Evaluation of Occult Liver Metastases in Pancreatic Adenocarcinoma by Diffusion-Weighted Related Magnetic Resonance Imaging.

Background: Occult liver metastases in patients with pancreatic ductal adenocarcinoma (PDAC) affects treatment strategies and prognosis. Diffusion-weighted imaging (DWI), including non-Gaussian DWI may help to evaluate tumor biological behavior.

Purpose: To evaluate the diagnostic value of DWI parameters in predicting occult liver metastases in patients with PDAC.

Study type: Prospective.

Population: 115 participants with pathologically confirmed PDAC (male = 71, mean age = 59.8 ± 9.9 years). Occult liver metastasis was defined as those detected by CT or MRI within 6 months of pancreatectomy.

Field strength/sequence: DWI, intravoxel incoherent motion (IVIM) imaging and diffusion kurtosis imaging (DKI) echo planar imaging sequences at 1.5 T.

Assessment: Apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), mean apparent diffusion (MD) and mean kurtosis (MK) were measured. In addition, age, sex, body mass index, neutrophil-to-lymphocyte ratio (NLR) and carbohydrate antigen 19-9 (CA 19-9) level were recorded.

Statistical tests: Logistic regression analysis, area under the receiver operating characteristic curve (AUC), DeLong test. Two tailed P value < 0.05 was considered significant. Results 23 of 115 (20%) participants had occult liver metastases. Multivariable analysis revealed D [odds ratio (OR) = 0.220], NLR (OR = 1.391) and CA19-9 level (OR = 1.002) were independent risk factors for occult liver metastases. The AUCs were 0.772 for the combination of NLR and CA19-9 level, and 0.848 for the combination of D, NLR and CA19-9 level, without significant difference between the two models (P = 0.055).

Data conclusion: A combination of D, NLR and CA19-9 level may be useful in the prediction of occult liver metastases in patients with PDAC.

Evidence level: 2.

Technical efficacy: Stage 2.