CNS tumors with PLAGL1-fusion: beyond ZFTA and YAP1 in the genetic spectrum of supratentorial ependymomas.

A novel methylation class, "neuroepithelial tumor, with PLAGL1 fusion" (NET-PLAGL1), has recently been described, based on epigenetic features, as a supratentorial pediatric brain tumor with recurrent histopathological features suggesting an ependymal differentiation. Because of the recent identification of this neoplastic entity, few histopathological, radiological and clinical data are available. Herein, we present a detailed series of nine cases of PLAGL1-fused supratentorial tumors, reclassified from a series of supratentorial ependymomas, non-ZFTA/non-YAP1 fusion-positive and subependymomas of the young. This study included extensive clinical, radiological, histopathological, ultrastructural, immunohistochemical, genetic and epigenetic (DNA methylation profiling) data for characterization. An important aim of this work was to evaluate the sensitivity and specificity of a novel fluorescent in situ hybridization (FISH) targeting the PLAGL1 gene. Using histopathology, immunohistochemistry and electron microscopy, we confirmed the ependymal differentiation of this new neoplastic entity. Indeed, the cases histopathologically presented as "mixed subependymomas-ependymomas" with well-circumscribed tumors exhibiting a diffuse immunoreactivity for GFAP, without expression of Olig2 or SOX10. Ultrastructurally, they also harbored features reminiscent of ependymal differentiation, such as cilia. Different gene partners were fused with PLAGL1: FOXO1, EWSR1 and for the first time MAML2. The PLAGL1 FISH presented a 100% sensitivity and specificity according to RNA sequencing and DNA methylation profiling results. This cohort of supratentorial PLAGL1-fused tumors highlights: 1/ the ependymal cell origin of this new neoplastic entity; 2/ benefit of looking for a PLAGL1 fusion in supratentorial cases of non-ZFTA/non-YAP1 ependymomas; and 3/ the usefulness of PLAGL1 FISH.

Evaluation of a nnU-Net type automated clinical volumetric tumor segmentation tool for diffuse low-grade glioma follow-up.

BACKGROUND AND PURPOSE: Diffuse low-grade gliomas (DLGG) are characterized by a slow and continuous growth and always evolve towards an aggressive grade. Accurate prediction of the malignant transformation is essential as it requires immediate therapeutic intervention. One of its most precise predictors is the velocity of diameter expansion (VDE). Currently, the VDE is estimated either by linear measurements or by manual delineation of the DLGG on T2 FLAIR acquisitions. However, because of the DLGG's infiltrative nature and its blurred contours, manual measures are challenging and variable, even for experts. Therefore we propose an automated segmentation algorithm using a 2D nnU-Net, to 1) gain time and 2) standardize VDE assessment. MATERIALS AND METHODS: The 2D nnU-Net was trained on 318 acquisitions (T2 FLAIR & 3DT1 longitudinal follow-up of 30 patients, including pre- & post-surgery acquisitions, different scanners, vendors, imaging parameters…). Automated vs. manual segmentation performance was evaluated on 167 acquisitions, and its clinical interest was validated by quantifying the amount of manual correction required after automated segmentation of 98 novel acquisitions. RESULTS: Automated segmentation showed a good performance with a mean Dice Similarity Coefficient (DSC) of 0.82±0.13 with manual segmentation and a substantial concordance between VDE calculations. Major manual corrections (i.e., DSC<0.7) were necessary only in 3/98 cases and 81% of the cases had a DSC>0.9. CONCLUSION: The proposed automated segmentation algorithm can successfully segment DLGG on highly variable MRI data. Although manual corrections are sometimes necessary, it provides a reliable, standardized and time-winning support for VDE extraction to asses DLGG growth.

Immune-mediated diseases involving central and peripheral nervous systems.

BACKGROUND AND PURPOSE: In addition to combined central and peripheral demyelination, other immune diseases could involve both the central nervous system (CNS) and peripheral nervous system (PNS). METHODS: To identify immune-mediated diseases responsible for symptomatic combined central/peripheral nervous system involvement (ICCPs), we conducted a multicentric retrospective study and assessed clinical, electrophysiological, and radiological features of patients fulfilling our ICCP criteria. RESULTS: Thirty patients (20 males) were included and followed during a median of 79.5 months (interquartile range [IQR] = 43-145). The median age at onset was 51.5 years (IQR = 39-58). Patients were assigned to one of four groups: (i) monophasic disease with concomitant CNS/PNS involvement including anti-GQ1b syndrome (acute polyradiculoneuropathy + rhombencephalitis, n = 2), checkpoint inhibitor-related toxicities (acute polyradiculoneuropathy + encephalitis, n = 3), and anti-glial fibrillary acidic protein astrocytopathy (subacute polyradiculoneuropathy and meningoencephalomyelitis with linear gadolinium enhancements, n = 2); (ii) chronic course with concomitant CNS/PNS involvement including paraneoplastic syndromes (ganglionopathy/peripheral hyperexcitability + limbic encephalitis, n = 4); (iii) chronic course with sequential CNS/PNS involvement including POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) syndrome (polyradiculoneuropathy + strokes, n = 2), histiocytosis (polyradiculoneuropathy + lepto-/pachymeningitis, n = 1), and systemic vasculitis (multineuropathy + CNS vasculitis/pachymeningitis, n = 2); and (iv) chronic course with concomitant or sequential CNS/PNS involvement including combined central and peripheral demyelination (polyradiculoneuropathy + CNS demyelinating lesions, n = 10) and connective tissue diseases (ganglionopathy/radiculopathy/multineuropathy + limbic encephalitis/transverse myelitis/stroke, n = 4). CONCLUSIONS: We diagnosed nine ICCPs. The timing of central and peripheral manifestations and the disease course help determine the underlying immune disease. When antibody against neuroglial antigen is identified, CNS and PNS involvement is systematically concomitant, suggesting a common CNS/PNS antigen and a simultaneous disruption of blood-nerve and blood-brain barriers.

Assessment of the hypervascularized fraction of glioblastomas using a volume analysis of dynamic susceptibility contrast-enhanced MRI may help to identify pseudoprogression.

PURPOSE: Although perfusion magnetic resonance imaging (MRI) is widely used to identify pseudoprogression, this advanced technique lacks clinical reliability. Our aim was to develop a parameter assessing the hypervascularized fraction of glioblastomas based on volume analysis of dynamic susceptibility contrast-enhanced MRI and evaluate its performance in the diagnosis of pseudoprogression. METHODS: Patients with primary glioblastoma showing lesion progression on the first follow-up MRI after chemoradiotherapy were enrolled retrospectively. On both initial and first follow-up MRIs, the leakage-corrected cerebral blood volume (CBV) maps were post-processed using the conventional hot-spot method and a volume method, after manual segmentation of the contrast-enhanced delineated lesion. The maximum CBV (rCBVmax) was calculated with both methods. Secondly, the threshold of 2 was applied to the CBV values contained in the entire segmented volume, defining our new parameter: %rCBV>2. The probability of pseudoprogression based on rCBVmax and %rCBV>2 was calculated in logistic regression models and diagnostic performance assessed by receiving operator characteristic curves. RESULTS: Out of 25 patients, 11 (44%) were classified with pseudoprogression and 14 (56%) with true progression based on the Response Assessement in Neuro-Oncology criteria. rCBVmax was lower for pseudoprogression (3.4 vs. 7.6; p = 0.033) on early follow-up MRI. %rCBV>2, was lower for pseudoprogression on both initial (57.5% vs. 71.3%; p = 0.033) and early follow-up MRIs (22.1% vs. 51.8%; p = 0.0006). On early follow-up MRI, %rCBV>2 had the largest area under the curve for the diagnosis of pseudoprogression: 0.909 [0.725-0.986]. CONCLUSION: The fraction of hypervascularization of glioblastomas as assessed by %rCBV>2 was lower in tumours that subsequently developed pseudoprogression both on the initial and early follow-up MRIs. This fractional parameter may help identify pseudoprogression with greater accuracy than rCBVmax.

