Application of Perfusion Imaging in the Telehealth Setting for Acute Ischemic Stroke.

In the remote telehealth setting, computed tomography perfusion (CTP) provides important information in assessing the suitability of reperfusion therapy for patients with stroke syndromes. This review will discuss key concepts surrounding the use of CTP, including basic science, clinical applications, pitfalls, recent trials, and technical considerations. CTP can enhance decision­making for patients who are in the extended window from stroke onset, and this review will address key concepts relevant to its use.

Role of Intravoxel Incoherent Motion and Dynamic-Contrast-Enhanced Perfusion in Response Prediction of Patients with Colorectal Cancer after Neoadjuvant Chemotherapy.

BACKGROUND: Colorectal cancer (CRC) is a complex malignancy requiring multimodal treatment strategies, including neoadjuvant chemoradiation therapy (Neo-CRT), to improve patient outcomes. However, the response to Neo-CRT varies among individuals, which necessitates the development of reliable predictors of treatment response. The present study aimed to investigate the role of intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) perfusion in predicting treatment response in CRC patients after Neo-CRT. METHODS: This study was conducted on patients diagnosed with locally advanced CRC who received Neo-CRT. IVIM and DCE perfusion imaging were performed before and after CRT. Quantitative parameters, including perfusion fraction (f), diffusion coefficient (D), and transfer constant (Ktrans), were calculated from the imaging data. Treatment response was assessed based on the pathological response after surgery. Statistical data were analyzed in SPSS v. 26 using the t-test and the chi-square method. RESULTS: A total of 51 patients (female: male = 22:29, mean age = 58.14±3.49) participated in the study. Among all the patients, 15 (29.4%) cases had good responses, while 36 (70.58%) cases did not respond to treatment. All DCE parameters showed higher sensitivity and specificity than IVIM D*. Ve, Kep, and DCE Ktrans indicated significant predictive power for treatment response. Ktrans was the most accurate parameter for predicting response to treatment. Overall sensitivity and specificity of DCE were 88.8% [95% CI: 80-95.6], and 80 % [95% CI: 65-90], and those of IVIM were 65.5% and 81%, respectively. Sensitivity and specificity for DCE + IVIM were 79.5% and 93.5%, and those of DCE + IVIM + standard magnetic resonance imaging were 80.2% and 86%, respectively. CONCLUSION: IVIM and DCE perfusion imaging could serve as promising tools for predicting treatment response in CRC patients after Neo-CRT.

Insights into multilevel tissue-level collateral status using ColorViz maps from dual data sources in acute ischemic cerebrovascular diseases: A STARD-compliant retrospective study.

This study aims to explore the utility of ColorViz mapping from dual data sources for assessing arterial collateral circulation and predicting cerebral tissue-level collateral (TLC) in patients with acute ischemic cerebrovascular diseases. A retrospective study was conducted at a single center on a cohort of 79 patients diagnosed with acute ischemic cerebrovascular diseases between November 2021 and April 2022, who had undergone both multi-phase CT angiography (mCTA) and computed tomography perfusion (CTP). The quality of images and arterial collateral status depicted on ColorViz maps from dual data-sets (mCTA and CTP) were assessed using a "5-point scale" and a "10-point scale," respectively. The status of TLC was evaluated by analyzing multilevel hypoperfusion volume and the hypoperfusion intensity ratio (HIR). The Spearman correlation coefficient was employed to examine the association between arterial collateral status derived from dual data sources and TLC. Receiver operating characteristic curve analysis was used to determine the diagnostic efficacy in detecting large vessel occlusive acute ischemic stroke (LVO-AIS). The ColorViz maps derived from dual data sources facilitated comparable image quality, with over 95% of cases meeting diagnostic criteria, for the evaluation of arterial level collateral circulation. Patients with robust arterial collateral circulation, as determined by dual data sources, were more likely to exhibit favorable TLC status, as evidenced by reductions in hypoperfusion volume (Tmax > 4 seconds, Tmax > 6 seconds, Tmax > 8 seconds, and Tmax > 10 seconds, P < .05) and HIR (Tmax > 6 seconds/4 seconds, Tmax > 8 seconds/4 seconds, Tmax > 10 seconds/4 seconds, and Tmax > 8 seconds/6 seconds, P < .05). The sensitivity and specificity in detecting LVO-AIS was 60.00% and 97.73% for mCTA source maps, while 74.29% and 72.73% for CTP source maps (P > .05 based on De-Long test). In conclusion, this study indicates that ColorViz maps derived from both data sources are equally important in evaluating arterial collateral circulation and enhancing diagnostic efficiency in patients with LVO-AIS, as well as offering insights into the TLC status based on hypoperfusion volume and HIR.

Patient-specific arterial input function for accurate perfusion assessment in intraoperative fluorescence imaging.

Significance: The arterial input function (AIF) plays a crucial role in correcting the time-dependent concentration of the contrast agent within the arterial system, accounting for variations in agent injection parameters (speed, timing, etc.) across patients. Understanding the significance of the AIF can enhance the accuracy of tissue vascular perfusion assessment through indocyanine green-based dynamic contrast-enhanced fluorescence imaging (DCE-FI). Aim: We evaluate the impact of the AIF on perfusion assessment through DCE-FI. Approach: A total of 144 AIFs were acquired from 110 patients using a pulse dye densitometer. Simulation and patient intraoperative imaging were conducted to validate the significance of AIF for perfusion assessment based on kinetic parameters extracted from fluorescence images before and after AIF correction. The kinetic model accuracy was evaluated by assessing the variability of kinetic parameters using individual AIF versus population-based AIF. Results: Individual AIF can reduce the variability in kinetic parameters, and population-based AIF can potentially replace individual AIF for estimating wash-out rate ( k ep ), maximum intensity ( I max ), ingress slope with lower differences compared with those in estimating blood flow, volume transfer constant ( K trans ), and time to peak. Conclusions: Individual AIF can provide the most accurate perfusion assessment compared with assessment without AIF or based on population-based AIF correction.

Laser speckle contrast imaging of perfusion in oncological clinical applications: a literature review.

BACKGROUND: Laser speckle coherence imaging (LSCI) is an emerging imaging modality that enables noninvasive visualization and assessment of tissue perfusion and microcirculation. In this article, we evaluated LSCI in imaging perfusion in clinical oncology through a systematic review of the literature. METHODS: The inclusion criterion for the literature search in PubMed, Web of Science and Scopus electronic databases was the use of LSCI in clinical oncology, meaning that all animal, phantom, ex vivo, experimental, research and development, and purely methodological studies were excluded. RESULTS: Thirty-six articles met the inclusion criteria. The anatomic locations of the neoplasms in the selected articles were brain (5 articles), breasts (2 articles), endocrine glands (4 articles), skin (12 articles), and the gastrointestinal tract (13 articles). CONCLUSIONS: While LSCI is emerging as an appealing imaging modality, it is crucial for more clinical sites to initiate clinical trials. A lack of standardized protocols and interpretation guidelines are posing the most significant challenge.

Dynamic Contrast Ultrasound Diagnostics (CEUS) of Liver Lesions and Post-treatment Control with A New High-resolution Examination Technique (HiFR) and Perfusion.

BACKGROUND AND AIMS: To evaluate, if high frame rate (HiFR) contrast-enhanced ultrasound (CEUS) and external perfusion analysis (VueBox®)can give answers on liver tumour diagnostics. METHODS: A multifrequency probe (C1-6 /Resona R9) and 1-2.4 ml ultrasound contrast medium were used for CEUS up to 5-6 min. Independent analysis of DICOM-CINE files was performed, correlated to follow-up, computed tomography, magnetic resonance imaging, or histopathology. RESULTS: In 110 patients the difference between marginal peak enhancement (PE) of malignant and benign leasions was significant. In the peripheral area, the AUCs were lower in malignant lesions (144.8±139.3) than in benign lesions (123.6±119.8). The mean transit time (mTT) was shorter in malignant lesions in the center. In the liver parenchyma, however, the mTT was significantly longer in malignant lesions (141.6±107.9s) than in benign lesions (128.8±138.6 s). The rise time (RT) was significantly shorter central (66.5±30.9s) and peripheral (72.8±35.1s) in malignant lesions than in benign lesions (114.33±159.58s). The wash in rate (WiR) in benign lesions was 848.3±2,563.7 rU in the center. Wash-out rate (WoR) in the center, peripheral and in the liver parenchyma showed a significantly lower wash-out in the malignant lesions. CONCLUSIONS: HiFR CEUS with perfusion analysis enables the assessment of focal, diffuse and post-interventional liver changes.

Perfusion imaging metrics after acute traumatic spinal cord injury are associated with injury severity in rats and humans.

Traumatic spinal cord injury (tSCI) causes an immediate loss of neurological function, and the prediction of recovery is difficult in the acute phase. In this study, we used contrast-enhanced ultrasound imaging to quantify intraspinal vascular disruption acutely after tSCI. In a rodent thoracic tSCI model, contrast-enhanced ultrasound revealed a perfusion area deficit that was positively correlated with injury severity and negatively correlated with hindlimb locomotor function at 8 weeks after injury. The spinal perfusion index was calculated by normalizing the contrast inflow at the injury center to the contrast inflow in the injury periphery. The spinal perfusion index decreased with increasing injury severity and positively correlated with hindlimb locomotor function at 8 weeks after injury. The feasibility of intraoperative contrast-enhanced ultrasound imaging was further tested in a cohort of 27 patients with acute tSCI of varying severity and including both motor-complete and motor-incomplete tSCIs. Both the perfusion area deficit and spinal perfusion index were different between motor-complete and motor-incomplete patients. Moreover, the perfusion area deficit and spinal perfusion index correlated with the injury severity at intake and exhibited a correlation with extent of functional recovery at 6 months. Our data suggest that intraoperative contrast-enhanced, ultrasound-derived metrics are correlated with injury severity and chronic functional outcome after tSCI. Larger clinical studies are required to better assess the reliability of the proposed contrast-enhanced ultrasound biomarkers and their prognostic capacity.

Unmasking of Agenesis of Right Pulmonary Artery with Unilateral Absence of Perfusion on Lung Scintigraphy.

We present a rare finding on lung ventilation-perfusion (V/Q) scintigraphy for a woman with longstanding dyspnea. CT of the chest showed volume loss on the right side, which raised concern about possible bronchiolitis obliterans or Swyer-James-MacLeod syndrome; however, the right pulmonary artery could not be visualized. A subsequent V/Q scan showed absence of perfusion and decreased ventilation to the entire right lung, consistent with agenesis of the right pulmonary artery. The patient's clinical course and imaging features mimicked Swyer-James-MacLeod syndrome, which usually presents with a matched perfusion defect in a single lung or lobe on V/Q scanning. This case highlights the importance of a multimodality imaging approach to achieve a diagnosis.

Effects of intracranial artery stenosis of anterior circulation on cognition-A CT perfusion-based study.

BACKGROUND: Intracranial atherosclerotic stenosis (ICAS) is one of the most important independent risk factors for stroke that is closely related to the occurrence of cognitive impairment. The relationship between ICAS and vascular cognitive impairment (VCI) remains unclear. Cerebral hemodynamic changes are one of the main causes of cognitive impairment. Computed tomographic perfusion (CTP) imaging can quantitatively analyze cerebral blood perfusion and quantify cerebral hemodynamic changes. Previous research on the relationship between hypoperfusion induced by ICAS and cognitive impairment, as well as its underlying mechanisms, remains relatively insufficient. This study is dedicated to elucidating the characteristics and potential mechanisms of cognitive impairment in ICAS patients with abnormal perfusion, utilizing CTP imaging as our primary investigative tool. METHODS: This study recruited 82 patients who suffer from non-disabling ischemic stroke (IS group) and 28 healthy controls. All participants underwent comprehensive neuropsychological assessments both collectively and individually, in addition to CTP imaging. Within the patient group, we further categorized individuals into two subgroups: the ischemic penumbra group (IP, N = 28) and the benign oligemia group (BO, N = 54), based on CTP parameters-Tmax. The correlations between cognitive function and abnormal perfusion were explored. RESULTS: The cognitive function, including the overall cognitive, memory, attention, executive functions, and language, was significantly impaired in the IS group compared with that in the control group. Further, there are statistical differences in the stroop color-word test-dot (Stroop-D) and Montreal Cognitive Assessment (MoCA) sub-items (memory + language) between the BO and IP groups. In the BO group, the score of Stroop-D is lower, and the MoCA sub-items are higher than the IP group. There is no correlation between CTP parameters and cognitive function. CONCLUSION: Cognitive function is significantly impaired in patients with ICAS, which is related to cerebral perfusion. Executive, memory, and language function were better preserved in ICAS patients without IP. Hence, this study posits that managing hypoperfusion induced by ICAS may play a pivotal role in the development of VCI.

Turn-table micro-CT scanner for dynamic perfusion imaging in mice: design, implementation, and evaluation.

Objective.This study introduces a novel desktop micro-CT scanner designed for dynamic perfusion imaging in mice, aimed at enhancing preclinical imaging capabilities with high resolution and low radiation doses.Approach.The micro-CT system features a custom-built rotating table capable of both circular and helical scans, enabled by a small-bore slip ring for continuous rotation. Images were reconstructed with a temporal resolution of 3.125 s and an isotropic voxel size of 65µm, with potential for higher resolution scanning. The system's static performance was validated using standard quality assurance phantoms. Dynamic performance was assessed with a custom 3D-bioprinted tissue-mimetic phantom simulating single-compartment vascular flow. Flow measurements ranged from 1.51to 9 ml min-1, with perfusion metrics such as time-to-peak, mean transit time, and blood flow index calculated.In vivoexperiments involved mice with different genetic risk factors for Alzheimer's and cardiovascular diseases to showcase the system's capabilities for perfusion imaging.Main Results.The static performance validation confirmed that the system meets standard quality metrics, such as spatial resolution and uniformity. The dynamic evaluation with the 3D-bioprinted phantom demonstrated linearity in hemodynamic flow measurements and effective quantification of perfusion metrics.In vivoexperiments highlighted the system's potential to capture detailed perfusion maps of the brain, lungs, and kidneys. The observed differences in perfusion characteristics between genotypic mice illustrated the system's capability to detect physiological variations, though the small sample size precludes definitive conclusions.Significance.The turn-table micro-CT system represents a significant advancement in preclinical imaging, providing high-resolution, low-dose dynamic imaging for a range of biological and medical research applications. Future work will focus on improving temporal resolution, expanding spectral capabilities, and integrating deep learning techniques for enhanced image reconstruction and analysis.

Quantitative non-contrast perfusion MRI in the body using arterial spin labeling.

Arterial spin labeling (ASL) is a non-invasive magnetic resonance imaging (MRI) method that enables the assessment and the quantification of perfusion without the need for an exogenous contrast agent. ASL was originally developed in the early 1990s to measure cerebral blood flow. The utility of ASL has since then broadened to encompass various organ systems, offering insights into physiological and pathological states. In this review article, we present a synopsis of ASL for quantitative non-contrast perfusion MRI, as a contribution to the special issue titled "Quantitative MRI-how to make it work in the body?" The article begins with an introduction to ASL principles, followed by different labeling strategies, such as pulsed, continuous, pseudo-continuous, and velocity-selective approaches, and their role in perfusion quantification. We proceed to address the technical challenges associated with ASL in the body and outline some of the innovative approaches devised to surmount these issues. Subsequently, we summarize potential clinical applications, challenges, and state-of-the-art ASL methods to quantify perfusion in some of the highly perfused organs in the thorax (lungs), abdomen (kidneys, liver, pancreas), and pelvis (placenta) of the human body. The article concludes by discussing future directions for successful translation of quantitative ASL in body imaging.

Indocyanine green near-infrared fluorescence bowel perfusion assessment to prevent anastomotic leakage in minimally invasive colorectal surgery (AVOID): a multicentre, randomised, controlled, phase 3 trial.

