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目的通过实验对比研究,探讨基于模型的完全迭代算法(IMR)技术对肾脏小结石的诊断价值。方法制作肾结石体模:单个重量(300±30)g的猪肾4个,将每个肾脏自肾脏一极沿冠状面切开至肾盂水平,将大小分别为2 mm、1 mm、0.5 mm的尿酸结石各24枚(每个肾脏6枚)分别植入肾皮质、肾髓质及肾盂,将植入结石的肾脏放置于注满生理盐水圆柱形有机容器,对体模进行CT扫描,用滤波反投影法(FBP)、高级迭代重组算法(iDose~4)、IMR技术分别重组出层厚为0.8 mm、层间距为0.3 mm的图像,对不同尺寸结石诊断的敏感性、特异性、准确性、数量、诊断结石的信心及图像质量进行评估。结果主观评价指标:(1)IMR图像的质量评分相对于FBP及iDose~4图像,有统计学意义。(2)IMR图像的噪声低于FBP及iDose~4图像,且iDose~4图像的噪声低于FBP。(3)对于2 mm、1 mm的结石三种重组方法对结石的检出率(均为100%)及正确诊断的信心(均为3分)没有统计学意义。对于0.5 mm的结石IMR技术对结石的检出率及正确诊断的信心与FBP和iDose~4比较,P<0.05,有统计学意义。客观评价指标:FBP、iDose~4、IMR技术所得图像的噪声和信噪比分别为[(5.8±0.5)HU,9.1±0.6]、[(4.1±0.3)HU,13.5±0.5]、[(1.9±0.3)HU,28.2±0.5],三组图像的噪声和信噪比两两比较,差异均有统计学意义。结论相对于FBP与iDose~4图像,IMR技术能在提高图像质量的同时提高微小结石诊断的准确性。
Objective To explore the diagnostic value of the model-based complete iterative algorithm (IMR) for the diagnosis of small kidney stones through experimental comparative studies. Methods Nephrolithotage phantom was made: 4 pigs and kidneys of single weight (300 ± 30) g, each kidney was incised along the coronal plane from the kidneys to the renal pelvis, and the sizes were 2 mm, 1 mm and 0.5 mm Of each uric acid stones 24 (each kidney 6) were implanted into the renal cortex, renal medulla and renal pelvis, the implanted stone placed in a kidney filled with saline cylindrical organic container, the phantom CT scan with FBP, iDose ~ 4, and IMR techniques were used to reconstruct images with a layer thickness of 0.8 mm and a layer spacing of 0.3 mm respectively. The sensitivity, specificity and accuracy of FBP, Sex, quantity, confidence in the diagnosis of the stone and image quality assessment. Results Subjective evaluation index: (1) The quality score of IMR image was statistically significant compared with FBP and iDose ~ 4 images. (2) The noise of IMR images is lower than that of FBP and iDose ~ 4 images, and the noise of iDose ~ 4 images is lower than FBP. (3) There was no statistical significance in the detection rate of stones (both 100%) and correct diagnosis (all 3 points) for the three kinds of reconstruction methods of 2 mm and 1 mm stones. For 0.5mm stone IMR technology, the detection rate of stone and the confidence of correct diagnosis with FBP and iDose ~ 4, P <0.05, statistically significant. Objective evaluation index: The noise and signal-to-noise ratio of the images obtained by FBP, iDose ~ 4 and IMR are [(5.8 ± 0.5) HU, 9.1 ± 0.6], [(4.1 ± 0.3) HU, 13.5 ± 0.5] 1.9 ± 0.3) HU, 28.2 ± 0.5]. The noise and signal-to-noise ratio of the three groups of images were compared in any pairwise and the differences were statistically significant. Conclusion Compared with FBP and iDose ~ 4 images, IMR can improve the diagnostic accuracy of microlithiasis while improving the image quality.