Abstract
Objectives
To evaluate the diagnostic performance of Kaiser score (KS) adjusted with the apparent diffusion coefficient (ADC) (KS+) and machine learning (ML) modeling.
Methods
A dataset of 402 malignant and 257 benign lesions was identified. Two radiologists assigned the KS. If a lesion with KS > 4 had ADC > 1.4 × 10−3 mm2/s, the KS was reduced by 4 to become KS+. In order to consider the full spectrum of ADC as a continuous variable, the KS and ADC values were used to train diagnostic models using 5 ML algorithms. The performance was evaluated using the ROC analysis, compared by the DeLong test. The sensitivity, specificity, and accuracy achieved using the threshold of KS > 4, KS+ > 4, and ADC ≤ 1.4 × 10−3 mm2/s were obtained and compared by the McNemar test.
Results
The ROC curves of KS, KS+, and all ML models had comparable AUC in the range of 0.883–0.921, significantly higher than that of ADC (0.837, p < 0.0001). The KS had sensitivity = 97.3% and specificity = 59.1%; and the KS+ had sensitivity = 95.5% with significantly improved specificity to 68.5% (p < 0.0001). However, when setting at the same sensitivity of 97.3%, KS+ could not improve specificity. In ML analysis, the logistic regression model had the best performance. At sensitivity = 97.3% and specificity = 65.3%, i.e., compared to KS, 16 false-positives may be avoided without affecting true cancer diagnosis (p = 0.0015).
Conclusion
Using dichotomized ADC to modify KS to KS+ can improve specificity, but at the price of lowered sensitivity. Machine learning algorithms may be applied to consider the ADC as a continuous variable to build more accurate diagnostic models.
Key Points
• When using ADC to modify the Kaiser score to KS+, the diagnostic specificity according to the results of two independent readers was improved by 9.4–9.7%, at the price of slightly degraded sensitivity by 1.5–1.8%, and overall had improved accuracy by 2.6–2.9%.
• When the KS and the continuous ADC values were combined to train models by machine learning algorithms, the diagnostic specificity achieved by the logistic regression model could be significantly improved from 59.1 to 65.3% (p = 0.0015), while maintaining at the high sensitivity of KS = 97.3%, and thus, the results demonstrated the potential of ML modeling to further evaluate the contribution of ADC.
• When setting the sensitivity at the same levels, the modified KS+ and the original KS have comparable specificity; therefore, KS+ with consideration of ADC may not offer much practical help, and the original KS without ADC remains as an excellent robust diagnostic method.
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Abbreviations
- ADC:
-
Apparent diffusion coefficient
- AUC:
-
Area under ROC curve
- BI-RADS:
-
Breast Imaging Reporting and Data System
- BPE:
-
Background parenchymal enhancement
- CI:
-
Confidence interval
- DCE:
-
Dynamic contrast-enhanced
- DCIS:
-
Ductal carcinoma in situ
- DWI:
-
Diffusion-weighted imaging
- ICC:
-
Intraclass correlation coefficient
- KS:
-
Kaiser score
- LDA:
-
Linear discriminant analysis
- LR:
-
Logistic regression
- ML:
-
Machine learning
- MRI:
-
Magnetic resonance imaging
- NB:
-
Naive Bayes
- ROC:
-
Receiver operator characteristic
- ROI:
-
Region of interest
- SVM_L:
-
Linear kernel support vector machine
- SVM_R:
-
Radial kernel support vector machine
- VIBRANT:
-
Volume imaging for breast assessment
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Funding
This work was supported by the Key Laboratory of Intelligent Medical Imaging of Wenzhou (No. 2021HZSY0057), the Key Laboratory of Alzheimer’s Disease of Zhejiang Province, Institute of Aging, Wenzhou Medical University, Wenzhou, Zhejiang, China, Wenzhou Science & Technology Bureau (No. Y20180185), the Medical Health Science and Technology Project of Zhejiang Province Health Commission (No. 2019KY102), the National Cancer Institute of the National Institutes of Health under award numbers P30 CA062203, R01 CA127927, and R21 CA208938, and the UC Irvine Comprehensive Cancer Center using UCI Anti-Cancer Challenge funds.
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The scientific guarantor of this publication is Min-Ying Su, PhD.
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Institutional Review Board approval was obtained from Institutional Review Board of the First Affiliated Hospital of Wenzhou Medical University (approval number 2021-R007).
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Chen, ZW., Zhao, YF., Liu, HR. et al. Assessment of breast lesions by the Kaiser score for differential diagnosis on MRI: the added value of ADC and machine learning modeling. Eur Radiol 32, 6608–6618 (2022). https://doi.org/10.1007/s00330-022-08899-w
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DOI: https://doi.org/10.1007/s00330-022-08899-w