High-field iMRI in glioblastoma surgery: improvement of resection radicality and survival for the patient?

Awake Craniotomy for Tumor Resection: Further Optimizing Therapy of Brain Tumors

In recent years more and more data have emerged linking the most radical resection to prolonged survival in patients harboring brain tumors. Since total tumor resection could increase postoperative morbidity, many methods have been suggested to reduce the risk of postoperative neurological deficits: awake craniotomy with the possibility of continuous patient-surgeon communication is one of the possibilities of finding out how radical a tumor resection can possibly be without causing permanent harm to the patient.In 1994 we started to perform awake craniotomy for glioma resection. In 2005 the use of intraoperative high-field magnetic resonance imaging (MRI) was included in the standard tumor therapy protocol. Here we review our experience in performing awake surgery for gliomas, gained in 219 patients.Patient selection by the operating surgeon and a neuropsychologist is of primary importance: the patient should feel as if they are part of the surgical team fighting against the tumor. The patient will undergo extensive neuropsychological testing, functional MRI, and fiber tractography in order to define the relationship between the tumor and the functionally relevant brain areas. Attention needs to be given at which particular time during surgery the intraoperative MRI is performed. Results from part of our series (without and with ioMRI scan) are presented.

Optimization of tumor resection with intra-operative magnetic resonance imaging

Intra-operative MRI (ioMRI) may be used to optimize tumor resection. Utilization of this technology allows for the removal of residual tumor mass following initial tumor removal, maximizing the extent of resection. This, in turn, has been shown to lead to improved outcomes. Individual studies have examined the impact of ioMRI on the rate of extended resection, but a comprehensive review of this topic is needed. A literature review of the MEDLINE, EMBASE, CENTRAL, and Google Scholar databases revealed 12 eligible studies. This included 804 primary operations and 238 extended resections based on ioMRI findings. Use of ioMRI led to extended tumor resection in 13.3-54.8% of patients (mean 37.3%). Stratification by tumor type showed additional resection occurred, on average, in 39.1% of glioma resections (range 13.3-70.0%), 23.5% of pituitary tumor resections (range 13.3-33.7%), and 35.0% of nonspecific tumor resections (range 17.5-40%). Tumor type (glioma vs. pituitary) did not significantly influence the rate of further excision following ioMRI (p=0.309). There was no difference in secondary resection rate between studies limited to pediatric patients and those including adults (p=0.646). Thus, the use of intra-operative MRI frequently results in further resection of tumors. It is primarily used for the resection of gliomas and pituitary tumors. Tumor type does not appear to be a significant contributing factor to the rate of secondary tumor removal. Limited evidence suggests that extended resection may translate into improved clinical outcomes and mortality rates. However, results have not been unanimous, while clinical effect sizes have often been modest.

Resection of C6 gliomas in rats with the aid of the waterjet technique

OBJECTIVES

While clinically the safety and efficacy of waterjet resection of brain tumors have been shown, evidence that waterjet dissection improves tumor resection radicality in comparison with conventional techniques is still missing. In the present study, resection radicality and tumor-free long-term survival of both techniques were evaluated in a C6-glioma model.

MATERIAL AND METHODS

Fifty-thousand C6-glioma cells were stereotactically transplanted in the left frontal lobe of 100 male Sprague-Dawley rats. After MRI-scanning for evaluation of tumor extension, microsurgical tumor resection was performed with conventional techniques (n=50) or with the waterjet dissector at pressures of 6bar (n=50). Twenty-five animals of each group were sacrificed after surgery for histological analysis. For analysis of survival after tumor resection, twenty-five animals of each group were followed-up to analyze tumor-free survival using the Kaplan Meier method.

RESULTS

In the waterjet group, the resection cavity was free of C6-tumor cells in 10/25 (40%) rats showing a trend (p=0.3) towards better resection radicality compared to the rats that were treated conventionally (7/10; 28%). R1-resection with up to 250C6 cells/object slice was found in 14/25 (56%) rats after waterjet dissection compared to 6/25 (24%) rats treated conventionally showing significance (p<0.01). Probability of survival was 38% after 2 weeks and 20% after 6 months in the waterjet group compared to 30% and 16% respectively in the conventional group. Diffuse tumor cell spreading with possible influence on survival was shown in 47/50 rats.

