Dynamic contrast-enhanced MRI in orbital lymphoproliferative disorders: Effects of region of interest selection methods on time efficiency, measurement reproducibility, and diagnostic ability.

Background: Previous studies indicated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) could serve as a useful biomarker for differentiating malignant from benign orbital lymphoproliferative disorders (OLPDs).

Purpose: To investigate the influence of different region of interest (ROI) selection methods on the measurements of DCE-MRI parameters, and their diagnostic ability in discriminating malignant from benign OLPDs.

Study Type: Retrospective study.

Population: In all, 46 patients with OLPDs (22 benign and 24 malignant).

Field Strength/sequence: 3.T DCE-MRI using a 2D turbo fast low angle shot sequence postcontrast.

Assessment: DCE-MRI data were analyzed using three different ROI selection methods, including whole-tumor ROI (ROI ), single-slice ROI (ROI ) and hot-spot ROI (ROI ). Quantitative parameters (K , K , V ) were calculated based on a modified Tofts model.

Statistical Testing: Analysis of variance test, intraclass correlation coefficient (ICC), Bland-Altman plots, independent t-test, and receiver operating characteristic curve analyses were used for statistical analyses.

Results: The time required for outlining ROI was significantly longer than ROI and ROI (P < 0.001). The measurements of DCE-MRI-derived parameters based on ROI demonstrated lowest ICC, followed by ROI and ROI . Malignant OLPDs showed significantly higher K than benign mimics (P < 0.001), while no significant differences were found on K (ROI , P = 0.535; ROI , P = 0.557; ROI , P = 0.400) and V (ROI , P = 0.071; ROI , P = 0.079; ROI , P = 0.057). K -ROI showed the highest area under curve for differentiating malignant from benign OLPDs, followed by K -ROI , and Kep-ROI ; however, the differences were not significant (ROI vs. ROI , P = 0.407; ROI vs. ROI , P = 0.363; ROI vs. ROI , P = 0.887).

Data Conclusion: ROI selection methods could have an influence on the measurements of DCE-MRI parameters. Taking measurement time, reproducibility, and diagnostic ability into account, we suggest single-slice ROI to be used for differentiating malignant from benign OLPDs in clinical practice.

Level Of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1298-1305.