Diffusion-weighted Imaging Lesion Research Articles

Atherogenic Index of Plasma Predicts Early Recurrent Ischemic Lesion in Acute Ischemic Stroke

Background: Atherogenic index of plasma (AIP) is an index representing the lipid profile of atherogenic dyslipidemia and has been shown to be associated with various atherosclerosis, metabolic diseases, and cardiovascular diseases. However, studies in patients with cerebrovascular disease are still insufficient. In this study, we evaluated the association between AIP and early recurrent ischemic lesions (ERILs) in patients with acute ischemic stroke (AIS).Methods: We included consecutive patients with AIS between 2010 and 2016. ERILs were defined as new diffusion-weighted imaging lesions outside the initial symptomatic lesion area. AIP was calculated using the following formula: AIP=log (triglyceride [mg/dL]/high-density lipoprotein cholesterol [mg/dL]). For subgroup analysis according to stroke mechanism, participants were classif ied into the following four groups: intracranial-large artery atherosclerosis (LAA), extracranial- LAA, cardioembolism, and cryptogenic stroke.Results: A total of 182 patients with AIS were evaluated (median age: 72 years, median initial NIHSS score: 4 [2-13]). In the multivariable analysis, AIP (adjusted odds ratio [aOR], 3.73; 95% confidence interval [CI], 1.01-13.82) was closely associated with ERIL after adjusting confounders. Age and initial NIHSS score were also related to ERIL. Among the four stroke mechanisms, only extracranial-LAA showed significant differences in AIP values between patients with and without ERIL (<i>p</i>=0.028).Conclusion: High AIP was closely related to ERIL in patients with AIS, especially extracranial-LAA stroke. Judging from our results, AIP seems to be involved in the development of new lesions in AIS patients through the mechanisms of atherosclerosis.

Tissue perfusion of the kurtosis/diffusion mismatch differs from the central core and peripheral regions in acute cerebral infarction patients.

Despite its wide adoption in stroke imaging, the diffusion-weighted imaging (DWI) lesion is heterogeneous. The emerging diffusion kurtosis imaging (DKI) has been postulated to resolve the graded DWI lesion. To determine the perfusion characteristics of the central infarction core, kurtosis/diffusion mismatch, and peripheral regions. Patients with acute ischemic stroke underwent DWI, DKI, and perfusion-weighted imaging (PWI) scans. The patients were divided into mean kurtosis (MK)/mean diffusivity (MD) match and mismatch groups. Perfusion parameters were measured in the MK/MD lesion and peripheral areas in the MK/MD match group. We also analyzed perfusion status in the MK/MD lesion mismatch area for the mismatch group. A total of 40 eligible patients (24 MK/MD match and 16 MK/MD mismatch) were enrolled in the final data analysis. The MTT and TTP progressively decreased, while the cerebral blood flow (CBF) and cerebral blood volume (CBV) increased from the central to peripheral areas. In addition, CBF in the MK/MD mismatch region was significantly higher than that in the central region (P < 0.05), but similar to the peripheral region. Furthermore, CBV in the MK/MD mismatch region did not differ significantly from that of the central region, but both were significantly lower than that of the peripheral area (P < 0.05). The MK/MD mismatch region had blood flow similar to the peripheral region but with a reduced blood volume, indicating that it was less ischemic from the infarction core, albeit insufficient collateral circulation.

Accuracy of CT Perfusion-Based Core Estimation of Follow-up Infarction: Effects of Time Since Last Known Well.

To assess the accuracy of baseline CT perfusion (CTP) ischemic core estimates. From SELECT (Optimizing Patient Selection for Endovascular Treatment in Acute Ischemic Stroke), a prospective multicenter cohort study of imaging selection, patients undergoing endovascular thrombectomy who achieved complete reperfusion (modified Thrombolysis In Cerebral Ischemia score 3) and had follow-up diffusion-weighted imaging (DWI) available were evaluated. Follow-up DWI lesions were coregistered to baseline CTP. The difference between baseline CTP core (relative cerebral blood flow [rCBF] <30%) volume and follow-up infarct volume was classified as overestimation (core ≥10 mL larger than infarct), adequate, or underestimation (core ≥25 mL smaller than infarct) and spatial overlap was evaluated. Of 101 included patients, median time from last known well (LKW) to imaging acquisition was 138 (82-244) minutes. The median baseline ischemic core estimate was 9 (0-31.9) mL and median follow-up infarct volume was 18.4 (5.3-68.7) mL. All 6/101 (6%) patients with overestimation of the subsequent infarct volume were imaged within 90 minutes of LKW and achieved rapid reperfusion (within 120 minutes of CTP). Using rCBF <20% threshold to estimate ischemic core in patients presenting within 90 minutes eliminated overestimation. Volumetric correlation between the ischemic core estimate and follow-up imaging improved as LKW time to imaging acquisition increased: Spearman ρ <90 minutes 0.33 (p = 0.049), 90-270 minutes 0.63 (p < 0.0001), >270 minutes 0.86 (p < 0.0001). Assessment of the spatial overlap between baseline CTP ischemic core lesion and follow-up infarct demonstrated that a median of 3.2 (0.0-9.0) mL of estimated core fell outside the subsequent infarct. These regions were predominantly in white matter. Significant overestimation of irreversibly injured ischemic core volume was rare, was only observed in patients who presented within 90 minutes of LKW and achieved reperfusion within 120 minutes of CTP acquisition, and occurred primarily in white matter. Use of a more conservative (rCBF <20%) threshold for estimating ischemic core in patients presenting within 90 minutes eliminated all significant overestimation cases. ClinicalTrials.gov: NCT03876457.

