New catheter-based calibration method for 2D X-ray angiography myocardial perfusion

Assessment of myocardial perfusion in 2D X-ray angiography image during coronary interventional treatment is important for better patient outcome. It is necessary for 2D image signal intensity to lineally relate with amount of contrast agent in body for quantitative perfusion analysis. However, it is not linear because of scatter and beam hardening. The aim of this study is to propose simple and practical calibration method for linear relationship. The image signal intensity of the catheter is used to estimate scatter ratio and patient body thickness, and to generate correction function. This correction function is applied to all 2D image pixels to generate corrected image. For verification, 370 mg/ml iodine contrast agent in a 2-mm-diameter silicone tube was used, and correction function was generated. The generated correction function was used to correct image signal intensity of 15 different amount of contrast agent. The corrected image signal intensity were compared with the actual. The mean error between the actual and estimated value was 4.8%. The linear regression line slope was 0.97 and correlation coefficient was R=0.998. The proposed method was confirmed to achieve a good linear relationship between 2D image signal intensity and amount of contrast agent in body.