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In patients with ICA stenosis, increased peak systolic velocity is a marker of stenosis at risk of ischemic stroke. 4DFlow MRI is a reproducible technique to evaluate velocities in ICA stenosis, although it seems to underestimate velocities as compared with Doppler ultrasonography. The purpose of our study was to confirm that velocities were underestimated on a new set of data acquired with a clinical 4DFlow sequence, and to devise optimal acquisition parameters for ICA stenosis exploration based on a numerical simulation. After review board approval, 15 healthy controls and 12 patients presenting ICA stenosis were explored with Doppler ultrasonography and 4DFlow MRI. We created a 2-dimensional simulation of ICA stenosis and its corresponding 4DFlow acquisition, and compared its mean peak systolic velocity underestimation to real MRI and Doppler. We then simulated the acquisition for voxel size ranging from 0.5 to 1.25 mm and number of phases per cardiac cycle ranging from 10 to 25. On acquired data, 4DFlow MR underestimated peak systolic velocities (mean difference between Doppler and 4DFlow: − 35 cm/s), especially high velocities. With spatial and temporal resolutions equivalent to MR acquisition, our simulation yielded similar underestimation (mean difference: − 31 cm/s, P = 0.30). Simulations showed that 0.7-mm resolution and 20 phases per cardiac cycle would be necessary to record peak systolic velocities up to 250 cm/s. Higher spatial resolution can provide accurate peak systolic velocities measurement with 4DFlow MRI, thus allowing better ICA stenosis assessment. Further studies are needed to validate the proposed parameters.

In large vessel occlusion (LVO) stroke, it is unclear whether severity of ischemia is involved in early post-thrombolysis recanalization over and above thrombus site and length. Here we assessed the relationships between perfusion parameters and early recanalization following intravenous thrombolysis administration in LVO patients. From a multicenter registry, we identified 218 thrombolysed LVO patients referred for thrombectomy with both (i) pre-thrombolysis MRI, including diffusion-weighted imaging (DWI), T2*-imaging, MR-angiography and dynamic susceptibility-contrast perfusion-weighted imaging (PWI); and (ii) evaluation of recanalization on first angiographic run or non-invasive imaging ≤ 3 h from thrombolysis start. Infarct core volume on DWI, PWI-DWI mismatch volume and hypoperfusion intensity ratio (HIR; defined as Tmax ≥ 10 s volume/ Tmax ≥ 6 s volume, low HIR indicating milder hypoperfusion) were determined using a commercially available software. Early recanalization occurred in 34 (16%) patients, and multivariable analysis was associated with lower HIR ( P = 0.006), shorter thrombus on T2*-imaging ( P

Surgical resection of gliomas involving eloquent brain areas must be maximal in order to improve patients' survival, and safe to prevent postoperative impairments. Therefore, the precise spatial relationship between the lesion and eloquent brain areas needs to be established. Functional magnetic resonance imaging and diffusion tensor imaging are robust methods with increasing indications in neurosurgery for past decade. The aim of this review article is not only to pinpoint the major limitations of these methods in order to avoid erroneous conclusions, but also to detail practical aspects associated with the main paradigms routinely used in functional magnetic resonance imaging, and to discuss recent validation of functional magnetic resonance imaging and diffusion tensor imaging results with direct electrical stimulation during awake surgery.

Background and Purpose— In acute stroke patients with large vessel occlusion, the goal of intravenous thrombolysis (IVT) is to achieve early recanalization (ER). Apart from occlusion site and thrombus length, predictors of early post-IVT recanalization are poorly known. Better collaterals might also facilitate ER, for instance, by improving delivery of the thrombolytic agent to both ends of the thrombus. In this proof-of-concept study, we tested the hypothesis that good collaterals independently predict post-IVT recanalization before thrombectomy. Methods— Patients from the registries of 6 French stroke centers with the following criteria were included: (1) acute stroke with large vessel occlusion treated with IVT and referred for thrombectomy between May 2015 and March 2017; (2) pre-IVT brain magnetic resonance imaging, including diffusion-weighted imaging, T2*, MR angiography, and dynamic susceptibility contrast perfusion-weighted imaging; and (3) ER evaluated ≤3 hours from IVT start on either first angiographic run or noninvasive imaging. A collateral flow map derived from perfusion-weighted imaging source data was automatically generated, replicating a previously validated method. Thrombus length was measured on T2*-based susceptibility vessel sign. Results— Of 224 eligible patients, 37 (16%) experienced ER. ER occurred in 10 of 83 (12%), 17 of 116 (15%), and 10 of 25 (40%) patients with poor/moderate, good, and excellent collaterals, respectively. In multivariable analysis, better collaterals were independently associated with ER ( P =0.029), together with shorter thrombus ( P P =0.010). Conclusions— In our sample of patients with stroke imaged with perfusion-weighted imaging before IVT and intended for thrombectomy, better collaterals were independently associated with post-IVT recanalization, supporting our hypothesis. These findings strengthen the idea that advanced imaging may play a key role for personalized medicine in identifying patients with large vessel occlusion most likely to benefit from IVT in the thrombectomy era.

Introduction: In large vessel occlusion (LVO) stroke, it is unclear whether severity of ischemia is involved in early post-intravenous thrombolysis (IVT) recanalization over and above thrombus site and length. Here we assessed the relationships between perfusion parameters and early recanalization following IVT administration in LVO patients. Methods: From a multicentre registry, 218 thrombolysed LVO patients referred for thrombectomy since May 2015 with both i) pre-IVT MRI, including diffusion-weighted imaging (DWI), T2* imaging, MR-angiography and dynamic susceptibility-contrast perfusion-weighted imaging (PWI); and ii) recanalization evaluated on first angiographic run or non-invasive imaging ≤3hrs from IVT start, were identified. Infarct core volume on DWI, PWI-DWI mismatch volume and Hypoperfusion Intensity Ratio (HIR; defined as the proportion of Tmax>6s volume with Tmax>10sec), a validated index of hypoperfusion severity, were determined using commercially available software. Results: Early recanalization occurred in 34 (16%) patients, and was independently associated with lower HIR ( P =0.006), shorter thrombus on T2* imaging ( P P= 0.006). DWI lesion volume and PWI-DWI mismatch volume both had significant univariable association with recanalization but were not retained in the multivariable model. In addition, there was a significant interaction between thrombus length and HIR such that the effect of lower HIR on recanalization was stronger for smaller thrombi. Conclusion: This study disclosed a novel, independent association between milder hypoperfusion severity, as assessed by the HIR, and early post-IVT recanalization. Perfusion imaging may help to identify LVO patients most likely to benefit from IVT before thrombectomy.

Background Tumor location is a main prognostic parameter in patients with glioblastoma. Probabilistic MRI-based brain atlases specifying the probability of tumor location associated with important demographic, clinical, histomolecular, and management data are lacking for isocitrate dehydrogenase (IDH) wild-type glioblastomas. Purpose To correlate glioblastoma location with clinical phenotype, surgical management, and outcomes by using a probabilistic analysis in a three-dimensional (3D) MRI-based atlas. Materials and Methods This retrospective study included all adults surgically treated for newly diagnosed IDH wild-type supratentorial glioblastoma in a tertiary adult surgical neuro-oncology center (2006-2016). Semiautomated tumor segmentation and spatial normalization procedures to build a 3D MRI-based atlas were validated. The authors performed probabilistic analyses by using voxel-based lesion symptom mapping technology. The Liebermeister test was used for binary data, and the generalized linear model was used for continuous data. Results A total of 392 patients (mean age, 61 years ± 13; 233 men) were evaluated. The authors identified the preferential location of glioblastomas according to subventricular zone, age, sex, clinical presentation, revised Radiation Therapy Oncology Group-Recursive Partitioning Analysis class, Karnofsky performance status, O6-methylguanine DNA methyltransferase promoter methylation status, surgical management, and survival. The superficial location distant from the eloquent area was more likely associated with a preserved functional status at diagnosis (348 of 392 patients [89%], P < .05), a large surgical resection (173 of 392 patients [44%], P < .05), and prolonged overall survival (163 of 334 patients [49%], P < .05). In contrast, deep location and location within eloquent brain areas were more likely associated with an impaired functional status at diagnosis (44 of 392 patients [11%], P < .05), a neurologic deficit (282 of 392 patients [72%], P < .05), treatment with biopsy only (183 of 392 patients [47%], P < .05), and shortened overall survival (171 of 334 patients [51%], P < .05). Conclusion The authors identified the preferential location of isocitrate dehydrogenase wild-type glioblastomas according to parameters of interest and provided an image-based integration of multimodal information impacting survival results. This suggests the role of glioblastoma location as a surrogate and multimodal parameter integrating several known prognostic factors. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Huang in this issue.

Background and Purpose— Rapid and reliable assessment of the perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) mismatch is required to promote its wider application in both acute stroke clinical routine and trials. We tested whether an evaluation based on the Alberta Stroke Program Early CT Score (ASPECTS) reliably identifies the PWI/DWI mismatch. Methods— A total of 232 consecutive patients with acute middle cerebral artery stroke who underwent pretreatment magnetic resonance imaging (PWI and DWI) were retrospectively evaluated. PWI-ASPECTS and DWI-ASPECTS were determined blind from manually segmented PWI and DWI volumes. Mismatch-ASPECTS was defined as the difference between PWI-ASPECTS and DWI-ASPECTS (a high score indicates a large mismatch). We determined the mismatch-ASPECTS cutoff that best identified the volumetric mismatch, defined as Volume T max>6s /Volume DWI ≥1.8, a volume difference≥15 mL, and a Volume DWI Results— Inter-reader agreement was almost perfect for PWI-ASPECTS (κ=0.95 [95% confidence interval, 0.90–1]), and DWI-ASPECTS (κ=0.96 [95% confidence interval, 0.91–1]). There were strong negative correlations between volumetric and ASPECTS-based assessments of DWI lesions (ρ=−0.84, P P Conclusions— The mismatch-ASPECTS method can detect a true mismatch in patients with acute middle cerebral artery stroke. It could be used for rapid screening of patients with eligible mismatch, in centers not equipped with ultrafast postprocessing software.

Background Infarct growth (IG) is used as surrogate end-point in therapeutic trials. For practical reasons, infarct growth is commonly assessed using simple subtraction of acute from follow-up diffusion-weighted imaging (DWI) lesion volumes. However, the volume subtraction method will underestimate true infarct growth in case of diffusion-weighted imaging lesion reversal. Aim To measure the size of the difference between true infarct growth on voxel-based coregistration and infarct growth approximated with simple volume subtraction. Methods We retrospectively analyzed 322 consecutive stroke patients (median (IQR) age: 70 years (57–80), National Institute of Health Stroke Score at admission 14 (8–19)), who underwent a magnetic resonance imaging before (DWI1) and ≈24 h (DWI2) after IV-thrombolysis. IGvoxel-based was defined as the volume of signal changes on DWI2 that did not overlap with that on coregistered DWI1. This was compared with simply subtracting DWI1 from DWI2 lesion volume (IGsubtracted). We also compared these two metrics for the prediction of three-month unfavorable outcome (mRS ≥ 2) using c-statistics of multivariable models, adjusted for age, and National Institute of Health Stroke Score. Results Infarct growth volume metrics were strongly correlated (ρ = 0.94), but IGsubtracted substantially underestimated IGvoxel-based (median (IQR): 9.52 (0.23–38.9) vs. 16.98 (4.4–45.4) mL). Of the 75 patients with shrinking or stable diffusion-weighted imaging lesion using volume subtraction, IGvoxel-based was ≥5 mL in 20 (27% of the subset, 6.2% of the whole population). Moreover, IGvoxel-based better predicted unfavorable outcome than IGsubtracted (c-statistics = 0.86 (95% CI, 0.82–0.90) vs. 0.82 (0.78–0.87), P = 0.003). Conclusion At early post-thrombolysis time points, the simple subtraction of lesion volumes masked substantial diffusion-weighted imaging lesion growth in 6.2% of patients. Although more time-consuming, the voxel-based method may impact results of trials that use infarct growth attenuation as an end-point.

Objectif La perfusion par marquage de spins arteriel (ASL) est une technique d’IRM de perfusion non invasive prometteuse. Son application dans la vasculopathie cerebrale drepanocytaire reste neanmoins limite du fait de temps de transit arteriel (TTA) allonges par le developpement de nombreuses collaterales. L’ASL avec delais post-marquage multiples (ASL multi-delais) semble prometteuse dans cette indication. Notre objectif etait de valider la technique d’ASL multi-delais pour la mesure du debit sanguin cerebral chez des patients drepanocytaires avec vasculopathie cerebrale. Methodes Une sequence ASL standard a delai unique (duree du marquage = 1500 ms, delai post-marquage = 2025 ms) et une sequence ASL multi-delais (duree du marquage = 4000 ms, 7 delais post-marquage: 2000 a 5000 ms) ont ete realisees sur une IRM 3 Tesla chez 21 patients drepanocytaires avec vasculopathie cerebrale. Une IRM de perfusion T2* a ete realisee pour evaluer la severite de la vasculopathie et identifier les regions corticales avec un Tmax normal ( 4 secondes). Les valeurs de debit sanguin cerebral relatif (DSCr), de TTA et de Tmax ont ete automatiquement extraites dans 20 regions corticales. Resultats Les valeurs de DSCr mesurees en ASL standard etaient plus faibles, correspondant a 93 %, 89 % (p Conclusion L’ASL multi-delais est une technique non invasive qui ameliore l’evaluation de la perfusion cerebrale dans la vasculopathie cerebrale drepanocytaire, en particulier dans les regions corticales avec temps de transit arteriel allonge. Cette technique pourrait eviter le recours a l’injection de produit de contraste chez les patients drepanocytaires difficiles a perfuser.

