Intelligence Artificielle en Imagerie Neurovasculaire

L'intelligence artificielle joue un rôle croissant dans l'imagerie diagnostique et thérapeutique des maladies neurovasculaires. Nous reverrons ici la portée et l'histoire de l'IA et ses applications récentes et potentielles en imagerie neurovasculaire, en traitant des pathologies les plus courantes. Nous verrons comment les modèles d'IA contribuent au diagnostic en imagerie neurovasculaire, et comment ils présentent un potentiel intéressant pour l’imagerie quantitative. Nous verrons également comment ils élargissent le potentiel des images en fournissant des informations invisibles à l'œil humain. Nous verrons que le rôle de l'IA ne se limite pas au diagnostic, mais s'applique à toutes les étapes du workflow en imagerie, y compris les aspects "non interprétatifs". Enfin, nous discuterons des implications, limites et biais de l'IA en imagerie neurovasculaire, en rappelant que son champ d'application en médecine est actuellement étroit et essentiellement utile pour répondre à des applications spécifiques.</p

Influence of Gamma-hydroxybutyric acid (GHB) in human reward processing: a pharmacological fMRI study

Gamma-hydroxybutyric acid (GHB) is a recreational drug, as well as a treatment for narcolepsy and against substance dependence. Recent animal research suggests that at recreational doses GHB may increase mesocorticolimbic dopamine (DA) signaling by reducing inhibitory influence from GABAergic interneurons on DA neurons in the substantia nigra/ ventral tegmental area (SN/VTA). Here, we used functional MRI to test how enhanced SN/ VTA DA transmission after GHB administration affects the neural processing of rewards in healthy humans while they played a gambling-like task. In trials associated with rewards, GHB increased ventral striatum activity with parallel increases in behavioral impulsivity. Moreover, fMRI signal in the SN/VTA positively correlated with individual doses of GHB. By contrast, during feedback processing, GHB mostly reduced response in the orbitofrontal cortex and across a salience network which is involved in identifying relevant internal and extrapersonal stimuli in order to guide behavior (including the amygdala, anterior cingulate cortex, insula, habenula), and with distinct effects for actual gains and losses. These data are consistent with increased phasic response of DA neurons in the SN/VTA, affecting reward processing at remote target regions of the mesocorticolimbic DA circuit. Moreover, reduced reactivity to feedbacks (rewards and losses) across a salience network might also explain why GHB has only a weak reinforcing capacity. These findings do not only provide unprecedented insights into the mechanisms of action of GHB in humans at the macroscopic systems level, but may also have important implications for understanding the multifaceted actions of GHB as both a recreational and therapeutic drug

Confidence of emotion expression recognition recruits brain regions outside the face perception network

Metacognitive beliefs about emotions expressed by others are crucial to social life, yet very little studied. To what extent does our confidence in emotion expression recognition depend on perceptual or other non-perceptual information? We obtained behavioral and magnetic resonance imaging measures while participants judged either the emotion in ambiguous faces or the size of two lines flanking these faces, and then rated their confidence on decision accuracy. Distinct behavioral and neural mechanisms were identified for confidence and perceptual decision in both tasks. Participants overestimated their emotion recognition (ER) accuracy, unlike visual size judgments. Whereas expression discrimination recruited several areas in the face-processing network, confidence for ER uniquely engaged the bilateral retrosplenial/posterior cingulate complex and left parahippocampal gyrus. Further, structural white matter connectivity of the former region predicted metacognitive sensitivity. These results highlight a key role for brain mechanisms integrating perception with contextual mnemonic information in the service of confidence during E

Double stent-retriever technique for mechanical thrombectomy : a systematic review and meta-analysis

