Alexandre Krainik

• MD, PhD
• Professor (Full) at Grenoble Alpes University

The majority of intracranial expansive lesions are tumors. However, a wide range of lesions can mimic neoplastic pathology. Differentiating pseudotumoral lesions from brain tumors is crucial to patient management. This article describes the most common intracranial pseudotumors, with a focus on the imaging features that serve as clues to detect pse...

Purpose The purpose of this study was to create an algorithm that combines multiple machine-learning techniques to predict the expanded disability status scale (EDSS) score of patients with multiple sclerosis at two years solely based on age, sex and fluid attenuated inversion recovery (FLAIR) MRI data. Materials and methods Our algorithm combined...

Background Brain MRI parenchymal signal abnormalities have been in association with SARS-CoV-2. Purpose Describe the neuroimaging findings (excluding ischemic infarcts) in patients with severe COVID-19 infection. Methods This was a retrospective study of patients evaluated from March 23th, 2020 to April 27th, 2020 at 16 hospitals. Inclusion crite...

Purpose: New multiple sclerosis (MS) disease-modifying therapies (DMTs), which exert beneficial effects through prevention of relapse, limitation of disability progression, and improvement of patients' quality of life, have recently emerged. Nonetheless, these DMTs are not without associated complications (severe adverse events like. progressive mu...

Objective To assess the clinical usefulness of facet joint cryoneurolysis in patients suffering from back pain of facet origin. Matérial and methods Twenty nine patients suffering from chronic low back pain > 3 months were consecutively included in this single centre between 2015 and 2018 and 45 cryoneurolysis were performed. The decision to perfo...

Introduction. Temporal lobe epilepsy (TLE) accounts for 70-80% of epilepsy in adults (1). The dysfunction (epileptic zone, EZ) is located in the temporal lobe and induces language and memory reorganization of cerebral networks and various degrees of cognitive efficiency. TLE patients should be explored according to a multimodal integrative perspect...

In this dynamic causal modeling (DCM) study, we evaluated the effect of age on the effective connectivity of a cerebral network involved in lexical production. Younger and older adults performed an object naming task during fMRI. The DCM was used to explore the interactions between four regions of interest: the occipital cortex, OC; the lateral tem...

BACKGROUND: Experimental studies led to testing of deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) as a new therapy to treat freezing of gait (FOG) in Parkinson disease (PD). Despite promising initial results fueling a growing interest toward that approach, several clinical studies reported heterogeneity in patient responses. Var...

Purpose: The goal of this retrospective study was to investigate the differential diagnosis of endolymphatic hydrops in patients with Meniere's disease (MD) symptoms by using magnetic resonance imaging (MRI) with intravenous injection of gadolinium chelate and delayed acquisition. Material and method: Two hundred patients (133 women, 67 men; mea...

Background Deep brain stimulation (DBS) has been proposed to treat patients with severe Tourette's syndrome, and open-label trials and two small double-blind trials have tested DBS of the posterior and the anterior internal globus pallidus (aGPi). We aimed to specifically assess the efficacy of aGPi DBS for severe Tourette's syndrome. Methods In t...

Background and purpose: A rapid identification of the etiology of anterior ischemic optic neuropathy is crucial because it determines therapeutic management. Our aim was to assess MR imaging to study the optic nerve head in patients referred with anterior ischemic optic neuropathy, due to either giant cell arteritis or the nonarteritic form of the...

Older adults exhibit normal accuracy in performing word retrieval and generation (lexical production; e.g., object naming) but they are generally slower (longer response times) than younger adults. To maintain this accuracy, older adults recruit compensatory mechanisms and strategies. We focused on two of such possible compensatory mechanisms; one...

Introduction We conducted a retrospective study to identify morphological subgroups of patients referred for AD or aMCI and to seek for differences across neuropsychological performances. Methods One hundred forty-five patients (mean age = 76.01, 88 women and 57 men) referred for AD, either at the stage of dementia or aMCI, were examined using stru...

Hearing loss is a common functional disorder after trauma, and radiologists should be aware of the ossicular, labyrinthine or brain lesions that may be responsible. After a trauma, use of a systematic approach to explore the main functional components of auditory pathways is essential. Conductive hearing loss is caused by the disruption of the cond...

Introduction Les névrites ischémiques optiques antérieures aiguës (NOIAA) sont caractérisées par une mort des cellules ganglionnaires de la rétine et une perte axonale de la partie antérieure du nerf optique (NO). La séquence IRM pondérée par les faisceaux de fibres (TWI) a été développée récemment comme une nouvelle séquence anatomique dérivée de...

Objectifs Les mouvements anormaux hémicorporels, qu’ils soient balliques ou choréo-athétosiques, sont secondaires à une variété de désordres ischémiques, métaboliques ou toxiques. Ils constituent un motif fréquent de consultation aux urgences et de prescription d’examens d’imagerie. L’hyperglycémie sans cétose est une des étiologies décrites. Si le...

Background: Gait and akinesia deterioration in PD patients during the immediate postoperative period of DBS has been directly related to stimulation in the subthalamic region. The underlying mechanisms remain poorly understood. The aim of the present study was to clinically and anatomically describe this side effect. Methods: PD patients present...

The nervous system is frequently involved in patients with infective endocarditis (IE). A systematic review of the literature was realized in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). This study sought to systematically evaluate the published evidence of the contribution of brain magnetic reson...

This fMRI study aimed to explore the effect of normal aging on word retrieval and generation. The question addressed is whether lexical production decline is determined by a direct mechanism, which concerns the language operations or is rather indirectly induced by a decline of executive functions. Indeed, the main hypothesis was that normal aging...

Mild traumatic brain injury (mTBI) is a leading cause of disability in adults, many of whom report a distressing combination of physical, emotional and cognitive symptoms, collectively known as post-concussion syndrome, that persist after the injury. Significant developments in magnetic resonance diffusion imaging, involving voxel-based quantitativ...

Introduction L’accumulation de preuves avant une prise de décision, et la capacité d’attendre avant d’agir, respectivement nommées « impulsivité décisionnelle » et « impulsivité différée », sont des formes du contrôle du comportement, dysfonctionnel dans le trouble obsessionnel compulsif (TOC). Ce travail a exploré les effets de la stimulation céré...

Introduction. This fMRI study explores the effect of normal ageing on the cerebral substrate of word retrieval and generation. Our hypothesis is that normal ageing does not induce loss of lexical knowledge but slowdown of retrieval mechanisms and of access to word representations, by decline of executive functioning. Methods. Participants and inclu...

Objectives: To assess the feasibility of intraparotid facial nerve (VIIn) tractographic reconstructions in estimating the presence of a contact between the VIIn and the tumour, in patients requiring surgical resection of parotid tumours. Methods: Patients underwent MR scans with VIIn tractography calculated with the constrained spherical deconvo...

The assessment of cerebrovascular reactivity (CVR) has shown promising results for its use in medical diagnosis and prognosis, especially in patients suffering from severe intracranial arterial stenosis. However, its quantification remains uncertain because of a large variability inherent in brain anatomy and in methodological settings. To overcome...

Fibromuscular dysplasia (FMD) is an idiopathic, segmentary, non-inflammatory and non-atherosclerotic disease that can affect all layers of both small- and medium-calibre arteries. The prevalence of FMD is estimated between 4 and 6 % in the renal arteries and between 0.3 and 3 % in the cervico-encephalic arteries. FMD most frequently affects the ren...

Improvement of surgical accuracy during DBS-lead implantation has been described recently, leading to "frameless" or "MRI-verified" techniques. However, combining a high-quality definition of the STN using intraoperative 1.5 MRI with the possibility to reduce errors due to co-registration and to monitor lead progression during surgical insertion wh...

Recurrent peripheral vestibulopathy (RPV) is a public health problem, yet the aetiology remains unclear. Recent developments in MRI of endolymphatic hydrops (EH) allow for a better understanding of inner ear disorders. We intended to study the prevalence of EH in patients with RPV, in comparison to those with Meniere's disease (MD). MRI examination...

Cerebral metastases are the commonest central nervous system tumors. The MR assessment should include T1-weighted images with and without enhancement and T2/FLAIR images. They usually appear as multiple lesions with nodular or annular enhancement and are surrounded by edema. They are hypervascularized and have no restriction of their diffusion coef...

Multiparametric quantitative blood oxygenation level dependent (mqBOLD) magnetic resonance Imaging (MRI) approach allows mapping tissular oxygen saturation (StO2) and cerebral metabolic rate of oxygen (CMRO2). To identify hemodynamic alteration related to severe intracranial arterial stenosis (SIAS), functional MRI of cerebrovascular reserve (CVR B...

The subthalamic nucleus (STN) has been shown to be implicated in the control of voluntary action, especially during tasks involving conflicting choice alternatives or rapid response suppression. However, the precise role of the STN during nonmotor functions remains controversial. First, we tested whether functionally distinct neuronal populations s...

The present study assessed the isolated and synergetic effects of hypoxic exposure and prolonged exercise on cerebral volume and subedema and symptoms of acute mountain sickness (AMS). Twelve healthy males performed three semirandomized blinded 11-hour sessions with (1) an inspiratory oxygen fraction (FiO2) of 12% and 4-hour cycling, (2) FiO2=21% a...

Neuropsychiatric fluctuations in Parkinson's disease (PD) are frequent and disabling. One way to investigate them is to assess the ability to inhibit distractive emotional information by a modified emotional Stroop (ES) task. We compared non-depressed, non-demented PD patients with healthy controls. During an acute levodopa challenge, patients perf...

Little is known of the clinical relevance of amygdalar atrophy in Mild Cognitive Impairment (MCI). In this study, hippocampal and amygdalar volumes of 22 MCI patients and 22 controls were derived from magnetic resonance images segmented by an automatic multi-atlas segmentation procedure. The volume loss was greater in the amygdala (41%) than in the...

A 50-year-old man was referred for subacute intracranial hypertension. MRI revealed a well-circumscribed lesion in the posterior fossa that was hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging (figure 1, A and E). Cerebral blood volume map and sequential postcontrast T1-weighted images showed progressive increase in the ho...

Les métastases cérébrales sont les tumeurs les plus fréquentes du système nerveux central. Le bilan IRM doit comporter des séquences pondérées en T1 sans et avec injection, en T2/FLAIR. Elles apparaissent le plus souvent comme des lésions multiples prenant le contraste de façon annulaire ou nodulaire et sont entourées d’œdème. Elles sont hypervascu...

Medulloblastomas are the most common malignant childhood brain tumors arising in the posterior fossa. Treatment improvements for these tumors have meant that there are a greater number of survivors, but this long-term patient survival has increased the awareness of resulting neurocognitive deficits. Impairments in attention, memory, executive funct...

Magnetic resonance imaging (MRI) is the best imaging technique to study the encephalic structures. Knowledge of their topography and orientation in different planes is essential to address neuroimaging studies. The sulcogyral anatomy, deep structures, and the brain vasculature are described. Anatomical applications of functional MRI and the contrib...

Nous présentons ici un protocole expérimental d’imagerie fonctionnelle (IRMf) et sa validation sur onze sujets sains. Ce protocole est destiné à étudier les activations corticales associées au réapprentissage de la parole après exérèse carcinologique au niveau du conduit vocal. Trois tâches parole et non parole sont étudiées : mouvement oro-facial...

Background and purpose: Intravascular angioplasty and stenting of intracranial arterial stenosis provided controversial results. Besides the expertise of the practitioners, the selection of the patients remains challenging. BOLD MRI of the cerebral vasoreactivity (BOLD MRI CVR) to hypercapnia provides reproducible maps of the entire brain of the v...

Current research suggests that amygdalar volumes in patients with Alzheimer's disease (AD) may be a relevant measure for its early diagnosis. However, findings are still inconclusive and controversial, partly because studies did not focus on the earliest stage of the disease. In this study, we measured amygdalar atrophy in 48 AD patients and 82 hea...

Abstract Introduction We conducted a retrospective study to identify morphological subgroups of patients referred for AD or aMCI and to seek for differences across neuropsychological performances. Methods One hundred forty-five patients (mean age=76.01, 88 women and 57 men) referred for AD, either at the stage of dementia or aMCI, were examined usi...

Although neuroimaging studies have revealed specific patterns of reorganization in the sensorimotor control network after stroke, their role in recovery remains unsettled. To review the existing evidence systematically, we performed activation likelihood estimation meta-analysis of functional neuroimaging studies investigating upper limb movement-r...

Radiotherapy and chemotherapy may induce neurological toxicities with different appearances on CT and MRI scans. While optimized radiotherapy techniques have reduced some complications, new unwanted effects have occurred on account of therapeutic protocols involving the simultaneous use of radiotherapy and chemotherapy. Advances in radio-surgery, i...

La tomodensitométrie ou l’IRM de perfusion se sont largement développées ces dernières années et sont accessibles sur la plupart des appareils d’imagerie. La TDM de perfusion a pris une place majeure dans le bilan de l’accident vasculaire cérébral (AVC) ; son rôle doit être précisé pour le diagnostic et la prise en charge thérapeutique du vasospasm...

L’imagerie fonctionnelle de la perfusion permet d’en étudier les propriétés, telles que la vasoréactivité aux gaz circulants, l’autorégulation et le couplage neurovasculaire. En aval d’une sténose artérielle, cette imagerie peut estimer la réserve vasculaire et le risque d’ischémie pour adapter la stratégie thérapeutique. Cette méthode montre les t...

Although the study of cerebral vasoreactivity using fMRI is mainly conducted through the BOLD fMRI modality, owing to its relatively high signal-to-noise ratio (SNR), ASL fMRI provides a more interpretable measure of cerebral vasoreactivity than BOLD fMRI. Still, ASL suffers from a low SNR and is hampered by a large amount of physiological noise. T...

The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hem...

This study aims at describing cortical and subcortical activation patterns associated with functional recovery of speech production after reconstructive mouth surgery. Our ultimate goal is the understanding of how the brain deals with altered relationships between motor commands and auditory/orosensory feedback, and establishes new interarticulator...

