Multimodal MR functional imaging for pathological grading and monitoring trastuzumab response in HER2-positive breast cancer.

Accurate noninvasive assessment of tumor grade and therapeutic response in HER2-positive breast cancer remains challenging. This prospective, single-center study aimed to evaluate the diagnostic value of multimodal MR functional imaging in grading malignant breast tumors and monitoring trastuzumab response. Eighty HER2-positive patients confirmed by IHC/FISH were enrolled, including 41 low-grade and 39 high-grade tumors (Nottingham grading system). Patients underwent comprehensive MR imaging, including diffusion tensor imaging, MR spectroscopy and perfusion imaging at baseline and during therapy. Tumor morphological features (size, necrosis, hemorrhage, edema, boundary clarity) and functional MR parameters (FA, tCho, MTT, TTP) were analyzed for correlation with pathological grade and treatment response. High-grade tumors showed larger size, more necrosis, hemorrhage and edema (P<0.05). Functional MR parameters, particularly tCho, MTT and TTP, correlated positively with tumor grade (P<0.05). ROC analysis demonstrated high diagnostic accuracy (sensitivity 89.2%, specificity 79.5%, AUC=0.887). Typical MR imaging patterns also reflected trastuzumab responsiveness, indicating potential for noninvasive monitoring of therapy. Multimodal MR functional imaging thus provides a sensitive and specific tool for tumor grading and evaluation of targeted therapeutic response.