CT Perfusion Imaging Research Articles

Standardizing the estimation of ischemic regions can harmonize CT perfusion stroke imaging

ObjectivesWe aimed to evaluate the real-world variation in CT perfusion (CTP) imaging protocols among stroke centers and to explore the potential for standardizing vendor software to harmonize CTP images.MethodsStroke centers participating in a nationwide multicenter healthcare evaluation were requested to share their CTP scan and processing protocol. The impact of these protocols on CTP imaging was assessed by analyzing data from an anthropomorphic phantom with center-specific vendor software with default settings from one of three vendors (A–C): IntelliSpace Portal, syngoVIA, and Vitrea. Additionally, standardized infarct maps were obtained using a logistic model.ResultsEighteen scan protocols were studied, all varying in acquisition settings. Of these protocols, seven, eight, and three were analyzed with center-specific vendor software A, B, and C respectively. The perfusion maps were visually dissimilar between the vendor software but were relatively unaffected by the acquisition settings. The median error [interquartile range] of the infarct core volumes (mL) estimated by the vendor software was − 2.5 [6.5] (A)/ − 18.2 [1.2] (B)/ − 8.0 [1.4] (C) when compared to the ground truth of the phantom (where a positive error indicates overestimation). Taken together, the median error [interquartile range] of the infarct core volumes (mL) was − 8.2 [14.6] before standardization and − 3.1 [2.5] after standardization.ConclusionsCTP imaging protocols varied substantially across different stroke centers, with the perfusion software being the primary source of differences in CTP images. Standardizing the estimation of ischemic regions harmonized these CTP images to a degree.Clinical relevance statementThe center that a stroke patient is admitted to can influence the patient’s diagnosis extensively. Standardizing vendor software for CT perfusion imaging can improve the consistency and accuracy of results, enabling a more reliable diagnosis and treatment decision.Key Points• CT perfusion imaging is widely used for stroke evaluation, but variation in the acquisition and processing protocols between centers could cause varying patient diagnoses.• Variation in CT perfusion imaging mainly arises from differences in vendor software rather than acquisition settings, but these differences can be reconciled by standardizing the estimation of ischemic regions.• Standardizing the estimation of ischemic regions can improve CT perfusion imaging for stroke evaluation by facilitating reliable evaluations independent of the admission center.

Electrical Impedance Tomography Identifies Evolution of Regional Perfusion in a Porcine Model of Acute Respiratory Distress Syndrome.

Bedside electrical impedance tomography could be useful to visualize evolving pulmonary perfusion distributions when acute respiratory distress syndrome worsens or in response to ventilatory and positional therapies. In experimental acute respiratory distress syndrome, this study evaluated the agreement of electrical impedance tomography and dynamic contrast-enhanced computed tomography perfusion distributions at two injury time points and in response to increased positive end-expiratory pressure (PEEP) and prone position. Eleven mechanically ventilated (VT 8 ml · kg-1) Yorkshire pigs (five male, six female) received bronchial hydrochloric acid (3.5 ml · kg-1) to invoke lung injury. Electrical impedance tomography and computed tomography perfusion images were obtained at 2 h (early injury) and 24 h (late injury) after injury in supine position with PEEP 5 and 10 cm H2O. In eight animals, electrical impedance tomography and computed tomography perfusion imaging were also conducted in the prone position. Electrical impedance tomography perfusion (QEIT) and computed tomography perfusion (QCT) values (as percentages of image total) were compared in eight vertical regions across injury stages, levels of PEEP, and body positions using mixed-effects linear regression. The primary outcome was agreement between QEIT and QCT, defined using limits of agreement and Pearson correlation coefficient. Pao2/Fio2 decreased over the course of the experiment (healthy to early injury, -253 [95% CI, -317 to -189]; early to late injury, -88 [95% CI, -151 to -24]). The limits of agreement between QEIT and QCT were -4.66% and 4.73% for the middle 50% quantile of average regional perfusion, and the correlation coefficient was 0.88 (95% CI, 0.86 to 0.90]; P < 0.001). Electrical impedance tomography and computed tomography showed similar perfusion redistributions over injury stages and in response to increased PEEP. QEIT redistributions after positional therapy underestimated QCT in ventral regions and overestimated QCT in dorsal regions. Electrical impedance tomography closely approximated computed tomography perfusion measures in experimental acute respiratory distress syndrome, in the supine position, over injury progression and with increased PEEP. Further validation is needed to determine the accuracy of electrical impedance tomography in measuring perfusion redistributions after positional changes.

CT perfusion imaging parameters and serum miR-106a-5p predict short- and long-term prognosis in acute cerebral infarction patients after intravenous thrombolysis.

