title: Diffusion-weighted and T2-weighted MR imaging for colorectal liver metastases detection in a rat model at 7 T: a comparative study using histological examination as reference.
abstract: OBJECTIVE
  To compare diffusion-weighted (DW) and T2-weighted MR imaging in detecting colorectal liver metastases in a rat model, using histological examination as a reference method.
  
  
  METHODS
  Eighteen rats had four liver injections of colon cancer cells. MR examinations at 7 T included FSE-T2-weighted imaging and SE-DW MR imaging (b = 0, 20 and 150 s/mm(2)) and were analysed by two independent readers. Histological examination was performed on 0.4-mm slices. McNemar's test was used to compare the sensitivities and the Wilcoxon matched pairs test to compare the average number of false-positives per rat.
  
  
  RESULTS
  One hundred and sixty-six liver metastases were identified on histological examination. The sensitivity in detecting liver metastases was significantly higher on DW MR than on T2-weighted images (99/166 (60 %) (reader 1) and 92/166 (55 %) (reader 2) versus 77/166 (46 %), P ≤ 0.001), without an increase in false-positives per rat (P = 0.773/P = 0.850). After stratification according to metastasis diameter, DW MR imaging had a significantly higher sensitivity than T2-weighted imaging only for metastases with a diameter (0.6-1.2 mm) similar to that of the spatial resolution of MR imaging in the current study.
  
  
  CONCLUSIONS
  This MR study with histological correlations shows the higher sensitivity of DW relative to T2-weighted imaging at 7 T for detecting liver metastases, especially small ones.
  
  
  CONCLUSIONS
  • Diffusion weighted (DW) sequences are increasingly used in magnetic resonance imaging (MRI). • DW has higher sensitivity for liver metastases than T2-weighted imaging at 7 T. • This increase in sensitivity is especially marked for small liver metastasis detection. • This higher sensitivity is confirmed in an animal model with histological correlation. • DW imaging has the potential for earlier diagnosis of small liver metastases.
authors: Laboratory of Physiological and Molecular Imaging of the Abdomen (IPMA) and Department of Radiology, University Paris Diderot, Sorbonne Paris Cité, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique- Hôpitaux de Paris, 100 Boulevard du Général Leclerc, 92118, Clichy Cedex, France. wagner.mathilde@gmail.com
authors: Mathilde
authors: M
authors: Wagner
authors: Léon
authors: L
authors: Maggiori
authors: Maxime
authors: M
authors: Ronot
authors: Valérie
authors: V
authors: Paradis
authors: Valérie
authors: V
authors: Vilgrain
authors: Yves
authors: Y
authors: Panis
authors: Bernard E
authors: BE
authors: Van Beers
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000473:pathology*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005189:False Positive Reactions; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000556:secondary*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D051381:Rats; D012680:Sensitivity and Specificity