The application of FCH PET in breast cancer diagnosis has not been reported.

We hypothesize that FCH reveals choline metabolic profiles of breast cancers, and shows the similar pathophysiological mechanism to choline on proton MRS, and our study goals are:

1. To investigate and compare the diagnostic performance of proton MRS and FCH PET for localized findings on mammography and breast ultrasound.
2. To investigate whether FCH PET findings are correlated with choline signals on proton MRS.
3. To evaluate if choline, water and lipid signals on proton MRS, FCH PET are associated with factors related to clinical outcome and prognosis- that is, molecular markers, tumor staging, histologic grade of breast cancers.
4. For localized advanced breast cancer, to investigate the treatment response to NAC using proton MRS and FCH PET, and to evaluate which modality is more sensitive.
5. To investigate the usefulness of FCH PET for whole body staging for breast cancer patients.

In recent years, the application of 18F-FDG PET (positron emission tomography) and MRI for breast lesion diagnosis was emerging. Imbriaco et al compared the diagnostic performance of 18F-FDG PET and MRI for suspicious breast lesions, with PET showing a sensitivity of 80% and specificity 100%; and MRI revealed a sensitivity of 95% and specificity of 98%. Lim et al studied 18F-FDG PET-CT with MRI to monitor treatment response for breast cancer patients receiving NAC, with a sensitivity 70% and specificity 72%, and can detect the treatment response earlier than conventional imaging.

However, 18F-FDG is not tumor specific, and searching for an alternative tracer agent as a tumor biomarker is necessary. 18F-Fluorocholine (FCH), a choline analog, was used for diagnosis of prostate cancer, hepatocellular carcinoma (HCC), bronchioloalveolar carcinoma, brain tumor, since malignant tumors show higher choline metabolites than benign lesions; it was reported that FCH PET showed higher sensitivity (88-94%) than 18F-FDG PET (59-68%) in detecting HCC. FCH PET was used for staging for prostate cancer, with FCH PET-CT can provide sufficient information for management with an accuracy of 88%.

Inclusion Criteria:

• Women aged 20-75 years old.
• with localized findings on mammography or breast ultrasound in recent 3 months and who will receive breast biopsy or excision for the findings; or with recently diagnosed LABC who will receive NAC.

Exclusion Criteria:

• unable to cooperate with the examinations
• pregnant or planning to be pregnant
• estimated GFR (eGFR) < 60 ml/min/1.73m2 or with recent acute renal failure, past history of renal dialysis.
• Past history of claustrophobia
• Past history of anaphylactoid reactions to MRI contrast agents or PET tracer agents.
• with cardiac pacemaker, aneurysmal clip, mechanical valve replacement, recently applied coronary artery stent (<2 months).
• Past history of breast cancer or other malignancy (treated within 5 years).
• lactating.