多层螺旋CT重建参数对头颈部肿瘤MPR图像质量的影响

目的　分析多层螺旋CT(MSCT)重建及重组参数对头颈部肿瘤MPR图像质量的影响 ,以便选择最佳的参数组合。资料与方法　使用GELightspeedUltra 8层螺旋CT扫描机对 6 7例头颈部肿瘤患者进行扫描。分为两部分 ,第一部分 2 8例 ,分别对原始数据进行 1.2 5mm、2 .5mm层厚的轴面重建 ,重叠率均为 5 0 %。图像重组时 ,分别采用层厚 1mm、2mm、3mm和 5mm。第二部分 39例 ,分别采用 0 %、2 5 %、5 0 %和 75 %的重叠率和 1.2 5mm层厚进行轴面重建 ,然后采用 1mm层厚进行图像重组。应用双盲法评价各组图像质量 ,并进行统计学处理。结果　第一部分 ,在软组织、骨质和伪影方面组内差异有极显著性 (P <0 .0 1) ,1.2 5mm层厚轴面重建的各组MPR图像中 ,1mm层厚组对软组织和骨质的显示好于其他各组 (P <0 .0 1)。第二部分 ,在软组织、病变、骨质和伪影方面组内差异有极显著性 (P <0 .0 1) ;在软组织和病变方面 ,5 0 %与 75 %重叠率图像质量最佳 ,两者差异无显著性 (P >0 .0 5 ) ;在骨质方面 75 %重叠率组图像质量高于 5 0 %组 (P <0 .0 5 ) ;在伪影方面 ,5 0 %重叠率组好于 75 %组 (P <0 .0 1)。结论　头颈部肿瘤MSCT图像后处理采用 1.2 5mm层厚、5 0 %重叠率进行轴面重建后 ,用 1mm层厚的MPR图像能很好地显示软组织、病变

Reconstruction and Reformation Parameter in Multislice Helical CT Study for Head and Neck Neoplasms: Its Effect on MPR Quality

Objective To study the effect of reconstruction and reformation parameters on MPR image quality in multislice helical CT study for head and neck neoplasms, to obtain the optimal reconstruction parameters.Materials and Methods Helical CT scanning (GE Lightspeed Ultra, 8 slices), using 1.25 mm collimation and 0.875 pitch, was performed in 67 patients with head and neck neoplasms. The patients were divided into two groups. Group 1 (n=28): the raw data was reconstructed with 1.25 mm and 2.5 mm thick section with 50% section overlap, MPR images were obtained with 1 mm, 2 mm, 3 mm and 5 mm reformation. Group 2 (n=39): the raw data was reconstructed with 1.25 mm thick section with 0%, 25%, 50% and 75% section overlap, MPR images were obtained with 1 mm reformation. Using double blind method, the images of each group were separately evaluated by two radiologists. The results were statistically analyzed.Results In group 1, the quality of MPR image using 1.25 mm reconstruction and 1 mm reformation was superior to the images using other parameters in displaying soft tissue and bony structure (P<0.01). In group 2, significant difference in demonstrating soft tissue, lesion and bone, as well as in occurring artifacts existed between the images using different parameters (P<0.01). In displaying soft tissue and lesions, images using 50% and images using 75% section overlap showed the same best quality (P>0.05). For observing bone structure, the image quality using 75% section overlap was better than that using 50% section overlap (P<0.05). In reducing artifacts, reformation using 50% section overlap was superior to that using 75% section overlap (P<0.01).Conclusion For well displaying the soft tissue, lesion and bone on MPR images with multislice helical CT study in patients with head and neck neoplasm, parameters of 1.25 mm thick reconstruction with 50% section overlap and 1 mm reformation are of choice.