Some microRNAs have been found to be abnormal in patients with acute cerebral infarction (ACI) after intravenous thrombolysis. This study aimed to measure the expression of miR-106a-5p in ACI patients before and after thrombolytic treatment, and to investigate the prognostic value of miR-106a-5p and computed tomography perfusion imaging (CTPI) parameters in ACI patients receiving thrombolysis. The levels of serum miR-106a-5p were detected by quantitative real-time PCR in 78 ACI patients before thrombolysis, 24 hours after thrombolysis, and 3 months (90 days) after onset. The correlation of miR-106a-5p with continuous variables were analyzed using Pearson correlation analysis. The association of miR-106a-5p and CTPI parameters with prognosis of patients receiving thrombolysis was evaluated by logistic regression analysis. The accuracy and thresholds of miR-106a-5p and CTPI parameters for discriminating patients with unfavorable prognosis after thrombolysis were assessed by receiver operating characteristic analysis. Serum miR-106a-5p expression was decreased in ACI patient after thrombolysis. Then, significant correlations of miR-106a-5p with National Institutes of Health Stroke Scale and CTPI parameters were found. Moreover, miR-106a-5p, cerebral blood flow (CBF) and cerebral blood volume (CBV), which are 2 CTPI parameters, were independently correlated with short- and long-term prognosis after thrombolysis. Furthermore, miR-106a-5p, CBF and CBV revealed good accuracy in predicting the prognosis of patients after thrombolysis, and their combination showed the best accuracy. Thrombolysis downregulates miR-106a-5p in ACI patients, and miR-106a-5p, CBF and CBV have considerable potentials to predict short- and long-term prognosis in ACI patients receiving intravenous thrombolysis.

Diagnosis of Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage and Triggers for Intervention

IntroductionDelayed cerebral ischemia (DCI) is a major determinant for poor neurological outcome after aneurysmal subarachnoid hemorrhage (aSAH). Detection and treatment of DCI is a key component in the neurocritical care of patients with aSAH after initial aneurysm repair.MethodsNarrative review of the literature.ResultsOver the past 2 decades, there has been a paradigm shift away from macrovascular (angiographic) vasospasm as a main diagnostic and therapeutic target. Instead, the pathophysiology of DCI is hypothesized to derive from several proischemic pathomechanisms. Clinical examination remains the most reliable means for monitoring and treatment of DCI, but its value is limited in comatose patients. In such patients, monitoring of DCI is usually based on numerous neurophysiological and/or radiological diagnostic modalities. Catheter angiography remains the gold standard for the detection of macrovascular spasm. Computed tomography (CT) angiography is increasingly used instead of catheter angiography because it is less invasive and may be combined with CT perfusion imaging. CT perfusion permits semiquantitative cerebral blood flow measurements, including the evaluation of the microcirculation. It may be used for prediction, early detection, and diagnosis of DCI, with yet-to-prove benefit on clinical outcome when used as a screening modality. Transcranial Doppler may be considered as an additional noninvasive screening tool for flow velocities in the middle cerebral artery, with limited accuracy in other cerebral arteries. Continuous electroencephalography enables detection of early signs of ischemia at a reversible stage prior to clinical manifestation. However, its widespread use is still limited because of the required infrastructure and expertise in data interpretation. Near-infrared spectroscopy, a noninvasive and continuous modality for evaluation of cerebral blood flow dynamics, has shown conflicting results and needs further validation. Monitoring techniques beyond neurological examinations may help in the detection of DCI, especially in comatose patients. However, these techniques are limited because of their invasive nature and/or restriction of measurements to focal brain areas.ConclusionThe current literature review underscores the need for incorporating existing modalities and developing new methods to evaluate brain perfusion, brain metabolism, and overall brain function more accurately and more globally.

Reduction of scan duration and radiation dose in cerebral CT perfusion imaging of acute stroke using a recurrent neural network

