scholarly journals Realistic Dynamic Numerical Phantom for MRI of the Upper Vocal Tract

2020 ◽  
Vol 6 (9) ◽  
pp. 86
Author(s):  
Joe Martin ◽  
Matthieu Ruthven ◽  
Redha Boubertakh ◽  
Marc E. Miquel
Keyword(s):  
Spatial Interpolation ◽  
Parallel Imaging ◽  
Vocal Tract ◽  
Frame Rate ◽  
The Novel ◽  
Sampling Strategies ◽  
Sampling Schemes ◽  
Multiple Sampling ◽  
Lower Frame ◽  
Space Data

Dynamic and real-time MRI (rtMRI) of human speech is an active field of research, with interest from both the linguistics and clinical communities. At present, different research groups are investigating a range of rtMRI acquisition and reconstruction approaches to visualise the speech organs. Similar to other moving organs, it is difficult to create a physical phantom of the speech organs to optimise these approaches; therefore, the optimisation requires extensive scanner access and imaging of volunteers. As previously demonstrated in cardiac imaging, realistic numerical phantoms can be useful tools for optimising rtMRI approaches and reduce reliance on scanner access and imaging volunteers. However, currently, no such speech rtMRI phantom exists. In this work, a numerical phantom for optimising speech rtMRI approaches was developed and tested on different reconstruction schemes. The novel phantom comprised a dynamic image series and corresponding k-space data of a single mid-sagittal slice with a temporal resolution of 30 frames per second (fps). The phantom was developed based on images of a volunteer acquired at a frame rate of 10 fps. The creation of the numerical phantom involved the following steps: image acquisition, image enhancement, segmentation, mask optimisation, through-time and spatial interpolation and finally the derived k-space phantom. The phantom was used to: (1) test different k-space sampling schemes (Cartesian, radial and spiral); (2) create lower frame rate acquisitions by simulating segmented k-space acquisitions; (3) simulate parallel imaging reconstructions (SENSE and GRAPPA). This demonstrated how such a numerical phantom could be used to optimise images and test multiple sampling strategies without extensive scanner access.

Error analysis of spatial interpolation of soil texture under different sampling schemes

2014 ◽  
Vol 22 (2) ◽  
pp. 217-224
Author(s):  
Houlong JIANG ◽  
Shuduan LIU ◽  
Anding XU ◽  
Chao YANG
Keyword(s):  
Error Analysis ◽  
Soil Texture ◽  
Spatial Interpolation ◽  
Sampling Schemes

scholarly journals Spatial mapping of ground-based observations of total ozone

2015 ◽  
Vol 8 (10) ◽  
pp. 4487-4505 ◽  
Author(s):  
K.-L. Chang ◽  
S. Guillas ◽  
V. E. Fioletov
Keyword(s):  
Spatial Interpolation ◽  
Stochastic Partial Differential Equation ◽  
Positive Impact ◽  
The Novel ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Source Of Information ◽  
Total Column ◽  
Ozone Levels

Abstract. Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with the covariance-based kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to the covariance-based kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

scholarly journals Teleassessment of Gait and Gait Aids: Validity and Interrater Reliability

2020 ◽  
Vol 100 (4) ◽  
pp. 708-717
Author(s):  
Kavita Venkataraman ◽  
Kristopher Amis ◽  
Lawrence R Landerman ◽  
Kevin Caves ◽  
Gerald C Koh ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Interrater Reliability ◽  
Video Quality ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Slow Motion ◽  
Frame Rate ◽  
Normal Speed ◽  
Lower Frame ◽  
Rehabilitation Needs

Abstract Background Gait and mobility aid assessments are important components of rehabilitation. Given the increasing use of telehealth to meet rehabilitation needs, it is important to examine the feasibility of such assessments within the constraints of telerehabilitation. Objective The objective of this study was to examine the reliability and validity of the Tinetti Performance-Oriented Mobility Assessment gait scale (POMA-G) and cane height assessment under various video and transmission settings to demonstrate the feasibility of teleassessment. Design This repeated-measures study compared the test performances of in-person, slow motion (SM) review, and normal-speed (NS) video ratings at various fixed frame rates (8, 15, and 30 frames per second) and bandwidth (128, 384, and 768 kB/s) configurations. Methods Overall bias, validity, and interrater reliability were assessed for in-person, SM video, and NS video ratings, with SM video rating as the gold standard, as well as for different frame rate and bandwidth configurations within NS videos. Results There was moderate to good interrater reliability for the POMA-G (intraclass correlation coefficient [ICC] = 0.66–0.77 across all configurations) and moderate validity for in-person (β = 0.62; 95% confidence interval [CI] = 0.37–0.87) and NS video (β = 0.74; 95% CI = 0.67–0.80) ratings compared with the SM video rating. For cane height, interrater reliability was good (ICC = 0.66–0.77), although it was significantly lower at the lowest frame rate (8 frames per second) (ICC = 0.66; 95% CI = 0.54–0.76) and bandwidth (128 kB/s) (ICC = 0.69; 95% CI = 0.57–0.78) configurations. Validity for cane height was good for both in-person (β = 0.80; 95% CI = 0.62–0.98) and NS video (β = 0.86; 95% CI = 0.81–0.90) ratings compared with SM video rating. Limitations Some lower frame rate and bandwidth configurations may limit the reliability of remote cane height assessments. Conclusions Teleassessment for POMA-G and cane height using typically available internet and video quality is feasible, valid, and reliable.

Effect of Video Frame Rate on Subjects’ Ability to Shadow One of Two Competing Verbal Passages

1994 ◽  
Vol 37 (5) ◽  
pp. 1204-1210 ◽  
Author(s):  
Melanie Vitkovitch ◽  
Paul Barber
Keyword(s):  
Visual Cues ◽  
Visual Image ◽  
Frame Rate ◽  
Video Frame ◽  
Communication Link ◽  
Subject Group ◽  
Video Telephone ◽  
Improved Performance ◽  
Lower Frame ◽  
Video Frame Rate

In a study addressing future use of video-telephone systems, the ability of 52 young adults with normal hearing to shadow verbal passages was assessed when they could both hear and observe the speaker. This performance was compared to performance in an audio-alone condition. The passages were presented against an irrelevant background message. Effects of varying the video frame rate (i.e., the rate at which frames were sampled) were examined, using rates of 8.3, 12.5, 16.7, and 25 Hz. The presence of the visual image of the relevant speaker always improved performance when compared with a baseline audio-alone condition. The motion of the speaker’s face may generally support the focusing of attention on the target message. However, effects of video frame rate were also apparent, suggesting that specific visual cues became available as the temporal resolution improved. When frame rates of 8.3 Hz and the maximum available rate of 25 Hz were compared, shadowing performance was significantly better across the subject group at the higher frame rate. The comparison of frame rates of 12.5 and 25 Hz did not show reliably improved performance across the whole subject group at 25 Hz, although a small number of subjects seemed to benefit. This suggests there may be some differences in the visual cues used by subjects and consequent differences in the way individuals perform under different frame rates. Performance at 16.7 and 25 Hz did not differ, and this is consistent with previous research that tested people with hearing loss. A frame rate of 16.7 Hz may therefore be adequate for the transmission of facial images via a video communication link to a broad range of users; at the lower frame rates, the performance of users is likely to suffer.

scholarly journals Spatial mapping of ground-based observations of total ozone

2015 ◽  
Vol 8 (4) ◽  
pp. 3967-4009 ◽  
Author(s):  
K.-L. Chang ◽  
S. Guillas ◽  
V. E. Fioletov
Keyword(s):  
Spatial Interpolation ◽  
Stochastic Partial Differential Equation ◽  
Positive Impact ◽  
The Novel ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Source Of Information ◽  
Total Column ◽  
Ozone Levels

Abstract. Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

scholarly journals Joint reconstruction framework of compressed sensing and nonlinear parallel imaging for dynamic cardiac magnetic resonance imaging

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhanqi Hu ◽  
Cailei Zhao ◽  
Xia Zhao ◽  
Lingyu Kong ◽  
Jun Yang ◽  
...  
Keyword(s):  
Compressed Sensing ◽  
Parallel Imaging ◽  
Imaging Technique ◽  
Temporal Variations ◽  
Cine Mri ◽  
Reconstruction Process ◽  
Parallel Imaging Technique ◽  
In Vivo Experiments ◽  
Space Data

AbstractCompressed Sensing (CS) and parallel imaging are two promising techniques that accelerate the MRI acquisition process. Combining these two techniques is of great interest due to the complementary information used in each. In this study, we proposed a novel reconstruction framework that effectively combined compressed sensing and nonlinear parallel imaging technique for dynamic cardiac imaging. Specifically, the proposed method decouples the reconstruction process into two sequential steps: In the first step, a series of aliased dynamic images were reconstructed from the highly undersampled k-space data using compressed sensing; In the second step, nonlinear parallel imaging technique, i.e. nonlinear GRAPPA, was utilized to reconstruct the original dynamic images from the reconstructed k-space data obtained from the first step. In addition, we also proposed a tailored k-space down-sampling scheme that satisfies both the incoherent undersampling requirement for CS and the structured undersampling requirement for nonlinear parallel imaging. The proposed method was validated using four in vivo experiments of dynamic cardiac cine MRI with retrospective undersampling. Experimental results showed that the proposed method is superior at reducing aliasing artifacts and preserving the spatial details and temporal variations, compared with the competing k-t FOCUSS and k-t FOCUSS with sensitivity encoding methods, with the same numbers of measurements.

scholarly journals Joint Reconstruction Framework of Compressed Sensing and Nonlinear Parallel Imaging for Dynamic Cardiac Magnetic Resonance Imaging

2021 ◽  
Author(s):  
Zhanqi Hu ◽  
Cailei Zhao ◽  
Xia Zhao ◽  
Lingyu Kong ◽  
Jun Yang ◽  
...  
Keyword(s):  
Compressed Sensing ◽  
Parallel Imaging ◽  
Dynamic Imaging ◽  
Cine Mri ◽  
Reconstruction Process ◽  
Joint Reconstruction ◽  
Cardiac Cine ◽  
Nonlinear Technique ◽  
Space Data

Abstract Compressed Sensing (CS) and parallel imaging are two promising techniques that accelerate the MRI acquisition process. Combining these two techniques is of great interest due to the complementary information used in each. In this study, we propose a new reconstruction framework for dynamic cardiac imaging that takes advantage of both CS-based dynamic imaging and one nonlinear parallel imaging technique. The method decouples the reconstruction process into two sequential steps: use CS to reconstruct a series of aliased dynamic images from the highly undersampled k-space data; use nonlinear GRAPPA method, one nonlinear technique of parallel imaging, to reconstruct the original dynamic images from the k-space data that has been reconstructed by CS. The sampling scheme of the proposed method is designed to simultaneously satisfy the incoherent undersampling requirement for CS and the structured undersampling requirement for nonlinear parallel imaging. Four in vivo experiments of dynamic cardiac cine MRI were carried out with retrospective undersampling to evaluate the performance of the proposed method. Experiments show the proposed method of dynamic cardiac cine MRI is superior at reducing aliasing artifacts and preserving the spatial details and temporal variations, when compared with k-t FOCUSS and k-t FOCUSS with sensitivity encoding, using the same numbers of measurements. The proposed joint reconstruction framework effectively combines the CS method and one nonlinear technique of parallel imaging, and improves the image quality of dynamic cardiac cine MRI reconstruction when comparing to the state-of-the-art methods.

scholarly journals Feasibility and Accuracy of a Fully Automated Right Ventricular Quantification Software With Three-Dimensional Echocardiography: Comparison With Cardiac Magnetic Resonance

2021 ◽  
Vol 8 ◽  
Author(s):  
Ashfaq Ahmad ◽  
He Li ◽  
Xiaojing Wan ◽  
Yi Zhong ◽  
Yanting Zhang ◽  
...  
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Right Ventricular ◽  
Three Dimensional ◽  
Frame Rate ◽  
The Novel ◽  
Systolic Volume ◽  
Dimensional Echocardiography ◽  
Three Dimensional Echocardiography ◽  
Rv Function

Background: A novel, fully automated right ventricular (RV) software for three-dimensional quantification of RV volumes and function was developed. The direct comparison of the software performance with cardiac magnetic resonance (CMR) was limited. Therefore, the aim of this study was to test the feasibility, accuracy, and reproducibility of a fully automated RV quantification software against CMR imaging as a reference.Methods: A total of 170 patients who underwent both CMR and three-dimensional echocardiography were enrolled. RV end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), and RV ejection fraction (RVEF) were obtained using fully automated three-dimensional RV quantification software and compared with a CMR reference. For inter-technical agreement, Spearman correlation and Bland–Altman analysis were used.Results: The fully automated RV quantification software was feasible in 149 patients. RVEDV and RVESV were underestimated, and RVEF was overestimated compared with CMR values. RV measurements obtained from the manual editing method correlated better with CMR values than that without manual editing (RVEDV, 0.924 vs. 0.794: RVESV, 0.955 vs. 0.854; RVEF, 0.941 vs. 0.781 respectively, all p < 0.0001) with less bias and narrower limit of agreement (LOA). The bias and LOA for RV volumes and EF using the automated software without and with manual editing were greater in patients with severely impaired RV function or low frame rate than those with normal and mild impaired RV function, or high frame rate. The fully automated RV three-dimensional measurements were highly reproducible.Conclusion: The novel fully automated RV software shows good feasibility and reproducibility, and the measurements had a high correlation with CMR values. These findings support the routine application of the novel 3D automated RV software in clinical practice.

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