Table of Contents
Journal of Radiotherapy
Volume 2014 (2014), Article ID 698127, 8 pages
http://dx.doi.org/10.1155/2014/698127
Clinical Study

Assessing Response to Radiation Therapy Treatment of Bone Metastases: Short-Term Followup of Radiation Therapy Treatment of Bone Metastases with Diffusion-Weighted Magnetic Resonance Imaging

1Department of Internal Clinical and Experimental Medicine, Second University of Naples, Piazza Miraglia 4, 80100 Naples, Italy
2Assistential Department of Radiology, Radiotherapy and Nuclear Medicine, Second University of Naples, Piazza Miraglia 4, 80100 Naples, Italy

Received 17 October 2013; Revised 8 January 2014; Accepted 17 February 2014; Published 26 March 2014

Academic Editor: Samer Ezziddin

Copyright © 2014 Salvatore Cappabianca et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study examined the usefulness of diffusion-weighted (DW) Magnetic Resonance Imaging (MRI) in monitoring bone metastases response to radiation therapy in 15 oligometastatic patients. For each metastasis, both mean apparent diffusion coefficient (ADC) changes and high b-value DW metastasis/muscle signal intensity ratio (SIR) variations were evaluated at 30 ± 5 days and 60 ± 7 days after the end of treatment. On baseline DW-MRI, all bone metastases were hyperintense and had signal intensities higher than normal bone marrow on calculated ADC maps. At follow-up evaluations, 4 patterns of response were identified: (I) decreased high b-value DW SIR associated with increased mean ADC (83.3% of cases); (II) increased mean ADC with no change of high b-value DW SIR (10% of cases); (III) decreased both high b-value DW SIR and mean ADC (3.3% of cases); (IV) a reduction in mean ADC associated with an increase in high b-value DW SIR compared to pretreatment values (3.3% of cases). Patterns (I) and (II) suggested a good response to therapy; pattern (III) was classified as indeterminate, while pattern (IV) was suggestive of disease progression. This pattern approach may represent a useful tool in the differentiation between treatment-induced necrosis and highly cellular residual tumor.