title: Predictive Value of Chemical-Shift MRI in Distinguishing Clear Cell Renal Cell Carcinoma From Non-Clear Cell Renal Cell Carcinoma and Minimal-Fat Angiomyolipoma.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the diagnostic performance of chemical-shift MRI in the differentiation of clear cell renal cell carcinoma (RCC) from minimal-fat angiomyolipoma (AML) and non-clear cell RCC.
  
  
  METHODS
  In this retrospective study, 97 patients with solid renal tumors without macroscopic fat and with a pathologic diagnosis of clear cell RCC (n = 40), non-clear cell RCC (n = 31), or minimal-fat AML (n = 26) who had undergone renal chemical-shift MRI were included. Size, location, morphology, and signal intensity (SI) of the tumors and the contralateral normal kidneys on T2-weighted and in-phase and opposed-phase images were recorded by readers blinded to the pathology. Percentage tumor-to-renal parenchymal SI drop (percentage SI drop) was calculated and correlated to tumor histology. The statistical analysis was done using Kruskal-Wallis, one-way ANOVA, chi-square, and Fisher exact tests.
  
  
  RESULTS
  The percentage SI drop was significantly higher in clear cell RCC compared with non-clear cell RCC and minimal-fat AML (p < 0.001). Percentage SI drop of greater than 20% had 57.5% sensitivity, 96.5% specificity, and 92% positive predictive value (PPV); and percentage SI drop greater than 29% had 40% sensitivity and 100% specificity for diagnosis of clear cell RCC within the cohort of clear cell RCC, minimal-fat AML, and non-clear cell RCC. A significant proportion of minimal-fat AML (46.2%) displayed homogeneous low T2-weighted SI as opposed to clear cell RCC (5%) and non-clear cell RCC (29%) (p < 0.001).
  
  
  CONCLUSIONS
  The percentage SI drop on chemical-shift MRI had high specificity and moderate sensitivity in predicting clear cell RCC over non-clear cell RCC and minimal-fat AML. A percentage SI drop greater than 20% in a renal mass without macroscopically visible fat has high PPV for clear cell RCC over minimal-fat AML and non-clear cell RCC. Among morphologic features, homogeneous low T2 SI favors minimal-fat AML over RCC.
authors.affiliation: 1 Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, ON, M5G 2M9, Canada.
authors.forename: Kartik S
authors.initials: KS
authors.lastname: Jhaveri
authors.affiliation: 2 Division of Abdominal Imaging and Interventional Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Elmi
authors.affiliation: 1 Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, ON, M5G 2M9, Canada.
authors.forename: Hooman
authors.initials: H
authors.lastname: Hosseini-Nik
authors.affiliation: 2 Division of Abdominal Imaging and Interventional Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Hedgire
authors.affiliation: 3 Department of Pathology, University Health Network, University of Toronto, Toronto, ON, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Evans
authors.affiliation: 4 Department of Surgical Oncology, Division of Urology, University Health Network - Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Jewett
authors.affiliation: 2 Division of Abdominal Imaging and Interventional Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Harisinghani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018207:Angiomyolipoma / Q000175:diagnosis* / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000473:pathology; D002648:Child; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA
keywords: chemical-shift MRI; clear cell renal cell carcinoma; minimal-fat angiomyolipoma; signal intensity drop