The role of magnetic resonance imaging and magnetic resonance sialography in the evaluation of salivary sialolithiasis: radiologic-endoscopic correlation

Introduction
To evaluate the role of magnetic resonance imaging (MRI) and MR sialography in salivary gland calculi in correlation with sialendoscopy.

Material and methods
In this prospective study, pre-therapeutic MRI was performed for patients with clinically suspected sialolithiasis. In addition, sialendoscopy with or without surgery was performed. The detectability, number, size, and location of calculi (distance of obstruction from the ostium and masseter line) and the condition of the main duct at MRI were reported. Agreement between the 2 readers was confirmed for all MRI findings. Data regarding the detectability, number, and size of calculi were correlated with endoscopy.

Results
There was excellent agreement between the 2 readers regarding the detection and number of calculi at MR sialography (κ = 1, p < 0.001). As regards MRI measurements, excellent interclass correlation was found between the 2 readers regarding size of calculi, distance of calculi from the ostium, and distance from the masseter line (κ = 0.98, 0.98, 0.97, respectively; p < 0.001). In correlation with sialendoscopy, MRI was false negative in 1 patient, and it missed 1 calculus in 3 patients with multiple calculi. There was no statistically significant difference between the size of calculi detected by MRI and true size of calculi retrieved by sialendoscopy.

Conclusions
MR sialography is an accurate modality for diagnosis of the presence, size, and location of sialolithiasis and offers accurate ductal mapping for sialendoscopists.