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Purpose: This study evaluated the effect of an increase in the time interval between hepatic intra-arterial injection of 99mTc-macroaggregated albumin (MAA) and hepatic artery perfusion scintigraphy (HAPS) on the lung shunt fraction (LSF) and perfused volume (PV) calculations in the treatment planning of selective internal radiation therapy (SIRT). Methods: The authors enrolled 51 HAPS sessions from 40 patients diagnosed with primary or metastatic liver malignancy. All patients underwent scan at the first and fourth hour after hepatic arterial injection of 99mTc-MAA. Based on single-photon emission computed tomography images, LSF values were measured from each patient's first and fourth hour images. PV1 and PV4 were also calculated based on three-dimensional images using 5% and 10% cutoff threshold values and compared with each other. Results: The authors found that the median of LSF4 was statistically significantly higher than LSF1 (3.05 vs. 4.14, p ≤ 0.01). There was no statistically significant difference between PV1 and PV4 on the 10% (p = 0.72) thresholds. Conclusions: LSF values can be overestimated in case of delayed HAPS, potentially leading to treatment cancellation due to incorrectly high results in patients who could benefit from SIRT. Threshold-based PV values do not significantly change over time; nevertheless, keeping the short interval time would be safer. [ABSTRACT FROM AUTHOR]

To determine the usefulness of multiparametric magnetic resonance (MR) quantitative imaging in characterizing the kidneys in systemic sclerosis (SSc) patients. Forty-six SSc patients (47.9 ± 12.8 years, 40 females) and 22 age- and sex- matched healthy volunteers (46.1 ± 13.8 years, 20 females) were recruited and underwent renal MR imaging by acquiring blood oxygen level dependent and saturated multi-delay renal arterial spin labeling (SAMURAI) sequences. The T2* value, T1 value, renal blood flow (RBF), arterial bolus arrival time (aBAT), and tissue bolus arrival time (tBAT) of renal cortex were measured and compared among diffuse cutaneous SSc (dcSSc) and limited cutaneous SSc (lcSSc) groups and healthy controls using One-way ANOVA and analyzed by logistic regression. Compared to healthy volunteers, SSc patients with normal estimated glomerular filtration rate (n = 40) had significantly lower T2* value (P = 0.026) in the left renal cortex, longer T1 value (right: P = 0.015; left: P = 0.023), lower RBF (right: P < 0.001; left: P < 0.001), and shorter tBAT (right: P < 0.001; left: P = 0.005) in both right and left renal cortex after adjusting for demographics. The dcSSc patients (n = 23) had significantly lower RBF in both right (226.7 ± 65.2 mL/100 g/min vs. 278.2 ± 73.5 mL/100 g/min, P = 0.022) and left (194.5 ± 71.5 mL/100 g/min vs. 252.7 ± 84.4 mL/100 g/min, P = 0.020) renal cortex compared to the lcSSc patients (n = 23) after adjusting for demographics, but the significance of the difference was attenuated after further adjusting for modified Rodnan skin score and digital ulcers. Multi-parametric MR quantitative imaging, particularly multi-delay ASL perfusion imaging, is a useful technique for characterizing the kidneys and classification of SSc patients. • Multiparametric MR quantitative imaging was utilized to characterize the impairment of renal microstructure and function in SSc patients. • Compared to the healthy volunteers, the SSc patients were more likely to have significantly lower T2*, longer T1, lower RBF, and shorter tBAT. • The dcSSc patients were found to have significantly lower RBF than the lcSSc patients. [ABSTRACT FROM AUTHOR]

Gated radionuclide angiography and myocardial perfusion imaging were developed in the United States and Europe in the 1970's and soon adopted in Canadian centers. Much of the early development of nuclear cardiology in Canada was in Toronto, Ontario and was quickly followed by new programs across the country. Clinical research in Canada contributed to the further development of nuclear cardiology and cardiac PET. The Canadian Nuclear Cardiology Society (CNCS) was formed in 1995 and became the Canadian Society of Cardiovascular Nuclear and CT Imaging (CNCT) in 2014. The CNCS had a major role in education and advocacy for cardiovascular nuclear medicine testing. The CNCS established the Dr Robert Burns Lecture and CNCT named the Canadian Society of Cardiovascular Nuclear and CT Imaging Annual Achievement Award for Dr Michael Freeman in memoriam of these two outstanding Canadian leaders in nuclear cardiology. The future of nuclear cardiology in Canada is exciting with the expanding use of SPECT imaging to include Tc-99m-pyrophosphate for diagnosis of transthyretin cardiac amyloidosis and the ongoing introduction of cardiac PET imaging. [ABSTRACT FROM AUTHOR]

State of the art of cardiac SPECT imaging continues to advance. Contemporary clinical applications of cardiac SPECT are reviewed and illustrated. Beyond traditional stress and rest myocardial perfusion imaging, the role of digital SPECT technology, ultra low dose imaging with efficient stress first / stress only if normal imaging, deep learning algorithms relative to coronary angiography and SPECT CT, sourceless emission attenuation correction, myocardial blood flow and blood flow reserve to assess ischemic jeopardy, culprit ischemic territories, and cardiac allograft vasculopathy, advanced methods of SPECT detection of amyloid cardiomyopathy, resting MPI to define pre-operative regional scar prior to operative ablation, parametric radionuclide ventriculography to quantify dyssynchrony and benefit of biventricular pacing, assessment of treatment response of RV and LV function in patients with pulmonary hypertension, dual isotope MIBG imaging to assess cardiac risk, and the value proposition of real world effectiveness of SPECT cardiac imaging are illustrated. [ABSTRACT FROM AUTHOR]

The addition of absolute myocardial blood flow (MBF) data improves the diagnostic and prognostic accuracy of relative perfusion imaging with nuclear medicine. Cardiac-specific gamma cameras allow measurement of MBF with SPECT. This paper reviews the evidence supporting the use of SPECT to measure myocardial blood flow (MBF). Studies have evaluated SPECT MBF in large animal models and compared it in humans with invasive angiographic measurements and against the clinical standard of PET MBF. The repeatability of SPECT MBF has been determined in both single-site and multi-center trials. SPECT MBF has excellent correlation with microspheres in an animal model, with the number of stenoses and fractional flow reserve, and with PET-derived MBF. The inter-user coefficient of variability is ∼20% while the COV of test-retest MBF is ∼30%. SPECT MBF improves the sensitivity and specificity of the detection of multi-vessel disease over relative perfusion imaging and provides incremental value in predicting adverse cardiac events. SPECT MBF is a promising technique for providing clinically valuable information in the assessment of coronary artery disease. [ABSTRACT FROM AUTHOR]

Positron emission tomography (PET) myocardial perfusion imaging in conjunction with tracer-kinetic modeling enables the concurrent assessment of myocardial perfusion and regional myocardial blood flow (MBF) of the left ventricle in absolute terms in milliliters per gram per minute (mL/g/min). The non-invasive quantification of MBF during pharmacologically induced hyperemia, at rest, and corresponding myocardial flow reserve (MFR) opens a new avenue for the identification and characterization of classical or endogen type of coronary microvascular dysfunction (CMD) as functional substrate for microvascular angina in patients with non-obstructive coronary artery disease (CAD) and/or no CAD at all. Further, PET-MBF quantification expands the scope of conventional myocardial perfusion imaging from the identification of advanced, and flow-limiting, epicardial CAD to early stages of atherosclerosis and/or CMD. Adding MBF assessment to myocardial perfusion may also reliably unravel diffuse ischemia owing to significant left main stenosis and/or multivessel CAD, commonly confirmed by peak stress transient ischemic cavity dilation of the left ventricle during maximal vasomotor stress compared to rest on gated PET images. Owing to high spatial and contrast resolution in conjunction with photon-attenuation free myocardial perfusion PET images, PET is preferentially used for CAD detection in advanced obesity and women with pronounced breast habitus. With increasing clinical use of cardiac PET perfusion and MBF assessment, individualized, and image-guided cardiovascular treatment decisions in CAD patients is likely to ensue, while its translation into improved cardiovascular outcome remains to be investigated. [ABSTRACT FROM AUTHOR]

Arterial spin labeling (ASL) has been widely used to evaluate arterial blood and perfusion dynamics, particularly in the brain, but its application to the spinal cord has been limited. The purpose of this study was to optimize vessel‐selective pseudocontinuous arterial spin labeling (pCASL) for angiographic and perfusion imaging of the rat cervical spinal cord. A pCASL preparation module was combined with a train of gradient echoes for dynamic angiography. The effects of the echo train flip angle, label duration, and a Cartesian or radial readout were compared to examine their effects on visualizing the segmental arteries and anterior spinal artery (ASA) that supply the spinal cord. Lastly, vessel‐selective encoding with either vessel‐encoded pCASL (VE‐pCASL) or super‐selective pCASL (SS‐pCASL) were compared. Vascular territory maps were obtained with VE‐pCASL perfusion imaging of the spinal cord, and the interanimal variability was evaluated. The results demonstrated that longer label durations (200 ms) resulted in greater signal‐to‐noise ratio in the vertebral arteries, improved the conspicuity of the ASA, and produced better quality maps of blood arrival times. Cartesian and radial readouts demonstrated similar image quality. Both VE‐pCASL and SS‐pCASL adequately labeled the right or left vertebral arteries, which revealed the interanimal variability in the segmental artery with variations in their location, number, and laterality. VE‐pCASL also demonstrated unique interanimal variations in spinal cord perfusion with a right‐sided dominance across the six animals. Vessel‐selective pCASL successfully achieved visualization of the arterial inflow dynamics and corresponding perfusion territories of the spinal cord. These methodological developments provide unique insights into the interanimal variations in the arterial anatomy and dynamics of spinal cord perfusion. [ABSTRACT FROM AUTHOR]

