Biased visualization of hypoperfused tissue by computed tomography due to short imaging duration: improved classification by image down-sampling and vascular models

Irene Klærke Mikkelsen, P. Simon Jones, Lars Riisgaard Ribe, Josef Alawneh, Josep Puig, Susanne Lise Bekke, Anna Tietze, Jonathan H. Gillard, Elisabeth A. Warburton, Salva Pedraza, Jean-Claude Baron, Leif Østergaard, Kim Mouridsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Objectives Lesion detection in acute stroke by computedtomography perfusion (CTP) can be affected by incomplete bolus coverage in veins and hypoperfused tissue, so-called bolus truncation (BT), and low contrast-to-noise ratio (CNR).We examined the BT-frequency and hypothesized that image down-sampling and a vascular model (VM) for perfusion calculation would improve normo- and hypoperfused tissue classification.
Methods CTP datasets from 40 acute stroke patients were retrospectively analysed for BT. In 16 patients with hypoperfused tissue but no BT, repeated 2-by-2 image down-sampling and uniform filtering was performed, comparing CNR to perfusion-MRI levels and tissue classification to that of unprocessed data. By simulating reduced scan duration, the minimum scanduration at which estimated lesion volumes came within 10 % of their true volume was compared for VM and state-of-the-art algorithms.
Results BT in veins and hypoperfused tissue was observed in 9/40 (22.5 %) and 17/40 patients (42.5 %), respectively. Down-sampling to 128×128 resolution yielded CNR comparable to MR data and improved tissue classification (p=0.0069). VM reduced minimum scan duration, providing reliable maps of cerebral blood flow and mean transit time: 5 s (p=0.03) and 7 s (p<0.0001), respectively).
Conclusions BT is not uncommon in stroke CTP with 40-s scan duration. Applying image down-sampling and VM improve tissue classification.
Original languageEnglish
JournalEuropean Radiology
ISSN0938-7994
DOIs
Publication statusE-pub ahead of print - 2015
Externally publishedYes

Keywords

  • CTP
  • Bolus truncation
  • Deconvolution
  • Acute stroke
  • Noise reduction

Cite this

Klærke Mikkelsen, I., Jones, P. S., Riisgaard Ribe, L., Alawneh, J., Puig, J., Bekke, S. L., Tietze, A., Gillard, J. H., Warburton, E. A., Pedraza, S., Baron, J-C., Østergaard, L., & Mouridsen, K. (2015). Biased visualization of hypoperfused tissue by computed tomography due to short imaging duration: improved classification by image down-sampling and vascular models. European Radiology. https://doi.org/10.1007/s00330-015-3602-x