Quantitative Blood Flow Measurements Research Articles

Differentiation Between High-Grade Glioma and Brain Metastasis Using Cerebral Perfusion-Related Parameters (Cerebral Blood Volume and Cerebral Blood Flow): A Systematic Review and Meta-Analysis of Perfusion-weighted MRI Techniques.

Distinguishing high-grade gliomas (HGGs) from brain metastases (BMs) using perfusion-weighted imaging (PWI) remains challenging. PWI offers quantitative measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV), but optimal PWI parameters for differentiation are unclear. To compare CBF and CBV derived from PWIs in HGGs and BMs, and to identify the most effective PWI parameters and techniques for differentiation. Systematic review and meta-analysis. Twenty-four studies compared CBF and CBV between HGGs (n = 704) and BMs (n = 488). Arterial spin labeling (ASL), dynamic susceptibility contrast (DSC), dynamic contrast-enhanced (DCE), and dynamic susceptibility contrast-enhanced (DSCE) sequences at 1.5 T and 3.0 T. Following the PRISMA guidelines, four major databases were searched from 2000 to 2024 for studies evaluating CBF or CBV using PWI in HGGs and BMs. Standardized mean difference (SMD) with 95% CIs was used. Risk of bias (ROB) and publication bias were assessed, and I2 statistic was used to assess statistical heterogeneity. A P-value<0.05 was considered significant. HGGs showed a significant modest increase in CBF (SMD = 0.37, 95% CI: 0.05-0.69) and CBV (SMD = 0.26, 95% CI: 0.01-0.51) compared with BMs. Subgroup analysis based on region, sequence, ROB, and field strength for CBF (HGGs: 375 and BMs: 222) and CBV (HGGs: 493 and BMs: 378) values were conducted. ASL showed a considerable moderate increase (50% overlapping CI) in CBF for HGGs compared with BMs. However, no significant difference was found between ASL and DSC (P = 0.08). ASL-derived CBF may be more useful than DSC-derived CBF in differentiating HGGs from BMs. This suggests that ASL may be used as an alternative to DSC when contrast medium is contraindicated or when intravenous injection is not feasible. Stage 2.

Abstract WP267: The Impact of Anesthetic Agents on Regional Cerebral Blood Flow During Carotid Artery Clamping in Patients With Debranching Thoracic Endovascular Aortic Repair and Carotid Endarterectomy

Background: Carotid endarterectomy (CEA) and debranching thoracic endovascular aortic repair (debranching TEVAR) would lead to the reduction of cerebral blood flow (CBF) during carotid artery clamping. Intravenous anesthetics decrease CBF more than volatile anesthetics and may exacerbate cerebral hypoperfusion during carotid artery clamping. We have developed an innovative quantitative measure of regional cerebral blood flow (rCBF) that can be performed at the bedside using near-infrared spectroscopy (NIRS). Using this technique, we measured rCBF during CEA and TEVAR to determine the optimal anesthetic for carotid artery clamping. Methods: Patients undergoing debranching TEVAR and CEA were enrolled. We used NIRS and intravenous injection of Indocyanine green (ICG) to measure rCBF before carotid artery clamping, 10 minutes after clamping, and after de-clamping. The rCBF was calculated by Fick’s principle, using the maximum gradient model that combines the peak values and change in arterial blood concentration of ICG in the brain tissue. We evaluated the effects of each anesthetic (intravenous and volatile) on the rCBF of the cross-clamp side of the carotid artery. Results: The results of the intermediate analysis are shown below. Thirty-two patients who underwent debranching TEVAR and twenty-six who underwent CEA were enrolled. In patients who underwent debranching TEVAR, the rCBF increased from 48.4 to 53.5 ml/min/100g in patients anesthetized with volatile anesthetics and decreased from 55.1 to 32.8 ml/min/100g in patients anesthetized with intravenous anesthetics, as shown in the Figure. There was a significant difference between both anesthetics (p=0.034) but no significant difference between both anesthetics with CEA (p=0.93). Conclusion: In patients undergoing debranching TEVAR, volatile anesthetics may be preferable to intravenous anesthetics during carotid clamping.

Non-invasive low-cost deep tissue blood flow measurement with integrated Diffuse Speckle Contrast Spectroscopy.

Diffuse Correlation Spectroscopy (DCS) is a widely used non-invasive measurement technique to quantitatively measure deep tissue blood flow. Conventional implementations of DCS use expensive single photon counters as detecting elements and optical probes with bulky fiber optic cables. In recent years, newer approaches to blood flow measurement such as Diffuse Speckle Contrast Analysis (DSCA) and Speckle Contrast Optical Spectroscopy (SCOS), have adapted speckle contrast analysis methods to simplify deep tissue blood flow measurements using cameras and single photon counting avalanche detector arrays as detectors. Here, we introduce and demonstrate integrated Diffuse Speckle Contrast Spectroscopy (iDSCS), a novel optical sensor setup which leverages diffuse speckle contrast analysis for probe-level quantitative measurement of tissue blood flow. iDSCS uses a standard photodiode configured in photovoltaic mode to integrate photon intensity fluctuations over multiple integration durations using a custom electronic circuit, as opposed to the high frequency sampling of photon counts with DCS. We show that the iDSCS device is sensitive to deep-tissue blood flow measurements with experiments on a human forearm and compare the sensitivity and dynamic range of the device to a conventional DCS instrument. The iDSCS device features a low-cost, low-power, small form factor instrument design that will enable wireless probe-level measurements of deep tissue blood flow.

Integrated myocardial flow reserve (iMFR) assessment: optimized PET blood flow quantification for diagnosis of coronary artery disease.

Distinguishing obstructive epicardial coronary artery disease (CAD) from microvascular dysfunction and diffuse atherosclerosis would be of immense benefit clinically. However, quantitative measures of absolute myocardial blood flow (MBF) integrate the effects of focal epicardial stenosis, diffuse atherosclerosis, and microvascular dysfunction. In this study, MFR and relative perfusion quantification were combined to create integrated MFR (iMFR) which was evaluated using data from a large clinical registry and an international multi-center trial and validated against invasive coronary angiography (ICA). This study included 1,044 clinical patients referred for 82Rb rest/stress positron emission tomography myocardial perfusion imaging and ICA, along with 231 patients from the Flurpiridaz 301 trial (clinicaltrials.gov NCT01347710). MFR and relative perfusion quantification were combined to create an iMFR map. The incremental value of iMFR was evaluated for diagnosis of obstructive stenosis, adjusted for patient demographics and pre-test probability of CAD. Models for high-risk anatomy (left main or three-vessel disease) were also constructed. iMFR parameters of focally impaired perfusion resulted in best fitting diagnostic models. Receiver-operating characteristic analysis showed a slight improvement compared to standard quantitative perfusion approaches (AUC 0.824 vs. 0.809). Focally impaired perfusion was also associated with high-risk CAD anatomy (OR 1.40 for extent, and OR 2.40 for decreasing mean MFR). Diffusely impaired perfusion was associated with lower likelihood of obstructive CAD, and, in the absence of transient ischemic dilation (TID), with lower likelihood of high-risk CAD anatomy. Focally impaired perfusion extent derived from iMFR assessment is a powerful incremental predictor of obstructive CAD while diffusely impaired perfusion extent can help rule out obstructive and high-risk CAD in the absence of TID.

Quantitative hemodynamic imaging: a method to correct the effects of optical properties on laser speckle imaging.

Studying cerebral hemodynamics may provide diagnostic information on neurological conditions. Wide-field imaging techniques, such as laser speckle imaging (LSI) and optical intrinsic signal imaging, are commonly used to study cerebral hemodynamics. However, they often do not account appropriately for the optical properties of the brain that can vary among subjects and even during a single measurement. Here, we describe the combination of LSI and spatial-frequency domain imaging (SFDI) into a wide-field quantitative hemodynamic imaging (QHI) system that can correct the effects of optical properties on LSI measurements to achieve a quantitative measurement of cerebral blood flow (CBF). We describe the design, fabrication, and testing of QHI. The QHI hardware combines LSI and SFDI with spatial and temporal synchronization. We characterized system sensitivity, accuracy, and precision with tissue-mimicking phantoms. With SFDI optical property measurements, we describe a method derived from dynamic light scattering to obtain absolute CBF values from LSI and SFDI measurements. We illustrate the potential benefits of absolute CBF measurements in resting-state and dynamic experiments. QHI achieved a 50-Hz raw acquisition frame rate with a field of view and flow sensitivity up to . The extracted SFDI optical properties agreed well with a commercial system (). The system showed high stability with low coefficients of variations over multiple sessions within the same day () and over multiple days (). When optical properties were considered, the in-vivo hypercapnia gas challenge showed a slight difference in CBF ( to 0.5% difference). The in-vivo resting-state experiment showed a change in CBF ranking for nine out of 13 animals when the correction method was applied to LSI CBF measurements. We developed a wide-field QHI system to account for the confounding effects of optical properties on CBF LSI measurements using the information obtained from SFDI.

Assessment of the Microcirculation in Superficial and Deep Biotissue with Photobiomodulation

Background Quantitative measurement of blood flow in specific biotissue targets is crucial for photobiomodulation therapy (PBMT). PBMT has been applied on many clinical applications. However, the conclusive confirmation of its effects on microcirculation and laser wavelength dependency in superficial and deep tissues is lacking. Objective This study examines the microcirculatory response and laser wavelength dependency of red and near infrared (NIR) lasers in biotissue. Laser Doppler flowmetry (LDF) was used to assess the flux and velocity of erythrocytes in buccal tissue when exposed to 660 nm and 830 nm laser radiation. Discussion The microcirculatory response of subjects during and after laser radiation were analyzed. Each laser has an energy density of 73.17 J/cm2 . Both the 660 nm and 830 nm lasers demonstrated the capability to enhance microcirculation in both superficial and deep tissues. Furthermore, we observed that laser wavelengths at 660 nm and 830 nm respectively enhanced the microcirculatory response in superficial and deep tissues. Importantly, this cumulative effect persisted for at least 10 minutes. Conclusions The present results indicate that PBM can effectively improve local blood perfusion in specific target areas and peripheral biotissues. These findings have potential applications in enhancing wound healing and local microcirculation within the target areas.

Extracardiac findings with increased perfusion during clinical O-15-H2O PET/CT myocardial perfusion imaging: A case series

BackgroundCoincidental extracardiac findings with increased perfusion were reported during myocardial perfusion imaging (MPI) with various retention radiotracers. Clinical parametric O-15-H2O PET MPI yielding quantitative measures of myocardial blood flow (MBF) was recently implemented at our facility. We aim to explore whether similar extracardiac findings are observed using O-15-H2O. Methods and resultsAll patients (2963) were scanned with O-15-H2O PET MPI according to international guidelines and extracardiac findings were collected. In contrast to parametric O-15-H2O MBF images, extracardiac perfusion was assessed using summed images. Biopsy histopathology and other imaging modalities served as reference standards. Various malignant lesions with increased perfusion were detected, including lymphomas, large-celled neuroendocrine tumour, breast, and lung cancer plus metastases from colonic and renal cell carcinomas. Furthermore, inflammatory and hyperplastic benign conditions with increased perfusion were observed: rib fractures, gynecomastia, atelectasis, sarcoidosis, pneumonia, chronic lung inflammation and fibrosis, benign lung nodule, chronic diffuse lung infiltrates, pleural plaques and COVID-19 infiltrates. ConclusionsMalignant and benign extracardiac coincidental findings with increased perfusion are readily visible and frequently seen on O-15-H2O PET MPI. We recommend evaluating the summed O-15-H2O PET images in addition to the low-dose CT attenuation images.

Time–frequency analysis of laser speckle contrast for transcranial assessment of cerebral blood flow

Improving noninvasive approaches to monitoring blood microcirculation is an urgent topic in modern biomedical engineering. One of the actively developing methods is laser speckle contrast imaging (LSCI), which allows not only the visualization of microvessels but also the quantitative measurements of microcirculatory blood flow. This work shows the application of LSCI for mapping the cerebral vessels of a laboratory animal, and also presents the time–frequency processing of the registered signal. Thus, we expand the capabilities of the existing LSCI approach and demonstrate spatial mapping of blood flow rhythms. The proposed technology makes it possible not only to measure the relative cerebral blood flow but also to expand diagnostic capabilities for a detailed analysis of the physiological mechanisms of changes in blood flow.

Long-Term Prognostic Value of 82Rb PET/CT-Determined Myocardial Perfusion and Flow Reserve in Cancer Patients.

Myocardial flow reserve (MFR), derived from quantitative measurements of myocardial blood flow during PET imaging, provides prognostic information on patients with coronary artery disease (CAD), but it is not known if this also applies to cancer patients with a competing risk for mortality. Methods: To determine the prognostic value of MFR in patients with cancer, we designed a retrospective cohort study comprising 221 patients with known or suspected CAD (median age, 71 y; range, 41-92 y) enrolled between June 2009 and January 2011. Most patients were referred for perioperative risk assessment. Patients underwent measurement of myocardial blood flow at rest and during pharmacologic stress, using quantitative 82Rb PET imaging. They were divided into early-stage versus advanced-stage cancer groups based on cancer histopathology and clinical state and were further stratified by myocardial perfusion summed stress score, summed difference score, and calculated MFR. Overall survival (OS) was assessed using the Kaplan-Meier estimator, and Cox proportional-hazards regression helped identify independent predictors for OS. Results: During a follow-up of 85.6 mo, 120 deaths occurred. MFR, summed difference score, and cancer stage were significantly associated with OS. In the age-adjusted Cox hazard multivariable analysis, MFR and cancer stage remained independent prognostic factors. MFR combined with cancer stage enhanced OS discrimination. The groups had significantly different outcomes (P < 0.001), with 5-y OS of 88% (MFR ≥ 1.97 and early-stage), 53% (MFR < 1.97 and early-stage), 33% (MFR ≥ 1.97 and advanced-stage), and 13% (MFR < 1.97 and advanced-stage). Conclusion: Independent of cancer stage, MFR derived from quantitative PET was prognostic of OS in our cohort of cancer patients with known or suspected CAD. Combining these 2 parameters enhanced discrimination of OS, suggesting that MFR improves risk stratification and may serve as a treatment target to increase survival in cancer patients.

Obstructive sleep apnea, myocardial perfusion and myocardial blood flow: A study of older male twins.

Obstructive sleep apnea (OSA) has been associated with incidence of cardiovascular disease and with nocturnal angina, but evidence of a link with coronary atherosclerosis and myocardial ischemia is limited and previous studies may have been affected by selection bias or unmeasured confounding factors. We performed overnight polysomnography in 178 older male twins. The Apnea/Hypopnea Index (AHI) was calculated to assess OSA from the overnight sleep evaluation. AHI ≥15 was used as indicator of moderate/severe OSA. The following day, twins underwent myocardial perfusion imaging with [82Rb]-chloride positron emission tomography. Quantitative and semiquantitative measures of myocardial perfusion and absolute myocardial blood flow were obtained. The mean age was 68 years and 40% of the sample had an AHI≥15, which indicates moderate to severe OSA. Abnormal myocardial perfusion, both with stress and at rest, was more common in twins with elevated AHI. After adjusting for clinical, lifestyle and behavioral factors, and previous history of cardiovascular disease, twins with AHI ≥15 had 3.6 higher odds (95% CI, 1.5-8.9) of an abnormal total severity score, defined as a score ≥100, and for each 5-point increment in AHI, the odds of abnormality increased by 20% (95% CI, 7%-34%). Twin pairs where both twins had OSA exhibited the greatest risk. There were no differences in measures of ischemia and absolute myocardial blood flow and flow reserve by AHI status. OSA is associated with myocardial perfusion abnormalities that suggest prior subclinical myocardial scarring or infarction. Early environmental factors that affect both twins equally may play a role and should be further explored.

Abstract 15103: Stratifying Coronary Artery Disease (CAD) GWAS Loci Using Cardiac Perfusion Positron Emission Tomography to Identify Loci for Coronary Microvascular Disease

Introduction: Coronary Microvascular Disease (CMVD), defined as disease of the coronary pre-arterioles, arterioles, and capillaries, accounts for 30-50% of the burden of Ischemic Heart Disease (IHD). CAD GWAS studies have identified more than 235 loci, however, the populations enrolled represent heterogeneous IHD with inclusion criteria that include ischemia without confirmation of obstructive CAD (Ischemia with non-obstructed Coronary Arteries). Hypothesis: We hypothesize that CAD GWAS studies are really IHD GWAS studies and a subset of patients enrolled have CMVD as the etiology of their ischemia. Thus several CAD GWAS loci may be CMVD loci. Here we use quantitative measures of myocardial blood flow (MBF) and MBF reserve (MBFR) from cardiac Perfusion PET studies to stratify known CAD loci for CMVD. Methods: We performed a genomic association study for 235 known CAD loci in 383 samples of European (EUR) and 539 samples of African ancestry (AFR) in the Penn Medicine Biobank using clinical Rubidium-82 PET using REGENIE software. Models were adjusted for age, sex, age 2 , age x sex, 5 principal components, and batch corresponding to phenotype extraction. We examined regions within 250kb of known CAD loci for association with PET-derived MBF and MBFR. Bonferroni corrected P-value &lt; 2.13e-4 was considered significant. Results: We found 40 loci in patients of AFR ancestry and 11 CAD loci in patients of EUR ancestry that were significantly associated with MBFR, including several genes which are known to play a role in microvasculature function and angiogenesis (VEGFa, FLT1, and FGF1). Stress MBF values have been shown to reflect epicardial CAD. We found 28 loci in patients of AFR ancestry and 12 loci in patients of EUR ancestry which were significantly associated with stress MBF and are mostly distinct from loci associated with MBFR. One notable exception is PRDM16 which was highly significant in both phenotypes. Conclusions: Our study sub-stratified variants previously associated with CAD to identify those that may be involved in CMVD. Several genes known to be involved in microvasculature function (VEGFa, FLT1, and FGF1) were putative CMVD genes. PRDM16 was associated with stress MBF and MBFR. This work prioritizes CAD loci for further study of mechanisms of CMVD.

Improving Detection of CAD and Prognosis with PET/CT Quantitative Absolute Myocardial Blood Flow Measurements.

The purpose of this review is to provide an overview of the role of PET MPI in the detection of CAD, focussing on the added value of MBF for diagnosis and prognostication. Positron emission tomography (PET) myocardial perfusion imaging (MPI) is increasingly used for the risk stratification of patients with suspected or established coronary artery disease (CAD). PET MPI provides accurate and reproducible non-invasive quantification of myocardial blood flow (MBF) at rest and during hyperemia, providing incremental information over conventional myocardial perfusion alone. Inclusion of MBF in PET MPI interpretation improves both its sensitivity and specificity. Moreover, quantitative MBF measurements have repeatedly been shown to offer incremental and independent prognostic information over conventional clinical markers in a broad range of conditions, including in CAD. Quantitative MBF measurement is now an established and powerful tool enabling accurate risk stratification and guiding patients' management. The role of PET MPI and flow quantification in cardiac allograft vasculopathy (CAV), which represents a particular form of CAD, will also be reviewed.

Single-shot temporal speckle correlation imaging using rolling shutter image sensors

We propose a single-shot wide-field imaging method that maps local temporal intensity decorrelations of dynamic speckle fields. Our method, named rolling shutter speckle imaging (RSSI), utilizes short time intervals between each row of a rolling shutter complementary metal–oxide–semiconductor (RS-CMOS) image sensor to discern fast temporal changes in the speckle field, which otherwise requires sequential measurements with high-speed cameras. RSSI generates elongated speckle patterns on an RS-CMOS image sensor and quantifies temporal decorrelations of speckle fields from row-by-row intensity correlations (RICs) within a single image. To quantify the local speckle decorrelation times of dynamic scattering media, we derived a theoretical model for RIC and verified the model using numerical simulations and flow-phantom experiments. Further, our in vivo imaging results show that RSSI can map the flow rate distributions in cerebral blood vessels with the correction of static scattering in the tissue, demonstrating that RSSI is a powerful and cost-effective imaging tool for in vivo quantitative blood flow measurements.

Influence of Respiration on Collateral Flow in the Fontan Population Using Real-time Phase-contrast Cardiovascular Magnetic Resonance: Collateral Flow Does Not Protect the Ventricle From Volume Deficiency and Diastolic Dysfunction.

The clinical significance of collateral flow for the ventricular function of patients with univentricular hearts is often debated. This study evaluates the impact of collateral flow on respiration-dependent preload modification and diastolic function in Fontan patients assessed by systemic and pulmonary vein (PV) flow patterns. Real-time phase-contrast cardiovascular magnetic resonance was performed in the right upper PV, ascending aorta, superior, and inferior vena cava (IVC) in 21 Fontan patients and 11 healthy individuals. The patients' respiratory cycle was divided into 4 periods to generate respiratory-dependent stroke volumes (SV i ). Conventional quantitative blood flow measurements were used to quantify and differentiate between low (group A) and high (group B) collateral flow. Group B showed significantly lower SV i IVC in inspiration, end-inspiration, expiration, and SV i ΔIVC compared with group A (23.6±4.8mL/m 2 to 33.4±8.0; P =0.005). PV flow resulted in a lower mean SV i PV (11.6±7.6mL/m 2 , vs. 14.0±11.4mL/m 2 ) as well as a significantly lower peak systolic S-wave velocity (S max ) ( P =0.005), S/D-ratio (S max /peak diastolic wave velocity) ( P =0.015), and shorter diastolic deceleration time (DT D ; P =0.030; median DT D =134ms) compared with group A (DT D =202ms). This study demonstrates the incapability of Fontan patients to properly increase preload by inspiration in the presence of significant collateral flow. The results further show that collateral flow is associated with a volume-deprived ventricle and impaired diastolic function.

