Low field intraoperative MRI-guided surgery of gliomas: A single center experience

Introduction

The aim of this article is to report on our experience in using a low field intraoperative MRI (iMRI) system in glioma surgery and to summarize the hitherto use and benefits of iMRI in glioma surgery.

Patients and methods

Between July 2004 and May 2009, a total of 103 patients harboring gliomas underwent tumor resection with the use of a mobile low field iMRI in our institution. Surgeries were performed as standard micro-neurosurgical procedures using regular instrumentarium. All patients underwent early postoperative high field MRI to determine the extent of resection. Adjuvant treatment was conducted according to histopathological grading and standard of care.

Results

All tumors could be reliably visualized on intraoperative imaging. Intraoperative imaging revealed residual tumor tissue in 51 patients (49.5%), leading to further tumor resection in 31 patients (30.1%). Extended resection did not translate into a higher rate of neurological deficits. When analyzing survival of patients with glioblastoma, patients undergoing complete tumor resection did significantly better than patients with residual tumor (50% survival rate at 57.8 weeks vs. 33.8 weeks, log rank test p = 0.003), while younger age did not influence survival (p = 0.12).

Conclusion

Low field iMRI is a helpful tool in modern neurosurgery and facilitates brain tumor resection to a maximum safe extent. Its use translates into a better prognosis for these patients with devastating tumors. Future studies covering the use of iMRI will need to be conducted in a prospective, randomized fashion to prove the true benefit of iMRI in glioma surgery.     

Correlation of glioma proliferation assessed by flow cytometry with Tc-Tetrofosmin SPECT uptake

Objectives

Brain single-photon emission computed tomography (SPECT) has been proposed as a potentially useful modality for the metabolic assessment of various brain tumors.

Material and methods

In a 10-patient prospective pilot study we evaluated whether ^99mTc-Tetrofosmin (^99mTc-TF) uptake correlates with glioma proliferative activity assessed by flow cytometric analysis. ^99mTc-TF brain SPECT was performed shortly before surgical tumor excision.

Results

Eight patients were diagnosed with glioblastoma multiform and 2 with anaplastic astrocytoma. All tumors were aneuploid. We found a significant positive linear correlation between ^99mTc-TF uptake and percentage of tumor cells on the S-phase of the cell cycle (r = 0.92, P = 0.001).

Conclusion

Initial evidence suggests that ^99mTc-TF could provide a non-invasive indicator of glioma proliferative activity.     

Correlación entre las lesiones desmielinizantes y el deterioro de las funciones ejecutivas en una muestra de pacientes mexicanos con esclerosis múltiple

Background

Multiple Sclerosis (MS) is characterised by several neurological symptoms including cognitive impairment, which has recently been the subject of considerable study. At present, evidence pointing to a correlation between lesion characteristics and specific cognitive impairment is not conclusive.

Objective

To investigate the presence of a correlation between the characteristics of demyelinating lesions and performance of basic executive functions in a sample of MS patients.

Patients and methods

We included 21 adult patients with scores of 0 to 5 on the Kurtzke scale and no exacerbations of the disease in at least 3 months prior to the evaluation date. They completed the Stroop test and the Wisconsin Card Sorting Test (WCST). The location of the lesions was determined using magnetic resonance imaging (MRI) performed by a blinded expert in neuroimaging.

Results

Demyelinating lesions were more frequently located in the frontal and occipital lobes. The Stroop test showed that as cognitive demand increased on each of the sections in the test, reaction time and number of errors increased. On the WCST, 33.33% of patients registered as having moderate cognitive impairment. No correlation could be found between demyelinating lesion characteristics (location, size, and number) and patients’ scores on the tests.

Conclusion

Explanations of the causes of cognitive impairment in MS should examine a variety of biological, psychological, and social factors instead of focusing solely on demyelinating lesions.     

Potential of MR spectroscopy for assessment of glioma grading

Background

Magnetic resonance spectroscopy (MRS) is an imaging diagnostic method based that allows non-invasive measurement of metabolites in tissues. There are a number of metabolites that can be identified by standard brain proton MRS but only a few of them has a clinical significance in diagnosis of gliomas including N-acetylaspartate, choline, creatine, myo-inositol, lactate, and lipids.

Methods

In this review, we describe potential of MRS for grading of gliomas.

Results

Low-grade gliomas are generally characterized by a relatively high concentration of N-acetylaspartate, low level of choline and absence of lactate and lipids. The increase in creatine concentration indicates low-grade gliomas with earlier progression and malignant transformation. Progression in grade of a glioma is reflected in the progressive decrease in the N-acetylaspartate and myo-inositol levels on the one hand and elevation in choline level up to grade III on the other. Malignant transformation of the glial tumors is also accompanied by the presence of lactate and lipids in MR spectra of grade III but mainly grade IV gliomas. It follows that MRS is a helpful method for detection of glioma regions with aggressive growth or upgrading due to favorable correlation of the choline and N-acetylaspartate levels with histopathological proliferation index Ki-67. Thus, magnetic resonance spectroscopy is also a suitable method for the targeting of brain biopsies.

Conclusions

Gliomas of each grade have some specific MRS features that can be used for improvement of the diagnostic value of conventional magnetic resonance imaging in non-invasive assessment of glioma grade.     

Differentiating radiation necrosis from tumor recurrence in high-grade gliomas: Assessing the efficacy of F-FDG PET,C-methionine PET and perfusion MRI

Purpose

The authors analyzed the characteristics of perfusion magnetic resonance imaging (MRI), ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and ¹¹C-methionine (MET) PET to compare the efficacies of these modalities in making the distinction between radiation necrosis and tumor recurrence of high-grade glioma.

Patients and methods

Ten patients were evaluated with dynamic susceptibility contrast perfusion MRI, ¹¹C-MET PET and ¹⁸F-FDG PET to visualize gadolinium-enhanced lesions during the post-radiation follow-up period. In the perfusion MRI, four regions of interest (ROIs) were identified and average values were calculated. A reference ROI of the same size was defined in the contralateral white matter to obtain the relative cerebral blood volume (rCBV). After coregistering the PET images with the MRI, we measured the maximum uptake values of the lesion and of the contralateral cerebral white matter as reference area to calculate the L_max/R_max ratio.

Results

The rCBV was higher in the recurrence group than in the necrosis group (p = 0.010). There was no difference between groups in terms of the L_max/R_max ratio as derived from the ¹⁸F-FDG and ¹¹C-MET PET.

Conclusion

A quantitative rCBV as calculated from a perfusion MRI scan might be superior to the L_max/R_max ratio as derived from ¹⁸F-FDG and ¹¹C-MET PET in order to distinguish a recurrence of high-grade glioma from radiation necrosis.     

Laminar cortical necrosis in mitochondrial disorders

Objectives

Laminar cortical necrosis, defined as focal or diffuse necrosis of one or more cortical lamina, represents an increasingly recognized neuropathological endpoint of vascular, endocrine, immunologic, metabolic, or toxic conditions, of which mitochondrial disorders (MIDs) are the third most frequent after cerebral ischemia and hypoxia.

Aims

To investigate the prevalence of laminar cortical necrosis in MIDs, types of MIDs associated with laminar cortical necrosis, and the morphological characteristics on imaging and autopsy.

Methods

Medline literature review for the terms “laminar cortical necrosis”, “cortical signal change”, “mitochondrial” and all acronyms of syndromatic MIDs.

Results

Among 139 hits for “laminar cortical necrosis”, 10 articles fulfilled the inclusion criteria (7%). Among the ten hits five were case series and the other five single case reports. The syndromic MID most frequently associated with laminar cortical necrosis is the MELAS syndrome, but was also described in a single patient each with Leigh syndrome, mitochondrial depletion syndrome, and mitochondrial spinocerebellar ataxia. The morphological and pathohistological features of laminar cortical necrosis in MIDs were not at variance from those in non-mitochondrial disorders.

Conclusions

In MIDs laminar cortical necrosis represents the histopathological and imaging endpoint of a stroke-like lesion. Though laminar cortical necrosis may have a wide pathophysiological background the histological and imaging characteristics do not vary between the different underlying conditions.     

Noninvasive measurement of human brain temperature adjacent to arteriovenous malformation using 3.0 T magnetic resonance spectroscopy

Object

The brain temperature at rest is determined by the balance between heat produced by cerebral energy turnover, which is identical to cerebral metabolism, and heat that is removed, primarily by cerebral blood flow. The present study investigated whether brain temperature measured by proton magnetic resonance (MR) spectroscopy can detect cerebral hemodynamic impairment in patients with arteriovenous malformations (AVMs) as shown by single photon emission computed tomography (SPECT).

Methods

Brain temperature, cerebral blood flow, and cerebrovascular reactivity were measured using proton MR spectroscopy and SPECT in five healthy volunteers and six patients with AVMs. Regions of interest were selected adjacent to the AVMs and in the corresponding contralateral region.

Results

Brain temperature around AVMs was calculated in all subjects using MR spectroscopy. The mean brain temperature in volunteers was 37.1 ± 0.41 °C. A significant correlation was observed between brain temperature ratio (affected side/contralateral side) and cerebrovascular reactivity ratio (affected side/contralateral side) (r = −0.82, p = 0.0480).

Conclusion

Brain temperature measured by proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with AVMs. Further investigations regarding the relationships between brain temperature and clinical feature in patients with AVMs are needed.     

Kinesin family member 2C (KIF2C/MCAK) is a novel marker for prognosis in human gliomas

Objective

Gliomas are a group of center nervous system tumors of glial origin. Most are characterized by diffuse infiltrative growth in the surrounding brain. Patients almost always ultimately die from their disease. The drastically increased knowledge about the molecular abnormalities, these are linked with tumor grade and patient prognosis. The aim of this study was to examine the role of KIF2C and AURKB as prognostic factors in gliomas.

Materials and methods

A total 40 tumor samples and 6 normal brain tissue samples were collected. Biomarker KIF2C and AURKB were tested by qRT-PCR. Using Western blot validate the results.

Results

We found that KIF2C and AURKB genes were higher expression in glioma samples when were compared with normal brain tissues. KIF2C and AURKB expression were associated with histopathological grades. We found that KIF2C as a potential independent prognostic marker for patient with glioma by Cox analysis.

Conclusion

The expression level of KIF2C mRNA could be a potential independent marker to evaluate patient prognosis.     

Pacientes con enfermedad de Parkinson avanzada con y sin congelación de la marcha. Análisis comparativo de lesiones vasculares en resonancia magnética cerebral

Introduction

Freezing of gait (FOG) is one of the most disabling and enigmatic symptoms in Parkinson's disease. Vascular lesions, observed in magnetic resonance imaging (MRI) scans, may produce or exacerbate this symptom.

Patients and methods

The study includes 22 patients with Parkinson's disease subjects, 12 with freezing of gait and 10 without. All patients underwent an MRI scan and any vascular lesions were analysed using the modified Fazekas scale.

Results

Patients with FOG scored higher on the modified Fazekas scale than the rest of the group. Although the two groups contained the same percentage of patients with vascular lesions (50% in both groups), lesion load was higher in the group of patients with FOG. Vascular lesions in the periventricular area and deep white matter seem to be the most involved in the development of FOG.

Discussion

Vascular lesions may contribute to the onset or worsening of FOG in patients with PD. This study suggests that cerebral vascular disease should be considered in patients with FOG.     

Diffusion tensor and dynamic susceptibility contrast MRI in glioblastoma

Objective

We prospectively investigated the correlation between diffusion tensor (DTI), dynamic susceptibility contrast (DSC) perfusion MRI metrics and Ki-67 labelling index in glioblastomas.

Methods

We studied seventeen patients who were operated on for glioblastoma. DTI and DSC MRI were performed within a week prior to surgical excision. Lesion/normal ratios were calculated for the apparent diffusion coefficient (ADC), fractional anisotropy (FA), relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF) and relative mean transit time (rMTT) ratio. In the excised tumour specimens Ki-67 antigen expression was evaluated by the MIB-1 immunostaining method.

Results

A significant correlation was observed between Ki-67 index and ADC ratio (r = −0.528, p = 0.029) and FA ratio (r = 0.589, p = 0.012). rCBV and rMTT presented a trend towards significant correlation with Ki-67 index (r = 0.628, p = 0.07 and r = 0.644, p = 0.06 respectively). There was a trend towards better survival for patients with gross total tumour excision and FA values lower than 0.48 (p = 0.1 and p = 0.09 respectively). No significant correlation was found between ADC ratio, rCBV, rCBF, rMTT and overall survival.

Conclusion

ADC ratio, FA ratio, rCBV and rMTT tumour/normal tissue ratios may represent indicators of glioma proliferation. FA values may hold promise for predicting survival in patients with glioblastoma.     

Surgical resection of osteolytic calvarial lesions: Clinicopathological features

Objective

Osteolytic calvarial lesions are infrequent findings. Some cases are found incidentally during cancer staging or subsequent to unspecific symptoms. There are no standardized algorithms for the treatment of such lesions. Thus, the aim of this study was to describe the clinicopathological features and surgical outcome in various osteolytic calvarial lesions.

Material and methods

The clinical presentation, radiological imaging findings, surgical treatment and histopathological findings of 36 patients who underwent surgery for an osteolytic calvarial lesion at our institution between 1998 and 2008 were reviewed.

Results

Thirty-six osteolytic calvarial lesions were identified in 20 men and 16 women. Mean age at diagnosis was 37 years. Ten patients were children younger than 15 years. Five lesions were detected during cancer staging. Complete removal of the calvarial lesions was achieved in all patients without complications. The most common histopathological diagnosis was metastasis (n = 9), Langerhans-cell histiocytosis (n = 9), and intraosseous hemangioma (n = 5). In two asymptomatic patients, histopathological findings revealed metastases of a previously unknown tumor. In two other patients known to suffer from cancer, histopathological findings indicated intraosseous hemangioma and intraosseous meningioma, respectively. Reconstruction of the calvarial defect was performed in 24 cases with poly-methyl-methacrylate and with titanium mesh in 1 case.

Conclusions

Osteolytic calvarial lesions can be found in any age group. The histopathological examination reveals various entities, and in some instances it was not concurrent with a primary malignancy. Because surgical morbidity is low, we recommend complete resection of osteolytic calvarial lesions with reconstruction when feasible.     

Limbic encephalitis and psychosis

Objective

To report a case of limbic encephalitis (LE) presenting with psychosis.

Method

Case report.

Results

A woman with LE initially presented with acute psychotic symptoms. Magnetic resonance imaging (MRI) showed hyperintensity in bilateral temporal lobes. Paraneoplastic and autoimmune antibodies were negative, but symptoms resolved after starting methylprednisolone.

Conclusion

A greater awareness for and knowledge of LE among all disciplines could help early recognition and management of LE and avoid permanent behavioral deficits.     

Thoracic sensory level as a false localizing sign in cervical spinal cord and brain lesions

Background

In rare cases of cervical myelopathy, there may be a discrepancy between the sensory level and the site of cord lesion. This phenomenon is not well recognized. This study sought to investigate the characteristics of patients presenting with a false localizing thoracic sensory level.

Methods

The databases of the neurology clinics of two major tertiary medical centers were reviewed for all patients who presented in 2000–2010 with a main complaint of paraparesis and a thoracic sensory level. Those whose initial thoracic magnetic resonance scan showed no spinal cord pathology were included in the study.

Results

Twelve patients (mean age, 52 ± 31 years) met the study criteria. In all cases, the pathological lesion was visualized on magnetic resonance imaging of the cervical spine or brain. Eight patients had a compressive lesion of the spinal cord and 4 had demyelinating lesions. The difference between the false localizing sensory level and the level of the cervical lesion ranged from 6 to 11 segments.

Conclusion

Patients with a sensory thoracic level and normal findings on thoracic magnetic resonance imaging should be further evaluated with cervical spinal cord and, sometimes, brain imaging to search for potentially treatable lesions.     

Recomendaciones para la utilización clínica del estudio de potenciales evocados motores en la esclerosis múltiple

Objective

To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up.

Method

We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS.

Results

MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS.

Conclusions

Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space.     

Imagerie cérébrale et lithium

Objectives

Recent neuroimaging techniques like MRI, allow a better understanding of the mechanism of action of lithium. In this article, we summarize the main results about neuroimaging and lithium in bipolar disorder.

Methods

We selected relevant literature about brain imaging and lithium action in bipolar disorder.

Results and conclusions

Brain imaging studies bring evidence that lithium therapeutic effect is associated with a neurotrophic effect, especially in the grey matter and the hippocampus. They also raise hopes that we may in the future use brain imaging to measure directly brain lithium concentrations with spectroscopy and to help the clinician predict the response to lithium.     

Dilatations géantes des espaces de Virchow-Robin symptomatiques

Introduction

Perivascular spaces, known as Virchow-Robin spaces (VRS), may become massively enlarged but are usually an incidental finding. However, a few reports on patients with unusually large VRS have mentioned association with neurological symptoms. We report a series of three symptomatic patients with extremely wide Virchow-Robin spaces documented on brain magnetic resonance imaging (MRI).

Methods

We retrospectively analyzed the medical records and brain MRI of three symptomatic patients, who had been diagnosed with VRS widening.

Case reports

In all three patients, the unusual widening of the VRS was located within the subcortical white matter with asymmetric distribution. Their neurological symptoms were epilepsy and neurological deficits which correlated well with the lesions seen on the MRI. Two patients had associated white matter hyperintensities: in the first case associated gliosis and in the second case, with vascular leukoencephalopathy.

Conclusions

Enlarged symptomatic VRS are rare. The underlying pathophysiological mechanisms remain uncertain. We report three cases with symptomatic giant dilatation of the Virchow-Robin spaces.     

Brain white matter hyperintensities in migraine: Clinical and radiological correlates

Objective

Migraine is a recognised cause of brain white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI). However radiological characteristics of those in migraine are not well defined. We sought to study the radiological characteristics and factors associated with WMH in migraine.

Methods

Migraine patients who were investigated with MRI of the brain in the outpatient clinic were studied retrospectively. Two groups were delineated based on the presence or absence of WMH in MRI scans. The clinical and demographic characteristics between the two groups were compared to delineate the associations of WMH.

Results

Forty four patients were studied, out of which 19 demonstrated WMH on MRI. Frontal lobe was involved in all subjects with WMH. Infratentorial hyperintensities were not seen in any. Subcortical and deep white matter was the commonest distribution while callosal and subcallosal lesions were very rare. Family history of migraine, increasing age, and increasing headache frequency emerged as significant associations of WMH in multivariable analysis.

Conclusions

There are characteristic radiological features and clinical associations of WMH in migraine.     

Differentiation of pure vasogenic edema and tumor-infiltrated edema in patients with peritumoral edema by analyzing the relationship of axial and radial diffusivities on 3.0T MRI

Object

The purpose of this study was to analyze the relationship of axial diffusivity (AD) and radial diffusivity (RD) in peritumoral edema of high grade glioma, metastasis, and meningioma, and to differentiate tumor-infiltrated edema from pure vasogenic edema.

Materials and methods

Twenty patients with high-grade glioma and 16 with meningioma or metastatic tumor were enrolled in our study. All cases were confirmed by histopathological study. Diffusion tensor imaging (DTI) was performed in all patients. Peritumoral edema of high-grade glioma was considered tumor-infiltrated edema, and edema of meningioma or metastasis was considered pure vasogenic edema. Fractional anisotropy (FA), mean diffusivity (MD), AD, RD, regression coefficient of RD to AD (RC_RD–AD), and tumor infiltration index (TII) in tumor-infiltrated edema and pure vasogenic edema were analyzed and compared. Receiver operating characteristic (ROC) curve analysis was conducted to demonstrate their differential effectiveness.

Results

RC_RD–AD in tumor-infiltrated edema (0.724 ± 0.125) was significantly higher than that in pure vasogenic edema (0.571 ± 0.111) (P = 0.001). FA of tumor-infiltrated edema (0.175 ± 0.025) was significantly lower than that of pure vasogenic edema (0.203 ± 0.035) (P = 0.007). Other parameters showed no significant difference between the 2 types of edema. ROC curve analysis showed RC_RD–AD was the most effective parameter in distinguishing tumor-infiltrated edema from pure vasogenic edema. Using a threshold of 0.6, a sensitivity of 0.85 and specificity of 0.69 can be achieved with RC_RD–AD.

Conclusion

Analysis of the AD and RD relationship may reflect differences in diffusion characteristics of edema surrounding high-grade glioma and meningioma or metastasis, and may be helpful in detecting peritumoral infiltration in high-grade glioma.     

Forward and inverse electroencephalographic modeling in health and in acute traumatic brain injury

Objective

EEG source localization is demonstrated in three cases of acute traumatic brain injury (TBI) with progressive lesion loads using anatomically faithful models of the head which account for pathology.

Methods

Multimodal magnetic resonance imaging (MRI) volumes were used to generate head models via the finite element method (FEM). A total of 25 tissue types—including 6 types accounting for pathology—were included. To determine the effects of TBI upon source localization accuracy, a minimum-norm operator was used to perform inverse localization and to determine the accuracy of the latter.

Results

The importance of using a more comprehensive number of tissue types is confirmed in both health and in TBI. Pathology omission is found to cause substantial inaccuracies in EEG forward matrix calculations, with lead field sensitivity being underestimated by as much as ∼200% in (peri-) contusional regions when TBI-related changes are ignored. Failing to account for such conductivity changes is found to misestimate substantial localization error by up to 35 mm.

Conclusions

Changes in head conductivity profiles should be accounted for when performing EEG modeling in acute TBI.

Significance

Given the challenges of inverse localization in TBI, this framework can benefit neurotrauma patients by providing useful insights on pathophysiology.