title: Primary ovarian endometrioid adenocarcinoma: magnetic resonance imaging findings including a preliminary observation on diffusion-weighted imaging.
abstract: OBJECTIVE
  This study aimed to investigate the magnetic resonance imaging (MRI) features of ovarian endometrioid adenocarcinoma (OEC) and to evaluate conventional MRI and diffusion-weighted imaging (DWI) for diagnosing OEC.
  
  
  METHODS
  Twenty patients with OEC proven by surgery and pathology underwent MRI. The MRI features of the tumors evaluated included laterality, shape, size, configuration, mural nodules, signal intensity, apparent diffusion coefficient (ADC) values, enhancement, peritoneal implants, ascites, and synchronous primary cancer (SPC) of the ovary and endometrium.
  
  
  RESULTS
  Unilateral ovarian masses were observed in 18 (90%) of the 20 patients with 22 OEC lesions, whereas the remaining 2 (10%) patients had bilateral masses. Oval, lobulated, and irregular shapes were observed in 13 (59%), 6 (27%), and 3 (14%) tumors, respectively. The maximum diameter of the tumors ranged from 3.7 to 22.5 cm, with a mean of 11.2 ± 5.1 cm. Fifteen (68%) masses were mainly cystic with mural nodules, 5 (23%) were mixed cystic-solid, and 2 (9%) were solid. The solid components of tumors showed isointensity (100%) on T1-weighted imaging (T1WI), heterogeneous hyperintensity on T2-weighted imaging (T2WI) (86%), and hyperintensity on DWI (82%), with a mean ADC value of (0.96 ± 0.20) × 10 mm/s. The cystic components showed isointensity or hyperintensity (85%) on T1WI, hyperintensity on T2WI (100%), and hypointensity on DWI (63%), with a mean ADC value of (2.27 ± 0.27) × 10 mm/s. Ten (50%) of the patients were SPC. The mean ADC values of the solid components were (0.85 ± 0.19) × 10 mm/s and (1.08 ± 0.15) × 10 mm/s in only-OEC and SPC, respectively, with a statistically significant difference (P = 0.012).
  
  
  CONCLUSIONS
  Ovarian endometrioid adenocarcinoma usually appears as a large, oval, or lobulated cystic mass with mural nodules. Cystic components show isointensity or hyperintensity on T1WI, solid components and hyperintensity on T2WI and DWI. Synchronous primary cancer of the ovary endometrium is another characteristic feature of OEC.
authors.affiliation: From the *Department of Radiology, Jinshan Hospital and Shanghai School of Medicine, Fudan University, Shanghai; †Department of Radiology, Nantong Cancer Hospital, Nantong, Jiangsu; and ‡Department of Radiology, Xinhua Hospital and Shanghai School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Hai Ming
authors.initials: HM
authors.lastname: Li
authors.forename: Jin Wei
authors.initials: JW
authors.lastname: Qiang
authors.forename: Gan Lin
authors.initials: GL
authors.lastname: Xia
authors.forename: Shu Hui
authors.initials: SH
authors.lastname: Zhao
authors.forename: Feng Hua
authors.initials: FH
authors.lastname: Ma
authors.forename: Song Qi
authors.initials: SQ
authors.lastname: Cai
authors.forename: Feng
authors.initials: F
authors.lastname: Feng
authors.forename: Ai Yan
authors.initials: AY
authors.lastname: Fu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018269:Carcinoma, Endometrioid / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity