Evaluation of the mean and entropy of apparent diffusion coefficient values in chronic hepatitis C: correlation with pathologic fibrosis stage and inflammatory activity grade.
OBJECTIVE
To determine whether mean and entropy apparent diffusion coefficient (ADC) values obtained at diffusion-weighted (DW) magnetic resonance (MR) imaging can help detect and stage histopathologic liver fibrosis and grade inflammation activity in patients with chronic hepatitis C.


METHODS
This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. The study included 55 patients with focal hepatic lesions and either chronic hepatitis C (n = 43) or normal hepatic function (control subjects) (n = 12). Mean and entropy of volume histograms were generated in four cubic regions of interest placed in the right hepatic lobe of ADC map images, which were obtained at echo-planar DW MR imaging (gradient factor b values of 0 and 1000 sec/mm(2)). These two parameters (mean and entropy ADC) were compared by using METAVIR histopathologic liver fibrosis and inflammatory activity scores. Statistical analysis was performed with the Kruskal-Wallis test and receiver operating characteristic curves.


RESULTS
The mean ADC decreased with an increase in the fibrosis stage or inflammatory activity grade, and the entropy ADC increased with an increase in the fibrosis stage or inflammatory activity grade (P < .001 for all comparisons, Kruskal-Wallis test). The area under the receiver operating characteristic curve (A(z)) for the mean ADC was statistically significant in the differentiation of fibrosis stage or inflammatory activity grade (A(z), 0.807-0.926; P < .001 for all comparisons). Entropy of ADC was helpful for classifying normal from abnormal fibrosis stage or inflammatory activity grade (A(z) for both parameters, 0.937; P < .001).


CONCLUSIONS
Assessment of a combination of mean ADC and entropy ADC in patients with chronic hepatitis C is more accurate for predicting pathologic hepatic fibrosis stage and inflammatory activity grade and helpful for detecting early fibrotic or inflammatory activity when compared with assessment of mean ADC alone.
Department of Radiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011 Japan. kimichan@med.kurume-u.ac.jp
Kiminori
K
Fujimoto
Tatsuyuki
T
Tonan
Sanae
S
Azuma
Masayoshi
M
Kage
Osamu
O
Nakashima
Takeshi
T
Johkoh
Naofumi
N
Hayabuchi
Koji
K
Okuda
Takumi
T
Kawaguchi
Michio
M
Sata
Aliya
A
Qayyum
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019698:Hepatitis C, Chronic / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric