Magnetic Resonance Imaging Guided Radiation Therapy for Splenomegaly: Clinical Experiences and Technical Tips

Splenomegaly is a common manifestation in chronic lymphoid and myeloid malignancies. Although splenectomy is the preferred treatment for symptomatic splenomegaly, it carries significant risks. Radiation therapy (RT) has traditionally been considered a palliative option. This study explores the use of magnetic resonance guided radiation therapy(MRgRT) for splenic irradiation (SI) in patients with myelofibrosis (MFI) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN).

This single-center retrospective analysis includes patients with MFI and MDS/MPN who underwent MRgRT SI between 2018 and 2022. Ten 1 Gy fractions were delivered to the planning target volume (spleen + 3/5mm margin). An adaptive online/offline strategy has been used to reduce the dose to healthy organs. Dosimetric data and clinical outcomes, including pain relief, gastrointestinal symptoms, and hematological values, were assessed.

Twelve patients completed SI without interruption, with supportive transfusions as needed for cytopenias. Pain and gastrointestinal symptom relief was observed in most cases. The mean percentage reduction in spleen volume was 53.61%, with an average craniocaudal extension reduction of 77.78%. Twenty-nine (24.2%) of 120 fractions were online adapted, and 14 (11.7%) were replanned offline. Nonhematological toxicities were not reported. At a median follow-up of 12.9 months, 6 patients died, whereas 9 patients underwent hematopoietic cell transplantation, with 6 of them surviving.

This study demonstrates MRgRT SI feasibility in MFI and MDS/MPN patients, offering symptom relief and significant spleen volume reduction. Real-time setup verification and adaptive planning allowed for tailored treatment with reduced margins, minimizing healthy tissue exposure. Larger prospective studies with longer follow-ups are needed to further validate its efficacy and safety.