Purpose: To report the feasibility and preliminary results of a prospective clinical trial sparing salivary duct containing stem cells with MRI sialography.
Methods: Seventeen patients were prospectively enrolled to receive pre-treatment MRI sialograms. One patient was excluded due to baseline xerostomia yielding 16 patients for analysis. MRI sialograms were rigidly fused to patientsâ€™ CT simulation. The parotid and submandibular salivary ducts were delineated on MRI and transferred to the CT simulation. Salivary ducts were then maximally spared during radiotherapy planning using Sun Nuclearâ€™s Feasibility DVH. Visibility of the salivary ducts were quantified using a previously utilized visualization score. Mean doses to each salivary gland, entire salivary ducts, intra-glandular ducts, and region of first branching (nidus) were quantified. Physician and patient reported symptom assessments were recorded at 6mo post treatment for five patients.
Results: 31/32 and 9/10 parotid ducts and received the maximum duct visualization score pretreatment and at 6months post treatment, respectively. One gland did not have secondary branching visible pretreatment nor post treatment. The mean dose to the contralateral parotid, entire salivary duct, intra-glandular ducts and nidus were 21.5, 9.7, 11.5, and 9.2Gy, respectively. The mean dose to the ipsilateral parotid, entire salivary duct, intra-glandular ducts, and region of first branching were 39.4, 14.1, 22.2, and 18.3Gy, respectively. 13/16 in-gland contralateral parotid ducts received mean doses less than 11Gy and 8/16 in-gland ipsilateral parotid ducts received mean doses less than 15Gy. Substantial sparing of the submandibular ducts was not possible due to the proximity to the PTV. Physician and patient reported symptom assessments at 6months post-treatment are reported in Table 1.
Conclusion: It is feasible to use MRI sialography to visualize and dosimetrically spare salivary ducts within the parotid glands to doses <15Gy. Additional, follow-up is needed to determine if this technique improves patient symptoms. NCT03418792