Impact of nasopharyngeal irradiation and gadolinium administration on changes in T1 signal intensity of the dentate nucleus in nasopharyngeal malignancy patients without intracranial abnormalities

BACKGROUND: Irradiation has been found to increase T₁ signal intensity (SI) of the dentate nucleus (DN) by accelerating the gadolinium deposition in patients after multiple gadolinium-based contrast agent (GBCA) administrations. Several reports have focused on this phenomenon in patients with brain tumors; however, data in patients receiving irradiation with no intracranial abnormalities (NIAs) are lacking. PURPOSE: To explore how nasopharyngeal irradiation affected SI changes on unenhanced T₁ -weighted imaging (T₁ WI) in the DN in nasopharyngeal malignancy (NPM) patients who presented with NIAs and who had multiple injection doses (IDs) of linear GBCAs. STUDY TYPE: Single-center, retrospective, case-control study. POPULATION: In all, 132 subjects: 66 NPM patients, 66 matched controls. FIELD STRENGTH/SEQUENCE: 1.5T and 3T/T₁ WI, T₂ WI, and fluid-attenuated inversion recovery (FLAIR). ASSESSMENT: Radiation doses (RDs) were calculated by a radiotherapy technician. SIs were measured by a radiologist. The DN-to-cerebellar white matter (CWM) SI ratios and their relative percentage change (R_change ) were compared. STATISTICAL TESTS: Shapiro-Wilk test, paired t-test, independent t-test, Mann-Whitney U-test, Pearson and Spearman correlation. RESULTS: DN/CWM _b ratios or R _change from the NPM group were significantly higher than those from the control group (P < 0.001). No significant difference of DN/CWM _a ratios was found between the two groups (P > 0.05). Positive correlations between R _change , DN/CWM _b ratio, and the number of IDs were found in both the NPM and control groups (P < 0.01). The overall changes of DN/CWM _b ratio or R _change between NPM and control groups were higher for the higher-IDs subgroup (≥10) than for the lower-IDs subgroup (<10). DATA CONCLUSION: Nasopharyngeal irradiation appeared to increase SI in T₁ WI in NPM patients with NIAs and repeated GBCA administrations relative to control patients who also underwent GBCA administrations, especially when IDs ≥10. However, no significant association between R _change and RDs to the DNs was found. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:250-259.