Time-domain NMR enables non-invasive longitudinal monitoring of intrahepatic cholangiocarcinoma in mice

Intrahepatic cholangiocarcinoma (iCCA) is an aggressive biliary malignancy for which longitudinal non-invasive monitoring remains challenging in preclinical models. Using time-domain nuclear magnetic resonance (TD-NMR), we characterized disease-associated whole-body composition changes in the pNICD/pAKT hydrodynamic injection mouse model of iCCA. Tumor-bearing mice developed a progressive increase in whole-body fluid relative to body weight and a decrease in fat mass relative to body weight compared with tumor-free controls, despite stable total body weight. Ultrasound confirmed the presence of cystic hepatic lesions but was used as a qualitative structural assessment rather than a serial quantitative comparator. Day-specific receiver operating characteristic analyses showed that fluid/weight and fat mass/weight ratios increasingly discriminated iCCA-bearing from tumor-free mice as disease progressed. Exploratory within-animal analyses further showed that absolute body-composition ratios, particularly fluid/weight ratio, distinguished terminal clinical assessments from predefined earlier assessments. Daily relative changes in normalized parameters showed more variable performance and did not improve classification of terminal clinical status. These findings identify TD-NMR-derived fluid and fat ratios as practical longitudinal markers of physiological changes associated with iCCA progression in this model. Direct quantification of ascites and prospective validation in independent cohorts will be required before deriving generalizable diagnostic or humane-endpoint thresholds.