LAUSR

AbstractObjectivesWe aimed to identify features that differentiate hepatic microabscess from hepatic metastasis on gadoxetic acid-enhanced MRI in patients with periampullary cancer.MethodsWe included 72 patients (31 patients with 83 hepatic microabscesses and 41 patients with 71 hepatic metastases) who had a history of periampullary cancer and underwent gadoxetic acid-enhanced MRI. Image analysis was performed for margin, signal intensity, rim enhancement, perilesional hyperaemia, pattern on DWI and dynamic phases, and size discrepancy between sequences by consensus of two observers.ResultsMultivariate analysis revealed that the following significant parameters favour microabscess: a history of bile duct cancer, perilesional hyperaemia, persistent arterial rim enhancement through the transitional phase (TP), and size discrepancy between T1WI and T2WI and between T1WI and hepatobiliary phase image (HBPI). The diagnostic accuracy for microabscess was highest (90.9%) when showing a size discrepancy ≥30% between T1WI and HBPI or persistent arterial rim enhancement through the TP. When the lesion was positive for both these variables, specificity reached 100%.ConclusionThe combination of a size discrepancy between T1WI and HBPI and persistent arterial rim enhancement through the TP represents a reliable MRI feature for distinguishing between hepatic microabscess and metastasis in patients with periampullary cancer.Key points• Gadoxetic acid-enhanced MRI is useful for distinguishing hepatic microabscess from metastasis. • Hepatic microabscess showed significant size discrepancy ≥30% between T1WI and HBPI. • Arterial rim enhancement persistent through the TP indicates hepatic microabscess.