Visualization of the Anterior Temporal Artery as a Predictor of Outcome in Middle Cerebral Artery Occlusion Patients Achieving Successful Recanalization After Transfer.

Introduction Anterior temporal artery (ATA) visualization on computed tomography angiography (CTA) has been previously associated with good outcomes in middle cerebral artery (MCA) occlusions, but not in the setting of patients who initially present to non-thrombectomy centers. Methods We retrospectively identified acute MCA (M1) occlusion patients who underwent mechanical thrombectomy after transfer from non-thrombectomy-capable centers. Neuroradiologists confirmed the MCA (M1) as the most proximal site of occlusion on CTA and assessed for visualization of the ATA. Thrombolysis in Cerebral Infarction (TICI) 2b or greater revascularization scores were confirmed by neurointerventionalists blinded to patient outcomes. Ninety-day modified Rankin scale (mRS) scores were obtained via a structured telephone questionnaire. Results We identified 102 M1 occlusion patients over a three-and-a-half-year period presenting to a non-thrombectomy-capable center who underwent transfer and mechanical thrombectomy. There were no significant differences in age, gender, race, comorbidities, or median National Institute of Health Stroke Scale (NIHSS) scores between the ATA visualized (n = 47) versus non-visualized (n = 55) cohort, and no significant differences in baseline Alberta Stroke Program Early Computed Tomography (ASPECT) scores, post-intervention TICI scores, or interval from last known well to revascularization. There was a strong trend in functional independent outcome (mRS ≤ 2) for patients with ATA visualization (63.8% vs. 45.5%, p = 0.064). Conclusion For patients presenting to non-thrombectomy centers without CT perfusion capability, ATA visualization should be further investigated as an outcome predictor, given its association with functional independence after successful recanalization. This article was previously presented as a meeting abstract at the 2021 International Stroke Conference on March 17-19, 2021.

Systematic review and meta-analysis of diagnostic test accuracy (DTA) studies: the role of cerebral perfusion imaging in prognosis evaluation of mild cognitive impairment.

BACKGROUND: The application value of cerebral perfusion imaging, such as fluorodeoxyglucose-positron-emission computed tomography (FDG-PET), single-photon emission computed tomography (SPECT), and structural magnetic resonance imaging (MRI), in the prognostic assessment of mild cognitive impairment (MCI) remains unclear. Thus, it was the focus of this meta-analysis, which aimed to provide a theoretical basis for early diagnosis of neurological diseases. METHODS: The Boolean logic retrieval method was used to retrieve related literature, with "cognitive disorder", "cerebral perfusion imaging", "cerebral imaging", "mild cognitive impairment", and "prognostic assessment" as search terms. The PubMed, Medline, CNKI (China National Knowledge Infrastructure), and other databases were searched from the date of establishment of the database to December 30, 2020 for literature on the prognostic assessment of MCI using FDG-PET, SPECT, and MRI imaging. Meta-analysis was performed using Review Manager software. RESULTS: A total of 16 references were identified, most of which had a low risk of bias (i.e. medium and high-quality). The meta-analysis results showed that the sensitivity and specificity of FDG-PET imaging was significantly higher than those of SPECT and MRI imaging, and the differences were statistically significant (P<0.05). The summary receiver operating characteristic (sROC) curves for the sensitivity and specificity of FDG-PET, SPECT, and MRI imaging did not present a "shoulder arm" distribution, and there was no threshold effect. DISCUSSION: Cerebral perfusion imaging has good prognostic value for patients with MCI, and FDG-PET imaging has better predictive ability of the prognosis for patients with MCI.

Angiography suite cone-beam CT perfusion for selection of thrombectomy patients: A pilot study.

