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PubMed1992

Spatial integration of multimodal brain images in cerebral infarction.

Different structural as well as functional imaging techniques are becoming increasingly important in the investigation of patients suffering from an ischemic stroke. Available imaging procedures usually provide complementary data, but the images can not easily be compared due to differences in patient positioning, angulation, and slice thickness. We studied the value of spatial integration of images from different modalities in a patient with an ischemic stroke and used skin markers to integrate the obtained information. Computed tomography (CT), magnetic resonance imaging (MRI), 99mTcHMPAO-single photon emission computed tomography (SPECT) and magnetic resonance spectroscopic imaging (MRSI) were performed in a patient, presenting with a right sided hemiparesis caused by an ischemic stroke. Combination of MRI with CT demonstrated that the infarction visible on CT and MRI corresponded in size and volume. Furthermore, structural and functional images could readily be integrated, thus allowing us to obtain accurate information in this stroke patient. Different imaging modalities provide complementary information in the acute phase of cerebral infarction and multimodality matching can be of great value for improvement of our understanding of the pathophysiology and course of ischemic stroke.

Brain↗
PubMed2004

A magnetic resonance imaging study of cortical thickness in animal phobia.

BACKGROUND: Despite the high prevalence of specific phobia (SP), its neural substrates remain undetermined. Although an initial series of functional neuroimaging studies have implicated paralimbic and sensory cortical regions in the pathophysiology of SP, to date contemporary morphometric neuroimaging methods have not been applied to test specific hypotheses regarding structural abnormalities. METHODS: Morphometric magnetic resonance imaging (MRI) methods were used to measure regional cortical thickness in 10 subjects with SP (animal type) and 20 healthy comparison (HC) subjects. RESULTS: Consistent with a priori hypotheses, between-group differences in cortical thickness were found within paralimbic and sensory cortical regions. Specifically, in comparison with the HC group, the SP group exhibited increased cortical thickness in bilateral insular, bilateral pregenual anterior cingulate, and bilateral posterior cingulate cortex as well as left visual cortical regions. CONCLUSIONS: Taken together, these structural findings parallel results from initial functional imaging studies that implicate paralimbic and sensory cortical regions in the mediating anatomy of SP symptoms. Further research will be necessary to replicate these findings and to determine their specificity as well as their pathophysiologic significance.

Adult↗
PubMed2002

Effect of jet fuels on the skin morphology and irritation in hairless rats.

Jet A and JP-8 are the major jet fuels used in civilian and military (US Air Force) flights, respectively. JP-8+100 is a new jet fuel recently introduced by US Air Force in some of its locations. The purpose of this study was to investigate the effects of dermal exposure of jet fuels (Jet A, JP-8, and JP-8+100) on the skin morphology, barrier function, moisture content, blood flow, and skin irritation (erythema and edema) in hairless rats. Jet fuels were applied by both occlusive and unocclusive methods. The skin of treated and control (untreated) sites were excised and analyzed by magnetic resonance imaging (MRI) (500 MHz, 11.7 Tesla). Unocclusive application of JP-8, Jet A, and JP-8+100 increased the transepidermal water loss (TEWL) gradually and the values at 120 h were significantly greater than the baseline value (P<0.05). Both occlusive and unocclusive application of jet fuels decreased the skin moisture content significantly (P<0.05). Unocclusive application of JP-8, Jet A, and JP-8+100 increased the skin blood flow, though the values returned to the baseline levels within 24 h. Occlusive application of jet fuels (8 h/day for 2 days) caused a substantial increase in the skin blood flow and the values at 48 h were about 6-fold greater than the baseline value. Occlusive application of jet fuels caused a moderate to severe erythema and a moderate edema. MRI was used to obtain proton images and water self-diffusion maps of hairless rat skin exposed to jet fuel. Exposure to JP-8 showed the largest difference from the control with regards to visual observations of the stratum corneum and hair follicles, while JP-8+100 appeared to affect the hair follicle region. The results of the present study demonstrate that exposure to jet fuels can disrupt the skin barrier function, cause skin irritation, and alter the skin structure (stratum corneum and viable epidermis) and MRI can be used as a tool to investigate the alterations in the skin morphology after exposure to toxic chemicals.

Animals↗
PubMed2001

Isolated cervical juvenile xanthogranuloma in childhood.

STUDY DESIGN: This is a report of an exceptional case of isolated cervical juvenile xanthogranuloma in a child. OBJECTIVES: This case report draws attention to the fact that isolated xanthogranuloma of the central nervous system should be considered among possible diagnosis of subdural extramedullary spinal masses in children and young adults. SUMMARY AND BACKGROUND DATA: Isolated juvenile xanthogranuloma of the central nervous system is extremely rare. When located in the spinal canal it behaves like any extramedullary mass-occupying lesion. MRI depicts the tumor's association with adjacent structures. In cases in which a subtotal surgical removal was possible, radiotherapy has been indicated. METHODS: A three-year-old girl presented severe pain in the right shoulder and spastic tetraparesis. The MRI showed an intradural extramedullary mass homogeneously enhancing after DTPA-gadolinium infusion. Complete surgical removal of the tumor was performed through open-door laminoplasty. RESULTS: The child was pain free immediately after the surgical removal of the tumor. A gradual complete recovery of the neurologic deficits followed. Open-door laminoplasty provided sufficient operative space, and it minimized the impact on the growing spinal column. CONCLUSIONS: Isolated juvenile xanthogranuloma does not show any predilections of localization inside the central nervous system. Both intracranial and spinal juvenile xanthogranulomas appear isointense in MRI and enhance homogeneously with gadolinium. Whenever possible, total surgical removal alone seems to be curative. Otherwise, a subtotal removal of the tumor might be followed by radiotherapy. Immunohistochemical tests ensure the diagnosis.

Cervical Vertebrae↗
PubMed1993

Magnetic resonance imaging in patients with concurrent Tourette's disorder and Asperger's syndrome.

OBJECTIVE: The purpose of the study was to examine behavioral/cognitive and neuroradiological features of patients with concurrent Tourette's disorder (TD) and Asperger's syndrome (AS). METHODS: The authors studied the occurrence of structural brain abnormalities using magnetic resonance imaging (MRI) in seven males with concurrent TD and AS, and in nine age-matched males, who had TD but did not have AS. Both groups were tested with an extensive battery of neurological and psychiatric rating scales and cognitive tests. RESULTS: Five of the seven patients with TD and AS had developmental brain anomalies. In contrast, normal MRI scans were found in all but one TD patient without AS. Both groups were not significantly different in the severity of motor and phonic tics, obsessionality, depression and anxiety, or in measures of general intelligence, memory, and language function; but patients with TD and AS had a history of more psychiatric hospitalizations, poor academic achievement, more neurological soft signs and appeared more impaired on complex problem-solving and spatial tests than did TD patients without AS. CONCLUSION: These findings suggest that structural cortical and subcortical abnormalities are more common among individuals with concurrent TD and AS than among sex- and age-matched TD patients without AS. Dysfunction of frontal-subcortical systems may play a role in the pathophysiology of concurrent TD and AS.

Adolescent↗
PubMed1997

[Heart tumors].

Tumors of the heart are very rare. Due to the nonspecific clinical presentation the diagnosis is usually made by radiological procedures. Cardiac myxomas and thrombi are the most common cardiac masses. Two-dimensional echocardiography is the method of choice for the initial evaluation of cardiac tumors, because it permits the accurate determination of the tumor's size, localization, point of attachment, mobility and haemodynamic significance. Inadequate or nondiagnostic ultrasound examination and the need for preoperative assessment are indications for further examinations, such as magnetic resonance imaging (MRI) and computed tomography. Both these methods are helpful in the assessment of paracardiac structures and of the tumor invasion into great vessels and the mediastinum. MRI allows a limited degree of assessment of whether or not the tumor is malignant by soft tissue characterization. In the case of resectable, symptomatic, cardiac tumors surgical excision should be performed.

Diagnostic Imaging↗
PubMed2006

Noninvasive assessment of bone microarchitecture by MRI.

In determining fracture risk, it has become apparent that bone mineral density accounts for only a portion of bone strength, with the remainder being determined by the material and structural properties of the bone tissue. Over the past 15 years, high-resolution MRI has provided a window into the structural nature of bone disease. Cross-sectional studies imaging the trabecular bone in patients with conditions ranging from postmenopausal osteoporosis to organ transplantation to renal osteodystrophy have all demonstrated a correlation of microarchitecture with fracture burden and have done so at a variety of anatomic sites. Recently, the utility of longitudinal studies for monitoring treatment in vivo has been demonstrated. This technique is noninvasive, involving no contrast or ionizing radiation, and provides useful clinical information independent of bone mineral density, thereby allowing for better classification of those at high risk for fracture.

Animals↗
PubMed1989

Magnetic resonance imaging and computed tomography in long-term-functioning duct-occluded pancreas allotransplants.

Duct-occluded segmental-pancreas transplants develop progressive fibrotic atrophy, even though endocrine function seems to be unaffected. To determine end-stage size of the graft and to evaluate magnetic resonance imaging (MRI) and computed tomography (CT), these imaging techniques were applied in eight patients with well-functioning intraperitoneal prolamine-injected segmental-pancreas transplants for 79, 48, 35, 20, 19, 19, 18, and 10 mo. MRI was performed on a 1.5 Tesla system (Philips Gyroscan S15). T1- and T2-weighted images were acquired. CT (Siemens Somatom 2) was done before and after intravenous contrast agent. The graft was visualized in seven of eight patients with both techniques. Visualization with MRI (vs. CT) was considered excellent in 2 (vs. 1), good in 3 (vs. 6), and poor in 2 (vs. 0). The three grafts with function longer than 2 yr measured 3-4 cm in length; the remaining grafts measured 3-6 cm. Because of a marked decrease in size the transplants were no longer localized in Douglas' pouch but adjacent to or on top of the uterus or bladder, the position depending on the volume of these organs. The allografts exhibited an inhomogeneous structure with casual cystic degeneration visible with MRI due to a high signal intensity on T2-weighted images. This study suggests that shrinkage of the duct-occluded pancreatic segment due to exocrine atrophy may be terminated after approximately 2 yr. It is concluded that thereafter an overshooting fibrosis causing late endocrine graft failure may not be anticipated.

Adult↗
PubMedDate not supplied

[Wilm's tumor. Diagnostic capacities of magnetic resonance imaging. MRI-pathomorphological comparison].

The accuracy of magnetic resonance imaging (MRI) in the diagnosis of Wilms' tumor (WT) and in the evaluation of preoperative chemotherapy (PCH) efficiency was investigated and compared with histopathological data of 56 children and infants with proven retroperitoneum neoplasma (WT--49, neuroblastoma--6, congenital mesoblastic nephroma--1). The author described the WT MRI-semiotics in general and in particular for its changes during the preoperative chemotherapy. The formula for calculation of tumor reduction index is suggested. The MRI sensitivity (100%), specificity (77.8%) and accuracy (91.1%) are detected. The high positive correlation level between the MRI and pathologic findings, concerning WT dimensions, pseudocapsule presence and safety, tumor structure secondary alterations and tumor spreading was found. At the same time, the specific MRI criteria for the different histological types of WT were not found. MRI is confirmed to be an accurate tool for diagnostic monitoring of patients with WT and other retroperitoneum neoplasms.

Child↗
PubMed2004

Automatic segmentation of thalamus from brain MRI integrating fuzzy clustering and dynamic contours.

Thalamus is an important neuro-anatomic structure in the brain. In this paper, an automated method is presented to segment thalamus from magnetic resonance images (MRI). The method is based on a discrete dynamic contour model that consists of vertices and edges connecting adjacent vertices. The model starts from an initial contour and deforms by external and internal forces. Internal forces are calculated from local geometry of the model and external forces are estimated from desired image features such as edges. However, thalamus has low contrast and discontinues edges on MRI, making external force estimation a challenge. The problem is solved using a new algorithm based on fuzzy C-means (FCM) unsupervised clustering, Prewitt edge-finding filter, and morphological operators. In addition, manual definition of the initial contour for the model makes the final segmentation operator-dependent. To eliminate this dependency, new methods are developed for generating the initial contour automatically. The proposed approaches are evaluated and validated by comparing automatic and radiologist's segmentation results and illustrating their agreement.

Algorithms↗
PubMed2005

Material properties estimation of layered soft tissue based on MR observation and iterative FE simulation.

In order to calculate deformation of soft tissue under arbitrary loading conditions, we have to take both non-linear material characteristics and subcutaneous structures into considerations. The estimation method of material properties presented in this paper accounts for these issues. It employs a compression test inside MRI in order to visualize deformation of hypodermic layered structure of living tissue, and an FE model of the compressed tissue in which non-linear material model is assigned. The FE analysis is iterated with updated material constant until the difference between the displacement field observed from MR images and calculated by FEM is minimized. The presented method has been applied to a 3-layered silicon rubber phantom. The results show the excellent performance of our method. The accuracy of the estimation is better than 15%, and the reproducibility of the deformation is better than 0.4 mm even for an FE analysis with different boundary condition.

Compressive Strength↗
PubMed2002

Spatial normalization and averaging of diffusion tensor MRI data sets.

Diffusion tensor magnetic resonance imaging (DT-MRI) is unique in providing information about both the structural integrity and the orientation of white matter fibers in vivo and, through "tractography", revealing the trajectories of white matter tracts. DT-MRI is therefore a promising technique for detecting differences in white matter architecture between different subject populations. However, while studies involving analyses of group averages of scalar quantities derived from DT-MRI data have been performed, as yet there have been no similar studies involving the whole tensor. Here we present the first step towards realizing such a study, i.e., the spatial normalization of whole tensor data sets. The approach is illustrated by spatial normalization of 10 DT-MRI data sets to a standard anatomical template. Both qualitative and quantitative approaches are described for assessing the results of spatial normalization. Techniques are then described for combining the spatially normalized data sets according to three definitions of average, i.e., the mean, median, and mode of a distribution of tensors. The current absence of, and hence need for, appropriate statistical tests for comparison of results derived from group-averaged DT-MRI data sets is then discussed. Finally, the feasibility of performing tractography on the group-averaged DT-MRI data set is investigated and the possibility and implications of generating a generic map of brain connectivity from a group of subjects is considered.

Adult↗
PubMed2004

Cerebral cortex three-dimensional profiling in human fetuses by magnetic resonance imaging.

Seven human fetuses of crown/rump length corresponding to gestational ages ranging from the 12th to the 16th week were studied using a paradigm based on three-dimensional reconstruction of the brain obtained by magnetic resonance imaging (MRI). The aim of the study was to evaluate brain morphology in situ and to describe developmental dynamics during an important period of fetal morphogenesis. Three-dimensional MRI showed the increasing degree of maturation of the brains; fronto-occipital distance, bitemporal distance and occipital angle were examined in all the fetuses. The data were interpreted by correlation with the internal structure as visualized using high-spatial-resolution MRI, acquired using a 4.7-T field intensity magnet with a gradient power of 20 G cm(-1). The spatial resolution was sufficient for a detailed detection of five layers, and the contrast was optimized using sequences with different degrees of T1 and T2 weighting. Using the latter, it was possible to visualize the subplate and marginal zones. The cortical thickness was mapped on to the hemispheric surface, describing the thickness gradient from the insular cortex to the periphery of the hemispheres. The study demonstrates the utility of MRI for studying brain development. The method provides a quantitative profiling of the brain, which allows the calculation of important morphological parameters, and it provides informative regarding transient features of the developing brain.

Cerebral Cortex↗
PubMed2004

High-resolution MRI of the anatomy important in total mesorectal excision of the rectum.

OBJECTIVE: The surgical removal of a rectal carcinoma and the adjacent lymph nodes in an en bloc package lessens the risk of local recurrence due to residual tumor. Heightened awareness of good surgical techniques has created much interest in the anatomy involved in total mesorectal excision surgery, with particular focus on the fascial planes and nerve plexuses and their relationship to the surgical planes of excision. Clear preoperative depiction of these relationships is of value in determining tumor resectability. The aim of this study was to describe the radiologic appearance of these anatomic structures. SUBJECTS AND METHODS. High-spatial-resolution T2-weighted MRI was performed using a 1.5-T system in cadaveric sections and in patients before they underwent total mesorectal excision surgery. Anatomic dissections of sagitally sectioned hemipelves were compared with MRIs obtained in vivo to establish criteria for visualization of the structures relevant to anterior resection of the rectum. RESULTS: High-spatial-resolution MRI depicted a number of structures of importance in total mesorectal excision surgery. The mesorectal fascia, which forms the boundary of the surgical excision plane in total mesorectal excision, was identified, and the presacral fascia, peritoneal reflection, and Denonvilliers' fascia were also shown. Structures 1-2 mm in diameter were visualized because the contrast resolution afforded by T2-weighted fast spin-echo imaging permitted depiction of the inferior hypogastric nerve plexus and the fascial planes within the posterior pelvis. CONCLUSION: Anatomic landmarks important to the performance of rectal cancer surgery, in particular the mesorectal fascia, may be defined on MRI and are of potential importance in the staging of tumors, assessing resectability, planning surgery, and selecting patients for preoperative neoadjuvant therapy.

Aged↗
PubMed1997

[Image fusion of different tomographic methods (PET/CT/MRI) effectively contribute to therapy planning].

Image fusion (and image registration) is a fundamental topic of three-dimensional (3D) medical image processing. The need to register different imaging modalities arises for several reasons: some anatomical details, especially soft tissues, are more easily seen in MRI than CT images, but the bony structures are better visualised by CT. The visualisation of any morphological volume with a functional data set which may come from SPECT or PET is a very important method both for research purposes and for routine diagnostics. Our developed programs allowing us to solve image fusion tasks also contained some free available softwares. These packages helped us to start additional software development for more advanced applications having elaborated this way the informatical background of multimodality image processing. This paper presents three oncological applications of the image fusion: PET-CT-MRI registration for 3D radiotherapy planning, PET-MRI registration in planning surgery and metastasis localization. All these registration processes were solved by the landmark-matching registration method.

Decision Making↗
PubMed2004

Progression of brain damage after status epilepticus and its association with epileptogenesis: a quantitative MRI study in a rat model of temporal lobe epilepsy.

PURPOSE: This study examined the hypothesis that neurodegeneration continues after status epilepticus (SE) ends and that the severity of damage at the early phase of the epileptogenic process predicts the outcome of epilepsy in a long-term follow-up. METHODS: SE was induced in rats by electrical stimulation of the amygdala, and the progression of structural alterations was monitored with multiparametric magnetic resonance imaging (MRI). Absolute T2, T1rho, and diffusion (Dav) images were acquired from amygdala, piriform cortex, thalamus, and hippocampus for < or = 4.5 months after SE. Frequency and type of spontaneous seizures were monitored with video-electroencephalography recordings. Histologic damage was assessed from Nissl, Timm, and Fluoro-Jade B preparations at 8 months. RESULTS: At the acute phase (2 days after SE induction), quantitative MRI revealed increased T2, T1rho, and Dav values in the primary focal area (amygdala), reflecting disturbed water homeostasis and possible early structural damage. Pathologic T2 and T1rho were observed in mono- or polysynaptically connected regions, including the piriform cortex, midline thalamus, and hippocampus. The majority of acute MRI abnormalities were reversed by 9 days after SE. In later time points (> 20 days after induction), both the T1rho and diffusion MRI revealed secondarily affected areas, most predominantly in the amygdala and hippocampus. At this time, animals began to have spontaneous seizures. The initial pathology revealed by MRI had a low predictive value for the subsequent severity of epilepsy and tissue damage. CONCLUSIONS: The results demonstrate progressive neurodegeneration after SE in the amygdala and the hippocampus and stress the need for continued administration of neuroprotectants in the treatment of SE even after electrographic seizure activity has ceased.

Amygdala↗
PubMed2006

Magnetic resonance imaging of the canine shoulder: an anatomic study.

OBJECTIVES: To describe the normal anatomy of the soft tissue stabilizing components of the canine shoulder identified by magnetic resonance imaging (MRI) and to evaluate specific acquisition sequences and planes for observing structures of diagnostic interest. STUDY DESIGN: Descriptive study. ANIMAL: Canine cadavers (n=3). METHODS: T1-weighted, proton density fat saturation (PD), and T2(*)-weighted gradient echo (GE) MRI sequences were obtained in the sagittal, transverse, and dorsal planes of the left shoulder of 3 canine cadavers. After imaging, each shoulder was embedded and thin sectioned. The corresponding right shoulder was frozen and thick sectioned. The anatomic structures on the histologic and frozen thick sections were visually correlated with the MR images. RESULTS: The sagittal plane provided a longitudinal view of the bicep, infraspinatus, and supraspinatus tendons. The biceps, supraspinatus, infraspinatus, and subscapularis tendons, and the medial and lateral glenohumeral ligaments were identified in the transverse and dorsal planes. The dorsal plane allowed for the bicep tendon to be evaluated transversely as it passed over the humeral head. The GE sequence was more useful in identifying tendons and ligaments. The PD sequence was more helpful in identifying fluid accumulations in the joint and around tendons. CONCLUSIONS: The tendinous and ligamentous structures that stabilize the canine shoulder joint can be readily identified with MRI. CLINICAL RELEVANCE: MRI has the potential to be a useful tool in the diagnosis of canine soft tissue shoulder injuries.

Animals↗
PubMed1990

Magnetic resonance imaging in aggressive fibromatosis.

The magnetic resonance imaging (MRI) features of aggressive fibromatosis in 11 patients (five with recurrent tumour) and its contribution to patient management are described. Tumour signal intensity ranged from being low to isointense with respect to muscle on T1-weighted images while being predominantly of heterogenous increased signal intensity on T2-weighted images. A post-contrast (Gd-DTPA) study demonstrating diffuse tumour enhancement was of value in assessing tumour extent in two patients. CT in six patients and angiography in two patients provided no additional information while tumour relationship to neurovascular structures and extent was better appreciated on MRI. MRI was accurate in predicting resectability in all six patients who had surgery.

Adolescent↗