Clot characteristics on computed tomography and response to thrombolysis in acute middle cerebral artery stroke

Basilar Dolichoarteriopathy and Early Clinical Deterioration in Acute Isolated Pontine Infarction

OBJECTIVES

Early clinical worsening (ECW) in acute isolated pontine infarcts (AIPI) is frequent, associated with poor prognosis, and its predictors have not been adequately clarified. A possible role of dolichoectatic basilar artery (BA) anatomy in ECW in patients with AIPI is herein studied.

METHODS

In 146 AIPI patients, infarcts were grouped into tegmental, lateral, anterolateral, anteromedial horizontally; and low, mid, mid-up, and upper pontine vertically. BA dolichoectasia was categorized according to Smoker criteria. An additional criteria of BA laterality angle was described. The length between the infarct long-axis and BA cross-sectional center was measured, and named as "branch length (BL)." ECW was defined as any increase in NIHSS.

RESULTS

ECW was seen in 22 (15%) patients. Univariate analysis documented a higher female ratio (22% vs. 10%, P =0.007), higher atrial fibrillation (18% vs. 7%, P =0.067), more common anteromedial infarct location (77% vs. 49%, P =0.025), and Smoker category-3 BA height (32% vs. 10%, P =0.043) in these patients. In anteromedial infarcts, BL was longer (8.3 vs. 6.1 mm, P =0.052), and reaching to significance in those located at mid-up/upper pontine level (1.22 vs. 0.62 mm, P =0.006). BL >4.4 mm showed an acceptable discriminatory capacity for ECW with an AUC of ROC: 0.615 (95% CI: 0.511-0.712). A regression model indicated female sex (β±SE=1.129±0.551, P =0.040), BL (per 4.4 mm, β±SE=1.236±0.614, P =0.044), and BA height-category-3 (β±SE=1.711±0.645, P =0.008) as independent predictors for ECW.

CONCLUSIONS

Some features of basilar dolichoarteriopathy, such as the extreme location of the height of the BA tip and the length of the involved perforator in the prepontine cistern, may be predictors of early clinical worsening in acute isolated pontine infarcts.

Pectoralis major muscle index as an opportunistic predictor of mortality in acute stroke patients treated with intravenous thrombolysis

BACKGROUND

Premorbid sarcopenia in acute stroke indicates poor prognosis. Since formal sarcopenia tests cannot be performed, the muscle features imaged in diagnostic studies are opportunistically used as surrogates for sarcopenia in the acute period.

METHODS

In 110 consecutive acute ischemic anterior circulation stroke patients treated with intravenous tissue plasminogen activator alone (mean age: 73±13 years, 55% women), the cross-sectional area (CSA) and attenuation of pectoralis major and minor muscles and mediastinal adipose tissue were measured at admission computed tomography (CT) angiography source images.

RESULTS

Pectoralis major and minor muscle CSA (mm2) and indices (CSA/height(m)2) were significantly higher in patients with 3-month modified Rankin's scores of 0-1 (excellent outcome, 41%), 0-2 (good outcome, 54%), and in surviving patients (87%). In regression models adjusted for age and NIHSS, pectoralis major muscle CSA (partial r: -0.281, p = 0.027) and pectoralis major index (partial r: -0.332, p = 0.008) were independent predictors of mortality. The discriminatory value of the pectoralis major index for mortality was good (ROC-AUC 0.794, 95%CI: 0.676-0.885). The optimal threshold for survival of pectoralis major index was > 3316 mm2/m2 with 0.607 Youden J index. No difference was found in muscle CT attenuation values, mediastinal adipose tissue area and radiodensity in deceased patients.

CONCLUSIONS

Our retrospective analysis documents that the pectoralis major index, a readily available CT anthropometry surrogate for sarcopenia, is an independent predictor of survival in patients with acute ischemic stroke undergoing systemic thrombolysis. It may suggest that the pectoralis major index could be included in the prognostic toolkit of acute ischemic stroke.

Dual-Energy CT-Based Thrombus Radiomics Can Predict Functional Outcome of Intravenous Thrombolysis in Acute Ischemic Stroke

To explore the predictive value of dual-energy CT-based thrombus radiomics for the functional outcome of intravenous thrombolysis in patients with acute ischemic stroke (AIS). One hundred four AIS patients who received intravenous thrombolysis were enrolled and classified into favorable and unfavorable outcome based on their modified Rankin Scale (mRS) scores at 90 days. All patients underwent a one-stop-shop CT scan upon admission, including NCCT, dual-energy CTA, and CTP. The thrombus radiological and radiomics models were developed using NCCT, CTA, and iodine overlay map (IOM) images. The clinical model was developed using clinical information and other radiological data. The best-performing radiomics model was selected for the further development of a clinical-radiomics nomogram. The performance of these models was evaluated using receiver operating characteristic (ROC) curves, clinical decision curves, calibration curves, and DeLong's test. The AUCs of the modelThrombus built using the thrombus characteristics were lower than those of most radiomics models (training, 0.77; test, 0.75). The AUCs of the modelIOM were higher than those of modelCTA (training, 0.84 vs. 0.71; test, 0.78 vs. 0.66) and were comparable to modelNCCT (training, 0.84 vs. 0.82; test, 0.78 vs. 0.78). The modelNCCT+IOM demonstrated improved predictive performance compared to either single-sequence model alone (training, 0.92; test, 0.83). Systolic blood pressure and baseline NIHSS score were independent predictors of favorable outcome. Among all models, the nomogram has the highest predictive value (training, 0.96; test, 0.91). The thrombus radiomics model based on dual-energy CT can effectively predict functional outcome of intravenous thrombolysis in patients with AIS. The addition of clinical data to the model can improve predictive performance.

Cerebral arterial collateral status, but not venous outflow profiles, modifies the effect of intravenous tissue plasminogen activator in acute ischemic stroke

BACKGROUND

The role of arterial collateral and venous outflow status on the response to intravenous tissue plasminogen activator (IV-tPA) has not been sufficiently clarified in acute major cerebral occlusions.

PATIENTS AND METHODS

A total of 130 patients (mean age: 71 years; 73 females) with acute middle cerebral artery M1/M2 segment or terminal internal carotid artery occlusion treated solely with IV-tPA were analyzed. Regional leptomeningeal score (rLMC) was used for cerebral arterial collateral scoring, and the cortical vein opacification score (COVES) and modified Prognostic Evaluation based on Cortical vein score difference In Stroke (PRECISE) superficial and deep scores were used for venous outflow profile. Exploratory logistic models for response to IV-tPA [positive response: National Institutes of Health Stroke Scale (NIHSS) decrease 4 (or decrease to 0) at 24 h; dramatic response: NIHSS decrease ≥8 (or decrease to 0 or 1)], functional outcome (modified Rankin's score 0-1 as "excellent" and 0-2 "good") and tPA-associated hemorrhagic transformation were constructed.

RESULTS

IV-tPA efficacy was positive in 47% and dramatic in 32%. Dramatic response was linked to better arterial collateral status (exp[B] =1.115 [95% confidence interval (CI), 1.016-1.223]). Excellent outcome was noted in 26% and good in 45%. One-point increase in rLMC score independently increased good prognosis (exp[B] =1.209 [1.034-1.412]). Patients with good prognosis had higher (by 0.5 points) modified PRECISE deep score (P = 0.047) and less frequent nonsufficient modified PRECISE deep score (0-2) (P = 0.017) in univariate analyses. However, these associations failed to survive in multiple regression. Any type tPA-associated cerebral hemorrhagic transformation was observed in 23% and parenchymal hemorrhage type 2 in 5.4%. While rLMC score showed a borderline strength correlation to hemorrhage (exp[B] =0.899 [95% CI, 0.808-1.001]), outflow scores not.

CONCLUSION

While arterial collateral status modifies the effect of tPA in acute anterior circulation major artery occlusions, venous outflow capacity is not so critical.

Carotid Artery Perivascular Adipose Tissue Density and Response to Intravenous Tissue Plasminogen Activator in Acute Ischemic Stroke

The importance of Carotid Artery Perivascular Adipose Tissue Density (CAPATd), a parameter that can be readily evaluated on emergency computed tomographic angiography (CTA), in acute stroke has not been adequately clarified. We created exploratory logistic regression models to detect the interaction between the effect of CAPATd and intravenous (IV) tissue plasminogen activator (tPA) in 174 patients (mean age 71 ± 14 years, 94 women) with acute ischemic stroke treated with IV-tPA alone. The CAPATd-average mean (-60.6 ± 18.7 vs -89.8 ± 25.3 Hounsfield units (HU), P = .002) and CAPATd-maximum (14.8 ± 68.9 vs -20.5 ± 39.8 HU, P = .020) values were higher on the ipsilateral side of carotid artery stenosis >60%. CAPATd-maximum ipsilateral emerged as an independent predictor for both modified Rankin's Score 0-2 (52%) [exp(β) = .984] and mRS 0-1 outcome (32%) [exp(β) = .828] in addition to admission National Institutes of Health Stroke Scale, age and carotid plaque burden. CAPATd-maximum ipsilateral was acceptably accurate (Area under the Receiver operating characteristic Curve was .607, P = .0109 for mRS 0-2 and .613, P = .0102 for mRS 0-1). Ipsilateral CAPATd ≥ -25 HU predicted both mRS >3 and mRS >2 with usable sensitivity (59.8% and 66.07%) and specificity (63.6% and 59.68%). In conclusion, higher maximum CAPATd measured on emergency CTA indicates poorer functional prognosis in acute stroke patients treated with IV-tPA.

Automated Intracranial Clot Detection: A Promising Tool for Vascular Occlusion Detection in Non-Enhanced CT

(1) Background: to test the diagnostic performance of a fully convolutional neural network-based software prototype for clot detection in intracranial arteries using non-enhanced computed tomography (NECT) imaging data. (2) Methods: we retrospectively identified 85 patients with stroke imaging and one intracranial vessel occlusion. An automated clot detection prototype computed clot location, clot length, and clot volume in NECT scans. Clot detection rates were compared to the visual assessment of the hyperdense artery sign by two neuroradiologists. CT angiography (CTA) was used as the ground truth. Additionally, NIHSS, ASPECTS, type of therapy, and TOAST were registered to assess the relationship between clinical parameters, image results, and chosen therapy. (3) Results: the overall detection rate of the software was 66%, while the human readers had lower rates of 46% and 24%, respectively. Clot detection rates of the automated software were best in the proximal middle cerebral artery (MCA) and the intracranial carotid artery (ICA) with 88-92% followed by the more distal MCA and basilar artery with 67-69%. There was a high correlation between greater clot length and interventional thrombectomy and between smaller clot length and rather conservative treatment. (4) Conclusions: the automated clot detection prototype has the potential to detect intracranial arterial thromboembolism in NECT images, particularly in the ICA and MCA. Thus, it could support radiologists in emergency settings to speed up the diagnosis of acute ischemic stroke, especially in settings where CTA is not available.

Acute stroke in familial Mediterranean fever: An analysis of 23 new cases and systematic review of the literature

OBJECTIVE

The nature of neurovascular involvement in cases of familial Mediterranean fever (FMF) has not been adequately clarified.

METHODS AND PATIENTS

Clinical features, infarct topography, vascular status, and stroke etiology were prospectively determined in 35 acute neurovascular events that occurred in 23 FMF patients. Clinicoradiological features were compared with an age- and gender-matched control group of 115 acute stroke patients. Characteristics of additional FMF and acute stroke cases (6 episodes in 6 patients) identified from a systematic literature review (PROSPERO registration no: CRD420212264820) were also analyzed.

RESULTS

There were 27 acute ischemic stroke episodes in 19 patients, 7 transient ischemic attack episodes in 3 patients, and 1 patient with a single episode of parietal hematoma in our cohort. Twenty (74%) ischemic stroke episodes in 12 patients were cryptogenic. Ten of these 12 cases had a previous FMF diagnosis and were taking colchicine. There was no significant difference in the FMF group in terms of the presence of vascular risk factors and angiography-documented disease in comparison to controls. Cerebral distal artery involvement was significantly prevalent in FMF (78% vs 45%, P = .002). Especially, midbrain central deep perforating territory involvement was higher (30% vs 1%, P < .001). The long-term prognosis (median 8.5 years) under antiplatelet agents and colchicine is favorable.

DISCUSSION

The acute stroke phenotype in FMF cases is herein described for the first time. Several clinicoradiological features such as thrombotic lacunar infarcts located in the central mesencephalon seem so typical that we recommend searching for FMF mutations in geographic regions where FMF is common.

Prognostic capacity of hyperdense middle cerebral artery sign in anterior circulation acute ischaemic stroke patients receiving reperfusion therapy: a systematic review and meta-analysis

Pre-intervention CT imaging-based biomarkers, such as hyperdense middle cerebral artery sign (HMCAS) may have a role in acute ischaemic stroke prognostication. However, the clinical utility of HMCAS in settings of reperfusion therapy and the level of prognostic association is still unclear. This systematic review and meta-analysis investigated the association of HMCAS sign with clinical outcomes and its prognostic capacity in acute ischaemic stroke patients treated with reperfusion therapy. Prospective and retrospective studies from the following databases were retrieved from EMBASE, MEDLINE and Cochrane. Association of HMCAS with functional outcome, symptomatic intracerebral haemorrhage (sICH) and mortality were investigated. The random effect model was used to calculate the risk ratio (RR). Subgroup analyses were performed for subgroups of patients receiving thrombolysis (tPA), mechanical thrombectomy (EVT) and/or combined therapy (tPA + EVT). HMCAS significantly increased the rate of poor functional outcome by 1.43-fold in patients (RR 1.43; 95% CI 1.30-1.57; p < 0.0001) without any significant differences in sICH rates (RR 0.91; 95% CI 0.68-1.23; p = 0.546) and mortality (RR 1.34; 95% CI 0.72-2.51; p = 354) in patients with positive HMCAS as compared to negative HMCAS. In subgroup analyses, significant association between HMCAS and 90 days functional outcome was observed in patients receiving tPA (RR 1.53; 95% CI 1.40-1.67; p < 0.0001) or both therapies (RR 1.40; 95% CI 1.08-1.80; p = 0.010). This meta-analysis demonstrated that pre-treatment HMCAS increases risk of poor functional outcomes. However, its prognostic sensitivity and specificity in predicting long-term functional outcome, mortality and sICH after reperfusion therapy is poor.

Advances in imaging acute ischemic stroke: evaluation before thrombectomy

Recent advances in neuroimaging have demonstrated significant assessment benefits and appropriate triage of patients based on specific clinical and radiological features in the acute stroke setting. Endovascular thrombectomy is arguably the most important aspect of acute stroke management with an extended time window. Imaging-based physiological information may potentially shift the treatment paradigm from a rigid time-based model to a more flexible and individualized, tissue-based approach, increasing the proportion of patients amenable to treatment. Various imaging modalities are routinely used in the diagnosis and management of acute ischemic stroke, including multimodal computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, these imaging methods should provide information beyond the presence or absence of intracranial hemorrhage as well as the presence and extent of the ischemic core, collateral circulation and penumbra in patients with neurological symptoms. Target mismatch may optimize selection of patients with late or unknown symptom onset who would potentially be eligible for revascularization therapy. The purpose of this study was to provide a comprehensive review of the current evidence about efficacy and theoretical basis of present imaging modalities, and explores future directions for imaging in the management of acute ischemic stroke.

Quantitative Assessment of Hyperdense Sign Measured by Hounsfield Units is Associated with Unsuccessful Mechanical Thrombectomy

PURPOSE

Despite advancement in mechanical thrombectomy (MT) techniques, 10-30% of MT for large vessel occlusions (LVO) are unsuccessful. Current prediction models fail to address the association between patient-specific factors and reperfusion. We aimed to evaluate objective, easily reproducible, admission clinical and radiological biomarkers that predict unsuccessful MT.

METHODS

We analyzed consecutive anterior LVO MT patients at two comprehensive stroke centers. The primary outcome was unsuccessful reperfusion defined by a modified thrombolysis in cerebral infarction (mTICI) score of 0-2a. We quantitatively assessed the hyperdense vessel sign by measuring Hounsfield units (HU) on admission computed tomography (CT). Receiver operating characteristic (ROC) curves were plotted to estimate the predictive value of quantitative hyperdense middle cerebral artery (MCA) measurements (delta and ratio) and of the final model for mTICI scores. We performed multivariable logistic regression to analyze associations with outcomes.

RESULTS

Out of 348 patients 87 had unsuccessful MT. Smoking, difficult arch, vessel tortuosity, vessel calcification, diminutive vessels, truncal M1 occlusion, delta HU and HU ratio were significantly associated with unsuccessful MT in the univariate analysis. When we fitted two separate multivariate models including all significant variables and a HU measurement; delta HU <6 (odds ratio, OR = 2.07, 95% confidence intervals, CI 1.09-3.92) and HU ratio ≤1.1 (OR = 2.003, 95% CI 1.05-3.81) were independently associated with failed MT after adjustment for smoking, diminutive vessels, vessel tortuosity, and difficult arch. The area under the curve AUC<9 of the final model was 0.717.

CONCLUSION

Novel radiological biomarkers on CT, CT angiography (CTA) and digital subtraction angiography (DSA) may help identify patients refractory to standard MT and prepare interventionalists for using additional alternative methods. Quantitative assessment of HU (delta and ratio) may be important in developing objective prediction tools for unsuccessful MT.

The Quantitative Evaluation of the Density of the Segmental Branches of the MCA in Acute Ischemic Stroke Patients

AIM

The aim of this study was to assess the density of the segmental branches of the middle cerebral artery (MCA) quantitatively as a predictor of acute ischemic stroke in patients without definitive infarct findings at cerebral parenchyma by non-contrast computed tomography (CT).

CLINICAL RATIONALE FOR THE STUDY

The clinical rationale for the study is to evaluate if the measurement of Sylvian fissure dot sign (SDS) would help early management of patients with stroke at the emergency department.

METHODS

Computed tomography scans of 101 patients admitted to the emergency department with stroke symptoms and/or signs were included in the study, retrospectively. In the patient group, the quantitative density of the segmental branches of the MCA in the Sylvian fissure was measured on the affected side and the contralateral side.

RESULTS

Quantitative density of SDS was significantly higher on the ischemic side of the brain. Receiver operating characteristic (ROC) analysis showed a cut-off value of 38.5 Hounsfield units (HU) as a predictor for acute ischemic stroke, with a sensitivity and specificity of 79% and 92%, respectively.

CONCLUSION

Quantitative density of SDS on the affected side in patients without definitive cerebral infarct findings of parenchyma can be used in the emergency room as an objective predictor sign for the diagnosis of acute ischemic stroke. Considering this finding in the differential diagnosis of acute stroke patients in the emergency room has the potential to improve their clinical management, particularly for the patients without early parenchymal and vascular signs of stroke.

Intravenous thrombolysis for ischemic stroke with hyperdense middle cerebral artery sign: A meta-analysis

Hyperdense middle cerebral artery sign (HMCAS) on admitting to neuroimaging is reported to have prognostic value for poor outcomes after thrombolysis, while evidence from studies comprising a sufficiently large sample size is limited. To detect prognostic predictors after thrombolysis could help improve therapeutic clinical strategies for acute ischemic stroke. We included prospective and retrospective studies of stroke patients that were treated with intravenous thrombolysis, in which functional outcomes (ie, a modified Rankin scale [mRS]) and systematic intracranial hemorrhage (sICH) were assessed in relation to HMCAS during pretreatment head CT. Random-effects models were used to calculate pooled risk ratios (RR) of poor outcomes and sICH for HMCAS patients as compared to patients without HMCAS. Eleven studies permitted identification of 11 818 patients. The risk of poor outcome at 3 months in the HMCAS-positive group was 1.56-fold the negative group (RR, 1.56; 95% CI 1.50-1.62; P < .001). The sICH risk when comparing both groups was found to be non-significant. Sensitivity analysis regarding studies performing thrombolysis within 3 hours also exhibited significant differences in their functional outcomes (RR, 1.56, 95% CI 1.49-1.62; P < .001) in patients with HMCAS as compared to non-HMCAS patients, although this was true for sICH risk. The presence of HMCAS on pretreatment CT predicts a poor outcome at 3 months after intravenous thrombolysis, while its relationship with the incidence of sICH was found to have no statistic value. Our study implies that more aggressive treatment should be considered for HMCAS patients.

The Effect of Clot Volume and Permeability on Response to Intravenous Tissue Plasminogen Activator in Acute Ischemic Stroke

BACKGROUND AND AIMS

The characteristics of clot causing acute ischemic stroke, such as size, content, and location, are among the main determinants of response to intravenous tissue plasminogen activator [IV tPA]. Clot heterogeneity and permeability are under-recognized features that might provide additional information in predicting the efficacy of IV tPA.

METHODS AND PATIENTS

Patients with proximal middle cerebral artery occlusion treated with "IV tPA alone" were included. The mean Hounsfield's unit (HU) value, as objective measure of clot attenuation, and its standard deviation (SD), as proposed measure of clot heterogeneity, were obtained. The difference in HU values between CT Angiography and CT was defined as "clot permeability", or "perviousness'. The size (length and volume-mm3) of pre-clot pouch and occluding clot along with ASPECT score and Maas' silvian and leptomeningeal collateral score were measured.

RESULTS

The study included 84 cases (44 women, age: 68 ± 14 years, pretPA NIHSS: 16 ± 5). Patients with excellent response to tPA (31%) had lower thrombus volume (37.54 ± 32.37 versus 63.49 ± 37.36, P = .009) and heterogeneity (4.05 ± 1.49 versus 5.35 ± 2.34, P = .011), along with higher clot permeability (48 ± 35.48 to 31.32 ± 18.62, P = .006). However, significance of permeability did not survived in the regression analysis with adjustment for NIHSS (β:-.296, P = .003); clot volume (β:-.240, P = .014) and collateral status (β:.346, P < .001). In patients with good prognosis, clot volume was significantly lower (37.76 ± 30.08 versus 67.57 ± 37.83, P < .001), whereas permeability was significantly higher (43.97 ± 32.33 versus 31.13 ± 19.01, P = .026). However, this effect did not persist in the regression analysis after adjustment for NIHSS (β:-.399, P < .001), collateral status (β: .343, P < .001) and clot volume (β:-.297, P = .001). Clot permeability was significantly higher (45.78 ± 36.34 versus 33 ± 20.2, P = .045) and heterogeneity was lower (4.1 ± 1.55 to 5.27 ± 2.32, P = .028) in patients with dramatic response to tPA (27%). In patients responding positively to IV tPA (48%), clot permeability was numerically higher (39.85 ± 31.79 to 33.47 ± 19.28, P = .268), while clot volume (48.15 ± 34.5 to 62.07 ± 39.62, P = .093) was lower. Clot volume, permeability and heterogeneity did not show a significant difference in any (38.1%) or symptomatic (8.3%) bleeders after IV tPA. The chance of IV tPA to be beneficial increased in patients with clot volume lower than 45 mm³, with an increased likelihood of this benefit to be observed within the first day after IV tPA. Our detailed explorative ROC analysis was not able to detect a volume threshold above which the positive effect of IV tPA disappeared.

CONCLUSION

Clot volume is critical for the effectiveness of IV tPA in acute ischemic stroke. Clot permeability and heterogeneity may modify its effect. CT technologies, which are readily available when evaluating a stroke patient in an emergency setting, provide us with useful parameters regarding the size, permeability and heterogeneity of the clot.

Computed tomographic angiography in stroke and high-risk transient ischemic attack: Do not leave the emergency department without it!

Stroke is a major cause of morbidity and mortality worldwide, and effective treatment requires rapid diagnosis and recognition of relevant vascular lesions. In this review we will discuss the usefulness and versatility of computed tomography angiography in the setting of stroke, be it ischemic or hemorrhagic, minor or disabling. Furthermore, we also highlight how we use computed tomography angiography in decision making in transient ischemic attacks, acute disabling ischemic stroke, and hemorrhagic stroke.

Multiplanar computed tomography reconstruction to aid in recognition of the middle cerebral artery "Dot" sign: The sagittal string sign

While non-contrast head computed tomography is effective in detecting blood, it is not sensitive in diagnosing hyperacute ischemic stroke. One neuroradiologic marker for early thromboembolic occlusion of the distal middle cerebral artery is the middle cerebral artery "dot" sign. The "dot" seen on the typical axial plane represents a hyperdensity of the middle cerebral artery in the Sylvian fissure. A review of medical literature was conducted via PubMed utilizing search phrases "MCA," "dot," and "sign." The review was limited to the intravenous tissue-type plasminogen activator era, 1996 and on. Articles were analyzed to determine the use of the sagittal plane of non-contrast head computed tomography to locate the middle cerebral artery "dot" sign. The search terms yielded 11 results which revealed that computed tomography reconstruction and sagittal planes were not used for detection of the middle cerebral artery "dot" signs. Our patient had no known past medical history. The initial non-contrast head computed tomography was read as having a hypodensity in the right insular region and a middle cerebral artery "dot" sign. Multiplanar reconstruction of the computed tomography demonstrated a hyperdense sagittal string-like appearance of the middle cerebral artery along the Sylvian fissure. Computed tomography angiography confirmed the M2 occlusion. This is the first report of using the head computed tomography sagittal plane for diagnosis of the middle cerebral artery "dot" sign. Incorporating multiplanar reconstruction and producing the sagittal plane may lead to a higher sensitivity of the middle cerebral artery "dot" sign. Further studies incorporating a patient cohort will be needed to determine how much the sagittal plane view augments predictive value of the middle cerebral artery "dot" sign.

Dual-Energy Computed Tomography in Stroke Imaging: Technical and Clinical Considerations of Virtual Noncontrast Images for Detection of the Hyperdense Artery Sign

OBJECTIVE

The technical feasibility of virtual noncontrast (VNC) images from dual-energy computed tomography (DECT) for the detection of the hyperdense artery sign (HAS) in ischemic stroke patients was investigated.

METHODS

True noncontrast (TNC) scans of 60 patients either with or without HAS (n = 30 each) were investigated. Clot presence and characteristics were assessed on VNC images from DECT angiography and compared with TNC images. Clot characterization included the level of confidence for diagnosing HAS, a qualitative clot burden score, and quantitative attenuation (Hounsfield unit [HU]) measurements.

RESULTS

Sensitivity, specificity, and accuracy of VNC for diagnosing HAS were 97%, 90%, and 93%, respectively. No significant differences were found regarding the diagnostic confidence (P = 0.18) and clot burden score (P = 0.071). No significant HU differences were found among vessels with HAS in VNC (56 ± 7HU) and TNC (57 ± 8HU) (P = 0.691) images.

CONCLUSIONS

Virtual noncontrast images derived from DECT enable an accurate detection and characterization of HAS.

Intracranial Thrombus Morphology and Composition Undergoes Time-Dependent Changes in Acute Ischemic Stroke: A CT Densitometry Study

