Search results for "MRI."
showing 10 items of 591 documents
Imaging of Substantia Nigra in Parkinson's Disease: A Narrative Review.
2021
Parkinson’s disease (PD) is a progressive neurodegenerative disorder, characterized by motor and non-motor symptoms due to the degeneration of the pars compacta of the substantia nigra (SNc) with dopaminergic denervation of the striatum. Although the diagnosis of PD is principally based on a clinical assessment, great efforts have been expended over the past two decades to evaluate reliable biomarkers for PD. Among these biomarkers, magnetic resonance imaging (MRI)-based biomarkers may play a key role. Conventional MRI sequences are considered by many in the field to have low sensitivity, while advanced pulse sequences and ultra-high-field MRI techniques have brought many advantages, partic…
Widespread white matter microstructural abnormalities in bipolar disorder: evidence from mega- and meta-analyses across 3033 individuals
2019
Fronto-limbic white matter (WM) abnormalities are assumed to lie at the heart of the pathophysiology of bipolar disorder (BD);\ud however, diffusion tensor imaging (DTI) studies have reported heterogeneous results and it is not clear how the clinical\ud heterogeneity is related to the observed differences. This study aimed to identify WM abnormalities that differentiate patients with\ud BD from healthy controls (HC) in the largest DTI dataset of patients with BD to date, collected via the ENIGMA network. We gathered\ud individual tensor-derived regional metrics from 26 cohorts leading to a sample size of N = 3033 (1482 BD and 1551 HC). Mean\ud fractional anisotropy (FA) from 43 regions of i…
Radiolabeled DNase, a potential indicator for noninvasive detection of tissue damage
1983
Pancreatic DNase I was labeled with 131I or fluorescamine and injected IV into NMRI mice bearing a sarcoma 180. Of the injected tracer, 1.5%-2% was found to accumulate per g tumor. In sections of tumor tissue DNase was localized in damaged cells in solid and necrotic tumor regions. This binding is most probably due to specific interaction of DNase with actin, an ubiquitous cytoskeletal protein. Two-component blood clearance with a rapid first component (two-thirds of applied radioactivity) was observed. The labeled tumor could easily be visualized by gamma camera imaging. The findings suggest DNase to be a potent radiopharmaceutical for imaging damaged tissue, occurring in malignant tumors …
T2 mapping of the peritumoral infiltration zone of glioblastoma and anaplastic astrocytoma.
2021
Purpose To characterise peritumoral zones in glioblastoma and anaplastic astrocytoma evaluating T2 values using T2 mapping sequences. Materials and methods In this study, 41 patients with histopathologically confirmed World Health Organization high grade gliomas and preoperative magnetic resonance imaging examinations were retrospectively identified and enrolled. High grade gliomas were differentiated: (a) by grade, glioblastoma versus anaplastic astrocytoma; and (b) by isocitrate dehydrogenase mutational state, mutated versus wildtype. T2 map relaxation times were assessed from the tumour centre to peritumoral zones by means of a region of interest and calculated pixelwise by using a fit m…
Dysembryoplastic Neuroepithelial Tumor of the Brainstem
2007
Dysembryoplastic neuroepithelial tumor (DNT) is a clinically benign stable lesion, most frequently located in the temporal and frontal lobes, often responsible for epilepsy in young adults. We describe an unusual case of DNT in the brainstem of a 45-year-old woman. Brain MRI showed a multicystic-like lesion localized in the left inferior pons, involving the ipsilateral cerebellar peduncle and partially dislocating the fourth ventricle. The specific pattern of MRI and CT appearance of DNT and its benign course (our patient is clinically stable with unchanged MRI images at two year follow-up) may help differentiate this tumor from other lesions, i.e. ganglioglio-mas and glioneural malformati…
Rectal cancer: Dynamic contrast-enhanced MRI correlates with lymph node status and epidermal growth factor receptor expression
2013
Purpose To evaluate correlations between dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and clinicopathologic data as well as immunostaining of the markers of angiogenesis epidermal growth factor receptor (EGFR) and CXC-motif chemokine receptor 4 (CXCR4) in patients with rectal cancer. Materials and Methods Presurgical DCE-MRI was performed in 41 patients according to a standardized protocol. Two quantitative parameters (k21, A) were derived from a pharmacokinetic two-compartment model, and one semiquantitative parameter (TTP) was assessed. Standardized surgery and histopathologic examinations were performed in all patients. Immunostaining for EGFR and CXCR4 was performed an…
Variations in the size of focal nodular hyperplasia on magnetic resonance imaging
2013
Abstract Objective To evaluate the changes in the size of focal nodular hyperplasia (FNH) during long-term magnetic resonance imaging (MRI) follow-up. Material and methods We reviewed 44 FNHs in 30 patients studied with MRI with at least two MRI studies at least 12 months apart. We measured the largest diameter of the lesion (in mm) in contrast-enhanced axial images and calculated the percentage of variation as the difference between the maximum diameter in the follow-up and the maximum diameter in the initial study. We defined significant variation in size as variation greater than 20%. We also analyzed predisposing hormonal factors. Results The mean interval between the two imaging studie…
Angiogenesis of cancer of the cervix. Contrast-enhanced dynamic MRT, histological quantification of capillary density and lymph system infiltration
1998
Purpose: It was the aim of this project to examine (i) the relationships between contrast-enhanced dynamic MR imaging derived characteristics and histologic microvessel density counts – a recognized surrogate of tumor angiogenesis – from tumors in patients with primary or recurrent cancer of the uterine cervix, and (ii) to correlate these parameters with lymphatic involvement (i. e. lymphatic channels) to assess tumorbiological aggressiveness in terms of lymphatic spread. Materials and methods: Pharmacokinetic MR imaging parameters (amplitude A, exchange rate constant k 21) were derived from contrast-enhanced dynamic MR imaging in thirty-three patients with biopsy proven cancer of the uteri…
5-6 gadīgu bērnu problēmrisināšanas prasmes sekmēšana matemātikā
2020
Lauras Vanagas bakalaura darbs pedagoģijā, pirmsskolas un sākumskolas skolotāju programmā, “5- 6 gadīgu bērnu problēmrisināšanas prasmes sekmēšana matemātikā”, izstrādāts Latvijas Univeristātes Pedagoģijas, psiholoģijas un mākslas fakultātē Alūksnes filiālē, Dr.paed profesores Dagnijas Vigules vadībā. Bakalaura darba mērķis ir- teorētiski un empīriski pētīt 5- 6 gadīgu bērnu problēmrisināšanas prasmes sekmēšanu matemātikā. Pētījuma hipotēze- 5-6 gadīgu bērnu problēmrisināšanas prasmes matemātikā tiek sekmētas, ja pedagogs zina, kā organizēt mācību procesu un bērns iesaistās problēmsituācijas risināšanā, kas atbilst viņa interesēm un vajadzībām Pētījuma teorētiskajā daļā aprakstīts pirmsskol…
Problēmrisināšanas metodes izmantošana fizikas un dabaszinību apguvē vidusskolā
2015
Problēmrisināšanas metodes izmantošana fizikas un dabaszinību apguvē vidusskolā. Marika Melne, darba vadītāja Dr. phys., Inese Dudareva, bakalaura darbs satur 48 lappuses, 5 nodaļas un 18 apakšnodaļas, 21 attēlu, 1 tabulu, 4 pielikumus 16 lappušu apjomā, izmantoti 15 literatūras avoti. Latviešu valodā. Darbā dots problēmrisināšanas vispārīgs apraksts, problēmrisināšanas kā metodes izmantošanas iespējas fizikas un dabaszinību stundās mācību satura apguvē. Izveidoti metodiskie materiāli latviešu valodā 3 tēmu apguvei fizikā un dabaszinībās, izmantojot problēmrisināšanas metodi. Noskaidrota skolēnu attieksme pret šādas metodes izmantošanu mācību satura apguvē un metodes ietekme uz skolēnu mācī…