Section for Breast Cancer Screening, Cancer Registry of Norway, Oslo, Norway.
Department of Radiology, Haukeland University Hospital, Norway.
Radiography (Lond). 2022 Aug;28(3):772-778. doi: 10.1016/j.radi.2022.03.002. Epub 2022 Apr 3.
We aimed to investigate whether there were any differences in positioning criteria related to the presentation of the pectoralis major muscle (pectoral muscle) for women of different heights using a standardized 60° X-ray tube angle for mammograms in mediolateral oblique (MLO) projection.
Data from MLO mammograms of right breasts of 45,193 women screened in BreastScreen Norway 2016-2019 were used. The positioning criteria were related to the pectoral muscle length (measure A and measure B), width and shape and considered adequate or inadequate depending on the degree of fulfilling the criteria. Data associated with the pectoral muscle were extracted from Volpara, an automated software for breast density assessment. Information on height was obtained from a self-reported questionnaire received by the women together with the invitation to attend the screening program. Women were divided into three groups based on the height percentiles (P) in the Norwegian growth curves: < 25th percentile (<P25th: ≤163 cm), 25th-75th percentile (P25-P75th: 164-170 cm), and >75th percentile (>P75th: >170 cm). Logistic regression was used to analyse the odds of adequate pectoral muscle length A and B, and shape, adjusting each model for screening technique and equipment model. Results were presented with odds ratios (OR) and 95% confidence intervals (CI).
Mean age of the screened women was 61.5 (SD = 4.8) years. The adequate measure for the pectoral muscle length A was obtained for 25.9% (11,724/45,193), length B for 76.3% (34,489/45,193), width for 75.0% (33,894/45,193) and shape for 97.6% (44,118/45,193) of the mammograms. Adjusted odds of an adequate pectoral muscle length A were lower for women of <P25th (OR = 0.90, 95% CI: 0.86-0.95) compared to women of P25-75th. Odds of an adequate pectoral muscle length B were lower for women of <P25th (OR = 0.88, 95% CI 0.84-0.93) and higher for women of >P75th (OR = 1.08, 95% CI 1.02-1.14) compared to women of P25-75. Odds of an adequate pectoral muscle shape were higher for women of <P25th (OR = 1.14, 95%CI 1.08-1.19) and lower for women of >P75th (OR = 0.92, 95% CI 0.87-0.97) compared to women of P25-75th.
The 60° X-ray tube angle might suit most of the female population offered mammographic screening in Norway, but women of a relatively low height (163 cm or lower) might benefit from an X-ray tube angle less than 60-degrees.
Using 60° X-ray tube angle for the MLO mammograms in BreastScreen Norway fit the majority of the participating women. More research is needed to change the protocol associated with the tube angle for women shorter than 163 cm.
本研究旨在探讨在使用标准化 60°X 射线管角度进行乳腺钼靶摄影（MLO）斜位成像时，对于不同身高的女性，胸大肌（胸肌）的定位标准是否存在差异。
使用 2016 年至 2019 年期间参加挪威乳腺癌筛查计划的 45193 名右乳 MLO 乳腺钼靶的影像学数据。定位标准与胸大肌的长度（测量 A 和测量 B）、宽度和形状有关，根据满足标准的程度分为适当或不适当。从 Volpara 软件（一种自动乳腺密度评估软件）中提取与胸大肌相关的数据。身高信息从女性在收到参加筛查计划的邀请时一同收到的自我报告问卷中获得。根据挪威生长曲线的身高百分位数（P）将女性分为三组：<第 25 百分位数（<P25th：≤163cm）、第 25-75 百分位数（P25-P75th：164-170cm）和>第 75 百分位数（>P75th：>170cm）。使用 logistic 回归分析适当的胸大肌长度 A 和 B 以及形状的优势比（OR）和 95%置信区间（CI），每个模型均根据筛查技术和设备模型进行调整。结果以比值比（OR）和 95%置信区间（CI）表示。
接受筛查的女性平均年龄为 61.5（标准差=4.8）岁。适当的胸大肌长度 A 测量值占 25.9%（11724/45193），长度 B 占 76.3%（34489/45193），宽度占 75.0%（33894/45193），形状占 97.6%（44118/45193）。与 P25-75 女性相比，<P25th 女性的胸大肌长度 A 适当的比值比（OR）较低（OR=0.90，95%CI：0.86-0.95）。与 P25-75 女性相比，<P25th 女性的胸大肌长度 B 适当的比值比（OR=0.88，95%CI 0.84-0.93）较低，>P75th 女性的比值比（OR=1.08，95%CI 1.02-1.14）较高。与 P25-75 女性相比，<P25th 女性的胸大肌形状适当的比值比（OR=1.14，95%CI 1.08-1.19）较高，>P75th 女性的比值比（OR=0.92，95%CI 0.87-0.97）较低。
60°X 射线管角度可能适合在挪威接受乳腺钼靶筛查的大多数女性，但身高相对较低（163cm 或以下）的女性可能受益于小于 60°的 X 射线管角度。
在挪威的乳腺钼靶摄影 MLO 中使用 60°X 射线管角度适合大多数参加筛查的女性。需要进一步研究来改变与 163cm 以下女性相关的管角度协议。
