Hyperspectral imaging benchmark based on machine learning for intraoperative brain tumour detection.

Brain surgery is one of the most common and effective treatments for brain tumour. However, neurosurgeons face the challenge of determining the boundaries of the tumour to achieve maximum resection, while avoiding damage to normal tissue that may cause neurological sequelae to patients. Hyperspectral (HS) imaging (HSI) has shown remarkable results as a diagnostic tool for tumour detection in different medical applications. In this work, we demonstrate, with a robust k-fold cross-validation approach, that HSI combined with the proposed processing framework is a promising intraoperative tool for in-vivo identification and delineation of brain tumours, including both primary (high-grade and low-grade) and secondary tumours. Analysis of the in-vivo brain database, consisting of 61 HS images from 34 different patients, achieve a highest median macro F1-Score result of 70.2 ± 7.9% on the test set using both spectral and spatial information. Here, we provide a benchmark based on machine learning for further developments in the field of in-vivo brain tumour detection and delineation using hyperspectral imaging to be used as a real-time decision support tool during neurosurgical workflows.

VNIR-NIR hyperspectral imaging fusion targeting intraoperative brain cancer detection.

Currently, intraoperative guidance tools used for brain tumor resection assistance during surgery have several limitations. Hyperspectral (HS) imaging is arising as a novel imaging technique that could offer new capabilities to delineate brain tumor tissue in surgical-time. However, the HS acquisition systems have some limitations regarding spatial and spectral resolution depending on the spectral range to be captured. Image fusion techniques combine information from different sensors to obtain an HS cube with improved spatial and spectral resolution. This paper describes the contributions to HS image fusion using two push-broom HS cameras, covering the visual and near-infrared (VNIR) [400-1000 nm] and near-infrared (NIR) [900-1700 nm] spectral ranges, which are integrated into an intraoperative HS acquisition system developed to delineate brain tumor tissue during neurosurgical procedures. Both HS images were registered using intensity-based and feature-based techniques with different geometric transformations to perform the HS image fusion, obtaining an HS cube with wide spectral range [435-1638 nm]. Four HS datasets were captured to verify the image registration and the fusion process. Moreover, segmentation and classification methods were evaluated to compare the performance results between the use of the VNIR and NIR data, independently, with respect to the fused data. The results reveal that the proposed methodology for fusing VNIR-NIR data improves the classification results up to 21% of accuracy with respect to the use of each data modality independently, depending on the targeted classification problem.

Variability of Clinical and Angiographic Results Based on the Treatment Preference (Endovascular or Surgical) of Centers Participating in the Subarachnoid Hemorrhage Database of the Working Group of the Spanish Society of Neurosurgery.

OBJECTIVES: Since the introduction of endovascular treatment for cerebral aneurysms, hospitals in which subarachnoid hemorrhage is treated show different availability and/or preferences towards both treatment modalities. The main aim is to evaluate the clinical and angiographic results according to the hospital's treatment preferences applied. METHODS: This study was conducted based on use of the subarachnoid hemorrhage database of the Vascular Pathology Group of the Spanish Neurosurgery Society. Centers were classified into 3 subtypes according to an index in the relationship between endovascular and surgical treatment as: endovascular preference, high endovascular preference, and elevated surgical preference. The clinical results and angiographic results were evaluated among the 3 treatment strategies. RESULTS: From November 2004 to December 2017, 4282 subarachnoid hemorrhage patients were selected for the study: 630 (14.7%) patients from centers with surgical preference, 2766 (64.6%) from centers with endovascular preference, and 886 (20.7%) from centers with high endovascular preference. The surgical preference group obtained the best angiographic results associated with a greater complete exclusion (odds ratio: 1.359; 95% confidence interval: 1.025-1.801; P = 0.033). The surgical preference subgroup obtained the best outcome at discharge (65.45%), followed by the high endovascular preference group (61.5%) and the endovascular preference group (57.8%) (odds ratio: 1.359; 95% confidence interval: 1.025-1.801; P = 0.033). CONCLUSIONS: In Spain, there is significant variability in aneurysm exclusion treatment in aneurysmal subarachnoid hemorrhage. Surgical centers offer better results for both surgical and endovascular patients. A multidisciplinary approach and the maintenance of an elevated quality of surgical competence could be responsible for these results.

Most Relevant Spectral Bands Identification for Brain Cancer Detection Using Hyperspectral Imaging.

Hyperspectral imaging (HSI) is a non-ionizing and non-contact imaging technique capable of obtaining more information than conventional RGB (red green blue) imaging. In the medical field, HSI has commonly been investigated due to its great potential for diagnostic and surgical guidance purposes. However, the large amount of information provided by HSI normally contains redundant or non-relevant information, and it is extremely important to identify the most relevant wavelengths for a certain application in order to improve the accuracy of the predictions and reduce the execution time of the classification algorithm. Additionally, some wavelengths can contain noise and removing such bands can improve the classification stage. The work presented in this paper aims to identify such relevant spectral ranges in the visual-and-near-infrared (VNIR) region for an accurate detection of brain cancer using in vivo hyperspectral images. A methodology based on optimization algorithms has been proposed for this task, identifying the relevant wavelengths to achieve the best accuracy in the classification results obtained by a supervised classifier (support vector machines), and employing the lowest possible number of spectral bands. The results demonstrate that the proposed methodology based on the genetic algorithm optimization slightly improves the accuracy of the tumor identification in ~5%, using only 48 bands, with respect to the reference results obtained with 128 bands, offering the possibility of developing customized acquisition sensors that could provide real-time HS imaging. The most relevant spectral ranges found comprise between 440.5-465.96 nm, 498.71-509.62 nm, 556.91-575.1 nm, 593.29-615.12 nm, 636.94-666.05 nm, 698.79-731.53 nm and 884.32-902.51 nm.

Surgical Aid Visualization System for Glioblastoma Tumor Identification based on Deep Learning and In-Vivo Hyperspectral Images of Human Patients.

Brain cancer surgery has the goal of performing an accurate resection of the tumor and preserving as much as possible the quality of life of the patient. There is a clinical need to develop non-invasive techniques that can provide reliable assistance for tumor resection in real-time during surgical procedures. Hyperspectral imaging (HSI) arises as a new, noninvasive and non-ionizing technique that can assist neurosurgeons during this difficult task. In this paper, we explore the use of deep learning (DL) techniques for processing hyperspectral (HS) images of in-vivo human brain tissue. We developed a surgical aid visualization system capable of offering guidance to the operating surgeon to achieve a successful and accurate tumor resection. The employed HS database is composed of 26 in-vivo hypercubes from 16 different human patients, among which 258,810 labelled pixels were used for evaluation. The proposed DL methods achieve an overall accuracy of 95% and 85% for binary and multiclass classifications, respectively. The proposed visualization system is able to generate a classification map that is formed by the combination of the DL map and an unsupervised clustering via a majority voting algorithm. This map can be adjusted by the operating surgeon to find the suitable configuration for the current situation during the surgical procedure.

Deep Learning-Based Framework for In Vivo Identification of Glioblastoma Tumor using Hyperspectral Images of Human Brain.

The main goal of brain cancer surgery is to perform an accurate resection of the tumor, preserving as much normal brain tissue as possible for the patient. The development of a non-contact and label-free method to provide reliable support for tumor resection in real-time during neurosurgical procedures is a current clinical need. Hyperspectral imaging is a non-contact, non-ionizing, and label-free imaging modality that can assist surgeons during this challenging task without using any contrast agent. In this work, we present a deep learning-based framework for processing hyperspectral images of in vivo human brain tissue. The proposed framework was evaluated by our human image database, which includes 26 in vivo hyperspectral cubes from 16 different patients, among which 258,810 pixels were labeled. The proposed framework is able to generate a thematic map where the parenchymal area of the brain is delineated and the location of the tumor is identified, providing guidance to the operating surgeon for a successful and precise tumor resection. The deep learning pipeline achieves an overall accuracy of 80% for multiclass classification, improving the results obtained with traditional support vector machine (SVM)-based approaches. In addition, an aid visualization system is presented, where the final thematic map can be adjusted by the operating surgeon to find the optimal classification threshold for the current situation during the surgical procedure.

An Intraoperative Visualization System Using Hyperspectral Imaging to Aid in Brain Tumor Delineation.

