Magnetic resonance imaging of canine salivary glands after ductal ligation and stimulation by pilocarpine.

We performed magnetic resonance imaging in six dogs after submandibular ductal ligation on one side, followed by secretory stimulation with intraperitoneal injection of pilocarpine (5 mg/kg). On the images obtained after ductal ligation but before stimulation, there was no significant change in signal intensity on either side. After injection of pilocarpine the signal intensity of the ligated gland increased significantly (p less than 0.01) in T2-weighted images and nonsignificantly in inversion recovery images, and remained constant in T1-weighted images. Significant (p less than 0.01) volume increases of the glands after ligation and stimulation were measured for the T1, T2, and inversion recovery protocols. These findings likely reflect the retention of saliva caused by pilocarpine stimulation and the absence of drainage through the obstructed duct. The results indicate that the T2-weighted images obtained after pilocarpine stimulation may be useful for studying patients with disturbance of major salivary gland function and may provide an objective basis for the noninvasive diagnosis of unilateral stenosis.