Prognostic implications of cardiac 82-rubidium positron emission tomography in angina patients with no perfusion defects

Abstract Background Myocardial perfusion imaging with 82-Rubidium positron emission tomography (82Rb-PET) is increasingly used in the assessment of stable coronary artery disease (CAD). Among other variables, it provides quantitative measures of myocardial blood flow (MBF) which has shown the prognostic significance of coronary microvascular dysfunction (CMD), also in patients without perfusion defects. However, other 82Rb-PET variables may also be of prognostic significance in these patients. Purpose The purpose of this study was to evaluate the prognostic value of 82Rb-PET in patients with symptoms suggestive of CAD but no perfusion defects. Methods A study was conducted with 3726 consecutive patients who underwent 82Rb-PET on the suspicion of stable CAD between January 2018 and August 2020. After exclusion of patients with regional perfusion defects, we examined the association of 82Rb-PET derived parameters with a composite endpoint: all-cause mortality, hospitalization for unstable angina pectoris, acute myocardial infarction, heart failure or ischemic stroke in 2175 patients. CMD was defined as myocardial blood flow reserve (MBFR) &amp;lt;2. Analyses were further stratified to assess differences across gender. Results Resting and stress MBF were higher in women, while MBFR was lower and CMD more prevalent (30.5% among women versus 25.3% among men, p=0.008). Over a median follow-up of 1.7 years (IQR 1.1–2.5 years) a total of 148 events were observed. In unadjusted analyses, MBF during stress, MBFR, left ventricular ejection fraction (LVEF), LVEF-reserve, heart rate reserve and Ca-score were associated with adverse outcomes in both genders (Figure 1). A joint multivariable Cox model, for both genders, adjusted for patient characteristics, cardiovascular risk factors and 82Rb-PET variables showed reduced MBFR &amp;lt;2 (HR 1.75, 95% CI 1.24–2.48), resting LVEF (HR 1.38 per 10% decrease, 95% CI 1.24–1.54) and LVEF-reserve (HR 1.19 per 5% decrease, 95% CI 1.07–1.31) to be significant predictors of outcomes (Figure 2). Results were consistent in subgroups defined by gender, previous history of ischemic heart disease (IHD), reduced LVEF and atrial fibrillation. Conclusion MBFR, LVEF and LVEF-reserve derived from 82Rb-PET are predictors of adverse outcome and provide prognostic information in patients with no perfusion defects. This may aid in identifying patients at risk and provide opportunity of prevention. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Department of Cardiology, Bispebjerg Frederiksberg Hospital, Copenhagen

Quantitative regional cerebral blood flow measurement using near-infrared spectroscopy and indocyanine green in patients undergoing superficial temporal to middle cerebral artery bypass for moyamoya disease: a novel method using a frequency filter.

Measuring regional cerebral blood flow (rCBF) after revascularization for moyamoya disease, as a type of ischemic cerebrovascular disease, is crucial. This study aims to validate our novel technology that combines near-infrared spectroscopy (NIRS) with a frequency filter to extract the arterial component. We measured rCBF before and after revascularization for moyamoya disease and at the end of the surgery using NIRO-200NX (Hamamatsu Photonics, Japan) and indocyanine green (ICG). rCBF was calculated using Fick's principle, change in arterial ICG concentrations, and maximum arterial ICG concentration. rCBF measured with NIRS (rCBF_N) was compared with pre- and postoperative rCBF measured with SPECT (rCBF_S). Thirty-four procedures were analyzed. rCBF_N increased from baseline to end of the surgery (mean difference (MD), 2.99ml/min/100g; 95% confidence interval (CI), 0.40-5.57ml/min/100g on the diseased side; MD, 4.94ml/min/100g; 95% CI, 2.35-7.52ml/min/100g on the non-diseased side). Similar trends were observed for rCBF_S (MD, 3.98ml/min/100g; 95% CI, 2.30-5.67ml/min/100g on the diseased side; MD, 2.77ml/min/100g; 95% CI, 1.09-4.45ml/min/100g on the non-diseased side). Intraclass correlations 3 (ICC3s) between rCBF_N and rCBF_S were weak on the diseased side (ICC3, 0.25; 95% CI, -0.03-0.5; p = 0.07) and the non-diseased side (ICC3, 0.24; 95% CI, -0.05-0.5; p = 0.08). rCBF measurements based on this novel method were weakly correlated with rCBF measurements with SPECT.

Acute effect of resistance exercise at different velocities on stiffness and vascularity of the biceps brachii muscle: a preliminary study.

