Comparison of power spectra for tomosynthesis projections and reconstructed images
Comparison of power spectra for tomosynthesis projections and reconstructed images
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DOI：
10.1118/1.3116774
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发表时间：
2009-05-01
期刊：
影响因子：
3.8
通讯作者：
Nishikawa, Robert
中科院分区：
文献类型：
--
作者：
Engstrom, Emma;Reiser, Ingrid;Nishikawa, Robert
Burgess [Med.Phys.28，419-437（2001）]表明，乳房X线照相术乳房背景的功率谱遵循幂律，并且病变可检测性受到幂律指数β的影响，幂律指数β测量背景中的结构量。根据Burgess的研究，作者测量并比较了断层合成投影和重建切片中乳腺摄影背景的幂律指数，以研究断层合成成像对背景结构的影响。我们的数据集包括55例患者病例。对于每种情况下，感兴趣的区域（ROI）从投影图像和重建切片中提取。通过取ROI的傅里叶变换的平方模来计算每个ROI的周期图。确定每个周期图的幂律指数，并对从每个患者数据集的所有投影或重建切片中提取的所有ROI进行平均。对于投影，55例病例的平均β为3.06（标准差为0.21），而相应重建的平均β为2.87（0.24）。在55个病例中，投影ROI和重建ROI之间给定患者的β差异平均为0.194，具有统计学显著性（p < 0.001）。投影和重建的β平均值之间差异的95% CI为[0.170，0.218]。结果与观察结果一致，即与投影乳房X线摄影相比，断层合成切片中的乳房结构数量减少，这可能导致病变可检测性提高。
Burgess [Med. Phys. 28, 419-437 (2001)] showed that the power spectrum of mammographic breast background follows a power law and that lesion detectability is affected by the power-law exponent beta which measures the amount of structure in the background. Following the study of Burgess , the authors measured and compared the power-law exponent of mammographic backgrounds in tomosynthesis projections and reconstructed slices to investigate the effect of tomosynthesis imaging on background structure. Our data set consisted of 55 patient cases. For each case, regions of interest (ROIs) were extracted from both projection images and reconstructed slices. The periodogram of each ROI was computed by taking the squared modulus of the Fourier transform of the ROI. The power-law exponent was determined for each periodogram and averaged across all ROIs extracted from all projections or reconstructed slices for each patient data set. For the projections, the mean beta averaged across the 55 cases was 3.06 (standard deviation of 0.21), while it was 2.87 (0.24) for the corresponding reconstructions. The difference in beta for a given patient between the projection ROIs and the reconstructed ROIs averaged across the 55 cases was 0.194, which was statistically significant (p < 0.001). The 95% CI for the difference between the mean value of beta for the projections and reconstructions was [0.170, 0.218]. The results are consistent with the observation that the amount of breast structure in the tomosynthesis slice is reduced compared to projection mammography and that this may lead to improved lesion detectability.