Magnetic resonance imaging bias field correction improves tumor prognostic evaluation after transcatheter arterial chemoembolization for liver cancer

Table 1 Analysis of general patient information, n (%)

Item	Statistic
Total number of patients, baseline	105
Age
< 65 years old	74 (70.48)
≥ 65 years old	31 (29.52)
Gender
Male	78 (74.29)
Female	27 (25.71)
Survival status at analysis
Alive	24 (22.86)
Deceased	81 (77.14)
Follow-up time (months)
Mean (range)	17.32 (0.21-142.55)
Median (interquartile range)	10.95 (4.23-21.32)
Etiology
Hepatitis B virus	89 (84.76)
Hepatitis C virus	9 (8.57)
Alcoholic liver disease	7 (6.66)
Cryptogenic liver cancer	1(0.95)
Cirrhosis	71 (67.62)
Barcelona Clinic Liver Cancer staging
B	31 (29.52)
C	71 (67.62)
D	3 (2.86)
Child-Pugh classification
A	70 (66.67)
B	34 (32.38)
C	1 (0.95)
ECOG performance status
0	58 (55.24)
1	41 (39.05)
2	4 (3.81)
3	2 (1.90)
Number of tumors
1	19 (18.10)
2	20 (19.05)
3	12 (11.43)
More than 4	54 (51.43)
Tumor size (cm)
Mean (range)	8.72 (1.6-19.8)
Median (interquartile range)	8.15 (5.2-11.8)
Portal vein invasion
Yes	44 (41.90)
No	61 (58.10)
Extrahepatic metastasis
Yes	9 (8.57)
No	96 (91.43)
TACE Type
Lipiodol	69 (65.71)
Drug-eluting beads	36 (34.29)
Number of TACE treatments
1	50 (47.62)
2	19 (18.10)
3	14 (13.33)
4 or more than 4	22 (20.95)

ECOG: Eastern Cooperative Oncology Group; TACE: Transcatheter arterial chemoembolization.

Table 2 Comparison of effective tumor volume before and after transcatheter arterial chemoembolization treatment with and without magnetic resonance bias field correction

Variables baseline ETV	Mean (interval) (cm3)		P value
	No MR bias field correction	With MR bias field correction
After TACE treatment	825.632 (63.523-3563.126)	505.235 (142.352-1292.223)	< 0.001
ETV	632.523 (47.235-3382.532)	325.236 (110.135-1018.516)	< 0.001

ETV: Effective tumor volume; TACE: Transcatheter arterial chemoembolization; MR: Magnetic resonance.

Table 3 Hazard ratios of baseline effective tumor volume, absolute effective tumor volume change, and effective tumor volume% with and without magnetic resonance bias field correction

Variable	Not using bias field correction		Use bias field correction
	Hazard ratio	P value	Hazard ratio	P value
Baseline ETV	1.063 (1.031-1.095)	< 0.001	1.165 (1.069-1.268)	< 0.001
Absolute ETV change	1.012 (0.985-1.042)	0.481	1.040 (0.935-1.160)	0.512
ETV%	1.005 (0.981-1.030)	0.793	0.665 (0.538-0.825)	< 0.001

ETV: Effective tumor volume.

Table 4 Survival time of different effective tumor volume groups before transcatheter arterial chemoembolization treatment

Percentage (%)	< 415 cm3		≥ 415 cm3
	Survival time (months)	95%CI	Survival time (months)	95%CI
25	10.523	4.862-15.235	3.862	1.523-5.862
50	18.523	14.862-29.635	8.926	5.923-10.832
75	35.862	22.523-45.236	15.235	10.523-19.862

CI: Confidence interval.

Table 5 Survival time of different effective tumor volume% groups before and after transcatheter arterial chemoembolization treatment

Percent (%)	< 0.414		≥ 0.414
	Survival time (months)	95%CI	Survival time (months)	95%CI
25	3.235	1.523-5.862	10.523	6.523-14.862
50	9.235	5.862-12.523	17.862	13.926-20.635
75	15.235	10.235-31.523	29.635	19.862-72.523

CI: Confidence interval.

Table 6 Results of baseline effective tumor volume single factor and multi factor analysis using bias field correction

Variables	Control	Single factor		Multi-factor
Age	Increase by 1	Hazard ratio	P value	Hazard ratio	P value
Pre-treatment ETV (cm³)	≥ 415 vs < 415	1.018 (0.982-1.036)	0.453	1.008 (0.964-1.032)	0.832
Gender	Female vs male	1.982 (1.212-3.236)	0.012	1.442 (0.823-2.558)	0.178
Child-Pugh classification	Class A vs (class B or C)	0.736 (0.438-1.264)	0.234	0.728 (0.416-1.282)	0.273
BCLC staging	Stage B vs (stage C or D)	0.423 (0.252-0.668)	< 0.001	0.432 (0.256-0.702)	< 0.001
Type of TACE	Control	0.523 (0.318-0.852)	0.013	0.538 (0.318-0.916)	0.023
Variables	Lipiodol vs DEB-TACE	1.178 (0.723-1.916)	0.548	1.016 (0.612-1.682)	0.976

ETV: Effective tumor volume; BCLC: Barcelona Clinic Liver Cancer; DEB-TACE: Drug-eluting bead transcatheter arterial chemoembolization.

Table 7 Single factor and multi factor analysis results of effective tumor volume% using bias field correction

Variable	Control	Single factor		Multi-factor
		Hazard ratio	P value	Hazard ratio	P value
Age	Increase by 1	1.018 (0.982-1.036)	0.453	1.008 (0.964-1.032)	0.812
ETV reduction rate	≥ 41% vs < 41%	0.523 (0.346-0.918)	0.018	0.412 (0.238-0.678)	< 0.001
Gender	Female vs male	0.736 (0.438-1.264)	0.234	0.748 (0.432-1.328)	0.324
Child-Pugh	Class A vs (class B or C)	0.423 (0.252-0.668)	< 0.001	0.298 (0.162-0.502)	< 0.001
BCLC staging	Stage B vs (stage C or D)	0.523 (0.318-0.852)	0.013	0.578 (0.332-0.976)	0.045
TACE type	Lipiodol vs DEB-TACE	1.178 (0.723-1.916)	0.548	0.832 (0.482-1.396)	0.464

ETV: Effective tumor volume; BCLC: Barcelona Clinic Liver Cancer; DEB-TACE: Drug-eluting bead transcatheter arterial chemoembolization.