Table 1 Previously reported anatomical variations of the bronchi in the right upper lobe

Normal findings and most common bronchial variations

Trifurcation B¹, B², B³

3DCT;

Bronchography

Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]

Bifurcation B^1 + 2, B³

3DCT; Bronchography

Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]

Bifurcation B^1 + 3, B²

3DCT; Bronchography

Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]

Bifurcation B^2 + 3, B¹

3DCT; Bronchography

Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]

Bifurcation B^1a + 2, B^1b + 3

3DCT; Bronchography

Nagashima et al. (2015) [3]; Zhang et al. (2021) [9]

Bifurcation B^1 + 2a, B^2b + 3

3DCT; Bronchography

Nagashima et al. (2015) [3]; Zhang et al. (2022) [10]

Quadrifurcation

3DCT; Bronchography

Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]

Rare variations

Tracheal bronchus

Thoracoscopy;

Bronchography

Yurugi et al. (2012) [11]; Martín-Ruiz et al. (2021) [4]

Right upper lobe bronchus ectopic to the intermediate bronchus

3DCT

Huang et al. (2020) [5]

B¹ ectopic to the lateral wall of the trachea or

the right main bronchus (Right B¹

Type))

CT

Yaginuma (2020) [7]

B² ectopic to the intermediate bronchus (Right B²

Type)

CT

Yaginuma (2020) [7]

B³ ectopic to the intermediate bronchus (Right B³

Type)

3DCT

Ghaye et al. (2001) [6];

Yaginuma (2020) [7]