Objective. Cerebral CT perfusion (CTP) imaging is most commonly used to diagnose acute ischaemic stroke and support treatment decisions. Shortening CTP scan duration is desirable to reduce the accumulated radiation dose and the risk of patient head movement. In this study, we present a novel application of a stochastic adversarial video prediction approach to reduce CTP imaging acquisition time. Approach. A variational autoencoder and generative adversarial network (VAE-GAN) were implemented in a recurrent framework in three scenarios: to predict the last 8 (24 s), 13 (31.5 s) and 18 (39 s) image frames of the CTP acquisition from the first 25 (36 s), 20 (28.5 s) and 15 (21 s) acquired frames, respectively. The model was trained using 65 stroke cases and tested on 10 unseen cases. Predicted frames were assessed against ground-truth in terms of image quality and haemodynamic maps, bolus shape characteristics and volumetric analysis of lesions. Main results. In all three prediction scenarios, the mean percentage error between the area, full-width-at-half-maximum and maximum enhancement of the predicted and ground-truth bolus curve was less than 4 ± 4%. The best peak signal-to-noise ratio and structural similarity of predicted haemodynamic maps was obtained for cerebral blood volume followed (in order) by cerebral blood flow, mean transit time and time to peak. For the 3 prediction scenarios, average volumetric error of the lesion was overestimated by 7%–15%, 11%–28% and 7%–22% for the infarct, penumbra and hypo-perfused regions, respectively, and the corresponding spatial agreement for these regions was 67%–76%, 76%–86% and 83%–92%. Significance. This study suggests that a recurrent VAE-GAN could potentially be used to predict a portion of CTP frames from truncated acquisitions, preserving the majority of clinical content in the images, and potentially reducing the scan duration and radiation dose simultaneously by 65% and 54.5%, respectively.

Application of Computed Tomography Perfusion Imaging-guided Mechanical Thrombectomy in Ischemic Stroke Patients with Large Vessel Occlusion beyond the Therapeutic Time Window.

To explore the feasibility of applying computed tomography perfusion (CTP) imaging-guided mechanical thrombectomy in acute ischemic stroke patients with large vessel occlusion beyond the therapeutic time window. The clinical data of acute cerebral infarction patients with large vessel occlusion who were beyond the therapeutic time window and admitted to Handan Central Hospital from January 2021 to March 2022 were retrospectively analyzed. All patients were assessed by the National Institutes of Health Stroke Scale (NIHSS) and were examined by one-stop CTP imaging. The preoperative onset time of the disease was more than 6 h. Fourteen patients underwent magnetic resonance imaging examination at the same time. Fifty-four patients were retrospectively divided into two groups based on the treatment methods: the mechanical thrombectomy group had 21 patients and the conservative treatment group had 33 patients. NIHSS scoring and computed tomography scan were performed before treatment, 6 h, 24 h, 7 days, and 30 days after treatment. The NIHSS scores of the patients with acute cerebral large vessel occlusion who underwent CTP imaging-guided mechanical thrombectomy at 6 h, 24 h, 7 days, and 30 days after treatment were compared with those of the conventional treatment group. The NIHSS score of the mechanical thrombectomy group was significantly better, and the difference was statistically significant (P < 0.05). In terms of the prognosis rate and expansion rate of infarct core volume, the patients of the mechanical thrombectomy group had a better prognosis, and the difference was statistically significant (P < 0.05). Artificial intelligence-assisted CTP diagnosis can facilitate the automatic evaluation of diseases and enable quick judgments that are independent of radiologists' evaluation, but it may pose a problem in the determination of infarct core volume (either being too high or too low). It is of great significance to apply CTP imaging in guiding the mechanical thrombectomy procedure in acute stroke patients with large vessel occlusion who are beyond the therapeutic time window.

Multivariate Analysis of Ischaemic Lesions Using Computed Tomography and CT Perfusion Imaging: Critical Review

ABSTRACT Stroke is characterised as a cerebrovascular disease, which acts as the key factor of mortality and permanent disabilities. Ischaemic stroke is observed as a widespread stroke that results in tissue hypoxia. Hence, it is crucial to analyse the ischaemic stroke lesions for the accurate identification of the stroke in intensive care units. However, the recognition of ischaemic lesions is a difficult process due to their small resolution and poor image resolution. Various schemes have been suggested for stroke lesion identification, localisation, and detection, finding infarct cores and penumbras is of high interest. Artificial intelligence could be one of the promising technologies in all methods, which may accelerate stroke analysis and lead to improved patient recovery. This article provides a review of different articles related to ischaemic lesion deduction using Computed Tomography (CT) and CT perfusion imaging. This review article thus provides insight into methods, performance measures, and the key highlight of these models. Further, this review article provides the challenges encountered in the existing techniques.

Prediction of response to thrombolysis in acute stroke using neural network analysis of CT perfusion imaging.

In ischaemic stroke patients undergoing reperfusion therapy, the amount of salvageable tissue, that is, extent of the ischaemic penumbra, predicts the clinical outcomes. CT perfusion (CTP) enables quantification of penumbral tissues to guide decision making, and current programmes have automated its analysis. More advanced machine learning techniques utilising the CTP maps may improve prediction beyond the ischaemic volume measures. We determined whether applying convolutional neural networks (CNN), a key machine learning technique in modelling image-label relationships, to post-processed CTP maps improved prediction of outcome, assessed by 3 months modified Rankin scale (mRS). Patients who underwent thrombolysis but not thrombectomy were included. CTP maps of a retrospective cohort of 230 patients with middle cerebral artery stroke were used to develop the model, which was validated in an independent cohort of 129 patients. We constructed a CNN model that predicted a favourable post-thrombolysis outcome (mRS 0-2 at 3 months) with an area under receiver-operator characteristics curve (AUC) of 0.792 (95% CI, 0.707-0.877). This model outperformed a currently clinically used MISTAR software using previously validated thresholds (AUC = 0.583, 95% CI, 0.480-0.686) and a model modified using thresholds from the derivation cohort (AUC = 0.670, 95% CI, 0.571-0.769). By combining CNN-derived features and baseline demographic features, the prediction AUC was improved to 0.865 (95% CI, 0.794-0.936). CNN improved prediction of post-thrombolysis outcome, and may be useful in selecting which patients benefit from thrombolysis.

Intraoperative computed tomography perfusion navigation for maximal resection of high grade gliomas: a prospective non-randomized trial

Background: The main purpose of surgery for glioblastoma is to ensure the maximally possible cytoreduction. Computed tomography perfusion imaging has non-invasive tools for assessment of tumor blood flow and allows for visualization of the tumor borders and its most malignant zones.&#x0D; Aim: To evaluate the efficacy of intraoperative computed tomography perfusion navigation (ICTPN) during surgery for high grade gliomas.&#x0D; Materials and methods: This prospective non-randomized study included 142 patients (76 men and 66 women) with morphologically verified diagnosis of glioblastoma or diffuse astrocytoma grade 4 (World Health Organization 2021 criteria), who had surgery from 2016 to 2022. The ICTPN-based procedures were performed in 94 patients, with 55 with gross total and 39 with subtotal tumor resection. The control group included 48 patients with non-ICTPN-based surgical procedures. All patients were treated with standard adjuvant chemoradiation therapy. The efficacy of surgery was assessed every 3 months. The study endpoint was any tumor progression. The duration of the follow-up was 15 months. Baseline and contrast-enhanced preoperative imaging and postoperative follow-up assessments were performed with a 3T magnetic resonance imaging scanner (General Electric Discovery W750). ICTPN was done with a 32 slice computed tomography scanner (Toshiba Aquilion LB).&#x0D; Results: In the totally resected ICTPN group, the mean duration of the relapse-free period was 13.05 months; the relapse-free survival at 6 and 12 months was 92 and 55%, respectively (p 0.001). These results were significantly better than those in the subtotally resected ICTPN patients (8.98 months, 66 and 9%, respectively; log rank test for Kaplan-Meier curves, p 0.001) and in non-ICTPN patients (5.81 months, 23 and 0%, respectively, log rank test, p 0.001).&#x0D; Conclusion: ICTPN enables a more objective assessment of the tumor borders and the extent of its resection, as well as relapse-free survival benefits for the patients.

The oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study

BackgroundCerebral autoregulation (CA) can be impaired in patients with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The Pressure Reactivity Index (PRx, correlation of blood pressure and intracranial pressure) and Oxygen Reactivity Index (ORx, correlation of cerebral perfusion pressure and brain tissue oxygenation, PbtO2) are both believed to estimate CA. We hypothesized that CA could be poorer in hypoperfused territories during DCI and that ORx and PRx may not be equally effective in detecting such local variances.MethodsORx and PRx were compared daily in 76 patients with aSAH with or without DCI until the time of DCI diagnosis. The ICP/PbtO2-probes of DCI patients were retrospectively stratified by being in or outside areas of hypoperfusion via CT perfusion image, resulting in three groups: DCI + /probe + (DCI patients, probe located inside the hypoperfused area), DCI + /probe− (probe outside the hypoperfused area), DCI− (no DCI).ResultsPRx and ORx were not correlated (r = − 0.01, p = 0.56). Mean ORx but not PRx was highest when the probe was located in a hypoperfused area (ORx DCI + /probe + 0.28 ± 0.13 vs. DCI + /probe− 0.18 ± 0.15, p < 0.05; PRx DCI + /probe + 0.12 ± 0.17 vs. DCI + /probe− 0.06 ± 0.20, p = 0.35). PRx detected poorer autoregulation during the early phase with relatively higher ICP (days 1–3 after hemorrhage) but did not differentiate the three groups on the following days when ICP was lower on average. ORx was higher in the DCI + /probe + group than in the other two groups from day 3 onward. ORx and PRx did not differ between patients with DCI, whose probe was located elsewhere, and patients without DCI (ORx DCI + /probe− 0.18 ± 0.15 vs. DCI− 0.20 ± 0.14; p = 0.50; PRx DCI + /probe− 0.06 ± 0.20 vs. DCI− 0.08 ± 0.17, p = 0.35).ConclusionsPRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx. Further research should investigate their robustness to detect DCI and to serve as a basis for autoregulation-targeted treatment after aSAH.

Rationale and design of Tenecteplase Reperfusion Therapy in Acute Ischaemic Cerebrovascular Events III (TRACE III): a randomised, phase III, open-label, controlled trial

Background and purposeRecombinant human TNK tissue-type plasminogen activator (rhTNK-tPA) was not inferior to alteplase for ischaemic stroke within 4.5 hours. Our study aimed to investigate the efficacy and safety of...

Hyperacute stenting and angioplasty for acute extracranial non-tandem internal carotid artery strokes within the first 48 h: A 20-year experience and a systematic review and meta-analysis.

Acute strokes involving complete, isolated occlusion of the extracranial cervical internal carotid artery (EC-ICA) with no intracranial clot burden account for a minority of stroke cases that are managed variably. Here we present our two-decade experience and a systematic review of endovascular management of acute isolated EC-ICA strokes in the hyperacute phase (<48 h) and attempt to evaluate clinical effectiveness and safety. Our prospectively maintained database was retrospectively searched for patients who presented between January 1, 2003 and December 31, 2022 with acute cervical ICA stroke confirmed on angiography. Only patients who had an isolated 100% occlusion of the cervical ICA segment and attempted acute stenting with/without angioplasty within the first 48 h of time since last known well were included. Demographics, procedural details, and outcomes were recorded. For the systematic review, a search of PubMed and Embase databases was conducted. Forty-six patients with acute, isolated EC-ICA occlusive stroke were included. Median presenting National Institutes of Health Stroke Scale (NIHSS) score was 8 (interquartile range 3-10) with a perfusion deficit in 78.3% of the 40 cases assessed with computed tomography perfusion imaging. Median time from symptom onset to intra-arterial puncture was 14.4 h. Immediate recanalization was achieved in 82.6% cases. Two cases (4.3%) of symptomatic intracranial hemorrhage (sICH) occurred postprocedure. Outcome measures were stable or improved discharge NIHSS score in 86.9% of cases, functional independence at 90 days (modified Rankin scale score ≤2) in 78.3%, and mortality in 6.5%. The systematic review included 167 patients from four articles. The estimated rate of immediate recanalization was 92.7% (95% confidence interval (CI), 88.77-96.77%), favorable outcome was 62.01% (95% CI, 55.04-69.87%), and sICH was 6.2% (95% CI, 3.41-11.32%). Stenting and angioplasty for acute cervical ICA occlusive strokes during the hyperacute phase can be performed successfully with favorable clinical outcomes and an acceptable recanalization rate.

Evaluation of MTT Heterogeneity of Perfusion CT Imaging in the Early Brain Injury Phase: An Insight into aSAH Pathopysiology.

The concept of early brain injury (EBI) is based on the assumption of a global reduction in brain perfusion following aneurysmal subarachnoid hemorrhage (aSAH). However, the heterogeneity of computed tomography perfusion (CTP) imaging in EBI has not yet been investigated. In contrast, increased mean transit time (MTT) heterogeneity, a possible marker of microvascular perfusion heterogeneity, in the delayed cerebral ischemia (DCI) phase has recently been associated with a poor neurological outcome after aSAH. Therefore, in this study, we investigated whether the heterogeneity of early CTP imaging in the EBI phase is an independent predictor of the neurological outcome after aSAH. We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation (cvMTT) in early CTP scans (within 24 h after ictus) of 124 aSAH patients. Both linear and logistic regression were used to model the mRS outcome, which were treated as numerical and dichotomized values, respectively. Linear regression was used to investigate the linear dependency between the variables. No significant difference in cvMTT between the patients with and those without EVD could be observed (p = 0.69). We found no correlation between cvMTT in early CTP imaging and initial modified Fisher (p = 0.07) and WFNS grades (p = 0.23). The cvMTT in early perfusion imaging did not correlate significantly with the 6-month mRS for the entire study population (p = 0.15) or for any of the subgroups (without EVD: p = 0.21; with EVD: p = 0.3). In conclusion, microvascular perfusion heterogeneity, assessed by the heterogeneity of MTT in early CTP imaging, does not appear to be an independent predictor of the neurological outcome 6 months after aSAH.

Artificial intelligence in cardiovascular imaging: enhancing image analysis and risk stratification.

In this review, we summarize state-of-the-art artificial intelligence applications for non-invasive cardiovascular imaging modalities including CT, MRI, echocardiography, and nuclear myocardial perfusion imaging.

Technical comparison of continuous versus intermittent perfusion computed tomography computed tomography scans of the human pancreas.

Pancreatic perfusion computed tomography (CT) imaging is increasingly used for neoplastic grading, predicting prognosis, and evaluating the response to therapy. To optimize the clinical pancreatic CT perfusion imaging methods, we evaluated 2 different CT scanning protocols concerning pancreas perfusion parameters. A retrospective study was conducted on 40 patients who underwent whole pancreas CT perfusion scanning in The First Affiliated Hospital of Zhengzhou University. Of these 40 patients, 20 patients in group A underwent continuous perfusion scanning, while 20 patients in group B underwent intermittent perfusion scanning. For group A, continuous axial scanning was performed 25 times, and the total scan time was 50 s. For group B, arterial phase helical perfusion scanning was performed 8 times, and then venous phase helical perfusion scanning was performed 15 times, with a total scan time of 64.6 to 70.0 s. A comprehensive list of perfusion parameters between different parts of the pancreas and the 2 groups were compared. The effective radiation dose for the 2 scanning methods was analyzed. The parameter of the mean slope of increase (MSI) at different pancreatic parts in group A differed (P=0.028). The pancreas head had the lowest value, and the tail had the highest (about a 20% difference). In group A compared to group B, the blood volume of the pancreatic head was smaller (15.256±2.925 vs. 16.953±3.602), the positive enhanced integral was smaller (0.307±0.050 vs. 0.344±0.060) and the permeability surface was larger (34.205±9. 612 vs. 24.377±8.413); the blood volume of the pancreatic neck was smaller (13.940±2.691 vs. 17.173±3.918), the positive enhanced integral was smaller (0.304±0.088 vs. 0.361±0.051) and the permeability surface was larger (34.898±11.592 vs. 25. 794±8.149); the blood volume of the pancreatic body was smaller (16.142±4.006 vs. 18.401±2.513), the positive enhanced integral was smaller (0.305±0.093 vs. 0.342±0.048) and the permeability surface was larger (28.861±10.448 vs. 22.158±6. 017); the blood volume of the pancreatic tail was smaller (16.446±3.709 vs. 17.374±3.781), the positive enhanced integral was smaller (0.304±0.057 vs. 0.350±0.073) and the permeability surface was larger (27.823±8.228 vs. 21.509±7.768) (P<0.05). The effective radiation dose in the intermittent scan mode was slightly lower at 16.657±2.259 mSv than in the continuous scan mode (17.973±3.698 mSv). Different CT scanning intervals had a significant influence on whole pancreas blood volume, permeability surface, and positive enhanced integral. These demonstrate the high sensitivity of intermittent perfusion scanning for identifying perfusion abnormalities. Therefore, for the diagnosis of pancreatic diseases, intermittent pancreatic CT perfusion may be more advantageous.

Hemodynamic Changes in Patients with Chronic Internal Carotid Artery Occlusion After Recanalization.

This study aimed to investigate the feasibility and clinical efficacy of endovascular recanalization in patients with chronic internal carotid artery occlusion (CICAO) and explore the application value of computed tomography perfusion (CTP) in endovascular recanalization. This non-randomized controlled study included 41 patients with CICAO. All patients received active medical treatment. In this study, patients with successful endovascular recanalization and those who refused endovascular recanalization were included in the recanalization and medication groups, respectively. Before and 90 days after treatment, cognitive function was evaluated using the Montreal Cognitive Function Assessment, and neurological function was evaluated using the National Institutes of Health Stroke Scale and modified Rankin scale. For patients with successful endovascular recanalization, brain CTP imaging was performed to evaluate hemodynamic changes in patients with CICAO before and three days after treatment. Overall, 41 symptomatic patients with CICAO were included, and 20 patients received endovascular recanalization therapy, with a success rate of 60% (12/20). The perioperative complication rate was 15% (3/20); there were no events such as hyperperfusion, distal embolism, vascular rupture, or cerebral hemorrhage, and no stroke-related or death-related events. Patients were divided into a medication group (n=21) and recanalization group (n=12). After 90 days of follow-up, patients in the recanalization group showed greater improvement in overall cognitive and neurological function. In addition, successful endovascular recanalization significantly improved cerebral blood perfusion on the occluded side of patients with CICAO. Successful recanalization can effectively improve the overall cognitive and neurological functions of patients in the short term. CTP can be used to quantitatively evaluate not only the cerebral hemodynamic changes after internal carotid artery occlusion but also the improvement of cerebral blood perfusion after successful endovascular recanalization, which provides a reliable method for postoperative follow-up.