BACKGROUND: Anastomotic leakage is a severe postoperative complication in colorectal surgery and compromised bowel perfusion is considered a major contributing factor. Conventional methods to assess bowel perfusion have a low predictive value for anastomotic leakage. We therefore aimed to evaluate the efficacy of real-time assessment with near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) in the prevention of anastomotic leakage. METHODS: This multicentre, randomised, controlled, phase 3 trial was done in eight hospitals in the Netherlands. We included adults (aged >18 years) who were scheduled for laparoscopic or robotic colorectal surgery (with planned primary anastomosis) for benign and malignant diseases. Preoperatively, patients were randomly assigned (1:1) to fluorescence-guided bowel anastomosis (FGBA) or conventional bowel anastomosis (CBA) by variable block randomisation (block sizes 4, 6, and 8) and stratified by site. The operating surgeon and investigators analysing the data were not masked to group assignment. Patients were unmasked after the surgical procedure or after study end. In the FGBA group, surgeons marked anastomosis levels per conventional perfusion assessment and then administered 5 mg of ICG by 2 mL intravenous bolus. They assessed bowel perfusion using NIR fluorescence imaging and adjusted (or kept) transection lines accordingly. Only conventional methods for bowel perfusion assessment were used in the CBA group. The primary outcome was the difference in the rate of clinically relevant anastomotic leakage (ie, requiring active therapeutic intervention but manageable without reoperation [grade B] or requiring reoperation [grade C], per the International Study Group of Rectal Cancer) between the FGBA group and the CBA group within 90 days post-surgery. The primary outcome and safety were assessed in the intention-to-treat population. This study was registered with ToetsingOnline.nl (NL7502) and ClinicalTrials.gov (NCT04712032) and is complete. FINDINGS: Between July 2, 2020, and Feb 21, 2023, 982 patients were enrolled, of whom 490 were assigned to FGBA and 492 were assigned to CBA. After excluding 51 patients, the intention-to-treat population comprised 931 (463 assigned FGBA and 468 assigned CBA). Patients had a median age of 68·0 years (IQR 59·0-75·0) and 485 (52%) were male and 446 (48%) were female. Ethnicity data were not available. The overall 90-day rate of clinically relevant anastomotic leakage was not significantly different between the FGBA group (32 [7%] of 463 patients) and the CBA group (42 [9%] of 468 patients; relative risk 0·77 [95% CI 0·50-1·20]; p=0·24). No adverse events related to ICG use were observed. 313 serious adverse events in 229 (25%) patients were at 90-day follow-up (159 serious adverse events in 113 [24%] patients in the FGBA group and 154 serious adverse events in 116 [25%] patients in the CBA group). 18 (2%) people died by 90 days (ten in the FGBA group and eight in the CBA group). INTERPRETATION: ICG NIR fluorescence imaging did not reduce 90-day anastomotic leakage rates in this trial across all types of colorectal surgeries. Further research should be done in subgroups, such as rectosigmoid resections, for which evidence suggests ICG NIR might be beneficial. FUNDING: Olympus Medical, Diagnostic Green, and Intuitive Foundation.

Advancing 7T perfusion imaging by pulsed arterial spin labeling: Using a parallel transmit coil for enhanced labeling robustness and temporal SNR.

Non-invasive perfusion imaging by Arterial spin labeling (ASL) can be advantageous at Ultra-high field (UHF) MRI, since the image SNR and the T1 relaxation time both increase with the static field. However, ASL implementation, especially at 7T, is not trivial. Especially for ASL, UHF MRI comes with many challenges, mainly due to B1+ inhomogeneities. This study aimed to investigate the effects of different transmit coil configurations on perfusion-weighted imaging at 7T using a flow-sensitive alternating inversion recovery (FAIR) technique with time-resolved frequency offset corrected inversion (TR-FOCI) pulses for labeling and background suppression. We conducted a performance comparison between a parallel transmit (pTx) system equipped with 32 receive (Rx) and 8 transmit (Tx) channels and a standard setup with 32Rx and 2Tx channels. Our findings demonstrate that the pTx system, characterized by a more homogeneous B1 transmit field, resulted in a significantly higher contrast-to-noise ratio, temporal signal-to-noise ratio, and lower coefficient of variance (CoV) than the standard 2Tx setup. Additionally, both setups demonstrated comparable capabilities for functional mapping of the hand region in the motor cortex, achieving reliable results within a short acquisition time of approximately 5 minutes.

Perfusion Abnormalities on 24-Hour Perfusion Imaging in Patients With Complete Endovascular Reperfusion.

