F. Ghielmetti

Neurospheres Enriched in Cancer Stem–Like Cells Are Highly Effective in Eliciting a Dendritic Cell–Mediated Immune Response against Malignant Gliomas

Cancer stem-like cells (CSC) could be a novel target for cancer therapy, including dendritic cell (DC) immunotherapy. To address this, we developed experiments aimed at DC targeting of neurospheres (NS) from GL261 glioma cells because neurospheres can be enriched in CSC. We obtained murine neurospheres by growing GL261 cells in epidermal growth factor/basic fibroblast growth factor without serum. GL261-NS recapitulated important features of glioblastoma CSC and expressed higher levels of radial glia stem cell markers than GL261 cells growing under standard conditions (GL261 adherent cells, GL261-AC), as assessed by DNA microarray and real-time PCR. GL261-NS brain gliomas were highly infiltrating and more rapidly lethal than GL261-AC, as evidenced by survival analysis (P < 0.0001), magnetic resonance imaging and histology. DC from the bone marrow of syngeneic mice were then used for immunotherapy of GL261-NS and GL261-AC tumors. Strikingly, DC loaded with GL261-NS (DC-NS) cured 80% and 60% of GL261-AC and GL261-NS tumors, respectively (P < 0.0001), whereas DC-AC cured only 50% of GL261-AC tumors (P = 0.0022) and none of the GL261-NS tumors. GL261-NS expressed higher levels of MHC and costimulatory molecules (CD80 and CD86) than GL261-AC; the JAM assay indicated that DC-NS splenocytes had higher lytic activity than DC-AC splenocytes on both GL261-NS and GL261-AC, and immunohistochemistry showed that DC-NS vaccination was associated with robust tumor infiltration by CD8+ and CD4+ T lymphocytes. These findings suggest that DC targeting of CSC provides a higher level of protection against GL261 gliomas, a finding with potential implications for the design of clinical trials based on DC vaccination.

Functional Connectivity during Resting-State Functional MR Imaging: Study of the Correspondence between Independent Component Analysis and Region-of-Interest-Based Methods

BACKGROUND AND PURPOSE: The connectivity across brain regions can be evaluated through fMRI either by using ICA or by means of correlation analysis of time courses measured in predefined ROIs. The purpose of this study was to investigate quantitatively the correspondence between the connectivity information provided by the 2 techniques. MATERIALS AND METHODS: In this study, resting-state fMRI data from 40 healthy participants were independently analyzed by using spatial ICA and ROI−based analysis. To assess the correspondence between the results provided by the 2 methods, for all combinations of ROIs, we compared the time course correlation coefficient with the corresponding “ICA coactivation index.” RESULTS: A strongly significant correspondence of moderate intensity was found for 20 ICA components (r = 0.44, P < .001). Repeating the analysis with 10, 15, 25, 30, 35, and 40 components, we found that the correlation remained but was weaker (r = 0.35–0.41). CONCLUSIONS: There is a significant but not complete correspondence between the results provided by ICA and ROI−based analysis of resting-state data.

In medication-overuse headache, fMRI shows long-lasting dysfunction in midbrain areas.

The primary aim of our study was to evaluate if a group of medication‐overuse headache (MOH) patients present dysfunctions in the mesocorticolimbic dopamine circuit. The secondary aim was to disentangle the role of the medication overuse and of the acute/chronic headache in determining these alterations and to investigate their persistence.

Preoperative language lateralization in temporal lobe epilepsy (TLE) predicts peri-ictal, pre- and post-operative language performance: An fMRI study☆ , ☆☆

In patients with temporal lobe epilepsy (TLE), assessment of language lateralization is important as anterior temporal lobectomy may lead to language impairments. Despite the widespread use of fMRI, evidence of its usefulness in predicting postsurgical language performance is scant. We investigated whether preoperative functional lateralization is related to the preoperative language performance, peri-ictal aphasia, and can predict language outcome one year post-surgery. We studied a total of 72 TLE patients (42 left, 30 right), by using three fMRI tasks: Naming, Verb Generation and Fluency. Functional lateralization indices were analyzed with neuropsychological scores and presence of peri-ictal aphasia. The key findings are:1) Both left and right TLE patients show decreased left lateralization compared to controls.2) Lateralization correlates with language performance before surgery. In left TLE, decreased left lateralization correlates with better fluency performance. In right TLE, increased left lateralization during the Naming task correlates with better naming.3) Left lateralization correlates with peri-ictal aphasia in left TLE patients.4) Lateralization correlates with language performance after surgery. In a subgroup of left TLE who underwent surgery (17 left), decreased left lateralization is predictive of better naming performance at 6 and 12 months after surgery. The present study highlights the clinical relevance of fMRI language lateralization in TLE, especially to predict language outcome one year post-surgery. We also underline the importance of using fMRI tasks eliciting frontal and anterior temporal activations, when studying left and right TLE patients.

