title: Arterial spin-labeling MR imaging of renal masses: correlation with histopathologic findings.
abstract: OBJECTIVE
  To assess the value of arterial spin-labeling (ASL) perfusion magnetic resonance (MR) imaging in the characterization of solid renal masses by using histopathologic findings as the standard of reference.
  
  
  METHODS
  This prospective study was compliant with HIPAA and approved by the institutional review board. Informed consent was obtained from all patients before imaging. Forty-two consecutive patients suspected of having renal masses underwent ASL MR imaging before their routine 1.5-T clinical MR examination. Mean and peak tumor perfusion levels were obtained by one radiologist, who was blinded to the final histologic diagnosis, by using region of interest analysis. Perfusion values were correlated with histopathologic findings by using analysis of variance. A linear correlation model was used to evaluate the relationship between tumor size and perfusion in clear cell renal cell carcinoma (RCC). P < .05 was considered indicative of a statistically significant difference.
  
  
  RESULTS
  Histopathologic findings were available in 34 patients (28 men, six women; mean age ± standard deviation, 60.4 years ± 11.7). The mean perfusion of papillary RCC (27.0 mL/min/100 g ± 15.1) was lower than that of clear cell RCC (171.6 mL/min/100 g ± 61.2, P = .001), chromophobe RCC (152.9 mL/min/100 g ± 80.7, P = .04), unclassified RCC (208.0 mL/min/100 g ± 41.1, P = .001), and oncocytoma (373.9 mL/min/100 g ± 99.2, P < .001). The mean and peak perfusion levels of oncocytoma (373.9 mL/min/100 g ± 99.2 and 512.3 mL/min/100 g ± 146.0, respectively) were higher than those of papillary RCC (27.0 mL/min/100 g ± 15.1 and 78.2 mL/min/100 g ± 39.7, P < .001 for both), chromophobe RCC (152.9 mL/min/100 g ± 80.7 and 260.9 mL/min/100 g ± 61.9; P < .001 and P = .02, respectively), and unclassified RCC (208.0 mL/min/100 g ± 41.1 and 273.3 mL/min/100 g ± 83.4; P = .01 and P = .03, respectively). The mean tumor perfusion of oncocytoma was higher than that of clear cell RCC (P < .001).
  
  
  CONCLUSIONS
  ASL MR imaging enables distinction among different histopathologic diagnoses in renal masses on the basis of their perfusion level. Oncocytomas demonstrate higher perfusion levels than RCCs, and papillary RCCs exhibit lower perfusion levels than other RCC subtypes.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University of Dusseldorf, Medical Faculty, Dusseldorf, Germany. samuel.brady@stjude.org
authors.forename: Rotem S
authors.initials: RS
authors.lastname: Lanzman
authors.forename: Phil M
authors.initials: PM
authors.lastname: Robson
authors.forename: Maryellen R
authors.initials: MR
authors.lastname: Sun
authors.forename: Amish D
authors.initials: AD
authors.lastname: Patel
authors.forename: Kimiknu
authors.initials: K
authors.lastname: Mentore
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Wagner
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Genega
authors.forename: Neil M
authors.initials: NM
authors.lastname: Rofsky
authors.forename: David C
authors.initials: DC
authors.lastname: Alsop
authors.forename: Ivan
authors.initials: I
authors.lastname: Pedrosa
mesh_terms: D018249:Adenoma, Oxyphilic / Q000175:diagnosis* / Q000473:pathology; D000704:Analysis of Variance; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013113:Spin Labels
chemical_list: D013113:Spin Labels