Factors affecting the extent of resection and neurological outcomes following transopercular resection of insular gliomas.

BACKGROUND: Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs. METHODS: Retrospective analysis of 66 patients with IG who underwent TO resection was performed. RESULTS: Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable. CONCLUSION: Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM.

Tumor location and neurocognitive function-Unravelling the association and identifying relevant anatomical substrates in intra-axial brain tumors.

Background: Neurocognitive function is a key outcome indicator of therapy in brain tumors. Understanding the underlying anatomical substrates involved in domain function and the pathophysiological basis of dysfunction can help ameliorate the effects of therapy and tailor directed rehabilitative strategies. Methods: Hundred adult diffuse gliomas were co-registered onto a common demographic-specific brain template to create tumor localization maps. Voxel-based lesion symptom (VLSM) technique was used to assign an association between individual voxels and neuropsychological dysfunction in various domains (attention and executive function (A & EF), language, memory, visuospatial/constructive abilities, and visuomotor speed). The probability maps thus generated were further co-registered to cortical and subcortical atlases. A permutation-based statistical testing method was used to evaluate the statistically and clinically significant anatomical parcels associated with domain dysfunction and to create heat maps. Results: Neurocognition was affected in a high proportion of subjects (93%), with A & EF and memory being the most affected domains. Left-sided networks were implicated in patients with A & EF, memory, and language deficits with the perisylvian white matter tracts being the most common across domains. Visuospatial dysfunction was associated with lesions involving the right perisylvian cortical regions, whereas deficits in visuomotor speed were associated with lesions involving primary visual and motor output pathways. Conclusions: Significant baseline neurocognitive deficits are prevalent in gliomas. These are multidomain and the perisylvian network especially on the left side seems to be very important, being implicated in dysfunction of many domains.

An Analysis of Eosinophil- and Basophil-Based Indices in Patients with Glioblastoma and their Correlation with Survival.

BACKGROUND: Glioblastoma (GBM) is the most frequently diagnosed malignant brain tumor in adults. GBM is usually lethal within 24 months of diagnosis, despite aggressive multimodality treatment. Although it has been established that cancer-related inflammation is associated with worse outcomes, the role of eosinophils, basophils, atopy, and allergy in glioma biology is only gradually being delineated. In this study, we aimed to examine if eosinophil-based and basophil-based indices were altered in patients with GBM compared with healthy controls. We also aimed to study if there was any correlation between these indices and patient-related and tumor-related factors and survival. METHODS: This study was a retrospective analysis of prospectively maintained databases. Data pertaining to patient-related and tumor-related factors, hemograms, and survival data were obtained from the electronic medical records of selected patients. Correlations between eosinophil-based and basophil-based indices and these factors were studied, as was the association with overall survival. RESULTS: All the indices were altered in patients with GBM compared with normal healthy controls. The absolute eosinophil count was higher and the neutrophils/eosinophils ratio was lower in the better prognosis groups: those with better performance status; those without features of increased intracranial pressure or altered sensorium at presentation; those with ATRX-retained tumors that did not overexpress p53; and in the long-term survivors. The total lymphocyte count/basophils ratio and the absolute eosinophil count both independently predicted survival in a multivariate analysis. CONCLUSIONS: The absolute eosinophil count was consistently higher in the better prognosis groups and is likely to be incorporated into prognostic models for GBM.

Transopercular Approach to Resection of Dominant Hemisphere Diffuse Insular Glioma Using Multimodal Intraoperative Strategy with Awake Mapping.

Background: Deep location as well as relation to major vascular structures and eloquent brain areas make insular glioma resection challenging. Transsylvian and transopercular approaches have been described for resection of these tumors. Objective: We illustrate the anatomical relations of a dominant hemisphere insular glioma and present the video demonstrating the step-wise resection of the same via frontal transopercular approach. Surgical Procedure: A 27-year-old lady with dominant hemisphere insular glioma underwent awake surgery through a transopercular approach with cortical and subcortical mapping using direct electrical stimulation for resection of the same. Result: Gross total resection of left insular glioma was achieved without any fresh postoperative deficits. Conclusion: Awake transopercular approach with intraoperative motor, language, and neuropsychological monitoring helps achieve maximum safe resection of insular glioma in the dominant cerebral hemisphere.

Development of a Standardized Semantic Feature-Based Reporting Proforma for Intraoperative Ultrasound Findings in Brain Tumors and Application in High-Grade Gliomas - A Preliminary Study.

Purpose A semantic feature-based reporting proforma for intraoperative ultrasound findings in brain tumors was devised to standardize reporting. It was applied as a pilot study on a cohort of histologically confirmed high-grade supratentorial gliomas (Grade 3 and 4) for internal validation. Materials and Methods This intraoperative semantic ultrasound proforma was used to evaluate 3D ultrasound volumes using Radiant DICOM software by 3 surgeons. The ultrasound semantic features were correlated with histological features like tumor grade, IDH status, and MIB index. Results 68 patients were analyzed using the semantic proforma. Irregular crenated was the most common margin (63.2%) and lesions were heterogeneously hyperechoic (95.6%). Necrosis was commonly seen and noted as single (67.6%) or multiple (13.2%) in over 80% cases. A separate perilesional zone, which was predominantly hyperechoic in 41.8% and both hypo and hyperechoic in 12.7%, could be identified in 54.5% of cases. Grade 4 tumors were more likely to have an irregular crenated margin (71.2%) with a single large area of necrosis, while Grade 3 tumors were likely to have smooth (31.3%) or non-characterizable margins (31.2%) with no or multiple areas of necrosis. IDH-negative tumors were more likely to have a single large focus of necrosis. Among the GBMs (52 cases), MIB labelling index of>15% was associated with poorly delineated, uncharacterizable margins, when compared with MIB labelling index<15% (23.5 vs. 0%), (p=0.046). Conclusion A detailed semantic proforma was developed for brain tumors and was internally validated. A few ultrasound sematic features were identified correlating with histological features in high-grade gliomas. It will require further external validation for refinement and acceptability.

Analysis of Factors Associated with Long-Term Survival in Patients with Glioblastoma.

BACKGROUND: Some patients with glioblastoma multiforme (GBM) survive 3-5 years (or longer) after diagnosis. The goal of this study was to identify differences between the long-term survivors (LTS) and those who had a shorter overall survival (non-LTS groups). METHODS: This study was a retrospective analysis of prospectively maintained surgical databases. All patients who underwent safe maximal resection for GBM were included. Demographic, clinical, radiologic, and pathologic data were obtained from electronic medical records. Values of the biomarkers of systemic inflammation were computed from the preoperative hemogram reports. Patients with an overall survival (OS) ≥36 months were defined as the LTS group and were compared with the non-LTS groups (OS<36 months). RESULTS: Patients in the LTS group were younger, had a better baseline performance status, and were more likely to have undergone near- or gross-total resection. LTS was associated with lower Ki67 labeling, MGMT methylation, IDH mutation, and lack of p53 overexpression. Several novel findings were generated by this study. A longer pretreatment duration of symptoms was associated with a longer OS. Higher pretreatment levels of the absolute neutrophil count, neutrophil-lymphocyte ratio, monocyte-lymphocyte ratio, derived neutrophil-lymphocyte ratio and systemic index of inflammation, and lower levels of the absolute eosinophil count and eosinophil-lymphocyte ratio all correlated with a shorter OS. CONCLUSIONS: Several differences were identified between the LTS and non-LTS groups. These differences will likely be incorporated into future prognostic models. They may also aid in differentiation between recurrent disease and treatment-related changes.

Comparison of outcomes of free-hand 2-dimensional ultrasound-guided versus navigated 3-dimensional ultrasound-guided biopsy for supratentorial tumours: a single-institution experience with 125 cases.

PURPOSE: The purpose of this study was to evaluate the relative utility and benefits of free-hand 2-dimensional intraoperative ultrasound (FUS) and navigated 3-dimensional intraoperative ultrasound (NUS) as ultrasound-guided biopsy (USGB) techniques for supratentorial lesions. METHODS: All patients who underwent USGB for suspected supratentorial tumours from January 2008 to December 2017 were retrospectively analyzed. The charts and electronic medical records of these patients were studied. Demographic, surgical, and pathological variables were collected and analyzed. The study group consisted of patients who underwent either FUS or NUS for biopsy. RESULTS: A total of 125 patients (112 adults and 13 children) underwent USGB during the study period (89 FUS and 36 NUS). NUS was used more often for deep-seated lesions (58% vs. 18% for FUS, P<0.001). The mean operating time for NUS was longer than for FUS (156 minutes vs. 124 minutes, P=0.001). Representative yield was found in 97.7% of biopsies using FUS and in 100% of biopsies using NUS (diagnostic yield, 93.6% and 91.3%, respectively). The majority of lesions (89%) were high-grade gliomas or lymphomas. Postoperative complications were more common in the NUS group (8.3% vs. 1.2%), but were related to the tumour location (deep). CONCLUSION: Despite the longer operating time and higher rate of postoperative complications, NUS has the benefit of being suitable for biopsies of deep-seated supratentorial lesions, while FUS remains valuable for superficial lesions.

Non-enhancing gliomas: does intraoperative ultrasonography improve resections?

PURPOSE: Non-enhancing diffuse gliomas are a challenging surgical proposition. Delineation of tumour extent on preoperative imaging and intraoperative visualization are often difficult. METHODS: We retrospectively analyzed all cases of non-enhancing gliomas that were operated on using navigated 3-dimensional ultrasonography (US). Tumour delineation (good, moderate, or poor) on preoperative magnetic resonance imaging (MRI) and intraoperative US was compared. Post-resection US findings with respect to residual tumour status were compared to the postoperative imaging findings. The extent of resection was calculated and recorded. RESULTS: There were 55 gliomas (43 high-grade, 12 low-grade). Forty were close to eloquent areas. The pre-resection concordance of MRI with US was 56%, with US defining more tumours as well-delineated (n=26) than MRI (n=13). US was used for resection control in 50 cases. Gross tumour resection was achieved in 24 cases (51%). US correctly predicted the residual tumour status in 78% of cases. The use of US led to radical resections even in some tumours preoperatively deemed to be unresectable. However, eloquent location was the only independent predictor of the extent of resection. CONCLUSION: Intraoperative US is a useful tool for guiding resection of non-enhancing gliomas. It may be better than MRI for delineating these tumours, and may thereby facilitate improved resection of these otherwise poorly delineated tumours. However, functional boundaries remain the main limiting factor for achieving complete resection of non-enhancing gliomas.

Molecular features unique to glioblastoma radiation resistant residual cells may affect patient outcome - a short report.

PURPOSE: Previously we have shown, using a primary glioblastoma (GBM) cell model, that a subpopulation of innately radiation resistant (RR) GBM cells survive radiotherapy and form multinucleated and giant cells (MNGCs) by homotypic fusions. We also showed that MNGCs may cause relapse. Here, we set out to explore whether molecular characteristics of RR cells captured from patient-derived primary GBM cultures bear clinical relevance. METHODS: Primary cultures were derived from 19 naive GBM tumor samples. RR cells generated from these cultures were characterized using various cell biological assays. We also collected clinicopathological data of the 19 patients and assessed associations with RR variables using Spearman's correlation test and with patient survival using Kaplan-Meier analysis. Significance was determined using a log-rank test. RESULTS: We found that SF2 (surviving fraction 2) values (p = 0.029), days of RR cell formation (p = 0.019) and percentage of giant cells (p = 0.034) in the RR population independently correlated with a poor patient survival. We also found that low ATM (Ataxia-telangiectasia mutated) expression levels in RR cells showed a significant (p = 0.002) negative correlation with SF2 values. A low ATM expression level in RR cells along with a high tumor volume was also found to negatively correlate with patient survival (p = 0.011). Finally, we found that the ATM expression levels in RR cells independently correlated with a poor patient survival (p = 0.014). CONCLUSIONS: Our data indicate that molecular features of innately radiation resistant GBM cells independently correlate with clinical outcome. Our study also highlights the relevance of using patient-derived primary GBM cultures for the characterization of RR cells that are otherwise inaccessible for analysis.

What you see and what you don't - Utility and pitfalls during fluorescence guided resections of gliomas using 5-aminolevulinic acid.

