title: Differentiation of large (≥ 5 cm) gastrointestinal stromal tumors from benign subepithelial tumors in the stomach: radiologists' performance using CT.
abstract: OBJECTIVE
  To identify significant CT findings for the differentiation of large (≥ 5 cm) gastric gastrointestinal stromal tumors (GIST) from benign subepithelial tumors and to assess whether radiologists' performance in differentiation is improved with knowledge of significant CT criteria.
  
  
  METHODS
  One-hundred twenty patients with pathologically proven large (≥ 5 cm) GISTs (n=99), schwannomas (n=16), and leiomyomas (n=5) who underwent CT were enrolled. Two radiologists (A and B) retrospectively reviewed their CT images in consensus for the location, size, degree and pattern of enhancement, contour, growth pattern and the presence of calcification, necrosis, surface ulceration, or enlarged lymph nodes. CT findings considered significant for differentiation were determined using uni- and multivariate statistical analyses. Thereafter, two successive review sessions for the differentiation of GIST from non-GIST were independently performed by two other reviewers (C and D) with different expertise of 2 and 9 years using a 5-point confidence scale. At the first session, reviewers interpreted CT images without knowledge of significant CT findings. At the second session, the results of statistical analyses were provided to the reviewers. To assess improvement in radiologists' performance, a pairwise comparison of receiver operating curves (ROC) was performed.
  
  
  RESULTS
  Heterogeneous enhancement, presence of necrosis, absence of lymph nodes, and mean size of ≥ 6 cm were found to be significant for differentiating GIST from schwannoma (P<0.05). Non-cardial location, heterogeneous enhancement, and presence of necrosis were differential CT features of GIST from leiomyoma (P<0.05). Multivariate analyses indicated that absence of enlarged LNs was the only statistically significant variable for GIST differentiating from schwannoma. The area under the curve of both reviewers obtained using ROC significantly increased from 0.682 and 0.613 to 0.903 and 0.904, respectively, with information of the significant CT findings differentiating GISTs from non-GISTs (P<0.001).
  
  
  CONCLUSIONS
  Non-cardial location, heterogeneous enhancement, presence of necrosis, larger lesion size, and absence of lymphadenopathy are highly suggestive CT findings for large GISTs in differentiation from schwannomas or leiomyomas. Regardless of radiologists' expertise, diagnostic performance in differentiation can be significantly improved with knowledge of these CT findings.
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea.
authors: Ye Ra
authors: YR
authors: Choi
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea; The Institute of Radiation Medicine, Seoul National University Hospital, Republic of Korea. Electronic address: shkim7071@gmail.com.
authors: Se Hyung
authors: SH
authors: Kim
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea.
authors: Sun-Ah
authors: SA
authors: Kim
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea; The Institute of Radiation Medicine, Seoul National University Hospital, Republic of Korea.
authors: Cheong-Il
authors: CI
authors: Shin
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea.
authors: Hyung Jin
authors: HJ
authors: Kim
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea.
authors: Seong Ho
authors: SH
authors: Kim
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea; The Institute of Radiation Medicine, Seoul National University Hospital, Republic of Korea.
authors: Joon Koo
authors: JK
authors: Han
authors: Department of Radiology, Seoul National University Hospital, Republic of Korea; The Institute of Radiation Medicine, Seoul National University Hospital, Republic of Korea.
authors: Byung Ihn
authors: BI
authors: Choi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002983:Clinical Competence; D003937:Diagnosis, Differential; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging*; D006801:Humans; D018230:Leiomyoma, Epithelioid / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Computed tomography; Gatrointestinal stromal tumors; Leiomyoma; Schwannoma; Stomach neoplasms; Subepithelial tumors