Abstract
BACKGROUND: Four-dimensional flow cardiac magnetic resonance (4D flow CMR) continues to predominantly utilize conventional diaphragmatic navigation, despite its inherent limitations of prolonged acquisition times and suboptimal image quality. Targeted respiratory regulation enhances participant stability during imaging, while precision diaphragm localization-implemented through the balanced steady-state free precession (bSSFP) sequence-delivers superior localization accuracy. The integration of these techniques may reduce scan time and improve image quality. However, the impact of targeted respiratory regulation and precision diaphragm localization on 4D flow CMR has not been systematically investigated. This study evaluates an improved diaphragmatic navigation approach that combines these methodologies, providing a direct comparison with conventional diaphragmatic navigation for 4D flow CMR applications. METHODS: This prospective study enrolled 55 participants, including 38 hypertrophic obstructive cardiomyopathy (HOCM) patients and 17 healthy volunteers. Each participant underwent two 4D flow CMR scans: one using conventional diaphragmatic navigation (conventional method) and the other using improved diaphragmatic navigation (improved method). The paired sample t-tests analysis and the Wilcoxon signed-rank test were conducted to evaluate differences between the two methods in terms of (I) factors related to acquisition time (including navigation offset, actual scan time, and acquisition efficiency); (II) image quality [including apparent signal-to-noise ratio (aSNR), visibility, and artifacts (scored 1-4, with 1 indicating severe artifacts and 4 minimal artifacts)]; and (III) confidence in hemodynamic diagnostic assessments. RESULTS: The study included 55 participants (23 male; mean age 47.91±15.26 years) who underwent two 4D flow CMR scans, yielding 110 complete datasets. The improved method demonstrated significant advantages over conventional navigation across in the factors related to acquisition time: navigation offset decreased from 14.85±6.97 to 3.35±2.34 mm (P<0.001), actual scan time reduced from 538.89±187.30 to 422.55±88.34 s (P<0.001), and acquisition efficiency improved from 49.71%±10.72% to 60.15%±5.46% (P<0.001). Image quality metrics revealed comparable aSNR (conventional: 10.66±3.60 vs. improved: 10.44±3.24, P=0.59) and visibility scores {3 [interquartile range (IQR), 3-4] for both, P=0.15}, but significantly fewer artifacts with the improved method {conventional: 2 [1-2] vs. improved: 2 [2-3], P<0.001}. Both methods provided equivalent confidence levels for hemodynamic assessments (all P>0.05). CONCLUSIONS: Compared to conventional diaphragmatic navigation used in 4D flow CMR, the improved method reduces examination time and enhances image quality, and it has the potential to improve the efficiency of Guangdong Provincial People's Hospital in the diagnosis of cardiovascular diseases.