title: [Quantitative assessment of vasculature with DCE-MRI in nasopharyngeal carcinomas following radiotherapy and its value for efficacy evaluation].
abstract: OBJECTIVE
  To study the changes in quantitative kinetic parameters in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) during radiotherapy and their value for efficacy evaluation in patients with nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Twenty-four patients with NPC that had been pathologically confirmed as poorly differentiated squamous cell carcinoma underwent conventional MRI and DCE-MRI scans 1-2 days before radiotherapy (Pre-RT), during radiotherapy (RT 50 Gy), and upon completion of radiotherapy (RT 70 Gy). Based on the two-compartment model and using the arterial input function deconvolution technique, we calculated the quantitative kinetic parameters of DCE-MRI (K(trans), kep, and Ve) of the tumor tissues, examined the correlation between the tumor regression rate (RS0-50) and the parameters on Pre-RT and RT 50 Gy, and compared the parameters for RT 70 Gy among the groups with different prognosis.
  
  
  RESULTS
  The K(trans) value of the tumor tissue decreased after radiotherapy and showed a significant difference between Pre-RT and RT 70 Gy, but not between Pre-RT and RT 50 Gy. The kep value decreased and Ve value increased after radiotherapy. The tumor regression rate was found to be positively correlated with the K(trans) value for Pre-RT (P=0.005) but negatively with the K(trans) value for RT 50 Gy (P=0.001). During the follow-up for 3 years, 5 patients died and 3 patients had distant metastases. No statistical differences in K(trans), kep, or Ve were found between the groups with different prognosis.
  
  
  CONCLUSIONS
  The kinetic parameters in DCE-MRI, which vary significantly during radiotherapy, allow monitoring of tumor angiogenesis and vascular permeability and quantitative assessment of treatment efficacy for NPC. K(trans) value for Pre-RT and RT 50 Gy can serve as an indicator for early efficacy assessment of radiotherapy and for treatment adjustment, but its relation with the long-term outcomes awaits further study.
authors.affiliation: Department of Radiology, Xiangya Hospital, Central South University, Changsha 410008, China.E-mail: ouwenliao@163.com.
authors.forename: Weihua
authors.initials: W
authors.lastname: Liao
authors.forename: Lifang
authors.initials: L
authors.lastname: Yang
authors.forename: Wuzhong
authors.initials: W
authors.lastname: Jiang
authors.forename: Lunquan
authors.initials: L
authors.lastname: Sun
authors.forename: Ya
authors.initials: Y
authors.lastname: Cao
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D002199:Capillary Permeability; D002277:Carcinoma; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000098:blood supply* / Q000532:radiotherapy*; D009389:Neovascularization, Pathologic; D011379:Prognosis; D016896:Treatment Outcome