Fat composition changes in bone marrow during chemotherapy and radiation therapy.

Area of Science:

• Oncology
• Radiology
• Hematology

Background:

• Chemoradiation therapy can cause significant toxicity.
• Bone marrow is a critical site for blood cell production and is susceptible to radiation and chemotherapy damage.
• Assessing bone marrow changes may help predict or understand treatment-related toxicities.

Purpose of the Study:

• To quantify changes in bone marrow fat fraction using magnetic resonance imaging (MRI).
• To determine the association between bone marrow fat fraction changes and peripheral blood cell counts.
• To evaluate differences in fat fraction changes based on treatment intensity and vertebral region.

Main Methods:

• Prospective study of 19 patients undergoing chemoradiation therapy.
• MRI was used to measure proton density fat fraction (PDFF) at baseline, midtreatment, and posttreatment.
• Mixed effects modeling analyzed PDFF changes by time, treatment intensity, and vertebral region, controlling for radiation dose.

Main Results:

• Highly myelotoxic treatments led to significant increases in bone marrow PDFF (%), particularly in the lower spine (L4-S2) and mid-thoracic regions (T10-L3).
• Less myelotoxic treatments did not show significant PDFF changes.
• Significant correlations were observed between changes in PDFF and reductions in white blood cell (WBC) and absolute neutrophil counts.

Conclusions:

• MRI-based fat quantification is sensitive to bone marrow composition changes induced by chemoradiation.
• Bone marrow fat fraction changes are associated with hematologic toxicity.
• Findings support the development of bone marrow-sparing treatment planning to mitigate risks.