title: Lipid in renal clear cell carcinoma: detection on opposed-phase gradient-echo MR images.
abstract: OBJECTIVE
  To determine if comparison of in-phase and opposed-phase gradient-echo magnetic resonance (MR) images enables detection of lipid in renal clear cell carcinoma.
  
  
  METHODS
  A retrospective search of MR and pathologic records identified 43 patients with biopsy-proved renal masses who underwent in-phase and opposed-phase MR imaging. Thirty-three patients had renal cell carcinoma (27 with clear cell carcinoma), and 10 patients had other renal tumors. With MR images, a region-of-interest measurement of signal intensity of the renal mass was divided by that of reference tissue. In each patient, a ratio of these region-of-interest measurements on the opposed-phase images to those on the in-phase images was calculated and termed the opposed-phase/in-phase signal intensity ratio (OIR).
  
  
  RESULTS
  The mean OIR of clear cell carcinomas was significantly different from that of other renal masses (P < .0002); in 16 (59%) of 27 patients with clear cell carcinoma, the OIR was less than 2 standard deviations below the mean OIR of other masses. In cases of clear cell carcinoma, focal signal intensity on opposed-phase images was less than that on in-phase images.
  
  
  CONCLUSIONS
  On opposed-phase images, some clear cell carcinomas show relative focal and diffuse loss of signal intensity. In renal masses, this signal intensity loss-which is consistent with lipid-does not necessarily indicate angiomyolipoma.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA 19107-5244, USA.
authors.forename: E K
authors.initials: EK
authors.lastname: Outwater
authors.forename: M
authors.initials: M
authors.lastname: Bhatia
authors.forename: E S
authors.initials: ES
authors.lastname: Siegelman
authors.forename: M A
authors.initials: MA
authors.lastname: Burke
authors.forename: D G
authors.initials: DG
authors.lastname: Mitchell
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018207:Angiomyolipoma / Q000175:diagnosis; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D008055:Lipids