title: Diffusion-weighted MRI findings of treated and untreated retroperitoneal fibrosis.
abstract: OBJECTIVE
  We aimed to evaluate diffusion-weighted imaging (DWI) findings in patients with treated and untreated retroperitoneal fibrosis (RPF).
  
  
  METHODS
  We analyzed magnetic resonance imaging examinations of 44 RPF patients (36 male, 8 female), of which 15 were untreated and 29 were under therapy. Qualitative DWI and T1 postcontrast signal intensities and the largest perivascular extent of RPF were compared between treated and untreated groups and correlated to erythrocyte sedimentation rate and C-reactive protein values. Quantitative DWI signal intensities and apparent-diffusion-coefficients were calculated in regions-of-interest, together with a relative index between signal intensities of RPF and psoas muscle in 15 untreated patients and 14 patients under treatment with remaining perivascular fibrosis of more than 5 mm.
  
  
  RESULTS
  The extent of RPF in untreated patients was significantly larger compared with the extent of RPF in treated patients (P <0.0001). DWI signal intensities were significantly higher in untreated patients than in patients under therapy (mean, 27 s/mm2 vs. 20 s/mm2; P = 0.009). The calculated DWI-index was significantly higher in untreated patients than in patients under therapy (P = 0.003).
  
  
  CONCLUSIONS
  Our data show significant differences in the DWI findings (b800 signal intensities and relative DWI-index) of patients with treated and untreated RPF. DWI is a promising technique in the assessment of disease activity and the selection of patients suitable for medical therapy.
authors.affiliation: Department of Diagnostic and Interventional Radiology, HELIOS Medical Center Wuppertal, University Hospital Witten/Herdecke, Wuppertal, Germany; Center for Clinical Medicine Witten/Herdecke University Faculty of Health, Wuppertal, Germany. lars.kamper@helios-kliniken.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Kamper
authors.forename: Alexander Sascha
authors.initials: AS
authors.lastname: Brandt
authors.forename: Hendrik
authors.initials: H
authors.lastname: Ekamp
authors.forename: Nadine
authors.initials: N
authors.lastname: Abanador-Kamper
authors.forename: Werner
authors.initials: W
authors.lastname: Piroth
authors.forename: Stephan
authors.initials: S
authors.lastname: Roth
authors.forename: Patrick
authors.initials: P
authors.lastname: Haage
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D012185:Retroperitoneal Fibrosis / Q000097:blood / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D012189:Retrospective Studies
chemical_list: D002097:C-Reactive Protein