Perfusion CT or MRI have been extensively developed over the last years and are accessible on most imaging machines. Perfusion CT has taken a major place in the assessment of a stroke. Its role has to be specified for the diagnosis and treatment of the vasospasm, complicating a subarachnoid hemorrhage. Perfusion MRI should be included in the assess...

Quantification of cerebral blood flow using QUIPSSII pulsed arterial spin labeling requires that the QUIPSS saturation delay TI(1) is shorter than the natural temporal bolus width. Yet the duration of the bolus of tagged spins entering the region of interest varies during vasoactive stimuli such as gaseous challenges or across subjects due to diffe...

Emotional material tends to be better retrieved in memory than neutral material. This emotional enhancement of memory may be related to the attentional effects of the amygdala's response to emotional stimuli. Because early neuropathological changes in Alzheimer's disease involve the amygdala and the hippocampus, it has been suggested that this effe...

The aim of this work was to study cerebral vasoreactivity to hypercapnia in Parkinson's disease (PD) before and after levodopa administration. The prospective study was conducted in 20 patients presenting with PD, using 3T blood oxygenation level-dependent (BOLD) functional MRI (fMRI) covering the whole brain. The hypercapnic stimulus was block-des...

The aim of this study was to compare magnetic resonance imaging (MRI) and histological estimates of the mean vessel diameter (mVD), the vessel density (Density), and the vessel size index (VSI) obtained in the same tumor-bearing animals. Twenty-seven rats bearing intracranial glioma (C6 or RG2) were imaged by MRI. Changes in transverse relaxations...

Background: Prognostication in comatose survivors of cardiac arrest is a major clinical challenge. The authors' objective was to determine whether an assessment with diffusion tensor imaging, a brain magnetic resonance imaging sequence, increases the accuracy of 1 yr functional outcome prediction in cardiac arrest survivors. Methods: Prospective...

Background: Existing methods to predict recovery after severe traumatic brain injury lack accuracy. The aim of this study is to determine the prognostic value of quantitative diffusion tensor imaging (DTI). Methods: In a multicenter study, the authors prospectively enrolled 105 patients who remained comatose at least 7 days after traumatic brain...

Levodopa (L-dopa) effects on the cardinal and axial symptoms of Parkinson's disease (PD) differ greatly, leading to therapeutic challenges for managing the disabilities in this patient's population. In this context, we studied the cerebral networks associated with the production of a unilateral hand movement, speech production, and a task combining...

MR imaging is a tool for multimodality image analysis, making it possible to perform morphologic, metabolic and functional examinations. Abundant and variable information is provided by many different sequences. Knowledge of the different possibilities for MRI enables the clinician to choose the most accurate sequences for the patient's individual...

High-field 3T magnetic resonance imaging (MRI) has entered standard clinical practice over the past decade, and its advantages have already been suggested in areas such as neural, musculoskeletal, pelvic and angiographic imaging. However, high-field systems still pose challenges in terms of their specific absorption rate (SAR) and radiofrequency (R...

Current research suggests that amygdalar volumes in patients with Alzheimer's disease (AD) may be a relevant measure for its early diagnosis. However, findings are still inconclusive and controversial, partly because studies did not focus on the earliest stage of the disease. In this study, we measured amygdalar atrophy in 48 AD patients and 82 hea...

Because of its reversibility and adaptability, deep brain stimulation (DBS) has recently gained interest in psychiatric disorders, such as obsessive-compulsive disorders (OCD) and depression. In OCD, DBS is now an alternative procedure to lesions of fascicles such as the anterior capsule, which links the orbitofrontal cortex, the cingulum, and the...

Objectives: To investigate whether using 3 Tesla (T) instead of 1.5T modifies the data obtained from first-pass perfusion in relation to the quantitative values of cerebral blood volume (CBV) and estimation of micro-vascular leakage (MVL). To describe the differences in data in the setting of neuro-oncology cases and propose explanations based on...

Stereotact Funct Neurosurg. 2012;90:84

The purpose of this study was to evaluate retrospectively whether cerebral blood volume measurement based on pretreatment perfusion MRI is a prognostic biomarker for survival in patients with oligodendroglioma or mixed oligoastrocytoma. Between 1998 and 2004, 54 patients (23 females and 31 males), aged 21-73 years, with oligodendroglioma (or mixed...

Since blood oxygenation level dependent (BOLD) signal changes have been observed using MRI [45] and modulated using neuronal stimuli [4, 46], functional MRI (fMRI) has quickly become the most popular functional neuroimaging technique in clinical practice and cognitive neuroscience. Indeed, high-field MR scanners and BOLD sensitive sequences are now...