Risk of early failure of VP shunts implanted for hydrocephalus after craniotomies for brain tumors in adults.

Risks and survival times of ventriculoperitoneal (VP) shunts implanted due to hydrocephalus after craniotomies for brain tumors are largely unknown. The purpose of this study was to determine the overall timing of VP shunting and its failure after craniotomy for brain tumors in adults. The authors also wished to explore risk factors for early VP shunt failure (within 90 days). A population-based consecutive patient cohort of all craniotomies for intracranial tumors leading to VP shunt dependency in adults (> 18 years) from 2004 to 2013 was studied. Patients with pre-existing VP shunts prior to craniotomy were excluded. The survival time of VP shunts, i.e., the shunt longevity, was calculated from the day of shunt insertion post-craniotomy for a brain tumor until the day of shunt revision requiring replacement or removal of the shunt system. Out of 4774 craniotomies, 85 patients became VP shunt-dependent (1.8% of craniotomies). Median time from craniotomy to VP shunting was 1.9 months. Patients with hydrocephalus prior to tumor resection (N = 39) had significantly shorter time to shunt insertion than those without (N = 46) (p < 0.001), but there was no significant difference with respect to early shunt failure. Median time from shunt insertion to shunt failure was 20 days (range 1-35). At 90 days, 17 patients (20%) had confirmed shunt failure. Patient age, sex, tumor location, primary/secondary craniotomy, extra-axial/intra-axial tumor, ventricular entry, post-craniotomy bleeding, and infection did not show statistical significance. The risk of early shunt failure (within 90 days) of shunts after craniotomies for brain tumors was 20%. This study can serve as benchmark for future studies.

The effect of tumor removal via craniotomies on preoperative hydrocephalus in adult patients with intracranial tumors.

The efficacy of tumor removal via craniotomies on preoperative hydrocephalus (HC) in adult patients with intracranial tumors is largely unknown. Therefore, we sought to evaluate the effect of tumor resection in patients with preoperative HC and identify the incidence and risk factors for postoperative VP shunt dependency. All craniotomies for intracranial tumors at Oslo University Hospital in patients ≥ 18 years old during a 10-year period (2004-2013) were reviewed. Patients with radiologically confirmed HC requiring surgery and subsequent development of shunt dependency were identified by cross-linking our prospectively collected tumor database to surgical procedure codes for hydrocephalus treatment (AAF). Patients with preexisting ventriculoperitoneal (VP) shunts (N = 41) were excluded. From 4774 craniotomies performed on 4204 patients, a total of 373 patients (7.8%) with HC preoperatively were identified. Median age was 54.4 years (range 18.1-83.9 years). None were lost to follow-up. Of these, 10.5% (39/373) required permanent CSF shunting due to persisting postoperative HC. The risk of becoming VP shunt dependent in patients with preexisting HC was 7.0% (26/373) within 30 days and 8.9% (33/373) within 90 days. Only secondary (repeat) surgery was a significant risk factor for VP shunt dependency. In this large, contemporary, single-institution consecutive series, 10.5% of intracranial tumor patients with preoperative HC became shunt-dependent post-craniotomy, yielding a surgical cure rate for HC of 89.5%. To the best of our knowledge, this is the first and largest study regarding postoperative shunt dependency after craniotomies for intracranial tumors, and can serve as benchmark for future studies.

Dynamic susceptibility contrast and diffusion MR imaging identify oligodendroglioma as defined by the 2016 WHO classification for brain tumors: histogram analysis approach.

PURPOSE: According to the revised World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) of 2016, oligodendrogliomas are now defined primarily by a specific molecular signature (presence of IDH mutation and 1p19q codeletion). The purpose of our study was to assess the value of dynamic susceptibility contrast MR imaging (DSC-MRI) and diffusion-weighted imaging (DWI) to characterize oligodendrogliomas and to distinguish them from astrocytomas. METHODS: Seventy-one adult patients with untreated WHO grade II and grade III diffuse infiltrating gliomas and known 1p/19q codeletion status were retrospectively identified and analyzed using relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) maps based on whole-tumor volume histograms. The Mann-Whitney U test and logistic regression were used to assess the ability of rCBV and ADC to differentiate between oligodendrogliomas and astrocytomas both independently, but also related to the WHO grade. Prediction performance was evaluated in leave-one-out cross-validation (LOOCV). RESULTS: Oligodendrogliomas showed significantly higher microvascularity (higher rCBVMean ≥ 0.80, p = 0.013) and higher vascular heterogeneity (lower rCBVPeak ≤ 0.044, p = 0.015) than astrocytomas. Diffuse gliomas with higher cellular density (lower ADCMean ≤ 1094 × 10-6 mm2/s, p = 0.009) were more likely to be oligodendrogliomas than astrocytomas. Histogram analysis of rCBV and ADC was able to differentiate between diffuse astrocytomas (WHO grade II) and anaplastic astrocytomas (WHO grade III). CONCLUSION: Histogram-derived rCBV and ADC parameter may be used as biomarkers for identification of oligodendrogliomas and may help characterize diffuse gliomas based upon their genetic characteristics.

Analyzing Boron in 9-12% Chromium Steels Using Atom Probe Tomography.

Small additions of boron can remarkably improve the long-term creep resistance of 9-12% Cr steels. The improvement has been attributed to boron segregation to grain boundaries during quenching, and subsequent boron incorporation into certain families of precipitates during tempering. However, the detailed mechanisms are not yet fully understood. Atom probe tomography (APT) is an excellent technique for gaining insights into boron distribution, however, in order to acquire accurate analysis of boron in 9-12% Cr steels using APT, there are several key challenges. In order to better understand and address these challenges, we developed a novel method for site-specific APT specimen preparation, which enables convenient preparation of specimens containing specifically selected grain boundaries positioned approximately perpendicular to the axis of the APT tip. Additionally, when analyzing boron at boundaries and in carbides (as diluted solute) and borides, a widening of the profile of boron distribution compared to other elements was repeatedly observed. This phenomenon is particularly analyzed and discussed in light of the evaporation field of different elements. Finally, the possible effects of detector dead-time on quantitative analysis of boron in metal borides are discussed. A simple method using 10B correction was used to obtain good quantification.

Survival Associations Using Perfusion and Diffusion Magnetic Resonance Imaging in Patients With Histologic and Genetic Defined Diffuse Glioma World Health Organization Grades II and III.

OBJECTIVE: According to the new World Health Organization 2016 classification for tumors of the central nervous system, 1p/19q codeletion defines the genetic hallmark that differentiates oligodendrogliomas from diffuse astrocytomas. The aim of our study was to evaluate whether relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) histogram analysis can stratify survival in adult patients with genetic defined diffuse glioma grades II and III. METHODS: Sixty-seven patients with untreated diffuse gliomas World Health Organization grades II and III and known 1p/19q codeletion status were included retrospectively and analyzed using ADC and rCBV maps based on whole-tumor volume histograms. Overall survival and progression-free survival (PFS) were analyzed by using Kaplan-Meier and Cox survival analyses adjusted for known survival predictors. RESULTS: Significant longer PFS was associated with homogeneous rCBV distribution-higher rCBVpeak (median, 37 vs 26 months; hazard ratio [HR], 3.2; P = 0.02) in patients with astrocytomas, and heterogeneous rCBV distribution-lower rCBVpeak (median, 46 vs 37 months; HR, 5.3; P < 0.001) and higher rCBVmean (median, 44 vs 39 months; HR, 7.9; P = 0.003) in patients with oligodendrogliomas. Apparent diffusion coefficient parameters (ADCpeak, ADCmean) did not stratify PFS and overall survival. CONCLUSIONS: Tumors with heterogeneous perfusion signatures and high average values were associated with longer PFS in patients with oligodendrogliomas. On the contrary, heterogeneous perfusion distribution was associated with poor outcome in patients with diffuse astrocytomas.

Risk factors for new-onset shunt-dependency after craniotomies for intracranial tumors in adult patients.

The risk of developing a de novo shunt-dependent hydrocephalus (HC) after undergoing a craniotomy for brain tumor in adult patients is largely unknown. All craniotomies for intracranial tumors at Oslo University Hospital in adult patients ≥18 years of age during a 10-year period (2004-2013) were included. None were lost to follow-up. Patients who developed a shunt-dependent HC were identified by cross-linking our prospectively collected tumor database to patients with a NCSP surgical procedure code of hydrocephalus (AAF). Patients with pre-existing HC or ventriculoperitoneal (VP) shunts were excluded from the study. A total of 4401 craniotomies were performed. Of these, 46 patients (1.0%) developed de novo postoperative HC requiring a VP shunt after a median of 93 days (mean 115 days, range 6-442). Median age was 62.0 years (mean 58.9 years, range 27.3-80.9) at time of VP shunt surgery. Patients without pre-existing HC had a 0.2% (n = 8/4401) risk of becoming VP shunt dependent within 30 days and 0.5% (n = 22/4401) within 90 days. Age, sex, tumor location, primary/secondary surgery, and radiotherapy were not associated with VP shunt dependency. Choroid plexus tumors and craniopharyngiomas had increased risk of VP shunt dependency. In this large, contemporary, single-institution consecutive series, the risk of postoperative shunt-dependency after craniotomies for brain tumors without pre-existing HC was very low. This is the largest study with regards to de novo postoperative shunt-dependency after craniotomies for patients with intracranial tumors and can serve as a benchmark for future studies.

Imaging spectrum of central nervous system complications of hematopoietic stem cell and solid organ transplantation.

Neurologic complications are common after hematopoietic stem cell transplantation (HSCT) and solid organ transplantation (SOT) and affect 30-60% of transplant recipients. The aim of this article is to provide a practical imaging approach based on the timeline and etiology of CNS abnormalities, and neurologic complications related to transplantation of specific organs. The lesions will be classified based upon the interval from HSCT procedure: pre-engraftment period <30 days, early post-engraftment period 30-100 days, late post-engraftment period >100 days, and the interval from SOT procedure: postoperative phase 1-4 weeks, early posttransplant syndromes 1-6 months, late posttransplant syndromes >6 months. Further differentiation will be based on etiology: infections, drug toxicity, metabolic derangements, cerebrovascular complications, and posttransplantation malignancies. In addition, differentiation will be based on complications specific to the type of transplantation: allogeneic and autologous hematopoietic stem cells (HSC), heart, lung, kidney, pancreas, and liver. Thus, in this article we emphasize the strategic role of neuroradiology in the diagnosis and response to treatment by utilizing a methodical approach in the work up of patients with neurologic complications after transplantation.

Seizure outcomes of temporal lobe epilepsy surgery in patients with normal MRI and without specific histopathology.

BACKGROUND: Seizure outcome following surgery in pharmacoresistant temporal lobe epilepsy patients with normal magnetic resonance imaging and normal or non-specific histopathology is not sufficiently presented in the literature. METHODS: In a retrospective design, we reviewed data of 263 patients who had undergone temporal lobe epilepsy surgery and identified 26 (9.9%) who met the inclusion criteria. Seizure outcomes were determined at 2-year follow-up. Potential predictors of Engel class I (satisfactory outcome) were identified by logistic regression analyses. RESULTS: Engel class I outcome was achieved in 61.5% of patients, 50% being completely seizure free (Engel class IA outcome). The strongest predictors of satisfactory outcome were typical ictal seizure semiology (p = 0.048) and localised ictal discharges on scalp EEG (p = 0.036). CONCLUSION: Surgery might be an effective treatment choice for the majority of these patients, although outcomes are less favourable than in patients with magnetic resonance imaging-defined lesional temporal lobe epilepsy. Typical ictal seizure semiology and localised ictal discharges on scalp EEG were predictors of Engel class I outcome.

A generic support vector machine model for preoperative glioma survival associations.