BACKGROUND: Fluorescence guided resections have been increasingly used for malignant gliomas. Despite the high reliability of the technique, there remain some practical limitations. METHODS: We retrospectively reviewed our experience with 50 consecutive cases of 5-aminolevulinic acid (ALA)-guided resections. Clinico-radiological features and intraoperative variables (pattern and type of fluorescence) were recorded. In a subset (12 cases), we performed annotated biopsies to calculate the diagnostic accuracy of the technique. We recorded and analysed the patterns of excision and residual fluorescence and correlated this with postoperative magnetic resonance imaging (MRI). RESULTS: Majority of the tumours (92%) were resectable and predominantly enhancing. Though strong fluorescence was seen in most of them, there were 2 cases with a non-enhancing tumor which showed fluorescence. Visualized strong fluorescence had a very high predictive value (100%) for detecting the pathological tissue. However, it was not always possible to resect all the fluorescing tissue. Proximity to critical neuro-vascular structures was the commonest reason for failure to achieve a gross total excision (16 cases). Additionally, there were some cases (5 of 8) where the non-fluorescing residue was resected intraoperatively with the help of ultrasound. Despite the presence of residual fluorescence, overall radiological gross total resection was achieved in 66% cases. CONCLUSIONS: ALA guided resections are very useful in malignant gliomas, even if these lesions do not enhance signi cantly. Although ALA reliably depicts the tumour intraoperatively, it may not be possible to resect all this tissue completely. Additionally, non-fluorescing tumor may be completely missed out and may require additional imaging tools. Working within the limitations of the technique and using complementary modalities (ultrasound or brain mapping) may be ideal for achieving a radical resection of malignant gliomas.

Surgery for brain metastases: An analysis of outcomes and factors affecting survival.

OBJECTIVES: For patients who develop brain metastases from solid tumors, age, KPS, primary tumor status and presence of extracranial metastases have been identified as prognostic factors. However, the factors that affect survival in patients who are deemed fit to undergo resection of brain metastases have not been clearly elucidated hitherto. PATIENTS AND METHODS: This is a retrospective analysis of a prospectively maintained database. All patients who underwent resection of intracranial metastases from solid tumors were included. Various patient, disease and treatment related factors were analyzed to assess their impact on survival. RESULTS: Overall, 124 patients had undergone surgery for brain metastases from various primary sites. The median age and pre-operative performance score were 53 years and 80 respectively. Synchronous metastases were resected in 17.7% of the patients. The postoperative morbidity and mortality rates were 17.7% and 2.4% respectively. Adjuvant whole brain radiation was received by 64 patients. At last follow-up, 8.1% of patients had fresh post-surgical neurologic deficits. The median progression free and overall survival were 6.91 was 8.56 months respectively. CONCLUSIONS: Surgical resection of for brain metastases should be considered in carefully selected patients. Gross total resection and receiving adjuvant whole brain RT significantly improves survival in these patients.

Resection of Pediatric Brain Tumors: Intraoperative Ultrasound Revisited.

BACKGROUND: Extent of resection is a very important prognostic marker in most pediatric brain tumors. Intraoperative imaging facilitates resection control. Intraoperative ultrasound (IOUS) is a cost-effective alternative to intraoperative magnetic resonance, but scant literature addresses its utility in this context. METHODS: We retrospectively reviewed all pediatric brain tumors operated at our center using navigated three-dimensional ultrasound (US). The utility of the US in resection control was recorded and extent of resection evaluated. RESULTS: IOUS was used in 20 cases (3 for frameless biopsy and 17 for tumor resection control). It was 100% accurate in localizing all tumors and yielded 100% diagnosis in the biopsy cases. Technical limitations precluded its use in 2 of the 17 cases of tumor resection. In the remaining 15, it correctly predicted the residual tumor status in 13 cases (87%). A gross total resection was achieved overall in 12 cases (80%) with postoperative morbidity in only one case. CONCLUSIONS: IOUS is a useful tool to localize intracranial tumors and guide the resection reliably. Widespread use can improve its applicability and make it an effective intraoperative imaging tool in pediatric brain tumors.

Periventricular glioblastomas and ependymal involvement interrogated using intraoperative fluorescence - a pathological correlative study.

