The extent of unnecessary tooth loss due to extractions prior to radiotherapy based on radiation field and dose in patients with head and neck cancer.

BACKGROUND AND PURPOSE: Prior to radiotherapy (RT), teeth with poor prognosis that pose a risk for post-RT osteoradionecrosis (ORN) are removed. To allow enough time for adequate wound healing prior to RT, decisions are made based on the estimated radiation dose. This study aimed to gain insight into (1) the overall number of teeth extracted and (2) the patient and tumor characteristics associated with the number of redundantly extracted teeth. MATERIALS AND METHODS: Patients with head and neck cancer (HNC), treated with RT between 2015 and 2019, were included in this cross-sectional study. For each extracted tooth the radiation dose was calculated retrospectively. The cut-off point for valid extraction was set at ≥ 40 Gy in accordance with the national protocol. Potential factors for doses ≥ 40 Gy were identified, including age, sex, tumor location, tumor (T) and nodal stage (N), overall tumor stage and number of teeth extracted. RESULTS: A total of 1759 teeth were removed from 358 patients. Of these 1759 teeth, 1274 (74%) appeared to have been removed redundantly, based on the mean dose (Dmean) of < 40 Gy. Using the maximum dose (Dmax) of < 40 Gy, 1080 teeth (61%) appeared to have been removed redundantly. Tumor location and N-classification emerged as the most important associative variables in the multivariable regression analysis. CONCLUSION: To our knowledge this is the first study to provide insight into the amount of teeth redundantly extracted prior to RT and represents a step forward in de-escalating the damage to the masticatory system prior to RT.

Detection of Bone Marrow Edema in the Head and Neck With Dual-Energy CT: Ready for Clinical Use?

OBJECTIVE. The aim of this study is to evaluate the ability of dual-energy CT (DECT) to identify bone marrow edema (BME) in the head and neck region in comparison with MRI as the standard of reference. MATERIALS AND METHODS. A total of 33 patients who underwent imaging between February 2016 and February 2018 were included in this retrospective study. All patients underwent both DECT and MRI for head and neck abnormalities. Two radiologists independently visually assessed virtual noncalcium (VNCa) reconstructions with color-coded maps for the presence of BME. STIR or T2-weighted MRI reconstructions with fat suppression were used as the standard of reference for BME. Subjective quality assessment and severity of metal artifacts were scored on both imaging modalities. RESULTS. BME was detected in 18 patients on DECT compared with 20 patients on MRI. Most BME seen on DECT was located in the mandible. VNCa DECT images had a sensitivity, specificity, positive predictive value, and negative predictive value for BME of 85%, 92%, 94%, and 80% respectively, using MRI as the reference. The quality of the images was rated as excellent to moderate in 94% of the patients for VNCa DECT compared with 82% of the patients for MRI, but this difference was not statistically significant. Significantly more metal artifacts were scored on the mixed DECT images than on the MR images, but these artifacts did not interfere with diagnosis. CONCLUSION. BME detection in the head and neck region seems possible with VNCa DECT images and has the potential to provide an alternative for MRI in clinical practice.

Dual-Energy CT in Head and Neck Imaging.

PURPOSE OF REVIEW: To explain the technique of Dual-energy CT (DECT) and highlight its applications and advantages in head and neck radiology. RECENT FINDINGS: Using DECT, additional datasets can be created next to conventional images. In head and neck radiology, three material decomposition algorithms can be used for improved lesion detection and delineation of the tumor. Iodine concentration measurements can aid in differentiating malignant from nonmalignant lymph nodes and benign posttreatment changes from tumor recurrence. Virtual non-calcium images can be used for detection of bone marrow edema. Virtual mono-energetic imaging can be useful for improved iodine conspicuity at lower keV and for reduction of metallic artifacts and increase in signal-to-noise ratio at higher keV. SUMMARY: DECT and its additional reconstructions can play an important role in head and neck cancer patients, from initial diagnosis and staging, to therapy planning, evaluation of treatment response and follow-up. Moreover, it can be helpful in imaging of infections and inflammation and parathyroid imaging as supplementary reconstructions can be obtained at lower or equal radiation dose compared with conventional single energy scanning.