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. METHODS 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.

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