Baseline Diffusion-weighted Imaging Research Articles

Automated acute ischemic stroke lesion delineation based on apparent diffusion coefficient thresholds.

Automated lesion segmentation is increasingly used in acute ischemic stroke magnetic resonance imaging (MRI). We explored in detail the performance of apparent diffusion coefficient (ADC) thresholding for delineating baseline diffusion-weighted imaging (DWI) lesions. Retrospective, exploratory analysis of the prospective observational single-center 1000Plus study from September 2008 to June 2013 (clinicaltrials.org; NCT00715533). We built a fully automated lesion segmentation algorithm using a fixed ADC threshold (≤620 × 10-6 mm2/s) to delineate the baseline DWI lesion and analyzed its performance compared to manual assessments. Diagnostic capabilities of best possible ADC thresholds were investigated using receiver operating characteristic curves. Influential patient factors on ADC thresholding techniques' performance were studied by conducting multiple linear regression. 108 acute ischemic stroke patients were selected for analysis. The median Dice coefficient for the algorithm was 0.43 (IQR 0.20-0.64). Mean ADC values in the DWI lesion (β = -0.68, p < 0.001) and DWI lesion volumes (β = 0.29, p < 0.001) predicted performance. Optimal individual ADC thresholds differed between subjects with a median of ≤691 × 10-6 mm2/s (IQR ≤660-750 × 10-6 mm2/s). Mean ADC values in the DWI lesion (β = -0.96, p < 0.001) and mean ADC values in the brain parenchyma (β = 0.24, p < 0.001) were associated with the performance of individual thresholds. The performance of ADC thresholds for delineating acute stroke lesions varies substantially between patients. It is influenced by factors such as lesion size as well as lesion and parenchymal ADC values. Considering the inherent noisiness of ADC maps, ADC threshold-based automated delineation of very small lesions is not reliable.

Predictive Value of a Novel Baseline Diffusion-Weighted Imaging Posterior Circulation Score in Endovascular Treatment of Patients with Acute Vertebrobasilar Occlusion

To investigate the predictive value of a novel posterior circulation score (novel-PC score) based on baseline posterior circulation diffusion-weighted imaging (DWI) for functional independence after endovascular treatment (EVT) in patients with acute vertebral-basilar artery occlusion (VBAO). The baseline DWI brain stem score (BSS), posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS), and the novel-PC score were evaluated separately. A modified Rankin scale(mRS) ≤2 at 90 days was defined as a prognostic indicator of functional independence. Modified Thrombolysis in Cerebral Infarction grade 2b or 3 was defined as surgical success. A total of 64 eligible patients were enrolled and divided into good and poor functional prognosis groups based on the mRS. The novel-PC score, BSS, and pc-ASPECTS (all P≤.001) were significantly better in the good functional prognosis group. The novel-PC score had a higher predictive value than BSS and pc-ASPECTS for 90-day functional independence (area under the receiver operating characteristic curve, 0.87 vs. 0.73 vs. 0.71; P<.05). Univariate binary logistic regression analysis showed that age (P=.006), Posterior National Institutes of Health Stroke Scale ≤18 (P<.001), BSS ≤2 (P=.008), pc-ASPECTS >7 (P=.002), and novel-PC score ≤5 (P=.001) were independently associated with function. Our novel-PC score, based on DWI, can independently predict functional prognosis in patients with acute VBAO after EVT. The novel-PC score based on baseline DWI was shown to be an independent predictor of function in patients with acute BVAO who are treated with EVT.

MRI Assessment of Brain Frailty and Clinical Outcome in Patients With Acute Posterior Perforating Artery Infarction.

