| BackgroundWith the development of society economy and the global trend of population aging is gradually serious, the incidence of coronary heart disease and myocardial infarction increases rapidly; and then has become a serious hazard to human life safety health killer. According to the WHO published the "2011World Health Statistics", it pointed out each year because of heart disease, diabetes and cancer and other non-communicable diseases lead to deaths of about35000000people in the world, accounted for2/3of the total global death population; the deaths of coronary heart disease which occur in China has ranked second in the world. Therefore, early diagnosis, early treatment, can effectively reduce the incidence of coronary heart disease and reduce the mortality rate. Conventional coronary angiography is the main examination technique in the diagnosis and treatment of coronary artery disease, but it cannot directly detect myocardial microcirculation vascular injury and myocardial perfusion changes of microscopic lesions. Therefore, to improve the level of diagnosis and treatment of coronary heart disease, in addition to accurately judge the degree of coronary artery stenosis, whether there have concurrent myocardial infarction, and secondary myocardial morphological changes, still need to identify myocardial activity, grasp the change of cardiac function condition. Such for the choice of treatment, curative effect and prognosis are very important. Myocardial perfusion is currently the clinical evaluation of myocardial microcirculation function, the main method for identification the myocardial viability. When the normal function with the myocardial cells under a stressing, between myocardial perfusion, myocardial metabolism and myocardial contractile function can be keep the dynamic balance. But the ischemic heart disease would show the reduction of myocardial perfusion, and secondary imbalance among myocardial metabolism, function and perfusion. The CT myocardial perfusion compared to other imaging methods, it has an extremely high temporal resolution, and spatial resolution.It can be in a coronary artery CTA imaging simultaneously to gain the data about the evaluation of left ventricular function. Although MSCT myocardial perfusion has a good prospects for develop in evaluation of microcirculation in coronary heart disease and the myocardial activity identification, but it stills in the stage of clinical research, the lack of reference and standard, even many of the contradictions and disputes. This research attempts to use the320-row spiral CT myocardial perfusion imaging combined with the dobutamine stress test to study the feasibility about the integration of imaging methods of myocardial examination in one-stop and obtain the comprehensive information of heart. That is mean we can gain the coronary and heart function evaluation data within once heart scan, even on can make an identification between infarcted myocardium and myocardial viability, or make a quantitative analysis about the functional status of myocardial microcirculation to evaluated the state of myocardial activity base on the same data. And through the application of coronary heart disease myocardial ischemia, understanding the comprehensive application value of MSCT myocardial perfusion in ischemic myocardium of coronary heart disease.1Objective1.1To explore the feasibility about to obtained all cardiac imaging data in an examination of heart scan using the320-row spiral CT myocardial perfusion imaging combine with the myocardial stress test; that means not only can obtain the information of coronary anatomy, also can get the evaluative data of left ventricular function index, and can make a quantitative analysis the function of myocardial microcirculation.1.2To evaluate the value of320-row spiral CT myocardial perfusion imaging in myocardial ischemia of coronary heart disease.2Methods2.1clinical data24patients with coronary heart disease were collected in this research during Apr,2011to Dec,2011by using the320-row spiral CT myocardial perfusion scan, including13males,11females; aged from37to72years, median age of52.5±3.2years old. There were13cases of the normal group, including9males,4females; mean age43.7years. In24cases of coronary heart disease underwent radionuclide myocardial perfusion imaging confirmed myocardial segmental perfusion defect (both left ventricular wall perfusion defects), suggested the presence of reversible myocardial ischemia; of which16cases have typical angina symptoms,8cases of suspected chest discomfort. The criteria of the normal group was as follows:(1)no clinical symptoms with coronary heart disease and signs in past and at present;(2), no clinical symptoms and signs of hypertension;(3), no other congenital or acquired cardiac disorders;(4), no other lesions of