title: Differential radiologic characteristics of renal tumours on multiphasic computed tomography.
abstract: BACKGROUND
  This study analysed the tumour attenuation characteristics of different subtypes of renal cell carcinomas (RCCs), including clear cell RCC (ccRCC), papillary RCC (pRCC), mixed RCC, chromophobe RCC (chRCC) and oncocytoma.
  
  
  METHODS
  We randomly selected 100 RCC cases that underwent nephrectomy between 2004 and 2012 from a collaborative database. Of these cases, 36 were excluded due to the absence of available imaging. The remaining 64 cases comprised 35 ccRCCs, 11 pRCCs, eight chRCCs, seven mixed RCCs and three oncocytomas. The cases were classified as computed tomography (CT) kidney, CT urogram (with plain, nephrographic and pyelographic phases) or CT abdomen (with portovenous and delayed phases). A circular region of interest (ROI) ≥ 1 cm2was drawn and the same standard ROI size was used for each phase at the same site; three different circular ROIs were drawn per lesion per phase. Analysis of variance and t-test were used to examine differences in the radiological characteristics.
  
  
  RESULTS
  There was no statistical difference in the attenuation and degree of enhancement between mixed RCCs and ccRCCs. The attenuation and degree of enhancement of the oncocytomas were significantly higher than those of the other RCC subtypes.
  
  
  CONCLUSIONS
  While mixed RCCs did not have attenuation characteristics that differed significantly from those of ccRCCs, oncocytomas can be distinguished from ccRCCs, pRCCs, chRCCs and mixed RCCs by their high radiological density and enhancement. The ability to differentiate oncocytomas from these tumours potentially allows the preoperative selection of patients with small renal masses for conservative management.
authors.affiliation: Department of Diagnostic Radiology, Singapore General Hospital, Singapore.
authors.forename: Boon Chye
authors.initials: BC
authors.lastname: Ching
authors.affiliation: Division of Medical Oncology, National Cancer Centre Singapore, Singapore.
authors.forename: Hui Shan
authors.initials: HS
authors.lastname: Tan
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: Puay Hoon
authors.initials: PH
authors.lastname: Tan
authors.affiliation: Division of Medical Oncology, National Cancer Centre Singapore, Singapore.
authors.forename: Chee Keong
authors.initials: CK
authors.lastname: Toh
authors.affiliation: Division of Medical Oncology, National Cancer Centre Singapore, Singapore.
authors.forename: Ravindran
authors.initials: R
authors.lastname: Kanesvaran
authors.affiliation: Division of Medical Oncology, National Cancer Centre Singapore, Singapore.
authors.forename: Quan Sing
authors.initials: QS
authors.lastname: Ng
authors.affiliation: Division of Medical Oncology, National Cancer Centre Singapore, Singapore.
authors.forename: Min Han
authors.initials: MH
authors.lastname: Tan
mesh_terms: D018249:Adenoma, Oxyphilic / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000453:epidemiology; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012846:Singapore / Q000453:epidemiology
keywords: attenuation; clear cell renal cell carcinoma; enhancement; radiodensity; renal cell carcinoma