Global brain health has gained increasing attention recently. Imaging markers of brain frailty have been related to functional outcomes in previous studies on anterior circulation; however, little data are available on imaging markers and posterior circulation. To investigate the impact of brain frailty on functional outcomes in patients with acute perforating artery infarction (PAI) of the posterior circulation. Prospective. One hundred patients (60.78 ± 9.51 years, 72% men) with acute posterior circulation PAI (determined by diffusion-weighted magnetic resonance imaging (MRI)/time-of-flight MR angiography). T1- and T2-weighted fast spin echo, T2-weighted fluid-attenuated inversion recovery, diffusion-weighted echo planar, gradient echo (susceptibility-weight imaging), and 3D time-of-flight MR angiography sequences at 3.0 T. Periventricular and deep white matter hyperintensities (WMH), enlarged perivascular spaces (EPVS) in the basal ganglia and centrum semiovale area, lacunes, cerebral microbleeds (CMB), and total brain frailty score by calculating the above imaging characters were rated visually by three radiologists with 9, 10, and 11 years of experience and one neuroradiologist with 12. Infarction volume was assessed using baseline diffusion-weighted imaging (DWI) data obtained within 24 hours of symptom onset. A modified Rankin Scale (mRS) score >1 on day 90 defined an adverse functional outcome. Associations between the imaging markers of brain frailty and functional outcomes were assessed. Fisher's exact test, Mann-Whitney U test, and multivariable binary logistic regression. A P value <0.05 was considered statistically significant. Adverse prognoses (mRS > 1) were observed in 34 (34%) patients. Infarction volume, periventricular WMH, deep WMH, basal ganglia EPVS, CMB, and the brain frailty score were significantly associated with adverse functional outcomes. An increased brain frailty score was significantly associated with unfavorable mRS score on day 90 (odds ratio 1.773, 95% confidence interval 1.237-2.541). Advanced MRI imaging markers of brain frailty, individually or combined as a total brain frailty score, were associated with worse functional outcomes after acute posterior circulation PAI. 3 TECHNICAL EFFICACY: Stage 3.

Multidelay Arterial Spin Labeling Versus Computed Tomography Perfusion in Penumbra Volume of Acute Ischemic Stroke.

Multidelay arterial spin labeling (ASL) is a novel perfusion method of ASL, with arterial transit time (ATT) calculated by multiple postlabeling delays to correct cerebral blood flow (CBF). We verify the accuracy of multidelay ASL in evaluating the ischemic penumbra and perfusion levels in patients with acute ischemic stroke, compared with computed tomography perfusion (CTP). Patients with acute ischemic stroke with anterior circulation large vessel occlusion received baseline CTP, multidelay ASL, and diffusion-weighted imaging (DWI) in succession. Multidelay ASL image was processed to reconstruct ATT, CBF without ATT correction, and CBF corrected by ATT. The consistency of hypoperfusion and ischemic penumbra volume calculated by CTP and multidelay ASL were quantified by intraclass correlation coefficient (ICC) in 2-way mixed effects, absolute agreement, and single measure. Wilcoxon signed-rank test was used to compare the difference in penumbra volume between CTP, corrected ASL, and uncorrected ASL. Thirty patients were included. Hypoperfusion volume based on multidelay ASL with different thresholds were 117.95 (87.77-151.49) mL for corrected relative CBF<40%, 130.29 (85.99-249.37) mL for CBF corrected by ATT<20 mL·100g-1·min-1, no statistical difference (P>0.05) compared with the volume of CTP, and consistency was almost excellent (ICC, 0.91) and substantial consistent (ICC, 0.727). The volumes of ischemic penumbra were 91.00 (42.68-125.27) mL for corrected relative CBF<40%-DWI, 108.94 (62.03-150.86) mL for CBF corrected by ATT<20 mL·100 g-1·min-1-DWI, which showed no statistical difference compared with the penumbra volume of CTP (P>0.05). The consistency was excellent (ICC, 0.822) and moderate (ICC, 0.501), respectively. The volume of uncorrected relative CBF <40%-DWI was 209.57 (123.21-292.45) mL, statistically larger than corrected relative CBF <40%-DWI (P<0.001) and CTP (P<0.001). The volume of uncorrected CBF<20 mL·100g-1·min-1-DWI was 186.23 (86.56-298.22) mL, statistically larger than CBF corrected by ATT<20 mL·100g-1·min-1-DWI (P<0.001) and CTP(P<0.001). The volume of ischemic penumbra determined by CBF/DWI mismatch based on multidelay ASL is consistent with CTP. The penumbra volume calculated by CBF adjusted by ATT is more accurate.

Effects of fitting methods, high b-values and image quality on diffusion and perfusion quantification and reproducibility in the calf

PurposesThe study aimed to optimize diffusion-weighted imaging (DWI) image acquisition and analysis protocols in calf muscles by investigating the effects of different model-fitting methods, image quality, and use of high b-value and constraints on parameters of interest (POIs). The optimized modeling methods were used to select the optimal combinations of b-values, which will allow shorter acquisition time while achieving the same reliability as that obtained using 16 b-values. MethodsTest-retest baseline and high-quality DWI images of ten healthy volunteers were acquired on a 3T MR scanner, using 16 b-values, including a high b-value of 1200 s/mm2, and structural T1-weighted images for calf muscle delineation. Three and six different fitting methods were used to derive ADC from monoexponential (ME) model and Dd, fp, and Dp from intravoxel incoherent motion (IVIM) model, with or without the high b-value. The optimized ME and IVIM models were then used to determine the optimal combinations of b-values, obtainable with the least number of b-values, using the selection criteria of coefficient of variance (CV) ≤10% for all POIs. ResultsThe find minimum multivariate algorithm was more flexible and yielded smaller fitting errors. The 2-steps fitting method, with fixed Dd, performed the best for IVIM model. The inclusion of high b-value reduced outliers, while constraints improved 2-steps fitting only. ConclusionsThe optimal numbers of b-values for ME and IVIM models were nine and six b-values respectively. Test-retest reliability analyses showed that only ADC and Dd were reliable for calf diffusion evaluation, with CVs of 7.22% and 4.09%.

Abstract WP125: Relationships Of Hemoglobin With Ischemic Lesions After Intracerebral Hemorrhage

Introduction: Hemoglobin concentrations and diffusion weighted imaging (DWI) lesions are separately known to be associated with poor intracerebral hemorrhage (ICH) outcomes. Though hemoglobin concentrations are related to both hypoxia and thrombosis at their extremes, it is unknown whether hemoglobin concentrations relate to DWI lesions after ICH. Methods: Spontaneous, supratentorial ICH patients with available baseline hemoglobin and hospitalized MRI data enrolled into a multicenter cohort study between 2010-2016 were analyzed. Baseline hemoglobin was assessed as both a continuous variable (g/dL) and categorical variable (&lt;11, 11 to &lt;13, 13 to &lt;15, &gt;/=15 g/dL). Primary analyses assessed relationships of baseline hemoglobin with MRI DWI lesions. Secondary analyses assessed independent relationships of hemoglobin and DWI lesions with poor 3-month outcomes (modified Rankin Scale [mRS] 4-6). Separate multivariable regression models assessed these relationships after adjusting for relevant covariates. Results: Of 917 ICH patients analyzed, the mean baseline hemoglobin was 13.8 g/dL (+/-1.9), 60% were deep ICH, and DWI lesions were identified in 27% of the cohort. In our primary analyses, increased hemoglobin, defined as a continuous variable, was associated with DWI lesions (adjusted OR 1.21, 95% CI: 1.07-1.37) after adjusting for sex, race, ICH severity, time to MRI, and blood pressure treatment change. In secondary analyses, DWI lesions were associated with poor 3-month outcomes (adjusted OR 1.83, 95% CI: 1.24-2.69) adjusting for similar covariates. We identified associations of low hemoglobin categories, when referenced to hemoglobin 13 to &lt;15 g/dL, with poor outcomes (&lt;11 g/dL: adjusted OR 1.99, 95% CI: 1.05-3.79; 11 to &lt;13 g/dL: adjusted OR 1.62, 95% CI: 1.04-2.52). Effect estimates of high hemoglobin (&gt;/=15 g/dL) with poor outcomes were smaller and imprecise (adjusted OR 1.39, 95% CI: 0.89-2.17). Conclusions: We identified novel relationships between higher baseline hemoglobin concentrations and DWI lesions in ICH patients. Further studies are required to clarify the role of hemoglobin concentrations on both cerebral small vessel disease pathophysiology and ICH outcomes.

Diffusion kurtosis imaging in patients with tissue-negative transient ischemic attack.

Approximately 50-60% of patients with a clinical transient ischemic attack (TIA) do not have diffusion-weighted imaging (DWI) evidence of cerebral ischemia. The purpose of this study was to assess the added diagnostic value of diffusion kurtosis imaging (DKI) in the evaluation of patients with TIA who have normal DWI findings. From September 2014 to May 2017, a total of 179 consecutive patients with suspected TIA were eligible for enrollment in our study. The inclusion criteria were a confirmed diagnosis of TIA confirmed by a stroke neurologist, MRI (including DWI and DKI) within 24 h after symptom onset, no stroke history, and no DWI lesion. A follow-up DWI was performed to establish stroke recurrence within a period of 90 days. A total of 98 patients who had no lesions on the baseline DWI were included for data analysis. Of these 98 patients, 31 (31.6%) had positive findings on the initial DKI. In 29 of the 31 (93.5%) patients, the location of the abnormality observed on DKI was consistent with the clinical symptoms. During the 90-day follow-up period, 14 (14.3%) patients developed recurrent stroke. The prevalence of recurrent stroke was higher in the DKI-positive group than in the DKI-negative group (29.0% vs. 7.5%, p = 0.01). A comparison between the patients with and without recurrent stroke showed that an abnormality on the baseline DKI was associated with stroke recurrence. Furthermore, 8 of the 9 stroke patients in the DKI-positive group developed a new ischemic lesion in the artery territory corresponding to the initial DKI abnormality. The new findings suggest the predictive value of DKI on the recurrence of stroke in the patients with TIA who have negative findings on conventional DWI.

Local ablation of hepatocellular carcinoma by interstitial brachytherapy: prediction of outcome by diffusion-weighted imaging.

Interstitial brachytherapy (iBT) has become a viable treatment option in the therapy of early and intermediate stage hepatocellular carcinoma (HCC). Prognostic imaging tools to predict patient outcome are missing. To assess the predictive value of baseline diffusion-weighted imaging in HCC before iBT with regard to local tumor control and overall survival (OS). We retrospectively identified 107 patients who underwent iBT for HCC from 2011 to 2018 from our database. Apparent diffusion coefficient (ADC) values for each treated lesion were analyzed in region of interest measurements. Additionally, explorative combined ratios adjusting total measured lesion area and mean measured lesion area per patient by ADC values were calculated. Measurements underwent a univariate and multivariate Cox regression analysis. The log rank test was then used to verify prognostic cutoff levels for median survival time. A total of 189 lesions in 81 patients were measured. Median survival of patients was 46.0 months. Neither ADC parameter was indicative of local tumor control. Lesion size >5 cm was associated with lower local tumor control (hazard ratio [HR]=4.292, 95% confidence interval [CI]=1.285-14.331; P = 0.018). Average measured lesion area divided by ADCmin (ADCarea mean, min) was identified to independently predict OS (HR=1.994, 95% CI=1.172-3.392; P = 0.011). A cutoff based on the variable's median (0.29 × 10-4 AU) identified patients with poor outcome (OS 36 vs. 61 months) for lower ADCarea mean, min values as verified by the log-rank test (P = 0.040). Pre-treatment ADCarea mean, min may serve as an independent predictor of OS in patients with HCC undergoing iBT.

Impact of baseline gadoxetic acid-enhanced liver magnetic resonance and diffusion-weighted imaging in resectable colorectal liver metastases: A prospective, monocentric study

BackgroundLiver magnetic resonance imaging (MRI) utilizing hepatocyte-specific contrast agent and diffusion-weighted imaging (DWI) is currently used to properly stage colorectal liver metastases (CRLM) in patients candidate to liver surgery. However, the added value of liver MRI in choosing the treatment strategy in resectable CRLM over computed tomography (CT)-scan is not clear. Patients and methodsThis is a prospective monocentric collection of consecutive cases of patients with CRLM conceived with the aim to assess the added value of liver MRI in changing the initial treatment strategy planned according to CT-scan. Potential changes in the initially planned strategy were defined as: - from upfront surgery to perioperative chemotherapy (fluoropyrimidine and oxaliplatin) - from upfront surgery to first-line systemic therapy (doublet or triplet plus a biological agent) - from perioperative chemotherapy to first-line systemic therapy.Hypothesising that MRI may induce a change in the choice of the treatment strategy in the 20% of cases (alternative hypothesis), against a null hypothesis of 5%, with one-tailed alpha and beta errors of 0.05 and 0.20 respectively, 27 patients were needed. The added value of liver MRI would have been considered clinically meaningful if at least 4 changes in the treatment strategy were observed. ResultsAmong 27 enrolled patients, upfront surgery and perioperative chemotherapy strategies were chosen in 17 (63%) and 10 (37%) cases, respectively, based on CT-scan. After liver MRI, additional liver lesions were found in 8 patients (30%) and the initial strategy was changed in 7 patients (26%) (4 initially deemed candidate to upfront surgery and 3 initially sent to perioperative chemotherapy) that were treated with first-line systemic therapy. ConclusionsOur results support the indication of the current guidelines on the routine use of liver MRI in the initial workup of patients with resectable CRLM with an MRI-driven changes of initial treatment plan in a relevant percentage of cases.

Distribution and prognosis of acute ischaemic stroke with negative diffusion-weighted imaging

Background and purposeTo examine the distribution and prognosis among patients with diffusion-weighted imaging (DWI)-negative acute ischaemic stroke (AIS) and explore the differences between mild (National Institute of Health Stroke Scale...

Cerebral Microbleeds With Atrial Fibrillation After Ablation Therapy.

BackgroundThe prevalence of cerebral microbleeds (CMBs) is significantly higher in patients with atrial fibrillation (AF) than in those without AF. CMBs in patients with AF have been reported to be primarily of the lobar type, but the exact cause of this remains unknown. We investigated the possibility that hemorrhagic transformation of embolic microinfarction can account for de novo lobar CMBs.MethodsA total of 101 patients who underwent ablation therapy for AF were prospectively registered, and 72 patients completed the assessment with MRI 6 months after catheter ablation. Brain MRI, including diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI), were examined at 1–3 days (baseline) and 6 months after catheter ablation. We quantitatively evaluated the spatial and temporal distribution of embolic microinfarctions and de novo CMBs.ResultsOf the 101 patients, 68 were enrolled in this study. Fifty-nine patients (86.8%) showed embolic microinfarctions on baseline DWI immediately after catheter ablation. There were 137 CMBs in SWI, and 96 CMBs were of the lobar type. Six months later, there were 208 CMBs, including 71 de novo CMBs, and 60 of 71 (84.5%) were of the lobar type. Of the 71 de novo CMBs, 56 (78.9%) corresponded to the location of previous embolic microinfarctions found on baseline DWI. The platelet count was significantly lower and hematocrit/hemoglobin and Fazekas score were higher in the group with de novo CMBs than in the group without de novo CMBs.ConclusionDe novo CMBs frequently appeared after catheter ablation therapy. Our results suggest that embolic microinfarction can cause lobar CMBs.

Abstract 8: Hypoperfusion Lesion And Target Mismatch Prediction In Acute Ischemic Stroke From Baseline Mr Diffusion Imaging Using A 3d Convolutional Neural Network

Purpose: Perfusion imaging assesses target mismatch but requires contrast and processing software. Clinical/diffusion mismatch can miss cases that have target mismatch and could benefit from thrombectomy. We explored whether a neural network can predict hypoperfusion and identify target mismatch from diffusion-weighted imaging (DWI) and clinical information alone. Methods: Acute ischemic stroke cases with baseline MR perfusion and DWI were included from two multi-center trials and one registry for model development and a separate randomized trial for external validation. MR perfusion images were processed by RAPID, which segments Tmax lesion (Tmax≥6s) and the ischemic core lesion (apparent diffusion coefficient [ADC]≤ 620). A 3D U-Net was trained using baseline DWI, ADC, NIH stroke scale, and side of stroke as input, and the union of Tmax and ischemic core segmentation as the ground truth. 5-fold cross-validation was performed for model development cohort. Model performance was evaluated by Dice score coefficient (DSC) and volume difference. Sensitivity and specificity of model target mismatch and clinical/diffusion mismatch criteria from the DAWN were compared, using the DEFUSE 3 target mismatch as reference. Results: 413 patients were included for model development and 46 for external validation. In model development and external validation cohort, the model achieved median DSC of 0.61 (IQR 0.45, 0.71) and 0.62 (IQR 0.53, 0.72); and volume difference of 3 ml (IQR -37, 41) and 7 ml (IQR -24, 32), respectively. Compared to the clinical/diffusion mismatch approach, the model identified target mismatch with a sensitivity of 89.5% vs 49.3%, a specificity of 77.5% vs 89.2% in the model development cohort, and a sensitivity of 95.6% vs 41.3% in external validation cohort. Conclusion: A 3D U-Net can predict hypoperfusion lesions from baseline DWI and clinical information, with more sensitive classification of target mismatch than clinical/diffusion mismatch.

Collateral estimation by susceptibility-weighted imaging and prediction of functional outcomes after acute anterior circulation ischemic stroke

To determine the value of susceptibility-weighted imaging (SWI) for collateral estimation and for predicting functional outcomes after acute ischemic stroke. To identify independent predictors of favorable functional outcomes, age, sex, risk factors, baseline National Institutes of Health Stroke Scale (NIHSS) score, baseline diffusion-weighted imaging (DWI) lesion volume, site of steno-occlusion, SWI collateral grade, mode of treatment, and successful reperfusion were evaluated by multiple logistic regression analyses. A total of 152 participants were evaluated. A younger age (adjusted odds ratio (aOR), 0.42; 95% confidence interval (CI) 0.34 to 0.77; P < 0.001), a lower baseline NIHSS score (aOR 0.90; 95% CI 0.82 to 0.98; P = 0.02), a smaller baseline DWI lesion volume (aOR 0.83; 95% CI 0.73 to 0.96; P = 0.01), an intermediate collateral grade (aOR 9.49; 95% CI 1.36 to 66.38; P = 0.02), a good collateral grade (aOR 6.22; 95% CI 1.16 to 33.24; P = 0.03), and successful reperfusion (aOR 5.84; 95% CI 2.08 to 16.42; P = 0.001) were independently associated with a favorable functional outcome. There was a linear association between the SWI collateral grades and functional outcome (P = 0.008). Collateral estimation using the prominent vessel sign on SWI is clinically reliable, as it has prognostic value.

Predicting Imaging Outcomes in Acute Stroke Therapy—Comparison of Magnetic Resonance Imaging and Computed Tomography

Abstract Background Imaging of acute stroke patients in emergency settings is critical for treatment decisions. Most commonly, CT with CTA is used worldwide for acute stroke. However, MRI may be advantageous in certain settings. With advancements in endovascular clot retrieval techniques, there is a need to identify and use the best possible imaging for the diagnosis and outcome prediction of hyperacute stroke. Methods This mixed retrospective and prospective observational study was conducted over 2 years in patients who underwent reperfusion therapies. Patients were included in this study if they had a baseline as well as follow-up noncontrast CT and diffusion-weighted imaging (DWI) MRI. We compared them for estimating final infarct size and outcomes after reperfusion therapy. Results A total of 86 patients were included in the study. Baseline DWI found new infarcts in 33 patients compared to baseline CT. Sensitivity and specificity of CT and DWI in predicting the final infarct size was 75.3% and 76.9% and 97.2% and 92.3%, respectively. A positive correlation of 51.2% and 84.4% was noted between b-CT Alberta stroke programme early CT score (ASPECTS) and b-DWI with 72 hours DWI ASPECTS, respectively (p &lt; 0.001). The positive predictive value of CT was 94.8% and DWI was 98.6%. None of the patients had reversible hyperintensities in the follow-up DWI. Conclusion MRI is more sensitive and specific than noncontrast CT in predicting final infarct volume. It predicts final outcomes better and could be an alternative if available in acute stroke settings.

Role of Apparent Diffusion Coefficient Gradient Within Diffusion Lesions in Outcomes of Large Stroke After Thrombectomy.

The outcome of endovascular treatment in stroke patients with a large ischemic core is not always satisfactory. We evaluated whether the severity of baseline diffusion-weighted imaging abnormalities, as assessed by different apparent diffusion coefficient (ADC) thresholds, correlates with the clinical outcome in these patients after successful endovascular treatment. In 82 consecutive patients with a large vessel occlusion in the anterior circulation admitted ≤24 hours after onset, a baseline diffusion lesion volume (ADC ≤620×10-6 mm2/s [ADC620]) ≥50 mL and successful recanalization by endovascular treatment were retrospectively investigated. Lesion volumes of 3 ADC thresholds (ADC620, ADC ≤520×10-6 mm2/s [ADC520], and ADC ≤540×10-6 mm2/s [ADC540]) were measured using an automated Olea software program. The performance of the ADC520/ADC620 and ADC540/ADC620 ratios in predicting the functional outcome was assessed by receiver operating characteristic curve analysis. The ADC ratio with optimal threshold showing better receiver operating characteristic performance was dichotomized at its median value into low versus high subgroup and its association with the outcome subsequently evaluated in a multivariable logistic regression model. The median baseline diffusion lesion volume was 80.8 mL (interquartile range, 64.4-105.4). A good functional outcome (modified Rankin Scale score, ≤2) was achieved in 35 patients (42.7%). The optimal threshold for predicting the functional outcome was identified as ADC540/ADC620 (area under the curve, 0.833) and dichotomized at 0.674. After adjusting for age, baseline National Institutes of Health Stroke Scale score, intravenous tissue-type plasminogen activator, baseline diffusion lesion volume, and onset-to-recanalization time, a low ADC540/ADC620 was independently associated with a good functional outcome (adjusted odds ratio, 10.72 [95% CI, 3.06-37.50]; P<0.001). A low ADC540/ADC620, which may reflect less severe ischemic stress inside a diffusion lesion, may help to identify patients who would benefit from endovascular treatment despite having a large ischemic core.

Apparent diffusion coefficients (ADC) in response assessment of transarterial radioembolization (TARE) for liver metastases of neuroendocrine tumors (NET): a feasibility study.

BackgroundIn patients with hepatic neuroendocrine tumors (NETs) locoregional therapies such as transarterial radioembolization (TARE) are increasingly applied. Response evaluation remains challenging and previous studies assessing response with diffusion-weighted imaging (DWI) have been inconclusive.PurposeTo perform a feasibility study to evaluate if response assessment with quantitative apparent diffusion coefficient (ADC) in patients with liver metastases of NETs after TARE will be possible.Material and MethodsRetrospectively, 43 patients with 120 target lesions who obtained abdominal magnetic resonance imaging (MRI) with DWI 39±28 days before and 74±46 days after TARE were included. Intralesional ADC (ADCmin, ADCmax, and ADCmean) were measured for a maximum number of three lesions per patient on baseline and post-interventional DWI. Tumor response was categorized according to RECIST 1.1 and mRECIST.ResultsTARE resulted in partial remission (PR) in 23% (63%), in stable disease (SD) in 73% (23%), in progressive disease (PD) in 5% (7%) and in complete response (CR) in 0% (1%) according to RECIST 1.1 (mRECIST, respectively). ADC values increased significantly (P<0.005) after TARE in the PR group whereas there was no significant change in the PD group. Post-therapeutic ADC values of SD lesions increased significantly when evaluated by RECIST 1.1 but not if evaluated by mRECIST. Percentual changes of ADCmean values were slightly higher for responders compared to non-responders (P<0.05).ConclusionADC values seem to represent an additional marker for treatment response evaluation after TARE in patients with secondary hepatic NET. A conclusive study seems feasible though patient-based evaluation and overall survival and progression free survival as alternate primary endpoints should be considered.

Prognostic value of tumoral and peritumoral magnetic resonance parameters in osteosarcoma patients for monitoring chemotherapy response

ObjectivesTo evaluate parameters of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as early imaging indicators of tumor histologic response to pre-operative neoadjuvant chemotherapy and as probable prognostic factors for event-free survival (EFS) and overall survival in osteosarcoma (OS) in both tumoral and peritumoral areas.MethodsThirty-four OS patients who received three courses of neoadjuvant chemotherapy followed by surgery during 2014–2018 were enrolled in this study. All patients underwent baseline and post-chemotherapy DWI and DCE-MRI. Lesion region was defined as the tumoral area and peritumoral area. Parameters of apparent diffusion coefficient, capacity transfer constant (Ktrans), elimination rate constant, extravascular extracellular space volume ratio (Ve), and initial area under the curve as well as corresponding differences between pre- and post-chemotherapy in lesion regions were evaluated. Receiver operating characteristic analysis was used to evaluate the diagnostic performance of these parameters. The associations of all parameters with tumor histologic response, EFS, and overall survival were also calculated.ResultsIn the tumor area, moderate evidence was found that post-Ktrans was lower in responders as compared with that in poor responders (p = 0.04, false discovery rate [FDR] corrected), and ΔKtrans exhibited significant between-groups differences (p = 0.04, Bonferroni corrected; or p = 0.006, FDR corrected). Weak evidence for the between-groups difference was found in the Ve in the peritumoral area (p = 0.025 before treatment and p = 0.021 after treatment, uncorrected). Furthermore, lower post-Ktrans in the tumoral area and lower pre-Ve in the peritumoral area were significant prognostic indicators for longer EFS (p = 0.002, p = 0.026) and overall survival (p = 0.003, p = 0.023).ConclusionsIn OS, DWI and DCE-MRI parameters in both tumoral and peritumoral areas can reflect the chemotherapy response and prognosticate EFS and overall survival.Key Points• Peritumoral MRI parameters can reflect the chemotherapy response in OS patients.• Peritumoral MRI parameters can predict EFS and overall survival in OS patients.• MRI parameters may be predictive factors for evaluating chemotherapy efficacy and EFS.