BACKGROUND: Perfusion abnormalities in the infarct and salvaged penumbra have been proposed as a potential reason for poor clinical outcome (modified Rankin Scale score >2) despite complete angiographic reperfusion (Thrombolysis in Cerebral Infarction [TICI3]). In this study, we aimed to identify different microvascular perfusion patterns and their association with clinical outcomes among TICI3 patients. METHODS: University Hospital Bern's stroke registry of all patients between February 2015 and December 2021. Macrovascular reperfusion was graded using the TICI scale. Microvascular reperfusion status was evaluated within the infarct area on cerebral blood volume and cerebral blood flow perfusion maps obtained 24-hour postintervention. Primary outcome was functional independence (90-day modified Rankin Scale score 0-2) evaluated with the logistic regression analysis adjusted for age, sex, and 24-hour infarct volume from follow-up imaging. RESULTS: Based on microvascular perfusion findings, the entire cohort (N=248) was stratified into one of the 4 clusters: (1) normoperfusion (no perfusion abnormalities; n=143/248); (2) hyperperfusion (hyperperfusion on both cerebral blood volume and cerebral blood flow; n=54/248); (3) hypoperfusion (hypoperfusion on both cerebral blood volume and cerebral blood flow; n=14/248); and (4) mixed (discrepant findings, eg, cerebral blood volume hypoperfusion and cerebral blood flow hyperperfusion; n=37/248). Compared with the normoperfusion cluster, patients in the hypoperfusion cluster were less likely to achieve functional independence (adjusted odds ratio, 0.3 [95% CI, 0.1-0.9]), while patients in the hyperperfusion cluster tended to have better outcomes (adjusted odds ratio, 3.3 [95% CI, 1.3-8.8]). CONCLUSIONS: In around half of TICI3 patients, perfusion abnormalities on the microvascular level can be observed. Microvascular hypoperfusion, despite complete macrovascular reperfusion, is rare but may explain the poor clinical course among some TICI3 patients, while a detrimental effect of hyperperfusion after reperfusion could not be confirmed.

Relative Cerebral Blood Flow as an Indirect Imaging Surrogate in Patients With Anterior Circulation Large Vessel Occlusion and Association of Baseline Characteristics With Poor Collateral Status.

BACKGROUND: In acute ischemic stroke (AIS), collateral status (CS) is an important predictor of favorable outcomes in patients with AIS. Among quantitative cerebral perfusion parameters, relative cerebral blood flow (rCBF) is considered an accurate perfusion-based indicator of CS. This study investigated the relationship between admission laboratory values, baseline characteristics, and CS as assessed by rCBF in patients with AIS-large vessel occlusion. METHODS AND RESULTS: In this retrospective multicenter study, consecutive patients presenting with AIS secondary to anterior circulation large vessel occlusion who underwent pretreatment computed tomography perfusion were included. The computed tomography perfusion data processed by RAPID (IschemaView, Menlo Park, CA) generated the rCBF. Binary logistic regression models assessed the relationship between patients' baseline characteristics, admission laboratory values, and poor CS. The primary outcome measure was the presence of poor CS, which was defined as rCBF <38% at a lesion size ≥27 mL. Between January 2017 and September 2022, there were 221 consecutive patients with AIS-large vessel occlusion included in our study (mean age 67.0±15.8 years, 119 men [53.8%]). Logistic regression showed that male sex (odds ratio [OR], 2.98 [1.59-5.59]; P=0.001), chronic kidney disease (OR, 5.18 [2.44-11.0]; P<0.001), admission National Institutes of Health Stroke Scale score ≥12 (OR, 5.17 [2.36-11.36]; P<0.001), and systolic blood pressure <140 (OR, 2.00 [1.07-3.76]; P=0.030) were associated with poor CS. CONCLUSIONS: Higher stroke severity on admission with National Institutes of Health Stroke Scale score ≥12, systolic blood pressure <140, chronic kidney disease, and male sex are statistically significantly associated with poor CS in patients with AIS due to anterior circulation large vessel occlusion as defined by rCBF <38%.

Hypoperfusion Intensity Ratio as an Indirect Imaging Surrogate in Patients With Anterior Circulation Large-Vessel Occlusion and Association of Baseline Characteristics With Poor Collateral Status.

