Table 1 Seven proposed COVID-19 CT severity score systems

CTSS1 [2, 3]

Three zones in each lung are divided by carina and lower pulmonary vein

1–4 according to percentage of involvement (< 25, 25–49, 50–74, > 75)

24

CTSS2 [4]

The same zonal concept as CTSS1 with additional division of each zone into anterior and posterior regions divided by midpoint of diaphragm antero-posteriorly

1–4 according to percentage of involvement (< 25, 25–49, 50–74, > 75)

48

CTSS3 [5, 6]

Five anatomic lobes of the lungs

1–4 according to percentage of involvement (< 25, 25–49, 50–74, > 75)

20

CTSS4 [7, 8]

Five anatomic lobes of the lungs

1–5 according to percentage of involvement (< 5, 5–25, 25–49, 50–74, > 75)

25

CTSS5 [9]

Five anatomic lobes of the lungs

1–4 according to the diameter of the largest lesion in each lobe (< 1 cm, 1-3 cm, > 3 cm up to 50% of the lobe, > 50% of a lobe

20

CTSS6 [10]

18 anatomic segments of the lung with an additional division of apico-posterior segment of the left upper lobe into apical and posterior divisions and anteromedial segment of the left lower lobe into anterior and medial segments

No involvement = 0

 < 50% involvement = 1

 ≥ 50% involvement = 2

40

CTSS7 [current authors]

Five anatomic lobes of the lungs with additional consideration of the lingula as a separate lobe

1–5 according to percentage of involvement (< 5, 5–25, 25–49, 50–74, > 75)

30