Engagement of the medial temporal lobe in verbal and nonverbal memory: assessment with functional MR imaging in healthy subjects.

BACKGROUND AND PURPOSE: The hippocampus and parahippocampal gyrus have a central role in the acquisition of new memories. Although functional MR imaging (fMRI) can provide information on the functional status of these brain regions, it has not reached widespread use in the presurgical assessment of patients undergoing temporal lobectomy. We aimed to evaluate whether simple memory-encoding paradigms could be used to elicit robust activations in the hippocampus and parahippocampal gyrus and to determine the lateralization of verbal and nonverbal memory. We also studied the relative contribution of the anterior and posterior portions of these structures. MATERIALS AND METHODS: We conducted this study on 16 healthy subjects by performing event-related fMRI using 3 memory encoding tasks with words, objects, and faces. In addition to a second-level group analysis, region-of-interest (ROI)–based measurements of the signal intensity percent change and of the percentage of activated voxels, determined at 2 thresholds, were performed. ROIs were drawn on the hippocampus and parahippocampal gyrus, divided into anterior and posterior segments. RESULTS: We found overall left-lateralized activation with words, bilateral activation with objects, and right-lateralized activation with faces. In particular, significant hippocampal activations were observed with all 3 categories of stimuli, and the head of the hippocampus was generally more engaged than its body and tail. Data on the signal intensity percent change and percentage of activated voxels are provided for each ROI and task. CONCLUSIONS: The combination of these 3 undemanding memory tasks could be considered, following appropriate validation, as a tool to assess the functional status of the medial temporal lobe in clinical settings.

Accuracy of 2-hydroxyglutarate quantification by short-echo proton-MRS at 3 T: A phantom study

PURPOSE We set out to investigate the potential confounding effect of variable concentration of N-acetyl-l-aspartate (NAA) and Glutamate (Glu) on measurement of the brain oncometabolite 2-hydroxyglutarate (2HG) using a standard MRS protocol. This issue may arise due to spectral overlap at clinical magnetic field strengths and thus complicate the usage of 2HG as a putative biomarker of gliomas bearing mutations of the isocitrate dehydrogenase (IDH) 1 and 2 genes. METHODS Spectra from 25 phantoms (50 mL falcon test tubes) containing a range of known concentrations of 2HG, NAA and Glu were acquired using a clinical 3 T scanner with a quadrature head coil, single-voxel point-resolved spectroscopy sequence with TE = 30 ms. Metabolite concentrations were estimated by linear combination analysis and a simulated basis set. RESULTS NAA and Glu concentrations can have a significant confounding effect on 2HG measurements, whereby the negative changes in concentration of these metabolites typically observed in (peri)lesional areas can lead to under-estimation of 2HG concentration with respect to spectra acquired in presence of physiological levels of NAA and Glu. CONCLUSION The confounding effect of NAA and Glu concentration changes needs to be considered: in patients, it may mask the presence of 2HG at low concentrations, however it is not expected to lead to false positives. 2HG data acquired using standard short echo-time MRS protocols should be considered with caution.

First ex vivo validation of a radioguided surgery technique with β-radiation

PURPOSE A radio-guided surgery technique with β(-)-emitting radio-tracers was suggested to overcome the effect of the large penetration of γ radiation. The feasibility studies in the case of brain tumors and abdominal neuro-endocrine tumors were based on simulations starting from PET images with several underlying assumptions. This paper reports, as proof-of-principle of this technique, an ex vivo test on a meningioma patient. This test allowed to validate the whole chain, from the evaluation of the SUV of the tumor, to the assumptions on the bio-distribution and the signal detection. METHODS A patient affected by meningioma was administered 300MBq of (90)Y-DOTATOC. Several samples extracted from the meningioma and the nearby Dura Mater were analyzed with a β(-) probe designed specifically for this radio-guided surgery technique. The observed signals were compared both with the evaluation from the histology and with the Monte Carlo simulation. RESULTS we obtained a large signal on the bulk tumor (105cps) and a significant signal on residuals of ∼0.2ml (28cps). We also show that simulations predict correctly the observed yields and this allows us to estimate that the healthy tissues would return negligible signals (≈1cps). This test also demonstrated that the exposure of the medical staff is negligible and that among the biological wastes only urine has a significant activity. CONCLUSIONS This proof-of-principle test on a patient assessed that the technique is feasible with negligible background to medical personnel and confirmed that the expectations obtained with Monte Carlo simulations starting from diagnostic PET images are correct.

Bio-Image Warehouse System: Concept and Implementation of a Diagnosis-Based Data Warehouse for Advanced Imaging Modalities in Neuroradiology

Advanced neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), chemical shift spectroscopy imaging (CSI), diffusion tensor imaging (DTI), and perfusion-weighted imaging (PWI) create novel challenges in terms of data storage and management: huge amounts of raw data are generated, the results of analysis may depend on the software and settings that have been used, and most often intermediate files are inherently not compliant with the current DICOM (digital imaging and communication in medicine) standard, as they contain multidimensional complex and tensor arrays and various other types of data structures. A software architecture, referred to as Bio-Image Warehouse System (BIWS), which can be used alongside a radiology information system/picture archiving and communication system (RIS/PACS) system to store neuroimaging data for research purposes, is presented. The system architecture is conceived with the purpose of enabling to query by diagnosis according to a predefined two-layered classification taxonomy. The operational impact of the system and the time needed to get acquainted with the web-based interface and with the taxonomy are found to be limited. The development of modules enabling automated creation of statistical templates is proposed.

Frontal cortex BOLD signal changes in premanifest Huntington disease A possible fMRI biomarker

Objective: To identify a possible functional imaging biomarker sensitive to the earliest neural changes in premanifest Huntington disease (preHD), allowing early therapeutic approaches aimed at preventing or delaying clinical onset. Methods: Sixteen preHD and 18 healthy participants were submitted to anatomical acquisitions and functional MRI (fMRI) acquisitions during the execution of the exogenous covert orienting of attention task. Due to strong a priori hypothesis, all fMRI correlation analyses were restricted to the following: (1) the frontal oculomotor cortex identified by the means of a prosaccadic task, comprising frontal eye fields and supplementary frontal eye fields; and (2) the data collected during inhibition of return, a phenomenon occurring during the executed task. In preHD, multiple regression analysis was performed between fMRI data and the probability to develop the disease in the next 5 years (p5HD). Moreover, mean blood oxygen level–dependent (BOLD) signal changes in the frontal oculomotor cortex and striatal volumes were linearly correlated with p5HD. Results: In preHD, multiple regression analysis showed that clusters of activity strongly correlated with p5HD in the right frontal oculomotor cortex. Importantly, mean BOLD signal changes of this region correlated with p5HD (r2 = 0.52). Among the considered striatal volumes, a modest correlation (r2 = 0.29) was observed in the right putamen and p5HD. Conclusion: fMRI activations in the right-frontal oculomotor cortex during inhibition of return can be considered a possible functional imaging biomarker in preHD.

Loss of heterozygosity studies in extracranial metastatic meningiomas

Although most meningiomas are slow-growing tumours associated with favourable prognosis, they often present local recurrence after surgical treatment; by contrast, extracranial metastatic meningiomas are rare, occurring in less than 1% of the cases. Risk factors for distal spread remain largely unknown. We report three cases with lung or bone metastases from intracranial recurrent meningiomas. Loss of heterozygosity (LOH) analysis on 1p, 9p, 10q, 14q, and 22q was conducted in available primary, recurrent and metastatic lesions, showing the same LOH pattern in the distal metastases and in the intracranial meningioma. LOH at 1p, 14q and 9p, known to be associated with increased aggressiveness, were found. The results highlight the potential clinical relevance of integrating histopathological studies with molecular genetic analysis in the follow-up of patients with different types of meningiomas.