BACKGROUND: Collateral status (CS) plays a crucial role in infarct growth rate, risk of postthrombectomy hemorrhage, and overall clinical outcomes in patients with acute ischemic stroke (AIS) secondary to anterior circulation large-vessel occlusions (LVOs). Hypoperfusion intensity ratio has been previously validated as an indirect noninvasive pretreatment imaging biomarker of CS. In addition to imaging, derangements in admission laboratory findings can also influence outcomes in patients with AIS-LVO. Therefore, our study aims to assess the relationship between admission laboratory findings, baseline characteristics, and CS, as assessed by hypoperfusion intensity ratio in patients with AIS-LVO. METHODS AND RESULTS: In this retrospective study, consecutive patients presenting with AIS secondary to anterior circulation LVO who underwent pretreatment computed tomography perfusion were included. The computed tomography perfusion data processed by RAPID (Ischema View, Menlo Park, CA) generated the hypoperfusion intensity ratio. Binary logistic regression models were used to assess the relationship between patients' baseline characteristics, admission laboratory findings, and poor CS. A total of 221 consecutive patients with AIS-LVO between January 2017 and September 2022 were included in our study (mean±SD age, 67.0±15.8 years; 119 men [53.8%]). Multivariable logistic regression showed that patients with AIS caused by cardioembolic and cryptogenic causes (adjusted odds ratio [OR], 2.67; 95% CI, 1.20-5.97; P=0.016), those who presented with admission National Institutes of Health Stroke Scale score ≥12 (adjusted OR, 3.12; 95% CI, 1.61-6.04; P=0.001), and male patients (adjusted OR, 2.06; 95% CI, 1.13-3.77; P=0.018) were associated with poor CS. CONCLUSIONS: Stroke caused by cardioembolic or cryptogenic causes, admission National Institutes of Health Stroke Scale score of ≥12, and male sex were associated with poor CS, as defined by hypoperfusion intensity ratio in the patients with AIS-LVO.

Diffusion- and Perfusion-Weighted Imaging to Detect Neurological Deficits in Acute Focal Cerebral Ischemia in Rabbits.

PURPOSE: To investigate the relationship of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) parameters with dysfunction in acute focal cerebral ischemia (ACI) rabbits. METHODS: The model of ACI in the middle cerebral artery was made using 30 adult male New Zealand rabbits. The dysfunction severities of the ACI rabbits were assessed using Purdy's score. A paired-sample rank sum test was adopted to compare the abnormal signal zone (ASZ) volumes from T2 weighted imaging (T2WI), dynamic susceptibility contrast-enhanced (DSC) imaging, and DWI with a relative cerebral blood flow (rCBF) map; correlations were analyzed between the volume of each ASZ and Purdy's score by Spearman's rank correlation coefficient. The degree of necrotic and apoptotic cells was evaluated in the ASZ from DWI and DSC PWI-DWI mismatch (PDM) zone. Correlations were analyzed between the index of cellular damage and Purdy's score, the volume of ASZs by Spearman's rank correlation coefficient. RESULTS: The ASZ volumes from DSC-PWI and the rCBF maps were larger than those from DWI (p < 0.001 and p < 0.001, respectively); those from the rCBF map (Z = 0.959, p < 0.001) and DSC-PWI (Z = 0.970, p < 0.001) were positively correlated with DWI; a positive correlation was found between Purdy's score and the ASZ volumes from DSC-PWI (Z = 0.889, p < 0.001), DWI (Z = 0.921, p < 0.001), and rCBF (Z = 0.891, p < 0.001). A significant difference was observed between the ASZ from DWI and the PDM zone in terms of the degree of necrotic (p < 0.001) and apoptotic cells (p < 0.001). The degree of cellular damage in the ASZ of DWI and PDM zone had no relationship with Purdy's score and the volumes of ASZs. CONCLUSION: The ASZ volumes from DSC-PWI, rCBF, and particularly DWI reflected the level of dysfunction in rabbits with ACI.

Quantitative diagnosis of carotid blowout syndrome with CT perfusion: Carotid blowout syndrome CTP quantitative diagnosis.

BACKGROUND AND PURPOSE: Carotid blowout syndrome (CBS) is a potentially fatal disease. The CBS diagnosis mainly relies on subjective observations and the quantitative diagnotic method was not well established. This study aimed to diagnose CBS severity by computed tomography perfusion (CTP) parameters with different region-of-interest (ROI) models. MATERIALS AND METHOD: We prospectively recruited CBS patients between February 1, 2018 and July 31, 2023 in a tertiary medical center, and CTP was performed using the same 128-detector CT machine. Digital subtraction angiography (DSA) and elective endovascular intervention were performed within 3 days post-CTP for diagnosis confirmation and treatments. CBS severity was classified into ongoing (threatened + impending) or acute CBS based on DSA findings and clinical features. Pericarotid soft-tissue (PCST) CTP parameters, including blood flow (BF), blood volume (BV), mean transit time (MTT) and flow extraction product (FEP), were evaluated and correlated on DSA. We depicted models A, B and C for the small focal lesion in 1 cm of PCST, 1 cm around PCST and the whole PCST respectively. RESULTS: CTP images of 110 patients (77 ongoing (45 threatened + 32 impending); 33 acute) were analyzed. Pericarotid BV (1.8 ± 1.2vs.3.5 ± 2.0; p < 0.001) in Model A and BF in Model B (42.6 ± 11.0vs.50.9 ± 20.4; p = 0.031) were lower in acute-CBS than in ongoing-CBS patients. Subgroup analysis demonstrated lower BV in acute (1.8 ± 1.2) compared with threatened (3.7 ± 2.3; p < 0.001; p < 0.001) and impending (3.2 ± 1.6; p = 0.009) CBS patients in Model A. CONCLUSION: CBS severity can be quantitatively diagnosed by pericarotid soft-tissue CTP parameters. In Model A (small focus), BV was capable of differentiating acute CBS from other subtypes, demonstrating its potential role as a CBS imaging biomarker.

