Nadia Biassou - Academia.edu (original) (raw)

Papers by Nadia Biassou

A common task in brain image analysis includes diagnosis of a certain medical condition wherein g... more A common task in brain image analysis includes diagnosis of a certain medical condition wherein groups of healthy controls and diseased subjects are analyzed and compared. On the other hand, for two groups of healthy participants with different proficiency in a certain skill, a distinctive analysis of the brain function remains a challenging problem. In this study, we develop new computational tools to explore the functional and anatomical differences that could exist between the brain of healthy individuals identified on the basis of different levels of task experience/proficiency. Towards this end, we look at a dataset of amateur and professional chess players, where we utilize resting-state functional magnetic resonance images to generate functional connectivity (FC) information. In addition, we utilize T1-weighted magnetic resonance imaging to estimate morphometric connectivity (MC) information. We combine functional and anatomical features into a new connectivity matrix, which we term as the functional morphometric similarity connectome (FMSC). Since, both the FC and MC information is susceptible to redundancy, the size of this information is reduced using statistical feature selection. We employ off-the-shelf machine learning classifier, support vector machine, for both single-and multi-modality classifications. From our experiments, we establish that the saliency and ventral attention network of the brain is functionally and anatomically different between two groups of healthy subjects (chess players). We argue that, since chess involves many aspects of higher order cognition such as systematic thinking and spatial reasoning and the identified network is task-positive to cognition tasks requiring a response, our results are valid and supporting the feasibility of the proposed computational pipeline. Moreover, we quantitatively validate an existing neuroscience hypothesis that learning a certain skill could cause a change in the brain (functional connectivity and anatomy) and this can be tested via our novel FMSC algorithm. .

Cancer Research, 2022

Background: The incidence of breast cancer brain metastases is rising, and, these lesions in the ... more Background: The incidence of breast cancer brain metastases is rising, and, these lesions in the central nervous system (CNS) and their treatments cause physical and neurocognitive impairment. Only modest incremental advances in progression free survival have been achieved with drugs to treat CNS lesions, while nearly half of the patients who receive SRS will develop new brain metastases within 1 year. In murine models of breast cancer, we demonstrated that low doses of temozolomide (TMZ) administered in a prophylactic, metronomic fashion significantly prevented development of brain metastases. No effect, however, was seen in established brain metastases or systemic breast cancer metastases. We hypothesize that low dose, metronomic TMZ will prevent the outgrowth of brain lesions in HER2+ patients, when added to an active anti-HER2 treatment. We present here the results of the phase I trial combining T-DM1 to TMZ for the prevention of additional brain metastases after their first occ...

Electrocorticographic (ECoG) spectral patterns obtained during language tasks from 12 epilepsy pa... more Electrocorticographic (ECoG) spectral patterns obtained during language tasks from 12 epilepsy patients (age: 12^44 years) were analysed in order to identify and characterize cortical language areas. ECoG from 63 subdural electrodes (500 Hz/channel) chronically implanted over frontal, parietal and temporal lobes were examined. Two language tasks were performed. During the first language task, patients listened to a series of 50 words preceded by warning tones, and were asked to repeat each word. During a second memory task, subjects heard the 50 words from the first task randomly mixed with 50 new words and were asked to repeat the word only if it was a new word. Increases in ECoG gamma power (70^100 Hz) were observed in response to hearing tones (primary auditory cortex), hearing words (posterior temporal and parietal cortex) and repeating words (lateral frontal and anterior parietal cortex). These findings were compared to direct electrical stimulation and separate analysis of ECoG gamma changes during spontaneous inter-personal conversations. The results indicate that high-frequency ECoG reliably differentiates cortical areas associated with receptive and expressive speech processes for individual patients. Compared to listening to words, greater frontal lobe and decreased temporal lobe gamma activity was observed while speaking. The data support the concept of distributed functionally specific language modules interacting to serve receptive and expressive speech, with frontal lobe 'corollary discharges' suppressing low-level receptive cortical language areas in the temporal lobe during speaking.

Neurology, 2015

Objective: To evaluate the reliability of radiological evaluation of central nervous system (CNS)... more Objective: To evaluate the reliability of radiological evaluation of central nervous system (CNS) atrophy in multiple sclerosis (MS) and to explore its correlation with automated measurements and disability. Background: Although CNS volume loss reflects various pathologies, it is relevant in the assessment of MS because of its relationship to clinical outcomes. A radiologist’s gestalt evaluation, performed without the assistance of automated measurements, is often included in routine MRI reports, but the validity of that evaluation is unknown. Methods:Brain and spinal cord (SC) MRI scans from 35 MS cases and 6 healthy volunteers were independently evaluated for atrophy (none, definite, or unsure) by three neuroradiologists, masked to clinical data other than age. Evaluations were repeated after one week. Brain parenchymal fraction and SC area were quantified. Fleiss’s weighted kappa (K) assessed radiologist agreement. Linear regression models evaluated the correlation between the st...

Medical Physics, 2016

PURPOSE Irradiation of the lens during a neck CT may increase a patient's risk of developing ... more PURPOSE Irradiation of the lens during a neck CT may increase a patient's risk of developing cataracts later in life. Radiologists and technologists at the National Institutes of Health Clinical Center (NIHCC) have developed new CT imaging protocols that include a reduction in scan range and modifying neck positioning using a head tilt. This study will evaluate the efficacy of this protocol in the reduction of lens dose. METHODS We retrieved CT images of five male patients who had two sets of CT images: before and after the implementation of the new protocol. The lens doses before the new protocol were calculated using an in-house CT dose calculator, National Cancer Institute dosimetry system for CT (NCICT), where computational human phantoms with no head tilt are included. We also calculated the lens dose for the patient CT conducted after the new protocol by using an adult male computational phantom with the neck position deformed to match the angle of the head tilt. We also calculated the doses to other radiosensitive organs including the globes of the eye, brain, pituitary gland and salivary glands before and after head tilt. RESULTS Our dose calculations demonstrated that modifying neck position reduced dose to the lens by 89% on average (range: 86-96%). Globe, brain, pituitary and salivary gland doses also decreased by an average of 65% (51-95%), 38% (-8-66%), 34% (-43-84%) and 14% (13-14%), respectively. The new protocol resulted in a nearly ten-fold decrease in lens dose. CONCLUSION The use of a head tilt and scan range reduction is an easy and effective method to reduce radiation exposure to the lens and other radiosensitive organs, while still allowing for the inclusion of critical neck structures in the CT image. We are expanding our study to a total of 10 males and 10 females.

Radiology: Imaging Cancer, 2021

A ssessment of tumor size change in medical imaging is an essential aspect of the clinical evalua... more A ssessment of tumor size change in medical imaging is an essential aspect of the clinical evaluation of cancer treatment. Thus, precise and reliable lesion quantification is essential in response evaluation criteria in clinical oncology. The most common criteria used for tumor assessment remains Response Evaluation Criteria in Solid Tumors (RECIST). RECIST is a series of response criteria initially established in 2000 and revised in 2009 (version 1.1). Per RECIST version 1.1, up to two lymph nodes with short-axis diameter equal to or more than 1.5 cm can be selected as target lesions and be evaluated over time (1,2). Despite substantial revisions made in RECIST 1.1, some vital questions and limitations remain unsolved, including interreader and intrareader variations of measurements, improper method of tumor assessment in the setting of image-based focal treatment (chemoembolization, radiofrequency ablation), and lack of tumor size change with new cancer therapies when necrosis occurs (3-5). Adjacent nodes often merge as the disease progresses. Conversely, conglomerated nodes can split into smaller nodes when they shrink in response to treatment. In merged target lymph nodes, RECIST 1.1 calculates the longest short-axis diameter perpendicular to the longest axis of the resulting node (herein known as "short axis"), while in split target lymph nodes, RECIST 1.1 measures the sum of short-axis diameters of all the resulting nodal fragments (2). Recent advancements in imaging modalities have allowed us to measure the volume of the lesions more easily. The literature indicates that volumetric measurements represent a better prediction and outcome than linear one-dimensional or two-dimensional measurements in response evaluation of cancers (6-10). Volumetric measurement is a surrogate for the number of neoplastic cells and provides a more detailed and accurate evaluation of tumor size compared with RECIST 1.1 (8,11,12). In this study, we compared the RECIST 1.1 measurement in split and merged target lymph nodes with volumetric measurement on CT scans from clinical trials. Materials and Methods Patients In this institutional review board-approved Health Insurance Portability and Accountability Act-compliant

Frontiers in Neuroscience, 2021

Journal of Clinical Oncology, 2020

TPS2572 Background: We demonstrated that low doses of temozolomide (TMZ) administered in a prophy... more TPS2572 Background: We demonstrated that low doses of temozolomide (TMZ) administered in a prophylactic, metronomic fashion significantly prevented development of brain metastases in murine models of breast cancer. Based on these findings, we developed a secondary-prevention clinical trial. Methods: Phase I is a standard 3+3 design: T-DM1 3.6mg/kg IV every 21 days plus TMZ 30, 40 or 50 mg/m2 daily, to identify the maximum tolerated dose (MTD) of the combination, and is completing accrual, with 9 patients accrued, currently on the third and last dose level. Phase II will randomize patients to T-DM1 3.6mg/kg versus T-DM1 3.6mg/kg plus TMZ at recommended phase 2 dose (RP2D), to evaluate if addition of TMZ improves the recurrence-free incidence from distant new brain metastases at one year from 50% to 65%. Patients will undergo radiology guided lumbar puncture at baseline and after 6 weeks of treatment (C3D1) for correlative studies, brain MRI, systemic restaging CTs, and questionnaires...

Future Oncology, 2020

Brain metastases occur in up to 25–55% of patients with metastatic HER2-positive breast cancer. S... more Brain metastases occur in up to 25–55% of patients with metastatic HER2-positive breast cancer. Standard treatment has high rates of recurrence or progression, limiting survival and quality of life in most patients. Temozolomide (TMZ) is known to penetrate the blood–brain barrier and is US FDA approved for treatment of glioblastoma. Our group has demonstrated that low doses of TMZ administered in a prophylactic, metronomic fashion can significantly prevent development of brain metastases in murine models of breast cancer. Based on these findings, we initiated a secondary-prevention clinical trial with oral TMZ given to HER2-positive breast cancer patients with brain metastases after recent local treatment in combination with T-DM1 for systemic control of disease. Primary end point is freedom from new brain metastases at 1 year. (NCT03190967).

Scientific Reports, 2019

Twenty-seven previously healthy (of 36 consecutive eligible patients), HIV-negative cryptococcal ... more Twenty-seven previously healthy (of 36 consecutive eligible patients), HIV-negative cryptococcal meningoencephalitis (CM) patients underwent comprehensive neuropsychological evaluation during the late post-treatment period (1.3–4 years post diagnosis), assessing attention, language, learning, memory, visuospatial, executive function, information processing, psychomotor functioning, as well as mood symptoms. Seven of eight domains (all except attention) showed increased percentages of CM patients scoring in the less than 16th percentile range compared to standardized normative test averages, adjusted for education level and age. Comparison with a matched archival dataset of mild cognitive impairment/Alzheimer’s disease patients showed that CM patients exhibited relative deficits in psychomotor and executive function with fewer deficits in memory and learning, consistent with a frontal-subcortical syndrome. MRI evaluation at the time of testing demonstrated an association of lower neu...

AJR. American journal of roentgenology, Jan 16, 2018

Radiation exposure of the lens during neck CT may increase a patient's risk of developing cat... more Radiation exposure of the lens during neck CT may increase a patient's risk of developing cataracts. Radiologists at the National Institutes of Health worked with technicians to modify the neck CT scanning procedure to include a reduction in the scanning range, a reduction in the tube potential (kilovoltage), and a change in neck positioning using a head tilt. We objectively quantified the organ dose changes after this procedure modification using a computer simulation. We retrospectively analyzed CT images of 40 patients (20 men and 20 women) scanned before and after the procedure change. Radiation dose to the lens delivered before and after the procedure change was calculated using an in-house CT dose calculator combined with computational human phantoms deformed to match head tilt angles. We also calculated the doses to other radiosensitive organs including the brain, pituitary gland, eye globes, and salivary glands before and after the procedure change. Our dose calculations...

Translational lung cancer research, 2017

Thymic epithelial tumors (TETs) rarely metastasize to the brain. Clinico-pathologic features of T... more Thymic epithelial tumors (TETs) rarely metastasize to the brain. Clinico-pathologic features of TET patients with brain metastasis are not well described. TET patients referred for consultation or screening for clinical trials are included. Imaging to evaluate for brain metastases was performed when clinically indicated or if required for screening. Tumor tissue from brain metastases was obtained for analysis, when available. Clinical characteristics and survival was evaluated and a systematic review of the literature on brain metastases associated with TETs was performed. Fourteen TET patients with brain metastasis were identified. Median age at TET diagnosis was 53 years (range: 31-71 years). Twelve patients had thymic carcinoma and two patients had World Health Organization B3 thymoma. Median time from TET diagnosis to discovery of brain metastases was 2.5 years (range: 9 months-8.3 years). Eleven patients had extracranial, extrathoracic metastases during presentation with brain ...

The following work attempts to examine the intimate relationship that exists between the language... more The following work attempts to examine the intimate relationship that exists between the language processing system and the human brain. In particular, it investigates a specific aspect of linguistic processing, namely spoken word recognition, as assessed at its various levels, and examines its neural substrate using a non-invasive neuroimaging technique in healthy individuals. This dissertation also analyzes subtle behavioral phenomena observed during spoken word recognition that are correlated with specific neural activity in an online fashion. Importantly, this work describes the role of brain regions other than the classically defined eloquent perisylvian cortex during late aspects of lexical processing such as lexical selection and also suggests the possible role of subcortical brain regions in the early processing of speech stimuli. The claims made in this work are partially supported by data evidenced not only in human beings but also in other animal species that share similar cortico-thalamic connections as those found in the human brain. The data collected and analyzed here are then used to provide a more unified understanding of the auditory language processing difficulties seen in patients with Alzheimer\u27s disease

Neurology, 1995

We investigated phonologic production in patients with mild to moderate Alzheimer's disease (... more We investigated phonologic production in patients with mild to moderate Alzheimer's disease (AD) on a repetition task.AD patients produced significantly more speech errors than age-matched controls. AD patients' errors, unlike those of controls, resulted in the transformation of real words into pseudowords, occurred disproportionately in word-initial positions, and were not influenced by the phonologic environment. This pattern of errors suggests a lexical phonologic retrieval deficit in AD.NEUROLOGY 1995;45: 2165-2169

PURPOSE Clinicians and researchers use markers derived from diffusion tensor imaging (DTI) to ass... more PURPOSE Clinicians and researchers use markers derived from diffusion tensor imaging (DTI) to assess disease and interventions. We examined the influence of DTI imaging parameters (signal averages, gradient directions and b-values) on the DTI metrics using an anisotropic phantom. METHOD AND MATERIALS DTI data of an anisotropic phantom (Brain Innovations, Inc, Maastricht, NL) were acquired at 3T using a 2D single shot EPI sequence (80 2mm slices, 160x160 mm2 FOV, isotropic 2mm voxels). To investigate the sensitivity of DTI to the choice of b-value, images with various b-values (600-1500 s/mm2) were acquired (TR/TE=9000/56 ms). To evaluate the balance between directions and averages we limited imaging time to 13 minutes and acquired combinations of number of gradient directions (low (6), medium (15), and high (32)) and signal averages (1-8) with b-value = 900 s/mm2. Measures of fractional anisotropy (FA) and mean diffusivity (MD) were extracted from the images using NiPyPE (Neuroimagi...

CONCLUSION More accurate perfusion fraction maps can be obtained when data is acquired without th... more CONCLUSION More accurate perfusion fraction maps can be obtained when data is acquired without the confounding influence of partial volumed CSF signal. BACKGROUND Measuring perfusion fractions with diffusion weighted sequences (developed by D. Bihan in late 1980s) based on the non-linear signal characteristics with increasing b field weightings has been performed in brain studies since diffusion studies first began. However one of the more confounding issues with these measurements is due to CSF contamination in voxels subject to partial voluming. In this work we implement an inversion recovery prepulse FLAIR with optimized TR TI to remove signal from CSF prior to standard EPI based diffusion acquisitions. EVALUATION A Philips 3.0 Tesla system (Philips,Best,NL) was used to scan 5 subjects under an IRB approved normal volunteer protocol. Images were acquired using a IR GRE based EPI sequence with 6 b values; 0, 50, 150, 200, 250, 1200 protocol with TR/TI/TE of 3000/2500/60 at a voxel...

Neuropsychology, 1998

Alzheimer's disease (AD) patients with semantic memory difficulty and AD patients with relatively... more Alzheimer's disease (AD) patients with semantic memory difficulty and AD patients with relatively preserved semantic memory named pictures and judged the category membership of words and pictures of natural kinds and manufactured artifacts that varied in their representativeness. Only semantically impaired patients were insensitive to representativeness in their category judgments. AD subgroup judgments did not differ for natural kinds compared to manufactured artifacts nor for words compared to pictures. AD subgroup differences could not be explained by dementia severity, memory, reading, and visuoperception. The similarity process for relating coordinate members of a taxonomic category contributes to the normal appreciation of word and picture meaning, and this process is compromised in AD patients with semantic difficulty. Semantic memory is the long-term mental representation of the meaning underlying verbal and nonverbal representations of a concept (Jackendoff, 1983; Tulving, 1972). Many reports over the past two decades have observed deficits on tasks requiring semantic memory in patients with probable Alzheimer's disease (AD), such as naming and judging the semantic category of a test object (Bayles, Tomoeda, &

Neuropsychology, 1996

Patients with Alzheimer's disease (AD) were asked to name pictures and perform a multiplechoice w... more Patients with Alzheimer's disease (AD) were asked to name pictures and perform a multiplechoice word-picture matching task with verbs and nouns. AD patients were significantly more impaired with verbs than nouns for both naming and word-picture matching, and their patterns of semantic naming errors differed for verbs and nouns. One subgroup of AD patients was compromised on both naming and word-picture matching consistent with a semantic memory deficit. Naming was worse for verbs than for nouns in these patients, and they produced significantly fewer hierarchically related semantic substitutions for verbs than for nouns. Other AD patients without semantic memory difficulty did not demonstrate these form class-sensitive patterns. The investigators hypothesize that form class-specific effects in AD patients' naming are due in part to differences in processing verbs and nouns in semantic memory.

Neurology, 1996

We assessed language functioning in 116 age-, education-, and severity-matched patients with the ... more We assessed language functioning in 116 age-, education-, and severity-matched patients with the clinical diagnosis of Alzheimer's disease (AD), multi-infarct dementia (MID) due to small-vessel ischemic disease, or a frontotemporal form of degeneration (FD). Assessments of comprehension revealed that patients with AD are significantly impaired in their judgments of single word and picture meaning, whereas patients with FD had sentence comprehension difficulty due to impaired processing of grammatical phrase structure. Patients with MID did not differ from control subjects in their comprehension performance. Traditional aphasiologic measures did not distinguish between AD, MID, and FD. Selective patterns of comprehension difficulty in patients with different forms of dementia emphasize that language deficits cannot be explained entirely by the compromised memory associated with a progressive neurodegenerative illness.NEUROLOGY 1996;47: 183-189