Comparison of Bosniak Classification of cystic renal masses version 2019 assessed by CT and MRI

Jason Chan; Jin Hui Yan; Javeria Munir; Heba Osman; Sumaya Alrasheed; Trevor McGrath; Trevor Flood; Nicola Schieda

doi:10.1007/s00261-021-03236-z

Comparison of Bosniak Classification of cystic renal masses version 2019 assessed by CT and MRI

Abdom Radiol (NY). 2021 Nov;46(11):5268-5276. doi: 10.1007/s00261-021-03236-z. Epub 2021 Aug 14.

Authors

Jason Chan^#¹, Jin Hui Yan^#¹, Javeria Munir¹, Heba Osman¹, Sumaya Alrasheed¹, Trevor McGrath¹, Trevor Flood², Nicola Schieda³

Affiliations

¹ Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, 1053 Carling Avenue, C1, Ottawa, ON, K1Y 4E9, Canada.
² Department of Anatomical Pathology, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada.
³ Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, 1053 Carling Avenue, C1, Ottawa, ON, K1Y 4E9, Canada. nschieda@toh.ca.

^# Contributed equally.

PMID: 34390368
DOI: 10.1007/s00261-021-03236-z

Abstract

Objective: To compare imaging features in cystic masses imaged with both CT and MRI using Bosniak Classification version 2019 (Bosniak.v2019) and original Bosniak Classification (Bosniak.original).

Materials and methods: This IRB-approved, retrospective, cross-sectional study evaluated sixty-five consecutively identified cystic (≤ 25% enhancing) masses imaged by CT and MRI between 2009 and 2019: 35 with histologic diagnosis and 30 Bosniak.v2019 Class 2 and Class 2F cystic masses verified by an expert radiologist (R1) with minimum 5-year stability. Three radiologists (R2, R3, R4) independently evaluated CT, followed by MRI and assigned Bosniak.original and Bosniak.v2019 class in two sessions separated by ≥ 1 month and assessed the following: septa number, septa/wall thickness, and protrusions. Discrepancies were resolved by consensus with R1.

Results: There was 70.8% agreement (kappa = 0.60, p = 0.0146) in class assigned by CT versus MRI for Bosniak.original and 72.3% agreement (kappa = 0.63, p = 0.006) for Bosniak.v2019. Increased septa number (p < 0.001) and more protrusions (p = 0.034) were identified on MRI, with no differences in septal/wall thickness (p = 0.067, 0.855) or protrusion size (p = 0.467). For both CT and MRI, Bosniak.v2019 improved specificity (79.0% [95% confidence interval 71.0-87.0%] CT, 70% [62.0-77.0%] MRI) compared to Bosniak.original (63.0% [56.0-69.0%] CT, 66.0% [58.0-74.0%] MRI) with maintained sensitivity and higher overall accuracy. Inter-observer agreement was similar-to-slightly higher for Bosniak.v2019 (K = 0.44 CT, 0.39 MRI) versus Bosniak.original (K = 0.35 CT, 0.37 MRI).

Conclusion: Class assignment differs in cystic masses evaluated by CT versus MRI for original and v2019 Bosniak Classification with similar-to-slightly higher agreement and improved specificity and higher overall accuracy on both CT and MRI with Bosniak version 2019.

Keywords: Bosniak; Computed tomography; Cystic masses; Kidney; Magnetic resonance imaging; Renal.

MeSH terms

Cross-Sectional Studies
Humans
Kidney Diseases, Cystic* / diagnostic imaging
Kidney Neoplasms*
Magnetic Resonance Imaging
Retrospective Studies
Tomography, X-Ray Computed