This paper presents an optical biosensor system including a TFT (thin‐film transistor) sensor array and silicon IC to capture vein images, record PPG (photoplethysmography) signals and generate blood perfusion images. The sensing area is 1200 mm2 including 21168 pixels and SNR (signal‐to‐noise ratio) is 56 dB when FPS (frames per second) is 270. [ABSTRACT FROM AUTHOR]

Purpose: Background suppression (BS) is recommended in arterial spin labeling (ASL) for improved SNR but is difficult to optimize in existing velocity-selective ASL (VSASL) methods. Dual-module VSASL (dm-VSASL) enables delay-insensitive, robust, and SNR-efficient perfusion imaging, while allowing efficient BS, but its optimization has yet to be thoroughly investigated. Methods: The inversion effects of the velocity-selective labeling pulses, such as velocity-selective inversion (VSI), can be used for BS, andwere modeled for optimizing BS in dm-VSASL. In vivo experiments using dual-module VSI (dm-VSI) were performed to compare two BS strategies: a conventional one with additional BS pulses and a new one without any BS pulse. Their BS performance, temporal noise, and temporal SNR were examined and compared, with pulsed and pseudo-continuous ASL (PASL and PCASL) as the reference. Results: The in vivo experiments validated the BS modeling. Strong positive linear correlations (r >0.82, p<0.0001) between the temporal noise and the tissue signal were found in PASL/PCASL and dm-VSI. Optimal BS can be achieved with and without additional BS pulses in dm-VSI; the latter improved the ASL signals by 8.5% in gray matter (p=0.006) and 12.2% in white matter (p=0.014) and tended to provide better temporal SNR. The dm-VSI measured significantly higher ASL signal (p<0.016) and temporal SNR (p<0.018) than PASL and PCASL. Complex reconstruction was found necessary with aggressive BS. Conclusion: Guided by modeling, optimal BS can be achieved without any BS pulse in dm-VSASL, further improving the ASL signal and the SNRperformance. [ABSTRACT FROM AUTHOR]

Background: Head and neck tissue defects after ablative surgery often require complex and composite reconstructions. The superficial circumflex iliac artery perforator (SCIP) flap is an extremely versatile perforator‐based flap with minimal donor site morbidity, which may represent the optimal procedure in this setting. Over the last 5 years, we collected a large base of experience, including both simple and chimeric SCIP‐based reconstruction, making this flap our first choice for head and neck reconstructions. Patients and Methods: Seventy‐three patients undergoing ablative head and neck surgery for oncologic pathologies were treated by means of a SCIP flap reconstruction. Patients' mean age was 67 years old (range 37–89), 51 were males and 22 were females. Fifty‐eight flaps were simple and 15 were chimeric reconstruction patterns. Indocyanine green perfusion imaging was performed in all cases. Results: All the patients were successfully treated with no flap losses were encountered. Twelve patients encountered postoperative complications: in four cases revision surgery was required for venous congestion, while the remaining cases were managed conservatively (four wound dehiscence and three infections). No patients showed donor site complications. The mean follow‐up period was 11 months (range 3–24). Conclusions: Our case series demonstrates the reliability and versatility of the SCIP flap for different kinds of head and neck reconstructions. The chimeric options combined with bone, double skin paddle, and muscle offer a broad variety of functional reconstructive solutions for complex head and neck surgeries. Intraoperative indocyanine green perfusion examination provides a valuable tool to assess and ascertain proper vascularization and post‐anastomosis vessel patency in complex microvascular flap‐based reconstructions. [ABSTRACT FROM AUTHOR]

Background Perfusion imaging (PI) serves as a valuable tool for triaging patients with acute ischemic stroke for endovascular treatment (EVT). This study aims to investigate trends in PI use and its impacts on EVT rates and clinical outcomes, particularly focusing on variations across different time windows. Methods Data from a prospective, nationwide, acute stroke registry in South Korea were analyzed retrospectively. PI was regarded as treatment‐decision imaging when conducted either (1) prior to EVT, or (2) within 3 hours from hospital arrival in patients not receiving EVT. The study spanned 3 epochs: 2011–2014, 2015–2017, and 2018–2021. Based on the time from onset to arrival, patients were categorized into 2 time windows: early (0–6 hours) and late (6–24 hours). We evaluated EVT rates and clinical outcomes in patients with anterior large vessel occlusion. Results From 2011 to 2021 among 49 449 patients with acute ischemic stroke presenting within 24 hours of onset, PI use rates declined from 36.9% to 30.1%. In the early window, rates dropped from 48.4% to 32.4%, whereas in the late window, they increased from 23.5% to 27.8%. Factors such as older age, atrial fibrillation, anterior large vessel occlusion, and severe stroke were associated with higher rates in the late window. Conversely, younger age and male sex were associated with higher rates in the early window. For patients with anterior large vessel occlusion, PI use increased the likelihood of receiving EVT in the late window and minimized the risk of symptomatic intracranial hemorrhage in the early window. However, 3‐month functional outcomes and mortality were. unaffected. Conclusion The study revealed distinct trends in PI use across early and late time windows, indicating varying roles of PI in these time frames. However, the definitive value and necessity of PI in guiding EVT decision‐making remain unclear, underscoring the need for further research

The editorial in the European Radiology journal discusses the importance of considering venous outflow (VO) in making decisions for endovascular thrombectomy (EVT) in stroke patients within the late time window (6-24 hours). The study highlights the significance of venous outflow in predicting favorable clinical outcomes, especially in the absence of reliable arterial collateral circulation. The findings suggest that a higher optimal threshold of venous opacification score (COVES) is necessary for achieving functional independence in late window stroke patients, emphasizing the need for personalized prediction systems based on pre-operative CT angiography. Future studies with larger, more homogeneous samples are recommended to validate these findings and establish effective stroke management strategies. [Extracted from the article]

BackgroundIn contrast to conventional CT perfusion (CTP) imaging, flat panel detector CT perfusion (FD-CTP) imaging can be acquired directly in the angiosuite.ObjectiveTo evaluate time-resolved whole brain FD-CTP imaging and assess clinically important qualitative and quantitative perfusion parameters in correlation with previously acquired conventional CTP using the new RAPID for ANGIO software.MethodsWe included patients with internal carotid artery occlusions and M1 or M2 occlusions from six centers. All patients underwent mechanical thrombectomy (MT) with preinterventional conventional CTP and FD-CTP imaging. Quantitative performance was determined by comparing volumes of infarct core, penumbral tissue, and mismatch. Eligibility for MT according to the perfusion imaging criteria of DEFUSE 3 was determined for each case from both conventional CTP and FD-CTP imaging.ResultsA total of 20 patients were included in the final analysis. Conventional relative cerebral blood flow (rCBF) 6 s versus FD-CTP Tmax >6 s and CTP mismatch versus FD-CTP mismatch showed more variability (R2=0.57, and R2=0.33, respectively). Based on FD-CTP, 16/20 (80%) patients met the inclusion criteria for MT according to the DEFUSE 3 perfusion criteria, in contrast to 18/20 (90%) patients based on conventional CTP. The vessel occlusion could be correctly extrapolated from the hypoperfusion in 18/20 cases (90%).ConclusionsIn our multicenter study, time-resolved whole brain FD-CTP was technically feasible, and qualitative and quantitative perfusion results correlated with those obtained with conventional CTP.

Background: The intravoxel Incoherent Motion (IVIM) model extracts perfusion map and diffusion coefficient map using diffusion-weighted imaging. The main limitation of this model is inaccuracy in the presence of noise.Objective: This study aims to improve the accuracy of IVIM output parameters.Material and Methods: In this simulated and analytical study, the Kalman filter is applied to reject artifact and measurement noise. The proposed method purifies the diffusion coefficient from blood motion and noise, and then an artificial neural network is deployed in estimating perfusion parameters.Results: Based on the T-test results, however, the estimated parameters of the conventional method were significantly different from actual values, those of the proposed method were not substantially different from actual. The accuracy of f and D* also was improved by using Artificial Neural Network (ANN) and their bias was minimized to 4% and 12%, respectively. Conclusion: The proposed method outperforms the conventional method and is a promising technique, leading to reproducible and valid maps of D, f, and D*.

