MRI findings of newly present benign focal hepatic observations following chemotherapy: distinct features in early- and late-term follow-up.

Objective: To evaluate gadoxetic acid-enhanced (Gd-EOB-DTPA) MRI features of newly detected benign focal hepatic observations after chemotherapy.

Methods: In this retrospective single-center case-control study, we enrolled a cohort of 43 cancer patients with 93 newly detected benign focal hepatic observations after chemotherapy between January 2010 and December 2020. We evaluated several parameters including the delay of occurrence after chemotherapy, imaging features, and imaging follow-up. These parameters were compared with those observed in a control group comprising 34 patients with 93 hepatic metastases.

Results: For focal hepatic observations occurring at early-term follow-up (delay of occurrence after chemotherapy, median 3 months, range 1-6 months) with 22 patients encompassing 45 lesions, most lesions exhibited an ill-defined margin on HBP images (64.4%), negative on diffusion-weighted images (84.4%), mottled hypo-intensity on hepatobiliary phase images (88.9%), and undistorted vessels traversing the lesions (80.0%). Follow-up imaging indicated that 91.9% of these lesions resolved within 4-20 months. For focal hepatic observations occurring at late-term follow-up (delay of occurrence after chemotherapy, median 34 months, range 12-60 months) with 21 patients encompassing 48 lesions, which were diagnosed as focal nodular hyperplasia (FNH)-like lesions based on MRI features. A hepatobiliary ring enhancement was observed in 56.3% of lesions, and 66.7% of patients showed an increase in lesion size and/or number during follow-up imaging.

Conclusion: Focal hepatic observations occurring at early-term and late-term follow-ups after chemotherapy have distinctive imaging features at Gd-EOB-DTPA-MRI. Early-term focal observations tend to resolve spontaneously, whereas FNH-like lesions can increase in size and number during follow-up.

Key points: Question Focal benign liver lesions related to chemotherapy-induced hepatic injury were reported in recent years, often leading to confusion with metastasis and resulting in misdiagnosis. Findings Chemotherapy-induced focal hepatic observations identified during early- and late-term follow-up exhibit distinct imaging characteristics on Gd-EOB-DTPA-MRI and demonstrate varying temporal changes. Clinical relevance Chemotherapy-induced hepatic observations can be differentiated from metastasis based on Gd-EOB-DTPA MRI findings and their temporal changes. A deeper understanding of their findings can avoid unnecessary biopsies or surgical resections.