Gadoxetic acid-enhanced MRI and diffusion-weighted imaging for the detection of colorectal liver metastases after neoadjuvant chemotherapy.

Objectives: To investigate the diagnostic performance of gadoxetic acid-enhanced MRI including diffusion-weighted imaging (DWI) for the detection of colorectal liver metastases (CRLMs) after neoadjuvant chemotherapy (NAC).
Methods: Our study population comprised 77 patients with 140 CRLMs who underwent gadoxetic acid-enhanced MRI within 1 month prior to surgery: group A (without NAC, n = 38) and group B (with NAC, n = 39). Two radiologists independently assessed all MR images and graded their diagnostic confidence for CRLM on a 5-point scale. Diagnostic accuracy, sensitivity and positive predictive values (PPV) were calculated and compared between the two groups.
Results: Diagnostic accuracy of gadoxetic acid-enhanced MRI in group B was slightly lower than in group A, but a statistically significant difference was not observed (observer 1: A z, 0.926 in group A, 0.905 in group B; observer 2: A z, 0.944 in group A, 0.885 in group B; p > 0.05). Sensitivity and PPV of group B were comparable to those of group A (observer 1: sensitivity = 93.5 % vs. 93.6 %, PPV = 95.1 % vs. 86.9 %; observer 2: sensitivity = 96.8 % vs. 91.0 %; PPV = 90.0 % vs. 89.7 %; all p > 0.05).
Conclusions: Gadoxetic acid-enhanced MRI including DWI provided good diagnostic performance with high sensitivity (>90 %) for the detection of CRLMs, regardless of the influence of NAC.
Key Points: • Gadoxetic acid-enhanced MRI including DWI shows high sensitivity for CRLMs. • Chemotherapy does not influence the diagnostic performance of liver MRI for CRLMs. • Gadoxetic acid-enhanced MRI can be used for evaluation of CRLMs after NAC.