Comparative evaluation of diaphragmatic and myocardial navigation in coronary magnetic resonance imaging

Coronary magnetic resonance angiography (CMRA) is limited by respiratory motion artifacts, for which diaphragmatic navigation (dNAV) is commonly applied. Myocardial navigation offers a direct motion-tracking alternative, but its performance in different anatomical placements remains underexplored. This study aimed to compare the image quality and clinical feasibility of diaphragmatic and myocardial navigation approaches at 3.0 T.

Thirty-three healthy volunteers underwent CMRA with four navigators: dNAV, left ventricle navigation (LvNAV), right atrial navigation (RaNAV), and apex navigation (ApNAV). Acquisition efficiency, scan duration, success rate, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were analyzed for major coronary segments: right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX). Two observers independently scored image clarity and sharpness (4-point scale) for segments. Interobserver agreement was assessed via intra-class correlation coefficient (ICC).

LvNAV and RaNAV both achieved a 100% technical completion rate (30/30). This was higher than the technical completion rates for ApNAV (97%, 29/30) and dNAV (90%, 27/30), with the latter two groups experiencing failures due to navigator drift. Scan durations showed no significant differences (dNAV: 478.70±104.68 s; LvNAV: 469.62±102.64 s; P=0.332). LvNAV yielded the highest SNR and CNR (P<0.05). Proximal and mid segments of the RCA, LAD, and LCX showed comparable visualization between dNAV and LvNAV (P>0.05), whereas distal segment visibility was reduced mainly with RaNAV and ApNAV, with dNAV and LvNAV preserving better distal visualization. Coronary visualization rates differed significantly (χ²=76.563, P<0.001), with dNAV and LvNAV outperforming other techniques.

Myocardial navigation, particularly LvNAV, yields superior image quality and visualization performance comparable to dNAV, representing a promising alternative under conditions requiring enhanced motion stability. Personalized navigator selection based on respiratory patterns may further optimize CMRA outcomes.