Objective To investigate the diagnostic value of subtraction technique based coronary CT fractional flow reserve(CT-FFR)in detecting calcification-related hemodynamically signifi-cant stenosis.Methods A total of 22 patients(42 lesions)with known or suspected coronary ar-tery disease admitted in our hospital from March 2020 to March 2022 were recruited prospectively.Subtraction coronary computed tomography angiography(CCTA)was provided for the patients who were scheduled for invasive coronary angiography(ICA).CCTA image reconstruction algo-rithm was based on hybrid iterative reconstruction.FFR was detected in the patients with moder-ate-to-severe coronary stenosis caused by calcification.A FFR value ≤0.80 was defined as signifi-cant hemodynamic stenosis.With FFR as the reference standard,the diagnostic performance of CCTA,subtraction CCTA,CT-FFR,and subtraction CT-FFR in detecting calcification-related hemodynamically significant stenosis were evaluated.Results Lesion-based analysis showed that subtraction CT-FFR yielded the highest diagnostic performance among four groups of images,with a sensitivity,specificity,positive predictive value,negative predictive value and accuracy of 100.0％,62.1％,54.2％,100.0％and 73.8％,respectively,and an AUC value of 0.83.Patient-based analysis showed subtraction CT-FFR performed best in diagnostic performance,with a sensitivity,specificity,positive predictive value,negative predictive value and accuracy of 100.0％,33.3％,55.6％,100.0％and 63.6％,respectively,and an AUC value of 0.77.Conclusion Subtraction CT-FFR has the highest diagnostic performance for calcification-related hemodynamically signifi-cant stenosis,which expands the application of CT-FFR in severe calcification lesions,and is of good value in clinical application.