Evaluation of multiparametric MRI differentiating sinonasal angiomatous polyp from malignant tumors

Sinonasal angiomatous polyps (SAPs) can be misdiagnosed as malignant tumors due to aggressive clinical behaviors. The purpose of this study was to evaluate the diagnostic accuracy of multiparametric MRI in differentiating SAPs from malignant tumors.

This retrospective study included 31 patients with pathologically proven SAPs and 36 patients with malignant tumors in maxillary sinus and nasal cavity. All the patients underwent conventional MRI and dynamic contrast-enhanced (DCE) MRI on 3T MR scanners. Diffusion-weighted (DW) MR imaging was performed in 45 patients. All the MR images were retrospectively analyzed independently by two authors.

Significant differences were found in T1 homogeneity, T2 signal intensity ratio, peripheral hypointense rim on T2WI, and soft tissue infiltration between SAP and malignant tumors (P = 0.004, < 0.001, < 0.001, and = 0.001, respectively). SAPs usually show heterogeneous signal intensity on T1WI, peripheral hypointense rim on T2WI, and higher T2 signal intensity ratio. The tumor size of SAP (4.01 ± 1.08 cm) was slightly smaller than that of malignant tumors (4.56 ± 1.12 cm) (P = 0.045). There were significant differences in DCE-MRI parameters including Tpeak, CImax, WR, TIC types, and progressive enhancement (P = 0.009, < 0.001, = 0.001, = 0.001, and < 0.001, respectively) between SAPs and malignant tumors. All the 31 SAPs showed progressive enhancement on DCE-MRI, while none of the malignant tumors showed progressive enhancement (accuracy 100%). The mean ADC of SAP (1.75 ± 0.30 × 10^-3 mm²/s) was higher than that of malignant tumors (1.18 ± 0.31 × 10^-3 mm²/s) (P < 0.001).

Multiparametric MRI showed high diagnostic performance in differentiating SAPs from malignant tumors. Progressive enhancement on DCE-MRI is the most effective feature of SAP.