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Accelerated radially encoded tissue phase mapping

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Velocity measurements of the heart muscle (Tissue Phase Mapping, TPM) can be used to quantify asynchrony or abnormal motion patterns... However, long scan times restrict the clinical usability of these measurements... We investigate the use of accelerated radial acquisition to benefit from its unique motion artifact properties... Two types of segmented, triggered, and gated velocity encoding sequences were used: a Cartesian acquisition (fully sampled; R = 1) and radial acquisitions with undersampling factors of R = 1,3, and 6... Higher undersampling was analyzed from a similar radial acquisition (R = 1) of a beating heart phantom by leaving out profiles to simulate undersampling factors of R = 2 to 10... Median radial [vr(t)], circumferential [vc(t)] and longitudinal [vl(t)] velocities were obtained for each cardiac phase t and corrected by their mean velocity over time... Velocity curves were compared relative to fully sampled data (in vivo: Cartesian acquisition) by correlation coefficient CC... Image quality is comparable for Cartesian and radial acquisition with all investigated undersampling factors, although noise is slightly increased for higher R... Median velocity curves (Figure 1b) give comparable results for all acquisitions... Quantitatively, SNR is decreased to 63% of the original value for in vivo data, but SNR loss for iteratively reconstructed phantom data is 17% at worst (see Figure 2)... Median velocity curves are preserved (CC > .97, Figure 2) for all R in vivo and with the phantom... Radial TPM is feasible in vivo and yields comparable results to Cartesian TPM... Higher undersampling factors can be reached by using iterative reconstruction methods, as the phantom study suggests.

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(a) Anatomical and velocity images from Cartesian and radial acquisition in a volunteer. Although noise is slightly increased for higher undersampling, overall image quality is preserved. (b) Median radial, circumferential and longitudinal velocities of the same volunteer show almost no difference.
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Figure 1: (a) Anatomical and velocity images from Cartesian and radial acquisition in a volunteer. Although noise is slightly increased for higher undersampling, overall image quality is preserved. (b) Median radial, circumferential and longitudinal velocities of the same volunteer show almost no difference.

Mentions: Figure 1a shows anatomical and velocity images exemplarily in one volunteer. Image quality is comparable for Cartesian and radial acquisition with all investigated undersampling factors, although noise is slightly increased for higher R. Median velocity curves (Figure 1b) give comparable results for all acquisitions. Quantitatively, SNR is decreased to 63% of the original value for in vivo data, but SNR loss for iteratively reconstructed phantom data is 17% at worst (see Figure 2). Median velocity curves are preserved (CC > .97, Figure 2) for all R in vivo and with the phantom.


Accelerated radially encoded tissue phase mapping
(a) Anatomical and velocity images from Cartesian and radial acquisition in a volunteer. Although noise is slightly increased for higher undersampling, overall image quality is preserved. (b) Median radial, circumferential and longitudinal velocities of the same volunteer show almost no difference.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4042552&req=5

Figure 1: (a) Anatomical and velocity images from Cartesian and radial acquisition in a volunteer. Although noise is slightly increased for higher undersampling, overall image quality is preserved. (b) Median radial, circumferential and longitudinal velocities of the same volunteer show almost no difference.
Mentions: Figure 1a shows anatomical and velocity images exemplarily in one volunteer. Image quality is comparable for Cartesian and radial acquisition with all investigated undersampling factors, although noise is slightly increased for higher R. Median velocity curves (Figure 1b) give comparable results for all acquisitions. Quantitatively, SNR is decreased to 63% of the original value for in vivo data, but SNR loss for iteratively reconstructed phantom data is 17% at worst (see Figure 2). Median velocity curves are preserved (CC > .97, Figure 2) for all R in vivo and with the phantom.

View Article: PubMed Central - HTML

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Velocity measurements of the heart muscle (Tissue Phase Mapping, TPM) can be used to quantify asynchrony or abnormal motion patterns... However, long scan times restrict the clinical usability of these measurements... We investigate the use of accelerated radial acquisition to benefit from its unique motion artifact properties... Two types of segmented, triggered, and gated velocity encoding sequences were used: a Cartesian acquisition (fully sampled; R = 1) and radial acquisitions with undersampling factors of R = 1,3, and 6... Higher undersampling was analyzed from a similar radial acquisition (R = 1) of a beating heart phantom by leaving out profiles to simulate undersampling factors of R = 2 to 10... Median radial [vr(t)], circumferential [vc(t)] and longitudinal [vl(t)] velocities were obtained for each cardiac phase t and corrected by their mean velocity over time... Velocity curves were compared relative to fully sampled data (in vivo: Cartesian acquisition) by correlation coefficient CC... Image quality is comparable for Cartesian and radial acquisition with all investigated undersampling factors, although noise is slightly increased for higher R... Median velocity curves (Figure 1b) give comparable results for all acquisitions... Quantitatively, SNR is decreased to 63% of the original value for in vivo data, but SNR loss for iteratively reconstructed phantom data is 17% at worst (see Figure 2)... Median velocity curves are preserved (CC > .97, Figure 2) for all R in vivo and with the phantom... Radial TPM is feasible in vivo and yields comparable results to Cartesian TPM... Higher undersampling factors can be reached by using iterative reconstruction methods, as the phantom study suggests.

No MeSH data available.