Clinical Impact and Predictors of Diffusion Weighted Imaging(DWI) Reversal in Stroke Patients with Diffusion Weighted Imaging Alberta Stroke Program Early CT Score0-5 Treated by Thrombectomy : Diffusion Weighted Imaging Reversal in Large Volume Stroke.

To determine whether reversal of DWI lesions (DWIr) on the DWI-ASPECTS (diffusion weighted imaging Alberta Stroke Program CT Score) template should serve as apredictor of 90-day clinical outcome in acute ischemic stroke (AIS) patients with pretreatment diffusion-weighted imaging (DWI)-ASPECTS0-5 treated with thrombectomy, and to determine its predictors in current practice. We analyzed data of all consecutive patients included in the prospective multicenter national Endovascular Treatment in Ischemic Stroke Registry between 1 January 2015 and 31 December 2020 with apremorbid mRS ≤ 2, who presented with apretreatment DWI-ASPECTS 0-5score, underwent thrombectomy and had an available 24 h post-interventional MRI follow-up. Multivariable analyses were performed to evaluate the clinical impact of DWIr on early neurological improvement (ENI), 3‑month modified Rankin scale (mRS) score distribution (shift analysis) and to define independent predictors of DWIr. Early neurological improvement was detected in 82/211 (41.7%) of patients while 3‑month functional independence was achieved by75 (35.5%) patients. The DWI reversal (39/211, 18.9%) resulted an independent predictor of both ENI (aOR3.6, 95% CI 1.2-7.7; p0.018) and 3‑month clinical outcome (aOR for mRS shift:2.2, 95% CI 1-4.6; p0.030). Only successful recanalization (mTICI2c-3) independently predicted DWIr in the studied population (aOR3.3, 95% CI 1.3-7.9; p0.009). The DWI reversal occurs in anon-negligible proportion of DWI-ASPECTS0-5 patients subjected to thrombectomy and significantly influences clinical outcome. The mTICI2c-3 recanalization emerged as an independent DWIr predictor.

The remains of the day: neuropsychological findings in postacute transient global amnesia.

Current clinical diagnostic criteria of transient global amnesia (TGA) require the episode to completely resolve within 24h. Small case series investigating the neuropsychological profiles obtained during the first days after TGA are inconclusive, with some suggesting the persistence of memory deficits. In this retrospective observational study, neuropsychological data of 185 TGA patients obtained during the first days following an attack were analysed. Data of cognitive functions assessed in at least 50 patients were evaluated and dichotomised according to z-values as "impaired" or "unimpaired". Moreover, the results of magnetic resonance imaging (MRI) were collected. Neuropsychological assessment was performed within the first 3days after TGA in 158 (85.4%) of all patients. The majority of patients showed no significant neuropsychological sequelae in the postacute phase of TGA. However, Mini-Mental Status Examination showed impairment in 22.6% of 159 patients, and we found subtle reductions of patients' performance in tests of verbal long-term memory and executive function in 16.3-24.6% of patients. Patients with hippocampal diffusion-weighted imaging (DWI) lesions performed significantly worse in a verbal recognition task than those without DWI lesions. Our findings reflect subtle performance reductions in different cognitive domains in a small subgroup of TGA patients. This implies that the gradual resolution of subclinical symptoms may take longer than the 24h required as maximum episode duration by current diagnostic criteria.

Diffusion-weighted imaging as predictor of acute ischemic stroke etiology.

Topographic patterns may correlate with causes of ischemic stroke. To investigate the association between diffusion-weighted imaging (DWI) and Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification. We included 1019 ischemic stroke patients. DWI were classified as: i) negative; ii) DWI single lesion (cortico-subcortical, cortical, subcortical ≥20 mm, or subcortical <20 mm); iii) scattered lesions in one territory (small scattered lesions or confluent with additional lesions); and iv) multiple lesions (multiple unilateral anterior circulation [MAC], multiple posterior circulation [MPC], multiple bilateral anterior circulation [MBAC], and multiple anterior and posterior circulations [MAP]). There was a relationship between DWI patterns and TOAST classification (p<0.001). Large artery atherosclerosis was associated with small, scattered lesions in one vascular territory (Odds Ratio [OR] 4.22, 95% confidence interval [95%CI] 2.61-6.8), MPC (OR 3.52; 95%CI 1.54-8.03), and subcortical lesions <20 mm (OR 3.47; 95%CI 1.76-6.85). Cardioembolic strokes correlated with MAP (OR 4.3; 95%CI 1.64-11.2), cortico-subcortical lesions (OR 3.24; 95%CI 1.9-5.5) and negative DWI (OR 2.46; 95%CI 1.1-5.49). Cryptogenic strokes correlated with negative DWI (OR 4.1; 95%CI 1,84-8.69), cortical strokes (OR 3.3; 95%CI 1.25-8.8), MAP (OR 3.33; 95%CI 1.25-8.81) and subcortical lesion ≥20 mm (OR 2.44; 95%CI 1,04-5.73). Lacunar strokes correlated with subcortical lesions diameter <20 mm (OR 42.9; 95%CI 22.7-81.1) and negative DWI (OR 8.87; 95%CI 4.03-19.5). Finally, MBAC (OR 9.25; 95%CI 1.12-76.2), MAP (OR 5.54; 95%CI 1.94-15.1), and MPC (OR 3.61; 95%CI 1.5-8.7) correlated with stroke of other etiologies. A relationship exists between DWI and stroke subtype.

Changes in Cerebral Blood Flow and Diffusion-Weighted Imaging Lesions After Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH) is a common subtype of stroke and places a great burden on the family and society with a high mortality and disability rate and a poor prognosis. Many findings from imaging and pathologic studies have suggested that cerebral ischemic lesions visualized on diffusion-weighted imaging (DWI) in patients with ICH are not rare and are generally considered to be associated with poor outcome, increased risk of recurrent (ischemic and hemorrhagic) stroke, cognitive impairment, and death. In this review, we describe the changes in cerebral blood flow (CBF) and DWI lesions after ICH and discuss the risk factors and possible mechanisms related to the occurrence of DWI lesions, such as cerebral microangiopathy, cerebral atherosclerosis, aggressive early blood pressure lowering, hyperglycemia, and inflammatory response. We also point out that a better understanding of cerebral DWI lesions will be a key step toward potential therapeutic interventions to improve long-term recovery for patients with ICH.

Perceived importance of silent cerebral ischemia following endovascular procedures

PurposeThe clinical significance of iatrogenic diffusion-weighted imaging lesions following endovascular procedures is currently not well understood, partly because they do not result in immediate clinical deficits (“silent brain infarcts” [SBI]) and often remain undiagnosed. Conversely, access site complications are well-documented. With the SILENT survey, we sought to gain an understanding of physicians' opinions regarding the relative importance of SBI compared to the more commonly discussed access site complications. MethodsSeven scenarios of access site complications of varying severity were provided. Within each scenario, participants were asked whether they would choose the access site complication or an increasing number of periprocedural SBI. Logistic regression clustered by respondent was performed to assess participant and scenario factors associated with preferential choice of SBI versus access site complications. Results67 participants (13 women; 19.4%) provided 469 responses to the survey. The majority (45; 67.2%) were neurointerventionalists. Regardless of scenario, any number of SBI was deemed unacceptable in 42.4% of cases, whereas 10.5% of physicians would accept >15 SBI to avoid any access site complications. Significant group differences for career stage (p=0.001) and specialty (p=0.007) for the number of tolerated SBI were observed. Regression analyses revealed that only hematoma severity was significantly associated with the willingness to accept an increasing number of SBI. ConclusionIn this survey, 4/10 physicians would accept even severe access site complications to avoid any SBI. The perceived importance of SBI among experienced physicians, and the uncertainty regarding their long-term sequelae, support their systematic assessment and reporting.

Inattentional blindness to DWI lesions in spontaneous intracerebral hemorrhage.

