title: Subtype differentiation of renal cell carcinoma using diffusion-weighted and blood oxygenation level-dependent MRI.
abstract: OBJECTIVE
  The purpose of this article is to evaluate the utility of diffusion-weighted imaging (DWI) and blood oxygenation level-dependent (BOLD) MRI for characterizing renal cell carcinoma (RCC) subtypes at 3 T.
  
  
  METHODS
  Seventy-seven patients underwent 3-T DWI and BOLD MRI. Apparent diffusion coefficient (ADC; × 10(-3) mm(2)/s) and rate of spin dephasing (R2*, which equals 1 / T2* relaxation time, or 1/s) values were measured in the three RCC subtypes and normal renal parenchyma, and the results were compared. Statistical analyses were performed using analysis of variance, Student t test, and ROC curve analysis.
  
  
  RESULTS
  Clear cell RCCs showed statistically significantly greater ADC values (1.81 × 10(-3) mm(2)/s) than did papillary (1.29 × 10(-3) mm(2)/s) and chromophobe (1.55 × 10(-3) mm(2)/s) RCCs (p < 0.01); however, no statistically significant differences between papillary and chromophobe RCCs were observed (p = 0.26). Chromophobe RCCs showed the greatest mean R2* (33.6 1/s) of the three subtypes (p < 0.01); however, no statistically significant differences between clear cell RCCs and papillary RCCs were seen (p = 0.48). Low-grade clear cell RCCs showed statistically significantly higher ADC value (1.97 × 10(-3) mm(2)/s) than did high-grade clear cell RCCs (1.66 × 10(-3) mm(2)/s; p = 0.021). For differentiating clear cell RCCs from non-clear cell RCCs, the AUCs of ADC and R2* values were 0.756 × 10(-3) mm(2)/s and 0.607 (1/s), respectively (p = 0.047): cutoff values of ADC (1.4 × 10(-3) mm(2)/s) and R2* (26.3 1/s) resulted in sensitivities and specificities of 85% and 73%, and 86% and 47%, respectively.
  
  
  CONCLUSIONS
  For characterizing RCC subtypes, DWI and BOLD MRI at 3 T may be useful, but the current technique of BOLD MRI seems to have a limited diagnostic accuracy.
authors.affiliation: 1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors.forename: Youn Ah
authors.initials: YA
authors.lastname: Choi
authors.forename: Chan Kyo
authors.initials: CK
authors.lastname: Kim
authors.forename: Sung Yoon
authors.initials: SY
authors.lastname: Park
authors.forename: Seong Whi
authors.initials: SW
authors.lastname: Cho
authors.forename: Byung Kwan
authors.initials: BK
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy; D009942:Organometallic Compounds; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol
keywords: MRI; blood oxygenation level–dependent MRI; diffusion-weighted imaging; renal cell carcinoma; renal neoplasms