Improved tissue sodium concentration quantification in breast cancer by reducing partial volume effects: a preliminary study
Introduction: In sodium (23Na) magnetic resonance imaging (MRI), partial volume effects (PVE) are one of the most common causes of errors in the in vivo quantification of tissue sodium concentration (TSC). Advanced image reconstruction algorithms, such as compressed sensing (CS), have the potential to reduce PVE. Therefore, we investigated the feasibility of using CS-based methods to improve image quality and TSC quantification accuracy in patients with breast cancer. Subjects and methods: In this study, three healthy participants and 12 female participants with breast cancer were examined on a 7T MRI scanner. 23Na-MRI images were reconstructed using weighted total variation (wTV), directional total variation (dTV), anatomically guided total variation (AG-TV) and adaptive combine (ADC) methods. The consistency of tumor volume delineations based on sodium data was assessed using the Dice score, and TSC quantification was performed for various image reconstruction methods. Pearsons correlation coefficients were calculated to assess the relationships between wTV, dTV, AG-TV, and ADC values. Results: All methods provided breast MRI images with well-preserved sodium signal and tissue structures. The mean Dice scores for wTV, dTV, and AG-TV were 65%, 72%, and 75%, respectively. Average TSC values in breast tumors were 61.0, 72.0, 73.0, and 88.0 mmol/L for wTV, dTV, AG-TV, and ADC, respectively. A strong negative correlation was observed between wTV and dTV (r = -0.78, 95% CI [-0.94, -0.31], p = 0.0076) and a strong positive correlation between dTV and AG-TV (r = 0.71, 95% CI [0.16, 0.92], p = 0.0207) was found. Conclusion: The results of this study showed that differences in tumor appearance and TSC estimations may depend on the type of image reconstruction and the parameters used. This is most likely due to differences in their ability to reduce PVE.