Added value of maximum standardized uptake value and diffusion-weighted imaging in s taging of high risk breast cancer patients using simultaneous 18 F-flurodeoxyglucose positron emission tomography and magnetic resonance imaging.

BACKGROUND

Accurate staging is essential in high risk breast cancer to guide management. While flurodeoxyglucose (FDG) PETCT is well established, limited data exist on the cancers role of maximum standardized uptake value (SUV max ) and diffusion-weighted imaging (DWI), especially with limited access to positron emission tomography and magnetic resonance imaging (PETMR). This study evaluates the diagnostic performance of PETMR and correlation between SUV max and apparent diffusion coefficient (ADC) values in staging these patients.

METHODS

This retrospective study includes 76 biopsy-confirmed treatment-naïve high risk breast cancer patients (triple negative breast cancer and non-triple negative breast cancer) who underwent FDG PETMR (2021-2024). A total of 965 lesions were analysed. Lesion detection, quantitative parameters, and diagnostic performance were assessed, including receiver operating characteristic analysis of SUV-ADC biomarkers.

RESULTS

SUV max showed an inverse correlation with ADC mean ( r  = -0.41) and ADC min ( r  = -0.47), strongest in primary breast tumours and skeletal metastases. The SUV max /ADC min ratio effectively graded tumours and correlated with Ki-67 ( r  = 0.55). FDG PET demonstrated higher specificity (87.8%) than DWI (82.7%), while DWI was more sensitive for detecting small lesions. False positives and false-negative lesions were identified by correlating PET and DWI findings with histopathology (wherever available) or using follow up imaging.

CONCLUSION

Simultaneous PETMR is promising for accurate staging of high risk breast cancer. PET demonstrates higher specificity, whereas DWI improves sensitivity for detecting smaller lesions, particularly in liver, brain, and lungs. A combined FDG PET DWI approach enhances overall diagnostic accuracy and improves lesion characterization and staging. Additionally, the combination of SUV max and Ki-67 provides a reliable indicator of tumour aggressiveness.