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Results for “Structural MRI”

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At least 1,549 records · Page 86Linked to original sources
PubMed1999

Congenital hemiplegia in children at school age: assessment of hand function in the non-hemiplegic hand and correlation with MRI.

The aim of this study was to evaluate whether children with congenital hemiplegia show abnormal hand function on the non-hemiplegic side and whether this, if present, can be related to the type and extent of brain lesions on MRI. Twenty-two children with congenital hemiplegia of age ranging between 4.8 and 12.3 years, were assessed with a clinical and MRI assessment. Clinical assessment included a structured neurological examination, assessment of hand grips and the Movement Assessment Battery for Children which also includes one item assessing speed and accuracy in each hand. The results showed that 64% of the children studied showed some degree of functional impairment of the non-hemiplegic hand. Manual dexterity 1 from the Movement ABC was, in our experience, a more sensitive tool to detect minor functional abnormalities than the evaluation of hand grips. The severity of the impairment on the non-hemiplegic side was not significantly related to the severity of impairment in the hemiplegic hand (p > 0.05). In contrast, a significant association was found with the site of lesions as hand function in the non-hemiplegic hand was always normal in children with unilateral lesion and abnormal in the ones with bilateral parenchymal lesions (p < 0.05). Children with predominantly unilateral lesions but with bilateral ventricular dilatation or periventricular changes showed more variable results.

Brain↗
PubMedDate not supplied

Assessing level of consciousness and cognitive changes from vegetative state to full recovery.

Although investigations addressing cognitive recovery from the vegetative state have been reported, to date there have been no detailed studies of these patients combining both neuropsychology and functional imaging to monitor and record the recovery of consciousness. This paper describes the recovery of a specific vegetative state (VS) case. The patient (OG) remained in the vegetative state for approximately two months, increasing her level of awareness to a minimally conscious state, where she continued for approximately 70 days. In the course of the ensuing 18 months, she was able to reach an acceptable level of cognitive functioning, with partial levels of independence. Throughout this two year period, she received continuous cognitive evaluation, for which several different tools were applied including coma and low functioning scales, full cognitive batteries, and structural and functional magnetic resonance imaging (MRI). We present here preliminary data on fMRI using a word presentation paradigm before and after recovery; we also discuss the difficulty of how to determine level of consciousness using the tools currently available, and the subsequent improvement in different cognitive domains. We confirm that accurate diagnosis and proper cognitive assessment are critical for the rehabilitation of patients with disorders of consciousness.

Adult↗
PubMed2005

Physiological thresholds for irreversible tissue damage in contusional regions following traumatic brain injury.

Cerebral ischaemia appears to be an important mechanism of secondary neuronal injury in traumatic brain injury (TBI) and is an important predictor of outcome. To date, the thresholds of cerebral blood flow (CBF) and cerebral oxygen utilization (CMRO(2)) for irreversible tissue damage used in TBI studies have been adopted from experimental and clinical ischaemic stroke studies. Identification of irreversibly damaged tissue in the acute phase following TBI could have considerable therapeutic and prognostic implications. However, it is questionable whether stroke thresholds are applicable to TBI. Therefore, the aim of this study was to determine physiological thresholds for the development of irreversible tissue damage in contusional and pericontusional regions in TBI, and to determine the ability of such thresholds to accurately differentiate irreversibly damaged tissue. This study involved 14 patients with structural abnormalities on late-stage MRI, all of whom had been studied with (15)O PET within 72 h of TBI. Lesion regions of interest (ROI) and non-lesion ROIs were constructed on late-stage MRIs and applied to co-registered PET maps of CBF, CMRO(2) and oxygen extraction fraction (OEF). From the entire population of voxels in non-lesion ROIs, we determined thresholds for the development of irreversible tissue damage as the lower limit of the 95% confidence interval for CBF, CMRO(2) and OEF. To test the ability of a physiological variable to differentiate lesion and non-lesion tissue, we constructed probability curves, demonstrating the ability of a physiological variable to predict lesion and non-lesion outcomes. The lower limits of the 95% confidence interval for CBF, CMRO(2) and OEF in non-lesion tissue were 15.0 ml/100 ml/min, 36.7 mumol/100 ml/min and 25.9% respectively. Voxels below these values were significantly more frequent in lesion tissue (all P < 0.005, Mann-Whitney U-test). However, a significant proportion of lesion voxels had values above these thresholds, so that definition of the full extent of irreversible tissue damage would not be possible based upon single physiological thresholds. We conclude that, in TBI, the threshold of CBF below which irreversible tissue damage consistently occurs differs from the classical CBF threshold for stroke (where similar methodology is used to define such thresholds). The CMRO(2) threshold is comparable to that reported in the stroke literature. At a voxel-based level, however (and in common with ischaemic stroke), the extent of irreversible tissue damage cannot be accurately predicted by early abnormalities of any single physiological variable.

Adolescent↗
PubMed2002

Volumetry of temporopolar, perirhinal, entorhinal and parahippocampal cortex from high-resolution MR images: considering the variability of the collateral sulcus.

Researchers in clinical and basic neuroscience frequently target structures of the human medial temporal lobe (MTL) for volumetric analysis with magnetic resonance imaging (MRI). In neurodegenerative diseases, a precise volumetric analysis of MTL structures can assist in differential diagnosis and can be used in guiding early treatment. Also, in functional neuroimaging, exact localization is crucial for the correct interpretation of focal MTL activations with respect to specific memory functions. In presently available protocols, precise and consistent volumetric analysis of MTL structures is compromised in numerous ways. Most importantly, in order to cover all structures of the MTL, the researcher is presently forced to combine independently developed segmentation protocols for different structures from different laboratories. This approach limits anatomical precision because these protocols are based on different anatomical guidelines and descriptions that cannot easily be integrated. The segmentation approach presented in this paper was designed to address this issue by presenting segmentation guidelines for all major structures of the parahippocampal gyrus (PHG). It was developed directly to complement a volumetric protocol for hippocampus and amygdala (Pruessner et al., 2000, Cereb Cortex 10:433-442), thus allowing volumetric assessment of all major MTL structures in an integrated and consistent manner. Furthermore, it takes into consideration the neuroanatomical appearance of the collateral sulcus by presenting a method to correct the volumes of the surrounding cortices for the variability of this sulcus. The protocol was validated using MR images of 40 healthy normal control subjects (20 men and 20 women, age range 18-42 years). Intra- and interrater coefficients are presented, together with mean values for the volumes of all PHG structures, correlations with age and sex, and tests for hemispheric differences.

Adult↗
PubMed1987

Advances in noninvasive cardiovascular imaging: implications for the anesthesiologist.

We have presented a review of recent advances in medical imaging which are relevant to the practice of anesthesia and associated research. The appropriate interpretation and use of the information derived from these noninvasive technologies can prevent unnecessary morbidity and mortality. Echocardiography remains the most advanced tool for noninvasive cardiac imaging because of its applicability for most cardiac disorders and its exquisite spatial resolution. Two-dimensional systems produce real time, dynamic, qualitative assessments of cardiac chamber morphology, size, thickness, and performance. The development of transesophageal echocardiography has brought this imaging power into the operating room for use by anesthesiologists. Recently developed quantitative and color-coded Doppler techniques will reveal intracardiac flow patterns and their alterations by anesthetics and surgery. These advantages are partially offset by inherent difficulties in quantifying echocardiographic data, and the need for highly trained operators for image reproduction. Nuclear cardiology and echocardiology are highly complementary. The scintigraphic methods identify myocardium at risk for infarction, confirm infarction when present, and produce quantitative, highly reproducible estimates of ventricular filling and performance. Time required to obtain data can be very brief for first-pass techniques, and these data are ideally suited for computer processing. Equilibrium studies require a larger dose of radioactive material, but provide excellent assessment of segmental wall motion. Preoperative studies with dipyridamole and Tl can indicate the patients truly at high risk for perioperative myocardial infarction. Monitoring and intensive care efforts may be better allocated with this information. No new technology in the past decade has stirred as much interest among clinicians as magnetic resonance imaging. Like echocardiography, it uses no ionizing radiation and is entirely noninvasive. But, unlike other imaging techniques, it utilizes multiple tissue characteristics to provide quick, highly resolved, tomographic images. Since bone is invisible to the magnetic resonance scanner, tissues inside bony structures are often best revealed with MRI. Nonimaging studies, i.e., spectroscopic data not spatially encoded, may prove to be the most important research currently underway in this field. In vivo estimates of intracellular functions, enzyme kinetics, and drug kinetics and metabolism are already in progress. The effects of anesthetic in the central nervous system and other organs may be explored in ways previously not possible.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesiology↗
PubMedDate not supplied

Imaging of "iliac horns" in nail-patella syndrome.

Hereditary osteo-onychodysplasia, also known as the nail-patella syndrome (NPS), consists of a clinical tetrad of nail dysplasia, hypoplastic or absent patella, radial head dislocation, and iliac horns. Bilateral posterior iliac horns are observed only in NPS and present in >80% of patients. We describe the appearance, location, and structure of iliac horns by CT, MRI, and 3-dimensional CT reconstruction.

Adult↗
PubMedDate not supplied

MRI of early unruptured ectopic pregnancy: detection of gestational sac.

We report two cases of unruptured tubal pregnancy that were evaluated on MRI at 5 weeks' gestation. In both cases, MRI revealed gestational sac-like structures surrounded by thickened walls outside the ovaries. At the periphery of gestational sac-like structures, small amounts of fresh blood were also identified. These findings highly indicate ectopic pregnancy in a patient with elevated human chorionic gonadotropin level.

Adult↗
PubMedDate not supplied

Intraictal activation in the neocortex: a marker of the epileptogenic region.

During the course of a seizure, subdural recordings often show secondary areas which develop independent electrographic sequences that may outlast the primary seizure sequence. We reviewed the subdural data on 8 patients with intraictal secondarily activated foci (ISF). In 6 patients, ISFs were documented to be capable of generating independent seizures; ISF seizures occurred during the initial subdural monitoring period in 3, but became ictal generators only after excision of the primary focus in the other 3. Prominent interictal abnormalities were observed at the ISFs in 5 of 8 patients. The ISF in 1 patient correlated with the structural lesion on magnetic resonance imaging (MRI) scan. We believe that ISFs have significant epileptogenicity and should be resected when possible.

Adolescent↗
PubMed2006

Magnetic resonance imaging abnormalities in right ventricular outflow tract tachycardia and the prediction of radiofrequency ablation outcome.

BACKGROUND: Recent reports have shown abnormalities on cardiac magnetic resonance imaging (MRI) in patients with right ventricular outflow tract (RVOT) tachycardia. OBJECTIVES: OBJECTIVES of this study were to demonstrate abnormalities on MRI and signal-averaged ECG (SAECG) in patients with RVOT tachycardia and their correlation with the outcome of radiofrequency (RF) ablation. METHODS: We studied 41 patients with symptomatic RVOT tachycardia and 15 controls. SAECG and cardiac MRI were performed on every subject. An evaluation of structural abnormality, chamber size, function, and wall motion abnormality of the left and right ventricle was performed by MRI. Focal wall thinning was evaluated by the black blood technique and fatty infiltration was evaluated by the T1 image with and without fat suppression. RESULTS: MRI abnormalities were demonstrated in 24 (58.5%) patients with RVOT tachycardia. The abnormalities included localized wall bulging in 22 (53.7%), focal wall thinning in 10 (24.4%), and fatty replacement in 9 (22%) patients. MRI abnormality was found in only one patient in the control group (P < 0.001). Late potentials from SAECG were demonstrated in six (10.7%) patients but none in the controls (P = 0.117). Among 29 patients who underwent RF ablation, 3 patients had a failed procedure and 3 having arrhythmia recurrence needed repeated ablation. MRI abnormalities and late potentials were associated with an unfavorable outcome of RF ablation. CONCLUSIONS: MRI abnormalities were frequently found in patients with RVOT tachycardia. MRI abnormalities and late potentials can predict outcomes of RF ablation.

Catheter Ablation↗
PubMed2006

Neuroimaging of focal cortical dysplasia.

Focal cortical dysplasia (FCD) is a common cause of pharmacoresistant epilepsy that is amenable to surgical resective treatment. The identification of structural FCD by magnetic resonance imaging (MRI) can contribute to the detection of the epileptogenic zone and improve the outcome of epilepsy surgery. MR epilepsy protocols that include specific T1 and T2 weighted, and fluid-attenuated inversion recovery (FLAIR) sequences give complementary information about the characteristic imaging features of FCD; focal cortical thickening, blurring of the gray-white junction, high FLAIR signal, and gyral anatomical abnormalities. Novel imaging techniques such as magnetic resonance spectroscopy (MRS), magnetization transfer imaging (MTI), and diffusion tensor imaging (DTI) can improve the sensitivity of MR to localize the anatomical lesion. Functional/metabolic techniques such as positron emission tomography (PET), ictal subtraction single photon emission computed tomography (SPECT), functional MRI (fMRI), and magnetic source imaging (MSI) have the potential to visualize the metabolic, vascular, and epileptogenic properties of the FCD lesion, respectively. Identification of eloquent areas of cortex, to assist in the surgical resection plan, can be obtained non-invasively through the use of fMRI and MSI. Although a significant number of FCD lesions remain unidentified using current neuroimaging techniques, future advances should result in the identification of an increasing number of these cortical malformations.

Cerebral Cortex↗
PubMed1996

Reflex studies and MRI in the restless legs syndrome.

Brainstem and spinal pathways of untreated patients with idiopathic restless legs syndrome (RLS) were examined using magnetic resonance imaging (MRI), blink reflex, first and second exteroceptive suppression (ES1, ES2) of temporalis muscle, and H reflex. MRI of 25 patients elicited no structural lesions beyond age-related atrophy or white matter lesions on proton density- and T2-weighted coronal and axial images. All patients showed a normal latency of the soleus H reflex (mean +/- SD latency = 31.22 +/- 2.81 ms) and the H/M ratio was 48 +/- 17%. The duration and onset latency of the direct and indirect blink reflex responses were normal in all patients compared with those of controls (p > 0.5). There was no significant difference in ES1 and ES2 latencies or duration between patients and controls (p > 0.5). These results suggest that the etiology of RLS symptoms does not involve structural lesions.

Adult↗
PubMed1997

Conservative treatment of a partial Achilles tendon rupture with an intratendinous lesion.

The Achilles tendon is a common site of acute and overuse injuries in runners. A case is described here in which the diagnosis of a post-traumatic intratendinous lesion was based on clinical examination and magnetic resonance imaging (MRI), and where conservative treatment was given. After a 6 months follow-up, symptoms as well as the MRI verified that intra-tendinous structural abnormalities had disappeared. This case report demonstrates that conservative treatment may be sufficient to cure Achilles injury with severe structural changes inside the tendon.

Achilles Tendon↗
PubMed1991

Anterograde amnesia with fornix damage following removal of IIIrd ventricle colloid cyst.

Two patients developed anterograde amnesia following the apparently uncomplicated transcallosal-transventricular removal of a colloid cyst. Damage to the fornical columns was demonstrated on CT and MRI scans, whilst other memory related structures were entirely normal. Longitudinal neuropsychological evaluation, over 12-24 months, has revealed a very similar pattern of deficit in the two cases: verbal memory has remained persistently impaired whilst nonverbal anterograde memory has improved to some degree. Formal tests of remote public (famous faces and events) and personal autobiographical memory have supported the clinical impression that neither patient has a temporally extensive retrograde amnesia. These findings address the role of the fornix, and the dissociation of memory processes in humans.

Adult↗
PubMed1994

PET in stereotactic conditions increases the diagnostic yield of brain biopsy.

We have recently described a technique allowing routine integration of PET scan data in the planning of stereotactic brain biopsy [Levivier et al:, Neurosurgery, 1992; 31:792-797]. We now report our results in a consecutive series of 38 patients that underwent combined FDG-PET and CT-guided stereotactic biopsy between June 1991 and January 1993. Stereotactic procedures were performed according to a standard protocol in which two biopsy trajectories were used whenever possible. This yielded to a total of 78 trajectories. In 31 patients, at least 1 trajectory was defined using an abnormality visualized on PET. The histological diagnosis was obtained in all cases. The diagnostic yield of each trajectory according to the FDG uptake of PET and contrast enhancement on CT showed that most low-grade tumors were found in hypometabolic/hypodense areas, glioblastomas were all diagnosed in areas with increased FDG uptake and contrast enhancement on CT while data for anaplastic astrocytomas were heterogeneously distributed. In the present series, 6 targets defined on CT were nondiagnostic; this never occurred when targets were defined on FDG-PET. In one case of anaplastic astrocytoma, the diagnosis was only made using a target defined on PET in a normal CT area; the second trajectory was made in a contrast-enhanced area on CT and was nondiagnostic. Because only structural images such as CT or MRI are available preoperatively, we analyzed separately the benefit of FDG-PET-guided biopsy in patients who have either an enhanced- or a nonenhanced lesion on CT. CT-enhanced lesions were found in 27 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Anterior cingulate gyrus volume and glucose metabolism in autistic disorder.

OBJECTIVE: This study reports the first paired measurements of glucose metabolism and volume of the anterior cingulate gyrus in autism. METHOD: Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans of seven high-functioning autistic patients and seven sex- and age-matched normal volunteers were coregistered. After the anterior cingulate gyri were outlined on the MRI images, the volumes of the structures were measured and corrected for brain volume. The volumes were then applied to the PET images and metabolic maps were obtained. RESULTS: Right anterior cingulate area 24' was significantly smaller in relative volume, and both area 24 and area 24' were metabolically less active, in the autistic patients than in the normal subjects. CONCLUSIONS: Autism may be characterized by structural and functional alterations in the anterior cingulate gyrus.

Adolescent↗
PubMed1999

Creutzfeldt-Jakob disease diagnosable by EEG and cerebrospinal fluid analysis without brain biopsy: a case report.

This case illustrates a classic example of CJD in its clinical presentation and course and the EEG. It also shows dramatically the utility of a newly developed protein assay in the diagnosis of this disease. This assay has the potential of eliminating the need for brain biopsy in most cases, thus providing a safer diagnostic method for both staff and patients. In addition, the case points out that anatomical structural studies such as CT and MRI do not replace the utility of EEG in the comprehensive evaluation of rapid onset dementia, but rather complement the usefulness of EEG.

Cerebrospinal Fluid Proteins↗
PubMed1992

Specific neurobehavioral profile of Williams' syndrome is associated with neocerebellar hemispheric preservation.

Previous work demonstrated enlargement of the neocerebellar vermis in Williams' syndrome (WS), despite diminished volumes in the cerebral hemispheres. We present the first in vivo volumetric study of any structure within the cerebellar hemispheres. Using MRI, we identified and reliably measured the neocerebellar tonsils in WS subjects; Down's syndrome (DS) subjects matched for age, IQ, and cerebral volume; and age-matched normal controls. WS tonsils were equal in size to control tonsils and larger than DS tonsils. In proportion to the cerebrum, WS tonsils were larger than controls'. These results coincide with the remarkable neuropsychological preservation of language and affect in WS, despite general cognitive impairment. They contrast with the neocerebellar vermal hypoplasia seen in autism, with its communicative and affective deficits. Additionally, two WS subjects showed Chiari type I malformations, but the average tonsillar position in WS was not found to be different than in controls.

Adolescent↗
PubMed1993

MRI volumetric measurement of amygdala and hippocampus in temporal lobe epilepsy.

We performed MRI volumetric measurements of the amygdala (AM), the hippocampal formation (HF), and the anterior temporal lobe in a group of 30 patients with intractable temporal lobe epilepsy (TLE) and in seven patients with extratemporal lobe foci. Measurements were analyzed with a semiautomated software program and the results compared with those of normal controls and correlated with the findings of all other investigations. In particular, we compared the results with the lateralization of epileptic abnormalities in the EEG. Volumetric studies of AM and HF showed lateralization of measurable atrophy consistent with that derived from extracranial and intracranial EEG examinations. The HF volumes were more sensitive and provided a lateralization in 87%. Combined measurements of AM and HF showed lateralization in 93%, always congruent with the results of EEG lateralization. This slight but important additional improvement in discrimination justifies using AM measurements in MRI volumetric studies of mesial temporal structures. Volumetric studies combined with other currently employed noninvasive techniques may diminish the need for invasive methods of investigation in patients with TLE.

Adult↗