SUPRAMAX-study: supramaximal resection versus maximal resection for glioblastoma patients: study protocol for an international multicentre prospective cohort study (ENCRAM 2201)

INTRODUCTION

A greater extent of resection of the contrast-enhancing (CE) tumour part has been associated with improved outcomes in glioblastoma. Recent results suggest that resection of the non-contrast-enhancing (NCE) part might yield even better survival outcomes (supramaximal resection, SMR). Therefore, this study evaluates the efficacy and safety of SMR with and without mapping techniques in high-grade glioma (HGG) patients in terms of survival, functional, neurological, cognitive and quality of life outcomes. Furthermore, it evaluates which patients benefit the most from SMR, and how they could be identified preoperatively.

METHODS AND ANALYSIS

This study is an international, multicentre, prospective, two-arm cohort study of observational nature. Consecutive glioblastoma patients will be operated with SMR or maximal resection at a 1:1 ratio. Primary endpoints are (1) overall survival and (2) proportion of patients with National Institute of Health Stroke Scale deterioration at 6 weeks, 3 months and 6 months postoperatively. Secondary endpoints are (1) residual CE and NCE tumour volume on postoperative T1-contrast and FLAIR (Fluid-attenuated inversion recovery) MRI scans; (2) progression-free survival; (3) receipt of adjuvant therapy with chemotherapy and radiotherapy; and (4) quality of life at 6 weeks, 3 months and 6 months postoperatively. The total duration of the study is 5 years. Patient inclusion is 4 years, follow-up is 1 year.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Ethics Committee (METC Zuid-West Holland/Erasmus Medical Center; MEC-2020-0812). The results will be published in peer-reviewed academic journals and disseminated to patient organisations and media.

Cognition and health-related quality of life in long-term survivors of high-grade glioma: an interactive perspective from patient and caregiver

BACKGROUND

The health-related quality of life (HRQoL) and cognition are important indicators for the quality of survival in patients with high-grade glioma (HGG). However, data on long-term survivors and their caregivers are scarce. We aim to investigate the interaction between cognition and HRQoL in long-term survivors, their caregivers' evaluations, and the effect on caregiver strain and burden.

METHODS

21 long-term HGG (8 WHO grade III and 13 WHO grade IV) survivors (survival ≥ 5 years) and 15 caregivers were included. Cognition (verbal memory, attention, executive functioning, and language), HRQoL, anxiety and depression, caregiver strain, and caregiver burden were assessed with standardized measures. Questionnaires were completed by patients and/or their caregivers.

RESULTS

Mean survival was 12 years (grade III) and 8 years (grade IV). Cognition was significantly impaired with a large individual variety. Patients' general HRQoL was not impaired but all functioning scales were deviant. Patient-proxy agreement was found in most HRQoL subscales. Three patients (14%) showed indications of anxiety or depression. One-third of the caregivers reported a high caregiver strain or a high burden. Test scores for attention, executive functioning, language, and/or verbal memory were correlated with perceived global health status, cognitive functioning, and/or communication deficits. Caregiver burden was not related to cognitive deficits.

CONCLUSIONS

In long-term HGG survivors maintained HRQoL seems possible even when cognition is impaired in a large variety at the individual level. A tailored approach is therefore recommended to investigate the cognitive impairments and HRQoL in patients and the need for patient and caregiver support.

Human brain mapping using co-registered fUS, fMRI and ESM during awake brain surgeries: A proof-of-concept study

Accurate, depth-resolved functional imaging is key in both understanding and treatment of the human brain. A new sonography-based imaging technique named functional Ultrasound (fUS) uniquely combines high sensitivity with submillimeter-subsecond spatiotemporal resolution available in large fields-of-view. In this proof-of-concept study we show that: (A) fUS reveals the same eloquent regions as found by fMRI while concomitantly visualizing in-vivo microvascular morphology underlying these functional hemodynamics and (B) fUS-based functional maps are confirmed by Electrocortical Stimulation Mapping (ESM), the current gold-standard in awake neurosurgical practice. This unique cross-modality experiment was performed using motor, visual and language-related functional tasks in patients undergoing awake brain tumor resection. The current work serves as an important milestone towards further maturity of fUS as well as a novel avenue to increase our understanding of hemodynamics-based functional brain imaging.

The ScreeLing: Detecting Semantic, Phonological, and Syntactic Deficits in the Clinical Subtypes of Frontotemporal and Alzheimer's Dementia

The ScreeLing is a screening instrument developed to assess post-stroke aphasia, via the linguistic levels Syntax, Phonology, and Semantics. It could also be a useful test for the clinical subtypes of frontotemporal dementia (FTD) and Alzheimer's dementia (AD), as specific and often selective disorders are expected. Its ability to differentiate between the clinical subtypes of FTD and AD is, however, still unknown. We investigated differences in ScreeLing total and subscores, linguistic-level disorders' relationship with disease severity, and classification abilities, in patients with behavioral variant FTD (bvFTD; n = 46), patients with primary progressive aphasia (PPA; n = 105) (semantic variant primary progressive aphasia [svPPA], non-fluent variant primary progressive aphasia [nfvPPA], and logopenic variant primary progressive aphasia [lvPPA], AD [n = 20] and controls [n = 35]). We examined group differences in ScreeLing total and subscores, and one-, two- or three-level linguistic disorders using one-way analyses of covariance (ANCOVAs) or Quade's rank ANCOVA. We used frequency analyses to obtain the occurrence of the linguistic-level disorders. We determined sensitivity and specificity by the area under the curve by receiver-operating characteristics analyses to investigate classification abilities. The total score was lower in patients (bvFTD: 63.8 ± 8.5, svPPA: 58.8 ± 11.3, nfvPPA: 63.5 ± 8.4, lvPPA: 61.7 ± 6.6, AD: 63.8 ± 5.5) than controls (71.3 ± 1.0) (p < .001). Syntax subscores were lower in svPPA (19.4 ± 4.6; p < .001) and lvPPA (20.3 ± 3.2; p = .002) than controls (23.8 ± 0.4). Phonology subscores were lower in lvPPA (19.8 ± 2.6) than bvFTD (21.7 ± 2.8) (p = .010). Semantics subscores were lowest in svPPA (17.8 ± 5.0; p < .002). A selective phonological disorder was most prevalent in lvPPA (34.9%). The higher the disease severity, the more linguistic-level disorders. The optimal cutoff for the total score was 70, and 23 for all three subscores. Good classification abilities were found for the Semantics (svPPA vs. bvFTD), Phonology (lvPPA vs. svPPA), and Syntax (nfvPPA vs. lvPPA) subscores. This easy to administer test gives information about language processing with the potential to improve differential diagnosis in memory clinics and in the future potentially also clinical trial planning.

Neuropsychiatric adverse effects of synthetic glucocorticoids: A systematic review and meta-analysis

BACKGROUND

Synthetic glucocorticoids are widely used among patients suffering from a wide range of diseases. Glucocorticoids are very efficacious, but can be accompanied by neuropsychiatric adverse effects. This systematic review and meta-analysis assesses and quantifies the proportion of different neuropsychiatric adverse effects in patients using synthetic glucocorticoids.

METHODS

Six electronic databases were searched to identify potentially relevant studies. Randomized controlled trials, cohort and cross-sectional studies assessing psychiatric side effects of glucocorticoids measured with validated questionnaires were eligible. Risk of bias was assessed with RoB 2, ROBINS-I, and AXIS appraisal tool. For proportions of neuropsychiatric outcomes, we pooled proportions, and when possible, differences in questionnaire scores between glucocorticoid users and non-users were expressed as standardized mean differences (SMD). Data were pooled in a random-effects logistic regression model.

RESULTS

We included 49 studies with heterogeneity in study populations, type, dose, and duration of glucocorticoids. For glucocorticoid users, meta-analysis showed a proportion of 22% for depression (95%CI 14%-33%), 11% for mania (95%CI 2%-46%), 8% for anxiety (95%CI 2%-25%), 16% for delirium (95%CI 6%-36%), and 52% for behavioural changes (95%CI 42%-61%). Questionnaire scores for depression (SMD of 0.80 (95%CI 0.35-1.26)), and mania (0.78 (95%CI 0.14-1.42)) were higher than in controls, indicating more depressive and manic symptoms following glucocorticoid use.

CONCLUSIONS

The heterogeneity of glucocorticoid use is reflected in the available studies. Despite this heterogeneity, the proportion of neuropsychiatric adverse effects in glucocorticoid users is high. The most substantial associations with glucocorticoid use were found for depression and mania. Upon starting glucocorticoid treatment, awareness of possible psychiatric side effects is essential. More structured studies on incidence and potential pathways of neuropsychiatric side effects of prescribed glucocorticoids are clearly needed.

Longitudinal changes in qualitative aspects of semantic fluency in presymptomatic and prodromal genetic frontotemporal dementia

BACKGROUND

The semantic fluency test is one of the most widely used neuropsychological tests in dementia diagnosis. Research utilizing the qualitative, psycholinguistic information embedded in its output is currently underexplored in presymptomatic and prodromal genetic FTD.

METHODS

Presymptomatic MAPT (n = 20) and GRN (n = 43) mutation carriers, and controls (n = 55) underwent up to 6 years of neuropsychological assessment, including the semantic fluency test. Ten mutation carriers became symptomatic (phenoconverters). Total score and five qualitative fluency measures (lexical frequency, age of acquisition, number of clusters, cluster size, number of switches) were calculated. We used multilevel linear regression modeling to investigate longitudinal decline. We assessed the co-correlation of the qualitative measures at each time point with principal component analysis. We explored associations with cognitive decline and grey matter atrophy using partial correlations, and investigated classification abilities using binary logistic regression.

RESULTS

The interrater reliability of the qualitative measures was good (ICC = 0.75-0.90). There was strong co-correlation between lexical frequency and age of acquisition, and between clustering and switching. At least 4 years pre-phenoconversion, GRN phenoconverters had fewer but larger clusters (p < 0.001), and fewer switches (p = 0.004), correlating with lower executive function (r = 0.87-0.98). Fewer switches was predictive of phenoconversion, correctly classifying 90.3%. Starting at least 4 years pre-phenoconversion, MAPT phenoconverters demonstrated an increase in lexical frequency (p = 0.009) and a decline in age of acquisition (p = 0.034), correlating with lower semantic processing (r = 0.90). Smaller cluster size was predictive of phenoconversion, correctly classifying 89.3%. Increase in lexical frequency and decline in age of acquisition were associated with grey matter volume loss of predominantly temporal areas, while decline in the number of clusters, cluster size, and switches correlated with grey matter volume loss of predominantly frontal areas.

CONCLUSIONS

Qualitative aspects of semantic fluency could give insight into the underlying mechanisms as to why the "traditional" total score declines in the different FTD mutations. However, the qualitative measures currently demonstrate more fluctuation than the total score, the measure that seems to most reliably deteriorate with time. Replication in a larger sample of FTD phenoconverters is warranted to identify if qualitative measures could be sensitive cognitive biomarkers to identify and track mutation carriers converting to the symptomatic stage of FTD.

Impact of maximal extent of resection on postoperative deficits, patient functioning and survival within clinically important glioblastoma subgroups

Background

The impact of extent of resection (EOR), residual tumor volume (RTV), and gross-total resection (GTR) in glioblastoma subgroups is currently unknown. This study aimed to analyze their impact in patient subgroups in relation to neurological and functional outcomes.

Methods

Patients with tumor resection for eloquent glioblastoma between 2010 and 2020 at four tertiary centers were recruited from a cohort of 3919 patients.

Results

One thousand and forty-seven (1047) patients were included. Higher EOR and lower RTV were significantly associated with improved OS and PFS across all subgroups, but RTV was a stronger prognostic factor. GTR based on RTV improved median OS in the overall cohort (19.0 months, p&lt;0.0001), and in the subgroups with IDH wildtype tumors (18.5 months, p=0.00055), MGMT methylated tumors (35.0 months, p&lt;0.0001), aged &lt;70 (20.0 months, p&lt;0.0001), NIHSS 0-1 (19.0 months, p=0.0038), KPS 90-100 (19.5 months, p=0.0012), and KPS ≤ 80 (17.0 months, p=0.036). GTR was significantly associated with improved OS in the overall cohort (HR 0.58, p=0.0070) and improved PFS in the NIHSS 0-1 subgroup (HR 0.47, p=0.012). GTR combined with preservation of neurological function (OFO 1 grade) yielded the longest survival times (median OS 22.0 months, p &lt;0.0001), which was significantly more frequently achieved in the awake mapping group (50.0%) than in the asleep group (21.8%) (p&lt;0.0001).

