Purpose: To evaluate prognostic values of clinical and diffusion-weighted magnetic resonance imaging-derived intravoxel incoherent motion (IVIM) parameters in patients undergoing primary radioembolization for metastatic breast cancer liver metastases.
Subjects and methods: A total of 21 females (mean age 54 years, range 43-72 years) with liver-dominant metastatic breast cancer underwent standard liver magnetic resonance imaging (1.5 T, diffusion-weighted imaging with b-values of 0, 50, and 800 s/mm(2)) before and 4-6 weeks after radioembolization. The IVIM model-derived estimated diffusion coefficient D' and the perfusion fraction f' were evaluated by averaging the values of the two largest treated metastases in each patient. Kaplan-Meier and Cox regression analyses for overall survival (OS) were performed. Investigated parameters were changes in f'- and D'-values after therapy, age, sex, Eastern Cooperative Oncology Group (ECOG) status, grading of primary tumor, hepatic tumor burden, presence of extrahepatic disease, baseline bilirubin, previous bevacizumab therapy, early stasis during radioembolization, chemotherapy after radioembolization, repeated radioembolization and Response Evaluation Criteria in Solid Tumors (RECIST) response at 6-week follow-up.
Results: Median OS after radioembolization was 6 (range 1.5-54.9) months. In patients with therapy-induced decreasing or stable f'-values, median OS was significantly longer than in those with increased f'-values (7.6 [range 2.6-54.9] vs 2.6 [range 1.5-17.4] months, P<0.0001). Longer median OS was also seen in patients with increased D'-values (6 [range 1.6-54.9] vs 2.8 [range 1.5-17.4] months, P=0.008). Patients with remission or stable disease (responders) according to RECIST survived longer than nonresponders (7.2 [range 2.6-54.9] vs 2.6 [range 1.5-17.4] months, P<0.0001). An ECOG status ≤1 resulted in longer median OS than >1 (7.6 [range 2.6-54.9] vs 1.7 [range 1.5-4.5] months, P<0.0001). Pretreatment IVIM parameters and the other clinical characteristics were not associated with OS. Classification by f'-value changes and ECOG status remained as independent predictors of OS on multivariate analysis, while RECIST response and D'-value changes did not predict survival.
Conclusion: Following radioembolization of breast cancer liver metastases, early changes in the IVIM model-derived perfusion fraction f' and baseline ECOG score were predictive of patient outcome, and may thus help to guide treatment strategy.
Keywords: DWI; IVIM; MRI; breast cancer; radioembolization; selective internal radiation therapy.