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Further refining stress perfusion imaging: the initial clinical impact of a 32 channel surface coil

Introduction

Adenosine stress cardiac magnetic resonance (CMR) is widely accepted as a safe, reliable and reproducible investigation to identify areas of inducible ischaemia. Optimal images depend on sequence parameters, including a large field of view (FOV) coverage, a high signal to noise ratio (SNR) and minimal artefact. 32-channel surface coils may provide a higher SNR over a larger FOV compared to standard 5-channel coils.

Purpose

We therefore examined if the use of a 32-channel coil led to a significant improvement in observed image quality.

Methods

50 perfusion scans were performed using a Philips Achieva CV 1.5 T MRI scanner (Philips Medical Systems), using either a 5 or 32-channel coil (25 patients each) using standardised protocols. First-pass perfusion-imaging was performed using a 0.05 mmol/kg gadolinium bolus during induced stress (adenosine at 140 mcg/Kg/min for 3 minutes). 3 short axis slices were acquired per cardiac cycle using a single-shot prospectively-gated balanced TFE sequence (TR 2.5 ms TE 1.3 ms, flip-angle 50° and voxel size of 2.8 × 2.8 × 10 mm). The cine images were optimised using dedicated software (Philips) and reviewed by two blinded CMR specialists in a randomised and anonymised sequence. Each video was scored on a scale of 1-5 (1 Non diagnostic, 2 Poor, 3 Adequate, 4 Good, 5 Excellent). The scores for each coil were compared using the Mann-Whitney test. Observer scores were compared using Bland-Altman analysis. Phantom studies were performed using identical acquisition parameters with acceleration factors of 2, 2.3, 2.5, 2.7 and 3. Mean signal and standard deviation were measured; from this, the SNR was calculated and compared for each coil using a Students t-test.

Results

There was a significant improvement in image quality score using the 32-channel coil compared to the 5-channel coil for observer 1 (mean score 4.1 ± 0.7 vs. 3.5 ± 1 p = 0.04), observer 2 (mean score 3.4 ± 0.7 vs. 3.0 ± 0.6 p = 0.02) and with both observers' scores combined (mean score 3.8 ± 0.7 vs. 3.2 ± 0.9 p = 0.002). The mean difference in scores was 0.6 ± 1.7. The SNR was higher for the 32-channel coil (mean SNR 203 ± 20 vs. 159 ± 12 p = 0.003). The mean patient age was 62 ± 11 years and 50% of patients were male. The cohorts were matched for age, gender and peak heart rate during stress.

Conclusion

The 32-channel coil produces significantly higher quality images and a higher SNR than the 5-channel coil in routine stress CMR.

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Correspondence to Thomas R Burchell.

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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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Burchell, T.R., Boubertakh, R., Mohiddin, S.A. et al. Further refining stress perfusion imaging: the initial clinical impact of a 32 channel surface coil. J Cardiovasc Magn Reson 12, P224 (2010). https://doi.org/10.1186/1532-429X-12-S1-P224

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Keywords

  • Cardiac Magnetic Resonance
  • Short Axis Slice
  • Peak Heart Rate
  • Image Quality Score
  • Stress Perfusion Imaging