Ian Marshall, Maurits A Jansen, Yuehui Tao,

Gavin D Merrifield, Gillian A Gray

University of Edinburgh

Accelerated mouse cardiac imaging using threefold undersampling and kt-BLAST reconstruction

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Computer 35

Introduction

Mouse kt-BLAST cardiac imaging 3847

Why acceleration?

- shorter scan times, reduced costs,

- improved patient compliance

- reduced animal burden

Parallel imaging now widely used clinically

(some) kt-undersampling for human cardiac scanning

Limited translation of techniques to rodent imaging

- would improve animal welfare (3Rs)

Study design

6 healthy + 2 MI adult mice

Cardiac MRI scans in short-axis plane

Standard CINE sequence

3-fold accelerated ktBLAST sequence + training data

Comparison of image quality and cardiac indices

EDV, ESV, EF, EDM, ESM

Mouse kt-BLAST cardiac imaging 3847

Scanning details

7T scanner (Agilent Technologies)

39 mm quad coil

Respiratory gating and cardiac triggering

CINE Gradient Echo sequence

- (12 frames, 192×192, FOV 30 mm, 3 Averages)

kt-BLAST sequence (Tsao MRM 2003)

- 3× undersampling (linear grid)

- 16 central training rows

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Image analysis

One analyst, blinded to type of images

Subjective quality (scale 1-5)

Endo- and epicardial borders drawn manually

Cardiological indices derived

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Images

fully sampled 3× undersampled

Mouse kt-BLAST cardiac imaging 3847

“Ratios”

Mouse kt-BLAST cardiac imaging 3847

• =MI

Bland-Altman plot

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EDV

MI MI

Results summary

Cardiological indices (σ) wrt fully sampled images

“Ratios” Bland-Altman bias

EDV 0.94 (0.07) -5 (8) μL

ESV 1.06 (0.14) 2 (6) μL

EF 0.93 (0.08) -5 (5) %

EDM 1.11 (0.10) 13 (12) mg

ESM 1.01 (0.06) 1 (8) mg

Image quality: 4.3±1.2 (full) versus 3.8±1.4 (ktBLAST)

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Discussion

kt-BLAST images have similar “quality”

“Ratios” biased up to 11% (for EDM)

- corresponding Bland-Altman bias 13 mg

Observer variability 3-10% (Heijman JMRI 2008)

MI mice (large hearts and small EF)

Overall acceleration 2.4×

Compare with Compressed Sensing (Wech JMRI 2011)

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Conclusion

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Accelerated cardiac imaging of mice is feasible

Threefold acceleration gives acceptable results

This enables- increased throughput- improved animal welfare

AcknowledgementsPeter HoskinsTom AndersonSteven FortuneMike DaviesGabriel RillingRoss LennenAgnieszka Kozak

Mouse kt-BLAST cardiac imaging 3847