CONCLUSION

In this experimental model, waterjet tumor resection did reveal significantly better resection radicality compared to the conventional technique. Although a direct transfer of these results to human glioma surgery is prohibited, the waterjet technique might contribute to the best possible resection radicality in human gliomas. Nevertheless, tumor cell spreading remains a major problem. Further studies have to address that the surgical results - in deed - improve the postoperative outcome.

Current trends in the surgical management and treatment of adult glioblastoma

This manuscript discusses the current surgical management of glioblastoma. This paper highlights the common pathophysiology attributes of glioblastoma, surgical options for diagnosis/treatment, current thoughts of extent of resection (EOR) of tumor, and post-operative (neo)adjuvant treatment. Glioblastoma is not a disease that can be cured with surgery alone, however safely performed maximal surgical resection is shown to significantly increase progression free and overall survival while maximizing quality of life. Upon invariable tumor recurrence, re-resection also is shown to impact survival in a select group of patients. As adjuvant therapy continues to improve survival, the role of surgical resection in the treatment of glioblastoma looks to be further defined.

A new functional classification system (FGA/B) with prognostic value for glioma patients

Despite advances in multimodal treatments, malignant gliomas remain characterized by a short survival time. Surgical treatment is accepted to be the first line of therapy, with recent studies revealing that maximal possible tumor reduction exerts significant impact on patient outcome. Consideration of tumor localization in relation to functionally eloquent brain areas has been gaining increasing importance. Despite existing assessment methods, the availability of a simple but reliable preoperative grading based on functional data would therefore prove to be indispensable for the prediction of postoperative outcome and hence for overall survival in glioma patients. We performed a clinical investigation comprising 322 patients with gliomas and developed a novel classification system of preoperative tumor status, which considers tumor operability based on two graduations (Friedlein Grading - FG): FGA with lesions at safe distance to eloquent regions which can be completely resected, and FGB referring to tumors which can only be partially resected or biopsied. Investigation of outcome revealed that FGA were characterized by a significantly longer overall survival time compared to FGB. We offer the opportunity to classify brain tumors in a dependable and reproducible manner. The FGA/B grading method provides high prognostic value with respect to overall survival time in relation to the extent of location-dependent tumor resection.

Incidentalomas to glioblastoma multiforme

In April 1999, a 25-year-old male underwent magnetic resonance imaging (MRI) as a control subject for a multiple sclerosis study. The scan serendipitously revealed two lesions (‘incidentalomas’) in the right frontal lobe. Initially, he was asymptomatic and was monitored with interval MRI scans. After years of monitoring, contact was accidentally lost. He later presented following a witnessed generalized seizure. He was commenced on phenytoin, which was changed to carbamazepine due to side effects. MRI revealed three gliomas and an open brain biopsy confirmed a diagnosis of low-grade astrocytoma. The location and multifocal nature of the gliomas ruled out complete neurosurgical debulking. However, his seizures increased in frequency and in February 2007, the biopsy confirmed malignant transformation to multifocal glioblastoma multiforme. He successfully underwent partial debulking, radiotherapy and adjuvant temozolomide chemotherapy. Currently, he is 6 years post-treatment and asymptomatic.

Study of freshly excised brain tissues using terahertz imaging

We demonstrated that tumors in freshly excised whole brain tissue could be differentiated clearly from normal brain tissue using a reflection-type terahertz (THz) imaging system. THz binary images of brain tissues with tumors indicated that the tumor boundaries in the THz images corresponded well to those in visible images. Grey and white-matter regions were distinguishable owing to the different distribution of myelin in the brain tissue. THz images corresponded closely with magnetic resonance imaging (MRI) results. The MRI and hematoxylin and eosin-stained microscopic images were investigated to account for the intensity differences in the THz images for fresh and paraffin-embedded brain tissue. Our results indicated that the THz signals corresponded to the cell density when water was removed. Thus, THz imaging could be used as a tool for label-free and real-time imaging of brain tumors, which would be helpful for physicians to determine tumor margins during brain surgery.

Through the patient's eyes: an emphasis on patient-centered values in operative decision making in the management of malignant glioma

The Joint Section on Tumors of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons is now in its 30th year. In many ways its growth and development has paralleled neurosurgery and medicine as a whole. This is most evident in our endeavor towards more patient-centered care and focus on quantity and quality of life. As the push towards evidence-based care continues, it is important to ensure that individualized care remains a guiding principle. Conscientious surgeons continue to refine techniques and develop technologies that push the boundaries of surgical efficacy while better defining the risks of surgery and the impacts of surgical complications. This article provides a review of the factors involved in minimizing risk and obtaining maximal outcomes for patients through insightful patient selection and evidence-based surgical decision-making. Herein, we present the philosophy and practice of the Hermelin Brain Tumor Center at the Henry Ford Health System as one type of approach to caring for the patient with a malignant glioma.

THE APPLICATION OF NANOMATERIALS IN DIAGNOSIS AND TREATMENT FOR MALIGNANT PRIMARY BRAIN TUMORS

Malignant primary brain tumors have a very high morbidity and mortality. Even though enormous advances have been made in primary brain tumor management, in the case of malignant primary brain tumors, current diagnostic strategies cannot identify exact infiltrating margins, surgery alone cannot achieve total mass resection, and adjuvant therapies cannot improve survivals. Therefore, there is an urgent need to explore novel strategies to diagnose and treat such infiltrating brain tumors. Nanomaterials, particularly zero-dimensional and one-dimensional platforms, can carry various compounds such as contrast agents, anticancer drugs and genes into brain tumor cells specifically. Thus, contrast agent-based nanomaterials can selectively present infiltrating tumor outlines, while anticancer agent-based nanomaterials can specifically kill malignant tumor cells. In addition, dual-targeting nanomaterials, multifunctional nanocarriers, theranostic nanovehicles as well as convection-enhanced delivery technology hold promise to increase drug accumulation in tumor tissues, which could largely improve anticancer efficacy. In this review, we will mainly focus on the application of nanomaterials in preoperative diagnosis, intraoperative diagnosis and adjuvant treatment for malignant primary brain tumors.

Usefulness of three-dimensional navigable intraoperative ultrasound in resection of brain tumors with a special emphasis on malignant gliomas

BACKGROUND

Intraoperative imaging is increasingly being used in resection of brain tumors. Navigable three-dimensional (3D)-ultrasound is a novel tool for planning and guiding such resections. We review our experience with this system and analyze our initial results, especially with respect to malignant gliomas.

METHODS

A prospective database for all patients undergoing sononavigation-guided surgery at our center since this surgery's introduction in June 2011 was queried to retrieve clinical data and technical parameters. Imaging was reviewed to categorize tumors based on enhancement and resectability. Extent of resection was also assessed.

RESULTS

Ninety cases were operated and included in this analysis, 75 % being gliomas. The 3D ultrasound mode was used in 87 % cases (alone in 40, and combined in 38 cases). Use of combined mode function [ultrasound (US) with magnetic resonance (MR) images] facilitated orientation of anatomical data. Intraoperative power Doppler angiography was used in one-third of the cases, and was extremely beneficial in delineating the vascular anatomy in real-time. Mean duration of surgery was 4.4 hours. Image resolution was good or moderate in about 88 % cases. The use of the intraoperative imaging prompted further resection in 59 % cases. In the malignant gliomas (51 cases), gross-total resection was achieved in 47 % cases, increasing to 88 % in the "resectable" subgroup.

CONCLUSIONS

Navigable 3D US is a versatile, useful and reliable intraoperative imaging tool in resection of brain tumors, especially in resource-constrained settings where Intraoperative MR (IOMR) is not available. It has multiple functionalities that can be tailored to suit the procedure and the experience of the surgeon.

Surgical resection of malignant gliomas-role in optimizing patient outcome

Malignant gliomas represent one of the most devastating human diseases. Primary treatment of these tumours involves surgery to achieve tumour debulking, followed by a multimodal regimen of radiotherapy and chemotherapy. Survival time in patients with malignant glioma has modestly increased in recent years owing to advances in surgical and intraoperative imaging techniques, as well as the systematic implementation of randomized trial-based protocols and biomarker-based stratification of patients. The role and importance of several clinical and molecular factors-such as age, Karnofsky score, and genetic and epigenetic status-that have predictive value with regard to postsurgical outcome has also been identified. By contrast, the effect of the extent of glioma resection on patient outcome has received little attention, with an 'all or nothing' approach to tumour removal still taken in surgical practice. Recent studies, however, reveal that maximal possible cytoreduction without incurring neurological deficits has critical prognostic value for patient outcome and survival. Here, we evaluate state-of-the-art surgical procedures that are used in management of malignant glioma, with a focus on assessment criteria and value of tumour reduction. We highlight key surgical factors that enable optimization of adjuvant treatment to enhance patient quality of life and improve life expectancy.

Aminolevulinic acid (ALA)-protoporphyrin IX fluorescence guided tumour resection. Part 1: Clinical, radiological and pathological studies

The intraoperative identification and resection of glioma is a significant and important challenge in neurosurgery. Complete resection of the enhancing tumour increases the median survival time in glioblastoma compared to partial glioma resection; however, it is achieved in fewer than half of eligible patients when conventional tumour identification methods are used. Increasing the incidence of complete resection, without causing excess morbidity, requires new methods to accurately identify neoplastic tissue intraoperatively, such as use of the drug 5-amino-levulinic acid (ALA). After ALA ingestion, the fluorescent molecule protoporphyrin IX (PpIX) accumulates in high grade glioma, allowing the neurosurgeon to more easily detect and accurately resect tumour. The utility of ALA has been demonstrated in a large, multicentre phase III randomised control trial of 243 patients with high grade glioma. ALA use led to a significant increase in the incidence of complete resection (65% compared to 36%), improved progression-free survival at 6 months (41% compared to 21%), fewer reinterventions, and delayed onset of neurological deterioration. This review provides a broad assessment of ALA-PpIX fluorescence-guided resection, with Part 1 focusing on its clinical efficacy, and correlations with imaging and histology. The theoretical, biochemical and practical aspects of ALA use are reviewed in Part 2.

Nanotechnology applications for glioblastoma

Glioblastoma remains one of the most difficult cancers to treat and represents the most common primary malignancy of the brain. Although conventional treatments have found modest success in reducing the initial tumor burden, infiltrating cancer cells beyond the main mass are responsible for tumor recurrence and ultimate patient demise. Targeting residual infiltrating cancer cells requires the development of new treatment strategies. The emerging field of cancer nanotechnology holds promise in the use of multifunctional nanoparticles for imaging and targeted therapy of glioblastoma. This article examines the current state of nanotechnology in the treatment of glioblastoma and directions of further study.

Intraoperative image guidance in neurosurgery: development, current indications, and future trends

Introduction. As minimally invasive surgery becomes the standard of care in neurosurgery, it is imperative that surgeons become skilled in the use of image-guided techniques. The development of image-guided neurosurgery represents a substantial improvement in the microsurgical treatment of tumors, vascular malformations, and other intracranial lesions. Objective. There have been numerous advances in neurosurgery which have aided the neurosurgeon to achieve accurate removal of pathological tissue with minimal disruption of surrounding healthy neuronal matter including the development of microsurgical, endoscopic, and endovascular techniques. Neuronavigation systems and intraoperative imaging should improve success in cranial neurosurgery. Additional functional imaging modalities such as PET, SPECT, DTI (for fiber tracking), and fMRI can now be used in order to reduce neurological deficits resulting from surgery; however the positive long-term effect remains questionable for many indications. Method. PubMed database search using the search term "image guided neurosurgery." More than 1400 articles were published during the last 25 years. The abstracts were scanned for prospective comparative trials. Results and Conclusion. 14 comparative trials are published. To date significant data amount show advantages in intraoperative accuracy influencing the perioperative morbidity and long-term outcome only for cerebral glioma surgery.

Magnetic nanoparticles: an emerging technology for malignant brain tumor imaging and therapy

Magnetic nanoparticles (MNPs) represent a promising nanomaterial for the targeted therapy and imaging of malignant brain tumors. Conjugation of peptides or antibodies to the surface of MNPs allows direct targeting of the tumor cell surface and potential disruption of active signaling pathways present in tumor cells. Delivery of nanoparticles to malignant brain tumors represents a formidable challenge due to the presence of the blood-brain barrier and infiltrating cancer cells in the normal brain. Newer strategies permit better delivery of MNPs systemically and by direct convection-enhanced delivery to the brain. Completion of a human clinical trial involving direct injection of MNPs into recurrent malignant brain tumors for thermotherapy has established their feasibility, safety and efficacy in patients. Future translational studies are in progress to understand the promising impact of MNPs in the treatment of malignant brain tumors.