Resistance exercise can be defined as the percentage of maximal strength (%1 repetition maximum) used for a particular exercise. Shear wave elastography (SWE) is a robust and novelty imaging technique that provides information regarding tissue stiffness. Superb microvascular imaging (SMI) is a non-irradiating technique that can provide quantitative measurement of muscle blood flow non-invasively. To compare the acute effects of low- and high-velocity resistance exercise on stiffness and blood flow in the biceps brachii muscle (BBM) using SWE and SMI. This prospective study included 60 healthy men (mean age=28.9 years; age range=26-34 years). BBM stiffness was measured by using SWE at rest, after low- and high-velocity resistance exercise, and muscle blood flow was also evaluated by SMI. Resistance exercise was performed using a dumbbell with a mass adjusted to 70%-80% of one-repetition maximum. The stiffness values increased significantly from resting to high- and low-velocity resistance exercises. There was no significant difference between the elastography values of the BBM after the high- and low-velocity resistance exercise. The blood flow increased significantly from resting to high- and low-velocity resistance exercises. Blood flow increase after low-velocity exercise was significantly higher compared to high-velocity exercise. While muscle stiffness parameters and blood flow significantly increased from resting after both high- and low-velocity resistance exercises, blood flow significantly increased after low-velocity exercise compared to high-velocity exercise. This can mean that metabolic stress, an important trigger for muscle development, is more likely to occur in low-velocity exercise.

Pseudocontinuous Arterial Spin Labeling: Clinical Applications and Usefulness in Head and Neck Entities.

Simple SummaryConventional imaging methods, such as ultrasonography, computed tomography, and magnetic resonance imaging may be inadequate to accurately diagnose lesions of the head and neck because they vary widely. Recently, the arterial spin labeling technique, especially pseudocontinuous arterial spin labeling (pCASL) with the three-dimensional (3D) readout method, has been dramatically developed to improve diagnostic performance for lesion differentiation, which can show prominent blood flow characteristics. Here, we demonstrate the clinical usefulness of 3D pCASL for diagnosing various entities, including inflammatory lesions, hypervascular lesions, and neoplasms in the head and neck, for evaluating squamous cell carcinoma (SCC) treatment responses, and for predicting SCC prognosis.As functional magnetic resonance imaging, arterial spin labeling (ASL) techniques have been developed to provide quantitative tissue blood flow measurements, which can improve the performance of lesion diagnosis. ASL does not require contrast agents, thus, it can be applied to a variety of patients regardless of renal impairments and contrast agent allergic reactions. The clinical implementation of head and neck lesions is limited, although, in recent years, ASL has been increasingly utilized in brain lesions. Here, we review the development of the ASL techniques, including pseudocontinuous ASL (pCASL). We compare readout methods between three-dimensional (3D) turbo spin-echo and 2D echo planar pCASL for the clinical applications of pCASL to head and neck lesions. We demonstrate the clinical usefulness of 3D pCASL for diagnosing various entities, including inflammatory lesions, hypervascular lesions, and neoplasms; for evaluating squamous cell carcinoma (SCC) treatment responses, and for predicting SCC prognosis.

Diagnostic efficiency and incremental value of myocardial blood flow quantification by CZT SPECT for patients with coronary artery disease

