Impact of nasopharyngeal irradiation and gadolinium administration on changes in T1 signal intensity of the dentate nucleus in nasopharyngeal malignancy patients without intracranial abnormalities
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BackgroundIrradiation 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.PurposeTo explore how nasopharyngeal irradiation affected SI changes on unenhanced T1‐weighted imaging (T1WI) in the DN in nasopharyngeal malignancy (NPM) patients who presented with NIAs and who had multiple injection doses (IDs) of linear GBCAs.Study TypeSingle‐center, retrospective, case–control study.PopulationIn all, 132 subjects: 66 NPM patients, 66 matched controls.Field Strength/Sequence1.5T and 3T/T1WI, T2WI, and fluid‐attenuated inversion recovery (FLAIR).AssessmentRadiation 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 (Rchange) were compared.Statistical TestsShapiro–Wilk test, paired t‐test, independent t‐test, Mann–Whitney U‐test, Pearson and Spearman correlation.ResultsDN/CWMb ratios or Rchange from the NPM group were significantly higher than those from the control group (P < 0.001). No significant difference of DN/CWMa ratios was found between the two groups (P > 0.05). Positive correlations between Rchange, DN/CWMb ratio, and the number of IDs were found in both the NPM and control groups (P < 0.01). The overall changes of DN/CWMb ratio or Rchange between NPM and control groups were higher for the higher‐IDs subgroup (≥10) than for the lower‐IDs subgroup (<10).Data ConclusionNasopharyngeal irradiation appeared to increase SI in T1WI 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 Rchange and RDs to the DNs was found.Level of Evidence: 3Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:250–259.
