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1122 Regional differences in signal gain in cardiac mri at 3.0 tesla. An intra individual comparison of different sequences

Purpose

To compare signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) of different regions of the left ventricle using SSFP- and FSE-black-blood-imaging techniques at 1.5 and 3.0 T on volunteers and to examine signal behaviour in SSFP-imaging depending on the image-plane.

Methods

18 healthy volunteers, mean age 28 ( ± 5), underwent cardiac mri examination using a GE Signa 1.5 T and a GE Signa 3.0 T system with Excite technology.

Signal reception was performed using a four-channel phased-array-coil of identical coil design for both field strengths. Breath-held ECG triggered 2D-Cine imaging was performed at the midventricular level of the left ventricle using a short-axis-view (SA), a long-axis two chamber view (LA) and a four-chamber-view (4 CV) with "steady-state-free-precession" (SSFP) FIESTA-Sequences. Fast-Spin-Echo-sequences (FSE) in T1-(Double-IR), T2 and T1-Stir (Triple-IR)-weighting were performed at the midventricular level of the left ventricle in the SA-view. For the SA-view SNR and CNR of the whole left ventricle as well as for the four LV-segments: septum (S), anterior- (AW), posterior- (PW) and lateral wall (LW) was calculated. For the LA- and 4CV-view SNR and CNR of the whole left ventricle was calculated.

Results

The SNR and CNR for the whole left ventricle was increased in all FSE- and all SSFP-sequences at 3.0 T (FSE: SNR min. 8%, max. 25%/CNR: min.11%, max. 25%; FIESTA SNR: max. 129%, min 107%, CNR: max.50%, min. 32%). In all FSE-sequences there were differences in SNR and CNR depending on the heart segment at both field strengths. At 3.0 T the differences were smaller than at 1.5 T. There was also a difference in the increase of SNR and CNR depending on the region of the LV. In the FSE-sequences the highest gain in SNR/CNR was obtained in the AW and LW (SNR: min.17%, max. 39%), the lowest gain in the septum (SNR: min. -1%, max. 9%). At both field strengths the lowest SNR and CNR was found in the PW. At the FIESTA-Sequences there was found a dependence of the signal behaviour on the image plane with the highest SNR and CNR in the SA at both field strengths. In the SA-view differences in signal-behaviour between the LV-segment again were found, with the highest SNR and the highest increase of SNR (129%) in the septum at both field strengths. In contrast to the FSE-Sequences, at the FIESTA-sequences the differences between the LV-segments were smaller at 1.5 T than at 3.0 T.

Conclusion

The mean SNR and CNR was increased at 3.0 T compared to 1.5 T at both, FSE- and FIESTA-Sequences. Regional differences in signal-behaviour exist at both field strengths. The heart segments benefit to a different degree from the higher field strength. At both field strengths the lowest SNR/CNR is to be found in the PW, which is prior to signal inhomogenities. In Cine-Imaging with SSFP these signal inhomogenities are increased at 3.0 T. Due to this the improvement of the design of cardiac mri sequences at higher field strengths is mandatory.

Author information

Correspondence to Patrick Freyhardt.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Freyhardt, P., Spors, B., Hamm, B. et al. 1122 Regional differences in signal gain in cardiac mri at 3.0 tesla. An intra individual comparison of different sequences. J Cardiovasc Magn Reson 10, A247 (2008). https://doi.org/10.1186/1532-429X-10-S1-A247

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Keywords

  • Left Ventricle
  • Field Strength
  • Lateral Wall
  • High Field Strength
  • Chamber View