Treatment Planning Using FDG-PET to Optimize Parotid Gland Sparing Before and During Chemoradiation for Head-and-Neck Cancer

surgical only (SX), chemo-radiation (CXRT), and mixed therapy. Coordinates mapping swallowing structures were collected at maximum and minimum swallow excursion points for the hyoid, larynx, and pharynx. Canonical variate analysis was performed to determine shape changes associated with HNC treatment paradigms. Indicators of swallowing safety and efficiency were compared by group using the penetration aspiration score (PAS) and normalized residue ratio scale (NRRS). Results: A canonical variate analysis of coordinates by swallowing excursion and treatment group resulted in eigenvalues that accounted for 71.7% of the variance by swallow function and 22.5% by treatment group. A significant difference in shape change was noted by discriminate analysis between SX (nZ17) and CXRT (nZ12) treatment groups (DZ 2.51, p< .0001). Eigenvectors associated with swallowing indicated increased extension of the head and neck in the SX group and reduced pharyngeal shortening in CXRT group. No significant differences were noted in airway invasion and pharyngeal clearance (PAS, NRRSp, NRRSv) between SX and CXRT groups. Conclusions:Morphological changes in the swallowing structure varied by treatment paradigm with SX and CXRT comprising two ends of the shape change spectrum. Changes indicate compensatory movement of the head and neck in the SX cohort and reduced function of the long pharyngeal muscles in CXRT cohort. While changes in the functional anatomy of swallowing between treatment groups are significant, indicators of swallowing safety and efficiency, penetration-aspiration and residue, are not indicating adaptation to structural insults. Morphometric analysis of swallowing function is a novel approach to evaluating what structural insults are associated with treatment paradigms. These methods coupled with swallowing outcome measurements may provide better insight into dysphagias associated with head and neck cancer treatment. Author Disclosure: J. Blair: None. C.Z. Johnson: None. S.L. Rice: None. B. Martin-Harris: None. W.G. Pearson: None.