title: Magnetic resonance-guided focused ultrasound for the treatment of painful bone metastases: role of apparent diffusion coefficient (ADC) and dynamic contrast enhanced (DCE) MRI in the assessment of clinical outcome.
abstract: OBJECTIVE
  To assess the correlation between functional MRI, including ADC values obtained from DWI and DCE, and clinical outcome in patients with bone metastases treated with MRgFUS.
  
  
  METHODS
  Twenty-three patients with symptomatic bone metastases underwent MRgFUS treatment (ExAblate 2100 system InSightec) for pain palliation. All patients underwent clinical and imaging follow-up examinations at 1, 3 and 6 months after treatment. Visual Analog Scale (VAS) score was used to evaluate treatment efficacy in terms of pain palliation while ADC maps obtained by DWI sequences, and DCE data were used for quantitative assessment of treatment response at imaging. Spearman Correlation Coefficient Test was calculated to assess the correlation between VAS, ADC and DCE data.
  
  
  RESULTS
  All treatments were performed successfully without adverse events. On the basis of VAS score, 16 (69.6 %) patients were classified as complete clinical responders, 6 (26.1 %) as partial responders and only one (4.3 %) was classified as a non-responder. The mean VAS score decreased from 7.09 ± 1.8 at baseline to 2.65 ± 1.36 at 1 month, 1.04 ± 1.91 at 3 months and 1.09 ± 1.99 at 6 months (p < 0.001). Baseline mean ADC value of treated lesions was 1.05 ± 0.15 mm2/s, increasing along follow-up period (1.57 ± 0.27 mm2/s 1st month; 1.49 ± 0.3 mm2/s 3rd month; 1.45 ± 0.32 mm2/s 6th month, p < 0.001). Non perfused volume (NPV) was 46.4 at 1 month, 45.2 at 3 months and 43.8 at 6 months. Spearman Coefficient demonstrated a statistically significant negative correlation between VAS and ADC values (ρ = -0.684; p = 0.03), but no significant correlation between VAS and NPV (ρ = 0.02216, p = 0.9305). Among other DCE data, Ktrans significantly changed in complete responders (3 months Ktrans = 2.14/min; -ΔKt = 52.65 % p < 0.01) and was not significantly different in partial responders (3 months Ktrans 0.042/min; ΔKt = 11.39 % p > 0.01).
  
  
  CONCLUSIONS
  In patients with painful bone metastases treated with MRgFUS, ADC and Ktrans variation observed in the ablated lesions correlate with VAS values and may play a role as objective imaging marker of treatment response.
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy. michele.anzidei@gmail.com.
authors: Michele
authors: M
authors: Anzidei
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
authors: Alessandro
authors: A
authors: Napoli
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.|Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Viale Regina Elena 291, Rome, Italy.
authors: Beatrice
authors: B
authors: Sacconi
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
authors: Fabrizio
authors: F
authors: Boni
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
authors: Vincenzo
authors: V
authors: Noce
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
authors: Michele
authors: M
authors: Di Martino
authors: Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari, Polo di Monserrato, Cagliari, Italy.
authors: Luca
authors: L
authors: Saba
authors: Department of Radiological, Oncological and Anatomopathological Sciences, Radiology, "Sapienza" University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
authors: Carlo
authors: C
authors: Catalano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000601:surgery*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D057086:High-Intensity Focused Ultrasound Ablation; D006801:Humans; D008017:Life Expectancy; D008279:Magnetic Resonance Imaging; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059408:Pain Management; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media
keywords: ADC; Apparent diffusion coefficient; Bone metastases; DCE; DWI; Diffusion-weighted imaging; Dynamic contrast enhanced MRI; MR-guided Focused Ultrasound; MRgFUS