Liver diffusivity in healthy volunteers and patients with chronic liver disease: comparison of breathhold and free-breathing techniques.
OBJECTIVE
To compare liver ADC obtained with breathhold and free-breathing diffusion weighted imaging (DWI) in healthy volunteers and patients with liver disease.


METHODS
Twenty-eight subjects, 12 healthy volunteers and 16 patients (9 NAFLD, 7 chronic active HCV), underwent breathhold (BH) and free-breathing (FB) DWI MRI at 1.5 Tesla. Pearson's correlation coefficient was used to determine correlation while paired t-tests assessed differences between BH and FB ADC. Estimated bias was calculated using the Bland-Altman method.


RESULTS
Liver ADC (×10(-3) mm(2) /s) was lower on BH for all groups (mean difference 0.36 ± 0.20; P < 0.01). ADC was higher in healthy volunteers (BH 1.80 ± 0.18; FB 2.24 ± 0.20) compared with NAFLD patients (BH 1.43 ± 0.27; FB 1.78 ± 0.28) (P < 0.001) and HCV patients (BH 1.63 ± 0.191; FB 1.88 ± 0.12). Overall correlation between BH and FB ADC was (r = 0.75), greatest in NAFLD (r = 0.90) compared with the correlation in HCV (r = 0.24) and healthy subjects (r = 0.34). Bland-Altman plots did not show agreement in mean absolute difference and estimated bias between subjects.


CONCLUSIONS
Correlation between BH and FB liver ADC is moderate indicating that BH and FB should not be used interchangeably. Additionally, the lower ADC values in BH versus FB should be accounted for when comparing different liver DWI studies.
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143-0628, USA.
Mamak
M
Eatesam
Susan M
SM
Noworolski
Phyllis C
PC
Tien
Michelle
M
Nystrom
Jennifer L
JL
Dodge
Raphael B
RB
Merriman
Aliya
A
Qayyum
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D058625:End Stage Liver Disease / Q000473:pathology*; D005234:Fatty Liver / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006526:Hepatitis C / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008099:Liver / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D065626:Non-alcoholic Fatty Liver Disease; D012119:Respiration