PURPOSE: To improve image quality and resolution of dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI) by developing acquisition and reconstruction methods exploiting the temporal regularity property of DSC-PWI signal. THEORY AND METHODS: A novel regularized reconstruction is proposed that recovers DSC-PWI series from interleaved segmented spiral k-space acquisition using higher order temporal smoothness (HOTS) properties of the DSC-PWI signal. The HOTS regularization is designed to tackle representational insufficiency of the standard first-order temporal regularizations for supporting higher accelerations. The higher accelerations allow for k-space coverage with shorter spiral interleaves resulting in improved acquisition point spread function, and acquisition of images at multiple TEs for more accurate DSC-PWI analysis. RESULTS: The methods were evaluated in simulated and in-vivo studies. HOTS regularization provided increasingly more accurate models for DSC-PWI than the standard first-order methods with either quadratic or robust norms at the expense of increased noise. HOTS DSC-PWI optimized for noise and accuracy demonstrated significant advantages over both spiral DSC-PWI without temporal regularization and traditional echo-planar DSC-PWI, improving resolution and mitigating image artifacts associated with long readout, including blurring and geometric distortions. In context of multi-echo DSC-PWI, the novel methods allowed ∼4.3× decrease of voxel volume, providing 2× number of TEs compared to the previously published results. CONCLUSIONS: Proposed HOTS reconstruction combined with dynamic spiral sampling represents a valid mechanism for improving image quality and resolution of DSC-PWI significantly beyond those available with established fast imaging techniques.

Patients with Parkinson's disease (PD) experience significantly reduced quality of life when PD is complicated with Pisa syndrome (PS). PS is a postural abnormality associated with a lateral bending of the trunk, causing the patient to lean to one side. Microsaccades during fixation are transmitted to the visual cortex, and this gaze movement may be impaired in PD. We aimed to detect presymptomatic signs of PS. We enrolled 50 patients with PD without dementia and investigated the visual systems in patients with concurrent PD and PS based on a Romberg ratio of<1.0. Gaze analysis, pupil diameter, stabilization tests, neuropsychological tests, and cerebral perfusion scintigraphy were reviewed and statistically analyzed. Two years later, we divided the patients into three groups as follows: PISA++ (patients who had PS at enrollment), PISA‐+ (patients without PS that developed PS during the 2‐year period), and PISA‐‐ (patients without PS that did not develop PS during the 2‐year period). The PISA‐+ group exhibited a significantly higher daily levodopa dose and longer fixations, as well as lower position discrimination, Wechsler Adult Intelligence Scale‐Third Edition blocking, and blood flow in the left supramarginal and orbital gyri than that in the PISA‐‐ group. The PISA++ group showed a significantly longer fixation time and lower Mini‐Mental State Examination score, Romberg ratio of area, amplitude, velocity of microsaccades, and blood flow in the left precuneus and cuneus than that in the PISA‐+ group. Before the onset of PS, hypoperfusion occurred in the correlative visual cortex and the position discrimination test. Patients with PS have reduced saccades and slow microsaccades. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the predictive value of multi-parameters derived from advanced MR imaging for Ki-67 labeling index (LI) in glioma patients. Materials and Methods: One hundred and nine patients with histologically confirmed gliomas were evaluated retrospectively. These patients underwent advanced MR imaging, including dynamic susceptibility-weighted contrast enhanced MR imaging (DSC), MR spectroscopy imaging (MRS), diffusionweighted imaging (DWI) and diffusion-tensor imaging (DTI), before treatment. Twenty-one parameters were extracted, including the maximum, minimum and mean values of relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), relative apparent diffusion coefficient (rADC), relative fractional anisotropy (rFA) and relative mean diffusivity (rMD) respectively, and ration of choline (Cho)/creatine (Cr), Cho/N-acetylaspartate (NAA) and NAA/Cr. Stepwise multivariate regression was performed to build multivariate models to predict Ki-67 LI. Pearson correlation analysis was used to investigate the correlation between imaging parameters and the grade of glioma. One-way analysis of variance (ANOVA) was used to explore the differences of the imaging parameters among the gliomas of grade II, III, and IV. Results: The multivariate regression showed that the model of five parameters, including rCBVmax (RC=0.282), rCBFmax (RC=0.151), rADCmin (RC= -0.14), rFAmax (RC=0.325) and Cho/Cr ratio (RC=0.157) predicted the Ki-67 LI with a root mean square (RMS) error of 0. 0679 (R2 = 0.8025). The regression check of this model showed that there were no multicollinearity problem (variance inflation factor: rCBVmax, 3.22; rCBFmax, 3.14; rADCmin, 1.96; rFAmax, 2.51; Cho/Cr ratio, 1.64), and the functional form of this model was appropriate (F test: p=0.682). The results of Pearson correlation analysis showed that the rCBVmax, rCBFmax, rFAmax, the ratio of Cho/Cr and Cho/NAA were positively correlated with Ki-67 LI and the grade of glioma, while the rADCmin and rMDmin were negatively correlated with Ki-67 LI and the grade of glioma. Conclusion: Combining multiple parameters derived from DSC, DTI, DWI and MRS can precisely predict the Ki-67 LI in glioma patients. [ABSTRACT FROM AUTHOR]

Background: The restoration of cerebrovascular regulation and improvement of cerebral blood flow in ischaemic regions are crucial for improving the clinical prognosis after stroke. An-Gong-Niu-Huang-Wan (AGNHW) is a famous traditional compound Chinese medicine that has been used for over 220 years to treat acute ischaemic stroke; however, its role in the regulation of cerebral blood flow is still unclear. The aim of the present study was to investigate the regulatory effect of AGNHW on cerebral blood flow and microcirculation after ischaemic stroke and to elucidate the underlying mechanisms involved. Methods: Male C57BL/6 mice were subjected to distal middle cerebral artery occlusion (dMCAO) and randomly assigned to the sham, MCAO, or AGNHW groups. AGNHW was administered intragastrically 1 h after dMCAO. The rotarod test was utilized to evaluate behavioural function; TTC was used to determine the infarct volume; and ischaemic injury was assessed by detecting brain levels of SOD, MDA and NO. Then, cortical perfusion and acetazolamide-induced cerebrovascular reactivity were assessed using laser speckle contrast imaging, and the velocity and flux of red blood cells in cortical capillaries were detected using two-photon laser scanning microscopy. In addition, we employed RNA-Seq to identify variations in gene expression profiles and assessed endothelium-dependent changes in microcirculatory dysfunction by measuring vasoactive mediator levels. Results: AGNHW significantly increased cerebral blood flow, reduced the infarct volume, and promoted functional recovery after cerebral ischaemia. AGNHW increased the velocity and flux of red blood cells in capillaries and improved cerebrovascular reactivity in the ischaemic cortex. Furthermore, AGNHW regulated endothelium-dependent microcirculation, as evidenced by decreases in the expression of endothelins (Edn1, Edn3 and Ednrb) and the ratios of brain and serum TXB2/6-keto-PGF1α and ET-1/CGRP. Conclusions: AGNHW improved cerebral hypoperfusion, regulated cerebrovascular reactivity and attenuated microcirculatory dysfunction within the ischaemic cortex after stroke. This outstanding effect was achieved by modulating the expression of genes related to vascular endothelial cell function and regulating endothelium-dependent vasoactive mediators. [ABSTRACT FROM AUTHOR]

Compared to classical techniques of morphological analysis, micro-CT (μ-CT) has become an effective approach allowing rapid screening of morphological changes. In the present work, we aimed to provide an optimized micro-CT dense agent perfusion protocol and μ-CT guidelines for different stages of chick embryo cardiogenesis. Our study was conducted over a period of 10 embryonic days (Hamburger-Hamilton HH36) in chick embryo hearts. During the perfusion of the micro-CT dense agent at different developmental stages (HH19, HH24, HH27, HH29, HH31, HH34, HH35, and HH36), we demonstrated that durations and volumes of the injected contrast agent gradually increased with the heart developmental stages contrary to the flow rate that was unchanged during the whole experiment. Analysis of the CT imaging confirmed the efficiency of the optimized parameters of the heart perfusion. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) promotes angiogenesis via various mechanisms; however, the effective transmission of NO in ischemic diseases is unclear. Herein, we tested whether NO-releasing nanofibers modulate therapeutic angiogenesis in an animal hindlimb ischemia model. Male wild-type C57BL/6 mice with surgically-induced hindlimb ischemia were treated with NO-releasing 3-methylaminopropyltrimethoxysilane (MAP3)–derived or control (i.e., non-NO-releasing) nanofibers, by applying them to the wound for 20 min, three times every two days. The amount of NO from the nanofiber into tissues was assessed by NO fluorometric assay. The activity of cGMP-dependent protein kinase (PKG) was determined by western blot analysis. Perfusion ratios were measured 2, 4, and 14 days after inducing ischemia using laser doppler imaging. On day 4, Immunohistochemistry (IHC) with F4/80 and gelatin zymography were performed. IHC with CD31 was performed on day 14. To determine the angiogenic potential of NO-releasing nanofibers, aorta-ring explants were treated with MAP3 or control fiber for 20 min, and the sprout lengths were examined after 6 days. As per either LDPI (Laser doppler perfusion image) ratio or CD31 capillary density measurement, angiogenesis in the ischemic hindlimb was improved in the MAP3 nanofiber group; further, the total nitrate/nitrite concentration in the adduct muscle increased. The number of macrophage infiltrations and matrix metalloproteinase-9 (MMP-9) activity decreased. Vasodilator-stimulated phosphoprotein (VASP), one of the major substrates for PKG, increased phosphorylation in the MAP3 group. MAP3 nanofiber or NO donor SNAP (s-nitroso-n-acetyl penicillamine)-treated aortic explants showed enhanced sprouting in an ex vivo aortic ring assay, which was partially abrogated by KT5823, a potent inhibitor of PKG. These findings suggest that the novel NO-releasing nanofiber, MAP3 activates PKG and promotes therapeutic angiogenesis in response to hindlimb ischemia. [ABSTRACT FROM AUTHOR]