Inattentional blindness refers to when an individual fails to recognize an event or object due to their awareness being engaged in a different task and has been described in radiology. The purpose of this study is to determine whether the sensitivity of detecting diffusion-weighted imaging (DWI) lesions in spontaneous intracerebral hemorrhage (sICH) is reduced due to inattentional blindness. Using a prospective observational cohort, select sICH patients received an MRI scan within 72h of admission. The scans were subject to an "official read" that occurred as part of the routine workflow. Separately, each scan underwent two "preliminary research reads" with task-specific instructions to detect DWI lesions. A "final research read" via three-party adjudication was used to calculate sensitivity and specificity for detecting these lesions. Board-certified neuroradiologists blinded to the clinical history of the patients reviewed all imaging. Amongst 121 sICH participants with research MRI scans, 49.6% (n = 60) scans were noted to have DWI lesion on their "final research read." The "official read" detected these DWI lesions with a sensitivity of 65% (95% CI, 52-77%). In contrast, the "preliminary research read" sensitivity for readers 1 and 2 was 98% (CI 95%, 91 to 100%) and 87% (CI 95%, 75 to 94%), respectively. Both were significantly different (p < 0.05) from the sensitivity of the "official read." Given the increased sensitivity with task-specific instructions, our results suggest that inattentional blindness may be leading to the decreased detection of DWI lesions in patients with concomitant sICH.

The Significance of Atrial Fibrillation in Patients With Transient Global Amnesia.

Background and PurposeThe etiology of transient global amnesia (TGA) remains unclear in a large subset of patients. We aimed to determine the clinical and radiological characteristics of TGA-patients with suspected acute micro-embolic stroke on diffusion-weighted imaging (DWI).MethodsTGA-patients that had new DWI hippocampal lesions (DWI+) were compared to DWI negative TGA-patients (DWI–). Demographics, risk factors, clinical data, radiological data, and mortality were analyzed.ResultsOut of 83 patients diagnosed with TGA, 56 (65%) underwent MRI during the acute hospitalization and 26 (46%) had new hippocampal DWI lesions. DWI+ patients more often had a history of atrial fibrillation (AF, 26 vs. 7%, p = 0.04) but the frequency of other risk factors did not differ. None of the patients died, however, two DWI+ patients had subsequent stroke during a 2-year follow up and both had AF. In contrast, none of the DWI- patients had recurrent events.ConclusionAF is common among DWI+ TGA-patients. The presence of AF in patients with TGA could suggest an increased risk of subsequent stroke.

The Role of Carbon Dioxide in the Rat Acute Stroke Penumbra.

PurposeThe vasodilatory response to inhaled CO2 occurs in the acute stroke ischemic penumbra and may be a potential therapeutic modality.MethodsTwenty-two Sprague-Dawley rats were subjected to 90-min occlusion of the M2 segment of the middle cerebral artery (M2CAO) by endovascular technique. The animals were administered different C02 concentrations and scanned serially with 9.4 T MRI. Infarct tissue was determined by diffusion-weighted imaging (DWI) and hypoperfused tissue was determined by arterial spin labeling (PWI).Results4 animals were administered room air (RA)+ 6% CO2 (group 1), 6 animals RA+12% CO2 (Group 2) and 4 animals only RA (group 3). In the rats with CO2 administered (groups 1 and 2), the DWI lesion to cerebral hypoperfusion volume ratio (SD) at pre-CO2 administration, was 0.145(0.168), which increased to 0.708(0.731) during CO2 administration and reduced to 0.533(0.527) post-CO2 administration. In 9 of 10 rats the hypoperfused volume decreased when CO2 was administered. When CO2 was stopped the hypoperfused volume became larger again. Administration of RA+12% CO2 (Group 2) decreased the volume of CBF hypoperfusion significantly compared to the control group (95%CI: 0.084 ± 0.0213, p = 0.004).ConclusionInhaled CO2 appears to reduce the size of the hypoperfused tissue volume during acute stroke and may be a potential modality for treatment of acute ischemic stroke. These findings will nonetheless need to be validated in a larger cohort in other centers.

Diffusion-Weighted Imaging and Fluid-Attenuated Inversion Recovery Quantification to Predict Diffusion-Weighted Imaging-Fluid-Attenuated Inversion Recovery Mismatch Status in Ischemic Stroke With Unknown Onset.

Visual rating of diffusion-weighted imaging (DWI)-fluid-attenuated inversion recovery (FLAIR) mismatch can be challenging. We evaluated quantification of DWI and FLAIR to predict DWI-FLAIR mismatch status in ischemic stroke. In screened patients from the WAKE-UP trial (Efficacy and Safety of Magnetic Resonance Imaging-Based Thrombolysis in Wake-Up Stroke), we retrospectively studied relative DWI (rDWI SI) and FLAIR signal intensity (rFLAIR SI). We defined the optimal mean rFLAIR SI and interquartile range of the rDWI SI in the DWI lesion to predict DWI-FLAIR mismatch status. We investigated agreement between each quantitative parameter and the DWI-FLAIR mismatch and the association between both quantitative parameters. We evaluated the predictive value of the quantitative parameters for excellent functional outcome by logistic regression, adjusted for DWI lesion volume, treatment, age, and National Institutes of Health Stroke Scale score. In the rFLAIR and rDWI SI analysis, 213/369 and 241/421 subjects respectively had a DWI-FLAIR mismatch. A mean rFLAIR SI cutoff of 1.09 and interquartile range rDWI SI cutoff of 0.47 were optimal to predict the DWI-FLAIR mismatch with a sensitivity and specificity of 77% (95% CI, 71%-83%) and 67% (95% CI, 59%-74%), and 76% (95% CI, 70%-81%) and 72% (95% CI, 65%-79%), respectively. For both quantitative parameters, agreement with the DWI-FLAIR mismatch was fair (73%, κ=0.44 [95% CI, 0.35-0.54] for rFLAIR and 74%, κ=0.48 [95% CI, 0.39-0.56] for rDWI). Both quantitative parameters correlated moderately (Pearson R=0.54 [95% CI, 0.46-0.61]; P<0.001, n=367). The interquartile range rDWI SI (n=188), but not the mean rFLAIR SI (n=172), was an independent predictor of excellent functional outcome (odds ratio, 0.67 per 0.1 unit increase of interquartile range rDWI SI, 95% CI, 0.51-0.89, P=0.01). Agreement between the quantitative and qualitative approach may be insufficient to advocate DWI or FLAIR quantification as alternative for visual rating.

Abstract WMP61: Simultaneous Cerebral Blood Flow And Blood Volume Thresholding Produces Consistent Volumes Between Computed Tomography Perfusion Deconvolution Algorithms

Introduction: Computed tomography perfusion (CTP) allows estimation of infarct volume in patients with acute ischemic stroke, but significant differences have been reported between CTP deconvolution algorithms. Hypothesis: We hypothesized that cerebral blood flow (CBF) and blood volume (CBV) dual thresholding estimates infarct volumes accurately and remain consistent between deconvolution algorithms. Methods: Data were from the open-source ISLES dataset, which comprised of patients with acute ischemic stroke who received admission CTP and infarct delineated from diffusion-weighted imaging (DWI) acquired &lt;3 hours of CTP and prior to treatment. CBF and CBV maps were calculated with a model-independent (filtered Fourier Transform) and a model-dependent (box-tail model) deconvolution algorithm using identical arterial input functions and Gaussian-filtered source images. Infarct was estimated using standard CBF&lt;30% relative to the contralateral hemisphere and a CBF&lt;30%+CBV&lt;38% dual threshold. Volume agreement between DWI and CTP lesions was determined by the mean difference ± standard deviation (DWI minus CTP). Consistency of CTP lesion volumes between deconvolution algorithms was characterized by the Pearson correlation (r) and a paired t-test. Results: Of 63 included patients, median DWI lesion volume was 28.0 (interquartile range: 13.3 to 57.2) ml. With model-independent and model-dependent deconvolution, respectively, mean differences were 35.7±40.4 ml and 10.9±47.6 ml using CBF&lt;30%, and 37.1±40.2 ml and 28.5±28.6 ml using CBF+CBV thresholding. Between model-independent and model-dependent CTP lesion volumes, Pearson correlation was moderate for CBF&lt;30% (r=0.645, p&lt;0.001) and excellent for CBF+CBV thresholding (r=0.903, p&lt;0.001). Paired t-tests were significant for both CBF&lt;30% and CBF+CBV thresholding (p&lt;0.001). Conclusions: CBF+CBV lesion volumes had improved consistency between deconvolution algorithms while achieving similar agreement to DWI lesion volumes compared to the standard CBF&lt;30% threshold. Further adjustment of CBF+CBV thresholds are required to improve accuracy to DWI lesion volumes but show promise in standardizing CTP lesion volumes across deconvolution algorithms.

Abstract TP133: Diabetes/hyperglycemia Is Associated With Poor Six-month Functional Outcomes, But Is Not Associated With The Development Of Microvascular Ischemic Lesions After Intracerebral Hemorrhage

Introduction: Ischemic lesions seen on diffusion weighted imaging (DWI) are associated with worsened outcomes after intracerebral hemorrhage (ICH) and are thought to arise due to microvascular damage. While hyperglycemia and diabetes mellitus contribute to small vessel disease, it is not known if these factors contribute to the development of DWI lesions and associated outcomes after ICH. Hypothesis: Indicators of diabetes/hyperglycemia will be associated with the development of DWI lesions and poor outcomes after ICH Methods: 1123 patients with MRI data from the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study were included. Predictors with p&lt;0.15 in univariate analyses were included in initial multivariable logistic regression models. Least absolute shrinkage and selection operator (LASSO) regression was used to identify final models. Results: In univariate analysis, no measure of diabetes or hyperglycemia (medical history of diabetes, insulin or non-insulin antidiabetic medication use, blood glucose obtained by emergency medical services, blood glucose on admission, fasting blood glucose, or hemoglobin A1c) was associated with the development of DWI lesions (p&gt;0.05). Blood glucose on admission was incorporated into the initial multivariable model (p&lt;0.15). Univariate analysis for poor six-month functional outcome (modified Rankin Score &gt;3) showed that history of diabetes (p&lt;0.001), blood glucose on admission (p=0.002), fasting blood glucose (p=0.049), and use of non-insulin antidiabetic medications (p=0.036) were associated with poor outcomes. Final multivariable logistic regression analyses are shown in Tables 1 and 2. Conclusions: While diabetes and hyperglycemia are associated with worsened outcomes after ICH, this relationship is unexpectedly not mediated by microinfarcts despite their association with cerebral small vessel disease.

Incidental DWI Lesions in Patients with Recent Small Subcortical Infarctions

ObjectivesIncidental acute ischemic lesions distinct from the primary neurological insult are identified on diffusion-weighted imaging (DWI) in a number of conditions where cerebral microvascular pathology plays a central role. Another major manifestation of cerebral small vessel disease (CSVD) is ischemic stroke named as recent small subcortical infarction (RSSI). In this study, we sought to identify the prevalence and predictors of incidental DWI lesions in patients with RSSI. Materials and MethodsWe retrospectively analyzed a consecutive series of acute ischemic stroke patients with DWI evidence of acute lesions solely localized to perforator artery territories. Images were evaluated for the presence of additional acute or subacute subcortical DWI lesions, apart from the symptomatic lesion. Clinical features including vascular risk factor burden, together with imaging markers of chronic CSVD, were compared among patients with and without incidental acute or subacute lesions. ResultsAmong 396 patients with no alternate stroke etiology additional incidental subcortical DWI bright lesions were identified in 74 (19%) cases. These lesions were primarily localized in the corona radiata, or centrum semiovale. Patients with incidental DWI lesions were more likely to have a history of hypertension, a higher white matter hyperintensities burden in the periventricular and subcortical region, higher perivascular spaces burden in the basal ganglia, multiple cerebral microbleeds, and multiple chronic lacunes. Presence of multiple chronic lacunes (OR 5.98, 95% CI 3.18-11.24) and ≥2 vascular risk factors (OR 2.03, 95% CI 1.05-3.91) stood out as features significantly associated with incidental DWI lesions in multivariate analysis. ConclusionsOur study shows that acute or subacute ischemic lesions can be incidentally detected in approximately one-fifth of patients with RSSI. This observation suggests that the course of CSVD might be more active, temporally and spatially, in a distinct subgroup of RSSI patients, specifically those with a higher chronic lacune and vascular risk factor burden.

Evaluation of right-to-left shunt on contrast-enhanced transcranial Doppler in patent foramen ovale-related cryptogenic stroke: Research based on imaging.

BACKGROUNDCardiogenic embolism caused by patent foramen ovale (PFO) is a common etiology of cryptogenic stroke (CS), particularly in young and middle-aged patients. Studies about right-to-left shunt (RLS) detection using contrast-enhanced transcranial Doppler (c-TCD) are numerous. According to the time phase and number of microbubbles detected on c-TCD, RLS can be classified and graded. We hypothesized that the characteristics of an infarction lesion on diffusion-weighted imaging differs when combining the type and grade of RLS on c-TCD in patients with PFO-related CS.AIMTo explore the characteristics of infarction lesions on diffusion-weighted imaging when combining the RLS type and grade determined by c-TCD.METHODSWe retrospectively evaluated CS patients from August 2015 to December 2019 at a tertiary hospital. In total, 111 PFO-related CS patients were divided according to whether RLS was permanent (microbubbles detected both at resting state and after the Valsalva maneuver) or latent (microbubbles detected only after the Valsalva maneuver) on c-TCD. Each group was subdivided into small, mild and large RLS according to the grade of shunt on c-TCD. A normal control group was composed of 33 patients who suffered from simple dizziness. Intragroup and intergroup differences were analyzed in terms of clinical, laboratory and diffusion-weighted imaging lesion characteristics. The correlation between RLS grade evaluated by c-TCD and size of PFO determined by transesophageal echocardiography were also analyzed.RESULTSIn 111 patients with PFO-related CS, 68 had permanent RLS and 43 had latent RLS. Clinical characteristics and laboratory tests were not significantly different among the permanent RLS, latent RLS and normal control groups. The proportion of patients with multiple territory lesions in the permanent RLS group (50%) was larger than that in the latent RLS group (27.91%; P = 0.021). Posterior circulation was more likely to be affected in the latent RLS group than in the permanent RLS group (30.23% vs 8.82%, P = 0.004). Permanent-large and latent-large RLS were both more likely to be related to multiple (Ptrend = 0.017 and 0.009, respectively), small (Ptrend = 0.035 and 0.006, respectively) and cortical (Ptrend = 0.031 and 0.033, respectively) lesions. The grade of RLS evaluated by c-TCD was correlated to the size of PFO determined by transesophageal echocardiography (r = 0.758, P < 0.001).CONCLUSIONDistribution of the infarct suggested the possible type of RLS. Multiple, small and cortical infarcts suggest large RLS induced by a large PFO.

Diffusion Weighted Imaging versus Contrast-enhanced T1-weighted Imaging Sequences in Inflammatory Demyelinating Diseases of Brain: A Cross-sectional Study

Introduction: Based on the literature, Contrast-enhanced T1-Weighted (CE T1WI) imaging sequence is considered as the gold standard radiological marker of active inflammatory demyelinating diseases of brain. However, administration of gadolinium based contrast agents is not always possible due to various comorbidities that the patient may suffer from, such as chronic kidney disease or contrast allergy. Diffusion Weighted Imaging (DWI) may potentially play a role in identifying disease activity in such cases without the need for intravenous administration of contrast. Aim: To compare signal intensity of lesions in inflammatory demyelinating diseases of brain on DWI with the status of enhancement on CE T1WI. Materials and Methods: This was a cross-sectional study conducted for two years from June 2015 to June 2017 among patients in the age group of two to 50 years presenting with clinicoradiological features of inflammatory demyelinating diseases in the Department of Radiodiagnosis in collaboration with Department of Neurology, Vardhman Mahavir Medical College (VMMC) and Safdarjung Hospital, New Delhi, India. Magnetic Resonance Imaging (MRI) of brain was done using different imaging sequences such as T1-Weighted Imaging (T1WI), T2-Weighted Imaging (T2WI), Fluid Attenuated Inversion Recovery (FLAIR), DWI, CE T1WI and were analysed for the lesions of demyelinating diseases. The signal intensity of demyelinating lesions on DWI were assessed against Contrast Enhancement on CE T1W1 imaging. Validity measures were estimated using appropriate formulae. Data was entered into Microsoft Excel software and qualitative variables were assessed for significance using Fisher’s-exact test. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy were assessed. Data analysis was done using Statistical Package for the Social Sciences (SPSS) software version 18.0. Results: There were a total of 73 contrast enhancement lesions. DWI hyperintensity showed 100% sensitivity, 60.9% specificity, positive predictive value of 84.7% and negative predictive value of 100% with accuracy of 87.7% whereas diffusion restriction showed 100% specificity, 12% sensitivity, positive predictive value of 100% and negative predictive value of 34.3% with accuracy of 39.7%. Conclusion: Hence, hyperintense lesions in DWI can be considered as a better screening tool and diffusion restriction can be considered as a diagnostic tool in active phase of inflammatory demyelinating diseases of brain, when compared to CE T1WI sequence.

Brain Tissue Conductivity in Focal Cerebral Ischemia.

Cerebral ischemia leads to oxygen depletion with rapid breakdown of transmembrane transporters and subsequent impaired electrolyte haemostasis. Electric properties tomography (EPT) is a new contrast in MRI which delivers information on tissue electrical conductivity. In the clinical realm it has been mostly used for tumour mapping. Ischemic cerebral stroke is another promising but neglected application. It might deliver additional information on tissue viability and possible response to therapy. The aim of this study was to demonstrate tissue conductivity in a rodent model of stroke. Further, we aimed to compare electric conductivity in ischemic and non-ischemic cerebral tissue. Two male Wistar rats were used in this study and were subjected to permanent MCAO. The animals were scanned in a 3 Tesla system (Philips Achieva/Best, the Netherlands) using a dedicated solenoid animal coil (Philips/Hamburg, Germany). In addition to diffusion weighted imaging (DWI), EPT was performed using a steady-state free-precession (SSFP) sequence (repetition time/echo time=4.5/2.3ms, measured voxel size=0.6×0.6×1.2 mm3, flip angle=38°, number of excitations=4). From the transceive phase ϕ of these SSFP scans, conductivity σ was estimated by the equation σ=Δϕ/(2μ0ω) with Δ the Laplacian operator, μ0 the magnetic permeability, and ω the Larmor frequency. Subsequently, a median filter was applied, which was locally restricted to voxels with comparable signal magnitude. The animals exhibited an infarct as demonstrated on DWI. Conductivity within the infarcted region was 60-70 % of the conductivity of not affected contralateral tissue (0.39±0.07S/m and 0.31±0.14S/m vs. 0.64±0.15S/m and 0.66±0.16S/m, respectively). Infarcted tissue exhibited decreased conductivity. Further in-vivo experiments with examination of the influence of reperfusion status and temporal evolution of the infarcted areas should be conducted. Depiction of the ischemic penumbra and possibly subclassification of the DWI lesion still seemsto be a fruitful target for further studies.