RATIONALE: Subventricular zone (SVZ) involvement has been proposed as an adverse prognostic factor in glioblastomas (GBM). The true extent of ventricular involvement at surgery is often difficult to establish and is poorly studied. Tumour fluorescence provides us with an exciting opportunity to interrogate tumour extent intraoperatively. METHODS: We conducted a retrospective analysis of all cases of GBMs operated using aminolevulinic acid-induced fluorescence and analyzed radiological SVZ involvement alongwith the incidence of ventricular entry at surgery, ependymal fluorescence and histological correlation of the ependymal involvement. RESULTS: Of 30 GBMs, radiological SVZ involvement was seen in 26 of which ventricles were opened at surgery in 19. Diffuse ependymal fluorescence was seen in 10 of the 19 cases (51%) and histology revealed tumour infiltration in only one of the five cases where ependymal tissue was sampled. Focal ependymal fluorescence seen in two of the 19 cases was always pathological. Diffuse ependymal fluorescence did not always correlate with gross appearance of the ventricular lining at surgery. Nor did it correlate with SVZ involvement. CONCLUSIONS: Pathological significance of diffusely fluorescing ependymal lining seen during surgery is questionable and need not represent tumour extension. Ependymal fluorescence may sometimes not be visualized even when the tumour appears to involve the SVZ. These results highlight the potential limitations of fluorescence especially in the bordering infiltrating zone where its predictive value is diminished.

Psammomatoid Juvenile Ossifying Fibroma: Report of Three Cases with a Review of Literature.

Psammomatoid juvenile ossifying fibroma (PJOF), a variant of juvenile ossifying fibroma (JOF), is a locally aggressive neoplasm of the children and young adults. This entity has predilection for the sinonasal region. It forms a differential diagnosis for many bone neoplasms. We report three cases of PJOF, in young patients whose biopsy showed the presence of psammomatoid bodies in a cellular fibrous stroma. The diagnosis of JOF indicates requirement of extensive surgery due to its locally aggressive nature.

Intraoperative Ultrasound Technology in Neuro-Oncology Practice-Current Role and Future Applications.

BACKGROUND: Surgery for cranial and spinal tumors has evolved tremendously over the years. Not only have neuro-oncologists been able to better understand tumor biology and thereby improve multimodality therapy, but advances in surgical techniques have also directly equipped neurosurgeons with the armamentarium necessary to achieve more radical resections safely. Intraoperative imaging tools are one such adjunct. Though intraoperative magnetic resonance (MR) has emerged as the "gold standard" among these, logistical challenges make it difficult to implement across all centers. On the other hand, the use of ultrasound (US) intraoperatively predates the use of MR. Over the past 4 decades, technologic improvements have refined and expanded the scope and application of intraoperative US technology. Strategies to maximize its efficacy and overcome the various limitations have evolved. A large volume of clinical experience has accumulated with respect to its role as an adjunct specifically in tumor surgery. METHODS: We performed a literature review to evaluate the role of IOUS in tumor surgery. This review traces the evolution of intraoperative US over the years and reviews the current scope and applications with respect to neuro-oncologic surgery, as well as potential future applications. RESULTS: IOUS has evolved over the years since its introduction. Advances in technology have provided real-time navigated and 3-D techniques, which overcome many of the limitations of older IOUS techniques. This has shown to be very useful in not only localization of lesions, but also in improving resection rates as well as survival. CONCLUSIONS: IOUS is a powerful and versatile multipurpose intraoperative adjunct in tumor surgery, especially for resection control. The learning curve is relatively easy to climb and future improvements in technology are likely to widen the scope of its use.

Direct navigated 3D ultrasound for resection of brain tumors: a useful tool for intraoperative image guidance.

OBJECTIVE: Navigated 3D ultrasound is a novel intraoperative imaging adjunct permitting quick real-time updates to facilitate tumor resection. Image quality continues to improve and is currently sufficient to allow use of navigated ultrasound (NUS) as a stand-alone modality for intraoperative guidance without the need for preoperative MRI. METHODS: The authors retrospectively analyzed cases involving operations performed at their institution in which a 3D ultrasound navigation system was used for control of resection of brain tumors in a "direct" 3D ultrasound mode, without preoperative MRI guidance. The usefulness of the ultrasound and its correlation with postoperative imaging were evaluated. RESULTS: Ultrasound was used for resection control in 81 cases. In 53 of these 81 cases, at least 1 intermediate scan (range 1-3 intermediate scans) was obtained during the course of the resection, and in 50 of these 53 cases, the result prompted further resection. In the remaining 28 cases, intermediate scans were not performed either because the first ultrasound scan performed after resection was interpreted as showing no residual tumor (n = 18) and resection was terminated or because the surgeon intentionally terminated the resection prematurely due to the infiltrative nature of the tumor and extension of disease into eloquent areas (n = 10) and the final ultrasound scan was interpreted as showing residual disease. In an additional 20 cases, ultrasound navigation was used primarily for localization and not for resection control, making the total number of NUS cases where radical resection was planned 101. Gross-total resection (GTR) was planned in 68 of these 101 cases and cytoreduction in 33. Ultrasound-defined GTR was achieved in 51 (75%) of the cases in which GTR was planned. In the remaining 17, further resection had to be terminated (despite evidence of residual tumor on ultrasound) because of diffuse infiltration or proximity to eloquent areas. Of the 33 cases planned for cytoreduction, NUS guidance facilitated ultrasound-defined GTR in 4 cases. Overall, ultrasound-defined GTR was achieved in 50% of cases (55 of 111). Based on the postoperative imaging (MRI in most cases), GTR was achieved in 58 cases (53%). Final (postresection) ultrasonography was documented in 78 cases. The findings were compared with the postoperative imaging to ascertain concordance in detecting residual tumor. Overall concordance was seen in 64 cases (82.5%), positive concordance was seen in 33 (42.5%), and negative in 31 (40%). Discordance was seen in 14 cases-with ultrasound yielding false-positive results in 7 cases and false-negative results in 7 cases. Postoperative neurological worsening occurred in 15 cases (13.5%), and in most of these cases, it was reversible by the time of discharge. CONCLUSIONS: The results of this study demonstrate that 3D ultrasound can be effectively used as a stand-alone navigation modality during the resection of brain tumors. The ability to provide repeated, high-quality intraoperative updates is useful for guiding resection. Attention to image acquisition technique and experience can significantly increase the quality of images, thereby improving the overall utility of this modality.

Navigated intraoperative ultrasound for resection of gliomas: Predictive value, influence on resection and survival.

BACKGROUND: Navigable ultrasound (NUS) is a useful adjunct for controlling resection in intra-axial brain tumors. We investigated its role in predicting residual disease and thereby in influencing the intraoperative decision regarding additional resection as also its influence on survival in glioblastoma patients. METHODS: A prospectively maintained database was accessed to retrieve the data regarding consecutive histologically verified gliomas operated using the NUS. We documented the number of times US images were obtained, the surgeon's impression of each scan and the subsequent decision regarding further resection. Survival (progression-free and overall) was calculated for patients with a glioblastoma, and univariate and multivariate analyses performed. RESULTS: The NUS was used for resection control in 88 gliomas. In 66 cases, intermediate scans were performed resulting in further resection in 60 of them. Radiological gross total resection was obtained in 46 cases (44%). The US correctly predicted postoperative residue in 83% cases (sensitivity and specificity of 87 and 78% respectively; positive and negative predictive values of 82 and 84%). There were 9 false positives and 6 false negative cases. When the US was false positive, the resolution was more often good (7 of 9 cases); whereas when there were false negatives, it was more likely to be less than optimal (4 of 6). Morbidity was 17% and this was not related to the additional resections. In the subset of glioblastoma patients (n = 28) use of NUS was associated with significantly better progression-free as well as overall survival rates. CONCLUSIONS: NUS is a useful intraoperative adjunct in controlling resections. It positively and decisively influences the intraoperative course of the surgery. Understanding its correct technique and limitations, along with experience in image interpretation can help in maximizing its accuracy without compromising functional outcomes. Optimally utilized, it can improve survival.

δ-Aminolevulinic acid-induced fluorescence-guided resection of brain tumors.

Maximal resection of gliomas is the current standard of care. Various technical adjuncts facilitate this. Aminolevulinic acid (ALA)-induced fluorescence guided resection (FGR) is one such strategy. We review the current literature related to ALA FGR. It is based on the selective uptake of ALA into glioma cells and its preferential conversion to protoporphyrin IX. This selectivity provides a high positive predictive value for ALA induced fluorescence. Since the introduction of this technique, clinical experience supports its efficacy in improving resections in malignant gliomas when compared to other contemporary intraoperative imaging strategies such as the magnetic resonance imaging (MRI) or the adjuncts that exhibit passive permeability like fluorescein. Future research into the understanding of the basis of ALA metabolism in glioma cells and advances in visualization technology will potentially improve the scope of application of this technique.