Cerebral Blood Flow Ratio Research Articles

Visualization of “subclinical consequence” after successful and uneventful surgical intervention for unruptured cerebral aneurysms

There are many studies on post-operative cognitive function after surgical clipping (SC) and endovascular coiling (EC) for unruptured cerebral aneurysms, but few reports focusing on possible subclinical damage. The aim of the present study was to detect the subclinical damage after surgical intervention. Patients with anterior circulation aneurysms who underwent either SC (SC group) or EC (EC group) were recruited. Imaging studies and evaluation of cognitive function were performed within 1 month preoperatively and at 6 months and 2 years postoperatively. The ipsilateral/contralateral cerebral blood flow (CBF) ratio (I/C ratio) calculated from values in four regions of interest (ROIs) placed on N-isopropyl-p-[123I] iodoamphetamine (123I-IMP)-single photon emission computed tomography (SPECT) was used to detect "subclinical consequence". "Subclinical consequence" was defined as post-operative CBF reduction without abnormality in other radiological examinations and cognitive tests. There were 14 patients in the SC group (mean age, 60.6±11.7 years) and 33 patients in the EC group (mean age, 67.5±7.2 years). All cognitive assessment results showed no significant reduction through the survey period. However, I/C ratios were restored by 2 years in the EC group not but in the SC group. I/C ratios at 6 months and 2 years were significantly lower in the SC group than the EC group (P<0.01). 123IMP-SPECT revealed a statistically significant reduction in ipsilateral CBF in patients who had an uneventful clinical course and no cognitive problems. The subclinical consequence could persist for at least 2 years following SC, and was less pronounced following EC.

Dynamic susceptibility contrast‑enhanced perfusion magnetic resonance imaging parameters for predicting MGMT promoter methylation and prognostic value in newly diagnosed patients with glioblastoma.

O6-methylguanine DNA methyltransferase (MGMT) promoter methylation is an important clinical biomarker of newly diagnosed glioblastoma. Previous radiological studies using dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) perfusion have aimed to predict MGMT methylation status non-invasively in gliomas with radiological characteristics. The possibility of predicting MGMT methylation status using DSC-MRI perfusion with a radiological approach remains controversial. The present study aimed to evaluate the usefulness of MRI perfusion parameters as non-invasive markers to predict MGMT methylation status and prognosis in newly diagnosed glioblastoma patients. Thus, 50 patients with histologically confirmed primary glioblastoma, IDH-wildtype who underwent tumor resection at Osaka University Hospital (Suita, Japan) between January 2017 and January 2023 were included in this study. The mean cerebral blood volume (CBV) ratio (rCBV) and cerebral blood flow (CBF) ratio (rCBF) for tumors with MGMT methylation (mean rCBV:2.09 and mean rCBF:3.08) were significantly higher compared with those for tumors without MGMT methylation (mean rCBV:1.33 and mean rCBF:1.85; P<0.05). While patients with MGMT methylation had longer progression-free survival (PFS) compared with those without MGMT methylation (P<0.05), there was no significant difference in OS with or without MGMT methylation (P=0.06). By contrast, there was no association between MRI perfusion parameters and OS or PFS in patients with glioblastoma. Furthermore, the association between CBV, CBF, MGMT promotor methylation status, OS, and PFS were explored. There was no significant prognostic difference between low vascularity tumors (rCBV <1.3 or rCBF <1.8) with or without MGMT methylation. On the other hand, high vascularity tumors (rCBF ≥1.8) with MGMT promotor methylation were associated to longer OS and PFS compared with those without. However, there was no association between MGMT methylation status and OS or PFS in patients with high rCBV (rCBV ≥1.3). The present study indicated that CBV and CBF could be used to predict the MGMT methylation status in glioblastomas. However, the prognostic value of tumor vascularity and MGMT methylation status may be limited.

Quantitative evaluation of CTP derived time-density alterations versus CTP for collateral status prediction with stroke

Background and ObjectivesCollateral status is a pivotal determinant of clinical outcomes in acute ischemic stroke (AIS); however, its evaluation can be challenging. We investigated the predictive value of CT perfusion (CTP) derived time and density alterations versus CTP for collateral status prediction in AIS. MethodsConsecutive patients with anterior circulation occlusion within 24 h were retrospectively included. Time-density curves of the CTP specified ischemic core, penumbra, and the corresponding contralateral unaffected brain were obtained. The collateral status was dichotomised into robust (4–5 scores) and poor (0–3 scores) using multiphase collateral scoring, as described by Menon et al.. Receiver operating characteristic curves and multivariable regression analysis were performed to assess the predictive ability of CTP-designated tissue time and density alterations, CTP for robust collaterals, and favourable outcomes (mRS score of 0–2 at 90 days). ResultsOne-hundred patients (median age, 68 years; interquartile range, 57–80 years; 61 men) were included. A smaller ischemic core, shorter peak time delay, lower peak density decrease, lower cerebral blood volume ratio, and cerebral blood flow ratio in the CTP specified ischemic core were significantly associated with robust collaterals (PFDR ≤ 0.004). The peak time delay demonstrated the highest diagnostic value (AUC, 0.74; P < 0.001) with 66.7 % sensitivity and 73.7 % specificity. Furthermore, the peak time delay of less than 8.5 s was an independent predictor of robust collaterals and favourable clinical outcomes. ConclusionsRobust collateral status was significantly associated with the peak time delay in the ischemic core. It is a promising image marker for predicting collateral status and functional outcomes in AIS.

Correlations between intravascular pressure gradients and cerebral blood flow in patients with symptomatic, medically refractory, anterior circulation artery stenosis: an exploratory study

BackgroundFractional flow reserve is widely used in coronary disease management, with a threshold of 0.80. However, similar thresholds are unclear in functional assessment of intracranial atherosclerotic stenosis (ICAS).ObjectiveTo investigate the...

Waveform Analysis of Superficial Temporal Artery-Middle Cerebral Artery Bypass Graft in Revascularization Surgery for Moyamoya Disease

Introduction: Postoperative hyperperfusion syndrome (PHS) is a well-known complication following superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for moyamoya disease (MMD). The early detection of postoperative radiological hyperperfusion (PRH), characterized by a transient increase in local cerebral blood flow (CBF), is crucial for the early diagnosis of PHS. This study aimed to investigate the effectiveness of waveform analysis for early PRH detection. Methods: We reviewed 52 consecutive patients who underwent STA-MCA bypass for MMD. Patients were divided into PRH and non-PRH groups based on the postoperative/preoperative CBF ratio. We collected the intraoperative bypass graft waveform and bypass flow data using a flowmeter. The pulsatile index (PI), an indicator of peripheral vascular resistance (PVR), was calculated from bypass flow data. Next, the newly proposed index of PVR, the ratio of the time from peak to 50% decay and to 100% decay (RT50), was calculated through waveform analysis. The values were then compared between the PRH and non-PRH groups. Results: Twenty-seven of the 52 patients met the inclusion criteria. Fourteen of these 27 patients showed PRH. The RT50, but not the PI, was significantly higher in the PRH group. Linear regression analysis revealed a significant correlation between the RT50 and PI. In the receiver operating characteristic for predicting PRH, the area under the curve of RT50 was 0.750, with a cutoff value of 0.255, a sensitivity of 0.928, and a specificity of 0.500. Conclusion: The RT50 obtained from waveform analysis is associated with PVR and can be useful for the early detection of PRH in patients with MMD.

Perfusion tomography in early follow-up of acute traumatic subdural hematoma: a case series.

Perfusion Computed Tomography (PCT) is an alternative tool to assess cerebral hemodynamics during trauma. As acute traumatic subdural hematomas (ASH) is a severe primary injury associated with poor outcomes, the aim of this study was to evaluate the cerebral hemodynamics in this context. Five adult patients with moderate and severe traumatic brain injury (TBI) and ASH were included. All individuals were indicated for surgical evacuation. Before and after surgery, PCT was performed and cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were evaluated. These parameters were associated with the outcome at 6 months post-trauma with the extended Glasgow Outcome Scale (GOSE). Mean age of population was 46 years (SD: 8.1). Mean post-resuscitation Glasgow coma scale (GCS) was 10 (SD: 3.4). Mean preoperative midline brain shift was 10.1mm (SD: 1.8). Preoperative CBF and MTT were 23.9ml/100g/min (SD: 6.1) and 7.3s (1.3) respectively. After surgery, CBF increase to 30.7ml/100g/min (SD: 5.1), and MTT decrease to 5.8s (SD:1.0), however, both changes don't achieve statistically significance (p = 0.06). Additionally, CBV increase after surgery, from 2.34 (SD: 0.67) to 2.63ml/100g (SD: 1.10), (p = 0.31). Spearman correlation test of postoperative and preoperative CBF ratio with outcome at 6 months was 0.94 (p = 0.054). One patient died with the highest preoperative MTT (9.97s) and CBV (4.51ml/100g). CBF seems to increase after surgery, especially when evaluated together with the MTT values. It is suggested that the improvement in postoperative brain hemodynamics correlates to favorable outcome.

Abstract TMP55: Arterial Spin Labeling Study Immediately After Thrombectomy: A Mechanism of Poor Prognosis Despite Recanalization

Introduction: In thrombectomy, the mechanism of poor prognosis despite complete recanalization is still unclear. Hyperperfusion may be a such poor prognostic mechanism. Residual microcirculatory dysfunction after restored large artery blood flow (no-reflow phenomenon) may also be a potential mechanism. MRI with arterial spin labeling (ASL) can easily assess cerebral perfusion. We here investigated the mechanism of poor prognosis despite recanalization by analyzing ASL images immediately after thrombus retrieval. Methods: This study included 41 consecutive cases (July 2019 to July 2023) with ICA or M1 embolic occlusions who underwent successful thrombectomy (mTICI3) and immediate post-operative ASL-MRI. Regional cerebral blood flow (CBF) on the ASL images were automatically quantified by means of 3DSRT software using 318 constant ROIs classified into 12 segments in each hemisphere. We evaluated the contralesional CBF ratio not only for the entire middle cerebral artery area and each of its segments, but also for each 3DSRT ROIs around the central sulcus (central arterial segment including 28 ROIs). These results of the post-operative ASL evaluation were compared between the favorable prognosis group (mRS 0-2 at 3 months) and the poor prognosis group (mRS 3-6). Results: There was no difference between the poor prognosis group (n=14) and the favorable prognosis group (n=27) in the comparison of the contralesional CBF ratio for the entire middle cerebral artery area or for each segment. However, the number of ROIs in the central segment decreased by 10% CBF or more and by 20% CBF or more compared to the contralesional side were significantly higher (both p&lt;0.01) in the poor prognosis group (19.1% against 11.8%, 3.1% against 0%, respectively). There was no difference in comparing the number of ROIs with increased CBF. Conclusions: This study showed that a high number of small-area (ROI) circulatory dysfunction (suggesting no-reflow phenomenon) was associated with a poor prognosis despite complete recanalization.

Clinical and imaging predictors for hemorrhagic transformation of acute ischemic stroke after endovascular thrombectomy.

Hemorrhagic transformation (HT) is a common complication of endovascular thrombectomy (EVT) in patients with acute ischemic stroke (AIS). Our study aims to investigate the clinical and imaging predictors of HT and symptomatic intracranial hemorrhage (sICH) in patients who underwent EVT. A retrospective analysis of 118 patients undergoing EVT for acute anterior circulation stroke was performed. Potential clinical and imaging predictors of all patients were collected and multivariate logistic regression was performed. The risk prediction system was constructed according to the multivariate logistic regression results. The incidence of HT and sICH after EVT were 46.6% and 15.3%, respectively. The multivariate logistic regression results showed that Alberta Stroke Program Early CT Score (ASPECTS) (p = .001, odds ratio [OR] = 0.367, 95% [confidence interval] CI, 0.201-0.670), collateral status (p<.001, OR = 0.117, 95% CI, 0.042-0.325), relative cerebral blood flow (CBF) ratio (p = .025, OR = 0.943, 95% CI, 0.895-0.993), and blood glucose on admission (p = .012, OR = 1.258, 95% CI, 1.053-1.504) were associated with HT. While for sICH, collateral circulation (p = .007, OR = 0.148, 95% CI, 0.037-0.589), ASPECTS (p = .033, OR = 0.510, 95% CI, 0.274-0.946), and blood glucose (p = .005, OR = 1.304, 95% CI, 1.082-1.573) were independent factors. The predictive model for HT after EVT was established, and the sensitivity and specificity of it were 90.9% and 79.4%, respectively, with the area under the curve of 90.0% (84.5%-95.4%). Collateral status, ASPECTS, relative CBF ratio, and blood glucose on admission were predictors for HT in AIS patients, while collateral status, ASPECTS, and blood glucose on admission were also predictors for sICH. In addition, the established predictive model showed good diagnostic value for prediction of HT after EVT.

Differential diagnostic value of 3.0T MR 3D-ASL technique for recurrence and pseudo-progression of high-grade glioma.

This study aimed to explore the value of 3.0T magnetic resonance three-dimensional arterial spin labeling imaging (3D-ASL) technology in the differential diagnosis of recurrence and pseudo-progression of high-grade gliomas. Fifty patients with high-grade glioma were selected as research objects. All 50 patients were examined by magnetic resonance imaging (MRI), and the lesions were found to be enlarged or abnormally enhanced. All the patients were examined using the 3.0T MR 3D-ASL technique. With targeted biopsy pathology as the gold standard, the diagnostic results of the 3.0T MR 3D-ASL technique were analyzed, and the cerebral blood flow (rCBFmax) ratio was compared between patients with recurrent glioma and patients with pseudo-progression [maximum blood flow value/contralateral mirror area (CBFmax/contralateral mirror area), CBFmax/contralateral white matter, CBFmax/contralateral gray matter]. Among 50 glioma patients, 31 (62.00%) were diagnosed with recurrence through pathological examination, and 19 (38.00%) were diagnosed with pseudo-progression. 30 patients with recurrence (60.00%) and 20 patients with pseudo-progression (40.00%) were diagnosed using 3.0T magnetic resonance 3D-ASL technology. The diagnostic accuracy of 3.0T magnetic resonance 3D-ASL technology was 96.77% (30/31) (p > 0.05). Using pathological results as the "gold standard", the relevant parameters of 3.0T magnetic resonance 3D-ASL technology under different pathological results were analyzed. The results showed that the CBFmax/contralateral mirror area, CBFmax/contralateral white matter, and CBFmax/contralateral gray matter ratios of advanced glioma recurrence patients were significantly higher than those of pseudo-progression (p < 0.05). The application of 3.0T MR 3D-ASL in high-grade glioma can effectively distinguish recurrence and pseudo-progression, with significant diagnostic value.

Blood-brain Barrier Permeability May Influence Vasopressor Effects in Anesthetized Patients With Brain Tumor: An Analysis of Magnetic Resonance Imaging Data

Objective: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. We hypothesized that vasopressors induce microcirculatory flow changes, characterized by increased capillary transit time heterogeneity (CTH) and decreased mean transit time (MTT), in brain regions exhibiting BBB leakage. Methods: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. Postvasopressor to prevasopressor ratios of CTH, MTT, relative transit time heterogeneity (RTH), cerebral blood flow (CBF), cerebral blood volume, and oxygen extraction fraction (OEF) were calculated in tumor, peritumoral, hippocampal, and contralateral grey matter regions. Comparisons were made between brain regions and vasopressors. Results: During phenylephrine infusion, ratios of CTH, RTH, and CBF were greater, and ratios of MTT and OEF were lower, in the tumor region with contrast leakage compared with corresponding contralateral grey matter ratios. During ephedrine infusion, ratios of CTH, MTT, RTH, CBF, and cerebral blood volume were higher in the tumor region with leakage compared with contralateral grey matter ratios. In addition, the ratio of CBF was higher in all regions, the ratio of RTH was lower in the leaking tumor region, and the ratio of OEF was lower in peritumoral, hippocampal, and grey matter regions with ephedrine compared with phenylephrine. Conclusions: Vasopressors can induce distinct microcirculatory flow alterations in regions with compromised brain tumor barrier or BBB. Ephedrine, a combined α and β-adrenergic agonist, appears to result in fewer flow alterations and less impact on tissue oxygenation compared with phenylephrine, a pure α-adrenergic agonist.

Perioperative cerebral blood flow measured by arterial spin labeling with different postlabeling delay in patients undergoing carotid endarterectomy: a comparison study with CT perfusion.

Arterial spin labeling (ASL) is a non-invasive technique for measuring cerebral perfusion. Its accuracy is affected by the arterial transit time. This study aimed to (1) evaluate the accuracy of ASL in measuring the cerebral perfusion of patients who underwent carotid endarterectomy (CEA) and (2) determine a better postlabeling delay (PLD) for pre- and postoperative perfusion imaging between 1.5 and 2.0 s. A total of 24 patients scheduled for CEA due to severe carotid stenosis were included in this study. All patients underwent ASL with two PLDs (1.5 and 2.0 s) and computed tomography perfusion (CTP) before and after surgery. Cerebral blood flow (CBF) values were measured on the registered CBF images of ASL and CTP. The correlation in measuring perioperative relative CBF (rCBF) and difference ratio of CBF (DRCBF) between ASL with PLD of 1.5 s (ASL1.5) or 2.0 s (ASL2.0) and CTP were also determined. There were no significant statistical differences in preoperative rCBF measurements between ASL1.5 and CTP (p = 0.17) and between ASL2.0 and CTP (p = 0.42). Similarly, no significant differences were found in rCBF between ASL1.5 and CTP (p = 0.59) and between ASL2.0 and CTP (p = 0.93) after CEA. The DRCBF measured by CTP was found to be marginally lower than that measured by ASL2.0_1.5 (p = 0.06) and significantly lower than that measured by ASL1.5_1.5 (p = 0.01), ASL2.0_2.0 (p = 0.03), and ASL1.5_2.0 (p = 0.007). There was a strong correlation in measuring perioperative rCBF and DRCBF between ASL and CTP (r = 0.67-0.85, p < 0.001). Using CTP as the reference standard, smaller bias can be achieved in measuring rCBF by ASL2.0 (-0.02) than ASL1.5 (-0.07) before CEA. In addition, the same bias (0.03) was obtained by ASL2.0 and ASL1.5 after CEA. The bias of ASL2.0_2.0 (0.31) and ASL2.0_1.5 (0.32) on DRCBF measurement was similar, and both were smaller than that of ASL1.5_1.5 (0.60) and ASL1.5_2.0 (0.60). Strong correlation can be found in assessing perioperative cerebral perfusion between ASL and CTP. During perioperative ASL imaging, the PLD of 2.0 s is better than 1.5 s for preoperative scan, and both 1.5 and 2.0 s are suitable for postoperative scan.

Pulsatility index of superficial temporal artery was associated with cerebral infarction after direct bypass surgery for moyamoya disease

ObjectiveDirect bypass surgery by superficial temporal artery (STA) – middle cerebral artery anastomosis is an established procedure for moyamoya disease (MMD). However, some patients may develop cerebral infarction (CI) due to the watershed shift phenomenon after the surgery. This study sought to investigate the correlation between the postoperative changes of STA flow as well as cerebral blood flow (CBF) and the incidence of CI after direct bypass surgery for MMD. MethodsWe conducted a retrospective study of 62 hemispheres in 50 subjects who underwent direct bypass surgery for MMD. All subjects underwent pre- and post-operative MR imaging, ultrasound evaluation of STA, and single-photon emission computed tomography. The presence of CI was correlated with preoperative CBF, the delta difference of each value of the STA between before and after the surgery, and the postoperative increase ratio of CBF. ResultsAll bypass procedures were patent, and CI was observed in 4 cases (6.4%). There was no significant association between the incidence of CI and both pre- and post-operative CBF. However, there was a significant difference in delta pulsatility index (PI) of the STA between cases with or without CI (-0.38±0.22 and -0.87±0.63, respectively, p=0.03). Whereas, other factors did not show any significant differences between those with or without CI. ConclusionsA relatively high postoperative PI of the STA was significantly associated with the incidence of CI after direct bypass surgery for MMD. A larger study is needed to confirm these findings.

Edaravone dexborneol alleviates cerebral ischemia-reperfusion injury through NF-κB/NLRP3 signal pathway.

Inflammatory injury following ischemia-reperfusion (I/R) severely limits the efficacy of stroke treatment. Edaravone dexborneol (C.EDA) has been shown to reduce inflammation following a cerebral hemorrhage. However, the precise anti-inflammatory mechanism of C.EDA is unknown. In this study, we investigated whether C.EDA provides neuroprotection after I/R in rats, as well as the potential mechanisms involved. A middle cerebral artery occlusion/reperfusion (I/R) model was created using Sprague-Dawley rats. The blood flow of the central cerebral artery was monitored by a laser speckle imaging system. The neurological score was used to assess behavioral improvement. Cerebral infarction volume was measured by TTC staining. And the integrity of the blood-brain barrier was detected by Evan's blue staining. The expression of the nuclear factor kappa-B (NF-κB)/ the NOD-like receptor protein (NLRP3) inflammasome signal pathway and microglia polarization were detected by immunofluorescence and Western blotting. The cerebral blood flow ratio indicates that the cerebral I/R model was successfully established. After reperfusion for 72 h, the improvement of neurological scores, infarct volume reduction, and integrity of the blood-brain barrier was observed in I/R rats with C.EDA treatment. Meanwhile, the immunofluorescence result showed that the expression of iNOS, NLRP3, and NF-κB protein was decreased and the level of Arg1 was increased. Western blot analysis showed that the expression of NF-κB/NLRP3 signal pathway-related protein was decreased. In conclusion, this study indicates that C.EDA alleviates I/R injury by blocking the activation of the NLRP3 inflammasome and regulating the polarization of M1/M2 microglia via the NF-κB signal pathway.

A Novel Staged Revascularization Strategy for Bilateral Severe Internal Carotid Artery Stenosis at High Risk for Hyperperfusion Syndrome

Since bilateral severe internal carotid artery stenosis often is associated with severely decreased cerebrovascular reactivity (CVR) due to poor collateral blood flow, revascularization carries a high risk for development of hyperperfusion syndrome. In this study, we report a new staged strategy to prevent postoperative hyperperfusion syndrome in such patients. Bilateral severe cervical internal carotid artery stenosis patients with decreased CVR to 10% or less on one side were prospectively enrolled in this study. We first performed carotid artery stenting on the side with the milder CVR decrease (lower-risk side), aiming to improve hemodynamics associated with the severe CVR decrease on the greater-risk side. Then, carotid endarterectomy or carotid artery stenting was performed on the contralateral side after an interval of 4-8 weeks. In all 3 cases enrolled in this study, CVR on the greater-risk side improved to 10% or more 1 month after the first treatment. The ratio of regional cerebral blood flow on the contralateral greater-risk side was 114% 1 day after the second treatment, and HPS did not develop in any of the cases. Our treatment strategy, in which revascularization on the lower-risk side precedes that on the greater-risk side, is effective for the prevention of HPS in bilateral ICA stenosis patients.

Clinical utility of intraoperative Arterial Spin Labeling for resection control in brain tumor surgery at 3 T.

Resection control in brain tumor surgery can be achieved in real time with intraoperative MRI (iMRI). Arterial spin labeling (ASL), a technique that measures cerebral blood flow (CBF) noninvasively without the use of intravenous contrast agents, can be performed intraoperatively providing morpho-physiological information. This study aimed to evaluate the feasibility, image quality and potential to depict residual tumor of a pseudo-continuous-ASL (PCASL) sequence at 3T. 17 patients with brain tumors, primary (16) or metastatic (1), undergoing resection surgery with iMRI-monitoring were prospectively recruited (9 men, age:56±16.6 years). A PCASL sequence with long labeling duration (3000ms) and postlabeling delay (2000ms) was added to the conventional protocol that consisted of pre- and post-contrast 3D-T1-weighted (T1w) images, optional 3D-FLAIR, and diffusion. Three observers independently assessed image quality (4-point scale) of PCASL-derived CBF maps. In those with diagnostic quality (scores 2-4) they evaluated the presence of residual tumor using the conventional sequences first, and the CBF maps afterwards (3-point scale). Inter-observer agreement for image quality and the presence of residual tumor was assessed using Fleiss-kappa statistics. Intraoperative CBF-ratio of the surgical margins (i.e., perilesional CBF values normalized to contralateral gray matter CBF) was compared to preoperative CBF-ratio within the tumor (Wilcoxon's test). Diagnostic ASL image quality was observed in 94.1% of patients (inter-observer Fleiss-κ=0.76). PCASL showed additional foci suspicious of high-grade residual component in three patients, and a hyperperfused area extending outside the enhancing component in one patient. Interobserver agreement was almost perfect in the evaluation of residual tumor with the conventional sequences (Fleiss-κ=0.92) and substantial for PCASL (Fleiss-κ=0.80). No significant differences were found between pre and intraoperative CBF-ratios (p=0.578) in patients with residual tumor (n=7). iMRI-PCASL perfusion is feasible at 3T and is useful for the intraoperative assessment of residual tumor, providing in some cases additional information to the conventional sequences.

Predicting a Favorable (mRS 0–2) or Unfavorable (mRS 3–6) Stroke Outcome by Arterial Spin Labeling and Amide Proton Transfer Imaging in Post-Thrombolysis Stroke Patients

(1) Background: The objective of this study was to determine whether arterial spin labeling (ASL), amide proton transfer (APT), or their combination could distinguish between patients with a low and high modified Rankin Scale (mRS) and forecast the effectiveness of the therapy; (2) Methods: Fifty-eight patients with subacute phase ischemic stroke were included in this study. Based on cerebral blood flow (CBF) and asymmetry magnetic transfer ratio (MTRasym) images, histogram analysis was performed on the ischemic area to acquire imaging biomarkers, and the contralateral area was used as a control. Imaging biomarkers were compared between the low (mRS 0-2) and high (mRS 3-6) mRS score groups using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of the potential biomarkers in differentiating between the two groups; (3) Results: The rAPT 50th had an area under the ROC curve (AUC) of 0.728, with a sensitivity of 91.67% and a specificity of 61.76% for differentiating between patients with low and high mRS scores. Moreover, the AUC, sensitivity, and specificity of the rASL max were 0.926, 100%, and 82.4%, respectively. Combining the parameters with logistic regression could further improve the performance in predicting prognosis, leading to an AUC of 0.968, a sensitivity of 100%, and a specificity of 91.2%; (4) Conclusions: The combination of APT and ASL may be a potential imaging biomarker to reflect the effectiveness of thrombolytic therapy for stroke patients, assisting in guiding treatment approaches and identifying high-risk patients such as those with severe disability, paralysis, and cognitive impairment.

Evaluation of collateral status and outcome in patients with middle cerebral artery stenosis in late time window by CT perfusion imaging.

ObjectivesCollateral status (CS) is a crucial determinant of outcome in patients with ischemic stroke. We aimed to test whether the cerebral blood volume (CBV) and cerebral blood flow (CBF) based on computed tomography perfusion (CTP) measurements can quantitatively evaluate CS and explore the predictive ability of CTP parameters in determining clinical outcomes in patients with MCA severe stenosis or occlusion presenting beyond 24 h.Materials and methodsIn this retrospective study, data obtained from September 2018 to March 2022 in consecutive stroke patients caused by isolated middle cerebral artery severe stenosis or occlusion were reviewed within 24–72 h after onset. Correlation between the collateral score systems assessed with CT angiography (CTA) and CTP parameters was calculated using the Spearman correlation. The optimal threshold of the CBV ratio for predicting a good outcome was determined using receiver operating characteristic curve (ROC) analysis.ResultsA total of 69 patients met inclusion criteria. Both the CBV ratio and the CBF ratio had significant correlation with collateral score systems assessed with CTA [CBV ratio and Tan score: rs = 0.702, P < 0.0001; CBV ratio and regional leptomeningeal collateral (rLMC) score: rs = 0.705, P < 0.0001; CBV ratio and Miteff score: rs = 0.625, P < 0.0001. CBF ratio and Tan score: rs= 0.671, P < 0.0001; CBF ratio and rLMC score: rs = 0.715, P < 0.0001; CBF ratio and Miteff score: rs = 0.535, P < 0.0001]. ROC analysis revealed the CBV ratio performed better than the qualitative collateral assessments and the CBF ratio in the prediction of a favorable 90-day modified Rankin scale score. The CBV ratio was a useful parameter that predicted a good functional outcome [area under the curve (AUC), 0.922; 95% CI, 0.862 ± 0.982].ConclusionsIn late time window stroke patients, the CBV and CBF ratio on CTP may be valuable parameters for quantitatively revealing the collateral status after stroke. In addition, the CBV ratio was the predictor of clinical outcomes in patients with MCA severe stenosis or occlusion.

The longitudinal evolution of cerebral blood flow in children with tuberous sclerosis assessed by arterial spin labeling magnetic resonance imaging may be related to cognitive performance.

