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 Salvatore Cappabianca, 1 Raffaella Capasso, 1 Fabrizio Urraro, 1 Andrea Izzo, 1 Antonio Raucci, 1 Rossella Di Franco, 2 and Antonio Rotondo 1 1 Department of Internal Clinical and Experimental Medicine, Second University of Naples, Piazza Miraglia 4, 80100 Naples, Italy 2 Assistential Department of Radiology, Radiotherapy and Nuclear Medicine, Second University of Naples, Piazza Miraglia 4, 80100 Naples, Italy Correspondence should be addressed to Rafaella Capasso; dott.ssacapasso@gmail.com 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. Tis 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. Tis study examined the usefulness of difusion-weighted (DW) Magnetic Resonance Imaging (MRI) in monitoring bone metastases response to radiation therapy in 15 oligometastatic patients. For each metastasis, both mean apparent difusion coefcient (ADC) changes and high b-value DW metastasis/muscle signal intensity ratio (SIR) variations were evaluated at 30 ± 5 days and 60 ± 7 days afer 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 identifed: (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 classifed as indeterminate, while pattern (IV) was suggestive of disease progression. Tis pattern approach may represent a useful tool in the diferentiation between treatment-induced necrosis and highly cellular residual tumor. 1. Introduction Bone metastases occur from 30% to 70% of all patients sufering from cancer and commonly involve the axial skele- ton [1, 2]. Breast, prostate, and lung cancers represent the main sources of bone metastases, with prostate and lung cancers being most common in males and breast cancer being most common in females [2]. Once bony metastases occur, cancer cure becomes impossible and in these cases radiation therapy, associated or not with systemic chemotherapy, may be performed for palliative intent [1, 3]. Terapy goals are to delay progression, palliate symptoms, improve quality of life, and achieve any possible survival beneft [3]. Currently, there are no universally accepted methods for evaluating the response to treatment, making it difcult to give patient the optimal management to minimize radiation dose and pre- vent recurrences [1, 3]. Bone scintigraphy (99mTc-methylene diphosphonate-MDP-bone scans) with plain radiographs or cross-sectional imaging, such as Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), and some- times 18F-fuoride Positron Emission Tomography (PET)/CT remain the commonest imaging methods, complementing one another in order to characterize and follow up bone mar- row metastases [1, 3, 4]. Although conventionally used, none Hindawi Publishing Corporation Journal of Radiotherapy Volume 2014, Article ID 698127, 8 pages http://dx.doi.org/10.1155/2014/698127