Endovascular Thrombectomy Versus Best Medical Management Beyond 24 Hours From Last Known Well in Acute Ischemic Stroke Due to Large Vessel Occlusion

Background The safety and efficacy of endovascular thrombectomy (EVT) in patients with acute ischemic stroke due to large vessel occlusion presenting beyond 24 hours from last known well (LKW) remains undetermined. Methods In this single center study, we identified patients with large vessel occlusion who were eligible for EVT based on noncontrast computed tomography (CT)/CT angiography (without CT perfusion or magnetic resonance imaging) using an Alberta Stroke Program Early CT Score of ≥5, National Institutes of Health Stroke Scale of ≥6, and presenting beyond 24 hours from LKW, between January 2018 and March 2022. During the study period, EVT service limitations meant patients eligible for EVT presenting outside service hours, routinely received best medical management (BMM). Functional and safety outcomes were compared between patients receiving EVT or BMM following multivariable adjustment for age, baseline stroke severity, Alberta Stroke Program Early CT Score, time from LKW, IV thrombolysis, and clot location. Results Among 35 patients presenting beyond 24 hours from LKW and eligible for EVT, 19 (54%) were treated with EVT and 16 (46%) with BMM. Alberta Stroke Program Early CT Score were similar across both groups (EVT: 7 [6.75–8] versus BMM: 7 [6–8]), but not the baseline National Institutes of Health Stroke Scale (EVT: 17 [11–19.5] versus BMM: 20 [9.75–26]). No significant difference was observed between the EVT and BMM groups in the symptomatic intracranial hemorrhage (5.3% versus 0%; P =0.28) or mortality (26.3% versus 37.5%; P =0.42) rates, respectively. The modified Rankin scale at 90 days (adjusted common odds ratio [OR], 1.94; [95% CI 0.42–8.87]; P =0.39) and functional independence rate, although numerically higher in the EVT group compared with the BMM group (modified Rankin scale≤2; 36.9% versus 18.8%; adjusted OR, 4.34; [95% CI 0.34–54.83]; P =0.25), were not significantly different. 94.7% of patients treated with EVT achieved successful reperfusion (modified thrombolysis in cerebral infarction 2b–3). Conclusion In routine clinical practice, EVT beyond 24 hours from LKW appears safe and feasible, when performed in patients with acute ischemic stroke who were deemed eligible for EVT by noncontrast CT /CT angiography alone. A large collaborative randomized trial assessing the efficacy of EVT beyond 24 hours is warranted. Our findings provide a basis for the sample size estimate for an adequately powered trial.

CT Perfusion Imaging Guides Clinical Decision Making in a Case of Thalamic Stroke (P3-5.021)

<h3>Objective:</h3> NA <h3>Background:</h3> Perfusion neuroimaging has become crucial to acute stroke treatment due to its ability to identify areas of reduced perfusion and salvageable tissue. In select situations, current guidelines recommend the use of perfusion imaging to identify patients with a favorable profile for candidates for mechanical thrombectomy. The applicability of perfusion findings in other acute stroke scenarios is less established. <h3>Design/Methods:</h3> NA <h3>Results:</h3> A 77 year old female with hypertension and obesity presented with altered mental status to the emergency room as a pre-arrival stroke alert after being found unarousable by her partner in bed. Her last known well time was 2 hours prior to presentation. On arrival she had a blood pressure of 127/92 and was afebrile. Neurologic exam showed a decreased level of alertness. She did not respond to loud auditory stimuli. She grimaced to sternal rub and was able to briefly follow requests to give a thumbs up bilaterally. She produced no speech and withdrew all extremities from protopathic stimulation. Reflexes were 2+ and symmetric. Initial head computed tomography (CT) showed no abnormality. CT perfusion showed a perfusion deficit of 4mL in the posterior circulation. CT angiogram of the head and neck showed no abnormality. She was administered intravenous alteplase and admitted. MRI of the brain showed diffusion restriction in bilateral thalami. No embolic source was identified and she was placed on a long term cardiac monitor. One month following discharge she continued to have persistent aphasia, impaired cognition, and required 24-hour care. <h3>Conclusions:</h3> The clinical utility of perfusion neuroimaging extends beyond current clinical guidelines. Proficiency in study interpretation and correlation between patient presentation and neuroanatomical structures affected by perfusion deficits may allow additional stroke patients to receive treatment, particularly in atypical presentations of stroke such as altered mental status. <b>Disclosure:</b> Dr. Qureshi has nothing to disclose. Dr. Qaiser has nothing to disclose. Ms. Lozano has nothing to disclose. Dr. Farooq has nothing to disclose.

System-wide implementation of Computed Tomography Perfusion (CTP) Imaging for Acute Stroke: Impact on Quality, Safety and Outcomes (P7-5.009)

<h3>Objective:</h3> This study aims to assess the impact of CTP acquisition in regional hospitals on quality metrics, functional and safety outcomes in patients with LVO. <h3>Background:</h3> The utility of CTP imaging in spoke hospitals to determine eligibility for MT remains controversial. <h3>Design/Methods:</h3> Consecutive adult patients treated for LVO after initially presenting to regional spokes between Jan 2021 to Dec 2021 were included. CTP was added to acute stroke imaging protocol in April 2021. Demographics, NIHSS, quality metrics, imaging parameters, and functional outcomes were compared between patients who did vs. did not undergo CTP at a regional hospital. Core volume growth and rate (ml/min) was assessed for patients with CTP data both at the regional and at the CSC. <h3>Results:</h3> CTP studies were performed on 1083 in regional patients and LVO was confirmed in 29 (2.6%) patients. Of these, 14 were transferred to CSC without CTP at the regional and 15 were transferred with CTP at regional hospital. Age (p=0.44), NIHSS (p=0.08), door to thrombolysis (p=0.13), door-in-door-out (p=0.17) times, successful reperfusion (TICI IIb/III; p=0.83) and hemorrhagic transformation (ECASS III; p=0.49) did not differ significantly between the groups. Rates of mRS 0–2 were similar in both groups (p=0.85). In subgroup analysis of patients who underwent CTP both at the regional facility and CSC (n=15), median core volume grew significantly but slowly (0[0, 7] ml vs. 7 [0, 14] ml, p=0.022), at a median rate of 0 [0, 0.07] ml/min. No patients were excluded from thrombectomy due to core growth. <h3>Conclusions:</h3> Our study suggests that regional site perfusion imaging does not have a significant impact on process times, quality metrics and outcomes. Core volume grows during interfacility transfers without an impact on eligibility for MT. A larger study is needed to assess the role perfusion imaging in regional spokes. <b>Disclosure:</b> Miss Abarca has nothing to disclose. Dr. Potluri has nothing to disclose. Dr. Miller has nothing to disclose. Mrs. Stowe has nothing to disclose. Dr. Wideman has nothing to disclose. Dr. Tsai has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Cerenovus. Tricia Tubergen has received personal compensation in the range of $0-$499 for serving as a Consultant for Medtronic. Todd Mulderink has nothing to disclose. Dr. Min has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Abbott . Dr. Min has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Medtronic . Dr. Wees has nothing to disclose. Dr. Khan has nothing to disclose. Dr. Ahrar has nothing to disclose. Justin Singer has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Stryker. Justin Singer has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Medtronic. Justin Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Ceronovus. Justin Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Nico. The institution of Justin Singer has received research support from Stryker Grant. Paul Mazaris has nothing to disclose. John Oostema has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Life EMS. The institution of John Oostema has received research support from Spectrum Health. John Oostema has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant with MDHHS. The institution of Dr. Khan has received research support from NINDS. The institution of Dr. Khan has received research support from Genentech. The institution of Dr. Khan has received research support from Spectrum Health-MSU alliance. Dr. Khan has received research support from NIH.

Diagnostic accuracy of CT angiography and CT perfusion imaging for detecting distal medium vessel occlusions: Protocol for a systematic review and meta-analysis.

Distal medium vessel occlusions (DMVOs) represent 25-40% of all acute ischemic strokes (AIS). DMVO clinical syndromes are heterogenous, but as eloquent brain regions are frequently involved, they are often disabling. Since current intravenous fibrinolytic therapies may fail to recanalize up to two-thirds of DMVOs, endovascular treatment is progressively being considered in this setting. Nevertheless, the optimal imaging method for diagnosis remains to be defined. Stroke centers that use computed tomography as a routine stroke imaging approach rely on either isolated computed tomography angiography (CTA) or combined perfusion (CTP) studies. Despite a simplified non-CTP-dependent approach seeming reasonable for large vessel occlusion AIS diagnosis, CTP may still hold advantages for DMVOs workup. Therefore, this systematic review aims to compare the diagnostic performance of CTA and CTP in detecting DMVOs. We will perform a systematic search in PubMed, EMBASE, Web of Science Core Collection, and Cochrane Central Register of Controlled Trials. In addition, grey literature and ClinicalTrials.gov will be scanned. We will include any type of study that presents data on the diagnostic accuracy of CTA and/or CTP for detecting DMVOs. Two authors will independently review retrieved studies, and any discrepancies will be resolved by consensus or with a third reviewer. Reviewers will extract the data and assess the risk of bias in the selected studies. Data will be combined in a quantitative meta-analysis following the guidelines provided by the Cochrane Handbook for Systematic Reviews of Interventions. We will assess cumulative evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. This will be the first systematic review and meta-analysis that compares two different imaging approaches for detecting DMVOs. This study may help to define optimal acute ischemic stroke imaging work-up. PROSPERO registration: CRD42022344006.