Early evaluation of radiation-induced parotid damage with diffusion kurtosis imaging: a preliminary study

Abstract

Background Radiation-induced parotid gland damage is a common complication of radiotherapy (RT) in patients with nasopharyngeal carcinoma (NPC), which always causes xerostomia, dysphagia, dental caries, and even sleep disorders. Early evaluation of radiation-induced parotid damage is required to facilitate early interventions. Purpose To early-evaluate radiation-induced parotid damage using diffusion kurtosis imaging (DKI) in patients with NPC undergoing RT. Material and Methods Thirty-two patients with NPC underwent DKI for parotid glands pre-RT (two weeks before RT), mid-RT (five weeks after RT began), and post-RT (four weeks after RT). Parotid volume, apparent diffusion coefficient (ADC), corrected diffusion coefficient (D), excess diffusion kurtosis coefficient (K) values, mean radiation dose, and xerostomia degrees were recorded and analyzed. Results During RT, parotid ADC (change rates = 41.3 ± 25.2% at mid-RT, 70.8 ± 34.3% at post-RT) and D (change rates = 41.9 ± 25.2% at mid-RT, 63.2 ± 30.2% at post-RT) increased, while parotid volume (atrophy rates = 31.5 ± 7.9% at mid-RT, 30.6 ± 10.3% at post-RT) and K (change rates = -17.8 ± 11.0% at mid-RT, -29.8 ± 9.0% at post-RT) decreased significantly (all P < 0.001). At post-RT, the change rate of parotid D values was significantly positively correlated with the mean radiation dose ( r = 0.455, P < 0.001). Parotid ADC, D, and K values showed excellent intra- and inter-observer agreement (intraclass correlation coefficient = 0.946-0.985). Conclusion Radiation-induced parotid damage in patients with NPC undergoing RT could be effectively evaluated by DKI in the early stage.

Application of Diffusion Kurtosis Imaging in Evaluating Acute Xerostomia in Nasopharyngeal Carcinoma Treated With Induction Chemotherapy Plus Concurrent Chemoradiotherapy

“…The study found that MD of bilateral PG, SMG, and SLG at mid-RT (t3) and post-RT (t4) significantly increased while MK decreased compared with that of pre-RT, and the comparison between mid- and post-RT was also significant. The trend of MD is in accord with the change in ADC that had been reported in a previous study ( 10 ), which also corroborates the research on evaluation of RT-induced salivary gland damage ( 21 , 24 , 25 ). The increase in MD suggested increased water diffusivity as a result of RT-induced apoptosis of acinar cells and decrease in tissue cellular packing density ( 6 , 10 , 22 ) while reduced MK depends on the structural complexity of the glands ( 20 , 21 ).…”

“…The trend of MD is in accord with the change in ADC that had been reported in a previous study ( 10 ), which also corroborates the research on evaluation of RT-induced salivary gland damage ( 21 , 24 , 25 ). The increase in MD suggested increased water diffusivity as a result of RT-induced apoptosis of acinar cells and decrease in tissue cellular packing density ( 6 , 10 , 22 ) while reduced MK depends on the structural complexity of the glands ( 20 , 21 ). Decreased diffusion kurtosis together with increased mean diffusivity may indicate increased extracellular space within the voxel of interest.…”

“…Diffusion kurtosis imaging (DKI), an advanced diffusion technique based on non-Gaussian diffusion distribution assumption, is of capacity in reflecting the true water diffusion in vivo ( 20 ). In recent years, the application of DKI indeed provide an opportunity to get further insights into the microstructure change of irradiated salivary glands without invasiveness ( 21 ). However, the techniques merely focused on investigating PG injury, and there had been no study on evaluating SMG and SLG by DKI ever before.…”

The Role of Patient- and Treatment-Related Factors and Early Functional Imaging in Late Radiation-Induced Xerostomia in Oropharyngeal Cancer Patients

“…The performance of the models may be underestimated by the fact that they were evaluated on the internal test set after a stratified 5-fold cross-validation, which may not be representative of the entire data set due to the small sample size. We did not include ADC/D t histogram analysis, though it was suggested by others [ 45 ] that early changes in the highest ADC percentiles correlated to Grade 2 xerostomia and could be clinically useful. Future investigations will include the role of D t histogram analysis in particular, with the aim of improving the sensitivity of the classification model.…”

Radioiodine therapy induced sialadenitis versus chronic idiopathic sialadenitis—Presentation and outcomes

“…Toxicity to the salivary glands is dose‐dependent, and although toxicity related to lower doses (20–30 Gy) is reversible, higher doses (>50 Gy) carry the potential for irreversible damage 9 . The most susceptible to prolonged damage are the parotid glands 10,11 . Symptoms can be debilitating and may significantly affect quality of life, including chronic pain, constant or recurrent swelling of one or more glands, and xerostomia that causes odynophagia and dysphagia.…”