Magnetic resonance imaging at 3.0T for submandibular gland sparing radiotherapy.
OBJECTIVE
Besides sparing the parotid gland, sparing the submandibular gland is considered to be important in preventing xerostomia in head-and-neck cancer patients. Delineation of the submandibular gland at CT, and even on T(1)- and T(2)-weighted MR images, is difficult, due to low contrast with the surrounding tissues. MR sialography might be used for delineation.


METHODS
Sixteen oropharyngeal cancer patients received a CT and MRI exam as part of the standard treatment imaging protocol. Patients were scanned in their five-point RT immobilization mask. The MRI exam included T(1)- and T(2)-weighted MRI scans and an MR sialography scan. Thirty submandibular glands were delineated on only CT, on the combined CT and T(1)- and T(2)-weighted MRI scans and on all MR images. A Wilcoxon signed-rank test was performed to test if the delineated volumes were significantly different.


RESULTS
The delineated volume of the submandibular gland was 7.3mL in the CT-delineation, 7.1mL in the CT/MRI-delineation and 8.1mL in the MRI-delineation. The MRI-delineation was significantly larger than the other delineations (p<0.001). The differences were mainly located in the cranial direction.


CONCLUSIONS
The delineation of the submandibular gland was improved in the cranial direction by using T(1)- and T(2)-weighted MRI and MR sialography, compared to the other delineations.
Houweling
Antonetta C
AC
Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands. A.Houweling@umcutrecht.nl
van den Berg
Cornelis A T
CA
Roesink
Judith M
JM
Terhaard
Chris H J
CH
Raaijmakers
Cornelis P J
CP
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008279:Magnetic Resonance Imaging; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D012796:Sialography; D013363:Submandibular Gland / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed