Search results for "MR"

A Semi-automatic Multi-seed Region-Growing Approach for Uterine Fibroids Segmentation in MRgFUS Treatment

2013

Fibroids are benign tumors growing in the uterus. Most of fibroids do not require treatment unless they are causing symptoms. Traditional surgery treatments, like myomectomy and hysterectomy, are very invasive therapeutic approaches which not always preserves reproductive potential of the woman. MRgFUS, performed with Insightec ExAblate 2100 equipment, is a new and noninvasive technique for uterine fibroids treatment, not requiring hospitalization and recovery time for patients. An initial assessment of MRgFUS treatment is made by computing the ablated volume of uterine fibroid. In this paper a semi-automatic approach, based on region-growing segmentation technique, is proposed. The impleme…

Multiparametric 18F-FDG PET-MRI of the breast: are there differences in imaging biomarkers of contralateral healthy tissue between patients with and …

2019

The rationale was to assess whether there are differences in multiparametric 18F-FDG PET/MRI biomarkers of contralateral healthy breast tissue in patients with benign and malignant breast tumors. Methods: In this institutional review board-approved prospective single-institution study, 141 women with imaging abnormalities on mammography or sonography (BI-RADS 4/5) underwent combined 18F-FDG PET/MRI of the breast at 3T with dynamic contrast-enhanced MRI, diffusion-weighted imaging, and the radiotracer 18F-FDG. In all patients, the following imaging biomarkers were recorded for the contralateral (tumor-free) breast: breast parenchymal uptake (BPU) (from 18F-FDG PET), mean apparent diffusion c…

Information transfer and information modification to identify the structure of cardiovascular and cardiorespiratory networks

2017

To fully elucidate the complex physiological mechanisms underlying the short-term autonomic regulation of heart period (H), systolic and diastolic arterial pressure (S, D) and respiratory (R) variability, the joint dynamics of these variables need to be explored using multivariate time series analysis. This study proposes the utilization of information-theoretic measures to measure causal interactions between nodes of the cardiovascular/cardiorespiratory network and to assess the nature (synergistic or redundant) of these directed interactions. Indexes of information transfer and information modification are extracted from the H, S, D and R series measured from healthy subjects in a resting…

Magnetic Resonance Imaging of Liver Transplant

2021

MR imaging increasingly has been adopted for follow-up imaging post-liver transplantation and for diagnosis of its complications. These include vascular and biliary complications as well as post-transplant malignancies. Interpretation of postoperative MR imaging should take into account the surgical technique and expected post-transplant changes. Contrast-enhanced MR imaging has high sensitivity for identification of vascular complications. MR cholangiopancreatography on the other hand is the most accurate noninvasive method for evaluation of biliary complications.

Clinical support in radiation therapy scenarios: MR brain tumor segmentation using an unsupervised fuzzy C-Means clustering technique

2016

Measurable Residual Disease (MRD) Monitoring in Acute Myeloid Leukemia (AML) with t(8;21)(q22;q22.1) RUNX1-RUNX1T1 Identifies Patients at High Risk o…

2019

Background: Acute myeloid leukemia (AML) with t(8;21)(q22;q22.1) resulting in the RUNX1-RUNX1T1 gene fusion is considered favorable in the 2017 genetic risk stratification by the European LeukemiaNet (ELN). After intensive chemotherapy most patients (pts) achieve complete remission (CR), but relapse occurs in about 50% and is associated with poor prognosis. In this AML subgroup monitoring of measurable residual disease (MRD) has been shown to identify pts at higher risk of relapse. Aims: To assess the prognostic impact of MRD monitoring in bone marrow (BM) and peripheral blood (PB) in a large cohort of 155 clinically well-annotated t(8;21)-AML pts enrolled in one of six AMLSG treatment tria…

Undetected Malignancies of the Breast: Dynamic Contrast-enhanced MR Imaging at 1.0 T

2002

To assess the prevalence and characteristics of malignant breast lesions not identified with magnetic resonance (MR) imaging.Breast tissue specimens were obtained in 464 of 967 patients who had undergone dynamic gadolinium-enhanced T1-weighted fast low-angle shot three-dimensional MR imaging of both breasts. A comparison of sensitivity, specificity, and predictive values of the prospectively recorded findings of mammography, ultrasonography (US), and MR imaging with the histopathologic results was performed with receiver operating characteristic (ROC) curve analysis. MR imaging examination findings that caused a false-negative diagnosis were reviewed to identify possible sources of error.Hi…

Quantitative contrast-enhanced myocardial perfusion magnetic resonance imaging: Simulation of bolus dispersion in constricted vessels

2009

Quantification of myocardial blood flow (MBF) by means of T 1 -weighted first-pass magnetic resonance imaging(MRI) requires knowledge of the arterial input function (AIF), which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest, which leads to systematic underestimation of the MBF. The aim of this study was to simulate the dispersion along a simplified coronary artery with different stenoses. To analyze the dispersion in vessels with typical dimensions of coronary arteries, simulations were performed using the computational fluid dynamics approach. Simulations were accomplished on straight vessels wi…

In-vitro-Untersuchung von biologischen und technischen Herzklappenprothesen im MRT: Beurteilung möglicher Anziehung und Erhitzung der Implantate

2000

PURPOSE In vitro evaluation of possible deflection and heating of present-day prosthetic heart valves during MR imaging at 1.5 T. METHODS 17 prosthetic heart valves, 12 technical and 5 biological, were investigated using a 1.5 Tesla Siemens Vision system. Deflection was measured at the edge of a 1.5 Tesla superconducting magnet. Each valve was then submerged in a vial of a 1/1 electrolyte solution and temperature was measured before and after imaging with a turbo-spin-echo sequence (TR 5200 ms, TE 138 ms, Flip angle 180 degrees, acquisition time 10.5 minutes, length of echo train 29). MR imaging was performed with phase encoding parallel and perpendicular to the plane of the valves. RESULTS…

Students’ experiences of reflective writing in physiotherapy education

2015

band through the big fingers and the first toes and instructed them to extend the band as much as possible (band exercise). Each exercise was to be performed on alternate days. Before exrcise, we obtained MR imaging using Achieva 3.0T MRI (Philips Medical Systems, Best, Netherland). The imaging technique was T2 star (repetition time, 500ms; echo time, 0.703ms; field-of-view, 480mm). After scanning, participants performed each exercise in the MRI machine. For a duration of 5min, each exercise was performed at an interval of 10 s; MRI was conducted immediately after exercise. The OsiriX imaging software was used for analysis, and we circled region of interest (ROI) multifidus muscles and the …