Background Computer-aided detection (CAD) can detect breast lesions by using an enhancement threshold. Threshold means the percentage of increased signal intensity in post-contrast imaging compared to precontrast imaging. If the pixel value of the enhanced tumor increases above the set threshold, CAD provides the size of the tumor, which is calculated differently depending on the set threshold. Therefore, CAD requires the accurate setting of thresholds. We aimed to compare the diagnostic accuracy of tumor size measurement using MRI and CAD with 3 most commonly used thresholds and to identify which threshold is appropriate on CAD in breast cancer patients. Methods A total of 130 patients with breast cancers (80 invasive cancers and 50 ductal carcinoma in situ [DCIS]) who underwent preoperative MRI with CAD and surgical treatment were included. Tumor size was manually measured on first contrast-enhanced MRI and acquired by CAD using 3 different thresholds (30, 50, and 100%) for each tumor. Tumor size measurements using MRI and CAD were compared with pathological sizes using Spearman correlation analysis. For comparison of size discrepancy between imaging and pathology, concordance was defined as estimation of size by imaging within 5 mm of the pathological size. Concordance rates were compared using Chi-square test. Results For both invasive cancers and DCIS, correlation coefficient rho ( r ) between tumor size on imaging and pathology was highest at CAD with 30% threshold, followed by MRI, CAD with 50% threshold, and CAD with 100% threshold (all p < 0.05). For invasive cancers, the concordance rate of 72.5% at CAD with 30% threshold showed no difference with that of 62.5% at MRI ( p = 0.213). For DCIS, the concordance rate of 30.0% at CAD with 30% threshold showed no difference with that of 36.0% at MRI ( p = 0.699). Compared to MRI, higher risk of underestimation was noted when using CAD with 50% or 100% threshold for invasive cancers and when using CAD with 100% threshold for DCIS. Conclusion For CAD analysis, 30% threshold is the most appropriate threshold whose accuracy is comparable to manual measurement on MRI for tumor size measurement. However, clinicians should be aware of the higher risk of underestimation when using CAD with 50% threshold for tumor staging in invasive cancers.

中文翻译：

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乳腺癌患者术前肿瘤大小测量：哪个阈值适合用于乳腺 MRI 的计算机辅助检测？

背景 计算机辅助检测 (CAD) 可以通过使用增强阈值来检测乳房病变。阈值是指与对比前成像相比，对比后成像中信号强度增加的百分比。如果增强肿瘤的像素值增加到高于设定的阈值，CAD 会提供肿瘤的大小，根据设定的阈值进行不同的计算。因此，CAD 需要准确设置阈值。我们的目的是将使用 MRI 和 CAD 测量肿瘤大小的诊断准确性与 3 个最常用的阈值进行比较，并确定哪个阈值适用于乳腺癌患者的 CAD。方法 共130例乳腺癌患者（80例浸润癌和50例导管原位癌[DCIS]）行术前MRI合并CAD和手术治疗。在第一次对比增强 MRI 上手动测量肿瘤大小，并通过 CAD 对每个肿瘤使用 3 个不同的阈值（30%、50% 和 100%）获取。使用 MRI 和 CAD 测量的肿瘤大小与使用 Spearman 相关分析的病理大小进行比较。为了比较影像学和病理学之间的大小差异，一致性被定义为通过在病理学大小的 5 mm 内成像来估计大小。使用卡方检验比较一致性率。结果 对于浸润性癌和 DCIS，影像学和病理学的肿瘤大小之间的相关系数 rho ( r ) 在 CAD 时最高，阈值为 30%，其次是 MRI、CAD 阈值为 50% 和 CAD 阈值为 100%（所有 p < 0.05）。对于浸润性癌症，CAD 的一致性率为 72.5%，阈值为 30%，与 62 没有差异。MRI 时为 5% (p = 0.213)。对于 DCIS，CAD 的 30.0% 与 30% 阈值的一致率与 MRI 的 36.0% 没有差异（p = 0.699）。与 MRI 相比，当使用具有 50% 或 100% 阈值的 CAD 用于侵袭性癌症和使用具有 100% 阈值的 CAD 用于 DCIS 时，注意到有更高的低估风险。结论 对于 CAD 分析，30% 阈值是最合适的阈值，其准确性可与 MRI 手动测量肿瘤大小测量相媲美。然而，临床医生应该意识到在浸润性癌症中使用具有 50% 阈值的 CAD 进行肿瘤分期时，低估的风险更高。当使用具有 50% 或 100% 阈值的 CAD 用于侵袭性癌症和使用具有 100% 阈值的 CAD 用于 DCIS 时，注意到低估风险更高。结论 对于 CAD 分析，30% 阈值是最合适的阈值，其准确度可与 MRI 手动测量肿瘤大小测量相媲美。然而，临床医生应该意识到在浸润性癌症中使用具有 50% 阈值的 CAD 进行肿瘤分期时，低估的风险更高。当使用具有 50% 或 100% 阈值的 CAD 用于侵袭性癌症和使用具有 100% 阈值的 CAD 用于 DCIS 时，注意到被低估的风险更高。结论 对于 CAD 分析，30% 阈值是最合适的阈值，其准确性可与 MRI 手动测量肿瘤大小测量相媲美。然而，临床医生应该意识到在浸润性癌症中使用具有 50% 阈值的 CAD 进行肿瘤分期时，低估的风险更高。