High Resolution Diffusion-Weighted Imaging for Solitary Orbital Tumors: 3D Turbo Field Echo with Diffusion-Sensitized Driven-Equilibrium (DSDE-TFE) Preparation Technique

Purpose: To differentiate cystic from solid solitary intraorbital tumors using 3D turbo field echo with diffusion-sensitized driven-equilibrium preparation without contrast material. Materials and Methods: This retrospective study was approved by our institutional review boards, and written informed consent was waived. A total of 26 patients with intraorbital tumors were studied. Motion probing gradients were conducted at one direction with b‑values of 0 and 500 s/mm². The voxel size was 1.5 × 1.5 × 1.5 mm³, and acquisition time was 5 min 22 s. Additionally, fat-suppressed T2-weighted imaging (T2WI) and T1WI were obtained. The apparent diffusion coefficients (ADC) of the lesions were measured. Signal intensity on conventional magnetic resonance imaging (MRI) compared to normal appearing white matter was also measured. Statistical analysis was performed with Mann-Whitney U-test, the Steel-Dwass test and the receiver operating characteristic (ROC) analysis. Results: There were 10 cystic (7 dermoids, 2 epidermoids, and 1 cystadenoma) and 16 solid (8 cavernous hemangiomas, 6 pleomorphic adenomas, 1 adenocarcinoma, and 1 sebaceous carcinoma) tumors. The ADC of the cystic tumors (mean ± SD; 2.21 ± 0.76 × 10⁻³ mm²/s) was statistically significantly lower than that of solid tumors (1.43 ± 0.41 × 10⁻³ mm²/s; P < 0.05).; however, there were no statistically significant differences on conventional MRI (P > 0.05). There were no statistically significant differences among tumor subtypes in all parameters (P > 0.05). The ROC analysis showed the best diagnostic performance with ADC (Az = 0.77). Conclusion: With its insensitivity to field inhomogeneity and high spatial resolution, the 3D DSDE-TFE technique enabled us to discriminate cystic tumors from solid tumors.