The association between MRI findings and breast cancer subtypes: focused on the combination patterns on diffusion-weighted and T2-weighted images.
PURPOSE
To assess morphology on diffusion-weighted imaging (DWI) and intratumoral signal intensity (SI) on T2-weighted images (T2WI) of breast carcinomas, and to evaluate the association between the combined DWI and T2WI findings and breast cancer subtypes.


METHODS
Two hundred and eighty breast cancer patients who underwent breast MRI prior to therapy were included in this retrospective study. All had invasive carcinomas, which were classified into five subtypes: Luminal A-like (n = 149), Luminal B-like (n = 63), Hormone receptor-positive HER2 (n = 31), Hormone receptor-negative HER2 (n = 13), or Triple-negative (TN) (n = 24). Based on the morphology on DWI, the tumors were classified into two patterns: DWI-homogeneous or DWI-heterogeneous. If DWI-heterogeneous, an assessment of intratumoral SI on T2WI was performed: tumors with intratumoral high/low SI on T2WI were classified as Hete-H/Hete-L, respectively. The associations between (1) the morphological patterns on DWI and the five subtypes, and (2) the intratumoral SI patterns on T2WI and the five subtypes in DWI-heterogeneous were evaluated.


RESULTS
There was a significant association between (1) the morphological patterns on DWI and the five subtypes (p < 0.0001), and (2) the intratumoral SI patterns on T2WI and the five subtypes in DWI-heterogeneous (p < 0.0001). DWI-homogeneous was dominant in Luminal A-like (67.1%), and Hete-H was dominant in TN type (75%). Hete-H, suggesting the presence of intratumoral necrosis, included high proliferative and/or aggressive subtypes more frequently (80%) than Hete-L, suggesting the presence of fibrotic focus. Fibrotic focus was seen more commonly in the luminal subtypes.


CONCLUSION
The combined findings on DWI and T2WI revealed breast carcinomas that were associated with particular subtypes.
['Yuen|Sachiko|S|', 'Monzawa|Shuichi|S|', 'Yanai|Seiji|S|', 'Matsumoto|Hajime|H|', 'Yata|Yoshihiro|Y|', 'Ichinose|You|Y|', 'Deai|Teruyuki|T|', 'Hashimoto|Takashi|T|', 'Tashiro|Takashi|T|', 'Yamagami|Kazuhiko|K|']
D000328:Adult D000368:Aged D001940:Breast D001943:Breast Neoplasms D018270:Carcinoma, Ductal, Breast D017024:Chemotherapy, Adjuvant D003287:Contrast Media D038524:Diffusion Magnetic Resonance Imaging D005260:Female D006801:Humans D008408:Mastectomy D008875:Middle Aged D020360:Neoadjuvant Therapy D018719:Receptor, ErbB-2 D011960:Receptors, Estrogen D011980:Receptors, Progesterone D012189:Retrospective Studies
Breast cancer T2-weighted imaging Diffusion-weighted imaging Magnetic resonance imaging Molecular subtype