The Diagnosis Of Coronary Artery Disease By Multi-Slice Computed Tomography

Objective: To evaluate the accuracy and limit of 16-slice spiral CT in diagnosis of coronary artery disease we present experimental as well as clinical data. Material and Methods: Sixty consecutive patient in-hospital ward, who were regarded as coronary heart disease, were studied by 16-slice spiral CT and by selective coronary angiography. CT Data were reconstructed to demonstrate the abnormalities of coronary artery were compared with that of angiography ,Before 16-slice spiral CT examination, the partly patients took β-block25-50 mg to control the heart rate under 70 beats/min(bpm) for MSCT, a multi-slice computed tomography system (GE company lightspeed 99)) was used. After a low dose precontrast spiral scan with simultaneously recorded ECG-signal, ultravist were injected into an antecubital vein at 3.5 ml/s (100ml). As soon as the signal density level in the ascending aorta ,which was monitored at a 2s interval ,reached Predefined threshold ,the patient was automatically instructed to maintain an inspiratory breath hold (20.5±1.4s),All examinations were performed during one breath hold. During which the CT data and ECG trace were acquire .scan parameter: collimation width 20mmX20mm feed 27.5mm pitch 0.275,tube voltage 140kv,370mAs,and estimated radiation exposure between 8 and 9mSv. After this feature became available ,prospectively ECG-controlled roentgen tube modulation was applied in patient with a reliable ECG trace to decrease the roentgen output during systole and reduce the exposure by half at low heart rates.Synchronized to the recored ECG ,axial slice were reconstrusted from the acquire MSCT data with the use of an algorithm that uses only the data from a half gantry rotation per slice. The continuous data acquisition allowa slice reconstruction at the different time position within the cardiac cycle .Data from CT angiography were transferred to a computer workstation for post-processing AW4.2 Image reconstruction was performed with retrospective gating under visual optimization at different time points in the diastolic phase. Two blined reviewer independently evaluated the MSCT scans by assessment of the axial slices and with case-dependent application of postprocessing tools,such as multiplanar restruction and thinalab maximum intensity projection.Vessel wall calification was classified as either calium spots.the image tnterpretability was classified as good or poor .the four main coronay branch-left main(LM),left anterior descending (LAD),left circumflex(LCX),and right coronay artery(RCA),inc-ludeng side branches with a diameter of≥2.0mm-were screened for significant narrowing(≥50% diameter reduction)of the lumen.case of disagreement were settled by a joined consenus reading. the AHA classification was used lumen diameter above 2.0mm were analyzed in each patient. Classification three types: artery vessel diameter stenosis under 50%, or between 50%-75%, or above 75%. A coronary segment was considered to have a diagnostic image quality if it was visualizable in its whole lengthand if the vessel lumen was accurately distinguishable. During two –seven days, the transfemoral Judkin technique was used for interventions, selective angiography was performed ,the diameter stenosis,as a percentage of reference diameter,was determined in two orthogonal direction and the average between the two determined the stenosis severity. Results: In the 889coronary artery segments(vessel diameter≥2mm) of 60 patients. Satisfactory lumen assessment for coronary artery segments achieved in 623, but failed in 36segments,CT was 81.1% in consistency with those of conventional coronary a ngiography for assessing mid-stenosis and 84.6% severe stenosis. The sensitivity and specificity for the detection of≥50% stenosis were 82.5%(99/120) and 95.4%(480/503) respectively. When 36coronary artery segments judged unavailable were included in the analysis, the sensitivity was 73.3% (99/120+15), soft atherosclerotic plaques of 12 segment was found in 16-slice spiral CT, resulting from 20%-40% coronary artery stenosis, but conventional coronary angiography showed abnormal lumen diameter. Conclusion: 16-slice spiral CT could be used in noninvasive assessment of significant coronary artery stenosis with high accuracy. The limit was unavoidable artifacts, the doctor can make diagnosis by noninvasive examination and it provide the important information, for percutaneous transluminal coronary angioplasty atherosclerotic plaques intensity of lumen narrowing were evaluated in MSCT, it provide plaques consisting content to the patient's future estimation.But MSCT coronary angiography...