BACKGROUND AND PURPOSE: The availability of cone-beam CT perfusion (CBCTP) in angiography suites may improve large-vessel occlusion (LVO) triage and reduce reperfusion times for patients presenting during extended time window. We aim to evaluate the perfusion maps correlation and agreement between multidetector CT perfusion (MDCTP) and CBCTP when obtained sequentially in patients undergoing endovascular therapy. METHODS: This is a prospective, pilot, single-arm interventional cohort study of consecutive patients with anterior circulation LVO. All patients underwent MDCTP and CBCTP prior to endovascular therapy, generating cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-maximum/time to peak contrast concentration maps. We compared the two imaging modalities using three different methods: (1) six regions of interest (ROIs) placed in the anterior circulation territory; (2) ROIs placed in all 10 Alberta Stroke Program Early CT Score regions; and (3) ROI drawn around the entire ischemic area. ROI ratios (unaffected/affected area) were compared for all sequences in each method. We used the intraclass correlation coefficient to calculate the correlation between the studies. Bland-Altman plots were also created to measure the degree of agreement. Finally, a sensitivity analysis was done comparing both modalities in patients with low infarct growth rate. RESULTS: Fourteen patients were included (median age 81 years [74-87], 50% males, median National Institutes of Health Stroke Scale 19 [14-22]). Median time between studies was 42 minutes (interquartile range 29-61). Independently of the method used, we found moderate to excellent correlation in CBF, CBV, and MTT between modalities. CBF correlation further improved in patients with low infarct growth. CONCLUSION: These results demonstrate promising accuracy of CBCTP in evaluating ischemic tissue in patients presenting with LVO ischemic stroke.

Arterial input function segmentation based on a contour geodesic model for tissue at risk identification in ischemic stroke.

PURPOSE: Perfusion parameters such as cerebral blood flow (CBF) and Tmax have been proven to be useful in the diagnosis and prognosis for ischemic stroke. Arterial input function (AIF) is required as an input to estimate perfusion parameters. This makes the AIF selection paradigm of clinical importance. METHODS: This study proposes a new technique to address the problem of AIF selection, based on a variational segmentation model that combines geometric constraint in a distance function. The modified model uses discrete total variation in the distance term and via minimizing energy locates the arterial regions. Matrix analysis is utilized to identify the AIF with maximum peak height within the segmented region. RESULTS: Group mean differences indicate that overall the AIF selected by the purposed method has better arterial features of higher peak position (16.7 and 26.1 a.u.) and fast attenuation (1.08 s and 0.9 s) as compared to the other state-of-the-art methods. Utilizing the selected AIF, mean CBF, and Tmax values were estimated higher than the traditional methods. Ischemic regions were precisely located through the perfusion maps. CONCLUSIONS: This AIF segmentation framework worked on perfusion images at levels superior to the current clinical state of the art. Consequently, the perfusion parameters derived from AIF selected by the purposed method were more accurate and reliable. The proposed method could potentially be considered as part of the calculation for perfusion imaging in general.

Apparent posterior cerebral artery territory perfusion asymmetry on arterial spin labeling MRI is a common non-pathologic finding in patients with a unilateral fetal posterior cerebral artery.

PURPOSE: To determine the frequency of apparent posterior cerebral artery (PCA) territory asymmetry seen on arterial spin labeling (ASL) imaging in patients with a unilateral fetal PCA, but without underlying clinical or imaging pathology to suggest true hypoperfusion. METHODS: A search of radiology reports from 1/2017 through 6/2020 was performed with the inclusion term "fetal PCA." Eighty patients were included with unilateral fetal PCA confirmed on MRA or CTA, with brain MRI including ASL imaging, and without conventional imaging abnormality or clinical symptoms referable to the PCA territories. Cases were evaluated by two independent readers for visually apparent PCA perfusion asymmetries. ASL imaging consisted of pseudocontinuous ASL with 1.5 s labeling duration and 2 s post-labeling delay adapted from white paper recommendations. RESULTS: Thirteen of 80 cases (16.2%) had apparent hypoperfusion in the PCA territory contralateral to the side of the fetal PCA. Agreement between readers was near perfect (97.5%, κ = 0.91). This finding was more common in patients who were older, scanned on a 3.0 T magnet, and who had non-visualization of the posterior communicating artery contralateral to the fetal PCA. CONCLUSION: Apparent PCA hypoperfusion on ASL is not uncommon in patients with a contralateral fetal PCA who have no clinical or conventional imaging findings to suggest true hypoperfusion. This phenomenon is likely due to differential blood velocities between the carotid and vertebral arteries that result in differential arterial transit times and labeling efficiency. It is important for radiologists to know that apparent hypoperfusion may arise from variant circle of Willis anatomy.

Limb-shaking TIA: a case of cerebral hypoperfusion in severe cerebrovascular disease in a young adult.

