title: Papillary renal cell carcinoma and clear cell renal cell carcinoma: Differentiation of distinct histological types with contrast - enhanced ultrasonography.
abstract: OBJECTIVE
  Papillary renal cell carcinoma (pRCC) and clear cell renal cell carcinoma (ccRCC) have different biological behaviours and imaging features. The role of contrast-enhanced ultrasound (CEUS) in differentiating these two carcinoma subtypes has not been comprehensively studied.
  
  
  METHODS
  Forty-eight patients with 49 pRCC lesions and 153 patients with 156 ccRCC lesions underwent preoperative conventional ultrasound (US) and CEUS. Among them, 91 patients (25 pRCCs and 66 ccRCCs) also underwent preoperative contrast-enhanced computed tomography (CECT) in our hospital. The characteristics of CEUS and CECT images for each patient imaged were analysed by each of two blinded observers.
  
  
  RESULTS
  Images for five (5/25, 20%) pRCC patients demonstrated equivocal or no enhancement using CECT, while all lesions were enhanced using CEUS. From CEUS, images of pRCCs, when compared with ccRCC images, demonstrated significantly higher frequencies of slow wash-in (59.2% vs. 5.8%), fast wash-out (87.7% vs. 46.1%), and hypo-enhancement (57.1% vs. 7.1%) patterns, p<0.001, as well as the presence of pseudocapsule (42.9% vs. 23.1%), p=0.007. For lesions with large diameters (> 3 cm), a higher percentage of pRCC images demonstrated homogeneous enhancement compared with ccRCC images. Using the combination of slow wash-in, fast wash-out, and hypoenhancement patterns at peak as criteria to differentiate pRCC from ccRCC, positive and negative predictive value, and sensitivity and specificity were found to be 86.7%, 86.9%, 53.1%, and 97.4%, respectively.
  
  
  CONCLUSIONS
  CEUS imaging features of slow-in, fast-out, and hypo-enhancement patterns may be useful for differentiating pRCC and ccRCC. In addition, CEUS may be helpful for diagnosing hypovascular renal lesions that demonstrate equivocal or no enhancement by CECT and, thus, for improving diagnostic confidence.
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China.
authors.forename: Li-Yun
authors.initials: LY
authors.lastname: Xue
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lu
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China. Electronic address: huang.beijian@zs-hospital.sh.cn.
authors.forename: Bei-Jian
authors.initials: BJ
authors.lastname: Huang
authors.affiliation: Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China.
authors.forename: Cui-Xian
authors.initials: CX
authors.lastname: Li
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China.
authors.forename: Jie-Xian
authors.initials: JX
authors.lastname: Wen
authors.affiliation: Department of Ultrasound Zhongshan Hospital, Fudan University, Shanghai institute of medical imaging, Bldg. 1#, 180 Fenglin Rd., Xuhui District, Shanghai 200032, China.
authors.forename: Wen-Ping
authors.initials: WP
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary; D003287:Contrast Media / Q000008:administration & dosage*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007472:Iohexol / Q000008:administration & dosage; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D007682:Kidney Pelvis / Q000000981:diagnostic imaging; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010743:Phospholipids / Q000008:administration & dosage; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013459:Sulfur Hexafluoride / Q000008:administration & dosage; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D007472:Iohexol; D013459:Sulfur Hexafluoride
keywords: Clear cell renal cell carcinoma (ccRCC); Contrast-enhanced computed tomography (CECT); Contrast-enhanced ultrasound (CEUS); Papillary renal cell carcinoma (pRCC); Renal lesions