Edge sharpness assessment by parametric modeling: Application to magnetic resonance imaging

Ahmad, Rizwan; Ding, Yu; Simonetti, Orlando P.

doi:10.1002/cmr.a.21339

Cited by 38 publications

(31 citation statements)

References 26 publications

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“…A comparison of the endocardial sharpness was performed in the septal wall, where there are fewest papillary muscles and trabeculations and little off‐resonance artefact. Line profiles were drawn from the LV centroid to the epicardium and fitted with the sigmoid function

f (x, a_{0}, a_{1}, a_{2}, s) = \frac{a_{1}}{1 + 10^{s (a_{0} - x)}} + a_{2}

, with x increasing positively along the profile. The parameters a i are used to quantify the location (a 0 ) and amplitude of upper (a 1 + a 2 ) and lower plateau (a 2 ) of the profile and s the growth rate or sharpness of the line profiles.…”

Section: Methodsmentioning

confidence: 99%

High resolution in‐vivo DT‐CMR using an interleaved variable density spiral STEAM sequence

Gorodezky

Ferreira

Nielles‐Vallespin

et al. 2018

Magnetic Resonance in Med

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Purpose Diffusion tensor cardiovascular magnetic resonance (DT‐CMR) has a limited spatial resolution. The purpose of this study was to demonstrate high‐resolution DT‐CMR using a segmented variable density spiral sequence with correction for motion, off‐resonance, and T2*‐related blurring. Methods A single‐shot stimulated echo acquisition mode (STEAM) echo‐planar‐imaging (EPI) DT‐CMR sequence at 2.8 × 2.8 × 8 mm3 and 1.8 × 1.8 × 8 mm3 was compared to a single‐shot spiral at 2.8 × 2.8 × 8 mm3 and an interleaved spiral sequence at 1.8 × 1.8 × 8 mm3 resolution in 10 healthy volunteers at peak systole and diastasis. Motion‐induced phase was corrected using the densely sampled central k‐space data of the spirals. STEAM field maps and T2* measures were obtained using a pair of stimulated echoes each with a double spiral readout, the first used to correct the motion‐induced phase of the second. Results The high‐resolution spiral sequence produced similar DT‐CMR results and quality measures to the standard‐resolution sequence in both cardiac phases. Residual differences in fractional anisotropy and helix angle gradient between the resolutions could be attributed to spatial resolution and/or signal‐to‐noise ratio. Data quality increased after both motion‐induced phase correction and off‐resonance correction, and sharpness increased after T2* correction. The high‐resolution EPI sequence failed to provide sufficient data quality for DT‐CMR reconstruction. Conclusion In this study, an in vivo DT‐CMR acquisition at 1.8 × 1.8 mm2 in‐plane resolution was demonstrated using a segmented spiral STEAM sequence. Motion‐induced phase and off‐resonance corrections are essential for high‐resolution spiral DT‐CMR. Segmented variable density spiral STEAM was found to be the optimal method for acquiring high‐resolution DT‐CMR data.

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f (x, a_{0}, a_{1}, a_{2}, s) = \frac{a_{1}}{1 + 10^{s (a_{0} - x)}} + a_{2}

Section: Methodsmentioning

confidence: 99%

High resolution in‐vivo DT‐CMR using an interleaved variable density spiral STEAM sequence

Gorodezky

Ferreira

Nielles‐Vallespin

et al. 2018

Magnetic Resonance in Med

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show abstract

“…The signal intensity (SI) along the profile was fitted to a sigmoid function described by:

SI (();,,,, x, c_{0}, c_{1}, c_{2}, s) = \frac{c_{1}}{1 + 10^{s ((), c_{0} - x)}} + c_{2}

where x (independent variable) is the distance, c 0 is the center location, c 1 describes the vertical range, c 2 determines the vertical offset and s defines the sharpness of the sigmoid. A least‐squares curve fit was chosen and the parameter s provides a measure of edge sharpness …”

Section: Methodsmentioning

confidence: 99%

Multiband diffusion‐weighted MRI of the eye and orbit free of geometric distortions using a RARE‐EPI hybrid

et al. 2018

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Diffusion-weighted imaging (DWI) provides information on tissue microstructure. Single-shot echo planar imaging (EPI) is the most common technique for DWI applications in the brain, but is prone to geometric distortions and signal voids. Rapid acquisition with relaxation enhancement [RARE, also known as fast spin echo (FSE)] imaging presents a valuable alternative to DWI with high anatomical accuracy. This work proposes a multi-shot diffusion-weighted RARE-EPI hybrid pulse sequence, combining the anatomical integrity of RARE with the imaging speed and radiofrequency (RF) power deposition advantage of EPI. The anatomical integrity of RARE-EPI was demonstrated and quantified by center of gravity analysis for both morphological images and diffusion-weighted acquisitions in phantom and in vivo experiments at 3.0 T and 7.0 T. The results indicate that half of the RARE echoes in the echo train can be replaced by EPI echoes whilst maintaining anatomical accuracy. The reduced RF power deposition of RARE-EPI enabled multiband RF pulses facilitating simultaneous multi-slice imaging. This study shows that diffusion-weighted RARE-EPI has the capability to acquire high fidelity, distortion-free images of the eye and the orbit. It is shown that RARE-EPI maintains the immunity to B inhomogeneities reported for RARE imaging. This benefit can be exploited for the assessment of ocular masses and pathological changes of the eye and the orbit.

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“…To evaluate sharpness, we analyzed the rise-distance (10 to 90% of the peak value) [22] of the intensity changes across IVS edges. Finally, the readers interactively drew endocardial contours to measure LV areas on ED and ES images, to compare LV areas measured on BH vs. FB cines.…”

Section: Methodsmentioning

confidence: 99%

Two-dimensional XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration

Piekarski

Chițiboi

Ramb

et al. 2017

Magn Reson Mater Phy

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Object Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMR). We evaluated whether a free-breathing (FB) radial imaging CCMR sequence with compressed sensing reconstruction (eXtra-Dimension (e.g. cardiac and respiratory phases) Golden-angle RAdial Sparse Parallel, or XD-GRASP) could provide better image quality than a conventional Cartesian breath-held (BH) sequence, in an unselected population of patients undergoing clinical CCMR. Material and Methods 101 patients who underwent BH and FB imaging in a mid-ventricular short-axis plane at a matching location were included. Visual and quantitative image analysis was performed by two blinded experienced readers, using a 5-point qualitative scale to score overall image quality and visual signal-to-noise ratio (SNR) grade, with measures of noise and sharpness. End-diastole (ED) and end-systole (ES) left-ventricular areas were also measured and compared for both BH and FB images. Results Image quality was generally better with the BH cines (overall quality grade BH vs FB: 4 vs 2.9, p<0.001; noise 0.06 vs 0.08 p< 0.001; SNR grade: 4.1 vs 3, p<0.001), except for sharpness (p=0.48). There were no significant differences between BH and FB images regarding ED or ES areas (p=0.35 and 0.12). 18 of the 101 patients had impaired BH image quality (grades 1 or 2). In this subgroup, image quality of the FB images was better (p=0.0032), as was the SNR grade (p=0.003), but there were no significant differences regarding noise and sharpness (p=0.45, p=0.47). Conclusion Although FB XD-GRASP CCMR was visually inferior to conventional BH cardiac cine in general, it provided improved image quality in the subgroup of patients presenting respiratory motion-induced artifacts on breath-held images.

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Edge sharpness assessment by parametric modeling: Application to magnetic resonance imaging

Cited by 38 publications

References 26 publications

High resolution in‐vivo DT‐CMR using an interleaved variable density spiral STEAM sequence

High resolution in‐vivo DT‐CMR using an interleaved variable density spiral STEAM sequence

Multiband diffusion‐weighted MRI of the eye and orbit free of geometric distortions using a RARE‐EPI hybrid

Two-dimensional XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration

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