Objective: Evaluation of the predictive value of one-stop energy spectrum and perfusion CT parameters for microvessel density (MVD) in colorectal cancer cancer foci. Methods: Clinical and CT data of 82 patients with colorectal cancer confirmed by preoperative colonoscopy or surgical pathology in our hospital from September 2019 to November 2022 were collected and analyzed retrospectively. Energy spectrum CT images were measured using the Protocols general module of the GSI Viewer software of the GE AW 4.7 post-processing workstation to measure the CT values of the arterial and venous phase lesions and the neighboring normal intestinal wall in a single energy range of 40 kev∼140 kev, and the slopes of the energy spectrum curves (λ) were calculated between 40 kev-90 kev; Iodine concentration (IC), Water concentration (WC), Effective-Z (Eff-Z) and Normalized iodine concentration (NIC) were measured by placing a region of interest (ROI) on the iodine concentration map and water concentration map at the lesion and adjacent to the normal intestinal wall.Perfusion CT images were scanned continuously and dynamically using GSI Perfusion software and analyzed by applying CT Perfusion 4.0 software.Blood volume (BV), blood flow (BF), surface permeability (PS), time to peak (TTP), and mean transit time (MTT) were measured respectively in the lesion and adjacent normal colorectal wall. Based on the pathological findings, the tumors were divided into a low MVD group (MVD < 35/field of view, n = 52 cases) and a high MVD group (MVD ≥ 35/field of view, n = 30 cases) using a median of 35/field of view as the MVD grouping criterion. The collected data were statistically analyzed, the subjects' operating characteristic curve (ROC) was plotted, and the area under curve (AUC), sensitivity, specificity, and Yoden index were calculated for the predicted efficacy of each parameter of the energy spectrum and perfusion CT and the combined parameters. Results: The CT values, IC, NIC, λ, Eff-Z of 40kev∼140kev single energy in the arterial and venous phase of colorectal cancer in the high MVD group were higher than those in the low MVD group, and the differences were all statistically significant (p < 0.05). The AUC of each single-energy CT value in the arterial phase from 40 kev to 120 kev for determining the high or low MVD of colorectal cancer was greater than 0.8, indicating that arterial stage has a good predictive value for high or low MVD in colorectal cancer; AUC for arterial IC, NIC and IC + NIC were all greater than 0.9, indicating that in arterial colorectal cancer, both single and combined parameters of spectral CT are highly effective in predicting the level of MVD. The AUC of 40 kev to 90 kev single-energy CT values in the intravenous phase was greater than 0.9, and its diagnostic efficacy was more representative; The AUC of IC and NIC in venous stage were greater than 0.8, which indicating that the IC and NIC energy spectrum parameters in venous stage colorectal cancer have a very good predictive value for the difference between high and low MVDs, with the greatest diagnostic efficacy in IC.The values of BV and BF in the high MVD group were higher than those in the low MVD group, and the differences were statistically significant (P < 0.05), and the AUC of BF, BV, and BV + BF were 0.991, 0.733, and 0.997, respectively, with the highest diagnostic efficacy for determining the level of MVD in colorectal cancer by BV + BF. Conclusion: One-stop CT energy spectrum and perfusion imaging technology can accurately reflect the MVD in living tumor tissues, which in turn reflects the tumor angiogenesis, and to a certain extent helps to determine the malignancy, invasion and metastasis of living colorectal cancer tumor tissues based on CT energy spectrum and perfusion parameters. [ABSTRACT FROM AUTHOR]

Simple Summary: Our study explores the capability of dynamic contrast-enhanced MRI (DCE-MRI) as an early predictor of disease progression in glioblastoma patients, compared to conventional MRI. We analyzed two cohorts comprising 26 patients with newly diagnosed primary glioblastoma. Patients were then categorized based on disease stage (progression or stability) and underwent three DCE-MRI scans prior to progression or consecutively for stable disease. Parameters such as Ktrans and plasma volume (Vp) were measured within the volume of interest (VOIs). Our findings revealed a gradual increase in Vp max values preceding disease progression in patients who underwent routine MRI scans. Utilizing quantitative DCE-MRI may offer an opportunity to detect disease progression earlier than conventional methods, potentially improving patient management by enabling proactive measures against progression. Background and Purpose: Distinguishing treatment-induced imaging changes from progressive disease has important implications for avoiding inappropriate discontinuation of a treatment. Our goal in this study is to evaluate the utility of dynamic contrast-enhanced (DCE) perfusion MRI as a biomarker for the early detection of progression. We hypothesize that DCE-MRI may have the potential as an early predictor for the progression of disease in GBM patients when compared to the current standard of conventional MRI. Methods: We identified 26 patients from 2011 to 2023 with newly diagnosed primary glioblastoma by histopathology and gross or subtotal resection of the tumor. Then, we classified them into two groups: patients with progression of disease (POD) confirmed by pathology or change in chemotherapy and patients with stable disease without evidence of progression or need for therapy change. Finally, at least three DCE-MRI scans were performed prior to POD for the progression cohort, and three consecutive DCE-MRI scans were performed for those with stable disease. The volume of interest (VOI) was delineated by a neuroradiologist to measure the maximum values for Ktrans and plasma volume (Vp). A Friedman test was conducted to evaluate the statistical significance of the parameter changes between scans. Results: The mean interval between subsequent scans was 57.94 days, with POD-1 representing the first scan prior to POD and POD-3 representing the third scan. The normalized maximum Vp values for POD-3, POD-2, and POD-1 are 1.40, 1.86, and 3.24, respectively (FS = 18.00, p = 0.0001). It demonstrates that Vp max values are progressively increasing in the three scans prior to POD when measured by routine MRI scans. The normalized maximum Ktrans values for POD-1, POD-2, and POD-3 are 0.51, 0.09, and 0.51, respectively (FS = 1.13, p < 0.57). Conclusions: Our analysis of the longitudinal scans leading up to POD significantly correlated with increasing plasma volume (Vp). A longitudinal study for tumor perfusion change demonstrated that DCE perfusion could be utilized as an early predictor of tumor progression. [ABSTRACT FROM AUTHOR]

Background and Purpose: Frontotemporal dementia (FTD) is the second most common cause of presenile dementia. The clinical distinction between FTD, Alzheimer's disease (AD), and other dementias is a clinical challenge. Brain perfusion SPECT may contribute to the diagnosis of FTD, but its value is unclear. Methods: We performed a systematic review to investigate the diagnostic accuracy of the brain SPECT in (1) distinguishing FTD from AD and other dementias and (2) differentiating FTD variants. Results: Overall, 391 studies were retrieved on the initial search and 35 studies composed the final selection, comprising a total number of 3142 participants of which 1029 had FTD. The sensitivity and the specificity for the differential diagnosis of FTD versus AD ranged from 56% to 88% and from 51% to 93%, respectively. SPECT is not superior to the clinical method of diagnosis, but the combination of SPECT with clinical data seems to improve the diagnostic accuracy. Conclusion: Brain perfusion SPECT has a limited value in the diagnostic framework of FTD. SPECT can be performed when FDG‐PET is not available. SPECT is recommended only for selected cases when the diagnosis is challenging using conventional methods. [ABSTRACT FROM AUTHOR]

Background: The legalization of cannabis use and false claims about the plant Cannabis sativa to be considered a pharmaceutical product have been found to increase consumption, lower risk perception, and lead to more health problems, without reducing criminal activity. Brain function, typically assessed by neuropsychological tests, shows abnormalities with acute marijuana use, but inconsistent results have been published after abstinence, with a maximum follow-up of 28 days. Our previous research, using neuropsychological tests and brain perfusion single photon emission computed tomography (neuroSPECT), demonstrated consistent abnormalities in brain function among schoolchildren who consume marijuana compared to their non-consuming peers. The aim of this study is to investigate whether brain function changes in 20 adult marijuana users after 6 months of abstinence. Methodology: Comparison of neuropsychological tests (Rey Complex Figure; Porteus Maze; Four subtests of WAIS-IV Intellectual Tests; STROOP; D2) and perfusion neuroSPECT (functional images), obtained in relation to recent consumption and after 6 months of serial drug-screening test confirmed abstinence. Results: In a one-year period (2020-2021) only five compliant participants were recruited. The COVID-19 pandemic was a limiting factor. Preliminary results of neuropsychological tests, functional brain perfusion images and limited statistical analysis are presented. The results of the neuropsychological tests of the three subjects who completed the abstinence period so far show some improvement in working memory and attention after abstinence. NeuroSPECT shows disorganized hypoperfusion of variable severity in relation to recent consumption, involving areas associated with cognitive function such as the posterior cingulate and temporal lobes, in our five initially enrolled patients, when compared to a normal database. Of these, only two participants have already been re-evaluated with neuroSPECT after 6 months of abstinence, one of whom showed some improvement on the post-abstinence images. Conclusion: We analyze the methodological challenges of this research, including the pandemic, to incorporate the appropriate corrections in the next phase of our investigation. Our final findings may provide clinicians and users with information about the long-term effects of marijuana use on brain function. [ABSTRACT FROM AUTHOR]

The article discusses the timeless study evaluating the use of tenecteplase 4.5 to 24 hours post-stroke, concluding it doesn't improve outcomes compared to placebo, despite advancements in imaging for patient selection.

