Khader M Hasan

University of Texas Health Science Center at Houston · Department of Diagnostic and Interventional Imaging (DII)

Objective: To identify specific white matter tracts (WMTs) whose disruption is associated with the severity of neurogenic lower urinary tract dysfunction (NLUTD) in two independent cohorts of women with multiple sclerosis (MS) and NLUTD. Methods: Cohort 1 consisted of twenty-eight women with MS and NLUTD. The validation cohort consisted of 10 wo...

Background: Optic disc edema develops in most astronauts during long-duration spaceflight. It is hypothesized to result from weightlessness-induced venous congestion of the head and neck and is an unresolved health risk of space travel. Purpose: Determine if short-term application of lower body negative pressure (LBNP) could reduce internal jugu...

Background and purpose: Changes in cerebral perfusion occur early in relapsing and progressive multiple sclerosis (MS) patients, though whether cerebral blood flow (CBF) can be altered by therapy is unknown. We sought to characterize the time course of change in CBF (cerebral vascular reactivity [CVR]), following intravenous (IV) acetazolamide (AC...

Background : Anhedonia - a key symptom of depression - is highly associated with poorer outcomes and suicidal behavior. Alterations in the circuitry of reward-related brain regions have been robustly associated with anhedonia in unipolar depression, but not bipolar disorder (BD). We investigated white matter microstructures associated with anhedoni...

Cocaine use continues to be a significant public health problem with limited treatment options and no approved pharmacotherapies. Cognitive-behavioral therapy (CBT) remains the mainstay treatment for preventing relapse, however, people with chronic cocaine use display cognitive impairments that are associated with poor response to CBT. Emerging evi...

Background Bipolar disorder (BD) is a severe psychiatric disorder associated with structural and functional brain abnormalities, some of which have been found in unaffected relatives as well. In this study, we examined the potential role of decreased fractional anisotropy (FA) as a BD endophenotype, in adolescents at high risk for BD. Methods We i...

Importance Long-duration spaceflight induces structural changes in the brain and eye. Identification of an association between cerebral and ocular changes could help determine if there are common or independent causes and inform targeted prevention strategies or treatments. Objective To determine if there is an association between quantitative cha...

Introduction: Cognitive impairment after concussion has been widely reported, but there is no reliable imaging biomarker that predicts the severity of cognitive decline post-concussion. This study tests the hypothesis that patients with a history of concussion and persistent cognitive impairment have fractional anisotropy (FA) and mean diffusivity...

Bone marrow mononuclear cells (MNCs) attenuate secondary degeneration and enhance recovery in stroke animal models. In a nonrandomized clinical trial, we imaged 37 patients with stroke: 17 patients treated with MNCs (treated) and 20 patients who received standard of care (nontreated) at 1, 3, and 12 months onset of stroke on 3.0T MRI system. Three-...

Background and purpose: Infratentorial and spinal cord lesions are important for diagnosing and monitoring multiple sclerosis, but they are difficult to detect on conventional MR imaging. We sought to improve the detection of infratentorial and upper cervical cord lesions using composite FLAIR3 images. Materials and methods: 3D T2-weighted FLAIR...

Introduction Previous studies reveal that a newly described white matter pathway, the frontal aslant tract (FAT), connecting inferior and superior frontal gyri has a role in speech and language functions. We explored the role of this tract in a phonemic and semantic fluency tasks in a cohort of multiple sclerosis patients diagnosed with cognitive i...

Background Astronauts on long-duration spaceflight missions may develop changes in ocular structure and function, which can persist for years after the return to normal gravity. Chronic exposure to elevated intracranial pressure during spaceflight is hypothesized to be a contributing factor, however, the etiologic causes remain unknown. Purpose To...

Tract‐based spatial statistics (TBSS) of diffusion tensor imaging (DTI) studies have consistently shown diminished white matter (WM) integrity for individuals with cocaine use disorder (CUD). The present study used seed‐based d mapping (SDM) to determine the extent to which a systematic difference in the WM integrity of cocaine users may exist (as...

The human hypothalamus is at the center of the human limbic system anatomically and physiologically. The hypothalamus plays pivotal roles in controlling autonomic responses and instinctive behaviors such as regulating fear, aggression, learning, feeding behavior, circadian rhythm, and reproductive activities. The detailed anatomy of the pathways re...

As a non-limbic structure, the human thalamus is the most important modulator of the limbic system. The hypothalamus plays vital roles in the survival of species by regulating fear, learning, feeding behavior, circadian rhythm, sociosexual and reproductive activities of the limbic system through connections with the thalamus. The detailed anatomy o...

