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PubMed2005

Integrating functional neuroimaging and human operant research: brain activation correlated with presentation of discriminative stimuli.

Results of numerous human imaging studies and nonhuman neurophysiological studies on "reward" highlight a role for frontal, striatal, and thalamic regions in operant learning. By integrating operant and functional neuroimaging methodologies, the present investigation examined brain activation to two types of discriminative stimuli correlated with different contingencies. Prior to neuroimaging, 10 adult human subjects completed operant discrimination training in which money was delivered following button pressing (press-money contingency) in the presence of one set of discriminative stimuli, and termination of trials followed not responding (no response-next trial contingency) in the presence of a second set of discriminative stimuli. After operant training, subjects were instructed to memorize a third set of control stimuli unassociated with contingencies. Several hours after training, functional magnetic resonance imaging was performed while subjects viewed discriminative and control stimuli that were presented individually for 1,500 ms per trial, with stimulus presentations occurring, on average, every 6 s. Activation was found in frontal and striatal brain regions to both sets of discriminative stimuli relative to control stimuli. In addition, exploratory analyses highlighted activation differences between discriminative stimuli. The results demonstrate the utility of coupling operant and imaging technologies for investigating the neural substrates of operant learning in humans.

Adolescent↗
PubMed2002

Structural and functional neuroimaging in Alzheimer's disease: an update.

The field of neuroimaging has made several recent advances understanding Alzheimer's disease, a debilitating disease which affects approximately 4 million people in the United States [1]. Despite recent therapeutic advances, available treatments at present are aimed primarily at slowing progression of the disease rather than halting it completely or reversing its progression. Early detection of the disease has, therefore, been a major focus of a variety of neuroimaging techniques, including Positron Emission Tomography (PET), functional Magnetic Resonance Imaging (fMRI), and structural MRI. Recently, these techniques have also been found to be useful in monitoring cognitive and pathological progression of the disease, as well as monitoring response to clinical intervention treatment. A methodology review will be included here as well as a critical evaluation of the advantages and disadvantages of the various techniques.

Alzheimer Disease↗
PubMed2004

Advances in neuroimaging for HIV-1 associated neurological dysfunction: clues to the diagnosis, pathogenesis and therapeutic monitoring.

Persons with advanced human immunodeficiency virus type one (HIV-1) infection seek medical advice for a wide range of neurological disorders including, but not limited to, peripheral neuropathy, toxoplasmosis, cryptococcal meningitis, cytomegalovirus retinitis progressive multifocal leukoencephalopathy, lymphoma and dementia. The diagnosis of HIV-1-associated dementia (HAD) induced as a direct consequence of HIV infection of the brain comes commonly by exclusion. Diagnostic decisions can often be clouded by concomitant depression, motor impairments, and lethargy that follow debilitating immune suppression and weight loss. Indeed, cognitive, motor and behavior abnormalities underlie a variety of neurological dysfunctions associated with advanced HIV-1 infection. Thus, even combinations of clinical, laboratory and neuroimaging tests [for example, magnetic resonance imaging (MRI), computed tomography (CT), single photon emission computed tomography (SPECT) and positron emission tomography (PET)] often fail to provide conclusive diagnostic information. Nonetheless, the recent development of quantitative MR spectroscopic imaging has improved diagnostic possibilities for HAD. We are pleased to discuss these developments as well as taking a forward look into what will soon be made available to improve neuroimaging diagnostic precision. New MR and SPECT testing are being developed in our laboratories and elsewhere both for animal model systems and in humans with HIV-1 disease. Such tests can facilitate dynamic measures of HIV-1 neuropathogenesis providing information for disease events that even 2 years ago were unattainable.

AIDS Dementia Complex↗
PubMed1990

Neuroimaging of disseminated germ cell neoplasms.

