Abstract PO-056: Sonographic and photoacoustic monitoring of radiation-induced parenchymal and vascular injury to salivary glands

Abstract

Abstract Salivary gland dysfunction is a common side effect of radiation therapy (RT) in patients with head and neck cancer and is a consequence of direct damage to glandular parenchyma along with inflammatory changes and vascular injury following radiation. However, dynamic functional imaging of changes in salivary gland vascularity and oxygenation following RT has not been previously reported. Here, we employed bimodal photoacoustic imaging (PAI) with co-registered ultrasound (US) to non-invasively monitor radiation-induced parenchymal and vascular injury to salivary glands in vivo. Experimental imaging studies revealed parenchymal damage on B-mode US and early increase in vascular resistance on contrast-enhanced US (within 24h following radiation). Notably, this was accompanied by a reduction in oxygen consumption of salivary glands on dynamic PAI following parasympathetic stimulation with pilocarpine. Temporal kinetics of radiation-induced vascular injury was dependent on the host immune status and correlates with stimulated salivary secretion. These findings demonstrate the ability of US-PAI to monitor the dynamic changes in neurovascular coupling of salivary glands following radiation injury and highlight its potential utility to identify drugs or therapeutic approaches that could protect or mitigate radiation-induced vascular damage. Citation Format: Eftekhar Rajab Bolookat, Vui King Vincent-Chong, Anurag K. Singh, Mukund Seshadri. Sonographic and photoacoustic monitoring of radiation-induced parenchymal and vascular injury to salivary glands [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-056.