Introduction: Many cell-based therapies attenuate secondary degeneration after initial ischemic injury and enhance repair. We serially compared over time the integrity of the corticospinal tract (CST) in ischemic stroke (IS) patients treated with autologous bone marrow cells versus a prospectively collected, comparable stroke patient population not...

Background and Purpose— Stroke is the leading cause of disability in United States, and aphasia is a common sequela after a left hemisphere stroke. Functional imaging and brain stimulation studies show that right hemisphere structures are detrimental to aphasia recovery but evidence from diffusion tensor imaging is lacking. We investigated the role...

Cellular therapy is a promising investigational modality to enhance poststroke recovery. We conducted a single‐arm, phase I clinical trial to determine the safety and feasibility of intravenous (IV) administration of autologous bone marrow mononuclear cells (MNCs) after acute ischemic stroke (AIS). Patients with moderate severity of AIS underwent b...

Purpose: Perihematomal edema (PHE) occurs in patients with intracerebral hemorrhage (ICH) and is often used as surrogate of secondary brain injury. PHE resolves over time, but little is known about the functional integrity of the tissues that recover from edema. In a pig ICH model, we aimed to assess metabolic integrity of perihematoma tissues by...

Background Converging lines of evidence from diffusion tensor imaging (DTI) studies reveal significant alterations in white matter (WM) microstructure in the prefrontal cortex of chronic stimulant users compared to controls, suggesting compromised axonal microstructure and/or myelin. Methods A meta-analysis of DTI-based WM integrity was conducted...

Purpose: Ongoing post-stroke structural degeneration and neuronal loss preceding neuropsychological symptoms such as cognitive decline and depression are poorly understood. Various substructures of the limbic system have been linked to cognitive impairment. In this longitudinal study, we investigated the post-stroke macro- and micro-structural inte...

BACKGROUND AND PURPOSE Assessment of the effects of microgravity on astronauts’ brains using microstructural measures by utilizing quantitative MRI, before and after spaceflight would help understand the structural changes. METHODS Quantitative MRI data sets in 19 astronauts were acquired before and after space missions. Both diffusion tensor metr...

Purpose: Cell-based therapy offers new opportunities for the development of novel treatments to promote tissue repair, functional restoration, and cerebral metabolic balance. N-acetylasperate (NAA), Choline (Cho), and Creatine (Cr) are three major metabolites seen on proton magnetic resonance spectroscopy (MRS) that play a vital role in balancing t...

Importance Spaceflight results in transient balance declines and brain morphologic changes; to our knowledge, the effect on brain white matter as measured by diffusion magnetic resonance imaging (dMRI), after correcting for extracellular fluid shifts, has not been examined. Objective To map spaceflight-induced intracranial extracellular free water...

Chronic cocaine and alcohol use impart significant stress on biological and cognitive systems, resulting in changes consistent with an allostatic load model of neurocognitive impairment. The present study measured potential markers of allostatic load in individuals with comorbid cocaine/alcohol use disorders (CUD/AUD) and control subjects. Measures...

Text summary of additional DTI information. Details for DTI methods, metrics, and analyses. (PDF)

Data file output for the HDDM analysis. Individual and group parameter estimates, and statistical and graphical convergence tests from the Hierarchical Bayesian Drift Diffusion Model (HDDM) output of analysis of the anti-saccade data, using the Python HDDM package. For further details, see (1) manuscript text; (2) Wiecki, Sofer & Frank (2013). Fron...

Details of the penalized regression analysis with results, model fit parameters, and graphical summary. Code, outcome parameters, and graphical information for the penalized regression using the elastic net via the R packages glmnet and selectiveInference. (PDF)

Summary table of white matter clusters identified in the TBSS analyses. Details for identified significant white matter (WM) clusters (number and percent) with location of tract label, for FA, MD, and RD values from the TBSS analyses regressing WM metrics and years of cocaine use, controlling for years of alcohol use, age, sex, and education. (PDF)

BACKGROUND AND PURPOSE Ventricular enlargement in elderly raises a challenging differential diagnosis to physicians. While Alzheimer's disease is the most common form of dementia, idiopathic normal pressure hydrocephalus (iNPH) constitutes a potentially reversible syndrome. iNPH has a unique pathophysiology pertaining to cerebrospinal fluid (CSF) d...

Chronic cocaine and alcohol use impart significant stress on biological and cognitive systems, resulting in changes consistent with an allostatic load model of neurocognitive impairment. The present study measured potential markers of allostatic load in individuals with comorbid cocaine/alcohol use disorders (CUD/AUD) and control subjects. Measures...

BACKGROUND AND PURPOSE In 1948, Paul Yakovlev described an additional limbic circuit located basolateral to James Papez's circuit (1937) and included orbitofrontal cortex, amygdala, and dorsomedial nucleus of thalamus. This circuit is shown to be an important component of subcortical cognitive abilities. We aimed to demonstrate this circuit in a mu...

The mammillary bodies as part of the hypothalamic nuclei are in the central limbic circuitry of the human brain. The mammillary bodies are shown to be directly or indirectly connected to the amygdala, hippocampus, and thalami as the major gray matter structures of the human limbic system. Although it is not primarily considered as part of the human...

Background and objectiveCognitive impairment (CI) is common in multiple sclerosis (MS), but underlying mechanisms and their imaging correlates are not completely understood. The gray and white matter structures of the limbic system (LS) play crucial roles in different aspects of cognition. To investigate their role in MS related CI, and since a det...

Background and purpose: As part of its technological sophistication, the International Space Station (ISS) Program operates a robust medical surveillance schedule for its rotating 6-person crew to control the known health risks and to address knowledge gaps related to human health in space flight environment. Recent evidence on visual impairment i...

In the United States alone, 1.6 to 3.8 million people have sports-related concussions yearly. The patho-mechanisms of concussions may not be directly measured by conventional neuroimaging; advanced models may be needed to address the shortcomings of the current clinical protocols. Multimodal advanced imaging may provide more accurate diagnosis and...

Iron released after intracerebral hemorrhage (ICH) is damaging to the brain. Measurement of the content and distribution of iron in the hematoma could predict brain damage. In this study, 16 Yorkshire piglets were subjected to autologous blood injection ICH model and studied longitudinally using quantitative susceptibility mapping and R2* relaxivit...

Cortical gyrification of the brain represents the folding characteristic of the cerebral cortex. How the brain cortical gyrification changes from childhood to old age in healthy human subjects is still unclear. Additionally, studies have shown regional gyrification alterations in patients with major psychiatric disorders, such as major depressive d...

Although the thalamus is not considered primarily as a limbic structure, abundant evidence indicates the essential role of the thalamus as a modulator of limbic functions indirectly through the amygdala. The amygdala is a central component of the limbic system and serves an essential role in modulating the core processes including the memory, decis...

More than half of astronauts present with significant neuro-ophthalmic findings during 6-month missions onboard the International Space Station. Although the underlying cause of this Microgravity Ocular Syndrome is currently unknown, alterations in cerebrospinal fluid dynamics within the optic nerve sheath may play a role. In the presented study, d...

Introduction: This is a prospective clinical pilot case series. Improvement of arm and hand functions after spinal cord injury (SCI) is one of the major rehabilitation goals. Electrical stimulation of the primary motor cortex via transcranial direct current stimulation (tDCS) coupled with high-intensity repetitive motor training may have potential...

Background and aims: Pioglitazone (PIO), a potent agonist of PPAR-gamma, is a promising candidate treatment for cocaine use disorder (CUD). We tested the effects of PIO on targeted mechanisms relevant to CUD: cocaine craving and brain white matter (WM) integrity. Feasibility, medication compliance, and tolerability were evaluated. Design: Two-ar...

Objective: To serially quantify changes of iron concentration within hematomas in the intracerebral hemorrhage (ICH) pig model using non-invasive R2* and quantitative susceptibility mapping (QSM) MRI methods. Introduction: Hemolysis-related release of hemoglobin/heme/free iron after ICH causes cytotoxic injury. An accurate post hemorrhage assessmen...

Purpose: To improve the conspicuity of white matter lesions (WMLs) in multiple sclerosis (MS) using patient-specific optimization of single-slab 3D fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Materials and methods: Sixteen MS patients were enrolled in a prospective 3.0T MRI study. FLAIR inversion time and echo t...

Background and purpose: Cerebrospinal fluid (CSF) in the brain can be compartmentalized into two main divisions: ventricular CSF and subarachnoid space (sulcal CSF). Changes in CSF volumetry are seen in many neurological conditions including multiple sclerosis (MS) and found to correlate with clinical outcomes. We aimed to test the relation betwee...

Background: Cognitive impairment (CI) cannot be diagnosed by magnetic resonance imaging (MRI). Functional magnetic resonance imaging (fMRI) paradigms, such as the immediate/delayed memory task (I/DMT), detect varying degrees of working memory (WM). Preliminary findings using I/DMT showed differences in blood oxygenation level dependent (BOLD) acti...

The amygdala is known to have a role in core processes regulated by the limbic system such as motivation, memory, emotion, social behavior, self-awareness as well as certain primitive instincts. Several functional studies have investigated some of these brain tasks of the human limbic system. However, the underlying neuronal fiber connectivity of t...

Background and purpose: Distinct injuries to various limbic white matter pathways have been reported to be associated with different aspects of cognitive dysfunction in multiple sclerosis (MS). Diffusion tensor imaging (DTI) offers a noninvasive method to map tissue microstructural organization. We utilized quantitative magnetic resonance imaging...

Purpose: Postacquisition combination of three-dimensional T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images can improve the visualization of brain lesions in multiple sclerosis (MS). However, an optimal way to combine these images has not been described so far. The main objective of this study is to investigate an optimal co...

Magnetic resonance imaging data were acquired at ∼24 h and ∼3 months post-injury on mild traumatic brain injury (mTBI; n = 75) and orthopedic injury (n = 60) cohorts. The mTBI subjects were randomly assigned to a treatment group with atorvastatin or a non-treatment mTBI group. The treatment group was further divided into drug and placebo subgroups....

The human limbic system is composed of gray and white matter structures which have been known to have a role in core processes such as motivation, memory, emotion, social behavior, self-awareness as well as certain primitive instincts. Multiple functional studies investigated some of these brain tasks in human brain limbic system. However, the unde...

BACKGROUND AND PURPOSEHuman entorhinal cortex (ERC) connects the temporal neocortex with hippocampus and is essential for memory retrieval and navigation. Markedly, there have been only few quantitative MRI works on the ERC geometric measurements in pediatric and adult healthy subjects across the lifespan. Here, we sought to fill this gap in knowle...

A comprehensive analysis of the effect of lesion in-painting on the estimation of cortical thickness using magnetic resonance imaging was performed on a large cohort of 918 relapsing-remitting multiple sclerosis patients who participated in a phase III multicenter clinical trial. An automatic lesion in-painting algorithm was developed and implement...

The vertical-occipital fasciculus (VOF), historically named as "the fasciculus occipitalis verticalis of Wernicke," has been recently brought to the attention of the neuroscience community. In this study, we delineated and quantified this tract with deterministic diffusion tensor imaging protocol. Five (all males aged 24-37 years) and 10 (7 males a...

We sought to report a central T2 hypointensity within the optic nerve on 3 T MRI studies obtained as part of the NASA Flight Medicine Visual Impairment Intracranial Pressure Protocol that had not been described previously. Twenty-one astronauts, who had undergone MRI of both orbits with direct coronal T2 sequences between 2010 and 2012, were retros...

Cerebellar white matter (WM) connections to the central nervous system are classified functionally into the Spinocerebellar (SC), vestibulocerebellar (VC), and cerebrocerebellar subdivisions. The SC pathways project from spinal cord to cerebellum, whereas the VC pathways project from vestibular organs of the inner ear. Cerebrocerebellar connections...

PurposeTo quantify the change in cerebral spinal fluid (CSF) production rate and maximum systolic velocity in astronauts before and after exposure to microgravity and identify any physiologic trend and/or risk factor related to intracranial hypertension.Materials and Methods Following Institutional Review Board (IRB) approval, with waiver of inform...

Despite a wide variety of therapeutic interventions for major depressive disorder (MDD), treatment resistant depression (TRD) remains to be prevalent and troublesome in clinical practice. In recent years, deep brain stimulation (DBS) has emerged as an alternative for individuals suffering from TRD not responding to combining antidepressants, multip...

In this retrospective study we tested the hypothesis that the net effect of impaired electrical conduction and therefore increased heat dissipation in multiple sclerosis (MS) results in elevated lateral ventricular (LV) cerebrospinal fluid (CSF) diffusivity as a measure of brain temperature estimated in vivo using diffusion tensor imaging (DTI). We...

To demonstrate the efficacy of contrast enhanced magnetic resonance venography (CEMRV) using gadofosveset trisodium in the comprehensive evaluation of the intracranial and extracranial venous system. Temporal signal decay, in-plane saturation and flow artifacts were assessed in an institutional review board approved, HIPAA compliant CEMRV study of...

Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high spatial resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways....