IMAR对起搏器植入患者胸部CT扫描的应用价值

Application Values of IMAR Algorithm on CT Scanning of Cardiac Pacemaker Implanted Patients Based on Chest Phantom Study

目的:通过仿真胸部体模对伪影区域内肺结节及肺组织显示效果的分析,评价IMAR算法对心脏起搏器植入患者CT扫描的应用价值。方法:在胸部仿真体模内置入模拟肺结节60个,分别在心脏起搏器放置前后进行胸部CT扫描(常规剂量及低剂量扫描),图像分别采用无IMAR和有IMAR两种方式进行重建。比较肺结节的检出率,测量模拟肺结节CT值与其标称CT值的差值,并比较图像的噪声值、SNR、CNR值,并对主观图像质量评分。结果:低剂量胸部CT扫描时,使用IMRA检出结节数目较多;使用IMAR算法磨玻璃肺结节的测量CT值与标称CT值的差值较小。使用IMAR重建时图像SNR及CNR值均较高。IMAR重建图像质量主观评分高于未使用IMAR。结论:IMAR算法能减轻心脏起搏器金属伪影,提高低剂量胸部CT对伪影区域结节的检出率,提高伪影区域磨玻璃肺结节的显示效果,提高伪影区域图像质量。

Purpose： To evaluate the application values of IMAR（iterative metal artifact reduction）algorithm on CT scanning of cardiac pacemaker implanted patients. Methods： Sixty simulated pulmonary nodules were inserted into the anthropomorphic phantom. The phantom was scanned with and without the pacemaker respectively（low-dose CT and regular dose CT scan respectively）. Images were reconstructed with and without IMAR respectively. The sensitivities in detection of pulmonary nodules and their deviation of CT values were compared between the two reconstructed methods. On the regular dose CT scan images, the image noise, SNR and CNR were calculated. And the subjective image quality scores were evaluated by two radiologists. Results： All the pulmonary nodules were detected by using the low-dose CT scan with IMRA reconstruction algorithm; the simulated pulmonary nodules with diameter of 3mm and CT value of 800 HU were not detected without the use of IMRA algorithm. For the pulmonary nodules with a standard CT number of-800 HU and-650 HU, the deviation of CT values were significantly smaller with IMAR algorithm than that without it. The SNR and CNR were higher when using IMAR. The subjective image quality scores of the images reconstructed using IMAR were higher than that without IMAR algorithm. Conclusion： IMAR algorithm can significantly reduce mental artifact of cardiac pacemaker, and improve the sensitivities in detection of pulmonary nodules with low-dose CT scan, the display effect of the nodules with ground-glass opacity（GGO）, and image quality of the areas with artifacts.