Hyperspectral imaging (HSI) allows for the acquisition of large numbers of spectral bands throughout the electromagnetic spectrum (within and beyond the visual range) with respect to the surface of scenes captured by sensors. Using this information and a set of complex classification algorithms, it is possible to determine which material or substance is located in each pixel. The work presented in this paper aims to exploit the characteristics of HSI to develop a demonstrator capable of delineating tumor tissue from brain tissue during neurosurgical operations. Improved delineation of tumor boundaries is expected to improve the results of surgery. The developed demonstrator is composed of two hyperspectral cameras covering a spectral range of 400-1700 nm. Furthermore, a hardware accelerator connected to a control unit is used to speed up the hyperspectral brain cancer detection algorithm to achieve processing during the time of surgery. A labeled dataset comprised of more than 300,000 spectral signatures is used as the training dataset for the supervised stage of the classification algorithm. In this preliminary study, thematic maps obtained from a validation database of seven hyperspectral images of in vivo brain tissue captured and processed during neurosurgical operations demonstrate that the system is able to discriminate between normal and tumor tissue in the brain. The results can be provided during the surgical procedure (~1 min), making it a practical system for neurosurgeons to use in the near future to improve excision and potentially improve patient outcomes.

Prognostic value of changes in brain tissue oxygen pressure before and after decompressive craniectomy following severe traumatic brain injury.

OBJECTIVE In severe traumatic brain injury (TBI), the effects of decompressive craniectomy (DC) on brain tissue oxygen pressure (PbtO2) and outcome are unclear. The authors aimed to investigate whether changes in PbtO2 after DC could be used as an independent prognostic factor. METHODS The authors conducted a retrospective, observational study at 2 university hospital ICUs. The study included 42 patients who were admitted with isolated moderate or severe TBI and underwent intracranial pressure (ICP) and PbtO2 monitoring before and after DC. The indication for DC was an ICP higher than 25 mm Hg refractory to first-tier medical treatment. Patients who underwent primary DC for mass lesion evacuation were excluded. However, patients were included who had undergone previous surgery as long as it was not a craniectomy. ICP/PbtO2 monitoring probes were located in an apparently normal area of the most damaged hemisphere based on cranial CT scanning findings. PbtO2 values were routinely recorded hourly before and after DC, but for comparisons the authors used the first PbtO2 value on ICU admission and the number of hours with PbtO2 < 15 mm Hg before DC, as well as the mean PbtO2 every 6 hours during 24 hours pre- and post-DC. The end point of the study was the 6-month Glasgow Outcome Scale; a score of 4 or 5 was considered a favorable outcome, whereas a score of 1-3 was considered an unfavorable outcome. RESULTS Of the 42 patients included, 26 underwent unilateral DC and 16 bilateral DC. The median Glasgow Coma Scale score at the scene of the accident or at the initial hospital before the patient was transferred to one of the 2 ICUs was 7 (interquartile range [IQR] 4-14). The median time from admission to DC was 49 hours (IQR 7-301 hours). Before DC, the median ICP and PbtO2 at 6 hours were 35 mm Hg (IQR 28-51 mm Hg) and 11.4 mm Hg (IQR 3-26 mm Hg), respectively. In patients with favorable outcome, PbtO2 at ICU admission was higher and the percentage of time that pre-DC PbtO2 was < 15 mm Hg was lower (19 ± 4.5 mm Hg and 18.25% ± 21.9%, respectively; n = 28) than in those with unfavorable outcome (12.8 ± 5.2 mm Hg [p < 0.001] and 59.58% ± 38.8% [p < 0.001], respectively; n = 14). There were no significant differences in outcomes according to the mean PbtO2 values only during the last 12 hours before DC, the hours of refractory intracranial hypertension, the timing of DC from admission, or the presence/absence of previous surgery. In contrast, there were significant differences in PbtO2 values during the 12- to 24-hour period before DC. In most patients, PbtO2 increased during the 24 hours after DC but these changes were more pronounced in patients with favorable outcome than in those with unfavorable outcome (28.6 ± 8.5 mm Hg vs 17.2 ± 5.9 mm Hg, p < 0.0001; respectively). The areas under the curve for the mean PbtO2 values at 12 and 24 hours after DC were 0.878 (95% CI 0.75-1, p < 0.0001) and 0.865 (95% CI 0.73-1, p < 0.0001), respectively. CONCLUSIONS The authors' findings suggest that changes in PbtO2 before and after DC, measured with probes in healthy-appearing areas of the most damaged hemisphere, have independent prognostic value for the 6-month outcome in TBI patients.

Variabilidad en el manejo de la hemorragia subaracnoidea aneurismática en España: análisis de la base de datos multicéntrica del Grupo de Trabajo de Patología Vascular de la Sociedad Española de Neurocirugía / Variability in the management of aneurysmal subarachnoid haemorrhage in Spain: Analysis of the prospective multicenter database from the Working Group on Neurovascular Diseases of the Spanish Society of Neurosurgery

Introducción: En la hemorragia subaracnoidea aneurismática, la exclusión endovascular o quirúrgica del aneurisma responsable del sangrado de la circulación cerebral es mandatoria para prevenir el resangrado. En España no existen datos sobre la frecuencia de utilización de ambas técnicas, el momento en el que se realiza el tratamiento, la existencia de variabilidad entre los diferentes centros que tratan estos pacientes o los factores que condicionan la elección de una u otra modalidad terapéutica. Objetivos:1) Describir la variabilidad en el uso del tratamiento endovascular o la cirugía en el tratamiento de estos pacientes entre los centros participantes. 2) Establecer qué factores se relacionan con la elección del tipo de tratamiento y el resultado final. Material y métodos: De la totalidad de los pacientes en la base de datos, se seleccionaron los 2150 casos con HSA aneurismática confirmada provenientes de los 10 centros que incluyeron enfermos de forma regular durante el periodo 2004-2012 con un índice de cumplimentación de las variables de estudio superior al 95%. Se realizó un análisis descriptivo con respecto al tipo de tratamiento utilizado y un estudio multivariable de regresión logística para establecer los factores relacionados con la elección del tipo de tratamiento y con la evolución final. Resultados: La ratio de tratamiento endovascular/tratamiento quirúrgico fue de 1,32. Se observó una elevada variabilidad con respecto al uso del tratamiento endovascular entre centros (32-80%). Un 17% de los aneurismas no recibieron tratamiento siendo este porcentaje mayor en aquellos centros con menor uso del tratamiento endovascular. Los centros con menor volumen de tratamiento trataban los aneurismas más tardíamente. La edad y el mal grado al ingreso fueron factores que favorecieron el uso del tratamiento endovascular mientras que la localización a nivel de la cerebral media y las características morfológicas poco favorables de tratamiento quirúrgico. La elección del tipo de tratamiento o el volumen de pacientes tratados no influyeron en la evolución final. Conclusiones: Hay una elevada variabilidad intercentros en la elección del tipo de tratamiento de estos pacientes en España. El tratamiento endovascular permite que un mayor número de pacientes sean tratados. La adherencia a las guías de tratamiento es moderado

Introduction: In aneurysmal subarachnoid haemorrhage, endovascular or surgical exclusion of the aneurysm responsible for the bleeding is mandatory to prevent re-bleeding. In Spain there is no data regarding the frequency of usage of the two techniques, the moment treatment is performed, the existence of variability among the different centres treating these patients or the factors that determine the election of the therapeutic modality. Objectives: 1) To describe the variability in the use of endovascular treatment or surgery in the treatment of these patients among the participating centres. 2) To establish which factors are related to the election of treatment and outcome. Materials and methods: Of all the patients included in the database, we selected 2,150 cases suffering confirmed aneurysmal subarachnoid haemorrhage from 10 centres that included patients regularly during the period between 2004 and 2012 with a data completeness index over 95%. A descriptive analysis on mode of aneurysm treatment was performed. A multivariate analysis of the factors related to treatment modality of the aneurysm and outcome was performed using logistic regression. Results: The ratio endovascular/surgical treatment was 1.32. There was high variability among centres regarding the frequency of endovascular treatment (32-80%). No treatment was given to 17% of the aneurysms, with this percentage being higher in the centres with lower rates of endovascular treatment. Lower volume centres treated aneurysms later. Age and poor clinical grade were factors related to the election of endovascular treatment, while middle cerebral artery location and unfavourable morphological criteria were factors of surgical treatment. The choice of treatment, guideline adherence and centre patient volume were not related to outcome. Conclusions: There is high variability in the election of treatment modality among centres in Spain. Endovascular treatment allows more patients to have their aneurysm treated. Guideline adherence is moderate

[Variability in the management of aneurysmal subarachnoid haemorrhage in Spain: Analysis of the prospective multicenter database from the Working Group on Neurovascular Diseases of the Spanish Society of Neurosurgery]. / Variabilidad en el manejo de la hemorragia subaracnoidea aneurismática en España: análisis de la base de datos multicéntrica del Grupo de Trabajo de Patología Vascular de la Sociedad Española de Neurocirugía.

INTRODUCTION: In aneurysmal subarachnoid haemorrhage, endovascular or surgical exclusion of the aneurysm responsible for the bleeding is mandatory to prevent re-bleeding. In Spain there is no data regarding the frequency of usage of the two techniques, the moment treatment is performed, the existence of variability among the different centres treating these patients or the factors that determine the election of the therapeutic modality. OBJECTIVES: 1) To describe the variability in the use of endovascular treatment or surgery in the treatment of these patients among the participating centres. 2) To establish which factors are related to the election of treatment and outcome. MATERIALS AND METHODS: Of all the patients included in the database, we selected 2,150 cases suffering confirmed aneurysmal subarachnoid haemorrhage from 10 centres that included patients regularly during the period between 2004 and 2012 with a data completeness index over 95%. A descriptive analysis on mode of aneurysm treatment was performed. A multivariate analysis of the factors related to treatment modality of the aneurysm and outcome was performed using logistic regression. RESULTS: The ratio endovascular/surgical treatment was 1.32. There was high variability among centres regarding the frequency of endovascular treatment (32-80%). No treatment was given to 17% of the aneurysms, with this percentage being higher in the centres with lower rates of endovascular treatment. Lower volume centres treated aneurysms later. Age and poor clinical grade were factors related to the election of endovascular treatment, while middle cerebral artery location and unfavourable morphological criteria were factors of surgical treatment. The choice of treatment, guideline adherence and centre patient volume were not related to outcome. CONCLUSIONS: There is high variability in the election of treatment modality among centres in Spain. Endovascular treatment allows more patients to have their aneurysm treated. Guideline adherence is moderate.

Validation of a prognostic score for early mortality in severe head injury cases.

OBJECT: Traumatic brain injury (TBI) represents a large health and economic burden. Because of the inability of previous randomized controlled trials (RCTs) on TBI to demonstrate the expected benefit of reducing unfavorable outcomes, the IMPACT (International Mission on Prognosis and Analysis of Clinical Trials in TBI) and CRASH (Corticosteroid Randomisation After Significant Head Injury) studies provided new methods for performing prognostic studies of TBI. This study aimed to develop and externally validate a prognostic model for early death (within 48 hours). The secondary aim was to identify patients who were more likely to succumb to an early death to limit their inclusion in RCTs and to improve the efficiency of RCTs. METHODS: The derivation cohort was recruited at 1 center, Hospital 12 de Octubre, Madrid (1990-2003, 925 patients). The validation cohort was recruited in 2004-2006 from 7 study centers (374 patients). The eligible patients had suffered closed severe TBIs. The study outcome was early death (within 48 hours post-TBI). The predictors were selected using logistic regression modeling with bootstrapping techniques, and a penalized reduction was used. A risk score was developed based on the regression coefficients of the variables included in the final model. RESULTS: In the validation set, the final model showed a predictive ability of 50% (Nagelkerke R(2)), with an area under the receiver operating characteristic curve of 89% and an acceptable calibration (goodness-of-fit test, p = 0.32). The final model included 7 variables, and it was used to develop a risk score with a range from 0 to 20 points. Age provided 0, 1, 2, or 3 points depending on the age group; motor score provided 0 points, 2 (untestable), or 3 (no response); pupillary reactivity, 0, 2 (1 pupil reacted), or 6 (no pupil reacted); shock, 0 (no) or 2 (yes); subarachnoid hemorrhage, 0 or 1 (severe deposit); cisternal status, 0 or 3 (compressed/absent); and epidural hematoma, 0 (yes) or 2 (no). Based on the risk of early death estimated with the model, 4 risk of early death groups were established: low risk, sum score 0-3 (< 1% predicted mortality); moderate risk, sum score 4-8 (predicted mortality between 1% and 10%); high risk, sum score 9-12 (probability of early death between 10% and 50%); and very high risk, sum score 13-20 (early mortality probability > 50%). This score could be used for selecting patients for clinical studies. For example, if patients with very high risk scores were excluded from our study sample, the patients included (eligibility score < 13) would represent 80% of the original sample and only 23% of the patients who died early. CONCLUSIONS: The combination of Glasgow Coma Scale score, CT scanning results, and secondary insult data into a prognostic score improved the prediction of early death and the classification of TBI patients.

Modification of glucose metabolism in brain tumors by using cervical spinal cord stimulation.

OBJECT: In previous studies the authors have shown potential increases in locoregional blood flow and oxygenation in tumors by using electrical cervical spinal cord stimulation (SCS). In the present report they demonstrate the effect of cervical SCS on brain tumor metabolism, as assessed using [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET). METHODS: Cervical devices were inserted in 11 patients who had high-grade gliomas, six of which had recurred. While the SCS device was deactivated, each patient underwent an initial FDG-PET study to clarify the clinical status. A second FDG-PET study was performed later the same day while the stimulation device was activated to determine the effect of cervical SCS on glucose metabolism. All 11 patients were invaluable for this PET study. Basal glucose metabolism was higher in the tumor than in the peritumoral areas (p = 0.048). There was a significant increase in glucose uptake during cervical SCS in both the tumor (p = 0.035) and the peritumoral (p = 0.001) areas, with measured increases of 43 and 38%, respectively. The estimated potential maximal residual activity of the first FDG dose's contribution to the activity on the second scan was 18.5 +/- 1% or less. CONCLUSIONS: This PET study is the first in which is described the effect of cervical SCS on glucose metabolism in brain tumors and supports previous study data indicating a modification of locoregional blood flow and oxygenation by cervical SCS. These results open up new approaches to modifying the effect of radiochemotherapy in the treatment of malignant brain tumors.

Blood flow increase by cervical spinal cord stimulation in middle cerebral and common carotid arteries.

The effect of spinal cord stimulation (SCS) on cerebral blood flow (CBF) has, in the past, been evaluated by semiquantitative techniques, but has not been used to treat CBF diseases. The aim of this study was to assess the effect of cervical SCS on regional blood flow by both semiquantitative and quantitative methods. Thirty-five patients with cervical SCS-implanted devices were enrolled. The following parameters were measured before and after cervical SCS: systolic and diastolic velocity (cm/s) in the middle cerebral artery (MCA) by transcranial Doppler (TCD) and volume blood flow quantification (ml/min) in the common carotid artery (CCA) by color Doppler. During cervical SCS there was a significant and bilateral increase in systolic (21%) and diastolic (26%) velocity in the MCA and in CCA blood flow (50%). We conclude that cervical SCS increases blood flow in the middle cerebral artery and common carotid artery. The consistent increase supports the potential usefulness of cervical SCS as an adjuvant treatment for cerebral blood flow diseases.

Effect of ozone therapy on muscle oxygenation.

BACKGROUND AND OBJECTIVE: Ozone therapy is being used to treat ischemic disorders. However, the underlying mechanisms for the success are unknown and the therapy has not been accepted fully within conventional medicine. This study sought to assess the effect of ozone therapy on resting muscle oxygenation. PATIENTS AND DESIGN: Twenty-three (23) patients and 3 volunteers were recruited for this prospective study. Systemic ozone therapy was administered by autohemotransfusion on three alternate days over 1 week. Tissue oxygenation (mmHg) was directly measured in the tibialis anterior muscle using polarographic needle electrodes before and after the first and the third ozone therapy session. RESULTS: Globally, the differences in oxygenation were not statistically significant but there was a significant decrease in the percentage of low-oxygenated values (pO(2) < 5 mmHg) following ozone sessions (p < 0.02). The change in muscle oxygenation following ozone therapy was inversely correlated with age (r = -0.398; p = 0.044) and with the initial (baseline pretherapy) muscle oxygenation values (r = -0.644; p < 0.001), indicating that the more poorly oxygenated muscles benefited most from the therapy. A significant (p = 0.031) higher oxygenation in these tissues was observed 48 hours after the second session. CONCLUSIONS: Ozone therapy can modify oxygenation in resting muscles, particularly of those that are most hypoxic. Our results suggest that ozone therapy could be used effectively as a complementary treatment of hypoxic and ischemic syndromes and that the therapy warrants further investigation for possible application in other clinical conditions.

Increased locoregional blood flow in brain tumors after cervical spinal cord stimulation.

OBJECT: Patients with high-grade gliomas have poor prognoses following standard treatment. Generally, malignant brain tumors have a decreased blood flow that results in increased resistance to radiation and reduced delivery of chemotherapeutic agents and oxygen. The aim of the present study was to assess the effect of spinal cord stimulation (SCS) on locoregional blood flow in high-grade tumors in the brain. METHODS: Fifteen patients (11 with Grade III and four with Grade IV brain tumors) had SCS devices inserted prior to scheduled radiotherapy. Both before and after SCS, the patients underwent the following procedures: 1) single-photon emission computerized tomography (SPECT) scanning; 2) middle cerebral artery (MCA) blood flow velocity measurements (centimeters/second) with the aid of transcranial Doppler (TCD) ultrasonography; and 3) common carotid artery (CCA) blood flow volume quantification (milliliters/minute) based on time-domain processing by using color Doppler ultrasonography. The indices demonstrated on SPECT scanning before SCS were significantly lower (p < 0.001) in tumor sites compared with those in peritumoral sites (32%) and healthy contralateral areas (41%). Poststimulation results revealed the following: 1) a mean increase of 15% in tumor blood flow in 75% of patients (p = 0.033), as demonstrated on SPECT scanning: 2) a mean increase of greater than 18% in systolic and diastolic blood flow velocities in both tumorous and healthy MCAs in all but one patient (p < 0.002), as exhibited on TCD ultrasonography; and 3) a mean increase of greater than 60% in blood flow volume in tumorous and healthy CCAs in all patients (p < 0.013), as revealed on color Doppler ultrasonography studies. CONCLUSIONS: Preliminary data show that SCS can modify locoregional blood flow in high-grade malignant tumors in the brain, thus indicating that SCS could be used to improve blood flow, oxygenation, and drug delivery to such tumors and could be a useful adjuvant in chemoradiotherapy.

Influence of haemoglobin concentration and peripheral muscle pO2 on tumour oxygenation in advanced head and neck tumours.

Haemoglobin concentrations and tumour-pO(2) were evaluated pre-therapy in 30 patients with head and neck cancers. Anterior tibialis muscle-pO(2) was additionally measured in 16 of these patients. Tumour-pO(2) was lower in the most anaemic patients (P=0.032) and correlated with muscle-pO(2) (r=0.809, P<0.001). These results suggest that haemoglobin concentration influences tumour-oxygenation.

Increase of brain tumor oxygenation during cervical spinal cord stimulation. Report of three cases.

Malignant brain tumors have been shown to decrease O2 and blood flow resulting in hypoxia and low perfusion that in turn reduce radiation sensitivity and access by chemotherapeutic agents. Spinal cord stimulation (SCS) is a procedure that has been used quite successfully in the treatment of pain and ischemic syndromes. In the present study the authors applied the method and, with polarographic probes inserted in the tumor sites, measured the changes in tissue oxygenation and hypoxia in two separate tumor areas in three patients with high-grade astrocytomas. The results of the SCS indicated that overall tumor oxygenation increased by 90% (from 13.2+/-9.4 mm Hg to 25.1+/-9.6 mm Hg; p = 0.013); the percentage of moderately hypoxic values (< 10 mm Hg) decreased by 55% (from 48.6+/-20.1% to 22+/-13.3%; p = 0.026); and the percentage of considerably hypoxic values (< 5 mm Hg) decreased by 45% (from 28+/-20.3% to 15.5+/-15%; p = 0.018). In this report the authors describe a potential novel application of SCS, and the preliminary results suggest that tumor tissue oxygenation and hypoxia are significantly improved as a result. If these findings are confirmed, the method may be applicable as an adjuvant to radiotherapy and chemotherapy regimens.