The aim of our study was to assess whether cerebral artery clots undergo time-dependent morphological and compositional changes in acute ischemic stroke. We performed a retrospective chart review of patients admitted within 5 h from symptom onset to three European stroke centers and evaluated non-contrast-enhanced CT (NECT) for hyperdense artery signs (HAS) in 2565 scans. The occlusion site, density of HAS expressed in Hounsfield units (HU), area of HAS, and relative density (rHU) (HU clot/HU non-affected artery) were studied and related to time from symptom onset, clinical severity, stroke etiology, and laboratory parameters. A HAS was present in the middle cerebral artery (MCA) in 185 (7.2%) and further explored. The mean time from symptom onset to CT was 100 min (range 17-300). We found a time-dependent loss of density in the occluded M1 segment within the first 5 h (N = 118, 95% CI [-15, -2], p = 0.01). Further, the thrombus area in the M2 segment decreased with time (cubic trend N = 67, 95% CI [-63, -8], p = 0.02). Overall, and especially in the M2 segment, a lower clot area was associated with higher fibrinogen (-21.7%, 95% CI [-34.8, -5.8], p = 0.009). In conclusion, our results disclosed time-dependent changes of intracranial thrombi with regard to occlusion site, density and area.

Fibrinogen consumption is related to intracranial clot burden in acute ischemic stroke: a retrospective hyperdense artery study

BACKGROUND

Understanding the underlying mechanism of thrombus formation and its components is critical for effective prevention and treatment of ischemic stroke. The generation of thrombotic clots requires conversion of soluble fibrinogen to an insoluble fibrin network. Quantitative features of intracranial clots causing acute ischemic stroke can be studied on non-contrast enhanced CT (NECT). Here, we evaluated on-admission fibrinogen and clot burden in relation to stroke severity, final infarct volume and in-hospital mortality.

METHODS

We included 132 consecutive patients with ischemic stroke and presence of hyperdense artery sign admitted within 6 h from symptom onset. Radiological parameters including clot area (corresponding to clot burden) and final infarct volume were manually determined on NECT. National Institute of Health Stroke Scale (NIHSS) was used to quantify disease severity and short-term outcome.

RESULTS

Median patient age was 77, 58 % were women, and 63 % had an occlusion of the proximal middle cerebral artery segment. Thrombolysis was performed in 60 % and thrombectomy in 44 %. We identified several independent associations. Higher fibrinogen levels on admission were associated with smaller clot burden (p = 0.033) and lower NIHSS on admission (p = 0.022). Patients with lower fibrinogen had a higher clot burden (p = 0.028) and greater final infarct volume (p = 0.003). Higher fibrinogen was associated with a lower risk of in-hospital death or NIHSS score >15 if discharged alive (p = 0.028).

CONCLUSIONS

Our study suggests that intracranial clot burden in acute ischemic stroke is associated with fibrinogen consumption, and shows a complex relationship with disease severity, infarct size and in-hospital survival.

Hyperdense Artery Sign, Clot Characteristics, and Response to Intravenous Thrombolysis in Han Chinese People with Acute Large Arterial Infarction

BACKGROUND

Whether the presence of hyperdense artery sign (HAS) correlates with clot characteristics and response to intravenous thrombotic therapy (IVT) remains to be determined. Given that the existent literature was mainly from the Western nations, the current study aimed to examine the relationships among HAS, clot characteristics, and outcome of IVT in a Han Chinese sample in Taiwan. The specific objectives are (1) to correlate HAS with clot characteristics and (2) to explore relationships between HAS and effectiveness/complication of IVT.

METHODS

We enrolled 75 patients treated with IVT following acute large arterial infarctions. All patients had a baseline brain computed tomography and a follow-up image at 24 hours after thrombolysis. Correlations were explored between HAS and clot characteristics. Multivariable logistic regressions were employed to examine the relationships between HAS and response to IVT at 24 hours, including early improvement and all forms of intracerebral hemorrhage (ICH).

RESULTS

In this Han Chinese sample in Taiwan, 50.7% of the patients had HAS and 64% had early improvements following IVT. Those with HAS tended to have clots lodging at main trunks of cerebral arteries but no significant associations were found between HAS and stroke etiology. In multivariable logistic regressions, HAS predicted neither early improvement nor ICH complication.

CONCLUSIONS

Instead of clot etiology, we found that it might be clot location that correlated with HAS. HAS was not associated with early improvement or ICH complication after IVT in this Han Chinese sample. We also showed that some other patient characteristics were likely to influence outcomes of IVT, which warrant clinical attention.