The value of conventional MRI combined with diffusion weighted imaging in the differential diagnosis of orbital lymphoproliferative disorders / 中华放射学杂志

ABSTRACT

Objective To investigate the diagnostic value of conventional MRI combined with DWI in the differential diagnosis of orbital lymphoproliferative disorders (LPD). Methods As a retrospective study, 42 patients were enrolled, including 23 orbital lymphoma and 19 benign orbital LPD confirmed pathologically or clinically. These patients underwent conventional MR, DWI and contrast?enhanced MRI examination of orbit. Qualitative MR imaging features [location, margin, patient ratio of involved quadrants (≥2), signal intensity,“flow void sign”, sinusitis] and quantitative features [ADC and contrast enhanced ratio of the lesion to temporal muscle (CER)] were evaluated. Chi?square test and t test were used for the analysis of qualitative and quantitative features between lymphoma and benign orbital LPD groups, respectively. Multivariate Logistic regression analysis was employed to identify the significant variable for predicting malignant LPD. ROC analysis was used to evaluate the ability of the diagnostic models established based on identified variables. Results “Flow void sign”(9 lymphomas and 17 benign LPDs) and sinusitis (5 lymphomas and 13 benign LPDs) were statistically significant (P0.05). Both ADC [(0.79±0.09)×10?3 mm2/s of lymphoma, (1.29±0.35)×10?3 mm2/s of benign LPD] and CER (1.43±0.17 of lymphoma, 1.79±0.31 of benign LPD) between the two groups had significant difference (t=-6.630, -8.257;P<0.01). Multivariate logistic regression analysis showed that ADC value, CER and“flow void sign”were significant variables for predicting malignant orbital LPD (P<0.05). ROC curve showed that ADC value was the most significant single variable in differentiating orbital LPD [threshold value, 0.74 × 10- 3 mm2/s; areas under ROC curve (AUC), 0.97; sensitivity, 87.0%; specificity, 94.7%]. Combination of ADC and CER could further improve the specificity in differentiating benign from malignant orbital LPD (AUC, 0.90;sensitivity, 78.3%;specificity, 100.0%, accuracy 88.1%). Conclusions ADC, CER and“flow void sign”on T2WI were significant variables for predicting malignant orbital LPD. ADC value was the most significant single variable. Combination of ADC and CER could further improve the specificity in differentiating benign from malignant orbital LPD.