• Humans
• Image Enhancement/methods
• Magnetic Resonance Imaging/methods
• Neoplasms/blood supply
• Neoplasms/diagnostic imaging
• Perfusion Imaging/methods
• Regional Blood Flow/physiology

• Gadgetron
• Inline AI
• arterial input function
• deep learning
• myocardial perfusion
• perfusion quantification

• Algorithms
• Deep Learning
• Heart Ventricles/diagnostic imaging
• Humans
• Magnetic Resonance Imaging
• Perfusion

• ZIA HL006242 Intramural NIH HHS
• ZIA HL006214 Intramural NIH HHS
• CH/16/2/32089 British Heart Foundation
• Z99 HL999999 Intramural NIH HHS
• FS/18/21/33447 British Heart Foundation

• cardiovascular
• circulation time
• mortality
• sleep apnea
• sleep-disordered breathing

• Contrast-enhanced ultrasound
• Indicator dilution theory
• Kinetic modeling
• Machine learning
• Molecular ultrasound
• Multiparametric ultrasound
• Quantitative ultrasound
• Spatiotemporal analysis
• Time–intensity curves
• Ultrasound contrast agents

• Animals
• Contrast Media
• Humans
• Kinetics
• Machine Learning
• Microbubbles
• Models, Theoretical
• Ultrasonography/methods

Accurately measuring arterial input function (AIF) is essential for quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). We used the indicator dilution principle to evaluate the accuracy of AIF measured directly from an artery following a low-dose contrast media ultrafast DCE-MRI. In total, 15 patients with biopsy-confirmed localized prostate cancers were recruited. Cardiac MRI (CMRI) and ultrafast DCE-MRI were acquired on a Philips 3 T Ingenia scanner. The AIF was measured at iliac arties following injection of a low-dose (0.015 mmol/kg) gadolinium (Gd) contrast media. The cardiac output (CO) from CMRI (CO_CMRI) was calculated from the difference in ventricular volume at diastole and systole measured on the short axis of heart. The CO from DCE-MRI (CO_DCE) was also calculated from the AIF and dose of the contrast media used. A correlation test and Bland–Altman plot were used to compare CO_CMRI and CO_DCE. The average (±standard deviation [SD]) area under the curve measured directly from local AIF was 0.219 ± 0.07 mM·min. The average (±SD) CO_CMRI and CO_DCE were 6.52 ± 1.47 L/min and 6.88 ± 1.64 L/min, respectively. There was a strong positive correlation (r = 0.82, P < .01) and good agreement between CO_CMRI and CO_DCE. The CO_DCE is consistent with the reference standard CO_CMRI. This indicates that the AIF can be measured accurately from an artery with ultrafast DCE-MRI following injection of a low-dose contrast media.

• arterial input function
• cardiac output
• indicator dilution principle
• low dose DCE-MRI

• environment
• manure
• metabolism
• nitrogen
• ruminant animal
• technique

• CT
• Gas exchange
• Hyperpolarized xenon-129 MRI
• Perfusion
• Ventilation

• dynamic myocardial perfusion computed tomography
• low tube current
• motion adaptive sparsity prior
• regularization
• total variation

• Blood Volume
• Capillaries/physiology
• Contrast Media
• Hemodynamics
• Humans
• Kinetics
• Male
• Middle Aged
• Models, Cardiovascular
• Perfusion
• Porosity

• Norges Forskningsråd
• Norges Forskningsråd (NO)

Diabetes mellitus (DM) is one of the most common diseases worldwide. Uncontrolled and prolonged hyperglycemia can cause diabetic complications, which reduce the quality of life of patients. Diabetic complications are common in DM patients. Because it is impossible to completely recover from diabetic complications, it is important for early detection. In this study, we suggest a novel method of determining blood flow characteristics based on fluorescence image analysis with indocyanine green and report that diabetic complications have unique blood flow characteristics.

We analyzed time-series fluorescence images obtained from controls, DM patients, and DM patients with complications. The images were segmented into the digits and the dorsum of the feet and hands, and each part has been considered as arterial and capillary flow. We compared the blood flow parameters in each region among the three groups.

The DM patients with complications showed similar blood flow parameters to the controls, except the area under the curve and the maximum intensity, which indicate the blood flow volume. These parameters were significantly decreased in DM patients with complications. Although some blood flow parameters in the feet of DM patients with complications were close to normal blood flow, the vascular response of the macrovessels and microvessels to stimulation of the hands was significantly reduced, which indicates less reactivity in DM patients with complications.

Our results suggest that DM patients, and DM patients with complications, have unique peripheral blood flow characteristics.

• Blood flow characteristic
• Diabetes mellitus
• Diabetic complications
• Indocyanine green
• Medical imaging

The authors developed a fully automated framework to quantify myocardial blood flow (MBF) from contrast-enhanced cardiac magnetic resonance (CMR) perfusion imaging and evaluated its diagnostic performance in patients.