Pathologic and MRI analysis in acute atypical inflammatory demyelinating lesions.

BACKGROUND: The diagnosis of atypical inflammatory demyelinating lesions can be difficult. Brain biopsy is often required to exclude neoplasms. Moreover, the relationship between these lesions and multiple sclerosis and NMOSD is not clear. OBJECTIVES: Our objectives were to describe radiological and pathological characteristics of patients with acute inflammatory demyelinating lesions. METHODS: We retrospectively identified patients with brain biopsy performed for diagnostic uncertainty revealing a demyelinating lesion. A complete clinical, biological, radiological and pathological analysis was performed. RESULTS: Twenty patients (15 with a single lesion) were included. MRI disclosed a wide range of lesions including infiltrative lesions (40%), ring-like lesion (15%) Baló-like lesion (15%) and acute haemorrhagic leukoencephalitis (20%). In spite of a marked heterogeneity, some findings were common: a peripheral B1000 hyperintense rim (70%), a slight oedema with mild mass effect (75%) and an open-rim peripheral enhancement (75%). Histopathology revealed that all cases featured macrophages distributed throughout, extensive demyelination, axonal preservation and absence of haemorrhagic changes. In the majority of cases, macrophages were the predominant inflammatory infiltrate and astrocytes were reactive and dystrophic. Aquaporin-4 staining was systematically preserved. After a mean follow-up of 5 years (1-12), 16/20 patients had a diagnosis of monophasic acute atypical inflammatory demyelinating lesion. One patient was diagnosed with MS and 3 with AQP4 negative NMOSD. DISCUSSION: Although imaging findings in patients with atypical inflammatory demyelinating lesions are heterogeneous, some common features such as peripheral DWI hyperintense rim with open-rim enhancement and absence of oedema argue in favour of a demyelinating lesion and should preclude a brain biopsy. In this context, AQP4 staining is systematically preserved and argues against an AQP4-positive NMOSD. Moreover, long-term follow-up is characterized by low recurrence rate.

Data-Driven Predictive Models of Diffuse Low-Grade Gliomas Under Chemotherapy.

Diffuse low-grade gliomas (DLGG) are brain tumors of young adults. They affect the quality of life of the inflicted patients and, if untreated, they evolve into higher grade tumors where the patient's life is at risk. Therapeutic management of DLGGs includes chemotherapy, and tumor diameter is particularly important for the follow-up of DLGG evolution. In fact, the main clinical basis for deciding whether to continue chemotherapy is tumor diameter growth rate. In order to reliably assist the doctors in selecting the most appropriate time to stop treatment, we propose a novel clinical decision support system. Based on two mathematical models, one linear and one exponential, we are able to predict the evolution of tumor diameter under Temozolomide chemotherapy as a first treatment and thus offer a prognosis on when to end it. We present the results of an implementation of these models on a database of 42 patients from Nancy and Montpellier University Hospitals. In this database, 38 patients followed the linear model and four patients followed the exponential model. From a training data set of a minimal size of five, we are able to predict the next tumor diameter with high accuracy. Thanks to the corresponding prediction interval, it is possible to check if the new observation corresponds to the predicted diameter. If the observed diameter is within the prediction interval, the clinician is notified that the trend is within a normal range. Otherwise, the practitioner is alerted of a significant change in tumor diameter.

Transient immediate postoperative homotopic functional disconnectivity in low-grade glioma patients.

Background and purpose: The aim of this longitudinal study is to evaluate large-scale perioperative resting state networks reorganization in patients with diffuse low-grade gliomas following awake surgery. Materials and methods: Eighty-two patients with diffuse low-grade gliomas were prospectively enrolled and underwent awake surgical resection. Resting-state functional images were acquired at three time points: preoperative (MRI-1), immediate postoperative (MRI-2) and three months after surgery (MRI-3). We simultaneously performed perfusion-weighted imaging. Results: Comparing functional connectivity between MRI-1 and MRI-2, we observed a statistically significant functional homotopy decrease in cortical and subcortical supratentorial structures (P < 0.05). A functional homotopy increase was observed between MRI-2 and MRI-3 in parietal lobes, cingulum and putamen (P < 0.05). No significant functional connectivity modification was noticed between MRI-1 and MRI-3. Regional cerebral blood flow appeared transiently reduced on MRI-2 (P < 0.05). No correlation between neurological deficit and interhemispheric connectivity results was found. Conclusion/interpretation: We found a supratentorial widely distributed functional homotopy disruption between preoperative and immediate postoperative time points with a complete restitution three months after surgery with simultaneous variation of regional cerebral blood flow.

Osteomyelitis of the jaw: time to rethink the bone sampling strategy?

This work aims at describing the diversity of osteomyelitis of the jaw (OJ) and at assessing the relevance of a new method designed to avoid salivary contamination during bone sampling in order to improve microbiological analysis and clinical decision-making. We reviewed medical and microbiological data of patients with a suspected OJ based on clinical and/or CT-scan signs and at least one bone sample made for microbiological analysis. During the study period, a new procedure for intraoral bone sampling was elaborated by surgeons and infectious diseases specialists authoring this article (based on stratified samples, cleaning of the surgical site and change of instruments between each sample). A comparison of the microbiological analyses between the two procedures was performed. From 2012 to 2017, 56 patients were included. Median age was 58 years (11-90), sex ratio: 1.24. Main risk factors were having a dental disease (n = 24) or cancer (n = 21). Nineteen patients with the new sample procedure were compared to 37 patients with standard procedure, especially non-cancer patients (n = 16 and 19, respectively). With the new procedure, a median of 3 (1-7) microorganisms per sample was recovered, vs. 7 (1-14) with the former (p < 0.001), a significant decrease of the microbial density was observed for all types of microbes, especially in deeper samples and cultures were more frequently sterile. The way sampling is managed deeply influences microbiological analysis. This strategy facilitates the distinction between pathogens and contaminants and should constitute the first step toward an evidence-based antimicrobial strategy for OJ.

Recovery of functional connectivity of the sensorimotor network after surgery for diffuse low-grade gliomas involving the supplementary motor area.

OBJECTIVE The supplementary motor area (SMA) syndrome is a well-studied lesional model of brain plasticity involving the sensorimotor network. Patients with diffuse low-grade gliomas in the SMA may exhibit this syndrome after resective surgery. They experience a temporary loss of motor function, which completely resolves within 3 months. The authors used functional MRI (fMRI) resting state analysis of the sensorimotor network to investigate large-scale brain plasticity between the immediate postoperative period and 3 months' follow-up. METHODS Resting state fMRI was performed preoperatively, during the immediate postoperative period, and 3 months postoperatively in 6 patients with diffuse low-grade gliomas who underwent partial surgical excision of the SMA. Correlation analysis within the sensorimotor network was carried out on those 3 time points to study modifications of its functional connectivity. RESULTS The results showed a large-scale reorganization of the sensorimotor network. Interhemispheric connectivity was decreased in the postoperative period, and increased again during the recovery process. Connectivity between the lesion side motor area and the contralateral SMA rose to higher values than in the preoperative period. Intrahemispheric connectivity was decreased during the immediate postoperative period and had returned to preoperative values at 3 months after surgery. CONCLUSIONS These results confirm the findings reported in the existing literature on the plasticity of the SMA, showing large-scale modifications of the sensorimotor network, at both inter- and intrahemispheric levels. They suggest that interhemispheric connectivity might be a correlate of SMA syndrome recovery.

Role of the left frontal aslant tract in stuttering: a brain stimulation and tractographic study.

The neural correlates of stuttering are to date incompletely understood. Although the possible involvement of the basal ganglia, the cerebellum and certain parts of the cerebral cortex in this speech disorder has previously been reported, there are still not many studies investigating the role of white matter fibers in stuttering. Axonal stimulation during awake surgery provides a unique opportunity to study the functional role of structural connectivity. Here, our goal was to investigate the white matter tracts implicated in stuttering, by combining direct electrostimulation mapping and postoperative tractography imaging, with a special focus on the left frontal aslant tract. Eight patients with no preoperative stuttering underwent awake surgery for a left frontal low-grade glioma. Intraoperative cortical and axonal electrical mapping was used to interfere in speech processing and subsequently provoke stuttering. We further assessed the relationship between the subcortical sites leading to stuttering and the spatial course of the frontal aslant tract. All patients experienced intraoperative stuttering during axonal electrostimulation. On postsurgical tractographies, the subcortical distribution of stimulated sites matched the topographical position of the left frontal aslant tract. This white matter pathway was preserved during surgery, and no patients had postoperative stuttering. For the first time to our knowledge, by using direct axonal stimulation combined with postoperative tractography, we provide original data supporting a pivotal role of the left frontal aslant tract in stuttering. We propose that this speech disorder could be the result of a disconnection within a large-scale cortico-subcortical circuit subserving speech motor control.

The left inferior fronto-occipital fasciculus subserves language semantics: a multilevel lesion study.

Consequential works in cognitive neuroscience have led to the formulation of an interactive dual-stream model of language processing: the dorsal stream may process the phonological aspects of language, whereas the ventral stream may process the semantic aspects of language. While it is well-accepted that the dorsal route is subserved by the arcuate fasciculus, the structural connectivity of the semantic ventral stream is a matter of dispute. Here we designed a longitudinal study to gain new insights into this central but controversial question. Thirty-one patients harboring a left diffuse low-grade glioma­a rare neurological condition that infiltrates preferentially white matter associative pathways­were assessed with a prototypical task of language (i.e. verbal fluency) before and after surgery. All were operated under local anesthesia with a cortical and subcortical brain mapping­enabling to identify and preserve eloquent structures for language. We performed voxel-based lesion-symptom (VLSM) analyses on pre- and postoperative behavioral data. Preoperatively, we found a significant relationship between semantic fluency scores and the white matter fibers shaping the ventro-lateral connectivity (P < 0.05 corrected). The statistical map was found to substantially overlap with the spatial position of the inferior fronto-occipital fasciculus (IFOF) (37.7%). Furthermore, a negative correlation was observed between semantic fluency scores and the infiltration volumes in this fasciculus (r = -0.4, P = 0.029). Postoperatively, VLSM analyses were inconclusive. Taken as a whole and when combined with the literature data, our findings strengthen the view that the IFOF plays an essential role in semantic processing and may subserve the direct ventral pathway of language.

Role of fronto-striatal tract and frontal aslant tract in movement and speech: an axonal mapping study.

Despite a better understanding of their anatomy, the functional role of frontal pathways, i.e., the fronto-striatal tract (FST) and frontal aslant tract (FAT), remains obscure. We studied 19 patients who underwent awake surgery for a frontal glioma (14 left, 5 right) by performing intraoperative electrical mapping of both fascicles during motor and language tasks. Furthermore, we evaluated the relationship between these tracts and the eventual onset of transient postoperative disorders. We also performed post-surgical tract-specific measurements on probabilistic tractography. All patients but one experienced intraoperative inhibition of movement and/or speech during subcortical electrostimulation. On postoperative tractography, the subcortical distribution of stimulated sites corresponded to the spatial course of the FST and/or FAT. Furthermore, we found a significant correlation between postoperative worsening and distances between these tracts and resection cavity. A resection close to the (right or left) FST was correlated with transitory motor initiation disorders (p = 0.026), while a resection close to the left FAT was associated with transient speech initiation disorders (p = 0.003). Moreover, the measurements of average distances between resection cavity and left FAT showed a positive correlation with verbal fluency in both semantic (p = 0.019) and phonemic scores (p = 0.017), while average distances between surgical cavity and left FST showed a positive correlation with verbal fluency scores in both semantic (p = 0.0003) and phonemic modalities (p = 0.037). We suggest that FST and FAT would cooperatively play a role in self-initiated movement and speech, as a part of "negative motor network" involving the pre-supplementary motor area, left inferior frontal gyrus and caudate nucleus.

