title: Diffusion-weighted intravoxel incoherent motion imaging of renal tumors with histopathologic correlation.
abstract: OBJECTIVE
  The aim of this study was to use intravoxel incoherent motion diffusion-weighted imaging to discriminate subtypes of renal neoplasms and to assess agreement between intravoxel incoherent motion (perfusion fraction, fp) and dynamic contrast-enhanced magnetic resonance imaging (MRI) metrics of tumor vascularity.
  
  
  METHODS
  In this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved prospective study, 26 patients were imaged at 1.5-T MRI using dynamic contrast-enhanced MRI with high temporal resolution and diffusion-weighted imaging using 8 b values (range, 0-800 s/mm). Perfusion fraction (fp), tissue diffusivity (Dt), and pseudodiffusivity (Dp) were calculated using biexponential fitting of the diffusion data. Apparent diffusion coefficient (ADC) was calculated with monoexponential fit using 3 b values of 0, 400, and 800 s/mm. Dynamic contrast-enhanced data were processed with a semiquantitative method to generate model-free parameter cumulative initial area under the curve of gadolinium concentration at 60 seconds (CIAUC60). Perfusion fraction, Dt, Dp, ADC, and CIAUC60 were compared between different subtypes of renal lesions. Perfusion fraction was correlated with CIAUC60.
  
  
  RESULTS
  We examined 14 clear cell, 4 papillary, 5 chromophobe, and 3 cystic renal cell carcinomas (RCCs). Although fp had higher accuracy (area under the curve, 0.74) for a diagnosis of clear cell RCC compared with Dt or ADC, the combination of fp and Dt had the highest accuracy (area under the curve, 0.78). The combination of fp and Dt diagnosed papillary RCC and cystic RCC with 100% accuracy, and clear cell RCC and chromophobe RCC, with 86.5% accuracy. There was significant strong correlation between fp and CIAUC60 (r = 0.82; P < 0.001).
  
  
  CONCLUSIONS
  Intravoxel incoherent motion parameters fp and Dt can discriminate renal tumor subtypes. Perfusion fraction demonstrates good correlation with CIAUC60 and can assess degree of tumor vascularity without the use of exogenous contrast agent.
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, NY10016, USA. hersh.chandarana@nyumc.org
authors.forename: Hersh
authors.initials: H
authors.lastname: Chandarana
authors.forename: Stella K
authors.initials: SK
authors.lastname: Kang
authors.forename: Samson
authors.initials: S
authors.lastname: Wong
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Zhang
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arizono
authors.forename: William C
authors.initials: WC
authors.lastname: Huang
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melamed
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Edgar F
authors.initials: EF
authors.lastname: Suan
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
authors.forename: Eric E
authors.initials: EE
authors.lastname: Sigmund
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies