Cystic renal mass — CT / MRI (Bosniak)

CTMRIBosniak version 2019

Characterization of a cystic renal mass on contrast-enhanced CT or MRI.

Applies to

Cystic renal mass on dedicated contrast-enhanced CT or MRI

Does not apply to

Non-contrast studies that cannot assess enhancement
Suspected infection or infarction rather than a cystic neoplasm
Patients under 18 years

What to report

Tap an item to check it off while dictating.

1.Size and laterality
Maximum diameter and side; segmental location for surgical planning.
2.Attenuation / signal
Unenhanced and enhanced HU (CT) or T1/T2 signal (MRI). Simple fluid is −9 to 20 HU.
3.Wall
Thickness and regularity. Thin and smooth is ≤2 mm; describe any thickening or irregularity.
4.Septa
Number and thickness; whether smooth or irregular, and whether enhancing.
5.Enhancement
An increase of ≥20 HU (CT) is unequivocal enhancement. Report enhancing nodules explicitly.
Pitfall: Pseudo-enhancement of small hyperdense cysts can mimic true enhancement — compare ROIs carefully.
6.Calcification
None/thin versus thick or nodular.
7.Comparison
Compare with priors for interval change in size or complexity.

Sources

Bosniak Classification version 2019 — Silverman SG et al. Radiology (2019)

Content review: Content pending clinical review · 2026-07-09

Educational reference for trained clinicians. Verify every result against the cited original guideline before use. Not a substitute for clinical judgment or medical advice.

Cystic renal mass — CT / MRI (Bosniak)

What to report

Scores & calculators

Bosniak classification

Ellipsoid volume

Sources