Frequency-Tunable Imaging: software visualization of lung function and pulmonary blood flow using Cine chest X-ray without contrast media

Abstract

Abstract Purpose To show the method that visualizes signal fluctuations related with respiration or pulmonary blood flow using cine chest X-ray imaging without contrast media. Materials and Methods Cine chest radiographs were obtained from a healthy volunteer using angiography. The exam was performed at the supine position with a distance of 0.88 m, 15 frames/second. The lung fields were defined in all frames using Bézier curves and subdivided into small blocks. The respiratory rate (RR) was calculated from the movement of the diaphragm, and the heart rate (HR) was calculated from the differences of the pixel value of the heart area. In each block of the lung fields, the differences of the pixel value were calculated, and signals were synthesized by Inverse Fourier Transform with selected frequency components corresponding to the RR and HR. Results A total of 198 frames were acquired and 165 were subsequently analyzed. The estimated total dose was 0.2 mGy. RR and HR are calculated as 15–21 breaths per minute (brpm) and 79–85 beats per minute (bepm), which are equivalent to measured values (16 brpm and 80 bepm, respectively). Then, signal fluctuations related with the RR and HR were visualized as movies. Signal patterns were compatible with the features of respiratory dynamics or pulmonary perfusion dynamics. Conclusion Our technique visualized signal fluctuations related with respiration or pulmonary blood flow. Obtained signal patterns were compatible with respiratory dynamics or pulmonary perfusion dynamics.