Department of Radiology and Nuclear Medicine, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
Department of Radiology/Biomedical Engineering and Physics, Academic Medical Center Amsterdam, PO Box 22660, 1100 DD, Amsterdam, The Netherlands.
Breast Cancer Res. 2017 Nov 28;19(1):126. doi: 10.1186/s13058-017-0917-3.
In mammography, breast compression is applied to reduce the thickness of the breast. While it is widely accepted that firm breast compression is needed to ensure acceptable image quality, guidelines remain vague about how much compression should be applied during mammogram acquisition. A quantitative parameter indicating the desirable amount of compression is not available. Consequently, little is known about the relationship between the amount of breast compression and breast cancer detectability. The purpose of this study is to determine the effect of breast compression pressure in mammography on breast cancer screening outcomes.
We used digital image analysis methods to determine breast volume, percent dense volume, and pressure from 132,776 examinations of 57,179 women participating in the Dutch population-based biennial breast cancer screening program. Pressure was estimated by dividing the compression force by the area of the contact surface between breast and compression paddle. The data was subdivided into quintiles of pressure and the number of screen-detected cancers, interval cancers, false positives, and true negatives were determined for each group. Generalized estimating equations were used to account for correlation between examinations of the same woman and for the effect of breast density and volume when estimating sensitivity, specificity, and other performance measures. Sensitivity was computed using interval cancers occurring between two screening rounds and using interval cancers within 12 months after screening. Pair-wise testing for significant differences was performed.
Percent dense volume increased with increasing pressure, while breast volume decreased. Sensitivity in quintiles with increasing pressure was 82.0%, 77.1%, 79.8%, 71.1%, and 70.8%. Sensitivity based on interval cancers within 12 months was significantly lower in the highest pressure quintile compared to the third (84.3% vs 93.9%, p = 0.034). Specificity was lower in the lowest pressure quintile (98.0%) compared to the second, third, and fourth group (98.5%, p < 0.005). Specificity of the fifth quintile was 98.4%.
Results suggest that if too much pressure is applied during mammography this may reduce sensitivity. In contrast, if pressure is low this may decrease specificity.
在乳房 X 光摄影中，需要对乳房进行压迫以减少乳房的厚度。虽然广泛认为需要对乳房进行有力的压迫以确保可接受的图像质量，但指南仍然不清楚在进行乳房 X 光摄影采集时应该施加多少压迫。没有指示所需压迫量的定量参数。因此，人们对乳房压迫量与乳腺癌可检测性之间的关系知之甚少。本研究的目的是确定乳房 X 光摄影中乳房压迫压力对乳腺癌筛查结果的影响。
我们使用数字图像分析方法确定了参加荷兰基于人群的两年一次乳腺癌筛查计划的 57179 名女性的 132776 次检查中的乳房体积、致密百分比体积和压力。通过将压缩力除以乳房与压迫板之间的接触面积来估算压力。将数据分为压力五分位数，为每个组确定筛查检出的癌症数量、间隔期癌症数量、假阳性数量和真阴性数量。使用广义估计方程来解释同一女性的检查之间的相关性，并在估计敏感性、特异性和其他性能指标时考虑乳房密度和体积的影响。使用两次筛查之间发生的间隔期癌症和筛查后 12 个月内发生的间隔期癌症计算敏感性。进行了两两比较以检查显著差异。
致密百分比体积随压力的增加而增加，而乳房体积随压力的增加而减小。随着压力的增加，五分位数的敏感性分别为 82.0%、77.1%、79.8%、71.1%和 70.8%。基于 12 个月内间隔期癌症的敏感性在最高压力五分位数中明显低于第三五分位数（84.3%比 93.9%，p=0.034）。最低压力五分位数的特异性（98.0%）明显低于第二、第三和第四五分位数（98.5%，p<0.005）。第五五分位数的特异性为 98.4%。
结果表明，如果在乳房 X 光摄影中施加的压力过大，则可能会降低敏感性。相反，如果压力过低，则可能会降低特异性。
