Evaluation of Treatment Response Using Diffusion-Weighted MRI in Metastatic Spines

Lee, Jang Jin; Shin, Sei One

Abstract

BACKGROUND: The purpose of this study was to evaluated the usefulness of diffusion-weighted magnatic resonance imaging for monitoring the response to radiation therapy in metastatic bone marrow of the spines. MATERIALS AND METHOD: Twenty-one patients with metastatic bone marrow of the spine were examined with MRI. Diffusion-weighted and spin-echo MRI were performed in 10 patients before and after radiation therapy with or without systematic chemotherapy, and performed in 11 patiemts after radiation therapy alone. Follow up spin-echo and diffusion-weighted MRI were obtained at 1 to 6 months after radiation therapy according to patients' condition. The diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession(PSIF). Signal intensity changes of the metastatic bone marrows before and after radiation therapy on conventional spin-echo sequence MRI and diffusion-weighted MRI were evaluated. Bone marrow contrast ratios and signal-to-noise ratio before and after radiation therapy of diffusion-weighted MRI were analyzed.
RESULTS
All metastatic bone marrow of the spinal bodies were hyperintense to normal bone marrow of the spinal bodies on pretreatment diffusion-weighted MRI and positive bone marrow contrast ratio(p<0.001). and hypointense to normal spinal bodies on posttreatment diffusion-weighted MRI and negative bone marrow contrast ratio(p<0.001). The signal to noise ratio after treatment decreased comparing with those of pretreatment. Decreased signal intensity of the metastatic bone marrows on diffusion-weighted MRI began to be observed at average more than one month after the initiation of the radiation therapy.
CONCLUSION
tThese results suggest that diffusion-weighted MRI would be an excellent method for monitoring the response to therapy of metastatic bone marrow of the spinal bodies. However, must be investigated in a larger series of patients with longer follow up period.