• Our multimodal quantitative method unveils directional dynamics of epileptic network during interictal to ictal transition. • Epileptogenic zone exhibits maximum outflow during preictal, and at seizure onset. • Regions that are hypoperfused during seizures exhibit maximum outflow during ictal evolution and can serve as a control network. Ictal Single Photon Emission Computed Tomography (SPECT) and stereo-electroencephalography (SEEG) are diagnostic techniques used for the management of patients with drug-resistant focal epilepsies. While hyperperfusion patterns in ictal SPECT studies reveal seizure onset and propagation pathways, the role of ictal hypoperfusion remains poorly understood. The goal of this study was to systematically characterize the spatio-temporal information flow dynamics between differently perfused brain regions using stereo-EEG recordings. We identified seizure-free patients after resective epilepsy surgery who had prior ictal SPECT and SEEG investigations. We estimated directional connectivity between the epileptogenic-zone (EZ), non-resected areas of hyperperfusion, hypoperfusion, and baseline perfusion during the interictal, preictal, ictal, and postictal periods. Compared to the background, we noted significant information flow (1) during the preictal period from the EZ to the baseline and hyperperfused regions, (2) during the ictal onset from the EZ to all three regions, and (3) during the period of seizure evolution from the area of hypoperfusion to all three regions. Hypoperfused brain regions were found to indirectly interact with the EZ during the ictal period. Our unique study, combining intracranial electrophysiology and perfusion imaging, presents compelling evidence of dynamic changes in directional connectivity between brain regions during the transition from interictal to ictal states. [ABSTRACT FROM AUTHOR]

To evaluate whole-node histogram parameters of blood flow (BF) maps derived from three-dimensional pseudo-continuous arterial spin-labelled (3D pCASL) imaging in discriminating metastatic from benign upper cervical lymph nodes (UCLNs) for nasopharyngeal carcinoma (NPC) patients. Eighty NPC patients with a total of 170 histologically confirmed UCLNs (67 benign and 103 metastatic) were included retrospectively. Pre-treatment 3D pCASL imaging was performed and whole-node histogram analysis was then applied. Histogram parameters and morphological features, such as minimum axis diameter (M in AD), maximum axis diameter (M ax AD), and location of UCLNs, were assessed and compared between benign and metastatic lesions. Predictors were identified and further applied to establish a combined model by multivariate logistic regression in predicting the probability of metastatic UCLNs. Receiver operating characteristic (ROC) curves were used to analyse the diagnostic performance. Metastatic UCLNs had larger M in AD and M in AD/M ax AD ratio, greater energy and entropy values, and higher incidence of level II (upper jugular group), but lower BF 10th value than benign nodes (all p <0.05). M in AD, BF 10th , energy, and entropy were validated as independent predictors in diagnosing metastatic UCLNs. The combined model yielded an area under the curve (AUC) of 0.932, accuracy of 84.42 %, sensitivity of 80.6 %, and specificity of 90.29 %. Whole-node histogram analysis on BF maps is a feasible tool to differentiate metastatic from benign UCLNs in NPC patients, and the combined model can further improve the diagnostic efficacy. • Whole-node histogram parameters could act as a noninvasive effective biomarker. • A nomogram combining histogram parameters and M in AD of UCLNs was constructed. • The nomogram could serve as a novel diagnostic tool for the status of UCLNs. [ABSTRACT FROM AUTHOR]

To explore the effect of ultrasound-stimulated microbubble cavitation (USMC) on enhancing antiangiogenic therapy in clear cell renal cell carcinoma. We explored the effects of USMC with different mechanical indices (MIs) on tumor perfusion, 36 786-O tumor-bearing nude mice were randomly assigned into four groups: (i) control group, (ii) USMC 0.25 group (MI = 0.25), (iii) USMC 1.4 group (MI = 1.4) (iv) US 1.4 group (MI = 1.4). Tumor perfusion was assessed by contrast-enhanced ultrasound (CEUS) before the USMC treatment and 30 min, 4h and 6h after the USMC treatment, respectively. Then we evaluated vascular normalization(VN) induced by low-MI (0.25) USMC treatment, 12 tumor-bearing nude mice were randomly divided into two groups: (i) control group (ii) USMC 0.25 group. USMC treatment was performed, and tumor microvascular imaging and blood perfusion were analyzed by MicroFlow imaging (MFI) and CEUS 30 min after each treatment. In combination therapy, a total of 144 tumor-bearing nude mice were randomly assigned to six groups (n = 24): (i) control group, (ii) USMC 1.4 group, (iii) USMC 0.25 group, (iv) bevacizumab(BEV) group, (v) USMC 1.4 +BEV group, (vi) USMC 0.25 +BEV group. BEV was injected on the 6th, 10th, 14th, and 18th d after the tumors were inoculated, while USMC treatment was performed 24 h before and after every BEV administration. We examined the effects of the combination therapy through a series of experiments. Tumor blood perfusion enhanced by USMC with low MI (0.25)could last for more than 6h, inducing tumor VN and promoting drug delivery. Compared with other groups, USMC 0.25 +BEV combination therapy had the strongest inhibition on tumor growth, led to the longest survival time of the mice. The optimized USMC is a promising therapeutic approach that can be combined with antiangiogenic therapy to combat tumor progression. [ABSTRACT FROM AUTHOR]

Purpose: Ktrans$$ {K}^{\mathrm{trans}} $$ has often been proposed as a quantitative imaging biomarker for diagnosis, prognosis, and treatment response assessment for various tumors. None of the many software tools for Ktrans$$ {K}^{\mathrm{trans}} $$ quantification are standardized. The ISMRM Open Science Initiative for Perfusion Imaging–Dynamic Contrast‐Enhanced (OSIPI‐DCE) challenge was designed to benchmark methods to better help the efforts to standardize Ktrans$$ {K}^{\mathrm{trans}} $$ measurement. Methods: A framework was created to evaluate Ktrans$$ {K}^{\mathrm{trans}} $$ values produced by DCE‐MRI analysis pipelines to enable benchmarking. The perfusion MRI community was invited to apply their pipelines for Ktrans$$ {K}^{\mathrm{trans}} $$ quantification in glioblastoma from clinical and synthetic patients. Submissions were required to include the entrants' Ktrans$$ {K}^{\mathrm{trans}} $$ values, the applied software, and a standard operating procedure. These were evaluated using the proposed OSIPIgold$$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score defined with accuracy, repeatability, and reproducibility components. Results: Across the 10 received submissions, the OSIPIgold$$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score ranged from 28% to 78% with a 59% median. The accuracy, repeatability, and reproducibility scores ranged from 0.54 to 0.92, 0.64 to 0.86, and 0.65 to 1.00, respectively (0–1 = lowest–highest). Manual arterial input function selection markedly affected the reproducibility and showed greater variability in Ktrans$$ {K}^{\mathrm{trans}} $$ analysis than automated methods. Furthermore, provision of a detailed standard operating procedure was critical for higher reproducibility. Conclusions: This study reports results from the OSIPI‐DCE challenge and highlights the high inter‐software variability within Ktrans$$ {K}^{\mathrm{trans}} $$ estimation, providing a framework for ongoing benchmarking against the scores presented. Through this challenge, the participating teams were ranked based on the performance of their software tools in the particular setting of this challenge. In a real‐world clinical setting, many of these tools may perform differently with different benchmarking methodology. [ABSTRACT FROM AUTHOR]

Purpose: To create an inventory of image processing pipelines of arterial spin labeling (ASL) and list their main features, and to evaluate the capability, flexibility, and ease of use of publicly available pipelines to guide novice ASL users in selecting their optimal pipeline. Methods: Developers self‐assessed their pipelines using a questionnaire developed by the Task Force 1.1 of the ISMRM Open Science Initiative for Perfusion Imaging. Additionally, each publicly available pipeline was evaluated by two independent testers with basic ASL experience using a scoring system created for this purpose. Results: The developers of 21 pipelines filled the questionnaire. Most pipelines are free for noncommercial use (n = 18) and work with the standard NIfTI (Neuroimaging Informatics Technology Initiative) data format (n = 15). All pipelines can process standard 3D single postlabeling delay pseudo‐continuous ASL images and primarily differ in their support of advanced sequences and features. The publicly available pipelines (n = 9) were included in the independent testing, all of them being free for noncommercial use. The pipelines, in general, provided a trade‐off between ease of use and flexibility for configuring advanced processing options. Conclusion: Although most ASL pipelines can process the common ASL data types, only some (namely, ASLPrep, ASLtbx, BASIL/Quantiphyse, ExploreASL, and MRICloud) are well‐documented, publicly available, support multiple ASL types, have a user‐friendly interface, and can provide a useful starting point for ASL processing. The choice of an optimal pipeline should be driven by specific data to be processed and user experience, and can be guided by the information provided in this ASL inventory. [ABSTRACT FROM AUTHOR]

This manuscript describes the ISMRM OSIPI (Open Science Initiative for Perfusion Imaging) lexicon for dynamic contrast‐enhanced and dynamic susceptibility‐contrast MRI. The lexicon was developed by Taskforce 4.2 of OSIPI to provide standardized definitions of commonly used quantities, models, and analysis processes with the aim of reducing reporting variability. The taskforce was established in February 2020 and consists of medical physicists, engineers, clinicians, data and computer scientists, and DICOM (Digital Imaging and Communications in Medicine) standard experts. Members of the taskforce collaborated via a slack channel and quarterly virtual meetings. Members participated by defining lexicon items and reporting formats that were reviewed by at least two other members of the taskforce. Version 1.0.0 of the lexicon was subject to open review from the wider perfusion imaging community between January and March 2022, and endorsed by the Perfusion Study Group of the ISMRM in the summer of 2022. The initial scope of the lexicon was set by the taskforce and defined such that it contained a basic set of quantities, processes, and models to enable users to report an end‐to‐end analysis pipeline including kinetic model fitting. We also provide guidance on how to easily incorporate lexicon items and definitions into free‐text descriptions (e.g., in manuscripts and other documentation) and introduce an XML‐based pipeline encoding format to encode analyses using lexicon definitions in standardized and extensible machine‐readable code. The lexicon is designed to be open‐source and extendable, enabling ongoing expansion of its content. We hope that widespread adoption of lexicon terminology and reporting formats described herein will increase reproducibility within the field. [ABSTRACT FROM AUTHOR]

The 2015 consensus statement published by the International Society for Magnetic Resonance in Medicine (ISMRM) Perfusion Study Group and the European Cooperation in Science and Technology (COST) Action ASL in Dementia aimed to encourage the implementation of robust arterial spin labeling (ASL) perfusion MRI for clinical applications and promote consistency across scanner types, sites, and studies. Subsequently, the recommended 3D pseudo‐continuous ASL sequence has been implemented by most major MRI manufacturers. However, ASL remains a rapidly and widely developing field, leading inevitably to further divergence of the technique and its associated terminology, which could cause confusion and hamper research reproducibility. On behalf of the ISMRM Perfusion Study Group, and as part of the ISMRM Open Science Initiative for Perfusion Imaging (OSIPI), the ASL Lexicon Task Force has been working on the development of an ASL Lexicon and Reporting Recommendations for perfusion imaging and analysis, aiming to (1) develop standardized, consensus nomenclature and terminology for the broad range of ASL imaging techniques and parameters, as well as for the physiological constants required for quantitative analysis; and (2) provide a community‐endorsed recommendation of the imaging parameters that we encourage authors to include when describing ASL methods in scientific reports/papers. In this paper, the sequences and parameters in (pseudo‐)continuous ASL, pulsed ASL, velocity‐selective ASL, and multi‐timepoint ASL for brain perfusion imaging are included. However, the content of the lexicon is not intended to be limited to these techniques, and this paper provides the foundation for a growing online inventory that will be extended by the community as further methods and improvements are developed and established. [ABSTRACT FROM AUTHOR]

Purpose: Software has a substantial impact on quantitative perfusion MRI values. The lack of generally accepted implementations, code sharing and transparent testing reduces reproducibility, hindering the use of perfusion MRI in clinical trials. To address these issues, the ISMRM Open Science Initiative for Perfusion Imaging (OSIPI) aimed to establish a community‐led, centralized repository for sharing open‐source code for processing contrast‐based perfusion imaging, incorporating an open‐source testing framework. Methods: A repository was established on the OSIPI GitHub website. Python was chosen as the target software language. Calls for code contributions were made to OSIPI members, the ISMRM Perfusion Study Group, and publicly via OSIPI websites. An automated unit‐testing framework was implemented to evaluate the output of code contributions, including visual representation of the results. Results: The repository hosts 86 implementations of perfusion processing steps contributed by 12 individuals or teams. These cover all core aspects of DCE‐ and DSC‐MRI processing, including multiple implementations of the same functionality. Tests were developed for 52 implementations, covering five analysis steps. For T1 mapping, signal‐to‐concentration conversion and population AIF functions, different implementations resulted in near‐identical output values. For the five pharmacokinetic models tested (Tofts, extended Tofts‐Kety, Patlak, two‐compartment exchange, and two‐compartment uptake), differences in output parameters were observed between contributions. Conclusions: The OSIPI DCE‐DSC code repository represents a novel community‐led model for code sharing and testing. The repository facilitates the re‐use of existing code and the benchmarking of new code, promoting enhanced reproducibility in quantitative perfusion imaging. [ABSTRACT FROM AUTHOR]

Background: MRI can provide information on kidney structure, perfusion, and oxygenation. Furthermore, it allows for the assessment of kidney sodium concentrations and handling, allowing multiparametric evaluation of kidney physiology. Multiparametric MRI is promising for establishing prognosis and monitoring treatment responses in kidney diseases, but its intraindividual variation during the day is unresolved. Purpose: To investigate the variation in multiparametric MRI measurements from the morning to the evening. Study Type: Prospective. Population: Ten healthy volunteers, aged 29 ± 5 without history of kidney disease. Field Strength/Sequence: 3 T/T1 mapping, blood‐oxygen level dependent imaging, arterial spin labeling perfusion imaging, diffusion weighted imaging, and sodium imaging. Assessment: A multiparametric MRI protocol, yielding T1, R2*, ADC, renal blood flow and renal sodium levels, was acquired in the morning, noon, and evening. The participants were fasting prior to the first examination. Urine biochemical analyses were performed to complement MRI data. The cortex and medulla were analyzed separately in a semi‐automatic fashion, and gradients of total sodium concentration (TSC) and R2* gradients were calculated from outer cortex to inner medulla. Statistical Test: Analyses of variance and mixed‐effects models to estimate differences from time of day. Coefficients of variation to assess variability within and between participants. A P‐value <0.05 was considered statistically significant. Results: The coefficients of variation varied from 5% to 18% for proton‐based parametric sequences, while it was 38% for TSC over a day. Data Conclusion: Multiparametric MRI is stable over the day. The coefficients of variation over a day were lower for proton multiparametric MRI, but higher for sodium MRI. Evidence Level: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Aims Systemic sclerosis (SSc) is characterized by vasculopathy, inflammation, and fibrosis, and carries one of the worst prognoses if patients also develop pulmonary arterial hypertension (PAH). Although PAH is a known prognosticator, patients with SSc–PAH demonstrate disproportionately high mortality, presumably due to cardiac involvement. In this cross-sectional study, the relationship between cardiac involvement revealed by cardiovascular magnetic resonance (CMR) and systemic microvascular disease severity measured with nailfold capillaromicroscopy (NCM) in patients with SSc–PAH is evaluated and compared with patients with idiopathic PAH (IPAH). Methods and results Patients with SSc–PAH and IPAH underwent CMR, echocardiography, and NCM with post-occlusive reactivity hyperaemia (PORH) testing on the same day. CMR imaging included T2 (oedema), native, and post-contrast T1 mapping to measure the extracellular volume fraction (ECV, fibrosis) and adenosine-stress-perfusion imaging measuring the relative myocardial upslope (microvascular coronary perfusion). Measures of peripheral microvascular function were related to CMR indices of oedema, fibrosis, and myocardial perfusion. SSc-PAH patients (n = 20) had higher T2 values and a trend towards a higher ECV, compared with IPAH patients (n = 5), and a lower nailfold capillary density (NCD) and reduced capillary recruitment after PORH. NCD correlated with ECV and T2 (r = −0.443 and −0.464, respectively, P < 0.05 for both) and with markers of diastolic dysfunction on echocardiography. PORH testing, but not NCD, correlated with the relative myocardial upslope (r = 0.421, P < 0.05). Conclusion SSc-PAH patients showed higher markers of cardiac fibrosis and inflammation, compared with IPAH patients. These markers correlated well with peripheral microvascular dysfunction, suggesting that SSc-driven inflammation and vasculopathy concurrently affect peripheral microcirculation and the heart. This may contribute to the disproportionate high mortality in SSc–PAH. [ABSTRACT FROM AUTHOR]

