A Preliminary Study Of The Value Of Iterative Model Reconstruction Technique Combined With Low-dose Coronary CTA In Diagnosis Of Coronary Artery Stenosis

Objects: To evaluate the quality of low-dose coronary CT combined with Iterative Model Reconstruction in coronary arteries and the catheter coronary angiography as control,to evaluate the diagnostic efficacy of low-dose CT combined with IMR in diagnosis of coronary artery stenosis.Methods: We retrospective analysis 80 patients suspected coronary heart disease in our hospital from January 2016 to July 2017 who underwent coronary CTA and the catheter coronary angiography(CAG).Coronary CTA used a low-tube-voltage 100 k V prospective ECG-gated scan and Iterative Model Reconstruction for image reconstruction.The image quality of coronary vessels were divided into 4 grades(4 to 1 for excellent,good,qualified and non-evaluable),and two experienced physicians independently assessed the subjective scores of each vessel of coronary arteries.Kappa test was used to evaluate the difference in subjective score between two physicians.Coronary angiography showing coronary artery luminal diameter reduction> 50% as stenosis positive standard,the sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV)and accuracy of coronary CT in the diagnosis of coronary artery stenosis were calculated on segment-and vessel-based levels.Patients were further divided into two groups according to the Agaston score(group A <400,group B≥400).The differences in diagnostic performance between the two groups were tested.Results: Two physicians had a good agreement with the subjective coronary score(kappa=0.874).Diagnostic image quality was found in 96.6%(309/320)at the level of vessels(2 points and above).Among them,there were 117 vessels with positive CT diagnosis and 123 vessels with coronary artery stenosis confirmed by angiography.The sensitivity,specificity,PPV,NPV and accuracy of CT in the diagnosis of coronary artery stenosis were 84.6%,93.0%,88.9%,90.1% and 89.6%,respectively.Diagnostic image quality was found in 98.1%(785/800)at the level of segments.Among them,there were 149 segments with positive CT diagnosis and 146 segments with coronary artery stenosis confirmed by angiography.The sensitivity,specificity,PPV,NPV and accuracy of CT in diagnosing coronary artery stenosis were 93.2% 98%,91.3%,98.4% and 97.1% respectively.There was a significant difference in specificity,PPV and accuracy between groups A and B(99.2% & 91.8%,95.7% & 84.2%,97.9% & 93.7%,P <0.05;segment-based).The average effective dose was 1.49 ± 0.54 m Sv.Conclusions: Low-dose coronary CT combined with IMR can achieve satisfactory image quality and high diagnostic accuracy for coronary artery stenosis.However,the diagnosis of severely calcified segments is still limited.