title: Quantitative tissue perfusion measurements in head and neck carcinoma patients before and during radiation therapy with a non-invasive MR imaging spin-labeling technique.
abstract: OBJECTIVE
  Tumor blood flow, tumor tissue perfusion and oxygen supply have substantial influence on the responsiveness of tumors to radiotherapy. This study was aimed at implementing and evaluating a non-invasive functional magnetic resonance (MR) imaging spin-labeling technique at a main magnetic field strength of 2T for measuring tissue perfusion changes in head and neck carcinoma patients before and during radiotherapy.
  
  
  METHODS
  Tissue perfusion was determined quantitatively in ten patients with head and neck cancer. Five patients were investigated twice during radiation therapy. For perfusion measurements, a non-invasive MR spin-labeling technique was employed: The longitudinal relaxation time T(1) was measured with segmented Snapshot-FLASH imaging after either slice-selective or non-selective spin inversion. Perfusion values were calculated pixelwise employing a two-compartment tissue model. With this technique no contrast agents are required so that repetitive measurements are possible. Perfusion images with a slice thickness of 10mm and an in-plane resolution of 1.9x2.8mm(2) were acquired at a total scan time of 8:30min per scan.
  
  
  RESULTS
  With the non-invasive MR imaging technique it was possible to visualize tumor and normal tissue perfusion as well as perfusion changes in the course of radiotherapy with a spatial resolution of less than 3mm. Among the investigated subjects measured tumor perfusion and changes in perfusion were heterogenous. In 4/5 patients studied at the start and end of radiotherapy, perfusion decreased, while in one patient there was an increase.
  
  
  CONCLUSIONS
  A method is presented that allows non-invasive and repetitive characterization of tissue perfusion. This parameter may be used for treatment stratification, especially in treatments that use vasomodulation or anti-angiogenic agents.
authors.affiliation: Experimentelle Physik 5, Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany
authors.forename: Peter
authors.initials: P
authors.lastname: Schmitt
authors.forename: Markus
authors.initials: M
authors.lastname: Kotas
authors.forename: Anja
authors.initials: A
authors.lastname: Tobermann
authors.forename: Axel
authors.initials: A
authors.lastname: Haase
authors.forename: Michael
authors.initials: M
authors.lastname: Flentje
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity; D002277:Carcinoma / Q000098:blood supply* / Q000532:radiotherapy; D003196:Computer Graphics; D006258:Head and Neck Neoplasms / Q000098:blood supply* / Q000532:radiotherapy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*