Affiliation:
1. School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine King's College London London UK
2. MR Research Collaborations Siemens Healthcare Limited Newton House, Sir William Siemens Square, Frimley, Camberley Surrey UK
3. Department of Paediatric Cardiology Evelina London Children's Hospital London UK
Abstract
PurposeTo develop a motion‐robust reconstruction technique for free‐breathing cine imaging with multiple averages.MethodRetrospective motion correction through multiple average k‐space data elimination (REMAKE) was developed using iterative removal of k‐space segments (from individual k‐space samples) that contribute most to motion corruption while combining any remaining segments across multiple signal averages. A variant of REMAKE, termed REMAKE+, was developed to address any losses in SNR due to k‐space information removal. With REMAKE+, multiple reconstructions using different initial conditions were performed, co‐registered, and averaged. Both techniques were validated against clinical “standard” signal averaging reconstruction in a static phantom (with simulated motion) and 15 patients undergoing free‐breathing cine imaging with multiple averages. Quantitative analysis of myocardial sharpness, blood/myocardial SNR, myocardial‐blood contrast‐to‐noise ratio (CNR), as well as subjective assessment of image quality and rate of diagnostic quality images were performed.ResultsIn phantom, motion artifacts using “standard” (RMS error [RMSE]: 2.2 ± 0.5) were substantially reduced using REMAKE/REMAKE+ (RMSE: 1.5 ± 0.4/1.0 ± 0.4, p < 0.01). In patients, REMAKE/REMAKE+ led to higher myocardial sharpness (0.79 ± 0.09/0.79 ± 0.1 vs. 0.74 ± 0.12 for “standard”, p = 0.004/0.04), higher image quality (1.8 ± 0.2/1.9 ± 0.2 vs. 1.6 ± 0.4 for “standard”, p = 0.02/0.008), and a higher rate of diagnostic quality images (99%/100% vs. 94% for “standard”). Blood/myocardial SNR for “standard” (94 ± 30/33 ± 10) was higher vs. REMAKE (80 ± 25/28 ± 8, p = 0.002/0.005) and tended to be lower vs. REMAKE+ (105 ± 33/36 ± 12, p = 0.02/0.06). Myocardial‐blood CNR for “standard” (61 ± 22) was higher vs. REMAKE (53 ± 19, p = 0.003) and lower vs. REMAKE+ (69 ± 24, p = 0.007).ConclusionsCompared to “standard” signal averaging reconstruction, REMAKE and REMAKE+ provide improved myocardial sharpness, image quality, and rate of diagnostic quality images.
Funder
British Heart Foundation
Engineering and Physical Sciences Research Council
King's College London
National Institute for Health Research
Siemens Healthineers
Subject
Radiology, Nuclear Medicine and imaging