Benefit of first‐pass complete reperfusion in thrombectomy is mediated by limited infarct growth

The number of clot retrieval attempts required to achieve complete reperfusion by mechanical thrombectomy impacts functional outcome in acute ischaemic stroke (AIS). Complete reperfusion [expanded Treatment In Cerebral Infarction (eTICI) score=3] at first pass (FP), is associated with the highest rates of favorable outcome compared to complete reperfusion by multiple passes. The aim of the present study was to investigate the relationship between FP complete reperfusion and infarct growth (IG). Anterior AIS patients with baseline and 24-h diffusion-weighted magnetic resonance imaging were included from two prospective registries. IG was measured by voxel-based segmentation of initial and 24-h diffusion-weighted imaging lesions. IG and favorable 3-month modified Rankin Scale (mRS) score (≤2) were compared between patients in whom complete reperfusion (eTICI 3) was achieved with a single pass (FP group) and those for whom multiple passes were required (MP group), after matching for confounding factors. Mediation analysis was performed to examine the association between FP and 3-month mRS score, with IG as mediating variable. A total of 200 patients were included, of whom 118 (28.9%) had FP complete reperfusion. In case-control analysis, the FP group had lower IG than the MP group [8.7 (5.4-12.9) ml vs. 15.2(11-22.6) ml, respectively; P=0.03). Favorable outcome was higher in the FP population compared to a matched MP population (70.9% vs. 53.2%, respectively; P=0.04). FP compete reperfusion (eTICI 3) was independently associated with favorable outcome in multivariable regression analysis [odds ratio 1.86, 95% confidence interval (CI) 1.01-4.39; P=0.04]. The effect of complete reperfusion at FP on functional outcome was explained by limited IG in mediation analysis [indirect effect: -0.32 (95% CI -0.47 to -0.09)]. Complete reperfusion at FP is independently associated with significant decrease in IG compared to complete reperfusion by multiple attempts, explaining better functional outcomes.

Early successful reperfusion after endovascular therapy reduces malignant middle cerebral artery infarction occurrence in young patients with large diffusion-weighted imaging lesions.

Malignant middle cerebral artery infarction (MMI) is a severe complication of acute ischaemic stroke (AIS). The aim of our study was to assess whether successful reperfusion after endovascular therapy (EVT) in AIS with clinical and imaging predictors of MMI decreased its occurrence. Data were collected between January 2014 and July 2018 in a monocentric prospective AIS registry of patients treated with EVT. Patients selected were <65years old with severe anterior circulation AIS with a National Institutes of Health Stroke Scale score >15, baseline Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Score≤6 and baseline diffusion-weighted imaging lesion volume >82mL within 6h of symptom onset. Successful reperfusion was defined as a Thrombolysis in Cerebral Ischemia score≥2b. Occurrence of MMI was the primary endpoint. A total of 66 EVT-treated patients were included in our study. MMI occurred in 27 patients (41%). In unadjusted analysis, successful reperfusion was associated with fewer MMIs (31.8% vs. 65.0%; P=0.015) and with more favorable outcome at 3months (50% vs. 20%; P=0.023). In multivariate analysis, successful reperfusion was associated with an adjusted odds ratio (95% confidence intervals) of 0.35 (0.10-1.12) for MMI and 2.77 (0.84-10.43) for 3-month favorable outcome occurrence. Early successful reperfusion performed in patients with AIS with clinical and imaging predictors of MMI was associated with decreased MMI occurrence. Reperfusion status might be considered in evaluating the need for craniectomy in patients with early predictors of MMI.

Cavitation of symptomatic acute single small subcortical infarctions.

To investigate cavitation of symptomatic acute single small subcortical infarctions (SSSI). Acute SSSI were diagnosed with magnetic resonance (MR) diffusion-weighted imaging (DWI) combined with apparent diffusion coefficient (ADC) sequence on follow-up MR imaging. Cavitation of the acute SSSI was comprehensively viewed on FLAIR, T2-, and T1-weighted sequences. We enrolled 123 patients with acute SSSI. The follow-up median interval was 303 (125-390) days. The lesions of SSSI evolved into cavitation in 93 patients (75.6%), evolved into WMHs in nine patients (7.3%), and were no visible in 21 patients (17.1%). Cavitation was independently associated with larger infarct diameter on baseline DWI [odds ratio (OR), 1.250, 95% CI (1.078-1.451), P= 0.003], higher score of baseline old lacunar infarct [OR 3.44, 95% CI (1.49-7.91), P= 0.004], and lower rate of dyslipidemia [OR 0.30, 95% CI (0.10-0.76), P= 0.013]. Cavitation occurred more in the setting of small vessel diseased brain and less in the SSSI of possible atherosclerotic etiology. This suggested that the etiology of infarct was associated with cavitation after acute SSSI.