The purpose of this study was to determine the role of neuroimaging in the management of patients with metastatic germ cell tumors. Retrospective evaluation of 299 patients treated in 1986 and 1987 for initial presentation or recurrence of testicular, retroperitoneal, and mediastinal germ cell tumors was performed to determine indications for neuroimaging, frequency and site of CNS metastases, and occurrence of other CNS abnormalities. Sixty-six patients required CNS imaging with myelography, CT, or MR. Studies were normal in 24 patients. Twenty patients had CNS metastases including 11 with intracranial metastases, eight with spine lesions, and one with both brain and spine involvement. Sixteen had cerebral or cerebellar atrophy of unclear origin and functional significance. Two patients had ventriculomegaly without symptoms of hydrocephalus. Four patients had questionable lesions that were never confirmed. None of the 25 asymptomatic patients with elevated serum tumor markers had brain metastases. Fifteen of 17 patients with focal neurologic deficits and three of six patients with seizures had CNS metastases. CNS imaging to detect germ cell tumor metastases is most useful in the presence of neurologic deficits or seizures but is not useful in patients with unexplained elevation of serum tumor markers in the absence of neurologic deficits.

Adolescent↗
PubMed1992

Rasmussen's encephalitis: neuroimaging findings in four patients.

Rasmussen's encephalitis is a devastating disease of childhood causing progressive neurologic deficits and intractable seizure activity. Patients frequently have episodes of epilepsia partialis continua and, much less frequently, generalized status epilepticus. The seizures are intractable despite aggressive medical management. In advanced cases, hemispherectomy appears to be the only option to control the seizures. Permanent physical and mental impairments are inevitable. The cause of this disease is unknown, although pathologic specimens demonstrate nonspecific changes that are compatible with viral encephalitis. The progressive brain damage is typically so insidious in onset and gradual in course that it is difficult to make an accurate diagnosis on the basis of clinical evidence. We retrospectively evaluated the CT, xenon CT, positron emission tomographic, and MR neuroimaging findings in four young patients with pathologically suspected Rasmussen's encephalitis (three patients had CT scans, two had xenon CT scans, two had MR scans, and one had a positron emission tomogram). All studies showed abnormalities of the involved cerebral hemisphere: CT and MR revealed nonspecific atrophy, xenon CT showed decreased cerebral blood flow, and positron emission tomography revealed a hypometabolic state. Rasmussen's encephalitis is a diagnosis of exclusion; however, the information obtained from neuroimaging studies in combination with the clinical course should suggest this disorder.

Adolescent↗
PubMed1994

Neuroimaging in patients with olfactory dysfunction.

This review summarizes neuroimaging findings in patients with olfactory dysfunction. Neuroimaging techniques offer a valuable means for evaluating and distinguishing disorders of olfaction. The new or refined techniques make it possible to pinpoint the anatomic and pathologic changes of many disorders of the sinonasal cavity and brain that cause olfactory deficits. From an anatomic point of view, the causes of olfactory deficits generally can be classified as peripheral or central (intracranial). In the assessment of the peripheral causes, CT and MR imaging reveal anatomic information and structural changes, enable a differential diagnosis, and provide a road map for surgical intervention. In the evaluation of the central causes, MR imaging, positron emission tomography, or single-photon emission computed tomography can provide the links between olfactory dysfunction and structural or functional changes in the brain.

Brain Diseases↗
PubMed2000

Report of three cases of Alzheimer's disease with focal motor symptoms: clinical correlates of neuroimaging findings.

