title: Quantifying the effect of IV contrast media on integrated PET/CT: clinical evaluation.
abstract: OBJECTIVE
  The use of IV contrast media in PET/CT can result in an overestimation of PET attenuation factors that potentially can affect interpretation. The objective of this study was to quantify the effect of IV contrast media in PET/CT and assess its impact on patients with intrathoracic malignancies.
  
  
  METHODS
  Nine patients had CTs performed with and without IV contrast media followed by (18)F-FDG PET. PET images were reconstructed using contrast-enhanced and unenhanced CT. To quantify the effect of contrast media on standardized uptake values (SUV), similar regions of interest (ROIs) were drawn on the subclavian vein, heart, liver, spleen, and site of malignancy on both CT and corresponding reconstructed PET images, and the mean and maximum values were compared. In addition, two physicians blinded to the imaging parameters that were used evaluated the reconstructed PET images to assess whether IV contrast media had an effect on clinical interpretation.
  
  
  RESULTS
  For all patient studies, the subclavian vein region on the ipsilateral side of contrast media administration had the highest increase in CT numbers with a corresponding average SUV(max) increase of 27.1%. Similarly, ROIs of the heart and at the site of malignancy showed an increase in the maximum attenuation value with a corresponding average SUV(max) increase of 16.7% and 8.4%, respectively. Other locations had relatively small attenuation value differences with a correspondingly negligible SUV variation.
  
  
  CONCLUSIONS
  Although there is a significant increase in SUV in regions of high-contrast concentration when contrast-enhanced CT is used for attenuation correction, this increase is clinically insignificant. Accordingly, in PET/CT, IV contrast-enhanced CT can be used in combination with the PET to evaluate patients with cancer.
authors.affiliation: Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Box 56, Houston, TX 77030, USA. Omawlawi@mdanderson.org
authors.forename: Osama
authors.initials: O
authors.lastname: Mawlawi
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Erasmus
authors.forename: Reginald F
authors.initials: RF
authors.lastname: Munden
authors.forename: Tinsu
authors.initials: T
authors.lastname: Pan
authors.forename: Amy E
authors.initials: AE
authors.lastname: Knight
authors.forename: Homer A
authors.initials: HA
authors.lastname: Macapinlac
authors.forename: Donald A
authors.initials: DA
authors.lastname: Podoloff
authors.forename: Marvin
authors.initials: M
authors.lastname: Chasen
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D007275:Injections, Intravenous; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013350:Subclavian Vein; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed; D014283:Triiodobenzoic Acids / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D014283:Triiodobenzoic Acids; D019788:Fluorodeoxyglucose F18; C054871:ioversol