| PART 1 THE STUDY OF BEAM-HARDENING CORRECTION BY MONOCHROMATIC IMAGING VIA DUAL-ENERGY MYOCARDIAL PERFUSING IMAGING WITH DUAL-SOURCE CTBackground:Dual-energy computed tomography (DECT) imaging is gradually applied in clinical.But due to factors such as contrast medium concentration, uniformity of the organization,often appear special beam hardening artifacts. In dual-energy CT myocardial perfusion imaging, the accuracy in diagnosis often reduces because of the morphological characteristics of beam hardening artifacts are like ischemic myocardial perfusion defect.Therefore, before the application of dual-energy CT myocardial perfusion scanning,we should optimize the scanning solutions. Domestic and foreign researches show that different tissues all have their own characteristic kilo-eletron-volt(keV) X-ray.Image shows good quality after absorption of characteristic keV X-ray on CT images,and corrects beam hardening artifacts to a minimum at the same time. Based on the above theory,this part intends to finish parameters optimization experiment of dual-energy CT myocardial perfusion imaging.Objective:To observe the high incidence site of beam hardening artifacts in dual-energy CT myocardial perfusion imaging,and compare the image quality and effcet for beam hardening correcting of different monochromatic energe imaging via dual-energy myocardial perfusing imaging with dual-source CT.Methods:84 patients requiring cardiac enhancement-CT examination were underwent dual-energy (100/Sn140kVp) myocardial perfusing imaging with dual-source CT from Oct.2013 to Mar.2014 who were suspected or diagnosed coronary artery disease enrolled. Apllicating Dual-energy Monoenergy post-processing software with results of iodine maps and. monochromatic images under 65keV,75keV,85keV,95keV,105keV.Counting the number of beam hardening artifacts with control of M image (weighted polychromatic 120kV) which is automated system generation,measuring artifacts iodine content,CT value.. Comprehensively evaluating the value of monochromatic imaging after dual-energy myocardial perfusion imaging according to the correction of artifacts,signal-to-noise ratio(SNR), contrast to noise ratio(CNR) and subjective image quality grades.Results:The artifacts number:274 (65keV)>246 (75keV)>235 (105keV)>225 (120kV)>211 (95keV)>207 (85keV) (F=21.56,p<0.05).The high incidence site of artifacts was the left ventricular basal segment 36.5%(100/274), the next was ventricular septal segment 25.91%(71/274)?Superior-vena-cava-besides segment 24.82% (68/274)?posterior segment 12.77%(35/274) (p<0.05); iodine content of myocardiaum:under artifacts (-2.37±0.84) mgI/g<non-under artifacts (3.5±0.92) mgl/g (t=-19.36,p=0.000). Non-artfact myocardial CT value of 85keV (93.52±18.52) HU is the closest to polychromatic 120kV (96.06±16.32) HU,with significant statistic differences of CT value between the two groups (p=0.000); SD of 85keV (12.98±3.16) is the lowest (p=0.000),SNR of non-artifact myocardial:75keV (6.89±1.79) and 85keV (6.5±1.7) are higher, with no statistic differences between the two groups (t=1.5,p=0.14), CNR:75keV(18.79±6.76)is highest (p=0.000), and there is no statistic differences between 85keV (15.4±5.67) and 65keV (15.53±4.56) (t=0.27,p=0.79);The 85keV images get the highest image quality scores.The evaluation for image quality of the two radiologists is highly consistent(Kappa=0.79,p<0.05).Conclusion:The left ventricular basal segment?ventricular septal segment and superior-vena-cava-besides segment are frequently affected region of beam-hardening artifacts in turn;Myocardial density of 85keV is closest to polychromatic 120kV image,but 85keV can most effectively correct beam-hardening artifacts with better image quality.PART 2 THE CORRELATION STUDY OF CORONARY ARTERY TORTUOSITY AND MYOCARDIAL IODINE CONTENT WITH DUAL-ENERGY CT MYOCARDIAL PERFUSION IMAGINGBackground:DSA, CTA and other domestic or foreign imaging studies show that coronary artery toutuosity is common among patients who complained about precordial distress. Which are often characterized by S-T stretch, decreased left ventricular cardiac function in Holter and echocardiography. Above characteristics of all patients with coronary artery toutuosity, prompt there may be inadequate myocardial blood flow. Dual-energy CT can complete coronary CTA and myocardial perfusion imaging at the same time,and post-processing generated respectively the distribution of iodine map and myocardial iodine content,which represent myocardial blood flow distribution and blood volume.The compliance rate compared with SPECT is high.This part proposed to study whether coronary artery tortuosity dominated myocardial ischemia on the basis of the optimizing scan parameters by analysising the relationship between coronary artery tortuosity degree and myocardium iodine distribution.Objective:To investigate the correlation between coronary tortuosity and myocardial iodine content by dual-energy CT myocardial perfusion imaging.Methods:98 patients (male 48/female 50) who complained about precordial distress were carried out dual-energy CT myocardial perfusion imaging continuously from Mar.2014to Nov.2014.Polytype reconstruction images of coronary artery CT angiography?iodine distribution color map of myocardium and greyscale map of polychromatic energy 120kV were obtained by post-processing workstation. Counting the number of tortuous segments and tortuousity index(TI) of coronary arteries.Myocardial iodine content and CT value were measured at 15 coronary artery segments and 17 myocardical segments by criterion. The difference of myocardial iodine content between coronary artery tortuosity group and non-tortuosity group was compared, and the correlation of coronary artery tortuosity and myocardial iodine content was analysed..Results:Tortuousity group included 58 cases,of which502 segments were tortuous vessels.93.23% of tortuous vessels were no stenosis.The distribution ratios of tortuous vessels:60.96% occurred in left anterior descending branch or diagonal branch,23.5%were in circumflex branch,and another 15.6% were in right coronary branch.The tortuousity number was 1104,and mean tortuous angle was (109.08±20.9)°,while another 40 cases composed non-tortuousity group.The mean TI of tortuousity group (1.51±0.14) was larger than non-tortuousity group(1.21±0.04),while myocardial iodine content and CT value of myocardium supplyed by tortuous coronary without stenosis (-1.04±0.38mg/ml,63.84±7.92HU) were both smaller than non-tortuousity group (4.52±0.21mg/ml,98.55±6.41HU).There were significant statistic differences of TI (t1),iodine content (t2) and CT value (t3) between the two groups (t1=23.1,t2=-3.03,t3=7.28,p=0.000).The correlation between myocardial iodine content and TI of coronary tortuosity was significant negative (R=-0.86,p=0.000).96.55%(X12) and 82.76%(X22) patients in tortuous group respectively complained about angina after exercise and S-T segments abnormal in electrocardiogram, while 72.41%(X23) were left ventricle dysfunction,which all were statistically significant different from non-tortuousity group (X12=20.47,X22=15.35,X22=15.32,p=0 .000).Conclusion:Coronary tortuousity often occurs in left anterior descending branch,while less stenosis merged existed; Tortuosity of non-stenosis coronary artery is negative related to the mycardial iodine content.PART 3 COMPARATIVE STUDY OF TORTUOUS CORONARY ARTERY DSA AND ITS SPECT MYOCARDIAL PERFUSION IMAGINGBackground:Coronary artery angiograph has been recognized as the gold standard in diagnosising coronary heart disease, and SPECT radionuclide myocardial perfusion imaging is the gold standard for diagnosising myocardial ischemia. There have been many studies domestic or forgien combined the two methods to study the myocardial ischemia of coronary artery stenosis, the diagnostic accurate rate> 90%. This part proposed to combine the two methods to study the correlation between coronary artery tortuosity without stenosis and.myocardial ischemia.Objective:To study the correlation of myocardial ischemia and coronary artery tortuosity through DSA combining SPECT.Methods:Retrospectively analysis the images of 17 patients (9 male/ female 8) who completed DSA and SPECT myocardial perfusion imaging from 2010 to 2013 during half year,mean interval time between two kinds of examination was (0.97±0.06) months. Coronary artery are divided into 15 segments,and the myocardial is divided into 17 segments..Calculate the tortuosity index (TI=L tortuous/L straight). Count the number of perfusion defect, tortuousity number, and measuring tortuous angles.The relevance of tortuous coronary without stenosis and myocardial ischemia according to the anatomical relationships of blood vessel and myocardium supplied were analysed.Results:Myocardial perfusion reduced presence in 36 segment of 17 patients, of which 94.44% were supplied blood by tortuous coronary arteries.Total 71 tortuous vessels,which 53.52% occurred in left anterior decending branch,28.17% in left circumflex branch,and another 18.31% were in right coronary artery.The tortuosity number of coronary arteries is 293,and the average tortuous angle is (113.5±17.1)°,TI=1.42± 0.27.non-tortuous coronary arteries take shape naturally, tortuous average angle (172.71±8.7)°, TI=1.18±0.01. Tortuosity angle(t1) and TI(t2) between tortuous vessels and non-tortuous vessels were statistically different(t1=12.44,t2=7.57,p<0.05).Tortuous angle, TI and perfusion defect stove correlation coefficients were R1=0.70,R2=0.79 (t1=0.21,t2=0.34, p<0.05).Conclusion:The myocardial dominated by tortuous coronary artery may present ischemia... |
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