Associations Between Apparent Diffusion Coefficient Values of Breast Tumors Presenting as Non-Mass Enhancement and Ki-67 Index
5 affiliations
- 1Department of Diagnostic and Interventional Radiology, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
- 2Department of Diagnostic and Interventional Radiology, University Hospital of Dubrava, Avenija Gojka Šuška 6, 10000 Zagreb, Croatia
- 3Department of Pathology, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
- 4Independent Researcher, 21000 Split, Croatia
- 5Department of Abdominal Surgery, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia
Abstract
Objectives: This study aimed to investigate whether apparent diffusion coefficient (ADC) values of malignant breast lesions presenting as non-mass enhancement (NME) are associated with the Ki-67 proliferation index. Materials and Methods: This retrospective, single-center study included 70 patients with malignant breast lesions presenting as NME on MRI. Patients were divided into two groups according to their Ki-67 index; Group KL (Ki-67 < 20%) and KH (Ki-67 ≥ 20%). All examinations were performed on a 1.5T scanner. Two radiologists, blinded to histopathology, independently outlined the whole NME on every subtraction slice on which it was visible and transferred these regions of interest to the ADC maps; the mean ADC value was used for subsequent analysis. Results: Mean ADC values were lower in Group KH than in Group KL (0.897 ± 0.158 vs. 1.116 ± 0.155 × 103 mm2/s, p < 0.001) and were inversely correlated with the Ki-67 index (Spearman’s ρ = −0.458, 95% CI −0.626 to −0.250, p < 0.001). A high Ki-67 index remained associated with lower ADC values after adjustment for molecular subtype (b = −0.228 × 10−3 mm2/s; p < 0.001). ROC curve analysis yielded an AUC of 0.833 (95% CI 0.725 to 0.912). The exploratory Youden threshold of 1.045 × 10−3 mm2/s yielded a sensitivity of 85.7% and a specificity of 66.7%. Bootstrap resampling confirmed that the AUC was internally stable (mean 0.832, 95% CI 0.728 to 0.918). Conclusions: In malignant NME, lower ADC values are associated with a higher Ki-67 index. The ADC may add noninvasive information on tumor proliferation but cannot replace histopathology. The proposed threshold is exploratory and needs external validation before clinical use.
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BibTeX
@article{peric2026associations,
title = {{Associations Between Apparent Diffusion Coefficient Values of Breast Tumors Presenting as Non-Mass Enhancement and Ki-67 Index}},
author = {Iva Perić and Boris Brkljačić and Tade Tadić and Kristian Jerković and Krešimir Dolić and Martina Luetić and Monika Bilandžić and Matija Borić and Marija Ćavar},
journal = {Cancers},
year = {2026},
month = nov,
doi = {10.3390/cancers18213560},
url = {https://www.mdpi.com/2072-6694/18/21/3560},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Associations Between Apparent Diffusion Coefficient Values of Breast Tumors Presenting as Non-Mass Enhancement and Ki-67 Index
AU - Iva Perić
AU - Boris Brkljačić
AU - Tade Tadić
AU - Kristian Jerković
AU - Krešimir Dolić
AU - Martina Luetić
AU - Monika Bilandžić
AU - Matija Borić
AU - Marija Ćavar
PY - 2026
DA - 2026/11/05
JO - Cancers
DO - 10.3390/cancers18213560
UR - https://www.mdpi.com/2072-6694/18/21/3560
AB - Objectives: This study aimed to investigate whether apparent diffusion coefficient (ADC) values of malignant breast lesions presenting as non-mass enhancement (NME) are associated with the Ki-67 proliferation index. Materials and Methods: This retrospective, single-center study included 70 patients with malignant breast lesions presenting as NME on MRI. Patients were divided into two groups according to their Ki-67 index; Group KL (Ki-67 < 20%) and KH (Ki-67 ≥ 20%). All examinations were performed on a 1.5T scanner. Two radiologists, blinded to histopathology, independently outlined the whole NME on every subtraction slice on which it was visible and transferred these regions of interest to the ADC maps; the mean ADC value was used for subsequent analysis. Results: Mean ADC values were lower in Group KH than in Group KL (0.897 ± 0.158 vs. 1.116 ± 0.155 × 103 mm2/s, p < 0.001) and were inversely correlated with the Ki-67 index (Spearman’s ρ = −0.458, 95% CI −0.626 to −0.250, p < 0.001). A high Ki-67 index remained associated with lower ADC values after adjustment for molecular subtype (b = −0.228 × 10−3 mm2/s; p < 0.001). ROC curve analysis yielded an AUC of 0.833 (95% CI 0.725 to 0.912). The exploratory Youden threshold of 1.045 × 10−3 mm2/s yielded a sensitivity of 85.7% and a specificity of 66.7%. Bootstrap resampling confirmed that the AUC was internally stable (mean 0.832, 95% CI 0.728 to 0.918). Conclusions: In malignant NME, lower ADC values are associated with a higher Ki-67 index. The ADC may add noninvasive information on tumor proliferation but cannot replace histopathology. The proposed threshold is exploratory and needs external validation before clinical use.
SN - 2072-6694
ER -