Caudate–right lobe ratio

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Caudate-right lobe ratio (C/RL) is used in the assessment of livers, usually in the setting of cirrhosis, in which there is atrophy of the right lobe with hypertrophy of the caudate lobe.

Method for measuring

image: axial slice immediately below the bifurcation of the main portal vein
line 1: a parasagittal line drawn through the right lateral border of the portal vein
line 2: a parasagittal line drawn through the left lateral border of the caudate lobe
line 3: line orthogonal to lines 1 and 2 midway between the portal vein and the IVC extended to the right liver edge
RL measurement: along line 3, from right liver edge to line 1
C measurement: along line 3, between line 1 and line 2
caudate-right lobe ratio: C/RL

Interpretation

C/RL <0.6 = normal (does not exclude cirrhosis)
C/RL 0.6-0.65 = borderline
C/RL >0.65 = 96% likely to be cirrhotic
C/RL >0.73 = 99% likely to be cirrhotic

Modified measurement

An alternative placement of line 1 has been proposed by Awaya et al. as being more sensitive and specific . Rather than line 1 intersecting the right lateral border of the main portal vein, they describe drawing line 1 through the right lateral aspect of the right portal vein bifurcation.