We report clinical and neuroimaging findings for three patients suffering from Alzheimer's disease (AD) with focal motor symptoms. These patients initially showed cognitive deficits and subsequently featured myoclonus and awkward movements in the unilateral upper limb while progressing to paresis. Paresis was noted in the unilateral upper limb. All patients held the unilateral arm flexed at the wrist and elbow, closely adducted to the body and the hand fisted and pronated. No signs of cerebellar ataxia, sensory disturbance or long tract signs were observed, nor any of the initial non-cognitive behavioural changes typical of frontotemporal dementia. EEGs of these patients showed marked slowing of basic activity without epileptic discharges. MRIs showed progressive brain atrophy in the contralateral frontoparietal lobes as well as the hippocampal formation. Cases 2 and 3 featured extensive long T2 lesions on MRI. 99mTc-HMPAO-SPECT revealed blood flow hypoperfusion in the corresponding regions. The cerebellum and brain stem showed neither morphological abnormalities nor blood flow hypoperfusion. On the basis of these clinical and neuroimaging observations, the focal motor symptoms were attributed to contralateral frontoparietal cortical atrophy with or without white matter lesion.

Aged↗
PubMed2001

Structural neuroimaging studies in late-life depression: a review.

Which patients presenting with depression in late life will progress to a dementia syndrome has been an important research question in recent times. In this paper we review selectively structural neuroimaging investigations of late-life depression (LLD) that have been performed over the past two decades. These studies indicate that there are neuroimaging changes commonly observed in LLD patients when compared to normal controls. Findings include ventricular enlargement and sulcal widening, and reduction in volume size of frontal lobes, hippocampus and caudate nucleus. White matter lesions are more common in depressed subjects and tend to be more severe. Some studies report these changes to be more pronounced in patients who present with late-onset depression (LOD) but this has been contradicted by other studies. Preliminary work suggests that these changes may be associated with a poor prognosis but there is a dearth of systematic, well-controlled longitudinal studies.

Aged↗
PubMed2002

[Neuroimaging--recent issues and future progresses].

Recent advances in the technology of non-invasive neuroimaging techniques, include X-ray CT, magnetic resonance imaging, positron CT, etc. The trend of neuroimaging is from the diagnosis of the brain structural change to the functional localization of the brain function with accurate topographical data. Brain activation studies disclosed the responsible regions in the brain for various kinds of paradigms, including motor, sensory, cognitive functions. Another aspect of brain imaging shows the pathophysiological changes of the neurological disorders, such as Alzheimer's disease by abnormal CBF or metabolism changes. It is very important to note that the neurotransmitter receptor imaging is now available for various kinds of transmitters. We recently developed a new tracer for nicotinic type acetylcholine receptor, which might be involved in the pathophysiology of Alzheimer's disease and its treatment. In the near future, we will be able to visualize the proteins in the brain such as amyloid protein, which will make us to diagnose Alzheimer's patients accurately, and with respect to neuroscience research, not only neuronal functional localizations but also relationship between them will become important to disclose the functional aspects of the brain.

Alzheimer Disease↗
PubMed1994

Diffuse bilateral cerebral astrocytomas with atypical neuroimaging studies.

The authors describe the clinical behavior of eight patients with cerebral astrocytomas, in whom computerized tomography (CT) or magnetic resonance (MR) imaging of the brain was characterized by diffuse bilateral cerebral hemisphere tissue density abnormalities and minimal focal mass effect. Five patients were newly diagnosed, and three others had been treated for focal low-grade astrocytoma. Histological diagnoses included anaplastic astrocytoma (three patients), low-grade astrocytoma (three patients), glioblastoma (one patient), and gliosis with later development of glioblastoma (one patient). In five patients, brain tumor was not suspected from the neuroimaging studies, the findings of which were mistaken for radiation leukoencephalopathy, vasogenic edema, or multiple sclerosis. Serial CT scans or MR images undertaken over intervals of 3 to 184 weeks showed progression of abnormal tissue densities in seven patients and multifocal contrast-enhancing masses developed on CT scan in two patients. An autopsy in each of four patients showed diffuse cerebral infiltration by astrocytoma. It is concluded that neuroimaging studies in some patients with diffusely infiltrating cerebral astrocytoma are atypical for neoplasm and can be mistaken for other diseases, especially those that predominantly affect cerebral hemisphere white matter.

Adolescent↗
PubMed1995

Meningiomas arising from the falcotentorial junction. Clinical features, neuroimaging studies, and surgical treatment.

Meningiomas arising from the falcotentorial junction are extremely rare. The authors describe the clinical features, neuroimaging studies, and results of surgical treatment of meningiomas of the falcotentorial junction and clarify the characteristics of this lesion based on a review of the literature and seven patients treated at their institution. The most common symptoms resulted from intracranial hypertension. Upward-gaze palsy appeared in only one patient. Computerized tomography (CT) showed no specific findings, but there was no evidence of edema around the tumor. Magnetic resonance (MR) imaging revealed a round, smooth-bordered mass with a peritumoral rim, without edema, and showing marked contrast enhancement. The multiplanar capability of MR imaging delineated the relationship between the tumor and adjacent structures better than did CT. Detailed knowledge of the vascular structures, especially evidence of occlusion of the galenic venous system and the development of collateral venous channels, is critical for successful surgery; stereoscopic cerebral angiography is necessary to achieve this aim. The seven patients described developed five types of collateral venous channels: through the basal vein of Rosenthal to the petrosal vein, through the veins on the medial surface of the parietal and occipital lobes to the superior sagittal sinus, through superficial anastomotic veins, through veins of the posterior fossa to the transverse or straight sinus, and through the falcian veins to the superior sagittal sinus. The first three types mainly developed after occlusion of the galenic system. The tumors were removed through the occipital transtentorial approach with a large window at the posterior part of the falx. A favorable prognosis for patients undergoing surgical treatment of falcotentorial junction meningiomas can be expected if detailed neuroimaging studies and microsurgical techniques are used.

Adult↗
PubMed2006

A functional neuroimaging investigation of deep brain stimulation in patients with obsessive-compulsive disorder.

OBJECT: Deep brain stimulation (DBS) of the ventral [anterior internal] capsule/ventral striatum (VC/VS) is under investigation as an alternative to anterior capsulotomy for severe obsessive-compulsive disorder (OCD). In neuroimaging studies of patients with OCD, dysfunction in the orbitofrontal and anterior cingulate cortex, striatum, and thalamus has been identified; and modulation of activity in this circuit has been observed following successful nonsurgical treatment. The purpose of the current study was to test hypotheses regarding changes in regional cerebral blood flow (rCBF) during acute DBS at the VC/VS target in patients with OCD who were participating in a clinical DBS trial. METHODS: Six patients enrolled in a DBS trial for OCD underwent positron emission tomography to measure rCBF; the rCBF measured during acute DBS at high frequency was then compared with those measured during DBS at low frequency and off (control) conditions. On the basis of neuroanatomical knowledge about the VC/VS and neuroimaging data on OCD, the authors predicted that acute DBS at this target would result in modulation of activity within the implicated frontal-basal ganglia-thalamic circuit. Data were analyzed using statistical parametric mapping. In a comparison of acute high-frequency DBS with control conditions, the authors found significant activation of the orbitofrontal cortex, anterior cingulate cortex, striatum, globus pallidus, and thalamus. CONCLUSIONS: Acute DBS at the VC/VS target is associated with activation of the circuitry implicated in OCD. Further studies will be necessary to replicate these findings and to determine the neural effects associated with chronic VC/VS DBS. Moreover, additional data are needed to investigate whether pretreatment imaging profiles can be used to predict a patient's subsequent clinical response to chronic DBS.

Adult↗
PubMed2006

Comparison between neuroimaging classifications and histopathological diagnoses using an international multicenter brain tumor magnetic resonance imaging database.

OBJECT: The aim of this study was to estimate the accuracy of routine magnetic resonance (MR) imaging studies in the classification of brain tumors in terms of both cell type and grade of malignancy. METHODS: The authors retrospectively assessed the correlation between neuroimaging classifications and histopathological diagnoses by using multicenter database records from 393 patients with brain tumors. An ontology was devised to establish diagnostic agreement. Each tumor category was compared with the corresponding histopathological diagnoses by dichotomization. Sensitivity, specificity, positive and negative predictive values (PPVs and NPVs, respectively), and the Wilson 95% confidence intervals (CI) for each were calculated. In routine reporting of MR imaging examinations, tumor types and grades were classified with a high specificity (85.2-100%); sensitivity varied, depending on the tumor type and grade, alone or in combination. The recognition of broad diagnostic categories (neuroepithelial or meningeal lesions) was highly sensitive, whereas when both detailed type and grade were considered, sensitivity diverged, being highest in low-grade meningioma (sensitivity 100%, 95% CI 96.2-100.0%) and lowest in high-grade meningioma (sensitivity 0.0%, 95% CI 0.0-65.8%) and low-grade oligodendroglioma (sensitivity 15%, 95% CI 5.2-36.0%). In neuroepithelial tumors, sensitivity was inversely related to the precision in reporting of grade and cellular origin; "glioma" was a frequent neuroimaging classification associated with higher sensitivity in the corresponding category. The PPVs varied among categories, in general being greater than their prevalence in this dataset. The NPV was high in all categories (69.8-100%). CONCLUSIONS: The PPVs and NPVs provided in this study may be used as estimates of posttest probabilities of diagnostic accuracy using MR imaging. This study targets the need for noninvasively increasing sensitivity in categorizing most brain tumor types while retaining high specificity, especially in the differentiation of high- and low-grade glial tumor classes.

Adolescent↗
PubMed2005

Dural ossification associated with cervical ossification of the posterior longitudinal ligament: frequency of dural ossification and comparison of neuroimaging modalities in ability to identify the disease.

OBJECT: The authors' goal in this study was to understand the frequency and pattern of dural ossification (DO, and to evaluate the effectiveness of neuroimaging modalities used to identify this disease in association with ossification of the posterior longitudinal ligament (OPLL). METHODS: One hundred eleven patients with OPLL underwent anterior procedures. Of these patients, 17 (15.3%) had associated ossification of the dura mater. There were 10 cases of DO in the 94 patients with segmental OPLL and seven in the 17 patients with nonsegmental OPLL (seven continuous and 10 mixed-type OPLL). Retrospective evaluation of DO was performed by examining plain x-ray films, polytomography studies, computerized tomography (CT) scans, and magnetic resonance (MR) images. A positive correlation was found between the type of OPLL and the frequency of DO (p < 0.01). The DO was classified into the following three types according to shape: 1) isolated type, 2) double-layer type, and 3) en bloc type, based on its relationship with OPLL. There were 10 lesions of the double-layer type, four en bloc type, and three isolated type; the double-layer pattern of DO was the most common. All DOs as well as OPLLs (17 cases) were identified using bone-window CT scanning. Polytomography was used successfully to identify all 12 OPLLs, whereas DO was recognized in seven of the 12 cases. Magnetic resonance imaging could not identify DO (none of the 17 cases), although OPLL was identified on MR imaging in 12 of the 17 cases. CONCLUSIONS: Three patterns of DO associated with OPLL, that is, isolated, double-layer, and en bloc types, were confirmed by retrospective analysis of neuroimaging findings. Nonsegmental OPLL was likely to be accompanied by DO. Bone-window CT scanning was most useful for identification of DO as well as OPLL, whereas MR imaging was ineffective in recognizing DO.

Adult↗
PubMed2006

Neuroimaging studies of serotonin gene polymorphisms: exploring the interplay of genes, brain, and behavior.

Because of the unique ability it provides to investigate information processing at the level of neural systems, functional neuroimaging is a powerful tool to explore the relationship between genes, brain, and behavior. Recently, functional neuroimaging has provided dramatic illustrations of how a promoter polymorphism in the human serotonin transporter gene, which has been weakly related to several dimensions of emotional behaviors (such as neuroticism and anxiety traits), is strongly related to the engagement of neural systems--namely, the amygdala and subgenual prefrontal cortex, subserving emotional information processing. This review will outline the experimental strategy by which these genetic effects on brain function have been explored and highlight the effectiveness of this strategy to delineate biological pathways and mechanisms contributing to the emergence of individual differences in brain function that potentially bias behavior and risk for psychiatric illness.

Animals↗
PubMed2002

Role of neuroimaging in the management of seizure disorders.

Neuroimaging is one of the most important advances made in the past decade in the management of seizure disorders. Magnetic resonance imaging (MRI) has increased substantially the ability to detect causes of seizure disorders, to plan medical or surgical therapy, and to prognosticate the outcome of disorders and therapy. However, MRI must be performed with techniques that will maximize the detection of potentially epileptogenic lesions, especially in candidates for epilepsy surgery. Functional imaging has an established role in evaluating patients for epilepsy surgery. It is relied on when results from standard diagnostic methods, such as clinical information, electroencephalography, and MRI, are insufficient to localize the seizure focus. Also, functional imaging is a reportedly reliable alternative to invasive methods for identifying language, memory, and sensorimotor areas of the cerebral cortex. Despite the availability of multimodality imaging, the epileptogenic zone is not determined solely by a single imaging modality. Evidence and experience have shown that concordance of results from clinical, electrophysiologic, and neuroimaging studies is needed to identify the epileptogenic zone accurately. With modern techniques in image processing, multimodality imaging can integrate the location of abnormal electroencephalographic, structural, and functional imaging foci on a "map" of the patient's brain. Computer image-guided surgery allows surgically exact implantation of intracranial electrodes and resection of abnormal structural or functional imaging foci. These techniques decrease the risk of morbidity associated with epilepsy surgery and enhance the probability of postsurgical seizure control.

Adolescent↗
PubMedDate not supplied

[Approximation to the diagnosis of congenital metabolic disorders with neuroimaging].

Inherited metabolic diseases (IMD) have a variable clinical and biological expression. In the last few years neuroimaging (MR, spectroscopic MR, PET, SPECT) have demonstrated the neurological impairment in some IMD. Biochemical analysis of the brain is possible due to spectroscopy MR. Neuroimaging in the IMD is not always definite but can frequently demonstrate an impairment in gray or white matter, basal ganglia, cerebellum or brain stem. In our article we analyze the different involvement of the central nervous system structures in IMD. On the other hand we review some brain malformations that can be related to IMD.

Brain↗
PubMedDate not supplied

[Electro-clinical and neuroimaging studies in epilepsy in elderly patients].

INTRODUCTION: Due to the aging population in developed countries, epidemiological studies show an increasing tendency to the prevalence of epilepsy in the elderly. PATIENTS AND METHODS: During 54 months, we have studied the electroclinical and neuroimaging features in outpatients older than 60, with active epilepsy. Every patient was interviewed by one of the authors. Then, we have reviewed the medical records about the clinical features, EEG and neuroimaging (NI) studies and seizures frequency (SF) outcome. Differences in crude proportions were assessed by chi 2 test for independence by 2 x 2 tables. RESULTS: The study was been performed in 78 patients with 70.3 +/- 7.3 years of mean age at review. Partial seizures were significantly related with an higher SF at onset and, in the series of complex partial seizures was more frequent a temporal EEG topography. There was predominance of men, NI abnormal, symptomatic etiology and SF at onset > or = 1 by day in that patients who started their epilepsy after 60 years. A 51.3% was seizures-free in the last year and in 80% the SF was improved a 50% or more from the beginning. CONCLUSION: A significantly greater percentage of patients remained with seizures in four cases: in those with a SF at onset greater than 1 every day, in those suffering complex partial seizures, in women and in patients with temporal EEG topography.

Aged↗