Preoperative Diffusion Tensor Imaging Research Articles

Endoscopic transorbital approach for resection of mediobasal temporal lesions using an optic radiation-sparing strategy.

The endoscopic transorbital approach (ETOA) has emerged as a promising minimally invasive technique for resection of lesions in the mediobasal temporal region (MTR) due to its potential to preserve the integrity of the optic radiation (OR). This study evaluated the safety and efficacy of ETOA using an OR-sparing surgical strategy for mediobasal temporal lesions. A retrospective review was conducted of the medical records of 15 patients (7 females and 8 males) who underwent ETOA for lesions in the MTR between November 2017 and November 2022. Preoperative diffusion tensor imaging (DTI) tractography of the OR was utilized in all cases for surgical planning to visualize the spatial relations between the OR and the target mediobasal temporal lesion. The median age of the treated patients was 43 years (range 22-76 years), with a median follow-up duration of 12 months (range 6-35 months). Eleven lesions (73.3%) involved only the anterior segment of the MTR, while 4 lesions (26.7%) affected both the anterior and middle segments. Gross-total resection was achieved in 13 patients (86.7%) and subtotal resection in 2 (13.3%). The final pathologies included low-grade glioma (n = 5), cavernous malformation (n = 3), glioblastoma multiforme (n = 2), multinodular and vacuolating neuronal tumor (n = 1), pleomorphic xanthoastrocytoma (n = 1), anaplastic oligodendroglioma (n = 1), adenoid cystic carcinoma (n = 1), and metastatic renal cell carcinoma (n = 1). Postoperative neuro-ophthalmological examinations revealed that all patients maintained their previous visual function. Follow-up DTI tractography further confirmed the preservation of the preoperative ORs in the treated patients. No postoperative CSF leaks, infections, or cosmetic problems occurred in this series. The combined use of ETOA and OR tractography appears to be a feasible approach for resecting lesions involving the MTR, especially in the anterior segment. In the authors' experience, this surgical strategy enables maximal safe resection while minimizing the risk of postoperative visual dysfunction. Further studies with larger sample sizes are warranted to validate these findings and assess long-term outcomes.

A retrospective case-control study on the effectiveness of preoperative diffusion tensor imaging for mitigating nerve injury in extreme lateral interbody fusion surgery

Extreme Lateral Interbody Fusion (XLIF) has been established as an effective treatment for degenerative disorders of the lumbar spine. Nevertheless, there is a potential risk of lumbar plexus damage associated with XLIF, especially during surgeries at the L4-5 segment. Diffusion Tensor Imaging (DTI) evaluates the directional diffusion of water molecules in tissue, providing a more intricate depiction of internal tissue microstructure compared to conventional MRI techniques. The capability of DTI sequences to elucidate the 3-dimensional interplay between lumbar nerve pathways and adjacent musculoskeletal structures, potentially reducing the incidence of nerve injury complications related to XLIF, remains to be established. This study evaluates the effectiveness of preoperative Diffusion Tensor Imaging (DTI) in reducing neurological complications after Extreme Lateral Interbody Fusion (XLIF) surgeries at the L4-5 level, focusing on the interaction between lumbar nerves and the psoas major muscle. Retrospective case-control study. The study included 128 patients undergoing XLIF surgery for degenerative disorders at the L4-5 segment: 68 in the traditional group and 62 in the DTI group. The study assessed Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) scores, along with complication rates. It also documented psoas major muscle morphology and its correlation with nerve pathways. A retrospective analysis of 128 patients undergoing XLIF surgery for degenerative disorders at the L4-5 segment between February 2020 and August 2022 was conducted. The cohort was divided into a traditional group (68 patients) receiving presurgery MRI scans to identify surgical entry points at the intervertebral space midpoint (Zones II-III junction) and a DTI group (62 patients) who additionally underwent preoperative DTI to customize entry points. The study evaluated VAS and ODI scores, complication rates, psoas major muscle morphology, and its interaction with nerve pathways. The traditional group uniformly chose the Zone II-III junction for entry. In contrast, the DTI group's entry points varied. Postoperative follow-up revealed significant improvements in VAS and ODI scores in both groups. However, the DTI group experienced fewer immediate postoperative complications such as thigh pain, numbness, and motor disturbances. The study also noted a ventral shift in nerve positioning in patients with elevated psoas muscles. Preoperative DTI effectively maps the relationship between the psoas major muscle and lumbar nerves. Tailoring surgical entry points based on DTI results significantly reduces the risk of nerve damage in XLIF surgeries. The study underscores the importance of recognizing variability in lumbar nerve pathways due to differing psoas muscle morphologies, highlighting a higher risk of nerve injury in patients with elevated psoas muscles during XLIF procedures.

Utility of diffusion tensor imaging and generalized q-sampling imaging for predicting short-term clinical effect of deep brain stimulation in Parkinson’s disease

PurposeTo assess whether diffusion tensor imaging (DTI) and generalized q-sampling imaging (GQI) metrics could preoperatively predict the clinical outcome of deep brain stimulation (DBS) in patients with Parkinson’s disease (PD).MethodsIn this single-center retrospective study, from September 2021 to March 2023, preoperative DTI and GQI examinations of 44 patients who underwent DBS surgery, were analyzed. To evaluate motor functions, the Unified Parkinson’s Disease Rating Scale (UPDRS) during on- and off-medication and Parkinson’s Disease Questionnaire-39 (PDQ-39) scales were used before and three months after DBS surgery. The study population was divided into two groups according to the improvement rate of scales: ≥ 50% and < 50%. Five target regions, reported to be affected in PD, were investigated. The parameters having statistically significant difference were subjected to a receiver operating characteristic (ROC) analysis.ResultsQuantitative anisotropy (qa) values from globus pallidus externus, globus pallidus internus (qa_Gpi), and substantia nigra exhibited significant distributional difference between groups in terms of the improvement rate of UPDRS-3 scale during on-medication (p = 0.003, p = 0.0003, and p = 0.0008, respectively). In ROC analysis, the best parameter in predicting DBS response included qa_Gpi with a cut-off value of 0.01370 achieved an area under the ROC curve, accuracy, sensitivity, and specificity of 0.810, 73%, 62.5%, and 85%, respectively. Optimal cut-off values of ≥ 0.01864 and ≤ 0.01162 yielded a sensitivity and specificity of 100%, respectively.ConclusionThe imaging parameters acquired from GQI, particularly qa_Gpi, may have the ability to non-invasively predict the clinical outcome of DBS surgery.

Intraventricular meningioma resection and visual outcomes.

Intraventricular meningiomas (IVMs) of the lateral ventricle are rare tumors that present surgical challenges because of their deep location. Visual field deficits (VFDs) are one risk associated with these tumors and their treatment. VFDs may be present preoperatively due to the tumor and mass effect (tumor VFDs) or may develop postoperatively due to the surgical approach (surgical VFDs). This institutional series aimed to review surgical outcomes following resection of IVMs, with a focus on VFDs. Patients who received IVM resection at one academic institution between the years 1996 and 2021 were retrospectively reviewed. Diffusion tensor imaging (DTI) reconstructions of the optic radiations around the tumor were performed from preoperative IVM imaging. The VFD course and resolution were documented. Thirty-two adult patients underwent IVM resection, with gross-total resection in 30 patients (93.8%). Preoperatively, tumor VFDs were present in 6 patients, resolving after surgery in 5 patients. Five other patients (without preoperative VFD) had new persistent surgical VFDs postoperatively (5/32, 15.6%) that persisted to the most recent follow-up. Of the 5 patients with persistent surgical VFDs, 4 received a transtemporal approach and 1 received a transparietal approach, and all these deficits occurred prior to regular use of DTI in preoperative imaging. New surgical VFDs are a common neurological deficit after IVM resection. Preoperative DTI may demonstrate distortion of the optic radiations around the tumor, thus revealing safe operative corridors to prevent surgical VFDs.

Experience in treating children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle and systematic review.