Fully quantitative CMR perfusion pixel maps were previously validated with microsphere MBF measurements and showed potential in clinical applications, but the methods required laborious manual processes and were excessively time-consuming.

CMR perfusion imaging was performed on 80 patients with known or suspected coronary artery disease (CAD) and 17 healthy volunteers. Significant CAD was defined by quantitative coronary angiography (QCA) as ≥70% stenosis. Nonsignificant CAD was defined by: 1) QCA as <70% stenosis; or 2) coronary computed tomography angiography as <30% stenosis and a calcium score of 0 in all vessels. Automatically generated MBF maps were compared with manual quantification on healthy volunteers. Diagnostic performance of the automated MBF pixel maps was analyzed on patients using absolute MBF, myocardial perfusion reserve (MPR), and relative measurements of MBF and MPR.

The correlation between automated and manual quantification was excellent (r = 0.96). Stress MBF and MPR in the ischemic zone were lower than those in the remote myocardium in patients with significant CAD (both p < 0.001). Stress MBF and MPR in the remote zone of the patients were lower than those in the normal volunteers (both p < 0.001). All quantitative metrics had good area under the curve (0.864 to 0.926), sensitivity (82.9% to 91.4%), and specificity (75.6% to 91.1%) on per-patient analysis. On a per-vessel analysis of the quantitative metrics, area under the curve (0.837 to 0.864), sensitivity (75.0% to 82.7%), and specificity (71.8% to 80.9%) were good.

Fully quantitative CMR MBF pixel maps can be generated automatically, and the results agree well with manual quantification. These methods can discriminate regional perfusion variations and have high diagnostic performance for detecting significant CAD. (Technical Development of Cardiovascular Magnetic Resonance Imaging; NCT00027170)

• computer-aided diagnosis
• image processing
• magnetic resonance imaging
• myocardial blood flow
• myocardial perfusion
• quantification

• Humans
• Body Fluids/metabolism
• Electric Stimulation
• Leg
• Muscle, Skeletal/physiology
• Sitting Position
• Male
• Middle Aged

• Drug delivery
• Extravasation
• Machine-perfused pig liver
• Sonoporation
• Vessel poration

• Animals
• Contrast Media
• Disease Models, Animal
• Drug Delivery Systems
• Image Enhancement/methods
• Liver/blood supply
• Liver/diagnostic imaging
• Microbubbles/adverse effects
• Microvessels/diagnostic imaging
• Microvessels/injuries
• Swine
• Ultrasonic Waves/adverse effects
• Ultrasonography/methods

• Animals
• Biological Transport
• Contrast Media/pharmacokinetics
• Humans
• Kinetics
• Models, Biological
• Neoplasms/diagnostic imaging
• Neoplasms/metabolism
• Neoplasms/pathology
• Neovascularization, Pathologic/diagnostic imaging
• Neovascularization, Pathologic/metabolism
• Neovascularization, Pathologic/pathology

• dce-mri
• first-pass myocardial perfusion imaging
• arterial input function
• myocardial blood flow estimates
• dual-sequence imaging

• Adult
• Blood Flow Velocity
• Contrast Media/administration & dosage
• Coronary Circulation
• Coronary Vessels/physiology
• Female
• Healthy Volunteers
• Humans
• Image Interpretation, Computer-Assisted/instrumentation
• Image Interpretation, Computer-Assisted/methods
• Magnetic Resonance Imaging/instrumentation
• Magnetic Resonance Imaging/methods
• Male
• Models, Cardiovascular
• Myocardial Perfusion Imaging/instrumentation
• Myocardial Perfusion Imaging/methods
• Nonlinear Dynamics
• Phantoms, Imaging
• Predictive Value of Tests
• Regional Blood Flow
• Young Adult

• Algorithms
• Echocardiography/methods
• Humans
• Pulmonary Circulation/physiology
• Pulse Wave Analysis/methods
• Signal Processing, Computer-Assisted

• R01 HL115103 NHLBI NIH HHS

• FFR
• Myocardial CT perfusion
• beam hardening
• mono-energetic images
• spectral detector CT

• R41 HL144271 NHLBI NIH HHS
• T32 EB007509 NIBIB NIH HHS

• CT Perfusion
• iterative reconstruction
• low dose CT

• R01 EB004070 NIBIB NIH HHS
• R41 HL144271 NHLBI NIH HHS
• T32 EB007509 NIBIB NIH HHS

• blood volume determination
• hematocrit
• hemodilution
• intravascular volume
• intravenous infusions
• mathematical model

