Equilibrium phase images of the liver using a contrast-enhancement boost instead of the portal vein phase

Table 1 The patients’ baseline characteristics

Characteristics	mean ± SD
Males:Females	37:16
Age (years)	71.63 ± 11.99
Body height (cm)	160.57 ± 9.55
Body weight (kg)	60.65 ± 10.5
BMI (kg/m2)	23.45 ± 3.21
CTDIvol (mGy)	17.38 ± 4.42
SSDE (mGy)	23.92 ± 4.79

BMI: Body mass index; CTDI_vol: Volume computed tomography dose inde; SSDE: Size-specific dose estimates.

Table 2 Comparison of the quantitative image analysis of blood vessels and hepatic parenchyma, mean ± SD

Characteristics	PVP	EP	CE-boost (EP)	aP value	bP value
CT value (HU)
Main portal vein	185.48 ± 25.51	135.97 ± 18.00	182.53 ± 27.00	0.50	< 0.01
Right portal vein	183.65 ± 24.06	133.65 ± 16.45	179.18 ± 22.47	0.36	< 0.01
Left portal vein	186.21 ± 24.54	134.74 ± 16.69	181.32 ± 23.89	0.36	< 0.01
Segmental branch of the portal vein	177.23 ± 20.31	132.20 ± 15.70	171.61 ± 19.99	0.17	< 0.01
Inferior vena cava	137.11 ± 23.09	122.85 ± 16.61	164.10 ± 24.40	< 0.01	< 0.01
Hepatic parenchyma	120.25 ± 15.67	100.60 ± 12.93	120.36 ± 16.54	0.96	< 0.01
Image noise	18.04 ± 3.33	17.68 ± 3.62	14.15 ± 5.21	< 0.01	< 0.01
Contrast-to-noise ratio
Main portal vein	3.72 ± 1.44	2.08 ± 1.09	4.94 ± 2.66	< 0.01	< 0.01
Right portal vein	3.61 ± 1.40	1.95 ± 1.00	4.69 ± 2.42	< 0.01	< 0.01
Left portal vein	3.77± 1.40	2.04 ± 1.05	4.94 ± 2.70	0.02	< 0.01
Segmental branch of the portal vein	3.26 ± 1.15	1.85 ± 0.83	4.08 ± 1.94	0.03	< 0.01
Inferior vena cava	0.95 ± 1.63	1.30 ± 0.95	3.49 ± 2.30	< 0.01	< 0.01
Hepatic parenchyma	3.07 ± 1.09	1.90 ± 0.83	3.34 ± 1.74	0.62	< 0.01
Signal-to-noise ratio
Main portal vein	10.61 ± 2.30	7.97 ± 1.90	14.48 ± 5.42	< 0.01	< 0.01
Right portal vein	10.50 ± 2.21	7.85 ± 1.84	14.23 ± 5.21	< 0.01	< 0.01
Left portal vein	10.66 ± 2.31	7.94 ± 1.97	14.48 ± 5.53	< 0.01	< 0.01
Segmental branch of the portal vein	10.15 ± 2.13	7.75 ± 1.74	13.62 ± 4.80	< 0.01	< 0.01
Inferior vena cava	7.84 ± 1.98	7.20 ± 1.70	13.03 ± 4.97	< 0.01	< 0.01
Hepatic parenchyma	6.89 ± 1.55	5.90 ± 1.35	9.54 ± 3.44	< 0.01	< 0.01
Figure of merit
Main portal vein	0.94 ± 0.75	0.33 ± 0.49	1.97 ± 2.83	0.01	< 0.01
Right portal vein	0.89 ± 0.75	0.28 ± 0.37	1.72 ± 2.40	< 0.01	< 0.01
Left portal vein	0.98 ± 0.79	0.32 ± 0.40	1.99 ± 2.84	< 0.01	< 0.01
Segmental branch of the portal vein	0.71 ± 0.51	0.24 ± 0.24	1.24 ± 1.32	< 0.01	< 0.01
Inferior vena cava	0.20 ± 0.47	0.15 ± 0.25	1.08 ± 1.87	< 0.01	< 0.01
Hepatic parenchyma	0.68 ± 0.50	0.28 ± 0.23	0.96 ± 1.03	0.67	< 0.01

^aP value of the portal vein phase vs contrast enhancement boost of the equilibrium phase.

^bP value of the equilibrium phase vs ontrast enhancement boost of the equilibrium phase.

PVP: Portal vein phase; EP: Equilibrium phase; CE-boost (EP): Contrast enhancement boost of the equilibrium phase; HU: Hounsfield units.

Table 3 Comparison by qualitative image analysis, mean ± SD

Characteristics	PVP	EP	CE-boost (EP)	aP value	bP value
Vascular visualization
Portal vein	4 ± 0.00	3.97 ± 0.15	4 ± 0.00	NA	0.16
Segmental branch of the portal vein	3.97 ± 0.15	3.12 ± 0.55	3.88 ± 0.42	0.14	< 0.01
Lesion conspicuity	3.29 ± 0.60	3.21 ± 0.69	3.63 ± 0.51	< 0.01	< 0.01
Image noise	3.85 ± 0.34	3.85 ± 0.34	3.14 ± 0.44	< 0.01	< 0.01

^aP value of the portal vein phase vs contrast enhancement boost of the equilibrium phase.

^bP value of the equilibrium phase vs contrast enhancement boost of the equilibrium phase.

PVP: Portal vein phase; EP: Equilibrium phase; CE-boost (EP): Contrast enhancement boost of the equilibrium phase; NA: Not available.

Table 4 Distribution of subjective image scoring for different protocols by the two radiologists

Blood vessel visualization (1/2/3/4)	Reviewer 1	Reviewer 2	Agreement (κ)
Portal vein
PVP	0/0/0/52	0/0/0/52	NA
EP	0/0/2/50	0/0/1/51	0.66
CE boost (EP)	0/0/0/52	0/0/0/52	NA
Segmental branch of the portal vein
PVP	0/0/2/50	0/0/1/51	0.66
EP	1/2/39/10	1/4/35/12	0.66
CE boost (EP)	0/2/2/48	0/2/3/47	0.64
Lesion conspicuity (1/2/3/4)
PVP	0/6/21/25	0/6/29/17	0.43
EP	1/6/26/19	1/5/28/18	0.81
CE boost (EP)	0/3/15/34	0/2/14/36	0.38
Image noise (1/2/3/4)
PVP	0/0/10/42	0/0/6/46	0.71
EP	0/0/10/42	0/0/6/46	0.71
CE boost (EP)	0/2/41/9	0/2/40/10	0.84

PVP: Portal vein phase; EP: Equilibrium phase; CE-boost (EP): Contrast enhancement boost of the equilibrium phase; NA: Not available.