Use of PET/MR Radiomics to Evaluate the Clinical Phenotypes, Response Status of Neoadjuvant Chemotherapy and Long-term Prognosis of Breast Cancer: a Preliminary Study

Purposes and background introduction:

Breast cancer is the most common malignancy in women in our country (2013 cancer registry report, Health Promotion Administration). MRI is a more accurate imaging modality for breast lesion diagnosis, monitoring of treatment response, and local staging than compared with mammography and ultrasound. ¹⁸ F-FDG PET was reported to be used for breast cancer diagnosis, staging, and prediction of treatment response as well. We usually interpret the aforementioned imaging modalities by qualitative methods for decision-making. In recent years, the concept of "Radiomics" is emerging. Radiomics is a process involving the conversion of images (imaging phenotypes) to quantitative data for subsequent data mining to improve decisional making for patient care, to adjust the patient management, that is so-called precision medicine. Radiomics is applied for the diagnostic, prognostic, and predictive purposes of diseases. There are two main approaches to radiomics: First, the semantic approach, which uses the usual radiological lexicon derived from regions of interest; second, the agnostic approach is higher-order, mathematically computed data derived from images instead of the commonly used radiologists' lexicon. MRI and PET can be used in breast radiomics studies. Hybrid PET/MR is a machine that the PET and MRI can be performed on the same table at the same time slot, therefore, the imaging data of MRI and PET can be obtained at the same examination, with less radiation dosage, more reliable lesion mapping than separate examinations of PET/CT and MRI.

Material and methods:

There is a total of 120 patients would like to be included in the study. Our study is to use semantic and agnostic features of radiomics by hybrid PET/MR for:

1. The pre-operative breast cancer patients (without neoadjuvant chemotherapy before operation): to investigate the association of PET/MR imaging data with molecular subtypes, cell proliferation (Ki-67), tumor aggressiveness (by histologic grade).
2. The patients who will receive neoadjuvant chemotherapy (NAC): PET/MR study will be performed for 3 times: pre-MAC (study 1), PET/MR after 1st dose of NAC (study 2), and PET/MR after 3rd or 4th NAC (study 3). We will investigate the predictive ability of PET/MR imaging data for NAC response. And we will investigate which parameters at which series of examinations are more predictive of the final NAC response. Therefore, we can adjust the NAC regimen as early as possible.
3. The breast cancer patients mentioned above: we will investigate the association of PET/MR radiomics data with the probability of metastasis or risk of recurrences and survival.
4. We will also investigate if the BD and BPE (measured on MRI) are associated with molecular subtypes, histologic grade and clinical outcome, risk of metastases, and long-term survival of breast cancer patients for the study participants.