Conclusions

Maximum resection was especially beneficial in the subgroups aged &lt;70, NIHSS 0-1, and KPS 90-100 without increasing the risk of postoperative NIHSS or KPS worsening. These findings may assist surgical decision making in individual glioblastoma patients.

P01.12.B Analysis of semi-spontaneous speech before, during and after awake craniotomy: a case study

Background

The standard treatment for patients with eloquent gliomas is awake craniotomy (AC) with direct electrical stimulation, which results in a larger extent of resection while maintaining language function. Intraoperative language monitoring includes different standardized tasks and spontaneous speech elicitation. Despite careful monitoring, it was found that spontaneous speech deteriorated long-term after surgery. However, intraoperative spontaneous speech has not been investigated before. Detailed analyses may reveal possible predictors for language outcome. For the first time, we present a case study in which we investigate and quantify semi-spontaneous speech before, during and after AC.

Material and Methods

A left-handed 50-year old male with a glioblastoma (WHO grade 4) in the left parietal lobe underwent AC. Semi-spontaneous speech was collected (audio/video recording) using the Sabadel story retelling task at: 1 day before (T1), during (T2), 2 days (T3) and 2 months (T4) after surgery. Recordings were manually transcribed and language errors were quantified. A preliminary acoustic analysis with simple automatic peak detection was performed. Comparisons between test moments were made.

Results

Manual transcription showed 1) notable changes in the number of paraphasias (T1: 1% - T2: 1% - T3: 9% - T4: 5%), interjections (T1: 9% - T2: 9% - T3: 15% - T4: 10%), minimal utterances (T1: 4% - T2: 4% - T3: 6% - T4: 1%), false starts (T1: 3% - T2: 5% - T3: 6% - T4: 8%), self-corrections (T1: 3% - T2: 2% - T3: 4% - T4: 7%) and 2) small changes in repetitions (T1: 1% - T2: 0% - T3: 2% - T4: 3%), hesitations (T1: 1% - T2: 0% - T3: 2% - T4: 0%), incomplete sentences (T1: 1% - T2: 0% - T3: 0% - T4: 1%), grammatical errors (T1: 2% - T2: 1% - T3: 2% - T4: 2%). The total number of words (T1: 273 - T2: 283 - T3: 249 - T4: 287) and utterances (T1: 39 - T2: 41 - T3: 36 - T4: 34) varied slightly. Acoustic analysis showed a slight increase in word length during and directly after surgery but it recovered to preoperative level on the long-term (T1: .66 s - T2: .75 s - T3: .87 s - T4: .69 s).

Conclusion

The semi-spontaneous speech task in this case study was sensitive to capture changes in perioperative language status. Paraphasias, interjections, minimal utterances, hesitations and word length increased directly after surgery followed by a decrease 2 months later. This is a frequently reported pattern of transient language deficits. However, other errors (false starts, repetitions, self-corrections, incomplete sentences) increased at 2 months after surgery, indicating longer term language deficits. Future exploration of both the acoustic analysis, which shows potential for real-time feedback, and the manual transcriptions, could possibly lead to a better understanding of intra- and postoperative language performance as a prognostic factor for long-term language outcome, with possible implications for language therapy.

The DEXA-CORT trial: study protocol of a randomised placebo-controlled trial of hydrocortisone in patients with brain tumour on the prevention of neuropsychiatric adverse effects caused by perioperative dexamethasone

Introduction

The synthetic glucocorticoid dexamethasone can induce serious neuropsychiatric adverse effects. Dexamethasone activates the glucocorticoid receptor (GR) but, unlike endogenous cortisol, not the mineralocorticoid receptor (MR). Moreover, dexamethasone suppresses cortisol production, thereby eliminating its MR binding. Consequently, GR overactivation combined with MR underactivation may contribute to the neuropsychiatric adverse effects of dexamethasone. The DEXA-CORT trial aims to reactivate the MR using cortisol to reduce neuropsychiatric adverse effects of dexamethasone treatment.

Methods and analysis

The DEXA-CORT study is a multicentre, randomised, double-blind, placebo-controlled trial in adult patients who undergo elective brain tumour resection treated perioperatively with high doses of dexamethasone to minimise cerebral oedema. 180 patients are randomised between treatment with either two times per day 10 mg hydrocortisone or placebo during dexamethasone treatment. The primary study outcome is the difference in proportion of patients scoring ≥3 points on at least one of the Brief Psychiatric Rating Scale (BPRS) questions 5 days postoperatively or earlier at discharge. Secondary outcomes are neuropsychiatric symptoms, quality of sleep, health-related quality of life and neurocognitive functioning at several time points postoperatively. Furthermore, neuropsychiatric history, serious adverse events, prescribed (psychiatric) medication and referrals or evaluations of psychiatrist/psychologist and laboratory measurements are assessed.

Ethics and dissemination

The study protocol has been approved by the Medical Research Ethics Committee of the Leiden University Medical Center, and by the Dutch competent authority, and by the Institutional Review Boards of the participating sites. It is an investigator-initiated study with financial support by The Netherlands Organisation for Health Research and Development (ZonMw) and the Dutch Brain Foundation. Results of the study will be submitted for publication in a peer-reviewed journal.

Trial registration number

NL6726 (Netherlands Trial Register); open for patient inclusion. EudraCT number 2017-003705-17.

OS09.6.A Cognition and health-related quality of life in long time survivors of high-grade glioma

BACKGROUND

Although prognosis is poor in high-grade glioma (HGG) patients, some become a long-term survivor (LTS). Health-related quality of life (HRQOL) and cognition are seen as indicators for quality of survival in HGG but data in LTS and their caregivers are scarce. We aim to investigate cognition and HRQOL in LTS with evaluation by their proxies.

MATERIAL AND METHODS

We included LTS with initial HGG-diagnosis between 1999–2014. Cognition was assessed with: Boston Naming Test, shortened Token Test, verbal (Category and Letter) Fluency, Diagnostic Instrument of Mild Aphasia, Hopkins Verbal Learning Test and Trail Making Test (A, B, B/A) and HRQOL with: EORTC Quality of Life Questionnaire (C30) and Brain Cancer Module (BN20). 15 Proxies evaluated patients’ HRQOL with: C30, BN20 and they filled in a burden scale: Caregiver Strain Index (CSI).

RESULTS

21 patients with grade III or IV glioma and 7 years (range 5–20 years) median survival after diagnosis participated. Compared to normative data patients deviated significantly on HVLT (direct recall, delayed recall, recognition true positives), TMT (A, B and B/A), BNT and CF (p&lt;0.05) which was not affected by hemispheric localization (left/right) or tumor grade (III/IV). HVLT delayed recall was significantly worse in patients with &gt;12 years survival compared to patients with &lt;12 years survival. Average QoL rating in patients was 75%, proxy’s evaluation about patients’ QoL was similar. Moderate correlations (p&lt;0.05) were found between impaired scores on TMT and CF and C30 cognition subscale and between impaired scores on CF, HVLT delayed recall and BNT and BN20 language subscale. At individual level only one patient had intact scores on all administered tests. Other patients had mild impairments on 1–5 subtests and severe impairment on 1–8 subtests. Five out of 14 (36%) proxies reported a great level of caregiver strain on CSI.

CONCLUSION

Most LTS suffer from cognitive impairments. Despite worse prognosis and cognitive impairments, at group level patients report relatively intact QoL, which is supported by their proxies. However, at the individual level severity of impairments is variable and high caregiver strain is reported in one-third of the proxies. Objective cognitive functioning was only modestly associated with subjective experience in patients. A patient-tailored approach is recommended to investigate individual impairments and needs for rehabilitation and support for patients and also for their carers.

