title: Multi-slice computed tomography: A tool for non-invasive temperature measurement?
abstract: OBJECTIVE
  To investigate the potential of multi-slice computed tomography (MSCT) as a tool for non-invasive temperature measurement.
  
  
  METHODS
  Samples of water, 0.9% saline, sunflower oil and dilutions of (1:32, 1:64, 1:128) contrast agent (Iopromid 370, BayerSchering Pharma, Berlin) were heated in a plexiglass phantom. In a first set-up, samples of 0.9% saline solution were scanned at defined temperatures (25 degrees -75 degrees C; 5 degrees C intervals) using a clinical CT scanner. Scan parameters (tube current-time product, tube voltage, collimation, slice thickness) were systematically varied. In a second set-up samples of the different fluids (water, sunflower oil, contrast agent dilutions) were scanned using the following scan protocol: 250 mAs, 140 kV, 1.2 mm collimation, 9.6 mm slice thickness. CT numbers were measured in reconstructed axial images at the different temperatures. A regression analysis was performed to investigate the relationship between temperature and CT number.
  
  
  RESULTS
  Standard deviation of measured CT numbers decreased with increasing tube current-time product, increasing tube voltage, thicker collimation and higher slice thickness. Regression analysis showed an inverse relationship between temperature and CT number for all fluids with regression coefficients of -0.471 (0.9% saline), 0.447 (water), -0.679 (sunflower oil), -0.420 (contrast agent 1:32), -0.414 (contrast agent 1:64) and -0.441 (contrast agent 1:128), respectively.
  
  
  CONCLUSIONS
  Multi-slice computed tomography can depict thermal density expansion of different fluids. Based on these results the implementation of a temperature discrimination of several degrees C at a high spatial resolution is achievable.
authors.affiliation: Department of Applied Medical Engineering, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, D-52074 Aachen, Germany. bruners@rad.rwth-aachen.de
authors.forename: Philipp
authors.initials: P
authors.lastname: Bruners
authors.forename: Elena
authors.initials: E
authors.lastname: Levit
authors.forename: Tobias
authors.initials: T
authors.lastname: Penzkofer
authors.forename: Peter
authors.initials: P
authors.lastname: Isfort
authors.forename: Christina
authors.initials: C
authors.lastname: Ocklenburg
authors.forename: Bernhardt
authors.initials: B
authors.lastname: Schmidt
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitz-Rode
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
mesh_terms: D055011:Ablation Techniques / Q000379:methods; D000704:Analysis of Variance; D001831:Body Temperature / Q000528:radiation effects; D006979:Hyperthermia, Induced / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008991:Monitoring, Physiologic / Q000379:methods; D019047:Phantoms, Imaging; D010938:Plant Oils / Q000737:chemistry; D012044:Regression Analysis; D012965:Sodium Chloride / Q000737:chemistry; D000074242:Sunflower Oil; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D010938:Plant Oils; D000074242:Sunflower Oil; D012965:Sodium Chloride