Search results for " MRI."
showing 10 items of 211 documents
IMAGING OF VESTIBULAR SCHWANNOMA [Chapter 4]
2020
Lesions of the cerebellopontine angle and internal auditory canal are a frequent finding in neuroradiological examinations and their detection may represent a diagnostic challenge. Among these lesions, vestibular schwannomas and meningiomas are certainly the most frequent and account for up to 90% of all cerebellopontine angle tumours. The remaining ones are a group of lesions arising from the different structures found in these anatomical regions such as haemangiomas, lipomas, lymphomas, facial nerve tumours, and aneurysms. This chapter will introduce this topic focusing on a practical coverage of the typical and atypical neuroradiological signs that will drive towards the most correct dif…
Presacral Myelolipoma
2014
Many reports have described adrenal myelolipomas but there have been only a few reports of extra-adrenal myelolipomas. We describe a 74-year-old woman who came to our observa- tion for MRI of the lumbar spine for typical lumbar back pain. In addition to signs of mild scoliosis and spondylo disc arthrosis, MR imaging revealed a presacral mass showing a heterogeneously high signal in all pulse sequences and almost completely suppressed on inversion recovery sequences for fat tissue. CT imaging confirmed the fatty nature of the lesion and no signs of bone involvement. These findings were most consistent with a diagnosis of a rare presacral myelolipoma as confirmed at histopathologic analysis. …
Can histographic analysis of apparent diffusion coefficient help discriminate between benign and malignant nodes in head and neck squamous cell carci…
2011
Objective: To investigate histographic analysis of apparent diffusion coefficient (ADC) measurements as discriminators of benign from malignant lymph nodes in patients with head and neck (H&N) squamous cell carcinoma (SCC) Materials and Methods: Seventeen patients with H&N SCC staged for nodal disease using anatomical MRI, contrast enhanced CT and ultrasound ± fine needle aspiration gave informed consent for additional MR diffusion weighted imaging (DWI). Axial DWI was performed by short tau inversion recovery (STIR) echo planar imaging and trace weighted images obtained b 0, 50, 100, 300, 600 and 1000. Image analysis was conducted using Jim 5.0. Nodal disease and contralateral benign nodal…
The importance of level stratification for quantitative MR studies of lumbar intervertebral discs : a cross-sectional analysis in 101 healthy adults
2019
Purpose: To investigate whether quantitative T2-times depend on lumbar intervertebral disc (IVD) level. Methods: The lumbar spine (Th12/L1–L5/S1) of 101 participants (53.5% female, 30.0[± 3.6]years, 173.5[± 9.6]cm and 69.9[± 13.4]kg), without history of back pain, was examined on a 3T scanner with sagittal T2-mapping. All IVDs were stratified according to Pfirrmann grade and lumbar level, with mean T2-time determined for the entire IVD volume and in five subregions of interests. Results: Significant level-dependent T2-time differences were detected, both for the entire IVD volume and its subregions. For the entire IVD volume, Pfirrmann grade 2 IVDs displayed 9–18% higher T2-times in Th12/L1…
MRI of tarantulas: morphological and perfusion imaging.
2005
This paper describes a study performed to evaluate the feasibility of using a 1.5-T whole-body magnetic resonance imaging (MRI) equipment, in combination with pharmacokinetic modeling, to obtain in vivo information about the morphology and perfusion of tarantulas (Eurypelma californicum). MRI was performed on three tarantulas using spin-echo sequences for morphological imaging and a rapid spoiled gradient-echo sequence for dynamic imaging during and after contrast medium (CM; Gd-DTPA) injection. Signal enhancement in dynamic measurements was evaluated with a pharmacokinetic two-compartment model. Spin-echo images showed morphological structures well. Dynamic images were of sufficient qualit…
Abdominal splenosis and its differential diagnoses: What the radiologist needs to know
2021
Abstract Splenosis is a benign acquired condition characterized by the presence of heterotopic viable splenic tissue in other organs or within cavities such as peritoneum, retroperitoneum, or thorax after splenic trauma or surgery. Abdominal splenosis is often an incidental finding and computed tomography and magnetic resonance usually allow a confident diagnosis. The typical enhancement that parallels the spleen is a useful hallmark of splenosis. Splenic implants lack contrast uptake in the hepatobiliary phase and show high signal at high b-values on diffusion-weighted images. In some cases splenosis may mimic malignant and benign conditions in the peritoneum as well as in hollow and paren…
Resting state FMRI: A tool to investigate functional connectivity modulation induced by transcranial direct current stimulation of the motor network
2016
Introduction: Resting-state functional connectivity (fcMRI) represents a novel fMRI approach that allows detection of temporal correlations in spontaneous BOLD signal oscillations while subjects rest quietly in the scanner. Under resting conditions the brain is engaged in spontaneous activity that causes a low frequencies (<0.1 Hz) BOLD signal fluctuations. Functional connectivity (FC) can be defined as the synchrony of neural activity among spatially distant regions. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is known to modulate cortical activity and FC among brain regions, as measured by functional magnetic resonance imaging. This st…
The relationship between genetic risk variants with brain structure and function in bipolar disorder: A systematic review of genetic-neuroimaging stu…
2017
Genetic-neuroimaging paradigms could provide insights regarding the pathophysiology of bipolar disorder (BD). Nevertheless, findings have been inconsistent across studies. A systematic review of gene-imaging studies involving individuals with BD was conducted across electronic major databases from inception until January 9th, 2017. Forty-four studies met eligibility criteria (N = 2122 BD participants). Twenty-six gene variants were investigated across candidate gene studies and 4 studies used a genome-wide association approach. Replicated evidence (i.e. in >2 studies) suggests that individuals with BD carrying the BDNF Val66Met risk allele could have reduced hippocampal volumes compared …
CNN-Based Prostate Zonal Segmentation on T2-Weighted MR Images: A Cross-Dataset Study
2020
Prostate cancer is the most common cancer among US men. However, prostate imaging is still challenging despite the advances in multi-parametric magnetic resonance imaging (MRI), which provides both morphologic and functional information pertaining to the pathological regions. Along with whole prostate gland segmentation, distinguishing between the central gland (CG) and peripheral zone (PZ) can guide toward differential diagnosis, since the frequency and severity of tumors differ in these regions; however, their boundary is often weak and fuzzy. This work presents a preliminary study on deep learning to automatically delineate the CG and PZ, aiming at evaluating the generalization ability o…
Water capillary absorption in porous media in different wettability conditions studied by Quantitative MRI and X-ray CT
2007
X-ray computed tomography (CT) and magnetic resonance imaging (MRI) have been successfully applied to study both the capillary properties of several samples of Lecce stone and the performances of treatments used for protection and conservation of historical stone artifacts. The presence of water inside the sample may be visualized by both MRI and X-ray CT. For the treated samples, the different dynamics of water absorption gives indirectly the efficacy of the polymer in the rock.