Free-breathing delayed hyperenhanced imaging of the myocardium: a clinical application of real-time navigator echo imaging.

Purpose: To compare a free-breathing (FB) acquisition with the current standard of breath-holding (BH) in a clinical setting using identical two-dimensional MR pulse, sequences for imaging of myocardial delayed hyperenhancement. Materials and Methods: Two-dimensional gadolinium enhanced images were acquired using FB and BH techniques in 18 subjects to evaluate delayed enhancement of myocardial infarction. The FB acquisition used a navigator echo to monitor the position of the right hemidiaphragm for respiratory gating and correction. Visual analysis using a 16-segment model, quantitative signal difference to noise ratios, and percent left ventricle (LV) viability measurements for the two acquisition types were statistically compared. Results: An excellent agreement between two-dimensional BH and two-dimensional FB acquisitions was found. In one patient, a nontransmural infarct was seen only in the FB images. There were no statistically significant differences in the number of infarcted segments or the measured signal. difference to noise ratios (SDNR) between the two methods. Linear regression and Bland Altman analysis of the percentage LV viable myocardium yielded a good fit and narrow limits of agreement. Conclusion: An FB navigator echo acquisition can be effectively used in the setting of myocardial delay hyperenhanced imaging. Image quality is similar or superior to that of BH imaging.