Intravoxel incoherent motion diffusion-weighted imaging for the assessment of renal injury in cirrhotic patients.

BACKGROUND: Renal dysfunction is a common complication in patients with cirrhosis, and early detection is crucial for timely intervention and treatment. Intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) serves as a non-invasive imaging technique that provides valuable insights into tissue perfusion and diffusion changes, demonstrating significant superiority in assessing renal injury. This prospective study aimed to evaluate early renal injury in patients with cirrhosis using IVIM DWI and to explore the correlation of IVIM parameters with the severity of liver cirrhosis based on the Child-Pugh classification.

METHODS: Sixty-four cirrhotic patients and 30 healthy subjects underwent IVIM on a 3.0-T magnetic resonance imaging (MRI). Diffusion coefficient (ADCslow), pseudo-diffusion coefficient (ADCfast), and perfusion fraction (f) were derived from the bi-exponential model. In the control group, IVIM-derived parameters for both renal cortex and medulla were compared between right and left kidneys. Subsequently, IVIM-derived renal cortical and medullary parameters were compared between the cirrhotic and control groups. Additionally, within the cirrhotic group, IVIM-derived renal parameters were correlated with the Child-Pugh classification.

RESULTS: In the control group, bilateral renal IVIM parameters (ADCslow, ADCfast, and f) showed no significant differences between left and right kidneys (all P>0.05), justifying the use of averaged values for subsequent analysis. Comparative assessment between cirrhotic patients and controls revealed significantly lower renal cortical ADCfast (P=0.033) and f values (P=0.049) in the cirrhotic group, while ADCslow did not differ significantly (P=0.846). In the renal medulla, cirrhotic patients exhibited reduced ADCfast (P=0.043) compared with controls, with no differences in ADCslow or f (P=0.638 and 0.173, respectively). Notably, renal cortical ADCfast demonstrated a significant inverse correlation with Child-Pugh classification (R=-0.406, P=0.001), being higher in Child-Pugh A vs. B (P=0.032) and A vs. C (P=0.019) patients, whereas ADCslow and f showed no correlation with hepatic function grade (P=0.817 and 0.191). Similarly, renal medullary ADCfast correlated inversely with Child-Pugh classification (R=-0.251, P=0.045), with higher values in class A vs. B (P=0.017), but no differences between class A vs. C (P=0.052) or B vs. C (P=0.448). ADCslow and f values in both cortical and medullary regions remained non-significant across Child-Pugh classification (all P>0.05).

CONCLUSIONS: IVIM DWI non-invasively assesses early renal injury in cirrhotic patients, with reduced renal perfusion correlating with liver cirrhosis severity.