cardiac function and conduction block related;(5), no history of drug allergy and heart lung and kidney function failure disease;(6),no abnormality of previous ECG examination;(7), indexes of cardiac physical examination are normal;(8),has no adverse reaction about drug (dobutamine) stressing.Among the myocardial ischemia of coronary heart disease group and the normal group, all subjects were without iodine contrast medium allergy history, without a beta blocker use of hypertension contraindication, no electric conduction disturbance, no dysfunction of cardiac or renal, the hypertension could be control, and the blood pressure<190/120mmHg in rest, no respiratory dyskinesia, consciousness sober could cooperate with the inspection carried out. All the subjects accepted education before the scan, made them to understand purpose and method of the test, and understand the adverse reaction and its corresponding treatment measures, and let all subjects signed the informed consent to confirm, informed consent content and format as shown in Tab1.1.2.2Preparation for the heart coronary artery CTA angiography and myocardial perfusion CT scan before.Before the examination subjects to fasting for4-6h,12hours before the examination no take caffeine or cola food, coronary heart disease subjects needed discontinuation of beta blockers before checking24h. To measured the heart rate before the scan, if the heart rate of subjects was higher than80/min, he must use the betaloc25-50mg, let the heart rate control within60～75/min range. To measure the basic blood pressure, weight, height of subject, and calculated the corresponding values of BMI (BMI is calculated by dividing weight in kilograms by height in meters squared), and set the values of tube voltage and tube current according to the corresponding value of BMI. All subjects were accepted the breath training before examination, try to ask the patient to keep breath with shallow slow and quiet during the whole test process, the subjects take the supine position, foot first, both arms held upward on the sides of head, connecting with the wire of electrocardiograph, at the same time in the subjects right arm elbow vein intravenous placed18G-20G trocar connection with high pressure twin injector.The left upper arm placed a blood pressure monitoring device, automatic measure the blood pressure, heart rate and mean pressure every interval30sec, set the heart rate≥150/min, or pressure≥190/120rnmHg as threshold, when the monitored value exceeds the standard, then display alarm.2.3The heart coronary artery imaging and myocardial perfusion scanning method.2.3.1The coronary artery CTA imaging and the method of myocardial perfusion CT rest scan.All examination were performed by using Toshiba Aquilion one320row dynamic volume CT, with prospective ECG triggering technology target interval scan mode (the general setting for heartbeat cycle75%), everything is ready for the double orientation image scanning, scan range from the tracheal bifurcation to heart under the diaphragm about1.5cm, breath-hold scan. Firstly, make a coronary artery calcification score scan, scan parameters:100kV tube voltage, tube current of300-450mAs/rot (specific values were setted according to the corresponding values of BMI and the sizes of subjects), thickness0.5mm, interval0.5mm, vision (FOV)180to220mm. Then the routine dose of breath-hold ECG gated dynamic volume scan mode continuous acquisition scanning, application of double tube injector through the right antecubital vein with5ml/s flow inject Ultravist (370mgI/ml)50～60ml (volume of injection according to the body mass index (BMI) of subjects), after injection use30ml saline with same rate to wash pipe, set the enhanced range consistent with the plain scan. The scan parameters:120kV tube voltage, tube current of350～450mAs/rot. Apply the Sure Star software of intelligent trigger scan system and select the thoracic aortic proximal as the region of interest detected the value of CT, when the density within the interest area reaches a preset value (in general set to180Hu), the coronary artery CTA imaging and rest myocardial perfusion scan will automatic start, synchronous electrocardiogram recording the scanning process. Set separately from myocardial perfusion scan startup time interval of10sec,20sec and30sec to make a delayed scan, with prospective ECG triggering technology target interval scanning heart, scanning parameters of100kV tube voltage, tube current of300-400mAs/rot.2.3.2The method of myocardial dobutamine stress test.Using20ml5%glucose inject diluted dobutamine hydrochloride injection20ml, micro pump was connected with the subjects left forearm venous catheter for infusion, starting the infusion rate was15μg/kg·min, for every3min increase rate5μg/kg·min, the maximum limit value setting30μg/kg·min; at the same time every1min blood start the pressure monitoring device, Closely observed the index changes of blood pressure and heart rate and the changes in the spirit and the symptoms of subject; when monitoring heart rate reaching target value of the test {0.85x(220-age)}; or the change of heart rate or blood pressure were too dramatically (such as heart rate≥130/min, systolic pressure≥200mmHg or the average variation amplitude of blood pressure≥20mmHg), if during the test subjects could not continue to load tolerance symptoms (such as:angina pectoris, arrhythmia, chest tightness, chest pain and discomfort or symptoms of dizziness, dry mouth, pale or weakness in the limbs) to terminate the stress test, the starting load of myocardial perfusion CT scan subsequent.2.3.3The method of myocardial perfusion CT scan with dobutamine stress.After the myocardial dobutamine stress test, start the myocardial perfusion scan was performed. Then the routine dose of breath-hold ECG gated dynamic volume scan mode continuous acquisition scanning, application of double tube inject or through the right antecubital vein with5ml/s flow inject Ultravist (370mgl/ml)30ml, after injection use30ml saline with same rate to wash pipe. Set the enhanced range consistent with rest scan. Apply the Sure Star software of intelligent trigger scan system and select the thoracic aortic proximal as the region of interest detected the value of CT, when the density within the interest area reached a preset value (in general set to180Hu),the dobutamine stressing scan will automatic start, synchronous electrocardiogram recording the scanning process. Set separately from myocardial perfusion scan startup time interval of lOsec,20sec and30sec to make a delayed scan, with prospective ECG triggering technology target interval scanning heart, scanning parameters of100kV tube voltage, tube current of300～350mAs/rot, the rest of the scanning parameters same as before.2.4The method of measured CT enhancement density using myocardial perfusion and the drawing method of myocardial time density curve.Browse the images showed in browse window of auxiliary machine workstation, the images were reconstructed in10heartbeat cycle by computer; selected the cardiac cycle least cardiac motion artifacts, used the multiple planar reconstruction software (MPR)to display the heart morphology in three-dimensional. For patients with coronary heart disease should be contrasted the abnormal area of myocardial perfusion showed by nuclide myocardial perfusion imaging. Selected the measured images of myocardial CT density values and placed a region of interest (ROI) in it. Respectively, measured and recorded the values of myocardial CT density at the scan time point of perfusion, delay10sec, delay20sec, delay30sec corresponding in rest state and after dobutamine stress-state. At the same time to adjust the image color, superposition pseudo color graph setting according to the CT values range in the heart image by3D plane display; in order to clearly identify the distribution of abnormal myocardial perfusion areas and its relative severity degree.In addition, according the measured values of myocardial CT density were respective gain from the scan time point at perfusion period, delay10sec, delay20sec,delay30sec corresponding in the rest and after dobutamine stress to outlining a time-density curves of myocardial. In the map the abscissa is scan time, the values of myocardial CT density as the ordinate. And then, make a comparsion myocardial time density curve corresponding in the rest and the dobutamine stress between normal group and myocardial ischemia of coronary heart disease group. To observed the differential change between normal myocardium and myocardial ischemia myocardium in different pathological state.2.5MSCT cardiac functional analysis and measuring methodTo collect the CT myocardial perfusion raw data of the rest and the stress, reconstructed to10groups of the cardiac cycle data by1.0mm thickness,0.5mm overlap, interval of10%.Input the two groups of reconstruct data into the Toshiba Vitreal2workstation, respectively. Apply the Cardial Functional CT package to get the image of left ventricular long axis and short axis in MPR, and choose the widest long axis of left ventricular cavity to adjust the apex direction. So that the apical of left ventricular and its long axis are on the same line, the computer outlining contours line of endocardium and epicardium automatically. And then, through the manual method, we can adjusted each phases contours of endocardium and epicardium in the left ventricular (interventricular septum and papillary muscles are not included within the calculation). By observing each periods, we take the minimum left ventricular cavity area as the end-systolic phase, and the largest area as the end-diastolic phase.Then through input height, weight, heart rate of the subjects, the values would be automatically calculated by computer according to the Simpson formula, including the end-diastolic volume of left ventricular(end-diastolic volume,EDV), the end-systolic volume(end-systolic volume, ESV), the stroke volume (stroke volume SV)(SV=EDV-ESV) and the values of ejection fraction [(ejection fraction, EF) EF=(EDV-ESV)/EDV] and so on, and then recording and analyzing the above datas statistically.2.6The transmural perfusion ratio(TPR) measurement in rest and after dobutamine stress by MSCT myocardial perfusion and the corresponding evaluation methods in coronary artery lesions.In the image browser windows of vice workstations browse the images, which were reconstruct into10phases of cardiac cycle images automatically by the computer workstation; selected the phase of cardiac cycle which had the least motion artifacts. Also exclude the presence of motion and beam hardening artifact. In the Clincal Tools interface of vice workstation start the myocardial perfusion reprocessing software--"Myocardial Analysis application", and import the selected the cardiac cycle phase data into rest and stress data analysis option,respectively; in the rest and the stress image management window setting the region of interest about left ventricular, respectively(Set LV ROI)(as shown Fig3-1). Then adjust the image so that the left ventricular maximum section can correspond exactly with cardiac short axis, vertical long axis and the horizontal axis direction, Ensure that the sense of left ventricular region of interest can include the whole of rest and stress; and then by computer automatic outlining the left ventricular inner wall and outer wall contour line (the inner wall contour line is green,the outer wall contour line is red). Through the manual mode, we adjust the contour line of inner wall and outer wall of left ventricular, ensuring the region of left ventricular myocardium wall which required to be analysed within the sampling range. And the subendocardial papillary muscle is not within the inner wall, and does not include the left ventricular outflow tract; confirming the range of left ventricular myocardial wall have been incorporated into the calculation and analysis (determine the data analysis where to start, where to end). Finally, import the selected cardiac cycle data of myocardial perfusion into the computer and make a analysis automatically, then it will calculate the TPR(transmural perfusion ratio, TPR) values of each myocardial segments in the left ventricular wall, and adjust the pseudo color graph of the myocardial perfusion, choose the black and white gray scale to display, and then setting the basic threshold in the Basic Value (HU) by manual, which is basic density value of the myocardium before strengthen.Left ventricular wall segments divided is refer to the standards of the American Heart Association ACC/AHA, the left ventricle is divided into vertical ventricular long axis of the basal, middle and apical three portions of16segment display (apical segments can be divided into seventeenth sections, but generally not included in the data analysis), the base is from mitral extending to the end-diastolic papillary muscle tip, display the bull’s-eye outer ring, include6muscle segments:S1(anterior basal segment),S2(anterior-septal basal segment),S3(down-septal basal segment), S4(down basal segment),S5(down-side basal segment),S6(anterior-side basal segment); middle ring including overall length of papillary muscle, which comprises of6muscle segments:S7(anterior-middle middle segment)S8(anterior-septal middle segment), S9(down-septal middle segment),S10(down-middle segement),S11(down-side middle segment) and S12(anterior-side middle segment); the interior ring is apical segment, from the distal papillary muscle extending to end of heart cavity, which comprises4muscle segments:S13(anterior-apical segment),S14(apical-septal segment),S15(the apical segment) and S16(apical-side segement). The each muscle segment and its corresponding coronary artery branches supplying relationship as follow:the left anterior descending coronary artery:S1, S2, S7, S8, S13, S14and S17(the not included in the analysis); the circumflex branch of left coronary artery:S5, S6, S11, S12, S16; the right coronary artery:S3, S4, S9, S10, S15. Finally, contrast to the reversible perfusion abnormality area was displayed by the radionuclide myocardial perfusion, and record the corresponding values of transmural perfusion ratio (TPR) at left ventricular segmental wall.3Statistical methods The statistical software SPSS17version of the package was be used for all data statistical analysis, all data were displayed with x±s, when P<0.05, think the statistics have difference or correlation statistical significance.3.1The corresponding myocardial density CT values of perfusion period, delay10sec,20sec,30sec in resting and in dobutamine stress within the normal control group or the ischemic myocardium with coronary heart disease group were analyzed by paired t test, respectively. The corresponding myocardial density CT values of perfusion period, delay10sec,20sec,30sec in resting or in dobutamine stress between the normal control group and the ischemic myocardium with coronary heart disease group were analyzed by independent samples t test.3.2The corresponding values of ESV, EDV, SV, EF in resting and after dobutamine stress within the normal control group or the ischemic myocardium with coronary heart disease group were analyzed by paired t test, respectively. The corresponding values of ESV, EDV, SV, EF in resting or after dobutamine stress between the normal control group and the ischemic myocardium with coronary heart disease group were analyzed by independent samples t test.3.3The values of transmural perfusion ratio in resting and after dobutamine stress within the normal control group or the ischemic myocardium with coronary heart disease group were analyzed by paired t test, respectively. The values of transmural perfusion ratio in resting or after dobutamine stress between the normal control group and the ischemic myocardium with coronary heart disease group were analyzed by independent samples t test. 4Results4.1The measured values of myocardial CT enhance density at corresponding time points had no statistically significant difference between in the rest and after the dobutamine stress in normal group. The measured values of myocardial CT enhance density at corresponding time points had statistically significant difference between in the rest and after the dobutamine stress in myocardial ischemia of coronary heart disease group, the delay10sec, delay20sec and delay30sec were the most significant statistical difference. The measured values of myocardial CT density had significant difference between the myocardial ischemia of coronary heart disease group and the normal group at corresponding time points in the rest and after the dobutamine stress, in addition to the scan and delay30sec in rest.4.2The values of left ventricular function index had significant statistical difference between in the rest and after the dobutamine stress in normal group except the ejection fraction(EF). The values of left ventricular function index had no significant statistical difference between in the rest and after the dobutamine stress in myocardial ischemia of coronary heart disease group except the ejection fraction (EF). And the values of left ventricular function index had significant statistical difference between the myocardial ischemia of coronary heart disease group and the normal group corresponding in the rest and after the dobutamine stress.4.3The value of transmural perfusion ratio(TPR) had no significant statistical difference between in the rest and after the dobutamine stress in normal group. The value of transmural perfusion ratio(TPR) had significant statistical difference between in the rest and after the dobutamine stress in myocardial ischemia of coronary heart disease group. And the values of transmural perfusion ratio(TPR) had significant statistical difference between the myocardial ischemia of coronary heart disease group and the normal group corresponding in the rest and after the dobutamine stress. Conclusion1. The multi-slice spiral CT perfusion imaging combine with dobutamine stress test can be used to differentiate the normal myocardium and the ischemic myocardium, combined with the TAC curve of myocardial perfusion can reflect the scope and degree of myocardial ischemia in coronary heart disease.2. The multi-slice spiral CT perfusion imaging combine with dobutamine stress test can not only be used to show the morphological changes of coronary artery disease and its influence range of the myocardium, but also can be combined with the ejection fraction(EF) and other left ventricular function indexes to make a comprehensive judging about the myocardial ischemia of coronary heart disease and its influence degrees of cardiac function; it can provide reliable basis for the next step to the treatment choice or observe the effect of treatment in dynamic.3. The320-row spiral CT myocardial perfusion ECG Dynamic Volume Scan technique combine with myocardial stress test can not only combined with the value of myocardial transmural perfusion ratio(TPR) and its color perfusion map to visual detected with or without the abnormal perfusion in the ventricular wall and its scope;but also can more accurately to quantitative evaluation the degree of myocardial segment lesions existed the abnormal perfusion and its characteristic according to the TPR value. |
PDF Full Text Request