Breast cancer is the most common type of cancer in Norwegian women, with 4,224 new cases in 2022. More precise diagnosis are expected to result in more accurate assessment of treatment effect, and to contribute to both providing better treatment and reducing overtreatment. Fibroblast activating protein (FAP) is expressed in the tumor stroma of 90% of all epithelial-based tumors, including breast tumors. Inhibitors for this protein (FAPI) has been developed for use as radioactive tracers. Breast tumors of various histopathological types, and local metastatic lymph nodes, have shown high uptake for such tracers. The main aim of this project is to establish 18F-FAPI PET/MRI for use in breast cancer in a wide range of disease stages. We will evaluate how FAPI PET/MRI correlates with histopathological assessment, the method's ability to grade tumors - including assessment of treatment - compared to CT, scintigraphy and FDG PET/CT, and ability to detect local recurrence.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
60
The patients will be injected intravenously with 2 MBq/kg 18F-FAPI, 60 minutes before the PET/MRI acquisition. The PET/MRI examinations will be performed on a Siemens Biograph mMR (Siemens Healthcare, Erlangen, Germany) with software version VE11P. Static PET will be acquired simultaneously with MRI using two protocols; a one bed position protocol in prone position covering the breast and a whole body 4-5 bed position protocol in supine position covering brain to thighs. Total acquisition time of the breast protocol will be approximately 20 minutes. Total acquisition time of the whole-body protocol will be approximately 30 minutes.
Diagnostic accuracy of 18F-FAPI-PET/MRI in detection of breast cancer lesions
Diagnostic accuracy (sensitivity, specificity, positive predictive value, negative predictive value) of 18F-FAPI-PET/MRI in detecting breast cancer lesions, including primary tumors, regional lymph node metastases, distant metastases, and local/distant recurrences. Interpretation will be based on consensus assessment by nuclear medicine physicians and radiologists. Histopathology and/or conventional imaging (CT, FDG-PET, bone scintigraphy) will serve as the reference standards.
Time frame: Baseline
Correlation of standardized uptake values of 18F-FAPI to histologically proven characteristics of the breast cancer lesions
Quantitative PET compared to standard histopathology of breast tumours and axillary lymph nodes, including number and size, grading, receptor status, and histological type
Time frame: Baseline
Diagnostic accuracy of 18F-FAPI PET/MR compared to MR only in prediction/evaluation of response to neoadjuvant chemotherapy
PET/MRI data compared to clinical response to chemotherapy (cR), pathologic complete response (pCR) and residual cancer burden (RCB)
Time frame: From baseline to surgery (~3-6 months)
Diagnostic accuracy of 18F-FAPI PET/MR compared to standard CT/bone scintigraphy in staging of breast cancer
Comparison of detection rates by PET/MR data to standard CT/bone scintigraphy.
Time frame: Baseline
Diagnostic accuracy of 18F-FAPI PET/MR compared to CT/bone scintigraphy in detection of recurrence.
Comparison of detection rates by PET/MR data to standard CT/bone scintigraphy.
Time frame: Baseline
Diagnostic accuracy of 18F-FAPI PET/MR compared to 18F-FDG PET/CT.
Comparisons of consesus readings by radiologists and nuclear medcine physisians.
Time frame: Baseline
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