Page 119 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

PSMA PET/CT: as a tool to assess and guide salivary gland irradiation
and radiotherapy dose administration. Xerostomia was scored according to the Common Terminology Criteria for Adverse Events version 4 (CTCAE v4).
Results
In case A, PSMA PET/CT showed significantly decreased ligand uptake in the irradiated area, suggesting extensive damage to the left submandibular gland and caudal part of the left parotid gland which received 70 Gy (figure 2). The sublingual glands which received 46 Gy showed partial loss of uptake. All other glands showed normal uptake, with standard uptake values (SUV) comparable to the earlier described values for healthy salivary glands [9]. Clinically there had been grade II xerostomia after treatment, but this had resolved completely at the time of imaging (12 months after RT).
In case B, PET/CT showed loss of PSMA-ligand uptake along the posterior pharyngeal wall glands and in the deep lobe of the left parotid gland, all of which received 70Gy (figure 3). All other gland locations showed normal uptake. Patient reported persistent grade II xerostomia at the time of imaging (11 months after RT).
In case C, PSMA PET/CT showed complete loss of signal in all major and minor 7 salivary gland locations (figure 4), except for notably high uptake in the area of the
mucosal lip glands that had not been irradiated. At the time of imaging (240 months
after RT) patient reported grade II xerostomia, but with sufficient salivation in the
ventral part of the mouth for normal speech and intake and without the need for artificial saliva or other measures.
Figure 2: Case A. Coronal slices of radiotherapy dose distribution at the level of the oral cavity (A) and parotid glands (B). Coronal maximum intensity projection of PSMA PET (C), showing the correlation between dose distribution and reduced PSMA uptake in salivary glands: left parotid gland, left submandibular gland, and both sublingual glands (green arrows). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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