Construction of a Diaphragmatic Function Map from a 4D Magnetic Resonance Image Using the Intersection Profile Method

Abstract

Purpose: To evaluate diaphragmatic motion quantitatively, we constructed a diaphragmatic function map using a four-dimensional magnetic resonance image (4D-MRI) reconstructed using the intersection profile method. Methods and Materials: Six subjects (three healthy subjects and three patients with pulmonary disease) were examined during spontaneous breathing. A clinical MRI system (1.5T Intera Achieva Novadual; Philips) was employed, and the intersection profile method was used to reconstruct the 4D-MRI. The contours of the diaphragm were extracted from the 4D-MRI using a semiautomatic technique. These results were used to calculate the amount and speed of vertical displacement of the diaphragm. The two derived parameters were displayed as false-color maps called the "diaphragm displacement map" and the "diaphragm speed map". Results: The diaphragm displacement map showed that movement of the dorsal portion of the diaphragm was greater than that of the ventral portion of the diaphragm in the three healthy subjects. The distribution of diaphragmatic displacement in the patients with pulmonary disease differed from that in the healthy subjects. The diaphragm speed map showed paradoxical diaphragmatic motion in one patient. Conclusion: The proposed method is able to visualize diaphragmatic function during spontaneous breathing and may prove useful for the investigation of normal and abnormal respiratory mechanics.