Motion compensated cine CMR of the fetal heart using radial undersampling and compressed sensing.
BACKGROUND
To develop and evaluate a reconstruction framework for high resolution time-resolved CMR of the fetal heart in the presence of motion.


METHODS
Data were acquired using a golden angle radial trajectory in seven fetal subjects and reconstructed as real-time images to detect fetal movement. Data acquired during through-plane motion were discarded whereas in-plane motion was corrected. A fetal cardiac gating signal was extracted to sort the corrected data by cardiac phase, allowing reconstruction of cine images. The quality of motion corrected images and the effect of data undersampling were quantified using separate expressions for spatial blur and image error.


RESULTS
Motion corrected reordered cine reconstructions (127 slices) showed improved image quality relative to both uncorrected cines and corresponding real-time images across a range of root-mean-squared (RMS) displacements (0.3-3.7 mm) and fetal heart rates (119-176 bpm). The relative spatial blur between cines with and without motion correction increased with in-plane RMS displacement leading to an effective decrease in the effective spatial resolution for images without motion correction. Image error between undersampled and reference images was less than 10% for reconstructions using 750 or more spokes, yielding a minimum acceptable scan time of approximately 4 s/slice during quiescent through plane motion.


CONCLUSIONS
By rejecting data corrupted by through-plane motion, and correcting data corrupted by in-plane translation, the proposed reconstruction framework accounts for common sources of motion artifact (gross fetal movement, maternal respiration, fetal cardiac contraction) to produce high quality images of the fetal heart.
Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.|Division of Physiology and Experimental Medicine, The Hospital for Sick Children, Toronto, ON, Canada.
Christopher W
http://orcid.org/0000-0002-3111-8840
CW
Roy
Division of Pediatric Cardiology, The Hospital for Sick Children, Toronto, ON, Canada.|Departments of Pediatrics and Diagnostic Imaging, University of Toronto, Toronto, ON, Canada.
Mike
M
Seed
Department of Obstetrics and Gynaecology, Mount Sinai Hospital, Toronto, ON, Canada.|Department of Obstetrics and Gynaecology, University of Toronto, Toronto, ON, Canada.
John C
JC
Kingdom
Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada. christopher.macgowan@sickkids.ca.|Division of Physiology and Experimental Medicine, The Hospital for Sick Children, Toronto, ON, Canada. christopher.macgowan@sickkids.ca.
Christopher K
CK
Macgowan
D001696:Biomechanical Phenomena; D055424:Cardiac-Gated Imaging Techniques; D016022:Case-Control Studies; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005865:Gestational Age; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009200:Myocardial Contraction; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D013997:Time Factors
Accelerated imaging; Compressed sensing; Fetal CMR; Golden angle radial; Motion correction; Post-processing