The Feasibility Analysis Of Connecting Attenuation Correction Of Myocardial Perfusion By Coronary Calcium Score Scan During Normal Expiration Obtained By The Same SPECT/CT

The basic process of coronary artery disease（CAD）is hemodynamic caused by functional or organic changes of coronary arteries,resulting in myocardial ischemia,hypoxia,or necrosis.The morbidity and mortality of CAD have been risen significantly in the past decade.In the three national health surveys conducted by the National Health Commission in 2003,2008 and 2013,the prevalence of CAD in China was 4.6‰,7.7‰and 10.2‰.Therefore,early diagnosis,early intervention and accurate prognosis of CAD have great significance.Coronary artery stenosis caused by coronary atherosclerotic（AS）plaque is the main etiology of CAD,the AS begins with coronary artery vascular endothelial cell damage,and then,apolipoprotein B resides under the endothelium,which becomes the formation of damage-related molecular morphology,and then,the smooth muscle cells and vascular endothelial cells of adjacent tissue become activated,eventually leading to lipid accumulation under the endometrium of vessels.With the development of coronary atherosclerosis,it will gradually form calcification,which mediated by calcium,calcium can cause vascular smooth muscle cell proliferation,migration and intimal thickening.In the past,the passive deposition of calcium crystals in damaged tissues resulted in the calcification of atherosclerotic plaques.Recent studies have found that the calcification of AS plaques is a actively regulated process that is similar to bone formation which requires multiple factors to participate in.Currently,the most widely used examination in the diagnosis and treatment of coronary heart disease consist:traditional risk factor assessment,treadmill exercise test（TET）,echocardiography,coronary angiography（CAG）,coronary artery computed tomography Computed tomography coronary angiography（CTCA）,Coronary artery calcium score（CACS）,and myocardial perfusion imaging（MPI）,these techniques can evaluate CAD from different ways,but these techniques have their own defects and deficiencies.In clinical practice,there will be their own inevitable limitations using either techniques alone.Recently,the value of MPI combined with CACS in the diagnosis and treatment of CAD has become a hotspot.Researches at home and abroad show that MPI combined with CACS can improve the diagnostic accuracy of CAD,provide more accurate risk stratification and prediction of prognosis for CAD patients.SPECT/CT routinely runs a low-resolution computed tomography（LRCT）during MPI acquisition.The impact of photon attenuation due to respiratory motion and uneven soft tissue can be reduced and improve diagnostic accuracy and quantitative data accuracy of MPI by connecting the attenuation correction.With the development of technology,people wonder whether the attenuation correction could be performed with gated breath-hold calcification score（CACS）scan data.CT data obtained from SPECT/CT-matched low-speed CT can represent the average state of respiratory motion.,but the data obtained from multiple rows of high-speed CT represent a certain stage of breath-hold.Since respiratory motion affects attenuation correction,this limits the use of CACS as attenuation correction.Some studies have shown that the maximum end-expiratory breath hold is close to the state of free breathing.This study mainly explored the feasibility of CACS(CACS_EXP)CT with end-expiratory breath held for MPI attenuation correction.ObjectiveTo investigate whether the coronary calcium scoring scan during normal expiration（CACSEXP）can use for attenuation correction of SPECT myocardial perfusion imaging（MPI）.Materials and MethodsThe 31 patients with suspected or diagnosed CAD who underwent MPI and CACS_EXP scan by SPECT/CT during October 2016 to July 2017 were prospectively studied.AC of the iteratively reconstructed images was performed by the low-resolution X-ray CT（LRCT）facility attached to MPI and CACS_EXP.Automatically determined uptake values of stress scans（QPS,Cedars Medical Sinai）from CACSEXP were compared with IRAC.The MPI image was read and scored by two experienced nuclear medicine physicians,the summed stress score（SRS）were also compared.ResultsThere was no significant difference between EX%obtained by CACS_EXP（4.55±6.51）and EX%（3.81±7.42）obtained by LRCT（P>0.05）;There was no significant difference between TPD obtained by CACSEXP（4.55±6.51）and TPD（3.81±7.42）obtained by LRCT（P>0.05）.Compared the results of the two images,there was no significant difference between SRS（2.40±4.04）and SRS（2.40±4.01）P>0.05;The SRS of each vascular distribution area were compared,the statistical data are as follows:left anterior descending,P=0.281;circumflex,P=0.180;right coronary artery,P=0.665,P>0.05.ConclusionCACS_EXP can be used for AC of MPI.Applying this to practice,patients can get coronary artery calcification scores while performing AC of MPI;reducing the patient’s radiation dose while providing more information for clinical.