Quantitative MRI in the assessment of clival invasion in locally advanced nasopharyngeal carcinoma.

OBJECTIVE

This study assesses the value of quantitative magnetic resonance imaging (qMRI) in evaluating clival invasion (CI) and monitoring therapeutic response in locally advanced nasopharyngeal carcinoma (LA-NPC). It also investigates the relationship between qMRI parameter changes in CI and regression of nasopharyngeal soft-tissue invasion.

METHODS

In this prospective study, fifty-five LA-NPC patients with CI from a single-center underwent qMRI at baseline (t0), pre-radiotherapy (t1), mid-radiotherapy (t2), and post-radiotherapy (t3). T1, T2, and T2* mappings were measured in manually delineated volumes of interest. Patients were categorized into complete response (CR) and non-CR groups based on nasopharyngeal soft tissue tumor regression per RECIST 1.1. The cervical vertebrae served as self-controls.

RESULTS

At baseline, T1, T2, and T2* mapping values were significantly higher in clival invasion than in normal cervical vertebrae (p < 0.001). During treatment, the CR group (87.3%) exhibited marked decreases in T1 values (from 841.30 [IQR:521.31] ms at baseline to 587.61 [IQR: 187.54] ms at post-RT; p<0.001) and T2* values (from 7.27 [IQR: 5.28] ms to 4.86 [IQR: 3.48] ms; p<0.001), accompanied by a significant increase in T2 values (from 89.83 [IQR: 18.25] ms to 99.79 [IQR: 12.10] ms; p<0.001), whereas the non-CR group showed no significant alterations in T1 and T2 mapping values (p > 0.05). Notably, there were no significant differences in T1, T2, and T2* mapping values between t2 and t3 in the CR group (p > 0.05). Furthermore, differences between CI and cervical vertebrae measurements (ΔT1, ΔT2, ΔT2*) diminished in the CR group during treatment (p < 0.05). Conversely, the non-CR group showed no significant changes in ΔT1 (p = 0.738) mapping values but did exhibit changes in ΔT2 and ΔT2* mapping values (p < 0.001).

CONCLUSIONS

The qMRI-derived T1, T2, and T2* mapping demonstrates potential utility in monitoring CI response in LA-NPC, serving as an inherently quantitative tool that warrants further investigation in larger cohorts.