scholarly journals The effect of varying spectral resolution on the quality of high spectral and spatial resolution magnetic resonance images of the breast

2003 ◽  
Vol 18 (4) ◽  
pp. 442-448 ◽  
Author(s):  
Milica Medved ◽  
Weiliang Du ◽  
Marta A. Zamora ◽  
Xiaobing Fan ◽  
Olufunmilayo I. Olopade ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
Magnetic Resonance Images

Postscript

2020 ◽  
pp. 403-404
Author(s):  
Timothy P. L. Roberts ◽  
James W. Wheless ◽  
Andrew C. Papanicolaou
Keyword(s):  
Magnetic Resonance Imaging ◽  
Electrical Conductivity ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
Inverse Modeling ◽  
Oscillatory Activity ◽  
Electric Potentials ◽  
Spatial Source

As is evident from the scientific chapters of this book, the technology of magnetoencephalography offers a combination of spatial, temporal, and spectral resolution, unique among neuroimaging technologies. While functional magnetic resonance imaging (fMRI) accommodates spatial resolution, it lacks the millisecond resolution (because of the reliance on a slow hemodynamic response) to identify subtle latency shifts, or the specificity to distinguish theta- versus alpha- versus gamma-band oscillatory activity. While electroencephalography (EEG) offers the needed temporal resolution, it fails to adequately localize brain sources, owing to the physics of inverse modeling and the dependence of scalp electric potentials on tissue electrical conductivity. Thus, although fMRI may see “activity,” it cannot characterize important attributes of its nature. Conversely, EEG may detect “anomalies” but not be able to attribute them to a particular spatial source....

scholarly journals Interobserver variability in quality assessment of magnetic resonance images

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Rafal Obuchowicz ◽  
Mariusz Oszust ◽  
Adam Piorkowski
Keyword(s):  
Magnetic Resonance ◽  
Image Quality ◽  
Quality Assessment ◽  
Image Quality Assessment ◽  
Interobserver Variability ◽  
Poor Performance ◽  
Magnetic Resonance Images ◽  
Perceptual Quality ◽  
Mr Images

Abstract Background The perceptual quality of magnetic resonance (MR) images influences diagnosis and may compromise the treatment. The purpose of this study was to evaluate how the image quality changes influence the interobserver variability of their assessment. Methods For the variability evaluation, a dataset containing distorted MRI images was prepared and then assessed by 31 experienced medical professionals (radiologists). Differences between observers were analyzed using the Fleiss’ kappa. However, since the kappa evaluates the agreement among radiologists taking into account aggregated decisions, a typically employed criterion of the image quality assessment (IQA) performance was used to provide a more thorough analysis. The IQA performance of radiologists was evaluated by comparing the Spearman correlation coefficients, ρ, between individual scores with the mean opinion scores (MOS) composed of the subjective opinions of the remaining professionals. Results The experiments show that there is a significant agreement among radiologists (κ=0.12; 95% confidence interval [CI]: 0.118, 0.121; P<0.001) on the quality of the assessed images. The resulted κ is strongly affected by the subjectivity of the assigned scores, separately presenting close scores. Therefore, the ρ was used to identify poor performance cases and to confirm the consistency of the majority of collected scores (ρmean = 0.5706). The results for interns (ρmean = 0.6868) supports the finding that the quality assessment of MR images can be successfully taught. Conclusions The agreement observed among radiologists from different imaging centers confirms the subjectivity of the perception of MR images. It was shown that the image content and severity of distortions affect the IQA. Furthermore, the study highlights the importance of the psychosomatic condition of the observers and their attitude.

scholarly journals Influence of partial k-space filling on the quality of magnetic resonance images

2016 ◽  
Vol 49 (3) ◽  
pp. 158-164
Author(s):  
Tiago da Silva Jornada ◽  
Camila Hitomi Murata ◽  
Regina Bitelli Medeiros
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Magnetic Resonance Images ◽  
Resonance Imaging ◽  
Signal To Noise ◽  
T1 And T2 ◽  
Space Acquisition ◽  
Magnetic Resonance Imaging Equipment

Abstract Objective: To study the influence that the scan percentage tool used in partial k-space acquisition has on the quality of images obtained with magnetic resonance imaging equipment. Materials and Methods: A Philips 1.5 T magnetic resonance imaging scanner was used in order to obtain phantom images for quality control tests and images of the knee of an adult male. Results: There were no significant variations in the uniformity and signal-to-noise ratios with the phantom images. However, analysis of the high-contrast spatial resolution revealed significant degradation when scan percentages of 70% and 85% were used in the acquisition of T1- and T2-weighted images, respectively. There was significant degradation when a scan percentage of 25% was used in T1- and T2-weighted in vivo images (p ≤ 0.01 for both). Conclusion: The use of tools that limit the k-space is not recommended without knowledge of their effect on image quality.

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