PURPOSE: This study evaluated salivary gland function using MR cine sialography (MRCS) based on the time-spatial labeling inversion pulse (Time-SLIP) technique combined with a deep learning reconstruction-based denoising method (dDLR). Bilateral salivary flow from the submandibular glands (SMGs) and parotid glands (PGs) was visualized, and its correlation with whole-saliva volume was examined. METHODS: Optimal MRCS parameters were identified, and imaging was performed in 11 healthy volunteers. Correlations between salivary flow on MRCS and unstimulated whole-saliva volume (UWS) and stimulated whole-saliva volume (SWS), as well as side-to-side differences, were analyzed. UWS was obtained using the spitting method, and SWS was obtained using the gum-chewing test. Salivary-flow distance was defined as the length from the labeling position to the point where the labeled saliva signal became indistinguishable from background signal. Spearman's rank correlation coefficients (ρ) were calculated to evaluate the association between whole-saliva volume and MRCS, and Wilcoxon's signed-rank test was used to assess side-to-side differences. RESULTS: Correlation coefficients between MRCS and whole-saliva volume were as follows: under unstimulated conditions, SMG ρ = 0.825, PG ρ = -0.05, SMG + PG ρ = 0.802; under stimulated conditions, SMG ρ = 0.606, PG ρ = 0.72, and SMG + PG ρ = 0.820. Strong correlations (ρ > 0.8) were observed for SMG and SMG + PG under unstimulated conditions and for SMG + PG under stimulation. No significant overall side-to-side differences were found except for PG under stimulation (P = 0.016). However, several individuals showed notable side-to-side differences, underscoring the value of bilateral imaging. CONCLUSION: Bilateral SMG and PG salivary flows obtained using MRCS with dDLR showed strong correlations with UWS and SWS. These findings suggest that MRCS is a promising noninvasive method for assessing salivary volume and supports both separate and combined evaluation of SMG and PG function.
Koizumi et al. (Thu,) studied this question.