PURPOSE: To develop a generic support vector machine (SVM) model by using magnetic resonance (MR) imaging-based blood volume distribution data for preoperative glioma survival associations and to prospectively evaluate the diagnostic effectiveness of this model in autonomous patient data. MATERIALS AND METHODS: Institutional and regional medical ethics committees approved the study, and all patients signed a consent form. Two hundred thirty-five preoperative adult patients from two institutions with a subsequent histologically confirmed diagnosis of glioma after surgery were included retrospectively. An SVM learning technique was applied to MR imaging-based whole-tumor relative cerebral blood volume (rCBV) histograms. SVM models with the highest diagnostic accuracy for 6-month and 1-, 2-, and 3-year survival associations were trained on 101 patients from the first institution. With Cox survival analysis, the diagnostic effectiveness of the SVM models was tested on independent data from 134 patients at the second institution. RESULTS: were adjusted for known survival predictors, including patient age, tumor size, neurologic status, and postsurgery treatment, and were compared with survival associations from an expert reader. RESULTS: Compared with total qualitative assessment by an expert reader, the whole-tumor rCBV-based SVM model was the strongest parameter associated with 6-month and 1-, 2-, and 3-year survival in the independent patient data (area under the receiver operating characteristic curve, 0.794-0.851; hazard ratio, 5.4-21.2). DISCUSSION: Machine learning by means of SVM in combination with whole-tumor rCBV histogram analysis can be used to identify early patient survival in aggressive gliomas. The SVM model returned higher diagnostic accuracy values than an expert reader, and the model appears to be insensitive to patient, observer, and institutional variations.

Seizure outcomes in relation to the extent of resection of the perifocal fluorodeoxyglucose and flumazenil PET abnormalities in anteromedial temporal lobectomy.

BACKGROUND: The area of predominant perifocal [(18)F]fluorodeoxyglucose ((18)F-FDG) hypometabolism and reduced [(11)C]flumazenil ((11)C-FMZ) -binding on PET scans is currently considered to contain the epileptogenic zone and corresponds anatomically to the area localizing epileptogenicity in patients with temporal lobe epilepsy (TLE). The question is whether the volume of the perifocal pre-operative PET abnormalities, the extent of their resection, and the volume of the non-resected abnormalities affects the post-operative seizure outcome. METHODS: The sample group consisted of 32 patients with mesial temporal sclerosis who underwent anteromedial temporal lobe resection for refractory TLE. All patients had pathologic perifocal findings on both of the PET modalities as well as on the whole-brain MRI. The volumetric data of the PET and MRI abnormalities within the resected temporal lobe were estimated by automated quantitative voxel-based analysis. The obtained volumetric data were investigated in relation to the outcome subgroups of patients (Engel classification) determined at the 2-year post-operative follow-up. RESULTS: The mean volume of the pre-operative perifocal (18)F-FDG- and (11)C-FMZ PET abnormalities in the volumes of interest (VOI) of the epileptogenic temporal lobe, the mean resected volume of these PET abnormalities, the mean volume of the non-resected PET abnormalities, and the mean MRI-derived resected volume were not significantly related to the outcome subgroups and had a low prediction for individual freedom from seizures. CONCLUSIONS: The extent of pre-surgical perifocal PET abnormalities, the extent of their resection, and the extent of non-resected abnormalities were not useful predictors of individual freedom from seizures in patients with TLE.

Machine learning in preoperative glioma MRI: survival associations by perfusion-based support vector machine outperforms traditional MRI.

PURPOSE: To retrospectively evaluate the performance of an automatic support vector machine (SVM) routine in combination with perfusion-based dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) for preoperative survival associations in patients with gliomas and compare our results to traditional MRI. MATERIALS AND METHODS: The study was approved by the Ethics Committee and informed consent was signed. Structural, diffusion- and perfusion-weighted MRI was performed at 1.5-T preoperatively in 94 adult patients (49 males, 45 females, 23-82 years; mean 51 years) later diagnosed with a primary glioma. Patients were randomly assigned in training and test datasets and the resulting DSC-based survival associations by SVM were compared to traditional MRI features including contrast-agent enhancement, perfusion- and diffusion-weighted imaging, tumor size, and location. The results were adjusted for age, neurological status, and postoperative factors associated with survival, including surgery and adjuvant therapy. RESULTS: For 1- (26/33 alive, 11/14 deceased), 2- (15/21, 21/26), 3- (12/16, 27/31) and 4- (12/15, 28/32) year survival associations in the test dataset (47 patients), the SVM routine was the only biomarker to consistently associate with survival (Cox; P < 0.001). CONCLUSION: The automatic machine learning routine presented in our study may provide the operator with a reliable instrument for assessing survival in patients with glioma.

Limited utility of current MRI criteria for distinguishing multiple sclerosis from common mimickers: primary and secondary CNS vasculitis, lupus and Sjogren's syndrome.

BACKGROUND: Magnetic resonance imaging (MRI) criteria play an important role in making an earlier diagnosis of multiple sclerosis (MS) in patients presenting with clinically isolated syndrome. OBJECTIVE: The objective of this paper is to determine whether MRI criteria may be used to distinguish MS from primary and secondary central nervous system (CNS) vasculitis, lupus, and Sjogren's syndrome. METHODS: MRI criteria were applied retrospectively to images for patients with clinically definite MS (CDMS), primary CNS vasculitis, secondary CNS vasculitis, and autoimmune disorders including systemic lupus erythematosus (SLE) and Sjogren's syndrome. Classical statistics and Bayesian analyses were performed. RESULTS: Overall modified Barkhof's MRI criteria were statistically significant in distinguishing CDMS (60%) from SLE/Sjogren's syndrome (17%, p = 0.0173) but not in distinguishing CDMS from primary CNS vasculitis (50%, p = 0.7376) or secondary CNS vasculitis (58%, p = 1.0000). Four of the five other MRI criteria tested were demonstrated to be superior to modified Barkhof's criteria in predicting MS: nine or more T2 lesions (a component of Barkhof's criteria), one or more ovoid periventricular T2 lesions, one or more perpendicular periventricular T2 lesions, and one or more T2 lesions larger than 6 mm. CONCLUSIONS: MRI criteria, including the modified Barkhof's criteria, were unsuccessful in distinguishing MS from primary CNS vasculitis or secondary CNS vasculitis and mildly successful in distinguishing MS from SLE/Sjogren's syndrome.

High temperature corrosion and oxide scale formation of nickel in molten NaOH at various basicity levels.

The corrosion behavior of alloy Ni 201 in molten sodium hydroxide (NaOH) at 600 °C was investigated at varying basicity levels of the molten NaOH. The ability for Ni 201 to form passivating oxides was investigated after immersion tests varying from 70 to 340 h under atmospheres of argon and argon with different partial pressure of water. Morphology and thicknesses of the corrosion products were characterized by Scanning Electron Microscopy (SEM) and crystallography of the corrosion products by X-ray Diffraction (XRD). Dynamic polarizations were made to investigate the effects of basicity and electrochemical potential. The results showed that Ni 201 corroded at a reduced rate in molten acidic NaOH compared to neutral NaOH due to the formation of NiO. The oxide scales formed on Ni 201 in acidic NaOH were shown to grow non-parabolically and did not result in full corrosion protection as the oxide scales showed crack development over time.

Thermophysical Properties of FUNaK (NaF-KF-UF4) Eutectics.

General interest in the deployment of molten salt reactors (MSRs) is growing, while the available data on uranium-containing fuel salt candidates remains scarce. Thermophysical data are one of the key parameters for reactor design and understanding reactor operability. Hence, filling in the gap of the missing data is crucial to allow for the advancement of MSRs. This study provides novel data for two eutectic compositions within the NaF-KF-UF4 ternary system which serve as potential fuel candidates for MSRs. Experimental measurements include their melting point, density, fusion enthalpy, and vapor pressure. Additionally, their boiling point was extrapolated from the vapor pressure data, which were, at the same time, used to determine the enthalpy of vaporization. The obtained thermodynamic values were compared with available data from the literature but also with results from thermochemical equilibrium calculations using the JRCMSD database, finding a good correlation, which thus contributed to database validation. Preliminary thoughts on fluoride salt reactor operability based on the obtained results are discussed in this study.

Volume and densities of chronic subdural haematoma obtained from CT imaging as predictors of postoperative recurrence: a prospective study of 107 operated patients.

BACKGROUND: Chronic subdural haematoma (CSDH) is a common entity in neurosurgery with a considerable postoperative recurrence rate. Computerised tomography (CT) scanning remains the most important diagnostic test for this disorder. The aim of this study was to characterise the relationship between the recurrence of CSDH after treatment with burr-hole irrigation and closed-system drainage technique and CT scan features of these lesions to assess whether CT findings can be used to predict recurrence. METHODS: We investigated preoperative and postoperative CT scan features and recurrence rate of 107 consecutive adult surgical cases of CSDH and assessed any relationship with univariate and multivariate regression analyses. RESULTS: Seventeen patients (15.9 %) experienced recurrence of CSDH. The preoperative haematoma volume, the isodense, hyperdense, laminar and separated CT densities and the residual total haematoma cavity volume on the 1st postoperative day after removal of the drainage were identified as radiological predictors of recurrence. If the preoperative haematoma volume was under 115 ml and the residual total haematoma cavity volume postoperatively was under 80 ml, the probability of no recurrence was very high (94.4 % and 97.4 % respectively). CONCLUSIONS: These findings from CT imaging may help to identify patients at risk for postoperative recurrence.

The pulmonary artery in patients with Marfan syndrome: a cross-sectional study.

PURPOSE: The objectives of this study were to establish the prevalence of pulmonary artery dilatation in Marfan syndrome using modern radiological methods and to correlate the diameter of the vessel with aortic disease. METHODS: Magnetic resonance or computed tomography imaging of the pulmonary artery and aorta was performed in 87 patients with proven Marfan syndrome. Diameters of the root and trunk of the pulmonary artery and of the aortic root were measured perpendicular to the long axes of the vessels. Pulmonary artery diameters were measured on axial images, and aortic diameters were assessed on oblique sagittal images. RESULTS: As compared with normal values in the literature, 47 of the 87 patients (54%) had widening of the trunk of the pulmonary artery (≥30 mm). Of these 47, 15% had no sign of disease of the ascending aorta. The mean (SD) ratio between the diameters of the root and trunk of the pulmonary artery was 1.18 (0.155). Multivariate analysis showed that surgery of the ascending aorta and high body surface area were associated with dilatation of the trunk of the pulmonary artery. CONCLUSIONS: Pulmonary artery dilatation is present in a high proportion of patients with Marfan syndrome as assessed using cutoff values based on measurements in the normal population. Severe disease of the ascending aorta correlates significantly with pulmonary artery trunk dilatation in patients with Marfan syndrome.

Assessment of pituitary adenoma volumetric change using longitudinal MR image registration.

INTRODUCTION: Change detection is a crucial factor in monitoring of slowly evolving pathologies. The objective of the study was to test a semi-automatic method applied on longitudinal MRI monitoring of volume change in pituitary macroadenomas. METHODS: The proposed method is based on a visual comparison of geometrically corrected, co-registered, intensity-normalized contrast-enhanced (CE) 3D GRE T1-weighted images. Qualitative volume changes based on this applied method were compared with experts' readings of conventional pre- and post-CE 2D T1-weighted images. Magnetic resonance (MR) imaging was performed two to four times in 13 patients with a total combination of 29 time points. RESULTS: Compared to conventional 2D MR readings, a diagnosis of tumor growth (yes/no) was changed in 5 of 13 patients (38%) at 9 of the 29 combinations of time points (31%) using the 3D-based semi-automatic method. With manual tumor tracings as reference, McNemar's test showed a significant difference between the two methods. CONCLUSION: Visual comparison of geometrically corrected, intensity-normalized, and affine-aligned longitudinal 3D images may enable more accurate assessment of qualitative volumetric change in pituitary adenomas than conventional reading of 2D images.

CT of the hips in the investigation of protrusio acetabuli in Marfan syndrome. A case control study.

OBJECTIVES: To establish the prevalence of protrusio acetabuli (PA) in adults fulfilling the Ghent criteria for Marfan syndrome (MFS), and in a normal adult population. METHODS: 105 adults with probable MFS and 107 controls were included. CT of the hips was obtained. A qualitative assessment of PA was performed. A new method for estimating the degree of PA was introduced with measurement of the parameter CWD (circle-wall distance). Results were compared to an alternative method based on MRI [1]. RESULTS: 87 of the study group fulfilled the Ghent criteria of MFS (Ghent positives), and 18 did not (Ghent negatives). PA was diagnosed qualitatively in 74.7% of Ghent positive persons, in 27.8% of Ghent negative persons, and in 3.7% of the controls. CWD was significantly different between the three groups (p < 0.001). A slight but significant gender difference was found in Ghent positive persons only. The alternative method did not differentiate between the groups with respect to PA, but showed a significant difference between genders. CONCLUSIONS: PA was found significantly more often in MFS persons than in controls. Our method was found to be robust and highly reproducible, giving a direct measurement of pelvic protrusion irrespective of pelvic shape.

Multiparametric analysis of magnetic resonance images for glioma grading and patient survival time prediction.

BACKGROUND: A systematic comparison of magnetic resonance imaging (MRI) options for glioma diagnosis is lacking. PURPOSE: To investigate multiple MR-derived image features with respect to diagnostic accuracy in tumor grading and survival prediction in glioma patients. MATERIAL AND METHODS: T1 pre- and post-contrast, T2 and dynamic susceptibility contrast scans of 74 glioma patients with histologically confirmed grade were acquired. For each patient, a set of statistical features was obtained from the parametric maps derived from the original images, in a region-of-interest encompassing the tumor volume. A forward stepwise selection procedure was used to find the best combinations of features for grade prediction with a cross-validated logistic model and survival time prediction with a cox proportional-hazards regression. RESULTS: Presence/absence of enhancement paired with kurtosis of the FM (first moment of the first-pass curve) was the feature combination that best predicted tumor grade (grade II vs. grade III-IV; median AUC = 0.96), with the main contribution being due to the first of the features. A lower predictive value (median AUC = 0.82) was obtained when grade IV tumors were excluded. Presence/absence of enhancement alone was the best predictor for survival time, and the regression was significant (P < 0.0001). CONCLUSION: Presence/absence of enhancement, reflecting transendothelial leakage, was the feature with highest predictive value for grade and survival time in glioma patients.

Automatic vessel removal in gliomas from dynamic susceptibility contrast imaging.

The presence of macroscopic vessels within the tumor region is a potential confounding factor in MR-based dynamic susceptibility contrast (DSC)-enhanced glioma grading. In order to distinguish between such vessels and the elevated cerebral blood volume (CBV) of brain tumors, we propose a vessel segmentation technique based on clustering of multiple parameters derived from the dynamic contrast-enhanced first-pass curve. A total of 77 adult patients with histologically-confirmed gliomas were imaged at 1.5T and glioma regions-of-interest (ROIs) were derived from the conventional MR images by a neuroradiologist. The diagnostic accuracy of applying vessel exclusion by segmentation of glioma ROIs with vessels included was assessed using a histogram analysis method and compared to glioma ROIs with vessels included. For all measures of diagnostic efficacy investigated, the highest values were observed when the glioma diagnosis was based on vessel segmentation in combination with an initial mean transit time (MTT) mask. Our results suggest that vessel segmentation based on DSC parameters may improve the diagnostic efficacy of glioma grading. The proposed vessel segmentation is attractive because it provides a mask that covers all pixels affected by the intravascular susceptibility effect.