Figure 2:

Determination of wall and septa thickness by using the Bosniak classification of cystic renal masses, version 2019. Images show example thicknesses of the walls and septa within 30-mm cystic masses (measurements are to scale). A smooth, thin (≤2-mm) wall is a feature of a Bosniak I cyst, a smooth and thin (≤2-mm) wall and septa are features of a Bosniak II cyst, a smooth and minimally thickened (3-mm) wall or septa is a feature of a Bosniak IIF mass, and a thickened (≥4-mm) enhancing wall or septa is a feature of a Bosniak III mass. The wall in the bottom image is 1 mm thick.