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At least 883 records · Page 49Linked to original sources
PubMed1997

[The sonarographic diagnosis of prostatic and periprostatic cysts on high resolution transrectal ultrasound imaging].

The symptoms of prostatic and periprostatic cysts are nonspecific and digital rectal examination has no definite findings detected. The conventional radiological plain film cannot define the relationship of a cyst to the surrounding structures. The use of MRI as a means in detection is too expensive. To solve these problems, we detected 118 cysts in 73 patients by transrectal ultrasound (TRUS) and discussed the TRUS imaging findings of various prostate and periprostate cysts with illustrations from our clinical practice. We suggest that TRUS can be used routinely, because its distinct advantage of high resolution for minute nodular or cystic lesion detection with high quality image demonstrates the relationship of surrounding structures, and provides an outstanding novel diagnostic modality.

Adult↗
PubMed2001

The importance of routine magnetic resonance imaging in trigeminal neuralgia diagnosis.

The aim of the study was to determine the frequency of structural lesions diagnosed on magnetic resonance imaging (MRI) in a sample of patients with trigeminal neuralgia (TN) and to compare history and clinical features between the groups with and without structural lesions. Clinical records and MRI findings of 42 consecutive patients diagnosed with TN at the National Dental Centre, Singapore, and who underwent routine MRI examinations at diagnostic workup between April 1997 and March 1999 were retrospectively studied. Of these, 6 (14.3%; 95% confidence interval, 0 to 28.8%) were diagnosed with an associated structural lesion. Mean age of the group with structural lesions was 53.3 years (standard deviation, 10.9 years) at presentation, there was female predominance (M:F = 1:2), and all (100.0%) gave a typical pain history and had unilateral involvement of a single division of the trigeminal nerve. Two patients (33.3%) had other cranial nerve abnormalities. Three patients (50.0%) had complete, 2 patients (33.3%) had partial, and 1 patient (16.7%) had poor response to medical therapy. None of these variables was statistically different from the group without structural lesions (cranial nerve abnormalities were not compared). In conclusion, the frequency of structural lesions associated with TN in our sample was relatively high. It is not possible to reliably identify high risk patients for selective MRI indication on the basis of history and clinical features. It may be prudent to consider routine MRI for all patients with TN to exclude structural lesions.

Adult↗
PubMed1997

Structural changes in the brain of patients with bipolar affective disorder by MRI: a review of the literature.

1. Current literature was searched to evaluate the use of magnetic resonance imaging in patients with bipolar disorder. 2. The presence of white matter hyperintensities, differences in temporal lobe and hippocampal structures, and ventricular enlargement in patients with bipolar disorder was assessed. 3. Further use of MRI in patients with bipolar disorder is reviewed.

Bipolar Disorder↗
PubMed2005

Changes in gray matter volume in patients with bipolar disorder.

BACKGROUND: Several lines of evidence suggest the presence of neurofunctional abnormalities in patients with bipolar disorder. These functional abnormalities may stem from structural pathology in these or connected brain regions. Previous studies have generally used a region of interest (ROI) approach to study morphologic changes in bipolar disorder with inconsistent findings among research groups, which may reflect differences in how ROIs are defined. Voxel based morphometry (VBM) allows a more exploratory analysis without the necessity for predefined anatomic boundaries. In this study we utilized VBM to compare gray matter volume between groups of bipolar and healthy subjects. METHODS: Thirty-two patients with bipolar disorder and 27 healthy subjects participated in structural magnetic resonance imaging (MRI) scans. MRI images were segmented, normalized to a standard stereotactic space, and compared on a voxel-by-voxel basis using statistical parametric mapping. RESULTS: Bipolar subjects showed increased gray matter in several regions including portions of anterior cingulate, ventral prefrontal cortex, fusiform gyrus and parts of the primary and supplementary motor cortex. Bipolar subjects showed decreased gray matter volume in superior parietal lobule. CONCLUSIONS: These data support suggestions that neurofunctional deficits are related to structural brain abnormalities in patients with bipolar disorder. The increased gray matter observed in several regions suggests that some affected areas may demonstrate volumetric expansion, at least in some patient populations.

Adult↗
PubMed1993

Magnetic resonance imaging of the brain in idiopathic hypogonadotropic hypogonadism.

Magnetic resonance imaging (MRI) of the pituitary, hypothalamus and olfactory sulci was performed in 40 patients with idiopathic hypogonadotropic hypogonadism (IHH). Twelve of these patients had an impaired sense of smell (Kallmann's syndrome). Sagittal and coronal imaging revealed no morphological abnormalities in the hypothalamic-pituitary region. On axial imaging rudimentary, hypoplastic or aplastic olfactory sulci were found in eight cases. All patients with olfactory sulcal abnormalities had associated hyposmia (one case) or anosmia (seven cases). Structural defects identifiable on MRI were present only in 20 per cent of patients with IHH.

Adult↗
PubMed2024

Free-water: A promising structural biomarker for cognitive decline in aging and mild cognitive impairment.

Diffusion MRI derived free-water (FW) metrics show promise in predicting cognitive impairment and decline in aging and Alzheimer's disease (AD). FW is sensitive to subtle changes in brain microstructure, so it is possible these measures may be more sensitive than traditional structural neuroimaging biomarkers. In this study, we examined the associations among FW metrics (measured in the hippocampus and two AD signature meta-ROIs) with cognitive performance, and compared FW findings to those from more traditional neuroimaging biomarkers of AD. We leveraged data from a longitudinal cohort (nparticipants = 296, nobservations = 870, age at baseline: 73 ± 7 years, 40% mild cognitive impairment [MCI]) of older adults who underwent serial neuropsychological assessment (episodic memory, information processing speed, executive function, language, and visuospatial skills) and brain MRI over a maximum of four time points, including baseline (n = 284), 18-month (n = 246), 3-year (n = 215), and 5-year (n = 125) visits. The mean follow-up period was 2.8 ± 1.3 years. Structural MRI was used to quantify hippocampal volume, in addition to Schwarz and McEvoy AD Signatures. FW and FW-corrected fractional anisotropy (FAFWcorr) were quantified in the hippocampus (hippocampal FW) and the AD signature areas (SchwarzFW, McEvoyFW) from diffusion-weighted (dMRI) images using bi-tensor modeling (FW elimination and mapping method). Linear regression assessed the association of each biomarker with baseline cognitive performance. Additionally, linear mixed-effects regression assessed the association between baseline biomarker values and longitudinal cognitive performance. A subsequent competitive model analysis was conducted on both baseline and longitudinal data to determine how much additional variance in cognitive performance was explained by each biomarker compared to the covariate only model, which included age, sex, race/ethnicity, apolipoprotein-ε4 status, cognitive status, and modified Framingham Stroke Risk Profile scores. All analyses were corrected for multiple comparisons using an FDR procedure. Cross-sectional results indicate that hippocampal volume, hippocampal FW, Schwarz and McEvoy AD Signatures, and the SchwarzFW and McEvoyFW metrics are all significantly associated with memory performance. Baseline competitive model analyses showed that the McEvoy AD Signature and SchwarzFW explain the most unique variance beyond covariates for memory (ΔRadj 2 = 3.47 ± 1.65%) and executive function (ΔRadj 2 = 2.43 ± 1.63%), respectively. Longitudinal models revealed that hippocampal FW explained substantial unique variance for memory performance (ΔRadj 2 = 8.13 ± 1.25%), and outperformed all other biomarkers examined in predicting memory decline (pFDR = 1.95 x 10-11). This study shows that hippocampal FW is a sensitive biomarker for cognitive impairment and decline, and provides strong evidence for further exploration of this measure in aging and AD.

Alzheimer’s disease (AD)↗
PubMed2006

[Indications and outcomes of epilepsy surgery in children].

INTRODUCTION: One in every four children who suffer epilepsy will continue to seize despite all the current arsenal of anticonvulsant medications. Epilepsy surgery can be an effective treatment for many cases of pharmaco-resistant epilepsy. AIM: To review some of the most recent data regarding indication and results for epilepsy surgery in children. DEVELOPMENT: New analysis of neurophysiological data such as magnetoencephalography, dipole analysis and high frequency oscillations, plus functional neuroimaging and higher resolution MRI, have improved the prompt referral of potential candidates for surgery. An adequate selection of the surgical candidates will be fundamental in obtaining positive outcomes. Children, just like adults, can achieve seizure freedom or more than 90% seizure reduction in 85% of the cases of temporal lobe resections. Extratemporal epilepsy surgery is more challenging, and presents frequently in epilepsy surgery centres specialized in pediatric care. CONCLUSION: It is not mandatory for a patient to have an structural lesion evident on MRI in order to be considered a candidate for epilepsy surgery. In many cases a partial reduction of seizure activity can significantly improve the patient's and family's quality of life, and can have a sinergistic effect with other therapies which were no effective before surgery.

Child↗
PubMed2006

Optical coherence tomography in multiple sclerosis.

We do not have currently satisfactory clinical and anatomical correlates to gauge disability in multiple sclerosis. Structural biomarkers (such as MRI) are hindered because they cannot precisely segregate demyelination from axonal elements of tissue injury within the CNS. Axonal degeneration in multiple sclerosis is related to irreversible disability, which suggests that the confirmation of neuroprotective strategies needs highly quantifiable measures of axon loss that can be correlated with reliable measures of physiological function. The coupling of quantifiable measures of visual function with ocular imaging techniques, such as optical coherence tomography, enables us to begin to understand how structural changes in the visual system influence function in patients with multiple sclerosis. In this review, we consider the usefulness of optical imaging of the retina as a biomarker for neurodegeneration in multiple-sclerosis.

Biomarkers↗
PubMed2002

The neuropathology of primary mood disorder.

The biological mechanisms proposed to underlie primary mood disorder do not usually include a neuropathological component. However, a significant MRI literature attests to structural abnormalities in regions and has encouraged neuropathological investigations from which candidate histological correlates have begun to emerge. In particular, there are several reports of cytoarchitectural alterations in anterior cingulate and prefrontal cortices, characterized by a decrease in the number or density of glia. Reductions in the size and density of some neuronal populations have also been described, accompanied by alterations in indices of synaptic terminals and dendrites. This form of pathology putatively reflects aberrant neurodevelopment or impaired cellular plasticity. A separate pathological process is suggested by the excess of subcortical focal lesions seen on MRI, especially in elderly patients; these probably reflect white matter damage of vascular origin. Both types of pathology have been observed, to a greater or lesser extent, in unipolar as well as bipolar mood disorders. None of the findings appear attributable to treatment with antidepressants, mood stabilizers or electroconvulsive therapy (ECT). However, all findings remain preliminary due to a lack of unequivocal replication and the failure to control fully for other potential confounders and co-morbid conditions. There are also basic questions to be answered concerning the clinical correlates, magnitude, progression and heterogeneity of the pathology. Nevertheless, it must now be considered likely that changes in brain structure, both macroscopic and microscopic, are a feature of primary mood disorder, a fact to be taken into account when interpreting functional imaging, neuropsychological and neurochemical data. The neuropathology is postulated to contribute to the pathophysiology and dysfunction of the neural circuits which regulate mood and its associated cognitions, behaviours and somatic symptoms.

Brain↗
PubMed1997

Brain perfusion SPECT abnormalities in neuronal ceroid lipofuscinoses.

Brain perfusion was studied with the Tc-99m-HMPAO SPECT method in 19 INCL patients, 21 JNCL patients and 5 patients with Jansky-Bielschowsky variant disease (JBVD). The typical SPECT findings at an early stage of INCL were bilateral anterior frontal, posterior temporoparietal and occipital hypoperfusion, whereas reduction in cerebellar perfusion appeared later. However, perfusion of basal ganglia and thalami, although atrophic on MRI, was usually well preserved up to the terminal stage. All JNCL patients except one had at least one hypoperfused area. Mild hypoperfusion was usually located in the parietal and occipital lobes and cerebellum, whereas more severe hypoperfusion was observed in the temporal lobes. In JNCL, SPECT revealed lesions not detected on CT. All JBVD patients had supra- and infratentorial hypoperfusion, which was usually bilateral. This study shows that although in NCLs brain hypoperfusion can appear prior to structural abnormalities seen on MRI or CT, such abnormalities are not always associated with significant hypoperfusion.

Adolescent↗
PubMed2000

Virtual endoscopy of the inner ear and the auditory canal.

To assess the role of virtual endoscopy (VE) in the examination of intracisternal structures and of the inner ear, we studied the anatomy of the labyrinth and internal auditory canal using the original CT slices and VE on the unaffected side in three female and three male patients, age range 3-46 years, with contralateral retrocochlear hearing loss. We also examined seven patients with different pathological findings. VE was performed using an advanced postprocessing program with high-resolution 3D data sets of CT (1-1.5 mm thickness, pitch 1.25) and MRI-CISS-3D (constructive interference in steady state) images of the basal cisterns (1.5 T, slice thickness 0.7-1 mm). VE provides an endoscopic-like view from a given point within the basal cisterns of vessels and nerves (on MRI) or of the structures of the inner ear (on CT). The complex anatomy and pathological changes in the inner ear can be faithfully shown. The main advantage is not basic diagnostic information but demonstration of topographically complex situations, such as the canalicular system of the inner ear, for discussion, preoperative planning and teaching.

Adolescent↗
PubMedDate not supplied

Comparative assessment of diseases of the orbit using computed tomography and magnetic resonance imaging.

Computed tomography (CT) and magnetic resonance imaging (MRI) are the modalities of choice in the assessment of inflammatory diseases, cysts, benign and malignant tumors found in the orbit. CT delineates, to greater advantage, bony structures and areas of calcification. MRI is superior to CT in visualization of the various soft tissue structures and in providing lesion characterization. The lesion location in the orbit is important: extraconal (frequently lymphomas), intraconal (most commonly cavernous hemangiomas and neurilemmomas), and optic nerve sheath (gliomas and meningiomas). The contours of the lesion are also significant: sharply delineated (benign), irregular, lobulated (lymphoma or lymphoid hyperplasia), or invasive (paranasal tumors). CT and MRI characteristics, in particular contrast enhancement, further contribute to the characterization of the various types of lesions within the orbit.

Humans↗
PubMed2005

Atlas-based automatic segmentation of MR images: validation study on the brainstem in radiotherapy context.

PURPOSE: Brain tumor radiotherapy requires the volume measurements and the localization of several individual brain structures. Any tool that can assist the physician to perform the delineation would then be of great help. Among segmentation methods, those that are atlas-based are appealing because they are able to segment several structures simultaneously, while preserving the anatomy topology. This study aims to evaluate such a method in a clinical context. METHODS AND MATERIALS: The brain atlas is made of two three-dimensional (3D) volumes: the first is an artificial 3D magnetic resonance imaging (MRI); the second consists of the segmented structures in this artificial MRI. The elastic registration of the artificial 3D MRI against a patient 3D MRI dataset yields an elastic transformation that can be applied to the labeled image. The elastic transformation is obtained by minimizing the sum of the square differences of the image intensities and derived from the optical flow principle. This automatic delineation (AD) enables the mapping of the segmented structures onto the patient MRI. Parameters of the AD have been optimized on a set of 20 patients. Results are obtained on a series of 6 patients' MRI. A comprehensive validation of the AD has been conducted on performance of atlas-based segmentation in a clinical context with volume, position, sensitivity, and specificity that are compared by a panel of seven experimented physicians for the brain tumor treatments. RESULTS: Expert interobserver volume variability ranged from 16.70 cm(3) to 41.26 cm(3). For patients, the ratio of minimal to maximal volume ranged from 48% to 70%. Median volume varied from 19.47 cm(3) to 27.66 cm(3) and volume of the brainstem calculated by AD varied from 17.75 cm(3) to 24.54 cm(3). Medians of experts ranged, respectively, for sensitivity and specificity, from 0.75 to 0.98 and from 0.85 to 0.99. Median of AD were, respectively, 0.77 and 0.97. Mean of experts ranged, respectively, from 0.78 to 0.97 and from 0.86 to 0.99. Mean of AD were, respectively, 0.76 and 0.97. CONCLUSIONS: Results demonstrate that the method is repeatable, provides a good trade-off between accuracy and robustness, and leads to reproducible segmentation and labeling. These results can be improved by enriching the atlas with the rough information of tumor or by using different laws of deformation for the different structures. Qualitative results also suggest that this method can be used for automatic segmentation of other organs such as neck, thorax, abdomen, pelvis, and limbs.

Algorithms↗
PubMed2002

Seizure-associated brain injury in term newborns with perinatal asphyxia.

BACKGROUND: There is controversy over whether seizures, the most common manifestation of neonatal brain injury, may themselves damage the developing brain. OBJECTIVE: To determine if neonatal seizures are independently associated with brain injury in newborns with perinatal asphyxia. METHODS: Ninety term neonates were studied with MRI and single-voxel (1)H-MRS on median day of life 6 (range 1 to 13 days). The severity of MR abnormality in the (1)H-MRS regions of interest was scored using a validated scale. Seizure severity was scored based on seizure frequency and duration, EEG findings, and anticonvulsant administration. Multivariable linear regression tested the independent association of seizure severity with impaired cerebral metabolism measured by lactate/choline and compromised neuronal integrity measured by N-acetylaspartate/choline in both regions. RESULTS: Clinical seizures occurred in 33 of 90 infants (37%). Seizure severity was associated with increased lactate/choline in both the intervascular boundary zone (p < 0.001) and the basal nuclei (p = 0.011) when controlling for potential confounders of MRI abnormalities and amount of resuscitation at birth. Each increase in seizure score was independently associated with a 21% increase in lactate/choline in the intervascular boundary zone (95% CI, 5.1-38.2%) and a 15% increase in the basal nuclei (95% CI, 0.1-31.7%). Seizure severity was independently associated with diminished N-acetylaspartate/choline in the intervascular boundary zone (p = 0.034). CONCLUSION: The severity of seizures in human newborns with perinatal asphyxia is independently associated with brain injury and is not limited to structural damage detectable by MRI.

Asphyxia Neonatorum↗
PubMed2002

Inguinal hernias: MRI and ultrasound.

This article presents an overview of the key anatomic structures of the groin region as seen on gross anatomy and the appearance of these structures on ultrasound and magnetic resonance imaging (MRI). An overview of the sonographic and MRI techniques used in preoperative diagnosis of inguinal hernias is provided, and their value is discussed. Finally, the role of ultrasound and MRI after surgical inguinal hernia repair is addressed.

Hernia, Inguinal↗
PubMed2004

Imaging of neurogenetic and neurometabolic disorders of childhood.

Magnetic resonance imaging (MRI) has emerged as a powerful tool in the study of normal and abnormal brain structure, function, and biochemistry. In particular, functional MRI has come into its own as a tool to study normal and abnormal brain functions such as learning, memory, and motor learning, as well as delineation of neurogenetic cognitive phenotypes. White matter microstructure can be studied using diffusion tensor imaging, which may allow abnormal white matter to be visualized prior to abnormalities on anatomic MRI. Magnetic resonance spectroscopy, a noninvasive method to study brain biochemistry, may allow for the delineation of regional metabolic changes as a result of disease progression and/or therapeutic intervention. With MRI techniques, one can investigate the relationship between structure, function, genes, and behavior. This report discusses the research applications of MRI to the study of neurogenetic disorders of childhood.

Child↗
PubMed2005

Hippocampal sclerosis in severe myoclonic epilepsy in infancy: a retrospective MRI study.

PURPOSE: Severe myoclonic epilepsy in infancy (SMEI; Dravet's syndrome) is a malignant epilepsy syndrome characterized by early prolonged febrile convulsions (PFCs) with secondary psychomotor delay and a variety of therapy-resistant seizures. Although the initial symptoms are repeated PFCs, the MRI performed at the onset of disease shows no hippocampal structural abnormalities. We aimed to assess clinical and serial MRI data of patients with SMEI with a special attention to the temporomedial structures. To our knowledge, this is the first systematic MRI study in this disease. METHODS: Clinical and MRI data of all SMEI patients treated in our hospitals between 1996 and 2004 were reviewed. RESULTS: Twenty-eight MRIs from 14 children (one to four images/patient) were included. Age at disease onset was between 3 and 9 months; age at initial MRI was 5 months to 13 years. Ten of 14 patients showed hippocampal sclerosis (HS) during the course of the disease (nine unilateral, one bilateral). Six of these 10 had a normal initial MRI. Age at the first verified HS was between 14 months and 13 years. Neither complex partial seizures nor anterior temporal irritative zone was recorded in these children. CONCLUSIONS: After initially normal structures, in most patients with SMEI, HS develops several months or years after the first PFC. These data support the hypothesis that PFC might be responsible for HS, but other factors and individual sensitivity should play a role in this process.

Adolescent↗
PubMedDate not supplied

A gadolinium(III) complex of a carboxylic-phosphorus acid derivative of diethylenetriamine covalently bound to inulin, a potential macromolecular MRI contrast agent.

A novel conjugate of a polysaccharide and a Gd(III) chelate with potential as contrast agent for magnetic resonance imaging (MRI) was synthesized. The structure of the chelate was derived from H5DTPA by replacing the central pendant arm by a phosphinic acid functional group, which was covalently bound to the polysaccharide inulin. On the average, each monosaccharide unit of the inulin was attached to approximately one (0.9) chelate moiety. The average molecular weight is 23110 and the average number of Gd3+ ions per molecule is 24. The ligand binds the Gd3+ ion in an octadentate fashion via three nitrogen atoms, four carboxylate oxygen atoms, and one P-O oxygen atom, and its first coordination sphere is completed by a water molecule. This compound shows promising properties for application as a contrast agent for MRI thanks to a favorable residence lifetime of this water molecule (170 ns at 298 K), a relatively long rotational correlation time (866 ps at 298 K), and the presence of two water molecules in the second coordination sphere of the Gd3+ ion. Furthermore, its stability toward transmetalation with Zn(II) is as high as that of the clinically used [Gd(DTPA)(H2O)]2-.

Contrast Media↗