Initial evaluation of hepatic T1 relaxation time as an imaging marker of liver disease associated with autosomal recessive polycystic kidney disease (ARPKD).

Autosomal recessive polycystic kidney disease (ARPKD) is a potentially lethal multi-organ disease affecting both the kidneys and the liver. Unfortunately, there are currently no non-invasive methods to monitor liver disease progression in ARPKD patients, limiting the study of potential therapeutic interventions. Herein, we perform an initial investigation of T₁ relaxation time as a potential imaging biomarker to quantitatively assess the two primary pathologic hallmarks of ARPKD liver disease: biliary dilatation and periportal fibrosis in the PCK rat model of ARPKD. T₁ relaxation time results were obtained for five PCK rats at 3 months of age using a Look-Locker acquisition on a Bruker BioSpec 7.0 T MRI scanner. Six three-month-old Sprague-Dawley (SD) rats were also scanned as controls. All animals were euthanized after the three-month scans for histological and biochemical assessments of bile duct dilatation and hepatic fibrosis for comparison. PCK rats exhibited significantly increased liver T₁ values (mean ± standard deviation = 935 ± 39 ms) compared with age-matched SD control rats (847 ± 26 ms, p = 0.01). One PCK rat exhibited severe cholangitis (mean T₁ = 1413 ms), which occurs periodically in ARPKD patients. The observed increase in the in vivo liver T₁ relaxation time correlated significantly with three histological and biochemical indicators of biliary dilatation and fibrosis: bile duct area percent ( R = 0.85, p = 0.002), periportal fibrosis area percent ( R = 0.82, p = 0.004), and hydroxyproline content ( R = 0.76, p = 0.01). These results suggest that hepatic T₁ relaxation time may provide a sensitive and non-invasive imaging biomarker to monitor ARPKD liver disease. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]