Assessment of hyperbaric oxygenation treatment response in post-radiation salivary glands by T2 mapping

Abstract

The study was designed to evaluate the influence of hyperbaric oxygenation (HBO) therapy on the salivary gland status in patients with head and neck tumours who had undergone radiation therapy. Its effects were monitored by magnetic resonance imaging (MRI) using the T₂ mapping method on a 3T MRI clinical system. Twenty patients with radiation doses from 50 to 80 Gy were included as well as 20 gender- and age-matched controls. The initial measurements were performed at baseline before the first HBO therapy (40.2 ± 20 months after radiation therapy), and the second, after 20 daily HBO therapies at 2.5 ATA (absolute atmosphere) in which patients breathed 100% oxygen for 90 minutes each day. Complimentary to both MRI measurements, salivary flow, buffer capacity, and pH were also determined. The mean T₂ values obtained from T₂ maps on the radiation side decreased from 121 ± 20 msec to 113 ± 16 msec at the end of HBO therapy (p=0.002), but no change was observed on the contralateral side. In addition, a negative Pearson correlation coefficient was observed between the mean T₂ value in the parotid gland on the radiation side and unstimulated saliva pH (R=-0.647, p=0.004) as also stimulated salivary flow (R=-0.592, p=0.01). The study confirmed that T₂ mapping of salivary glands can be used to reliably quantify their response to HBO therapy; hence, it has the potential to be a complementary diagnostic tool in the assessment of salivary gland status in patients with hyposalivation.

Keywords: salivary glands; MRI; T₂ mapping; hyperbaric oxygenation therapy