Disrupting posterior cingulate connectivity disconnects consciousness from the external environment.

Neurophysiological and neuroimaging studies including both patients with disorders of consciousness and healthy subjects with modified states of consciousness suggest a crucial role of the medial posteroparietal cortex in conscious information processing. However no direct neuropsychological evidence supports this hypothesis and studies including patients with restricted lesions of this brain region are almost non-existent. Using direct intraoperative electrostimulations, we showed in a rare patient that disrupting the subcortical connectivity of the left posterior cingulate cortex (PCC) reliably induced a breakdown in conscious experience. This acute phenomenon was mainly characterized by a transient behavioral unresponsiveness with loss of external connectedness. In all cases, when he regained consciousness, the patient described himself as in dream, outside the operating room. This finding suggests that functional integrity of the PPC connectivity is necessary for maintaining consciousness of external environment.

Surgical management of diffuse low-grade gliomas associated with other intracranial diseases.

BACKGROUND: The association of diffuse, low-grade glioma (DLGG) with other intracranial pathologies is a rare condition, raising the question of what constitutes its most effective therapeutic management. It is not known whether this is a simple coincidence or whether there is a higher significant risk involved with the co-existence of DLGG and another disease. We report the first consecutive series of nine patients who underwent surgical resection for such a glioma. METHOD: We reviewed DLGGs removed between 1998 and 2013 that were associated with another intracranial pathology. For all cases, we collected and analyzed information regarding clinico-radiological features, surgical procedures, and clinical outcomes. RESULTS: Nine consecutive patients (four men, five women, mean age: 38.8 years) presented with a conjunction of DLGG and another disease: two cases of vestibular schwannoma, two pituitary adenomas, two meningiomas, one lymphoma, one arteriovenous malformation, and one case of multiple sclerosis. The DLGG was diagnosed because of seizures in four patients and incidentally in the other five patients. The average delay between the diagnosis of the glioma and its resection was 40.8 months (range 1-84 months). The mean follow-up after surgery was 43 months (6-120 months). Gross-total or subtotal resection was achieved in all cases. There were no cases of mortality or permanent morbidity associated with surgery. The Karnofsky Performance Scale score was 90 or 100 in all cases. The associated pathology was treated surgically in three cases, medically in four cases, and tracked under observation in two cases. These intracranial diseases, especially meningiomas and pituitary adenomas, might have a significant higher risk to be associated with DLGGs in comparison with their incidence and prevalence in the general population. CONCLUSIONS: Active management of this rare, dual pathology allows patients to enjoy a normal and prolonged quality of life. We therefore suggest considering early and maximal surgical resection as the first therapeutic option for DLGGs combined with another intracranial disease, as is done in the case of isolated DLGGs.

Surgery for gliomas involving the left inferior parietal lobule: new insights into the functional anatomy provided by stimulation mapping in awake patients.

OBJECT: Surgery in the left dominant inferior parietal lobule (IPL) is challenging because of a high density of somatosensory and language structures, both in the cortex and white matter. In the present study, on the basis of the results provided by direct cerebral stimulation in awake patients, the authors revisit the anatomofunctional aspects of surgery within the left IPL. METHODS: Fourteen consecutive patients underwent awake craniotomy for a glioma involving the left IPL. Intraoperative motor, sensory, and language mapping was performed before and during the tumor removal, at both the cortical and subcortical levels, to optimize the extent of resection, which was determined based on functional boundaries. Anatomofunctional correlations were performed by combining the results of intraoperative mapping and those provided by pre- and postoperative MR imaging. RESULTS: At the cortical level, the primary somatosensory area (retrocentral gyrus) limited the resection anteriorly in all cases, at least partially. Less frequently, speech arrest or articulatory problems were observed within the parietal operculum (4 cases). The lateral limit was determined by language sites that were variably distributed. Anomia was the most frequent response (9 cases) at the posterior third of the superior (and/or middle) temporal gyrus. Posteriorly, less reproducible reorganized language sites were seldom observed in the posterior portion of the angular gyrus (2 cases). At the subcortical level, in addition to somatosensory responses due to stimulation of the thalamocortical pathways, articulatory disturbances were induced by stimulation of white matter in the anterior and lateral part of the surgical cavity (11 cases). This tract anatomically corresponds to the horizontal portion of the lateral segment of the superior longitudinal fascicle (SLF III). Deeper and superiorly, phonemic paraphasia was the main language disturbance (12 cases), elicited by stimulation of the posterosuperior portion of the arcuate fascicle. All these eloquent structures were surgically preserved. Despite slight cognitive disorders (working memory, writing, or calculation) in 6 cases, no patient retained a severe or a moderate postoperative deficit (except one with right hemianopia [mean follow-up 41.8 months]). Resection was total or near total in 9 patients and partial in 3 cases. CONCLUSIONS: To the authors' knowledge, this is the first series dedicated to the surgery of gliomas involving the left IPL. Interestingly, a certain degree of interindividual variability was observed in the distribution of the cortical maps, especially for language. Therefore, it is suggested that no rigid pattern of resection can be considered within the left IPL, and that surgery in this region should be performed in awake patients to adapt the tumor removal to individual functional limits. Nonetheless, several landmarks have been regularly identified, especially at the subcortical levels (SLF III and arcuate fascicle); a better knowledge of these functional tracts could be helpful to optimize functional outcomes.

Diffusion tractography: methods, validation and applications in patients with neurosurgical lesions.

Diffusion tensor imaging (DTI) tractography is increasingly used in presurgical mapping in tumors located in eloquent areas since it is the only non invasive technique that permits in vivo dissection of white matter tracts. Concordance between the DTI tracts and subcortical electrical intraoperative mapping is high, and DTI tractography has proven useful to guide surgery. However, it presents limitations due to the technique and the tumor, which must be known before using the images in the operative room. This review focuses on the possibilities and limits of DTI imaging in intraoperative tumoral mapping and presents an overview of current knowledge.

Magnetic resonance imaging evaluation of cerebral cavernous malformations with susceptibility-weighted imaging.

BACKGROUND: Cerebral cavernous malformations (CCMs) can be sporadic or inherited, the latter characterized by multiple lesions. Novel imaging sequences have increased the sensitivity of detecting multiple CCMs. OBJECTIVE: To compare T2-weighted gradient echo (T2*GRE) and susceptibility-weighted imaging (SWI) sequences in familial and sporadic CCM to assess their respective sensitivity. METHODS: This prospective study included 23 consecutive cases grouped as multifocal/familial CCMs (n=14), solitary/clustered sporadic CCMs with developmental venous anomaly (n=8), and postirradiation CCMs (n=1). Brain magnetic resonance imaging included T2*GRE and SWI sequences. Two radiologists independently counted the number of lesions on each sequence. The difference in the number of lesions on both sequences was compared, and interobserver agreement was evaluated. RESULTS: In multifocal/familial cases, a mean of 34.7 lesions were detected on T2*GRE and 66.9 on SWI (P=.001). The difference of lesion prevalence with the 2 techniques was significant (P=.006), with strong interobserver correlation for the T2*GRE sequence (P<.001) and SWI sequence (P<.001). Patients with solitary/clustered sporadic CCMs, including those associated with venous anomaly, had no difference in lesion prevalence in the 2 sequences. CONCLUSION: SWI is more sensitive than T2*GRE in detecting CCM in multifocal/familial CCMs. Among cases classified as solitary/clustered with conventional imaging, including those associated with venous anomaly, the SWI did not impart additional sensitivity or reveal occult lesions not evident on T2*GRE sequence. No case was changed from the solitary/clustered to the multifocal clinical category because of SWI.