To investigate the treatment plan and prognosis of children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle. In this retrospective study, the clinical information of 10 consecutively collected children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle was analyzed. All 10 children underwent pontine tumour resection through a trans-cerebellomedullary fissure approach; 4 children underwent preoperative diffusion tensor imaging scans to determine the relationship between the tumour and facial nerve nucleus, and the other 6 children underwent intraoperative deep electroencephalography (EEG) tumour monitoring, in which the tumour electrical discharge activity of the tumour was recorded. A voxel distribution map was established to describe the distribution of the tumour location, and patient prognosis was evaluated through clinical and imaging follow-up. All 10 children achieved total tumour resection; 9 tumours were pathologically suggested to be ganglioglioma (WHO grade I), and 1 was a hamartoma. The symptoms of the original ocular dyskinesia and hemifacial spasm disappeared immediately after the operation. The children were followed up for 4-75months, and none of the symptoms recurred; four cases with preoperative diffusion tensor imaging showed that the tumour was close to the facial nerve. Four in six intraoperative electrophysiological monitoring showed that the tumour had electrical discharge behaviour, and the tumour distribution map indicates a high density of tumour presence in the facial nerve nucleus and the nucleus of the abducens nerve. In paediatric patients, the facial symptoms are related to the location and abnormal electrical discharge of the tumour. There is no significant correlation between ocular dyskinesia and the location of the tumour. Conventional antiepileptic therapy for this disease is ineffective, and early surgical intervention for total tumour resection can achieve a clinical curative effect.

A diffusion tensor imaging comparison of white matter development in nonsyndromic craniosynostosis to neurotypical infants.

Nonsyndromic craniosynostosis (NSC) is associated with neurocognitive deficits, and intervention at infancy is standard of care to limit the negative effects of NSC on brain development. In this study, diffusion tensor imaging (DTI) was implemented to investigate white matter microstructure in infants with NSC undergoing cranial vault remodeling, and a comparison was made with white matter development in neurotypical controls. Infants presenting with NSC (n = 12) underwent DTI scans before and after cranial vault remodeling. Neurotypical infants (n = 5), age matched to NSC patients at preoperative scans, were compared to preoperative DTI scans. Pre- and postoperative NSC scans were compared in aggregate, and the sagittal synostosis (n = 8) patients were evaluated separately. Finally, neurotypical infants from the University of North Carolina/University of New Mexico Baby Connectome Project (BCP), who underwent DTI scans at timepoints matching the NSC pre- and postoperative DTI scans, were analyzed (n = 9). Trends over the same time period were compared between NSC and BCP scans. No significant differences were found between preoperative NSC scans and controls. White matter development was more limited in NSC patients than in BCP patients, with microstructural parameters of the corpus body and genu and inferior and superior longitudinal fasciculi consistently lagging behind developmental changes observed in healthy patients. Infant white matter development appears more limited in NSC patients undergoing cranial vault remodeling relative to that in neurotypical controls. Further investigation is needed to explore these differences and the specific effects of early surgical intervention.

Correlation Between Pre-Operative Diffusion Tensor Imaging Indices and Post-Operative Outcome in Degenerative Cervical Myelopathy: A Systematic Review and Meta-Analysis.

Systematic review. The correlation between pre-operative diffusion tensor imaging (DTI) metrics and post-operative clinical outcomes in patients with degenerative cervical myelopathy (DCM) has been widely investigated with different studies reporting varied findings. We conducted a systematic review to determine the association between DTI metric and clinical outcomes after surgery. We identified relevant articles that investigated the relationship between pre-operative DTI indices and post-operative outcome in DCM patients by searching PubMed/MEDLINE, Web of Science, Scopus, and EMBASE from inception until October 2023. In addition, quantitative synthesis and meta-analyses were performed. FA was significantly correlated with postoperative JOA or mJOA across all age and follow up subgroups, changes observed in JOA or mJOA from preoperative to postoperative stages (Δ JOA or Δ mJOA) in subgroups aged 65 and above and in those with a follow-up period of 6 months or more, as well as recovery rate in all studies pooled together and also in the under-65 age bracket. Additionally, a significant correlation was demonstrated between recovery rate and ADC across all age groups. No other significant correlations were discovered between DTI parameters (MD, AD, and ADC) and post-operative outcomes. DTI is a quantitative noninvasive evaluation tool that correlates with severity of DCM. However, the current evidence is still elusive regarding whether DTI metric is a validated tool for predicting the degree of post-operative recovery, which could potentially be useful in patient selection for surgery.

Study on the Relationship Between MRI Functional Imaging and Multiple Immunohistochemical Features of Glioma: A Noninvasive and More Precise Glioma Management.

To investigate the performance of diffusion-tensor imaging (DTI) and hydrogen proton magnetic resonance spectroscopy (1H-MRS) parameters in predicting the immunohistochemistry (IHC) biomarkers of glioma. Patients with glioma confirmed by pathology from March 2015 to September 2019 were analyzed, the preoperative DTI and 1H-MRS images were collected, apparent diffusion coefficient (ADC) and fractional anisotropy (FA), in the lesion area were measured, the relative values relative ADC (rADC) and relative FA (rFA) were obtained by the ratio of them in the lesion area to the contralateral normal area. The peak of each metabolite in the lesion area of 1H-MRS image: N-acetylaspartate (NAA), choline (Cho), and creatine (Cr), and metabolite ratio: NAA/Cho, NAA/(Cho + Cr) were selected and calculated. The preoperative IHC data were collected including CD34, Ki-67, p53, S-100, syn, vimentin, NeuN, Nestin, and glial fibrillary acidic protein. One predicting parameter of DTI was screened, the rADC of the Ki-67 positive group was lower than that of the negative group. Two parameters of 1H-MRS were found to have significant reference values for glioma grades, the NAA and Cr decreased as the grade of glioma increased, moreover, Ki-67 Li was negatively correlated with NAA and Cr. NAA and Cr have potential application value in predicting glioma grades and tumor proliferation activity. Only rADC has predictive value for Ki-67 expression among DTI parameters.

White matter tracts contribute selectively to cognitive functioning in patients with glioma.

The functional organization of white matter (WM) tracts is not well characterized, especially in patients with intrinsic brain tumors where complex patterns of tissue injury, compression, and neuroplasticity may be present. This study uses diffusion tensor imaging (DTI) to investigate the relationships between WM tract disruption and cognitive deficits in glioma patients. Seventy-nine patients with glioma underwent preoperative DTI and neuropsychological testing. Thirteen WM tracts were reconstructed bilaterally. Fractional anisotropy and streamline number were obtained for each tract as indices of connectivity. Univariate regression models were used to model the association between WM tract connectivity and neuropsychological outcomes. Glioma patients exhibited variable injury to WM tracts and variable cognitive deficits on validated neuropsychological tests. We identified 16 age-adjusted associations between WM tract integrity and neuropsychological function. The left inferior frontal-occipital fasciculus (IFOF) predicted list learning and dominant-hand fine motor dexterity. The right IFOF predicted non-dominant-hand fine motor dexterity and visuospatial index scores. The left inferior longitudinal fasciculus (ILF) predicted immediate memory list learning and index scores. The right ILF predicted non-dominant-hand fine motor dexterity and backward digit span scores. The left superior longitudinal fasciculus (SLF) I predicted processing speed. The left SLF III predicted list learning, immediate memory index scores, phonemic fluency, and verbal abstract reasoning. The left cingulum predicted processing speed. The right anterior AF predicted verbal abstract reasoning. WM tract disruption predicts cognitive dysfunction in glioma patients. By improving knowledge of WM tract organization, this analysis may guide maximum surgical resection and functional preservation in glioma patients.

Preoperative Diffusion Tensor Imaging in Supratentorial Intra-Axial Brain Tumors: Its Role in Predicting Tumor Histology and Prognosis as well in Surgical Planning and Resection.

Objective There are a large number of prospective studies that use diffusion tensor imaging (DTI) to show the relationship between intracranial tumors and white matter (WM) fibers. We studied the role of DTI in supratentorial intra-axial (ST-IA) tumors of the brain in deciding the surgical approach with maximal resection and minimal or no deficit and in predicting the histological characterization of the tumor and the neurological outcome. Methods A total of 91 cases of ST-IA tumors were included in our study. The neurological status of the patients was assessed preoperatively, and the tumor volume and DTI pattern were noted radiologically. Surgical plan was decided by the senior consultants of the neurosurgery department taking into consideration the findings of tractography and magnetic resonance imaging. The neurological status and the extent of resection were evaluated postoperatively, and the correlation between histopathology with DTI was studied. Results Of the 91 patients, 25 had high-grade glioma (HGG), 60 had low-grade glioma (LGG), and 6 were metastatic lesions. Gross total excisions were done mostly in patients with DTI showing displaced fibers and subtotal/partial resections were done mostly in disrupted/infiltrated tracts, which was statistically significant. The correlation between histopathology and tractography revealed that intact/displaced tracts were seen mostly in LGG (79%), whereas 86% of HGG showed disrupted/infiltrated fibers; both were statistically significant. Conclusion Preoperative DTI in ST-IA brain tumors is an important tool for deciding the appropriate surgical approach for maximal safe resection, thus improving the post-op neurological outcome in patients. It also helps in predicting the tumor histology while also serving as an important prognostication indicator.

Preoperative tractography algorithm for safe resection of tumors located in the descending motor pathways zone.

Diffusion tensor imaging (DTI) tractography facilitates maximal safe resection and optimizes planning to avoid injury during subcortical dissection along descending motor pathways (DMPs). We provide an affordable, safe, and timely algorithm for preoperative DTI motor reconstruction for gliomas adjacent to DMPs. Preoperative DTI reconstructions were extracted from a prospectively acquired registry of glioma resections adjacent to DMPs. The surgeries were performed over a 7-year period. Demographic, clinical, and radiographic data were extracted from patients' electronic medical records. Nineteen patients (12 male) underwent preoperative tractography between January 1, 2013, and May 31, 2020. The average age was 44.5 years (range, 19-81 years). A complete radiological resection was achieved in nine patients, a subtotal resection in five, a partial resection in three, and a biopsy in two. Histopathological diagnoses included 10 patients with high-grade glioma and nine with low-grade glioma. A total of 16 perirolandic locations (10 frontal and six frontoparietal) were recorded, as well as two in the insula and one in the basal ganglia. In 9 patients (47.3%), the lesion was in the dominant hemisphere. The median preoperative and postoperative Karnofsky Performance Scores were 78 and 80, respectively. Motor function was unchanged or improved over time in 15 cases (78.9%). This protocol of DTI reconstruction for glioma removal near the DMP shows good results in low-term neurological functional outcomes.

Predicting Isocitrate Dehydrogenase Mutation Status of Grade 2–4 Gliomas with Diffusion Tensor Imaging (DTI) Parameters Derived from Model-Based DTI and Model-Free Q-Sampling Imaging Reconstructions

To determine whether diffusion tensor imaging (DTI) parameters acquired with model-based DTI and model-free generalized Q-sampling imaging (GQI) reconstructions may noninvasively predict isocitrate dehydrogenase (IDH) mutational status in patients with grade 2-4 gliomas. Forty patients with known IDH genotype (28 IDH wild-type; 12 IDH mutant) who underwent preoperative DTI evaluation on a 3-Tesla magnetic resonance imaging scanner were analyzed retrospectively. Absolute values obtained from model-based and model-free reconstructions were compared. Using the intraclass correlation coefficient, interobserver agreement was assessed for various sampling techniques. Variables having statistically significant distributions between IDH groups were subjected to a receiver operating characteristic (ROC) analysis. Using multivariable logistic regression analysis, independent predictors, if present, were identified and a model was developed. Six imaging parameters (3 from model-based DTI and 3 from model-free GQI reconstructions) showed statistically significant differences between groups (P < 0.001, power >0.97), with very high correlation to each other (P < 0.001). Age difference between the groups was statistically significant (P < 0.001). The optimal logistic regression model comprised a GQI-based parameter and age, which were independent predictors as well, producing an area under the ROC curve, accuracy, sensitivity, and specificity of 0.926, 85%, 75%, and 89.3%, respectively. Using the GQI reconstruction feature alone with a cut-off of 1.60, an 85% of accuracy was also achieved with ROC analysis. The imaging parameters acquired from model-based DTI and model-free GQI reconstructions, combined with the clinical variable age, may have the ability to noninvasively predict the IDH genotype in gliomas, either alone or in particular combinations.

How to combine the use of intraoperative magnetic resonance imaging (MRI) and awake craniotomy for microsurgical resection of hemorrhagic cavernous malformation in eloquent area: a case report

BackgroundCavernous malformations are clusters of abnormal and hyalinized capillaries without interfering brain tissue. Here, we present a cavernous malformation operated under awake conditions, due to location, in an eloquent area and using intraoperative magnetic resonance imaging due to patient’s movement upon the awake phase.Case presentationWe present the pre-, per-, and postoperative course of an inferior parietal cavernous malformation, located in eloquent area, in a 27-year-old right-handed Caucasian male, presenting with intralesional hemorrhage and epilepsy. Preoperative diffusion tensor imaging has shown the cavernous malformation at the interface between the arcuate fasciculus and the inferior fronto-occipital fasciculus. We describe the microsurgical approach, combining preoperative diffusion tensor imaging, neuronavigation, awake microsurgical resection, and intraoperative magnetic resonance imaging.ConclusionComplete microsurgical en bloc resection has been performed and is feasible even in eloquent locations. Intraoperative magnetic resonance imaging was considered an important adjunct, particularly used in this case as the patient moved during the “awake" phase of the surgery and thus neuronavigation was not accurate anymore. Postoperative course was marked by a unique, generalized seizure without any adverse event. Immediate and 3 months postoperative magnetic resonance imaging confirmed the absence of any residue. Pre- and postoperative neuropsychological exams were unremarkable.

A Diffusion Tensor Imaging-Based Prognostic Classification for Surgery of Intrinsic Lesions Involving the Motor Pathways.

The critical role of different adjuncts in improving the neurological outcome in intrinsic brain lesions affecting eloquent areas is demonstrated by their more diffuse utilization. Neurosurgeons often rely on preoperative and intraoperative diffusion tensor imaging tractography to improve the operative strategy and prognosis. We aimed to identify and validate a diffusion tensor imaging-based classification considering the relationship between the brain lesion and the corticospinal tract to predict a >50% reduction of motor evoked potentials (MEPs) during surgical excision of lesions involving the motor pathways. We included patients consecutively enrolled at our institution between April 2020 and September 2022 with 3 patterns of increasing complexity according to the relationship between the lesion and the corticospinal tract as identified on preoperative diffusion tensor imaging. Outcome measures were >50% reduction in intraoperative MEPs and neurological outcome defined as unchanged, improved, or worsened. The study included 83 patients. A statistically significant linear trend between higher rates of reduction of MEPs and higher classification grades was observed (P= 0.001), with sensitivity 0.60, specificity 0.88, accuracy 0.83, and area under the curve 0.75. Higher grades were associated with worse neurological outcomes (P= 0.02). The classification proved reliable in anticipating reduction in intraoperative MEPs and in predicting neurological outcome. Using this classification in patients undergoing surgery for lesions involving the motor pathways could help in counseling the patient, surgical planning, enhancing teamwork of operating room personnel, and improving the patient's prognosis.

160 The Neurosurgical Anatomy of Deficits in Speech Production

INTRODUCTION: Why do similar neurosurgical lesions cause a range of deficits in speech production? We investigated Broca’s aphasia as a disorder of fluency and apraxia of speech (AOS) as a disorder of articulatory coordination to dissociate the anatomy and lesional etiology of these syndromes. METHODS: Patients were prospectively tested with a standardized speech paradigm. Resections were outlined into 3D regions of interest and transformed into a common brainspace (MNI brain). Recordings of speech were retrospectively review by speech language experts to assess apraxia of speech. A voxel-based lesion-mapping (VLSM) algorithm was used to associate resection areas with acute postoperative aphasia or apraxia of speech. Averages of white-matter tracts were overlaid onto MNI reconstructions for analyses of white-matter tract involvement. Pre-operative diffusion tensor imaging reconstructions were created using peri-lesional regions of interest for seeds to investigate perilesional white matter tracts in these cohorts. RESULTS: Of 289 patients with left sided craniotomies and prospective language evaluation, 19 had Broca’s aphasia. 255 of these patients had recordings available for expert review, of whom 28 had apraxia of speech. VLSM analysis found Broca’s aphasia and fluency deficits were not associated with classic anatomic Broca’s area (pars opercularis and triangularis). Rather, they were associated with ventral sensorimotor cortex (SMC) and supramarginal gyrus (P &lt; 0.001). Apraxia of speech was associated the most ventral aspects of SMC (P &lt; 0.001). SLF III reconstructions terminated in the areas associated with Broca’s aphasia and fluency deficits, but had more limited overlap with the VLSM regions associated with apraxia of speech. CONCLUSIONS: Lesions leading to AOS and Broca’s aphasia after neurosurgical resection do not correlate with Broca's area. Rather, they cluster in ventral sensorimotor cortex. Subcortical white-matter tract injury may explain disparate non-fluent aphasia subtypes in patients with anatomically similar lesions.

Can Preoperative Diffusion Tensor Imaging Tractography Predict the Visual Outcomes of Patients with Pituitary Macroadenomas? A Prospective Pilot Study.

Visual impairment has been reported as the most common clinical manifestation of pituitary adenoma (PA) due to the compressive effect of the tumor. This prospective study aimed to evaluate the predictive role of diffusion tensor imaging (DTI) in the visual improvement of patients with PA, who were candidates for endoscopic endonasal surgery. A total of 13 patients (male, 8; female, 5) with visual impairment due to pituitary macroadenoma were enrolled in this study. The DTI findings and visual parameters, including visual acuity (VA), visual field (VF), and visual evoked potential (VEP), were recorded for all participants before and 3months after surgery. Significant recovery was reported in both VA and VF following PA surgery (P < 0.001). The results of perimetry indicated recovery in all quadrants, except for the lower nasal quadrant of the right eye. The tumor volume showed no significant association with the preoperative optic nerve, optic tract, and chiasm fractional anisotropy (FA) or mean diffusivity (MD). The VA and VF recoveries were more likely in patients with a lower preoperative optic nerve MD. Besides, increased preoperative FA of the optic nerve was associated with a higher probability of VA recovery. No significant correlation was found between the optic tract MD and FA values and visual improvement. Overall, MD values below 0.0021 and FA values above 0.1689 could predict a good prognosis of VA recovery after surgery. DTI may have a predictive value in estimating visual improvement in patients with PA preoperatively.

The Prediction of Neurological Prognosis for Cervical Spondylotic Myelopathy Using Diffusion Tensor Imaging.

Although cervical spondylotic myelopathy (CSM) can be easily diagnosed using magnetic resonance imaging (MRI), prediction of surgical effect using preoperative radiological examinations remains difficult. In previous studies, it was reported that diffusion tensor imaging (DTI) may be used for the prediction of surgical effect; however, these studies did not consider the influences of spinal cord compression even though the values of DTI indexes can be distorted by compressive lesions in patients with CSM. Therefore, it is uncertain whether preoperative DTI indexes can actually predict the surgical effect. The aim of this study was to investigate DTI metrics that are hardly affected by spinal cord compression and can accurately predict neurological status after decompressive surgery. Twenty-one patients with CSM who underwent surgery and 10 healthy volunteers were enrolled in this study. The subjects underwent cervical MRI, and values of DTI indexes including axial diffusivity (AD), radial diffusivity (RD), apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were recorded at each intervertebral level. Further, the Japanese Orthopaedic Association (JOA) score of each patient with CSM was recorded before and after surgery for neurological status evaluation. Preoperative and postoperative values of DTI indexes were compared, and correlations between preoperative DTI parameters and postoperative neurological recovery were assessed. After surgery, the lesion-adjacent (LA) ratios of RD and ADC increased (p = 0.04 and p = 0.062, respectively), while the LA ratio of FA decreased (p = 0.075). In contrast, the LA ratio of AD hardly changed. A negative correlation was observed between preoperative LA ratio of AD and JOA recovery rate 6 months after surgery (r = -0.379, p = 0.091). Based on preoperative LA ratio of AD, the patients were divided into a low AD group and a high AD group, and JOA recovery rate 6 months after surgery was found to be higher in the low AD group than in the high AD group (p = 0.024). In patients with CSM, preoperative LA ratio of AD is seldom affected by spinal cord compression, and it negatively correlates with JOA recovery rate 6 months after surgery.

Predictive Value of Preoperative Diffusion Tensor Imaging for Evaluating Postoperative Outcomes of Supratentorial Glioma in the Motor Function Area.

This study aimed to assess the predictive value of preoperative diffusion tensor imaging (DTI) data for surgical outcomes of patients with supratentorial glioma in the motor function area. This is a retrospective study of 43 patients receiving navigation-guided surgery for histopathologically demonstrated supratentorial glioma in the motor function area. All patients underwent preoperative 3 Tesla magnetic resonance imaging examinations with conventional and DTI sequences. Data on preoperative imaging and pre- and postoperative clinical characteristics of patients were retrospectively collected. Univariate and multivariate linear regressions were applied to analyze the relationships between preoperative parameters and pre- and postoperative muscle strength and the Karnofsky Performance Status (KPS) score. Fourteen patients had low-grade gliomas and 29 had high-grade gliomas. Although the corticospinal tract (CST) score did not differ significantly between tumor grades, edema and deviation were common in low-grade gliomas (64.3%), while destroyed and infiltrated lesions were common in high-grade gliomas (58.6%). Muscle strength improved after surgery in the deviated tract group (40%) more than in the infiltrated tract group (33.3%). Two independent indices, preoperative muscle strength (p =0.000) and glioma-to-CST distance (p =0.001), were linearly related to postoperative muscle strength. The preoperative KPS score was the only indicator that affected the postoperative KPS score (p =0.000). DTI should be considered in surgical management of supratentorial gliomas in the motor function area to determine the appropriate surgical strategy and predict the nature of the tumor and postoperative motor function.

Preoperative language tract integrity is a limiting factor in recovery from aphasia after glioma surgery

Aphasia can occur in a broad range of pathological conditions that affect cortical or subcortical structures. Here we test the hypothesis that white matter integrity of language pathways assessed by preoperative diffusion tensor imaging (DTI) is associated with language performance and its recovery after glioma resection. 27 patients with preoperative DTI were included. Segmentation of the arcuate fascicle (AF), the inferior fronto-occipital fascicle (IFOF), the inferior longitudinal fascicle (ILF), the superior longitudinal fascicle (SLF), and the uncinate fascicle (UF) was performed with a fully-connected neural network (FCNN, TractSeg). Median fractional anisotropy (FA) was extracted from the resulting volumes as surrogate marker for white matter integrity and tested for correlation with clinical parameters. After correction for demographic data and multiple testing, preoperative white matter integrity of the IFOF, the ILF, and the UF in the left hemisphere were independently and significantly associated with aphasia three months after surgery. Comparison between patients with and without aphasia three months after surgery revealed significant differences in preoperative white matter integrity of the left AF (p = 0.021), left IFOF (p = 0.015), left ILF (p = 0.003), left SLF (p = 0.001, p = 0.021, p = 0.043 for respective sub-bundles 1–3), left UF (p = 0.041) and the right AF (p = 0.027). Preoperative assessment of white matter integrity of the language network by time-efficient MRI protocols and FCNN-driven segmentation may assist in the evaluation of postoperative rehabilitation potential in glioma patients.

STMO-17 USEFULNESS OF INTEGRATION OF PREOPERATIVE FUNCTIONAL IMAGING AND INTRAOPERATIVE MRI NAVIGATION SYSTEM IN GLIOMA SURGERY

Abstract Purpose Intraoperative magnetic resonance imaging (MRI) update navigation is performed in all cases to preserve neurological function and remove the tumor as much as possible, and to prevent recurrence and improve prognosis. And under awake craniotomy, we supported operators by integrating preoperative functional images with intraoperative MRI. We report our usefulness of image superimposition between medium magnetic field intraoperative MRI and preoperative position emission tomography (PET) and preoperative diffusion tensor imaging (DTI) color-map. Method Of more than 2,200 cases using intraoperative MRI since 2000, 58 preoperative PET (57 methionine and 1 FDG nuclides) superimposed cases (32 left-sided, 35 males, 15 under awake craniotomy, mean 44.8 y.o.) were evaluated. The tumor was located to 34 frontal-, 12 temporal-, 10 parietal lobes, 1 insular gyrus, 1 thalamus. Color-map image superimposition of preoperative DTI (3T, 6-axis application) anisotropic indices in 12 cases (localized in 8 frontal-, 2 insular-, 2 parietal lobes, 7 left-sided, 7 females, mean 35 y.o.). Neurophysiological monitoring was combined (5 under general, 7 awake anesthesia). Results The preoperative TN ratio was 3.8 (in 57 methionine-PET cases), and pathological results (Grade 3-4 in 15-31 cases respectively, out of 54 cases) were used for reliable and preferential removal of sites with higher malignancy and recurrence-prone sites. Recurrent cases (41/58) had altered brain structures that were too difficult to identify without the navigation. In the DTI cases, intraoperative MRI, DTI color-map, and microscopic surgical images were displayed on one screen, and white matter tracts information as a reference is quickly conveyed to operators, and helped to reduce perioperative neurological complications. Conclusion Co-registering an effective superimposition of medium magnetic field intraoperative MRI with high positional accuracy, and preoperative PET- and DTI- images according to the patient's characteristics is currently the most practical navigation application method for intraoperative prediction of important functional information.