BACKGROUND: Limb-shaking transient ischaemic attacks (TIAs) are an under recognised presentation of severe cerebrovascular disease resulting from cerebral hypoperfusion. Patients present with jerking, transitory limb movements precipitated by change in position or exercise that are often confused with seizure. Cerebral perfusion imaging studies are an important tool available to aid diagnosis. CASE PRESENTATION: We present the case of a young female who developed limb-shaking TIA in the context of progressive severe intracranial atherosclerotic disease (ICAD). Previous cortical infarction raised suspicion for seizure as a cause of her symptoms. However, single photon emission CT (SPECT) with CT acetazolamide challenge identified severe left hemisphere cerebral hypoperfusion and a diagnosis of limb-shaking TIA was made. Symptoms improved with maximal medical management. CONCLUSIONS: This case highlights the importance of cerebral perfusion imaging for diagnostic confirmation as well as therapeutic options available to alleviate symptoms and reduce stroke risk in patients with limb-shaking TIA.

The application value of dual-layer detector spectral CT angiography in evaluation of brain perfusion in patients with acute ischemic stroke / 中华放射学杂志

Objective:To explore the clinical application value of the dual-layer detector spectral CTA in evaluation of brain perfusion impairment in patients with acute ischemic stroke.Methods:Clinical and imaging data of 35 patients with acute ischemic stroke in Weihai Central Hospital from March 2020 to October 2020 were reviewed retrospectively. All patients underwent head and neck spectral CTA examination and dynamic cerebral perfusion CT examination with dual-layer detector spectral CT. The iodine density map and effective atomic number map were reconstructed using CTA data, and the iodine density and effective atomic number, as well as the cerebral blood volume (CBV) and cerebral blood flow (CBF) values of the hypoperfusion area and the contralateral side were measured and compared; the areas of brain hypoperfusion regions were measured. Pearson′s correlation coefficient was used to analyze the correlation between iodine density values and CBV values, iodine density values and CBF values, effective atomic number values and CBV values, effective atomic number values and CBF values, as well as hypoperfusion area shown on CTA images and displayed on CTP-CBF map.Results:Of all the 35 patients, the iodine density value [(0.22±0.07) mg/ml], effective atomic number value (7.38±0.05), CBV value [(1.9±0.7) ml/100 g] and CBF value [(15.1±5.9) ml/(100 g·min)] of the hypoperfusion area were significantly lower than those of the healthy side [iodine density value (0.44±0.10) mg/ml, effective atomic number value (7.52±0.06), CBV value (3.4±0.7) ml/100 g, CBF value (57±27) ml/(100 g·min); t values were -14.7, -14.5, -11.2, -9.7, respectively, all P<0.001]. No significant difference was found between the hypoperfusion area shown on spectral CTA [(2 292±1 393) mm 2] and shown on CTP-CBF map [(2 290±1 359) mm 2] ( t=-0.076, P=0.944). There was a positive correlation between iodine density value and CBV (affected side: r=0.350, P=0.039, healthy side: r=0.551, P=0.001); a positive correlation was also found between effective atomic number value and CBV (affected side: r=0.488, P=0.003, healthy side: r=0.552, P=0.001); and there was a strong positive correlation between the hypoperfusion area on CTA and that on CTP-CBF ( r=0.993, P<0.001). Conclusion:Dual-layer detector spectral CTA can provide the “one-stop” assessement including head and neck vascular evaluation, as well as the hypoperfution area measument, which can be an alternative rapid method for evaluation of patients with acute ischemic stroke.

Diagnostic accuracy of flat-panel computed tomography in assessing cerebral perfusion in comparison with perfusion computed tomography and perfusion magnetic resonance: a systematic review.

PURPOSE: Flat-panel computed tomography (FP-CT) is increasingly available in angiographic rooms and hybrid OR's. Considering its easy access, cerebral imaging using FP-CT is an appealing modality for intra-procedural applications. The purpose of this systematic review is to assess the diagnostic accuracy of FP-CT compared with perfusion computed tomography (CTP) and perfusion magnetic resonance (MRP) in cerebral perfusion imaging. METHODS: We performed a systematic literature search in the Cochrane Library, MEDLINE, Embase, and Web of Science up to June 2019 for studies directly comparing FP-CT with either CTP or MRP in vivo. Methodological quality was assessed using the QUADAS-2 tool. Data on diagnostic accuracy was extracted and pooled if possible. RESULTS: We found 11 studies comparing FP-CT with CTP and 5 studies comparing FP-CT with MRP. Most articles were pilot or feasibility studies, focusing on scanning and contrast protocols. All patients studied showed signs of cerebrovascular disease. Half of the studies were animal trials. Quality assessment showed unclear to high risks of bias and low concerns regarding applicability. Five studies reported on diagnostic accuracy; FP-CT shows good sensitivity (range 0.84-1.00) and moderate specificity (range 0.63-0.88) in detecting cerebral blood volume (CBV) lesions. CONCLUSIONS: Even though FP-CT provides similar CBV values and reconstructed blood volume maps as CTP in cerebrovascular disease, additional studies are required in order to reliably compare its diagnostic accuracy with cerebral perfusion imaging.

Analysis of the significance of cerebral perfusion imaging combined with CT angiography in the diagnosis and treatment plan of patients with ischemic stroke / 中国医师进修杂志

investigate the significance of cerebral perfusion imaging combined with CT angiography (CTA) in the diagnosis and treatment plan of patients with ischemic stroke. Methods Total of 44 patients with acute cerebral infarction were enrolled in Taizhou First People′s Hospital from January 2018 to September 2018. Cerebral perfusion imaging and CTA examination were performed simultaneously within 12 h after the onset of the disease. The images of perfusion imaging were processed using an image workstation to measure the level of perfusion parameters in the ischemic region of the patient′s brain. The head and neck of the patient were measured by CTA. The angiography was performed, and the cerebral angiography results of all patients were as the gold standard. The clinical diagnosis and diagnostic efficacy of different examination methods in patients with ischemic stroke was observed and compared, and the differences in the parameters of perfusion imaging between different perfusion abnormal areas and normal control areas were compared. Results When patients′ cerebral angiography and single-photon emission computed tomography (SPECT) was as the gold standard for comparison, cerebral blood flow (CBF) and mean transit time (MTT) had the highest accuracy among all parameters of perfusion imaging. The accuracy rate of perfusion imaging +CTA was 93.2% , with a specificity of 100.0% and a sensitivity of 90.1%, which was significantly higher than that of the clinical efficacy of single diagnosis. Conclusions Perfusion imaging combined with CTA can provide important supplementary reference information for clinical diagnosis and treatment of patients with ischemic stroke.

Analysis of the significance of cerebral perfusion imaging combined with CT angiography in the diagnosis and treatment plan of patients with ischemic stroke / 中国医师进修杂志

Objective@#To investigate the significance of cerebral perfusion imaging combined with CT angiography (CTA) in the diagnosis and treatment plan of patients with ischemic stroke.@*Methods@#Total of 44 patients with acute cerebral infarction were enrolled in Taizhou First People′s Hospital from January 2018 to September 2018. Cerebral perfusion imaging and CTA examination were performed simultaneously within 12 h after the onset of the disease. The images of perfusion imaging were processed using an image workstation to measure the level of perfusion parameters in the ischemic region of the patient′s brain. The head and neck of the patient were measured by CTA. The angiography was performed, and the cerebral angiography results of all patients were as the gold standard. The clinical diagnosis and diagnostic efficacy of different examination methods in patients with ischemic stroke was observed and compared, and the differences in the parameters of perfusion imaging between different perfusion abnormal areas and normal control areas were compared.@*Results@#When patients′ cerebral angiography and single-photon emission computed tomography (SPECT) was as the gold standard for comparison, cerebral blood flow (CBF) and mean transit time (MTT) had the highest accuracy among all parameters of perfusion imaging. The accuracy rate of perfusion imaging+CTA was 93.2%, with a specificity of 100.0% and a sensitivity of 90.1%, which was significantly higher than that of the clinical efficacy of single diagnosis.@*Conclusions@#Perfusion imaging combined with CTA can provide important supplementary reference information for clinical diagnosis and treatment of patients with ischemic stroke.

Application of mechanical thrombectomy in the patients with wake-up stroke / 上海交通大学学报（医学版）

Wake-up stroke (WUS), which is characterized by the uncertain onset time and poor short-term outcome, accounts for 25% of stroke. Due to the above two points, how to choose the treatment methods remains to be researched. The mechanical thrombectomy is the first-line treatment of acute ischemic stroke (AIS). DAWN and DEFUSE-3 studies have recently demonstrated that the treatment window can be expanded to 24 hours, so the endovascular treatment may be effective and safe in some WUS patients according to the existence of "the mismatch of clinical score and imaging infart core" by CT perfusion imaging and other modern imaging methods. This article summarized the application of mechanical thrombectomy in WUS treatment in recent years.