Object: To explore factors determining the detection of total choline (tCho) by in vivo MR spectroscopy (MRS) in locally advanced breast cancer and to evaluate the ability of in vivo tCho to predict treatment response after one cycle of neoadjuvant chemotherapy (NAC).
Materials and methods: Breast cancer patients (N=40) scheduled for NAC were examined with an MR protocol including in vivo single voxel proton MRS, dynamic contrast enhanced MRI and diffusion weighted MRI. tCho was quantified based on the signal-to-noise ratio. The detection was considered positive with tCho signal-to-noise ratio≥2.
Results: tCho was detected in 60% of the patients. Excellent reliability in tCho (ICC=0.97, P<0.001) measurements was confirmed. The water/fat-ratio, tumor volume and distribution of Type II voxels (based on contrast uptake curve) were significantly higher in patients with positive choline detection. The probability of detecting tCho was higher in ER-negative patients. A significant decrease in tChoSNR was detected after treatment, but responders could not be distinguished from non-responders.
Conclusion: The use of in vivo MRS in breast cancer diagnosis and treatment monitoring should bring supplementary information to the standard MR imaging protocol. With the currently observed low choline detection rate, this is not the case, and technological challenges related to choline detection have to be resolved.