title: Angiomyolipoma with minimal fat: differentiation of morphological and enhancement features from renal cell carcinoma at CT imaging.
abstract: BACKGROUND
  Angiomyolipoma (AML) with minimal fat may mimic renal cell carcinoma (RCC) and is difficult to distinguish from RCC with imaging studies alone. Precise diagnostic strategies have been explored to discern AML with minimal fat from RCC.
  
  
  OBJECTIVE
  To compare the morphological and enhancement features of AML with minimal fat with those of size-matched RCC on computed tomography (CT).
  
  
  METHODS
  Our study included 143 pathologically proved renal tumors (29 AML with minimal fat: mean diameter, 2.5 cm; range, 1.2-4 cm; 114 RCC: mean diameter, 2.8 cm; range, 1.3-4 cm). All patients underwent biphasic helical CTs. Two radiologists retrospectively evaluated the morphological (i.e. non-round and round appearances, with or without capsule) and enhancement features (i.e., wash-out, gradual, or prolonged). For the parameters that had statistically significance between the two groups, we calculated the positive and negative predictive values by using the univariate χ(2) test. P < 0.05 indicated a significant difference.
  
  
  RESULTS
  AML with minimal fat showed a non-round appearance without a capsule (n = 24, 83%) and prolonged enhancement (n = 20, 69%). The positive and negative predictive values of the non-round appearance without capsule for differentiating AML with minimal fat from RCC were 82.8% and 95.6%, respectively. The positive and negative predictive values of prolonged enhancement were 62.5% and 90.8%, respectively. These features were valuable predictors for AML with minimal fat from RCC.
  
  
  CONCLUSIONS
  CT images with non-round shape without capsule and prolonged enhancements may be used to differentiate AML with minimal fat from RCC.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and SNU-SMG Boramae Medical Center, Seoul, Republic of Korea.
authors.forename: Chang Kyu
authors.initials: CK
authors.lastname: Sung
authors.affiliation: Department of Radiology, Keimyung University College of Medicine, Daegu, Republic of Korea.
authors.forename: See Hyung
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Sungmin
authors.initials: S
authors.lastname: Woo
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and SNU-SMG Boramae Medical Center, Seoul, Republic of Korea.
authors.forename: Min Hoan
authors.initials: MH
authors.lastname: Moon
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Republic of Korea Institute of Radiation Medicine and Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
authors.forename: Sang Youn
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Republic of Korea Institute of Radiation Medicine and Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
authors.forename: Seung Hyup
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Republic of Korea Institute of Radiation Medicine and Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea radjycho@snu.ac.kr.
authors.forename: Jeong Yeon
authors.initials: JY
authors.lastname: Cho
mesh_terms: D000328:Adult; D018207:Angiomyolipoma / Q000000981:diagnostic imaging* / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Angiomyolipoma (AML); computed tomography (CT); renal cell carcinoma (RCC)