title: Quantitative assessment of effects of motion compensation for liver and lung tumors in CT perfusion.
abstract: OBJECTIVE
  To study the effects of four different rigid alignment approaches on both time-concentration curves (TCCs) and perfusion maps in computed tomography perfusion (CTp) studies of liver and lung tumors.
  
  
  METHODS
  Eleven data sets in patients who were subjected to axial CTp after contrast agent administration were assessed. Each data set consists of four different sequences, according to the different rigid alignment configurations considered to compute blood flow perfusion maps: no alignment, translational, craniocaudal, and three dimensional (3D). The color maps were built on TCCs according to the maximum slope method. The effects of motion correction procedures on the reliability of TCCs and perfusion maps were assessed both quantitatively and visually.
  
  
  RESULTS
  TCCs built after 3D alignments show the best indices as well as producing the most reliable maps. We show examinations in which the translational alignment only yields more accurate TCCs, but less reliable perfusion maps, than those achieved with no alignment. Furthermore, we show color maps with two different perfusion patterns, both considered reliable by radiologists, achieved with different motion correction approaches.
  
  
  CONCLUSIONS
  The quantitative index we conceived allows relating quality of 3D alignment and reliability of perfusion maps. A better alignment does not necessarily yield more reliable perfusion values: color maps resulting from either alignment procedure must be critically assessed by radiologists. This achievement will hopefully represent a step forward for the clinical use of CTp studies for staging, prognosis, and monitoring values of therapeutic regimens.
authors.affiliation: Department of Computer Science and Engineering (DISI), University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy; Advanced Research Center on Electronic Systems for Information and Communication Technologies "Ercole De Castro" (ARCES), University of Bologna, Via Toffano 2/2, 40125, Bologna, Italy. Electronic address: alessandro.bevilacqua@unibo.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bevilacqua
authors.affiliation: Radiology Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 47014, Meldola (FC), Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Barone
authors.affiliation: Advanced Research Center on Electronic Systems for Information and Communication Technologies "Ercole De Castro" (ARCES), University of Bologna, Via Toffano 2/2, 40125, Bologna, Italy; Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi" (DEI), University of Bologna, Viale Risorgimento 2, 40136, Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Malavasi
authors.affiliation: Radiology Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 47014, Meldola (FC), Italy.
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Gavelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009038:Motion; D009068:Movement; D009389:Neovascularization, Pathologic / Q000150:complications / Q000000981:diagnostic imaging*; D055420:Perfusion Imaging / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: TCC; image processing; liver; lung; motion compensation; perfusion imaging