title: Acute tumor vascular effects following fractionated radiotherapy in human lung cancer: In vivo whole tumor assessment using volumetric perfusion computed tomography.
abstract: OBJECTIVE
  To quantitatively assess the in vivo acute vascular effects of fractionated radiotherapy for human non-small-cell lung cancer using volumetric perfusion computed tomography (CT).
  
  
  METHODS
  Sixteen patients with advanced non-small-cell lung cancer, undergoing palliative radiotherapy delivering 27 Gy in 6 fractions over 3 weeks, were scanned before treatment, and after the second (9 Gy), fourth (18 Gy), and sixth (27 Gy) radiation fraction. Using 16-detector CT, multiple sequential volumetric acquisitions were acquired after intravenous contrast agent injection. Measurements of vascular blood volume and permeability for the whole tumor volume were obtained. Vascular changes at the tumor periphery and center were also measured.
  
  
  RESULTS
  At baseline, lung tumor vascularity was spatially heterogeneous with the tumor rim showing a higher vascular blood volume and permeability than the center. After the second, fourth, and sixth fractions of radiotherapy, vascular blood volume increased by 31.6% (paired t test, p = 0.10), 49.3% (p = 0.034), and 44.6% (p = 0.0012) respectively at the tumor rim, and 16.4% (p = 0.29), 19.9% (p = 0.029), and 4.0% (p = 0.0050) respectively at the center of the tumor. After the second, fourth, and sixth fractions of radiotherapy, vessel permeability increased by 18.4% (p = 0.022), 44.8% (p = 0.0048), and 20.5% (p = 0.25) at the tumor rim. The increase in permeability at the tumor center was not significant after radiotherapy.
  
  
  CONCLUSIONS
  Fractionated radiotherapy increases tumor vascular blood volume and permeability in human non-small-cell lung cancer. We have established the spatial distribution of vascular changes after radiotherapy; greater vascular changes were demonstrated at the tumor rim compared with the center.
authors.affiliation: Marie Curie Research Wing, Mount Vernon Hospital, Northwood, United Kingdom.
authors.forename: Quan-Sing
authors.initials: QS
authors.lastname: Ng
authors.forename: Vicky
authors.initials: V
authors.lastname: Goh
authors.forename: Jessica
authors.initials: J
authors.lastname: Milner
authors.forename: Anwar R
authors.initials: AR
authors.lastname: Padhani
authors.forename: Michele I
authors.initials: MI
authors.lastname: Saunders
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hoskin
mesh_terms: D001810:Blood Volume / Q000502:physiology / Q000528:radiation effects*; D002199:Capillary Permeability / Q000502:physiology / Q000528:radiation effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D010166:Palliative Care; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods