An accurate, robust, and computationally efficient navigator algorithm for measuring diaphragm positions

Purpose: The purpose of this study is to develop an improved algorithm for measuring the position of the diaphragm using navigator echoes. Method: This algorithm was applied to navigator echo data acquired from 14 cardiac patients. For each patient, 160 navigator echo profiles were acquired across the right hemi-diaphragm along the superior-inferior direction. Results: The accuracy of the proposed edge-detection algorithm was evaluated together with that of the least-squares and linear phase-shift algorithms. The estimated measurement error of the proposed algorithm was approximately two times smaller than that of the least-squares algorithm (Magn Reson Med, 1996:36: 117-123), and was approximately four times smaller than that of the linear phase-shift algorithm (Magn Reson Med, 1999;42:548-553). The computational efficiency of this algorithm was 7.5 times higher than that of the least-squares algorithm and was comparable with that of the linear phase-shift algorithm. Conclusion: The presented algorithm is accurate, robust, and computationally efficient in the measurement of the diaphragm position.