MRI-based ventilation and perfusion imaging to predict radiation-induced pneumonitis in lung tumor patients at a 0.35T MR-Linac.

BACKGROUND AND PURPOSE: Radiation-induced pneumonitis (RP), diagnosed 6-12 weeks after treatment, is a complication of lung tumor radiotherapy. So far, clinical and dosimetric parameters have not been reliable in predicting RP. We propose using non-contrast enhanced magnetic resonance imaging (MRI) based functional parameters acquired over the treatment course for patient stratification for improved follow-up. MATERIALS AND METHODS: 23 lung tumor patients received MR-guided hypofractionated stereotactic body radiation therapy at a 0.35T MR-Linac. Ventilation- and perfusion-maps were generated from 2D-cine MRI-scans acquired after the first and last treatment fraction (Fx) using non-uniform Fourier decomposition. The relative differences in ventilation and perfusion between last and first Fx in three regions (planning target volume (PTV), lung volume receiving more than 20Gy (V20) excluding PTV, whole tumor-bearing lung excluding PTV) and three dosimetric parameters (mean lung dose, V20, mean dose to the gross tumor volume) were investigated. Univariate receiver operating characteristic curve - area under the curve (ROC-AUC) analysis was performed (endpoint RP grade≥1) using 5000 bootstrapping samples. Differences between RP and non-RP patients were tested for statistical significance with the non-parametric Mann-Whitney U test (α=0.05). RESULTS: 14/23 patients developed RP of grade≥1 within 3 months. The dosimetric parameters showed no significant differences between RP and non-RP patients. In contrast, the functional parameters, especially the relative ventilation difference in the PTV, achieved a p-value<0.05 and an AUC value of 0.84. CONCLUSION: MRI-based functional parameters extracted from 2D-cine MRI-scans were found to be predictive of RP development in lung tumor patients.

Indocyanine green fluorescence perfusion testing in robot-assisted hepatic arterial infusion pump placement.

BACKGROUND: Hepatic arterial infusion pump (HAIP) treatment is a technique used to treat liver localized malignancy with intra-arterial chemotherapy. Methylene blue is generally administered to verify hepatic perfusion and exclude inadvertent extrahepatic perfusion. The use of indocyanine green dye (ICG) combined with near-infrared (NIR) fluorescence imaging during robot-assisted HAIP placement may be an attractive alternative by providing high contrast without blue discoloration of the operative field. METHODS: Data was collected retrospectively from 2 centers in the Netherlands. Intraoperative perfusion of the liver segments and extrahepatic perfusion were assessed using ICG/NIR as well as methylene blue on video imaging and correlated to postoperative 99 m-Tc perfusion scintigraphy. RESULTS: 13 patients underwent robot-assisted surgery for HAIP placement; median length of stay was 4 days, complications occurred in 4 patients. Hepatic perfusion showed identical patterns when ICG was compared with methylene blue. In 1 patient, additional extrahepatic perfusion was found using ICG, leading to further vessel ligation. Intraoperative ICG perfusion was concordant with 99 m-Tc perfusion scintigraphy. DISCUSSION: Liver and extrahepatic perfusion determined by ICG fluorescence imaging is concordant with blue dye perfusion and 99 m-Tc perfusion scintigraphy. Therefore, ICG fluorescence imaging is deemed a safe and reliable technique for perfusion testing during robot-assisted HAIP placement.