doi:10.1016/j.ijrobp.2007.01.062 CLINICAL INVESTIGATION Head and Neck 3D MR SIALOGRAPHY AS A TOOL TO INVESTIGATE RADIATION-INDUCED XEROSTOMIA: FEASIBILITY STUDY ELEFTHERIA ASTREINIDOU,PH.D.,* J UDITH M. ROESINK, M.D., PH.D.,* CORNELIS P. J. RAAIJMAKERS,PH.D.,* LAMBERTUS W. BARTELS,PH.D., † THEO D. WITKAMP, M.D., † JAN J. W. LAGENDIJK,PH.D.,* AND CHRIS H. J. TERHAARD, M.D., PH.D.* *Department of Radiation Oncology, and † Image Sciences Institute, Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands Purpose: To evaluate whether magnetic-resonance (MR) sialography can be used to investigate radiation- induced xerostomia. Preradiotherapy (pre-RT) and postradiotherapy (post-RT) MR sialographic images of the major salivary ducts (parotid and submandibular) were compared. Methods and Materials: Magnetic-resonance sialography was performed pre-RT, and 6 weeks and 6 months post-RT on 9 patients with T1-4N0-2M0 naso- or oropharyngeal tumors, on a 1.5-T MR scanner. Patients were positioned in the scanner, using a radiotherapy immobilization mask. Image registration of the MR sialograms pre- and post-RT with each other and with the CT and consequently the dose distribution was performed. A categorical scoring system was used to compare the visibility of ducts pre-RT and post-RT. Results: Good-quality MR sialographic images were obtained, and image registration was successful in all cases. The visibility score of the parotid ducts and submandibular ducts was reduced at 6 weeks post-RT, which means that the full trajectory of the salivary ducts, from the intraglandular space to the mouth cavity, was only partially visualized. For some of the parotid ducts, the visibility score improved at 6 months post-RT, but not for the submandibular ducts. The mean dose for the parotid glands was 35 Gy (1 standard deviation [SD] 3 Gy), and for the submandibular glands it was 62 Gy (SD, 8 Gy). Conclusion: Three-dimensional MR sialography is a promising approach for investigating xerostomia, because radiation-induced changes to the saliva content of the ducts can be visualized. © 2007 Elsevier Inc. 3D MR sialography, Xerostomia, Salivary glands, IMRT, Head-and-neck radiotherapy. INTRODUCTION Salivary dysfunction is a prevalent side effect suffered by patients receiving head-and-neck radiotherapy (RT). Lack of saliva production results in impaired quality of life, and can be permanent (1–6). The elucidation of the exact mech- anism of radiation damage to the salivary glands has been the subject of many studies (7). It was suggested that damage to the acinar and ductal systems is the main cause of salivary-gland dysfunction in humans after RT (8). It was also suggested that edematous stenosis of the major salivary ducts takes place progressively during irradiation, leading to symptoms of acute sialadenitis with an excretory obstacle (9). In these studies, either changes in saliva and serum electrolyte levels were investigated, or salivary-gland scin- tigraphy with 99m Tc-pertechnetate was performed. How- ever, neither these nor other studies systematically investi- gated the salivary-duct system in humans after RT. In this pilot study, we aimed to do that, by using a noninvasive, novel imaging approach, magnetic-resonance (MR) sialog- raphy, for the first time. Magnetic-resonance sialography is an imaging technique whereby static fluids or slowly flowing fluids in the body, such as saliva, are imaged as high-signal-intensity bright structures against a dark background (10). In other words, the salivary ducts can be imaged because they contain saliva. Saliva itself is the contrast medium. This property alone makes MR sialography an attractive method to use when studying hyposalivation, as in cases of radiation- induced xerostomia. Magnetic-resonance sialography was already proven to be a useful imaging technique for other salivary-gland and duct disorders such as sialolithiasis and Sjögren’s syndrome (11–15). The conventional method of visualizing the ductal system is by X-ray sialography. This two-dimensional (2D) tech- nique requires injection of contrast medium and manual Reprint requests to: Eleftheria Astreinidou, Ph.D., Depart- ment of Radiation Oncology, University Medical Center Utre- cht, Huispost Q00.118, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. Tel: (+31) 30-2503035; Fax: (+31) 30-2581226; E-mail: E.Astreinidou@umcutrecht.nl This research was supported by the Dutch Cancer Society (Grant number UU 2001–2468). Conflict of interest: none. Received April 13, 2006, and in revised form Jan 8, 2007. Accepted for publication Jan 30, 2007. Int. J. Radiation Oncology Biol. Phys., Vol. 68, No. 5, pp. 1310 –1319, 2007 Copyright © 2007 Elsevier Inc. Printed in the USA. All rights reserved 0360-3016/07/$–see front matter 1310