Background: Mechanical thrombectomy using a double stent-retriever technique has recently been described for the treatment of acute ischemic stroke, but its efficacy and safety are not well established. Purpose: The aim of this systematic review and meta-analysis was to evaluate reports of the use of double stent-retriever during the endovascular treatment of patients with ischemic stroke. Data sources: The PubMed, Embase, Web of Science and Scopus databases were searched to identify all studies (clinical trials, cohorts series and case reports) investigating the utility of double stent-retriever for the treatment of stroke. The study is reported in accordance with PRISMA 2020 guidelines and was prospectively registered in PROSPERO (BLINDED FOR PEER REVIEW). Study selection: 17 studies involving a total of 128 patients with large vessel occlusions predominantly in the anterior circulation (93.0%) were identified. Data analysis: Outcomes of interest were the prevalence of successful recanalization (mTICI ≥2b) and a first-pass effect following double stent-retriever, as well as complications such as iatrogenic dissections and subarachnoid hemorrhage. Data were pooled using a random-effects model. Data synthesis: Double stent-retriever was used as a rescue strategy in occlusions refractory to conventional endovascular treatment in 68.7% (88/128) of patients and as a first-line strategy in 31.3% (40/128) patients. Double stent-retriever achieved an overall final mTICI ≥2b in 92.6% cases with a first-pass effect of 76.6%. The complication rate remained low, with 0.37% dissection and 1.56% subarachnoid hemorrhage. Limitations: Limitations of the study include (1) a large number of case reports or small series, (2) a meta-analysis of proportions with no statistical comparison to a control group, and (3) the lack of access to patient-level data. Conclusions: Our findings suggest that double stent-retriever thrombectomy may be safe and associated with good recanalization outcomes, but prospective comparative studies are needed to determine which patients may benefit from this endovascular procedure. Abbreviations: AICH = asymptomatic intracranial hemorrhage; AIS = acute ischemic stroke; DSR = double stent-retriever; FPE = first pass effect; ICH = intracranial hemorrhage; LVO = large vessel occlusion; MT = mechanical thrombectomy; SAH = subarachnoid hemorrhage; SICH = symptomatic intracranial hemorrhage; SSR = single stent-retriever.</p

Is Contrast Medium Really Needed for Follow-up MRI of Untreated Intracranial Meningiomas?

Recent concerns relating to tissue deposition of gadolinium are favoring the use of noncontrast MR imaging whenever possible. The purpose of this study was to assess the necessity of gadolinium contrast for follow-up MR imaging of untreated intracranial meningiomas

Caffeine impact on working memory-related network activation patterns in early stages of cognitive decline

Recent evidence indicates that caffeine may have a beneficial effect on cognitive decline and dementia. The current investigation assessed the effect of acute caffeine administration on working memory during the earliest stage of cognitive decline in elderly participants

Shoulder apprehension impacts large-scale functional brain networks

Shoulder apprehension is defined as anxiety and resistance in patients with a history of anterior glenohumeral instability. It remains unclear whether shoulder apprehension is the result of true recurrent instability or a memorized subjective sensation. We tested whether visual presentation of apprehension videos modifies functional brain networks associated with motor resistance and anxiety

Benchtop evaluation of a double stent retriever thrombectomy technique for acute ischemic stroke treatment

Background and purpose: A mechanical thrombectomy technique using a double stent retriever approach has been reported for the treatment of patients with acute ischemic stroke. The purpose of this study was to perform a benchtop evaluation of the mechanism of action and efficacy of a double-stent retriever approach compared to a single-stent retriever approach. Materials and methods: In vitro, mechanical thrombectomy procedures were performed in a vascular phantom reproducing an M1-M2 occlusion with two different clot analog consistencies (soft and hard). We compared the double stent retriever approach to the single stent retriever approach and recorded the recanalization rate, distal embolization, and retrieval forces of each mechanical thrombectomy procedure. Results: The double stent retriever approach achieved a higher recanalization rate and lower embolic complications compared to the single stent retriever approach. This seems to stem from two facts: the greater probability of targeting the correct artery with two stents in the case of bifurcation occlusion, and an improved clot capture mechanism using the double stent retriever approach. However, the double stent retriever was associated with an increased initial retrieval force. Conclusions: In vitro evaluation of the mechanism of action of the double stent retriever provided explanations that appear to support the high efficacy of such an approach in patient cohorts and could help operators when selecting the optimal mechanical thrombectomy strategy in cases of arterial occlusions difficult to treat with a single stent retriever.</p

Resting-State Brain Activity for Early Prediction Outcome in Postanoxic Patients in a Coma with Indeterminate Clinical Prognosis

Early outcome prediction of postanoxic patients in a coma after cardiac arrest proves challenging. Current prognostication relies on multimodal testing, using clinical examination, electrophysiologic testing, biomarkers, and structural MR imaging. While this multimodal prognostication is accurate for predicting poor outcome (ie, death), it is not sensitive enough to identify good outcome (ie, consciousness recovery), thus leaving many patients with indeterminate prognosis. We specifically assessed whether resting-state fMRI provides prognostic information, notably in postanoxic patients in a coma with indeterminate prognosis early after cardiac arrest, specifically for good outcome