title: Experimental venous thrombi: MRI characteristics with histopathological correlation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the MRI characteristics of venous thrombus over set time thresholds with histopathological correlation in a porcine model.
  
  
  METHODS
  Inferior vena cava thrombi were induced in 12 pigs. MRI was performed in three pigs 2 h, 1 day, 3 days and 2 weeks after thrombus induction.
  
  
  RESULTS
  The MRI characteristics were analysed in correlation with histopathological findings. The thrombi after 2 hours, which consisted of red blood cells (RBCs), showed isointensity on T(1 )weighted images (T(1)WIs) and hyperintensity on both T(2 )weighted images (T(2)WIs) and diffusion-weighted images (DWIs). The mean apparent diffusion coefficient (ADC) value was 1.93 × 10(-3) mm(2) s(-1). The thrombi after Day 1, which consisted of RBCs and migrating neutrophils at the periphery, showed isointensity on T(1)WIs, slight hyperintensity on T(2)WIs and hypointensity on DWIs. The mean ADC value was 1.62 × 10(-3) mm(2) s(-1) [corrected]. The thrombi after Day 3, which consisted of RBCs and peripheral inflammatory cells including macrophages, showed isointensity with peripheral hyperintense regions on T(1)WIs and hypointensity on both T(2)WIs and DWIs. The mean ADC value was 1.67 × 10(-3) mm(2) s(-1). After 2 weeks, the thrombi, which revealed RBC lysis surrounded by granulation tissues, showed isointensity on T(1)WIs and hyperintensity on T(2)WIs and DWIs. The mean ADC value was 2.48 × 10(-3) mm(2) s(-1).
  
  
  CONCLUSIONS
  The temporal MRI characteristics seemed to be related to chemical and physical changes in RBC and organisation of granulation tissues. Free radicals generated by macrophages might also be related to some extent.
authors.affiliation: Department of Radiology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan. s500820@nifty.com
authors.forename: M
authors.initials: M
authors.lastname: Ichiki
authors.forename: Y
authors.initials: Y
authors.lastname: Sakai
authors.forename: M
authors.initials: M
authors.lastname: Nango
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Matsui
authors.forename: H
authors.initials: H
authors.lastname: Cho
authors.forename: T
authors.initials: T
authors.lastname: Kitayama
authors.forename: T
authors.initials: T
authors.lastname: Sahara
authors.forename: N
authors.initials: N
authors.lastname: Otani
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
authors.forename: Y
authors.initials: Y
authors.lastname: Miki
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging; D004912:Erythrocytes / Q000473:pathology; D005260:Female; D006097:Granulation Tissue / Q000473:pathology; D008279:Magnetic Resonance Imaging; D013552:Swine; D013997:Time Factors; D014682:Vena Cava, Inferior / Q000473:pathology; D020246:Venous Thrombosis / Q000473:pathology*