Magnetic Resonance
Recently Published Documents


TOTAL DOCUMENTS

179669
(FIVE YEARS 50764)

H-INDEX

393
(FIVE YEARS 87)

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Anders Nelsson ◽  
Mikael Kanski ◽  
Henrik Engblom ◽  
Martin Ugander ◽  
Marcus Carlsson ◽  
...  

Abstract Background Increased pulmonary blood volume (PBV) is a measure of congestion and is associated with an increased risk of cardiovascular events. PBV can be quantified using cardiovascular magnetic resonance (CMR) imaging as the product of cardiac output and pulmonary transit time (PTT), the latter measured from the contrast time-intensity curves in the right and left side of the heart from first-pass perfusion (FPP). Several methods of estimating PTT exist, including pulmonary transit beats (PTB), peak-to-peak, and center of gravity (CoG). The aim of this study was to determine the accuracy and precision for these methods of quantifying the PBV, taking the left atrium volume (LAV) into consideration. Methods Fifty-eight participants (64 ± 11 years, 24 women) underwent 1.5 T CMR. PTT was quantified from (1) a basal left ventricular short-axis image (FPP), and (2) the reference method with a separate contrast administration using an image intersecting the pulmonary artery (PA) and the LA (CoG(PA-LA)). Results Compared to the reference, PBV for (a) PTB(FPP) was 14 ± 17% larger, (b) peak-peak(FPP) was 17 ± 16% larger, and (c) CoG(FPP) was 18 ± 10% larger. Subtraction of the LAV (available for n = 50) decreased overall differences to − 1 ± 19%, 2 ± 18%, and 3 ± 12% for PTB(FPP), peak-peak(FPP), and CoG(FPP), respectively. Lowest interobserver variability was seen for CoG(FPP) (− 2 ± 7%). Conclusions CoG(PA-LA) and FPP methods measured the same PBV only when adjusting for the LAV, since FPP inherently quantifies a volume consisting of PBV + LAV. CoG(FPP) had the best precision and lowest interobserver variability among the FPP methods of measuring PBV. Graphical abstract


2021 ◽  
Vol 23 (1) ◽  
Author(s):  
James T. Brown ◽  
Tushar Kotecha ◽  
Jennifer A. Steeden ◽  
Marianna Fontana ◽  
Christopher P. Denton ◽  
...  

Abstract Background Exercise intolerance in systemic sclerosis (SSc) is typically attributed to cardiopulmonary limitations. However, problems with skeletal muscle oxygen extraction have not been fully investigated. This study used cardiovascular magnetic resonance (CMR)-augmented cardiopulmonary exercise testing (CMR-CPET) to simultaneously measure oxygen consumption and cardiac output. This allowed calculation of arteriovenous oxygen content gradient, a recognized marker of oxygen extraction. We performed CMR-CPET in 4 groups: systemic sclerosis (SSc); systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH); non-connective tissue disease pulmonary hypertension (NC-PAH); and healthy controls. Methods We performed CMR-CPET in 60 subjects (15 in each group) using a supine ergometer following a ramped exercise protocol until exhaustion. Values for oxygen consumption, cardiac output and oxygen content gradient, as well as ventricular volumes, were obtained at rest and peak-exercise for all subjects. In addition, T1 and T2 maps were acquired at rest, and the most recent clinical measures (hemoglobin, lung function, 6-min walk, cardiac and catheterization) were collected. Results All patient groups had reduced peak oxygen consumption compared to healthy controls (p < 0.022). The SSc and SSc-PAH groups had reduced peak oxygen content gradient compared to healthy controls (p < 0.03). Conversely, the SSc-PAH and NC-PH patients had reduced peak cardiac output compared to healthy controls and SSc patients (p < 0.006). Higher hemoglobin was associated with higher peak oxygen content gradient (p = 0.025) and higher myocardial T1 was associated with lower peak stroke volume (p = 0.011). Conclusions Reduced peak oxygen consumption in SSc patients is predominantly driven by reduced oxygen content gradient and in SSc-PAH patients this was amplified by reduced peak cardiac output. Trial registration The study is registered with ClinicalTrials.gov Protocol Registration and Results System (ClinicalTrials.gov ID: 100358).


2021 ◽  
Vol 27 (40) ◽  
pp. 6825-6843
Author(s):  
Charles E Hill ◽  
Luca Biasiolli ◽  
Matthew D Robson ◽  
Vicente Grau ◽  
Michael Pavlides

2021 ◽  
Vol 11 ◽  
Author(s):  
Jing Wang ◽  
Xiaoping Yi ◽  
Yan Fu ◽  
Peipei Pang ◽  
Huihuang Deng ◽  
...  

PurposeEarly recurrence of glioblastoma after standard treatment makes patient care challenging. This study aimed to assess preoperative magnetic resonance imaging (MRI) radiomics for predicting early recurrence of glioblastoma.Patients and MethodsA total of 122 patients (training cohort: n = 86; validation cohort: n = 36) with pathologically confirmed glioblastoma were included in this retrospective study. Preoperative brain MRI images were analyzed for both radiomics and the Visually Accessible Rembrandt Image (VASARI) features of glioblastoma. Models incorporating MRI radiomics, the VASARI parameters, and clinical variables were developed and presented in a nomogram. Performance was assessed based on calibration, discrimination, and clinical usefulness.ResultsThe nomogram consisting of the radiomic signatures, the VASARI parameters, and blood urea nitrogen (BUN) values showed good discrimination between the patients with early recurrence and those with later recurrence, with an area under the curve of 0.85 (95% CI, 0.77-0.94) in the training cohort and 0.84 [95% CI, 0.71-0.97] in the validation cohort. Decision curve analysis demonstrated favorable clinical application of the nomogram.ConclusionThis study showed the potential usefulness of preoperative brain MRI radiomics in predicting the early recurrence of glioblastoma, which should be helpful in personalized management of glioblastoma.


2021 ◽  
Vol 11 ◽  
Author(s):  
Giorgio Volpentesta ◽  
Giuseppe Donato ◽  
Elisabetta Ferraro ◽  
Chiara Mignogna ◽  
Riccardo Radaelli ◽  
...  

Imaging limitations, invasive tissue biopsies and poor information over the course of treatment to evaluate ‘real-time’ tumor dynamics justify the emerging use of liquid biopsies in the field of brain tumors. Circulating tumor cells (CTCs) from high-grade astrocytomas might reach the circulation by crossing the blood–brain barrier. Here, for the first time, CTCs cytology in a case of pylocitic astrocytoma is described. An obstructive hydrocephalous due to a lateral mesencephalic tectum mass occluding the Silvio Aqueduct was diagnosed in a young, 18 years old, male. Considering the location of the tumor and the rapid deterioration of the neurological status, it has been decided to urgency treat the patient with ventriculoperitoneal shunting. Magnetic resonance imaging showed a nodular shaped lesion localized within the left lateral mesencephalic tectum. Stereotactic biopsy was not approachable due significant risk of neurological consequences. The diagnosis was performed by blood sampling, a non-invasive procedure for the patient, in order to provide tumor information. Cytopathological features on detected circulating atypical GFAP positive cells led to pilocytic diagnosis confirmed by the patient’s 68 months outcome.


2021 ◽  
Author(s):  
Franziska Seidel ◽  
Titus Kuehne ◽  
Sebastian Kelle ◽  
Patrick Doeblin ◽  
Victoria Zieschang ◽  
...  

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Soojung Na ◽  
Dongil Chung ◽  
Andreas Hula ◽  
Ofer Perl ◽  
Jennifer Jung ◽  
...  

The controllability of our social environment has a profound impact on our behavior and mental health. Nevertheless, neurocomputational mechanisms underlying social controllability remain elusive. Here, 48 participants performed a task where their current choices either did (Controllable), or did not (Uncontrollable), influence partners’ future proposals. Computational modeling revealed that people engaged a mental model of forward thinking (FT; i.e., calculating the downstream effects of current actions) to estimate social controllability in both Controllable and Uncontrollable conditions. A large-scale online replication study (n=1342) supported this finding. Using functional magnetic resonance imaging (n=48), we further demonstrated that the ventromedial prefrontal cortex (vmPFC) computed the projected total values of current actions during forward planning, supporting the neural realization of the forward-thinking model. These findings demonstrate that humans use vmPFC-dependent FT to estimate and exploit social controllability, expanding the role of this neurocomputational mechanism beyond spatial and cognitive contexts.


2021 ◽  
Vol 9 ◽  
Author(s):  
Irena Zivkovic

Moving to the ultrahigh field magnetic resonance imaging (UHF MRI) brought many benefits such as potentially higher signal-to-noise ratio, contrast-to-noise ratio, and improved spectral resolution. The UHF MRI regime also introduced some challenges which could prevent full exploitation of mentioned advantages. A higher static magnetic field means increase in Larmor frequency, which further implies the shorter wavelength in a tissue. The shorter wavelength causes interferences of the RF signal and inhomogeneous excitation, which can be partially resolved by the introduction of the multichannel coil arrays. The biggest problem in UHF multichannel densely populated arrays is the existence of the interelement coupling, which should be minimized as much as possible. This article presents the nonconventional, recently developed decoupling techniques used in UHF MRI.


Author(s):  
David H. Ballard ◽  
Daniel R. Ludwig ◽  
Tyler J. Fraum ◽  
Amber Salter ◽  
Vamsi R. Narra ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document