Quantitative analysis of thrombus migration before mechanical thrombectomy: Determinants and relationship with procedural and clinical outcomes.

BACKGROUND AND PURPOSE: In patients with acute ischemic stroke (AIS) and a large vessel occlusion (LVO), thrombus migration (T-Mig) is a common phenomenon before mechanical thrombectomy (MT), revealed by pre-treatment imaging. Previous works have used qualitative scales to define T-Mig. The aim of this study was to evaluate the determinants and impact of quantitatively assessed T-Mig on procedural characteristics and clinical outcome. METHODS: Consecutive patients with AIS due to LVO treated by MT at a reference academic hospital were analysed. Distance between vessel origin and beginning of the thrombus on MRI (3D-time-of-flight and/or contrast-enhanced magnetic-resonance-angiography) and digital-substracted-angiography (DSA) were measured in millimeters using a curve tool. Thrombus migration was defined quantitatively as ∆TD calculated as the difference between pre-MT-DSA and MRI thrombus location. ∆TD was rated as significant if above 5mm. RESULTS: A total of 267 patients were included (mean age 70±12 years; 46% females) were analyzed. Amongst them, 65 (24.3%) experienced any degree of T-Mig. T-Mig was found to be associated with iv-tPA administration prior to thrombectomy (ß-estimate 2.52; 95% CI [1.25-3.79]; p<0.001), fewer device passes during thrombectomy (1.22±1.31 vs 1.66±0.99; p<0.05), and shorter pre-treatment thrombi (ß-estimate -0.1millimeter; 95% CI [-0.27-0.07]; p<0.05). There was no association between T-Mig and a favourable outcome (defined by a 0-to-2 modified-Rankin-Scale at 3months, adjusted OR: 2.16 [0.93 - 5.02]; p=0.06) CONCLUSION: Thrombus migration happens in almost a fourth of our study sample, and its quantitative extent was associated with iv-tPA administration prior to MT, but not with clinical outcome.

Detection of recurrent brain tumors in children: No significant difference in sensitivity between unenhanced and contrast-enhanced MRI.

BACKGROUND: Magnetic resonance imaging (MRI) with a gadolinium injection is currently used in the follow-up of children in remission of cerebral tumors (CTs). Intracerebral gadolinium deposition has been recently reported with unknown risks. The aim of this study was to evaluate the sensitivity of unenhanced brain MRI (U-MRI) in detection of tumor recurrence. METHODS AND MATERIALS: A set of 58 U-MRIs of children in remission was retrospectively evaluated by three seniors (a neuroradiologist, a pediatric and a general radiologist) and one junior to look for any recurrence. Clinical, tumoral and imaging data were collected. The final diagnosis was anatomopathological when available, or the clinicoradiological evolution. Sensitivity, specificity, predictive values and interobserver agreement were calculated. A Fisher test and Fleiss kappa coefficient were performed. RESULTS: For the seniors, the U-MRI had a sensitivity of 81% (95% confidence interval (CI): 0.56-0.90), and a negative predictive value (NPV) of 82% (95% CI: 0.63-0.94). The U-MRI sensitivity, regardless of the observer, was not significantly different from the contrast-enhanced MRI sensitivity (86%) according to a Fisher test (p > 0.05). No significant difference in sensitivity within the subgroups was found. The interobserver agreement of seniors was good (κ = 0.68). CONCLUSION: U-MRI brain was suboptimal for 80% of patients. Three-dimensional millimetric, fluid-attenuated inversion recovery, and diffusion would constitute helpful sequences in follow-up. Further specific studies depending on each tumor type are still required to determine whether a potential abstention of gadolinium intravenous injection should be discussed for children.

Susceptibility-Diffusion Mismatch in Hyperacute Stroke: Correlation with Perfusion-Diffusion Mismatch and Clinical Outcome.

BACKGROUND: A prominent vein (PV) on susceptibility-weighted imaging (SWI) was recently proposed to be a marker of the penumbra. We aimed to compare the utility of SWI and perfusion-weighted imaging (PWI) sequences for the evaluation of the penumbra in hyperacute middle cerebral artery (MCA) stroke, and to determine whether SWI-DWI mismatch is a neuroimaging marker of clinical outcome. METHODS: A total of 149 consecutive patients with MCA stroke were prospectively enrolled. Magnetic resonance imaging (MRI) was performed within 6 hours of the onset of stroke. The ASPECTS values on diffusion-weighted imaging (DWI), PWI (delayed mean transit time), and SWI (visualization of PVs) were calculated by 2 independent raters. Correlation between PWI-ASPECTS and SWI-ASPECTS was calculated with the Pearson coefficient. Reliability of the PV rating system was calculated by an intraclass correlation coefficient (ICC). Favorable outcome was defined as a modified Rankin Scale score of 0-2 at 3 months for the 88 patients who received thrombolytic therapy. RESULTS: The ASPECTS-SWI and ASPECTS-PWI scores showed a good correlation (Pearson coefficient of .69, P <.001). The reproducibility between the findings of the junior and the senior radiologists was excellent with an ICC of .89 (confidence interval of 95% (IC95): .85-.92, P <.001). However, neither SWI-DWI mismatch nor PWI-SWI mismatch was associated with clinical outcome. CONCLUSION: SWI and PWI were complementary but not commutable for the assessment of the penumbra. Susceptibility-diffusion mismatch was not found in this study to have predictive value for stroke outcome.

Functional Outcome of Hemorrhagic Transformation after Thrombolysis for Ischemic Stroke: A Prospective Study.

BACKGROUND/AIMS: Hemorrhagic transformation (HT) is usually taken into account when symptomatic, but the role of asymptomatic HT is not well known. The aim of our study was to evaluate the link between HT after thrombolysis for ischemic stroke and functional outcome at 3 months, with particular emphasis on asymptomatic HT. METHODS: Our study was performed prospectively between June 2012 and June 2013 in the Stroke Unit of the University Hospital Center of Tours (France). All patients treated with intravenous thrombolysis were consecutively included. HT was classified on susceptibility-weighted imaging (SWI) with 3-tesla MRI at 7 ± 3 days after treatment. We evaluated functional outcome at 3 months using the modified Rankin Scale (mRS). Dependency was defined as an mRS score of ≥ 3. RESULTS: After 1 year, 128 patients had received thrombolytic therapy for ischemic stroke, of whom 90 patients underwent both 3-tesla MRI and SWI at day 7. Fifty-two had HT, including 8 symptomatic cases. At 3 months, 68% of those patients were dependent compared to 31% of patients without HT [OR 4.6 (1.9-11.4), p = 0.001]. In asymptomatic HT, the rate was 62% [OR 3.5 (1.4-8.9), p = 0.007], but did not reach significance after adjustment for stroke severity. DISCUSSION: Our study found no statistically significant effect of HT on outcome after adjustment for initial stroke severity. However, the innocuousness of HT is not certain, and only few studies have already highlighted the increased risk of dependency. Using 3-tesla MRI with SWI allows us to increase the detection rate of small hemorrhage. CONCLUSION: HT after thrombolysis is very frequent on SWI, but the initial stroke severity is an important predictor to assess the role of HT for patient outcome.