P09.03 Fully integrating functional Ultrasound (fUS) into the onco-neurosurgical operating room: Towards a new real-time, high-resolution image-guided resection tool with multimodal potential

BACKGROUND

Onco-neurosurgical practice still relies heavily on pre-operatively acquired images to guide intra-operative decision-making for safe tumor removal, a practice with inherent pitfalls such as registration inaccuracy due to brain shift, and lack of real-time (functional) feedback. Exploiting the opportunity for real-time imaging of the exposed brain can improve intra-operative decision-making, neurosurgical safety and patient outcomes. Previously, we described functional Ultrasound (fUS) as a high-resolution, depth-resolved imaging technique able to detect functional regions and vascular morphology during awake resections. Here, we present for the first time fUS as a fully integrated, MRI/CT-registered imaging modality in the OR.

MATERIAL AND METHODS

fUS relies on high-frame-rate (HFR) ultrasound, making the technique sensitive for very small motions caused by vascular dynamics (µDoppler) and allowing measurements of changes in cerebral blood volume (CBV) with micrometer-millisecond precision. This opens up the possibility to 1) detect functional response, as CBV-changes reflect changes in metabolism of activated neurons through neurovascular coupling and 2) visualize in-vivo vascular morphology of tumor and healthy tissue. During a range of anesthetized and awake onco-neurosurgical procedures we acquired images of brain and spinal cord using conventional linear ultrasound probes connected to an experimental acquisition unit. Building on Brainlab’s ‘Cranial Navigation’ and ‘Intra-Operative Ultrasound’ modules, we could co-register our intra-operative Power Doppler Images (PDIs) to patient-registered MRI/CT-data. Using the ‘IGTLink’ research interface, we could access and store real-time tracking data for informed volume reconstructions in post-processing.

RESULTS

Intra-operative fUS could be registered to MRI/CT-images in real-time, showing overlays of PDIs at imaging depths of &gt;5 centimeters. During meningioma resections, these co-registered PDIs revealed fUS’ ability to visualize the tumor’s feeding vessels and surrounding healthy vasculature prior to durotomy, with a level of detail unprecedented by conventional MRI-sequences. Comparing post-operatively reconstructed 3D-vascular maps of pre- and post-durotomy acquisitions, further confirmed the dural dependency of the vascular network feeding the tumor. During awake resections, fUS revealed distinct functional areas as activated during motor and language tasks.

CONCLUSION

fUS is a new real-time, high-resolution and depth-resolved imaging technique, combining characteristics uniquely beneficial for a potential image-guided resection tool. The successful integration of fUS in the onco-neurosurgical OR demonstrated by our team, is an essential step towards clinical integration of fUS, as well as the technique’s validation against modalities such as MRI and CT.

eHealth cognitive rehabilitation for brain tumor patients: results of a randomized controlled trial

BACKGROUND

Evidence-based cognitive rehabilitation programs for brain tumor patients are not widely available, despite the high need. We aimed to evaluate the effects of a tablet-based cognitive rehabilitation program on cognitive performance, cognitive complaints, fatigue, and psychological distress in primary brain tumor patients following neurosurgery. Also, attrition, adherence and patient satisfaction with the program were evaluated.

METHODS

Adults with presumed low-grade glioma and meningioma were recruited before surgery. Three months thereafter, participants were allocated to the intervention group or waiting-list control group using minimization. The 10-week eHealth app ReMind, based on the effective face-to-face intervention, consisted of psychoeducation, strategy-training and attention retraining. Performance-based cognitive outcomes and patient-reported outcomes were assessed before surgery and 3, 6 and 12 months thereafter. Mean scores, percentages of cognitively impaired individuals and reliable change indices (RCIs) were compared between groups.

RESULTS

Sixty-two out of 183 eligible patients were randomized. Of the people who declined, 56% reported that participation would to be too burdensome. All participants found a tablet-app suitable for delivery of cognitive rehabilitation and 90% rated the program as "good" or "excellent". Performance-based cognitive outcomes and patient-reported outcomes did not significantly differ in group means over time nor RCIs between the intervention (final n = 20) and control group (final n = 25).

CONCLUSIONS

Recruitment at this early stage was difficult, resulting in limited statistical power. No significant effects were demonstrated, while adherence and satisfaction with the eHealth program were good. In clinical practice, ReMind may be helpful, if timing would be adapted to patients' needs.

NIMG-19. USING FUNCTIONAL ULTRASOUND (FUS) TO MAP BRAIN FUNCTIONALITY AND TUMOR VASCULATURE WITH MICROMETER-MILLISECOND PRECISION

OBJECTIVE

In the early 20th century, Dr. Cushing first demonstrated the use of electrical stimulation mapping (ESM) to define motor and sensory cortices during neurosurgical procedures. Essentially, little has changed in what guides a neurosurgeon’s intra-operative decision-making since. Inherent limitations of ESM such as limited depth penetration and risk of seizure elicitation, warrant the development of new image-guided resection tools. Here, we present functional Ultrasound (fUS)-imaging as a new, high-resolution tool to guide intra-operative decision-making during awake tumor removal.

METHODS

fUS relies on high-frame-rate ultrasound, which offers images at thousands of frames-per-second. As such, fUS is sensitive to very small motions caused by vascular dynamics (µDoppler), allowing measurements of changes in cerebral blood volume (CBV). This facilitates the possibility to 1) detect functional response, as CBV-changes reflect changes in metabolism of activated neurons through neurovascular coupling and 2) visualize high-resolution vascular morphology of tumor and healthy tissue. During conventional awake craniotomy surgery, n= 10 patients were asked to perform 60s functional tasks to elicit cortical responses. Simultaneously, a conventional 5 MHz ultrasound probe connected to an experimental acquisition system, was placed over ESM-defined functional areas. After image acquisition, correlation analyses with the corresponding tasks revealed functional and non-functional areas. In addition, 3D vascular maps were reconstructed from subsequent 2D-Power Doppler Images (PDIs).

RESULTS

fUS was able to detect functional areas as activated using conventional motor tasks, as well as complex language-related tasks. In addition, both 2D-PDIs and 3D-reconstructions revealed the ability of fUS to detect unique high-resolution onco-vascular characteristics in high- and low-grade malignancies. In all cases, images were acquired with micrometer-millisecond (300 µm, 1.5-2.0 msec) precision at imaging depths &gt; 5 cm.

CONCLUSIONS

Applying fUS-imaging successfully in this awake craniotomy series serves as a clear demonstration of the technique’s revolutionary potential for maximizing safe tumor removal.

Functional Ultrasound (fUS) During Awake Brain Surgery: The Clinical Potential of Intra-Operative Functional and Vascular Brain Mapping

Background and Purpose

Oncological neurosurgery relies heavily on making continuous, intra-operative tumor-brain delineations based on image-guidance. Limitations of currently available imaging techniques call for the development of real-time image-guided resection tools, which allow for reliable functional and anatomical information in an intra-operative setting. Functional ultrasound (fUS), is a new mobile neuro-imaging tool with unprecedented spatiotemporal resolution, which allows for the detection of small changes in blood dynamics that reflect changes in metabolic activity of activated neurons through neurovascular coupling. We have applied fUS during conventional awake brain surgery to determine its clinical potential for both intra-operative functional and vascular brain mapping, with the ultimate aim of achieving maximum safe tumor resection.

Methods

During awake brain surgery, fUS was used to image tumor vasculature and task-evoked brain activation with electrocortical stimulation mapping (ESM) as a gold standard. For functional imaging, patients were presented with motor, language or visual tasks, while the probe was placed over (ESM-defined) functional brain areas. For tumor vascular imaging, tumor tissue (pre-resection) and tumor resection cavity (post-resection) were imaged by moving the hand-held probe along a continuous trajectory over the regions of interest.

Results

A total of 10 patients were included, with predominantly intra-parenchymal frontal and temporal lobe tumors of both low and higher histopathological grades. fUS was able to detect (ESM-defined) functional areas deep inside the brain for a range of functional tasks including language processing. Brain tissue could be imaged at a spatial and temporal resolution of 300 μm and 1.5-2.0 ms respectively, revealing real-time tumor-specific, and healthy vascular characteristics.

Conclusion

The current study presents the potential of applying fUS during awake brain surgery. We illustrate the relevance of fUS for awake brain surgery based on its ability to capture both task-evoked functional cortical responses as well as differences in vascular characteristics between tumor and healthy tissue. As current neurosurgical practice is still pre-dominantly leaning on inherently limited pre-operative imaging techniques for tumor resection-guidance, fUS enters the scene as a promising alternative that is both anatomically and physiologically informative.