Weekly MR-DWI/T1WI for early treatment response assessment of hepatic metastasis from ampullary carcinoma treated with gemcitabine, cisplatin, and durvalumab: A case report

Ampullary carcinoma is a rare gastrointestinal malignancy with a poor prognosis once hepatic metastasis develops. Although combination immunochemotherapy with gemcitabine, cisplatin, and durvalumab (GCD) therapy has recently demonstrated improved survival outcomes, early and accurate assessment of therapeutic response remains challenging. Magnetic resonance (MR) diffusion-weighted imaging (DWI), combined with T1-weighted imaging (T1WI), may provide a sensitive and noninvasive means of evaluating early treatment effects. A 68-year-old man underwent laparoscopic pancreaticoduodenectomy for ampullary carcinoma with lymph node metastasis. Despite adjuvant S-1 chemotherapy, a solitary 18-mm liver metastasis developed 6 months postoperatively. GCD therapy was initiated, and weekly MR-DWI/T1WI was performed for response assessment. At treatment initiation, the metastatic lesion had increased to 25 mm, demonstrating high signal intensity on DWI and low signal intensity on T1WI. Following treatment, rapid tumor regression was observed radiologically. Tumor volume decreased from 5.06 mm³ at baseline to 0.83 mm³ at 6 weeks and 0.53 mm³ at 10 weeks. FDG PET-CT and contrast-enhanced CT confirmed a complete radiological response after three treatment cycles. The patient remains recurrence-free 24 months after treatment completion. This case highlights the potential clinical value of weekly MR-DWI/T1WI for early and detailed assessment of treatment response during GCD therapy. Intensive MRI surveillance may support timely clinical decision-making and provide useful functional imaging biomarkers in selected patients with metastatic ampullary carcinoma.