Diagnostic Accuracy of Ultrasonic Histogram Features to Evaluate Radiation Toxicity of the Parotid Glands

Abstract

Rationale and Objectives To investigate the diagnostic accuracy of ultrasound histogram features in the quantitative assessment of radiation-induced parotid gland injury and to identify potential imaging biomarkers for radiation-induced xerostomia (dry mouth)—the most common and debilitating side effect after head-and-neck radiotherapy (RT). Materials and Methods Thirty-four patients, who have developed xerostomia after RT for head-and-neck cancer, were enrolled. Radiation-induced xerostomia was defined by the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer morbidity scale. Ultrasound scans were performed on each patient’s parotids bilaterally. The 34 patients were stratified into the acute-toxicity groups (16 patients, ≤3 months after treatment) and the late-toxicity group (18 patients, >3 months after treatment). A separate control group of 13 healthy volunteers underwent similar ultrasound scans of their parotid glands. Six sonographic features were derived from the echo-intensity histograms to assess acute and late toxicity of the parotid glands. The quantitative assessments were compared to a radiologist’s clinical evaluations. The diagnostic accuracy of these ultrasonic histogram features was evaluated with the receiver operating characteristic (ROC) curve. Results With an area under the ROC curve greater than 0.90, several histogram features demonstrated excellent diagnostic accuracy for evaluation of acute and late toxicity of parotid glands. Significant differences (P < .05) in all six sonographic features were demonstrated between the control, acute-toxicity, and late-toxicity groups. However, subjective radiologic evaluation cannot distinguish between acute and late toxicity of parotid glands. Conclusions We demonstrated that ultrasound histogram features could be used to measure acute and late toxicity of the parotid glands after head-and-neck cancer RT, which may be developed into a low-cost imaging method for xerostomia monitoring and assessment.

Apparent diffusion coefficient histogram analysis can evaluate radiation-induced parotid damage and predict late xerostomia degree in nasopharyngeal carcinoma

“…SD values also increased from time point 2 to 3, indicating more heterogeneity due to fibrosis and repair of parotid glands four months after radiotherapy [ 23 ]. Yang et al also reported that the 3-dB bandwidth further widened from acute toxicity (with 3 months after radiotherapy) to late toxicity of parotid glands (beyond 3 months after radiotherapy), indicating a more heterogeneous texture of parotid parenchyma [ 25 ].…”

Current State of Knowledge on Salivary Gland Cancers

“…Yang et al took an additional step to quantitatively model sonogram images to identify patients with acute versus late toxicities. 85…”

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

“…Computed tomography (CT) can show morphological changes of the parotid glands after radiotherapy, but CT brings additional radiation exposure (8,9). Ultrasonography (US) can also been used to evaluate radiation-induced parotid damage, yet US depends on the settings of the scanner and the experience of the operator (8,10). Magnetic resonance imaging (MRI) presents an ideal modality to evaluate radiation-induced parotid damage due to its excellent soft tissue contrast (11).…”