Objective: To investigate the diagnostic efficiency and incremental value of quantitative myocardial blood flow measurements by Cadmium-Zine-Telluride (CZT) single photon emission computed tomography (SPECT) dynamic myocardial perfusion imaging (MPI) in patients with coronary artery disease (CAD) compared with traditional semi-quantitative measurements by MPI. Methods: This is a retrospective, cross-sectional study. We retrospectively analyzed clinical data of patients with suspected or known CAD, who underwent the dynamic MPI quantitative blood flow measurement of CZT SPECT in TEDA International Cardiovascular Hospital from October 2018 to December 2020. Clinical data, semi-quantitative parameters (stress score (SS), rest score (RS) and different score (DS)) and myocardial quantitative blood flow parameters (rest myocardial blood flow (rMBF), stress myocardial blood flow (sMBF) and myocardial flow reserve (MFR)) were analyzed. According to the results of coronary angiography, patients were divided into the stenosis group and the control group with coronary artery stenosis ≥50% or ≥75% as the diagnosis criteria. The differences of quantitative and semi-quantitative parameters between the two groups were compared, and the diagnostic efficacy was compared by receiver operating characteristic(ROC) curve. Results: A total of 98 patients with a mean age of (62.1±8.7) years were included in the study, including 66 males (67%). At the patient level, with the positive standard of coronary artery stenosis≥50%, the left ventricle (LV) stress MBF (LV-sMBF) ((1.36±0.45) ml·min-1·g-1) and LV-MFR (1.45±0.43) of the stenosis group were lower than the LV-sMBF ((2.09±0.64) ml·min-1·g-1) and LV-MFR (2.17±0.54) of control group; summed SS and summed DS were higher than control group (all P<0.05). With the positive standard of coronary artery stenosis ≥75%, the LV-sMBF ((1.19±0.34) ml·min-1·g-1) and LV-MFR (1.34±0.35) of stenosis group were lower than the LV-sMBF ((1.94±0.63) ml·min-1·g-1) and MFR (2.00±0.58) of control group; all semi-quantitative parameters were higher than control group (all P<0.05). At the vascular level, with coronary artery stenosis ≥50% as the diagnosis criteria, the sMBF ((1.26±0.49) ml·min-1·g-1) and MFR (1.35±0.46) of stenosis group were lower than the sMBF ((1.95±0.70) ml·min-1·g-1) and MFR (2.05±0.65) of control group; SS and DS were higher than control group (all P<0.05). With coronary artery stenosis≥75% as the diagnosis criteria, the sMBF ((1.12±0.41) ml·min-1·g-1) and MFR (1.25±0.38) of stenosis group were lower than the sMBF ((1.84±0.70) ml·min-1·g-1) and MFR (1.93±0.66) of control group; all semi-quantitative parameters were higher than control group (all P<0.05). With coronary artery stenosis≥50% as the diagnosis criteria and CAG as the reference standard, the AUC and 95%CI of myocardial quantitative blood flow parameters indicated by ROC curve for diagnosis of CAD were 0.830 (0.783-0.877). The sensitivity (86.1% vs. 61.5%), specificity (82.6% vs. 73.8%), positive predictive value (77.8% vs. 62.5%), negative predictive value (89.3% vs. 73.0%) and accuracy (84.0% vs. 68.7%) were all higher than the semi-quantitative parameters (all P<0.05). With coronary artery stenosis≥75% as the diagnosis criteria, the AUC and 95%CI of myocardial quantitative blood flow parameters indicated by ROC curve for diagnosis of CAD were 0.832(0.785-0.879). The sensitivity (89.2% vs. 67.6%), negative predictive value (95.5% vs. 86.2%) and accuracy (80.6% vs. 68.0%) were all higher than semi-quantitative parameters (all P<0.05). Conclusion: Compared with traditional SPECT MPI derived semi-quantitative parameters, diagnostic efficacy for CAD is higher using CZT SPECT quantitative myocardial blood flow parameters, this strategy thus has additional diagnostic benefits and incremental value on the diagnosis of CAD.

Quantitative Blood Flow Measurements in the Common Carotid Artery: A Comparative Study of High-Frame-Rate Ultrasound Vector Flow Imaging, Pulsed Wave Doppler, and Phase Contrast Magnetic Resonance Imaging.

V Flow is commercially developed by high-frame-rate ultrasound vector flow imaging. Compared to conventional color Doppler, V Flow is angle-independent and is capable of measuring both the magnitude and the direction of blood flow velocities. This paper aims to investigate the differences between V Flow and pulsed wave Doppler (PW) relative to phase contrast magnetic resonance imaging (PC-MRI), for the quantitative measurements of blood flow in common carotid arteries (CCA) and, consequently, to evaluate the accuracy of the new technique, V Flow. Sixty-four CCAs were measured using V Flow, PW, and PC-MRI. The maximum velocities, time-averaged mean (TAMEAN) velocities, and volume flow were measured using different imaging technologies. The mean error with standard deviation (Std), the median of absolute errors, and the r-values between V Flow and PC-MRI results for the maximum velocity, the TAMEAN velocity, and the volume flow measurements are {9.40% ± 14.91%; 11.84%; 0.84}, {21.52% ± 14.46%; 19.28%; 0.86}, and {−2.80% ± 14.01%; 10.38%; 0.7}, respectively, and are {53.44% ± 29.68%; 49.79%; 0.74}, {27.83% ± 31.60%; 23.83; 0.71}, and {21.01% ± 29.64%; 25.48%; 0.34}, respectively, for those between PW and PC-MRI. The boxplot, linear regression and Bland–Altman plots were performed for each comparison, which illustrated that the results measured via V Flow rather than via PW agreed more closely with those measured via PC-MRI.