Cholesterol crystal embolism-related cerebral infarction: Magnetic resonance imaging and clinical characteristics.

Background and aimsCholesterol crystal embolism-related cerebral infarction (CCE-CI) is frequently misdiagnosed due to the lack of specific symptoms. To aid in differential diagnosis, this study comprehensively characterized the magnetic resonance imaging (MRI) and clinical manifestations of CCE-CI and compared these features to those of atherothrombotic cerebral infarction (ACI).MethodsThis single-center, retrospective, observational study was conducted at Kitasato University Hospital, Kanagawa, Japan. We identified 37 clinically or histopathologically confirmed CCE-CI cases and 110 ACI cases treated from January 2006 to May 2020. Groups were compared for mean age, sex ratio, clinical presentations, imaging manifestations, precipitating factors, comorbid conditions, medications, and smoking history.ResultsOf 37 eligible patients with CCE-CI, 10 (27.0%) received brain MRI, of which 8 (21.6%) exhibited high-intensity signals indicative of brain lesions on diffusion-weighted imaging (DWI). However, two patients with DWI lesions exhibited no detectable neurological abnormalities. Patients with CCE-CI frequently demonstrated bilateral DWI lesions involving the bilateral anterior and posterior circulation, a pattern absent in ACI (50% vs. 0%, p < 0.001). Compared to patients with ACI, CCE-CI patients also demonstrated significantly lower estimated glomerular filtration rate (p < 0.001) as well as more frequent eosinophilia (p = 0.006), atherosclerotic plaques ≥4-mm thick in the ascending aorta or proximal arch (p = 0.001), and aortic aneurysm (p < 0.001).ConclusionsPatients with CCE-CI develop multiple DWI lesions across several vascular territories, even in the absence of neurological symptoms. Comorbid aortic aneurysm may increase CCE-CI risk. These findings could help in the differential diagnosis of CCE-CI.

MR Three-Territory Sign in Cancer-Associated Hypercoagulation Stroke (Trousseau Syndrome): An Overlooked Diagnostic Feature: MR Three-Territory Sign.

Stroke in the setting of three-territory lesion pattern on magnetic resonance-diffusion-weighted imaging "three-territory sign" (TTS) is predominately due to cancer-associated hypercoagulation (CAH). Our goal is to determine the frequency with which "TTS" is overlooked as a diagnostic feature of cancer-associated hypercoagulation stroke. Over a 4-year period (October 2016 to October 2020), stroke admissions with magnetic resonance imaging defined three-territory diffusion-weighted imaging lesions were identified. Patients were prospectively accrued in an observational study from the neurology service at Hartford Hospital, a 938 bed facility with a comprehensive stroke center with 2792 stroke admissions during the study period. Twenty-two patients met selection criteria, 4 due to infectious endocarditis, 16 due to stroke from CAH and 2 with no identifiable etiology. Of the 16 CAH patients, 5 were male and 11 female, mean age=72 (range: 47 to 91). Cancer type (biopsy proven unless noted) was cholangiocarcinoma=3, adenocarcinoma of lung=3, adenocarcinoma of breast=1, pancreatic carcinoma=3 (2 biopsy, 1 ultrasound), adenocarcinoma, origin unknown=1, non-small cell carcinoma of lung=2, carcinoid=1, ovarian carcinoma=1, lung mass (not biopsied)=1. Malignancy was known in 7 and occult in 9 at stroke presentation. Consideration of malignancy-related hypercoagulation as the cause of stroke was appreciated in 1 of 16 radiology reports and in 4 of 16 neurology admission notes. TTS is a frequently missed diagnostic magnetic resonance feature in cancer-associated hypercoagulation stroke and often heralds occult malignancy.