A number of training interventions have been designed to improve executive functions and inhibitory control (IC) across the lifespan. Surprisingly, no study has investigated the structural neuroplasticity induced by IC training from childhood to late adolescence, a developmental period characterized by IC efficiency improvement and protracted maturation of prefrontal cortex (PFC) subregions involved in IC. The aim of the present study was to investigate the behavioral and structural changes induced by a 5-week computerized and adaptive IC training in school-aged children (10-year-olds) and in adolescents (16-year-olds). Sixty-four children and 59 adolescents were randomly assigned to an IC (i.e. Color-Word Stroop and Stop-Signal tasks) or an active control (AC) (knowledge- and vocabulary-based tasks) training group. In the pre- and posttraining sessions, participants performed the Color-Word Stroop and Stop-signal tasks, and an anatomical resonance imaging (MRI) was acquired for each of them. Children's IC efficiency improved from the pre- to the posttraining session in boys but not in girls. In adolescents, IC efficiency did not improve after IC training. Similar to the neuroplastic mechanisms observed during brain maturation, we observed IC training-related changes in cortical thickness and cortical surface area in several PFC subregions (e.g. the pars opercularis, triangularis, and orbitalis of the inferior frontal gyri) that were age- and gender-specific. Because no correction for multiple comparisons was applied, the results of our study provide only preliminary evidence of the complex structural neuroplastic mechanisms at the root of behavioral changes in IC efficiency from pre- to posttraining in school-aged children and adolescents.

Neuroimaging is critical in the evaluation of patients with transient ischemic attack (TIA) and MRI is the recommended modality to image an ischemic lesion. The presence of a diffusion (DWI) lesion in a patient with transient neurological symptoms confirms the vascular origin of the deficit and is predictive of a high risk of stroke. Refinement of MR studies including high resolution DWI and perfusion imaging using either MRI or CT further improve the detection of ischemic lesions. Rapid etiological work-up includes non-invasive imaging of cervical and intracranial arteries to search for symptomatic stenosis/occlusion associated with an increased risk of stroke.

Because of its excellent sensitivity and specificity to diagnose arterial ischemic stroke (AIS) in the acute phase, MRI answers the main questions to guide treatment in “candidates” for thrombolysis. It lasts less than ten minutes, can confirm the diagnosis of AIS and distinguish it from hematomas and other “stroke mimics”. It can identify the ischemic penumbra (perfusion-diffusion mismatch), determine the site of occlusion and provide prognostic information to adapt treatment in some cases in which the indications are poorly defined. In light of the most recent scientific findings, MRI can guide the treatment turning it into the investigation of choice in “candidates” for thrombolysis.

Resume Du fait de son excellente sensibilite et specificite pour le diagnostic d’accident vasculaire ischemique (AIC) arteriel a la phase aigue, l’IRM repond aux questions essentielles pour guider le traitement chez les « candidats » a la thrombolyse. Realisable en moins de 10 minutes, elle permet de poser le diagnostic positif d’AIC et de le distinguer des hematomes et de certains stroke mimics. Elle permet d’identifier la penombre ischemique (mismatch perfusion–diffusion), de determiner le site d’occlusion et fournit des elements pronostiques pour adapter le traitement dans certains cas ou les indications ne sont pas clairement definies. L’IRM, a la lumiere des donnees scientifiques les plus recentes, permet de guider l’indication therapeutique, ce qui en fait l’examen de choix chez les « candidats » a la thrombolyse.

Background and Purpose— Arterial wall enhancement on vessel wall MRI was described in intracranial inflammatory arterial disease. We hypothesized that circumferential aneurysmal wall enhancement (CAWE) could be an indirect marker of aneurysmal wall inflammation and, therefore, would be more frequent in unstable (ruptured, symptomatic, or undergoing morphological modification) than in stable (incidental and nonevolving) intracranial aneurysms. Methods— We prospectively performed vessel wall MRI in patients with stable or unstable intracranial aneurysms. Two readers independently had to determine whether a CAWE was present. Results— We included 87 patients harboring 108 aneurysms. Interreader and intrareader agreement for CAWE was excellent (κ=0.85; 95% confidence interval, 0.75–0.95 and κ=0.90; 95% confidence interval, 0.83–0.98, respectively). A CAWE was significantly more frequently seen in unstable than in stable aneurysms (27/31, 87% versus 22/77, 28.5%, respectively; P P =0.0002). Conclusions— CAWE was more frequently observed in unstable intracranial aneurysms and may be used as a surrogate of inflammatory activity in the aneurysmal wall.

Resume Le guide du bon usage des examens d’imagerie medicale de la Societe francaise de radiologie recommande l’IRM comme examen de premiere intention pour l’exploration des accidents vasculaires cerebraux. Cette presentation illustrera les principales images pieges en cas de suspicion de pathologie vasculaire cerebrale et expliquera les astuces techniques ou connaissances necessaires pour un compte-rendu radiologique optimal.

Triage imaging facilitates the timely recognition of acute stroke with prognostic implications. Improvement in MR acquisition speed is needed given the extreme time constraints before treatment. We compared an ultrafast Echo-Planar FLAIR sequence (EPI-FLAIR) and a conventional FLAIR sequence (cFLAIR) for their diagnostic performances and ability to estimate the age of infarction.Between June and August 2014, 125 consecutive patients (age 69±18 years, 48% men) admitted for a suspicion of acute (≤48-hrs) stroke were explored by both FLAIR sequences at 1.5-Tesla. EPI-FLAIR (15-sec) and cFLAIR (2-min and 15-sec) were compared by two readers, blinded to clinical data.EPI-FLAIR was less prone to kinetic artefacts than cFLAIR (2-3% vs. 23-49% depending on the reader, P0.001). Diagnostic concordance was excellent for both readers (к0.9). Amongst 8 hemorrhages, one subarachnoid hemorrhage presenting as a sudden deficit was missed on EPI-FLAIR sequence. Amongst 60 infarctions, cFLAIR and EPI-FLAIR were concordant in 50 (83%), while signal changes were visible on cFLAIR only in the remaining 10 (17%) cases. Amongst the 43 patients with known onset time (n=17 within 4.5hrs), FLAIR-DWI mismatch identified4.5-hrs infarction with the same sensitivity (65%) using cFLAIR and EPI-FLAIR, but the positive predictive value (PPV) was higher for cFLAIR than for EPI-FLAIR (73% vs. 50%, P=0.008).EPI-FLAIR allows a drastic reduction of acquisition time devoted to FLAIR sequence and minimizes motion artifacts. Compared with cFLAIR, it is however associated with increased risk of undiagnosed stroke mimics and lower PPV for identifying4.5-hrs infarctions.

Autobiographical memory (AM) underlies the formation and temporal continuity over time of personal identity. The few studies on sex-related differences in AM suggest that men and women adopt different cognitive or emotional strategies when retrieving AMs. However, none of the previous works has taken into account the distinction between episodic autobiographical memory (EAM), consisting in the retrieval of specific events by means of mental time travel, and semantic autobiographical memory (SAM), which stores general personal events. Thus, it remains unclear whether differences in these strategies depend on the nature of the memory content to be retrieved. In the present study we employed functional MRI to examine brain activity underlying potential sex differences in EAM and SAM retrieval focusing on the differences in strategies related to the emotional aspects of memories while controlling for basic cognitive strategies. On the behavioral level, there was no significant sex difference in memory performances or subjective feature ratings of either type of AM. Activations common to men and women during AM retrieval were observed in a typical bilateral network comprising medial and lateral temporal regions, precuneus, occipital cortex as well as prefrontal cortex. Contrast analyses revealed that there was no difference between men and women in the EAM condition. In the SAM condition, women showed an increased activity, compared to men, in the dorsal anterior cingulate cortex, inferior parietal and precentral gyrus. Overall, these findings suggest that differential neural activations reflect sex-specific strategies related to emotional aspects of AMs, particularly regarding SAM. We propose that this pattern of activation during SAM retrieval reflects the cognitive cost linked to emotion regulation strategies recruited by women compared to men. These sex-related differences have interesting implications for understanding psychiatric disorders with differential sex prevalence and in which one of key features is overgenerality in AM.

Inhibition is considered a key mechanism in schizophrenia. Short-latency intracortical inhibition (SICI) in the motor cortex is reduced in schizophrenia and is considered to reflect locally deficient γ-aminobutyric acid (GABA)-ergic modulation. However, it remains unclear how SICI is modulated during motor inhibition and how it relates to neural processing in other cortical areas. Here we studied motor inhibition Stop signal task (SST) in stabilized patients with schizophrenia (N = 28), healthy siblings (N = 21) and healthy controls (n = 31) matched in general cognitive status and educational level. Transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) were used to investigate neural correlates of motor inhibition. SST performance was similar in patients and controls. SICI was modulated by the task as expected in healthy controls and siblings but was reduced in patients with schizophrenia during inhibition despite equivalent motor inhibition performance. fMRI showed greater prefrontal and premotor activation during motor inhibition in schizophrenia. Task-related modulation of SICI was higher in subjects who showed less inhibition-related activity in pre-supplementary motor area (SMA) and cingulate motor area. An exploratory genetic analysis of selected markers of inhibition (GABRB2, GAD1, GRM1, and GRM3) did not explain task-related differences in SICI or cortical activation. In conclusion, this multimodal study provides direct evidence of a task-related deficiency in SICI modulation in schizophrenia likely reflecting deficient GABA-A related processing in motor cortex. Compensatory activation of premotor areas may explain similar motor inhibition in patients despite local deficits in intracortical processing. Task-related modulation of SICI may serve as a useful non-invasive GABAergic marker in development of therapeutic strategies in schizophrenia.

Background and Purpose— Whether to withhold recanalization treatment when the diffusion-weighted imaging (DWI) lesion exceeds a given volume is unsettled. Our aim was to assess the impact of recanalization on outcome in patients with baseline DWI lesion ≥70 mL (DWI≥70 mL) treated ≤4.5 hours from onset. We hypothesized that recanalization is beneficial in a sizeable fraction of these patients and that this is associated with a larger DWI lesion reversal. Methods— We analyzed 267 consecutive patients treated with intravenous recombinant tissue-type plasminogen activator for middle cerebral artery territory stroke in whom an occlusion was present on magnetic resonance angiography and 24-hour recanalization and 90-day clinical outcome could be assessed. After stratification relative to the 70-mL DWI lesion cut point, we calculated the odds ratio for recanalization of the primary arterial occlusive lesion (AOL score ≥2) to predict favorable outcome (modified Rankin scale score ≤2). DWI lesion reversal was compared between recanalizers with DWI≥70 mL with favorable and unfavorable outcomes. Results— Median (interquartile range) DWI lesion volume was 22 mL (10–60), and median onset time to imaging was 116 minutes (86–151). Twelve (22%) of the 54 patients with DWI≥70 mL experienced favorable outcome, of which 9 had recanalized. In patients with DWI≥70 mL, recanalization was significantly associated with favorable outcome after adjustment for age and National Institutes of Health Stroke Scale (odds ratio =4.72 [1.09–20.32]; P =0.0375). Among recanalizers with DWI≥70 mL, absolute and relative DWI reversal volumes were larger in those with favorable as compared with unfavorable outcome (18.8 mL [12.2–47.6] versus 8.5 mL [4.3–31.1]; P =0.17; and 19.6% [10.9–62.8] versus 8.7% [3.9–16.5], respectively; P =0.049). Conclusions— Patients with DWI lesion volume ≥70 mL can benefit from recanalization after intravenous recombinant tissue-type plasminogen activator. This may partly reflect a larger amount of DWI lesion reversal.

Prospective memory (PM) refers to a complex cognitive ability that underpins the delayed execution of previously formulated intentions. PM performance declines early in normal aging and this process is accentuated in Alzheimer's disease. The left frontopolar cortex (BA10) has been consistently assigned a major role in PM functioning, but whether it can be noninvasively modulated to enhance PM perfor- mance in aged people has not been addressed so far. Here, we investigated the effects of modulating left BA10 by means of theta burst stimulation (TBS), using either excitatory (intermittent TBS), inhibitory (continuous TBS) or control (vertex) TBS in healthy aged subjects. The behavioral effects were assessed using a reliable and ecological virtual reality PM task that included both event- and time-based retrievals. As compared with vertex stimulation, event-based PM performance significantly improved after excit- atory stimulation, whereas inhibitory stimulation had no significant effect. Additionally, and across the different types of stimulation, performance for congruent links between the event-based PM cue and the action to be performed was significantly better as compared with incongruent links. In conclusion, intermittent TBS might provide a relevant interventional strategy to counteract the decline of cognitive functions and memory abilities in normal aging.

International audience; PURPOSE:To compare the occurrence of several central sulcus variants and to assess the reproducibility of a sulcal pattern named the power button sign (PBS) in patients with type 2 focal cortical dysplasia (FCD2) and healthy control subjects.MATERIALS AND METHODS:The local institutional review board approved the study, and written informed consent was waived for patients and was obtained from control subjects. Four readers reviewed three-dimensional (3D) T1-weighted magnetic resonance (MR) images in 37 patients (13 with negative MR imaging findings) with histologically proven FCD2 of the central region and 44 control subjects on the basis of a visual analysis of a 3D reconstruction of cortical folds. They searched for central sulcus variations (interruptions, side branches, and connections) and for a particular sulcal pattern, namely, the interposition of a precentral sulcal segment between the central sulcus and one of its hook-shaped anterior ascending branches (ie, PBS). Inter- and intraobserver reliability, specificity, and sensitivity were calculated.RESULTS:The central sulcus showed a greater number of side branches (P < .001) and was more frequently connected to the precentral sulcus (P < .001) in patients with FCD2 than in control subjects. The PBS was found in 23 (62%) of 37 total patients with FCD2, in six (46%) of 13 with negative MR imaging findings, and in only one control subject. Inter- and intraobserver rates were excellent (0.88 and 0.93, respectively) for the detection of PBS. FCD2 was located either in the depth of the ascending branch of the central sulcus (14 of 23, 61%) or in its immediate vicinity (nine of 23).CONCLUSION:Given its excellent reproducibility and specificity, the PBS, when present, could become a useful qualitative diagnostic MR criterion of FCD2 in the central region.

Objective Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular tropism for the central sulcus. Up to 30% of lesions are undetected (magnetic resonance [MR]-negative FCD patients) or belatedly diagnosed by visual analysis of MR images. We propose an automated sulcus-based method to analyze abnormal sulcal patterns associated with central FCD, taking into account the normal interindividual sulcal variability. Methods We retrospectively studied 29 right-handed patients with FCD in the central region (including 12 MR negative histologically-confirmed cases) and 29 right-handed controls. The analysis of sulcal abnormalities from T1-weighted MR imaging (MRI) was performed using a graph-based representation of the cortical folds and an automated sulci recognition system, providing a new quantitative criterion to describe sulcal patterns, termed sulcus energy. Results Group analysis showed that the central sulcus in the hemisphere ipsilateral to the FCD exhibited an abnormal sulcal pattern compared with controls (p = 0.032). FCDs were associated with abnormal patterns of the central sulci compared with controls (p = 0.006), a result that remained significant when MR-negative and MR-positive patients were considered separately, while the effects of sex, age and MR-field were not significant. At the individual level, sulcus energy alone failed to detect the FCD lesion. We found, however, a significant association between maximum z-scores and the site of FCD (p = 0.0046) which remained significant in MR-negative (p = 0.024) but not in MR-positive patients (p = 0.058). The maximum z-score pointed to an FCD sulcus in four MR-negative and five MR-positive patients. Conclusions We identified abnormal sulcal patterns in patients with FCD of the central region compared with healthy controls. The abnormal sulcal patterns ipsilateral to the FCD and the link between sulcus energy and the FCD location strengthen the interest of sulcal abnormalities in FCD patients.

International audience; Age-related changes in autobiographical memory (AM) recall are characterized by a decline in episodic details, while semantic aspects are spared. This deleterious effect is supposed to be mediated by an inefficient recruitment of executive processes during AM retrieval. To date, contrasting evidence has been reported on the neural underpinning of this decline, and none of the previous studies has directly compared the episodic and semantic aspects of AM in elderly. We asked 20 young and 17 older participants to recall specific and general autobiographical events (i.e., episodic and semantic AM) elicited by personalized cues while recording their brain activity by means of fMRI. At the behavioral level, we confirmed that the richness of episodic AM retrieval is specifically impoverished in aging and that this decline is related to the reduction of executive functions. At the neural level, in both age groups, we showed the recruitment of a large network during episodic AM retrieval encompassing prefrontal, cortical midline and posterior regions, and medial temporal structures, including the hippocampus. This network was very similar, but less extended, during semantic AM retrieval. Nevertheless, a greater activity was evidenced in the dorsal anterior cingulate cortex (dACC) during episodic, compared to semantic AM retrieval in young participants, and a reversed pattern in the elderly. Moreover, activity in dACC during episodic AM retrieval was correlated with inhibition and richness of memories in both groups. Our findings shed light on the direct link between episodic AM retrieval, executive control, and their decline in aging, proposing a possible neuronal signature. They also suggest that increased activity in dACC during semantic AM retrieval in the elderly could be seen as a compensatory mechanism underpinning successful AM performance observed in aging. These results are discussed in the framework of recently proposed models of neural reorganization in aging.

The French Society of Radiology's guide to good use of medical imaging examinations recommends MRI as the first-line examination for exploring cerebrovascular events or disorders. This paper will discuss the main traps in the images when stroke is suspected and provide the technical tips or knowledge necessary for an optimal radiological report.

Objectifs Exposer les principes de l’imagerie de diffusion, ses indications actuelles en pathologie encephalique de l’adulte. Materiels et methodes L’imagerie de diffusion, qui permet une mesure du mouvement microscopique des molecules d’eau, est devenue la sequence-cle de nombreux protocoles d’IRM de l’encephale.Les principes fondamentaux de l’imagerie de diffusion et en tenseur de diffusion seront presentes. Les parametres d’acquisition (gradients de diffusion, facteur b, ponderation en diffusion) seront rappeles. Resultats Les differentes applications cliniques de l’imagerie de diffusion seront illustrees a l’aide d’exemples : lesion ischemique, tumorale, infectieuse, et toxique. L’etude de la substance blanche par tenseur de diffusion ainsi que la tractographie des faisceaux de fibres sera presentee. Conclusion La diffusion est une technique rapide, simple d’utilisation et voit actuellement son champ d’application s’elargir. Le tenseur de diffusion offre la possibilite de detecter et de quantifier des anomalies de la substance blanche non visible en imagerie conventionnelle et de visualiser le trajet des principaux faisceaux de fibres.

Objectifs Presenter les differentes sequences d’exploration des vaisseaux cervicaux en IRM 1,5T et 3T. Messages a retenir L’IRM permet une etude de la lumiere et de la paroi des arteres cervicales. Les sequences ARM avec injection de produit de contraste restent la reference en IRM. Les sequences 3D PC et 3D TOF sont une bonne alternative pour les patients lorsque l’injection est impossible. L’IDEAL permet une saturation homogene de la graisse et une bonne visualisation de l’hematome de paroi en cas de dissection. Les sequences en sang noir donnent un bon contraste entre la lumiere et la paroi. Resume Les sequences recentes d’exploration des arteres cervicales sont presentees : 3D echo-gradient, sequences dynamiques injectees, 3D TOF, 3D contraste de phase (3D PC), IDEAL (Iterative Decomposition water-fat separation with Echo Asymetry and Least-squares estimation), les sequences avec synchronisation cardiaque en sang noir pour l’etude de la lumiere et de la paroi des vaisseaux cervicaux. Nous illustrons l’apport de ces sequences en fonction des differents tableaux cliniques et la facon de les integrer aux protocoles.

Objectifs Rappeler les principes et le mode de realisation des sequences de perfusion cerebrale avec et sans injection de Gadolinium. Materiels et methodes La sequence de perfusion avec injection de Gadolinium est une imagerie du premier passage en echo-planar T2*, duree Resultats La perfusion Gadolinium est facilement realisable. Les echecs sont principalement dus a une mauvaise voie d’abord. Elle est systematiquement utilisee a la phase aigue des AVC dans notre centre. Pour l’exploration des tumeurs, les deux sequences sont interessantes pour preciser la nature de la lesion et son pronostic. L’ASL est interessant chez les patients difficiles a perfuser et en pediatrie. Conclusion Avec ou sans injection de Gadolinium, l’etude de la perfusion peut s’integrer a toute IRM encephalique, meme a 1,5T.

Objectifs Savoir identifier les activites « cibles », susceptibles d’etre ameliorees rapidement. Savoir choisir une demarche d’EPP en fonction de l’objectif choisi. Savoir definir des indicateurs simples d’amelioration de pratiques. Points cles Une EPP n’a de raison d’etre que si elle ameliore une pratique medicale. L’amelioration de la pertinence des demandes constitue un theme d’EPP multidisciplinaire. Une demarche d’EPP simple, voire jugee « simpliste » peut permettre la correction d’un grand nombre d’ecarts par raport au referentiel. Une demarche d’EPP ayant comme theme la planification ou les protocoles d’examen integre les manipulateurs. Resume La deuxieme version de la procedure de certification a pour but l’evaluation du service medical rendu au patient. Elle apprecie le parcours du patient dans l’etablissement et les demarches d’ameliorations mises en œuvre. L’evaluation des pratiques professionnelles (EPP), qui correspond a une action d’amelioration par rapport a une pratique cible, est donc tres liee a cette procedure. Trois approches ont ete definies : la pertinence des pratiques : (reference 40), le risque lie aux soins (reference 41) et la prise en charge medicale des pathologies ou problemes de sante (reference 42). Dans cet expose, les diverses methodes d’EPP utilisables en etablissement de sante seront envisagees a partir d’exemples concrets.

Objectifs Exposer l’apport de l’analyse en temps reel de l’IRM fonctionnelle clinique. Materiels et methodes A partir de notre experience d’utilisation de l’IRMf, nous presenterons l’apport du traitement en temps reel des sequences fonctionnelles. Ce travail repose sur l’analyse d’IRMf « motrice » (reperage du cortex moteur) ou « langage » (etude de la dominance hemispherique pour le langage) dans le cadre du bilan prechirurgical en pathologie tumorale ou epileptique (60 patients, annee 2005). Resultats L’IRMf a ete contributive dans 96 % des cas. Le traitement des images en temps reel permet 1/ de s’assurer de la participation du patient aux epreuves fonctionnelles, en particulier pour les epreuves de langage « silencieuses » ; 2/ de repeter une epreuve en cas d’activation insuffisante ou de mouvements du patient ; 3/ de limiter le nombre d’epreuves a celles necessaires pour conclure. Conclusion L’analyse en temps reel de images d’IRMf permet d’adapter l’examen a chaque patient. Si l’IRMf temps reel ne remplace pas le traitement differe des images, c’est un element cle pour l’obtention d’un examen contributif.

Summary Objectifs Presenter l’etude en IRM haute resolution de la plaque d’atherosclerose de l’artere carotide. Materiels et methodes Des moyens de contention de la tete laissant libre la region cervicale sont indispensables. Deux antennes de surface, en reseau phase, sont positionnees au contact des arteres carotides cervicales. En raison d’un champ d’exploration limite, le positionnement de l’antenne conditionne la qualite des images. Les sequences de reperage verifient que la surface utile des antennes correspond aux bifurcations carotides. Trois sequences sont ensuite realisees : 8 coupes axiales de 3 mm, en haute resolution ( Resultats Cette technique est utilisee pour determiner les differents composants de la plaque d’atherosclerose (cœur lipidique, hemorragie intraplaque, chape fibreuse) afin d’identifier les plaques « a haut risque » emboligene, des plaques a « bas risque ». Des exemples permettront d’illustrer l’interet de cette technique, utilisee dans le cadre d’une etude multicentrique prospective (PHRC 2002). Conclusion L’analyse de la plaque d’atherosclerose en IRM haute resolution devrait permettre d’ameliorer la selection des patients a operer et de suivre l’efficacite de medicaments visant a « stabiliser » les plaques.