Evaluation of blood supply of different organs relies on labeling blood with a suitable tracer. The tracer kinetics is linear: Tracer concentration at an observation site is a linear response to an input somewhere upstream the arterial flow. The corresponding impulse response functions are currently treated empirically without incorporating the relation to the vascular morphology of an organ. In this work we address this relation for the first time. We demonstrate that the form of the response function in the entire arterial tree is reduced to that of individual vessel segments under approximation of good blood mixing at vessel bifurcations. The resulting expression simplifies significantly when the geometric scaling of the vascular tree is taken into account. This suggests a new way to access the vascular morphology in vivo using experimentally determined response functions. However, it is an ill-posed inverse problem as demonstrated by an example using measured arterial spin labeling in large brain arteries. We further analyze transport in individual vessel segments and demonstrate that experimentally accessible tracer concentration in vessel segments depends on the measurement principle. Explicit expressions for the response functions are obtained for the major middle part of the arterial tree in which the blood flow in individual vessel segments can be treated as laminar. When applied to the analysis of regional cerebral blood flow measurements for which the necessary arterial input is evaluated in the carotid arteries, present theory predicts about 20% underestimation, which is in agreement with recent experimental data.

• Blood Flow Velocity/physiology
• Brain/blood supply
• Brain/physiology
• Carotid Arteries/physiology
• Cerebrovascular Circulation/physiology
• Humans
• Kinetics
• Spin Labels

• P01 AG003949 NIA NIH HHS
• 2P01AG003949-26A2 NIA NIH HHS

• Animals
• Antibiotics, Antineoplastic/adverse effects
• Antibiotics, Antineoplastic/pharmacokinetics
• Capillary Permeability/drug effects
• Cardiotoxicity/metabolism
• Cardiotoxicity/physiopathology
• Cardiotoxins/adverse effects
• Cardiotoxins/pharmacokinetics
• Doxorubicin/adverse effects
• Doxorubicin/pharmacokinetics
• Echocardiography/drug effects
• Fluorescence
• Heart/drug effects
• Heart/physiology
• Myocardium/metabolism
• Rats, Inbred F344
• Rats, Sprague-Dawley
• Rats, Wistar
• Ventricular Pressure/drug effects

• R25 GM061347 NIGMS NIH HHS

• myocardial perfusion quantification
• perfusion CMR
• spatial resolution
• voxel-wise

• (170.0170) Medical optics and biotechnology
• (170.3880) Medical and biological imaging
• (170.3890) Medical optics instrumentation
• (170.4580) Optical diagnostics for medicine
• (170.5120) Photoacoustic imaging

Aerobic activity levels increase with body temperature across vertebrates. Differences in these levels, from highly active to sedentary, are reflected in their ecology and behavior. Yet, the changes in the cardiovascular system that allow for greater oxygen supply at higher temperatures, and thus greater aerobic activity, remain unclear. Here we show that the total volume of red blood cells in the body increases exponentially with temperature across vertebrates, after controlling for effects of body size and taxonomy. These changes are accompanied by increases in relative heart mass, an indicator of aerobic activity. The results point to one way vertebrates may increase oxygen supply to meet the demands of greater activity at higher temperatures.

• Aerobic capacity
• Allometry
• Erythrocyte
• Metabolic rate
• Oxygen consumption
• Respiration
• Scaling

• Dynamic CT
• FFR
• absolute blood flow
• myocardial perfusion
• porcine model

• R41 HL144271 NHLBI NIH HHS
• T32 EB007509 NIBIB NIH HHS

• Algorithms
• Contrast Media
• Humans
• Image Processing, Computer-Assisted
• Indicator Dilution Techniques
• Likelihood Functions
• Male
• Models, Biological
• Prostate/diagnostic imaging
• Prostate/physiology
• Prostatic Neoplasms/diagnostic imaging
• Prostatic Neoplasms/physiopathology
• ROC Curve
• Reproducibility of Results
• Ultrasonography/methods

• Blood flow
• Blood volume
• Imaging
• Mean transit time
• Perfusion

The aim. (1) To develop a mathematical model of the passage of a diffusible indicator through microcirculation based on a stochastic description of diffusion and flow; (2) To use Goresky transform of the dilution curves of the diffusible indicators for the estimation of the permeability of a tissue-capillary barrier.

The method. We assume that there are two causes for flow to be stochastic: (a) All microvessels are divided between open and closed microvessels. There exists random exchange between the two groups. (b) The flow through open microvessels is also random. We assume that each diffusing tracer has a probability to leave the intravascular space, and has a probability to return. We also assume that all considered processes are stationary (stability of microcirculation).

Conclusion. (a) The distribution of the time to pass microcirculation by diffusing indicator is given by a compound Poisson distribution; (b) The permeability of tissue-capillary barrier can be obtained from the means, delay, and dispersions of the dilutions of intravascular and diffusing traces.