title: Potential of gadolinium as contrast material in second generation dual energy computed tomography - An ex vivo phantom study.
abstract: OBJECTIVE
  To evaluate the potential of gadolinium (Gd) as contrast material (CM) in second generation dual energy computed tomography (DECT).
  
  
  METHODS
  In a phantom model, DECT post-processing was used to increase Gd attenuation using advanced monoenergetic extrapolation (MEI), to create virtual non-contrast images (Gd-VNC) and Gd maps and to quantify Gd content. Dilutions of Gd and iodinated CM (7-296 HU) were filled in syringes, placed in an attenuation phantom and scanned with standard DECT protocols (80 &100/Sn140 kV). MEI (40-190 keV) and VNC images as well as Gd maps were computed. The amount of Gd was quantified and the accuracy was compared to iodine images. Linear regression models were calculated to evaluate Gd attenuation of equivolume CM doses and clinical MRI doses.
  
  
  RESULTS
  Applying monoenergetic reconstructions and using Gd as contrast agent (Gd MEI 40 keV) doubled Hounsfield-Units (HU) and 90% of the SNR (averaged: 225 HU, SNR3.1) are achievable, as compared to iodinated CM at 120 kV (averaged:110 HU, SNR3.5), at Gd doses of 1.0mmol/kg BW. The accuracies of Gd-VNC (deviation, 6±12 HU) images and Gd quantification (measurement error, 17%) were not significantly different to those of iodine enhanced images (VNC:deviation, 2±11 HU; measurement error,14%).
  
  
  CONCLUSIONS
  Using monoenergetic extrapolation at 40keV, it is possible to increase Gd-CM attenuation significantly. Thus, equivalent HU and half the SNR in comparison to a standard dose of ICM at 120kV can be expected at a Gd-CM dose of 0.5mmol/kg BW. Post-processing features of iodine based DECT like monoenergetic or VNC images, iodine maps or quantification of CM are feasible with the use of Gd-CM.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany. Electronic address: malte.bongers@med.uni-tuebingen.de.
authors.forename: Malte N
authors.initials: MN
authors.lastname: Bongers
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schabel
authors.affiliation: Siemens Healthcare GmbH, Siemensstraße 1, 91301 Forchheim, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany.
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstrasse 5, 40225 Düsseldorf, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
mesh_terms: D003287:Contrast Media; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007455:Iodine; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007455:Iodine; D005682:Gadolinium
keywords: Contrast material; Dual energy computed tomography; Gadolinium; Gadolinium mapping; Monoenergetic extrapolation; Virtual non-contrast images