title: MR evaluation of sinonasal angiomatous polyp.
abstract: OBJECTIVE
  SAP is a rare lesion of the sinonasal cavity, which may be misdiagnosed as a benign or malignant neoplasm. The purpose of our study was to comprehensively evaluate the MR imaging features of SAP.
  
  
  METHODS
  Forty patients with SAP confirmed pathologically were retrospectively reviewed. Of the 40 patients undergoing MR imaging, 39 had postcontrast T1WI; 30, DCE MR imaging; and 17, DWI. The image features assessed included the location, shape, margin, size, signal intensity, and enhancement pattern on DCE MR imaging and ADC maps.
  
  
  RESULTS
  All 40 SAPs originated from the maxillary sinus, but the lesions frequently extended into the ipsilateral nasal cavity (38/40), toward the choana (19/40), and into the nasopharynx (8/40). The lesions demonstrated hypointensity on T1WI and heterogenous hyperintensity on T2WI. All 40 lesions showed a peripheral hypointense rim on T2WI. Postcontrast MR imaging revealed marked heterogeneous nodular and patchy enhancement. Progressive enhancement was found on DCE MR imaging in 30 cases. The TIC showed a steady enhancement pattern in 3 cases, a rapidly enhancing and slow washout pattern in 6 cases, and a rapidly enhancing and rapid washout pattern in 21 cases. On DWI, the mean ADC value was (1.40 ± 0.20) × 10(-3) mm(2)/s.
  
  
  CONCLUSIONS
  Distinctive features of SAP on conventional MR imaging include internal heterogeneous hyperintensity and a peripheral hypointense rim on T2WI, as well as strong nodular and patchy enhancement on postcontrast MR images. The progressive enhancement on DCE MR imaging can also suggest the diagnosis.
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing. China. yzwang1981@yahoo.com.cn
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Wang
authors.forename: B T
authors.initials: BT
authors.lastname: Yang
authors.forename: Z C
authors.initials: ZC
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Song
authors.forename: J F
authors.initials: JF
authors.lastname: Xian
mesh_terms: D018256:Adenomatous Polyps / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008444:Maxillary Sinus Neoplasms; D008875:Middle Aged; D009296:Nasal Cavity / Q000473:pathology*; D009669:Nose Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult