title: Bosniak classification system: a prospective comparison of CT, contrast-enhanced US, and MR for categorizing complex renal cystic masses.
abstract: Background The Bosniak classification was originally based on computed tomographic (CT) findings. Magnetic resonance (MR) and contrast-enhanced ultrasonography (CEUS) imaging may demonstrate findings that are not depicted at CT, and there may not always be a clear correlation between the findings at MR and CEUS imaging and those at CT. Purpose To compare diagnostic accuracy of MR, CEUS, and CT when categorizing complex renal cystic masses according to the Bosniak classification. Material and Methods From February 2011 to June 2012, 46 complex renal cysts were prospectively evaluated by three readers. Each mass was categorized according to the Bosniak classification and CT was chosen as gold standard. Kappa was calculated for diagnostic accuracy and data was compared with pathological results. Results CT images found 27 BII, six BIIF, seven BIII, and six BIV. Forty-three cysts could be characterized by CEUS, 79% were in agreement with CT (κ = 0.86). Five BII lesions were upgraded to BIIF and four lesions were categorized lower with CEUS. Forty-one lesions were examined with MR; 78% were in agreement with CT (κ = 0.91). Three BII lesions were upgraded to BIIF and six lesions were categorized one category lower. Pathologic correlation in six lesions revealed four malignant and two benign lesions. Conclusion CEUS and MR both up- and downgraded renal cysts compared to CT, and until these non-radiation modalities have been refined and adjusted, CT should remain the gold standard of the Bosniak classification.
authors.affiliation: 1 Urological Research Center, Department of Urology, Fredericia Hospital, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Graumann
authors.affiliation: 1 Urological Research Center, Department of Urology, Fredericia Hospital, Denmark.
authors.forename: Susanne Sloth
authors.initials: SS
authors.lastname: Osther
authors.affiliation: 2 Odense University Hospital, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Karstoft
authors.affiliation: 3 Aarhus University Hospital, Skejby, Denmark.
authors.forename: Arne
authors.initials: A
authors.lastname: Hørlyck
authors.affiliation: 1 Urological Research Center, Department of Urology, Fredericia Hospital, Denmark.
authors.forename: Palle Jörn Sloth
authors.initials: PJ
authors.lastname: Osther
mesh_terms: D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000145:classification* / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Kidney neoplasms; computed tomography (CT); contrast enhanced ultrasound (CEUS); magnetic resonance imaging (MRI); renal cystic masses