Synopsis

This work assessed the feasibility of quantitative parameters derived from dynamic contrast enhanced MR imaging (DCE-MRI) and evaluated the value of quantitative dynamic contrast enhanced MR imaging in the differential diagnosis between lymphoma and inflammatory pseudotumor in the orbit.

From the results we can see that it is feasible that quantitative parameters of DCE-MRI can be applied in the differential diagnosis between lymphoma and inflammatory pseudotumor in the orbit. Thus, it can probably be used as imaging biomarkers to predict prognosis and aggressiveness of orbital lymphoma.

Purpose

To assess the feasibility of quantitative parameters derived from dynamic contrast enhanced MR imaging (DCE-MRI) and evaluate the value of quantitative dynamic contrast enhanced MR imaging in the differential diagnosis between lymphoma and inflammatory pseudotumor in the orbit.

Materials and Methods

83 patients with orbital masses (39 orbital lymphomas and 44 orbital inflammatory pseudotumors) confirmed by pathology were enrolled in the study ^[1,2]. Two methods of selecting regions of interest (ROI) were compared to obtain quantitative parameters: (a) a round or ovoid region of 8mm² covering the earliest and most enhanced area, and (b) covering the lesion excluding the hemorrhage and necrosis on the largest slice (Figure 1) ^[3-4]. Parametric maps were obtained for quantitative parameters including K^trans, V_e and K_ep (Figure 2) ^[5]. Quantitative parameters that distinguish orbital lymphoma from orbital inflammatory pseudotumor were analyzed by using independent rank sum test, independent T-test, receiver operating characteristic curves (ROC) and Z test. P value of less than 0.05 was considered to represent a significant difference.

Results

K_ep values were significantly higher in orbital lymphoma than in orbital inflammatory pseudotumor. In contrast, V_e values were significantly lower in orbital lymphoma than in orbital inflammatory pseudotumor (p<0.05). However, K^trans showed no difference between orbital lymphoma and orbital inflammatory pseudotumor (p>0.05) (Table 1). Two methods of selecting ROI showed no difference in distinguishing lymphoma from inflammatory pseudotumor of orbit (p>0.05). K_ep (method a of selecting ROI) distinguished lymphoma from inflammatory pseudotumor in the orbit with sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 97.4%, 52.3%, 77.5%, 95.8%, 73.5% respectively. V_e (method a of selecting ROI) distinguished lymphoma from inflammatory pseudotumor in the orbit with sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 54.5%, 79.5%, 70%, 66%, 67.5% respectively. V_e (method b of selecting ROI) distinguished lymphoma from inflammatory pseudotumor in the orbit with sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 48.7%, 86.4%, 76%, 65.5%, 68.7% respectively (Table 2).

Conclusions

It is feasible that quantitative parameters of DCE-MRI can be applied in the differential diagnosis between lymphoma and inflammatory pseudotumor in the orbit. Thus, it can probably be used as imaging biomarkers to predict prognosis and aggressiveness of orbital lymphoma.

Acknowledgements

We would like to thank the support of National Natural Science Foundation of China(81571649) , Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX201704) , High Level Health Technical Personnel of Bureau of Heath in Beijing(2014-2-005) and “Key Talent Project”of Beijing (2014001).