Aims To characterize acute lesions during cardiac magnetic resonance (CMR)-guided radiofrequency (RF) ablation of cavo-tricuspid isthmus (CTI)-dependent atrial flutter by combining T2-weighted imaging (T2WI), T1 mapping, first-pass perfusion, and late gadolinium enhancement (LGE) imaging. CMR-guided catheter ablation offers a unique opportunity to investigate acute ablation lesions. Until present, studies only used T2WI and LGE CMR to assess acute lesions. Methods and results Fifteen patients with CTI-dependent atrial flutter scheduled for CMR-guided RF ablation were prospectively enrolled. Directly after achieving bidirectional block of the CTI line, CMR imaging was performed using: T2WI (n = 15), T1 mapping (n = 10), first-pass perfusion (n = 12), and LGE (n = 12) imaging. In case of acute reconnection, additional RF ablation was performed. In all patients, T2WI demonstrated oedema in the ablation region. Right atrial T1 mapping was feasible and could be analysed with a high inter-observer agreement (r = 0.931, ICC 0.921). The increase in T1 values post-ablation was significantly lower in regions showing acute reconnection compared with regions without reconnection [37 ± 90 ms vs. 115 ± 69 ms (P = 0.014), and 3.9 ± 9.0% vs. 11.1 ± 6.8% (P = 0.022)]. Perfusion defects were present in 12/12 patients. The LGE images demonstrated hyper-enhancement with a central area of hypo-enhancement in 12/12 patients. Conclusion Tissue characterization of acute lesions during CMR-guided CTI-dependent atrial flutter ablation demonstrates oedema, perfusion defects, and necrosis with a core of microvascular damage. Right atrial T1 mapping is feasible, and may identify regions of acute reconnection that require additional RF ablation. [ABSTRACT FROM AUTHOR]

Objective: Alzheimer's disease, an irreversible neurological condition, demands timely diagnosis for effective clinical intervention. This study employs radiomics analysis to assess image features in default mode network cerebral perfusion imaging among individuals with cognitive impairment. Methods: A radiomics analysis of cerebral perfusion imaging was conducted on 117 patients with cognitive impairment. They were divided into training and validation sets in a 7:3 ratio. Least Absolute Shrinkage and Selection Operator (LASSO) and Random Forest were employed to select and model image features, followed by logistic regression analysis of LASSO and Random Forest results. Diagnostic performance was assessed by calculating the area under the curve (AUC). Results: In the training set, LASSO achieved AUC of 0.978, Random Forest had an AUC of 0.933. In the validation set, LASSO had AUC of 0.859, Random Forest had AUC of 0.986. By conducting Logistic Regression analysis in combination with LASSO and Random Forest, we identified a total of five radiomics features, with four related to morphology and one to textural features, originating from the medial prefrontal cortex and middle temporal gyrus. In the training set, Logistic Regression achieved AUC of 0.911, while in the validation set, it attained AUC of 0.925. Conclusion: The medial prefrontal cortex and middle temporal gyrus are the two brain regions within the default mode network that hold the highest significance for Alzheimer's disease diagnosis. Radiomics analysis contributes to the clinical assessment of Alzheimer's disease by delving into image data to extract deeper layers of information. [ABSTRACT FROM AUTHOR]

This study clinically implemented a ready-to-use quantitative perfusion (QP) cardiovascular magnetic resonance (QP CMR) workflow, encompassing a simplified dual-bolus gadolinium-based contrast agent (GBCA) administration scheme and fully automated QP image post-processing. Twenty-five patients with suspected obstructive coronary artery disease (CAD) underwent both adenosine stress perfusion CMR and an invasive coronary angiography or coronary computed tomography angiography. The dual-bolus protocol consisted of a pre-bolus (0.0075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) and a main bolus (0.075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) at an infusion rate of 3 ml/s. The arterial input function curves showed excellent quality. Stress MBF ≤ 1.84 ml/g/min accurately detected obstructive CAD (area under the curve 0.79; 95% Confidence Interval: 0.66 to 0.89). Combined visual assessment of color pixel QP maps and conventional perfusion images yielded a diagnostic accuracy of 84%, sensitivity of 70% and specificity of 93%. The proposed easy-to-use dual-bolus QP CMR workflow provides good image quality and holds promise for high accuracy in diagnosis of obstructive CAD. Implementation of this approach has the potential to serve as an alternative to current methods thus increasing the accessibility to offer high-quality QP CMR imaging by a wide range of CMR laboratories. [ABSTRACT FROM AUTHOR]

Background: Endovascular treatment (EVT) is effective for large vessel occlusion (LVO) stroke with smaller volumes of CT perfusion (CTP)-defined core. However, the influence of perfusion imaging during thrombectomy on the functional outcomes of patients with large ischemic core (LIC) stroke at both early and late time windows is uncertain in real-world practice. Method: A retrospective analysis was performed on 99 patients who underwent computed tomography angiography (CTA) and CT perfusion (CTP)-Rapid Processing of Perfusion and Diffusion (RAPID) before EVT and had a baseline ischemic core ≥ 50 mL and/or Alberta Stroke Program Early CT Score (ASPECTS) score of 0–5. The primary outcome was the three-month modified Rankin Scale (mRS) score. Data were analyzed by binary logistic regression and receiver operating characteristic (ROC) curves. Results: A fair outcome (mRS, 0–3) was found in 34 of the 99 patients while 65 had a poor prognosis (mRS, 4–6). The multivariate logistic regression analysis showed that onset-to-reperfusion (OTR) time (odds ratio [OR], 1.004; 95% confidence interval [CI], 1.001–1.007; p = 0.008), ischemic core (OR, 1.066; 95% CI, 1.024–1.111; p = 0.008), and the hypoperfusion intensity ratio (HIR) (OR, 70.898; 95% CI, 1.130-4450.152; p = 0.044) were independent predictors of outcome. The combined results of ischemic core, HIR, and OTR time showed good performance with an area under the ROC curve (AUC) of 0.937, significantly higher than the individual variables (p < 0.05) using DeLong's test. Conclusions: Higher HIR and longer OTR time in large core stroke patients were independently associated with unfavorable three-month outcomes after EVT. [ABSTRACT FROM AUTHOR]

Purpose: To explore the relationship between obstructive sleep apnea (OSA) and hypoperfusion during ultra-early acute cerebral infarction. Patients and methods: Data were retrospectively collected from patients admitted to our hospital with acute cerebral infarction between January 2020 and January 2022, who underwent comprehensive whole-brain computed tomography perfusion imaging and angiography examinations within 6 h of onset. The F-stroke software automatically assessed and obtained relevant data (Tmax). The patients underwent an initial screening for sleep apnea. Based on their Apnea-Hypopnea Index (AHI), patients were categorized into an AHI ≤15 (n = 22) or AHI >15 (n = 25) group. The pairwise difference of the time-to-maximum of the residue function (Tmax) > 6 s volume was compared, and the correlation between AHI, mean pulse oxygen saturation (SpO2), oxygen desaturation index (ODI), percentage of time with oxygen saturation < 90% (T90%), and the Tmax >6 s volume was analyzed. Results: The Tmax >6 s volume in the AHI > 15 group was significantly larger than that in the AHI ≤ 15 group [109 (62–157) vs. 59 (21–106) mL, p = 0.013]. Spearman’s correlation analysis revealed Tmax >6 s volume was significantly correlated with AHI, mean SpO2, ODI, and T90% in the AHI > 15 group, however, no significant correlations were observed in the AHI ≤ 15 group. Controlling for the site of occlusion and Multiphase CT angiography (mCTA) score, AHI (β = 0.919, p < 0.001), mean SpO2 (β = −0.460, p = 0.031), ODI (β = 0.467, p = 0.032), and T90% (β =0.478, p = 0.026) remained associated with early hypoperfusion in the AHI > 15 group. Conclusion: In patients with acute cerebral infarction and AHI > 15, AHI, mean SpO2, ODI and T90% were associated with early hypoperfusion. However, no such relationship exists among patients with AHI ≤ 15. [ABSTRACT FROM AUTHOR]

Background and Aim: Accurate interpretation of post-treatment imaging in head and neck malignancies poses a challenge due to treatment sequelae. Magnetic resonance (MR) perfusion helps in this scenario by evaluating the hemodynamic characteristics of lesions. This study aimed to elucidate the diagnostic efficacy of dynamic contrast-enhanced (DCE)-MR perfusion imaging in detecting recurrence in patients after they underwent definitive treatment for head and neck tumors. Materials and Methods: Thirty patients who had received definitive curative-intent treatment for histopathology-proven malignant head and neck tumors and in whom recurrent tumor was detected on precontrast MR imaging (MRI) were accrued in the study. Patients underwent DCE-MR perfusion imaging. Time to peak (TTP), relative maximum enhancement (RME), and relative washout (RWO) ratio were calculated by using time-intensity curve (TIC). The diagnostic accuracy was compared with histopathology. Results: A cut-off value of ≥125.3 for RME showed a sensitivity of 76.2% and specificity of 66.7% for differentiating post-radiation changes and recurrence. The optimal cut-off for RWO ratio was ≥-6.24 with a sensitivity of 76.2% and specificity of 55.6%. The optimal cut-off of TTP was ≤45.8 s with a sensitivity of 61.9% and specificity of 77.8%. Diagnostic accuracies of RME, RWO, and TTP were 73.3%, 70%, and 66.7%, respectively. Conclusions: DCE-MRI had significant diagnostic accuracy in detecting and differentiating recurrences. TIC analysis of high-temporal resolution DCE-MRI can provide information regarding microcirculation of tumors, and hence can be considered as an imaging modality of choice for assessment of early local tumor recurrence in head and neck tumors. [ABSTRACT FROM AUTHOR]

Pretreatment CT Perfusion (CTP) parameter rCBV < 42% lesion volume has recently been shown to predict 90-day mRS. In this study, we aim to assess the relationship between rCBV < 42% and a radiographic follow-up infarct volume delineated on FLAIR images. In this retrospective evaluation of our prospectively collected database, we included acute stroke patients triaged by multimodal CT imaging, including CT angiography and perfusion imaging, with confirmed anterior circulation large vessel occlusion between 9 January 2017 and 10 January 2023. Follow-up FLAIR imaging was used to determine the final infarct volume. Student t, Mann-Whitney-U, and Chi-Square tests were used to assess differences. Spearman's rank correlation and linear regression analysis were used to assess associations between rCBV < 42% and follow-up infarct volume on FLAIR. In total, 158 patients (median age: 68 years, 52.5% female) met our inclusion criteria. rCBV < 42% (ρ = 0.56, p < 0.001) significantly correlated with follow-up-FLAIR infarct volume. On multivariable linear regression analysis, rCBV < 42% lesion volume (beta = 0.60, p < 0.001), ASPECTS (beta = −0.214, p < 0.01), mTICI (beta = −0.277, p < 0.001), and diabetes (beta = 0.16, p < 0.05) were independently associated with follow-up infarct volume. The rCBV < 42% lesion volume is independently associated with FLAIR follow-up infarct volume. [ABSTRACT FROM AUTHOR]

Cerebral ischemia has a high morbidity and disability rate. Clinical diagnosis is mainly made by radiologists manually reviewing cerebral perfusion images to determine whether cerebral ischemia is present. The number of patients with cerebral ischemia has risen dramatically in recent years, which has brought a huge workload for radiologists. In order to improve the efficiency of diagnosis, we develop a neural network for segmenting cerebral ischemia regions in perfusion images. Combining deep learning with medical imaging technology, we propose a segmentation network, UTAC-Net, based on U-Net and Transformer, which includes a contour-aware module and an attention branching fusion module, to achieve accurate segmentation of cerebral ischemic regions and correct identification of ischemic locations. Cerebral ischemia datasets are scarce, so we built a relevant dataset. The results on the self-built dataset show that UTAC-Net is superior to other networks, with the mDice of UTAC-Net increasing by 9.16% and mIoU increasing by 14.06% compared with U-Net. The output results meet the needs of aided diagnosis as judged by radiologists. Experiments have demonstrated that our algorithm has higher segmentation accuracy than other algorithms and better assists radiologists in the initial diagnosis, thereby reducing radiologists' workload and improving diagnostic efficiency. [ABSTRACT FROM AUTHOR]

Computed tomography perfusion (CTP) is a dynamic 4-dimensional imaging technique (3-dimensional volumes captured over approximately 1 min) in which cerebral blood flow is quantified by tracking the passage of a bolus of intravenous contrast with serial imaging of the brain. To diagnose and assess acute ischemic stroke, the standard method relies on summarizing acquired CTPs over the time axis to create maps that show different hemodynamic parameters, such as the timing of the bolus arrival and passage (Tmax and MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV). However, producing accurate CTP maps requires the selection of an arterial input function (AIF), i.e. a time-concentration curve in one of the large feeding arteries of the brain, which is a highly error-prone procedure. Moreover, during approximately one minute of CT scanning, the brain is exposed to ionizing radiation that can alter tissue composition, and create free radicals that increase the risk of cancer. This paper proposes a novel end-to-end deep neural network that synthesizes CTP images to generate CTP maps using a learned LSTM Generative Adversarial Network (LSTM-GAN). Our proposed method can improve the precision and generalizability of CTP map extraction by eliminating the error-prone and expert-dependent AIF selection step. Further, our LSTM-GAN does not require the entire CTP time series and can produce CTP maps with a reduced number of time points. By reducing the scanning sequence from about 40 to 9 time points, the proposed method has the potential to minimize scanning time thereby reducing patient exposure to CT radiation. Our evaluations using the ISLES 2018 challenge dataset consisting of 63 patients showed that our model can generate CTP maps by using only 9 snapshots, without AIF selection, with an accuracy of 84.37 % . [ABSTRACT FROM AUTHOR]

Background and Purpose: Recent endovascular trials have spurred a paradigm shift toward routine use of CT perfusion (CTP) for decision-making in acute ischemic stroke. CTP use in the late window, however, remains under evaluation. Our objective was to assess the accuracy of CTP-predicted core in the late window. Methods: In a retrospective review of our prospectively identified stroke registry at a single, comprehensive stroke center, we included patients with anterior large vessel occlusions presenting within the 6-24 h window who underwent baseline CTP evaluation and achieved TICI2b or TICI3 reperfusion on endovascular treatment. We recorded baseline CTP-predicted core volumes at relative cerebral blood flow (CBF) thresholds of <30% <34%, and <38% using RAPID software. Final infarct volumes (FIV) were calculated using follow up MRI and CT, obtained within 72 h after stroke onset. Results: Of the eligible patients, 134 met our inclusion criteria. Mean FIV was 39.5 (SD 49.6). Median CTP to reperfusion time was 93.5 min. Median absolute differences between CTP-predicted core and FIV were 14.7, 14.9, and 16.0 ml at <30%, <34%, and <38%, respectively. Correlation between CTP-predicted ischemic cores and FIV was moderate and statistically significant at all thresholds: r = 0.43 (p <0.001), r = 0.43 (p <0.001), and r = 0.42 (p <0.001) at the <30%, <34%, and <38% cutoffs, respectively. Conclusion: CTP cores in the 6–24 h period underestimate FIV, especially with larger infarcts. CTP-predicted core volumes in the late window show moderate positive correlation with FIV. [ABSTRACT FROM AUTHOR]

Simple Summary: Magnetic resonance imaging is an invaluable tool for the diagnosis of brain diseases in veterinary medicine. In this review, we provide a comprehensive summary of the magnetic resonance imaging appearances of and diagnostic approach to brain tumors affecting dogs and cats. Characteristic imaging features often allow for accurate prediction of commonly encountered types of brain tumors in clinical practice, such as meningiomas, gliomas, and pituitary tumors. However, a limitation of magnetic resonance imaging remains that some types of brain tumors, as well as other causes of brain disease, display similar imaging features, which can lead to diagnostic uncertainty and errors. There are also several uncommon to rare variants of brain tumors for which published magnetic resonance imaging descriptions are extremely limited or non-existent, especially in cats. The recent development and clinical usage of quantitative imaging and artificial intelligence techniques show promise for improving the ability of magnetic resonance imaging to correctly diagnose brain tumors and discriminate different tumor types. Magnetic resonance imaging (MRI) is used pervasively in veterinary practice for the antemortem diagnosis of intracranial tumors. Here, we provide an illustrated summary of the published MRI features of primary and secondary intracranial tumors of dogs and cats, following PRISMA scoping review guidelines. The PubMed and Web of Science databases were searched for relevant records, and input from stakeholders was solicited to select data for extraction. Sixty-seven studies of moderate to low-level evidence quality describing the MRI features of pathologically confirmed canine and feline brain tumors met inclusion criteria. Considerable variability in data inclusion and reporting, as well as low case numbers, prohibited comparative data analyses. Available data support a holistic MRI approach incorporating lesion number, location within the brain, shape, intrinsic signal appearances on multiparametric sequences, patterns of contrast enhancement, and associated secondary changes in the brain to prioritize differential imaging diagnoses, and often allows for accurate presumptive diagnosis of common intracranial tumors. Quantitative MRI techniques show promise for improving discrimination of neoplastic from non-neoplastic brain lesions, as well as differentiating brain tumor types and grades, but sample size limitations will likely remain a significant practical obstacle to the design of robustly powered radiomic studies. For many brain tumor variants, particularly in cats, there remains a need for standardized studies that correlate clinicopathologic and neuroimaging data. [ABSTRACT FROM AUTHOR]

Purpose: To determine if hepatic and splenic perfusion parameters are useful in identifying severe portal hypertension (SPH). Methods: The study enrolled 52 patients who underwent perfusion CT scan within one week before the hepatic venous pressure gradient (HVPG) measurement. A commercial software package was used for post-processing to generate hepatic and splenic perfusion parameters. Correlations were assessed using Pearson and Spearman rank correlation coefficients. Logistic regression was used to screen predictive parameters of SPH. The cut-off values of parameters for severe portal hypertension were calculated, as well as the sensitivity and specificity. Results: There was a significant difference between SPH and non-severe portal hypertension (NSPH) in blood volume of liver (BVLiver), hepatic arterial fraction (HAF), hepatic arterial perfusion (HAP), portal venous perfusion (PVP), mean slope of increase in spleen (MSISpleen), BVSpleen, blood flow of spleen (BFSpleen), BVSpleen/Liver, and BVSpleen/Liver(P) (p < 0.05). The Spearman correlation coefficient was − 0.541 (p < 0.001) between BVSpleen/Live and HVPG and − 0.568 (p < 0.001) between BVSpleen/Liver(P) and HVPG. Using a BVSpleen/Liver value of 0.780 or BVSpleen/Liver(P) value of 1.061 as the cut-off value for the detection of SPH, the sensitivity and specificity were 94.7% and 72.7%, 100%, and 63.6% respectively. Conclusion: There was a moderate correlation between CT perfusion parameters BVSpleen/Liver, BVSpleen/Liver(P), and HVPG, which may be used to detect severe portal hypertension. [ABSTRACT FROM AUTHOR]