To study longitudinal changes in tuber and whole-brain perfusion in children with tuberous sclerosis complex (TSC) using arterial spin labeling (ASL) perfusion MRI and correlate them with pathological EEG slow wave activity and neurodevelopmental outcomes. Retrospective longitudinal cohort study of 13 children with TSC, 3 to 6 serial ASL-MRI scans between 2 months and 7 years of age (53 scans in total), and an EEG examination performed within 2 months of the last MRI. Tuber cerebral blood flow (CBF) values were calculated in tuber segmentation masks, and tuber:cortical CBF ratios were used to study tuber perfusion. Logistic regression analysis was performed to identify which initial tuber characteristics (CBF value, volume, location) in the first MRI predicted tubers subsequently associated with EEG slow waves. Whole-brain and lobar CBF values were extracted for all patient scans and age-matched controls. CBF ratios were compared in patients and controls to study longitudinal changes in whole-brain CBF. Perfusion was reduced in tubers associated with EEG slow waves compared with other tubers. Low tuber CBF values around 6 months of age and large tuber volumes were predictive of tubers subsequently associated with EEG slow waves. Patients with severe developmental delay had more severe whole-brain hypoperfusion than those with no/mild delay, which became apparent after 2 years of age and were not associated with a higher tuber load. Dynamic changes in tuber and brain perfusion occur over time. Perfusion is significantly reduced in tubers associated with EEG slow waves. Whole-brain perfusion is significantly reduced in patients with severe delay. • Tubers associated with EEG slow wave activity were significantly more hypoperfused than other tubers, especially after 1 year of age. • Larger and more hypoperfused tubers at 6 months of age were more likely to subsequently be associated with pathological EEG slow wave activity. • Patients with severe developmental delay had more extensive and severe global hypoperfusion than those without developmental delay.

A Bayesian estimation method for cerebral blood flow measurement by area-detector CT perfusion imaging.

Bayesian estimation with advanced noise reduction (BEANR) in CT perfusion (CTP) could deliver more reliable cerebral blood flow (CBF) measurements than the commonly used reformulated singular value decomposition (rSVD). We compared the efficacy of CBF measurement by CTP using BEANR and rSVD, evaluating both relative to N-isopropyl-p-[(123) I]- iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT) as a reference standard, in patients with cerebrovascular disease. Thirty-one patients with suspected cerebrovascular disease underwent both CTP on a 320 detector-row CT system and SPECT. We applied rSVD and BEANR in the ischemic and contralateral regions to create CBF maps and calculate CBF ratios from the ischemic side to the healthy contralateral side (CBF index). The analysis involved comparing the CBF index between CTP methods and SPECT using Pearson's correlation and limits of agreement determined with Bland-Altman analyses, before comparing the mean difference in the CBF index between each CTP method and SPECT using the Wilcoxon matched pairs signed-rank test. The CBF indices of BEANR and 123I-IMP SPECT were significantly and positively correlated (r = 0.55, p < 0.0001), but there was no significant correlation between the rSVD method and SPECT (r = 0.15, p > 0.05). BEANR produced smaller limits of agreement for CBF than rSVD. The mean difference in the CBF index between BEANR and SPECT differed significantly from that between rSVD and SPECT (p < 0.001). BEANR has a better potential utility for CBF measurement in CTP than rSVD compared to SPECT in patients with cerebrovascular disease.

Neuronal Alterations in Secondary Thalamic Degeneration Due to Cerebral Infarction: A 11C-Flumazenil Positron Emission Tomography Study.

Background:Studies using animal experiments have shown secondary neuronal degeneration in the thalamus after cerebral infarction. Neuroimaging studies in humans have revealed changes in imaging parameters in the thalamus, remote to the infarction. However, few studies have directly demonstrated neuronal changes in the thalamus in vivo. The purpose of this study was to determine whether secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease.Methods:We retrospectively analyzed the data of 140 patients with unilateral cerebral infarction ipsilateral to internal carotid artery or middle cerebral artery disease. All patients had quantitative measurements of 11C-flumazenil binding potential (FMZ-BP), cerebral blood flow, and cerebral metabolic rate of oxygen using positron emission tomography in the chronic stage. Region of interest analysis was performed using NeuroFlexer—an automated region of interest analysis software using NEUROSTAT.Results:In the thalamus ipsilateral to the infarcts, the values of FMZ-BP, cerebral blood flow, and cerebral metabolic rate of oxygen were significantly lower than those in the contralateral thalamus. Significant correlations were found between the ipsilateral-to-contralateral ratio of FMZ-BP and the ipsilateral-to-contralateral ratio of cerebral blood flow or cerebral metabolic rate of oxygen in the thalamus. Patients with corona radiata infarcts and striatocapsular infarcts had significantly decreased ipsilateral-to-contralateral FMZ-BP ratio in the thalamus compared with those without. The ipsilateral-to-contralateral ratio of FMZ-BP in the thalamus was significantly correlated with the ipsilateral-to-contralateral cerebral metabolic rate of oxygen ratio in the frontal cortex and showed a significant negative correlation with the number of perseverative errors on the Wisconsin Card Sorting Test.Conclusions:Secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease, which may be associated with frontal lobe dysfunction.