title: The Therapeutic Response of Gastrointestinal Stromal Tumors to Imatinib Treatment Assessed by Intravoxel Incoherent Motion Diffusion-Weighted Magnetic Resonance Imaging with Histopathological Correlation.
abstract: OBJECTIVE
  To exploit the intravoxel incoherent motion (IVIM) diffusion-weighted (DW) MRI when evaluating the therapeutic response of gastrointestinal stromal tumors (GIST) to Imatinib in a mouse model.
  
  
  METHODS
  Mice with xenografts bearing cells from the GIST-T1 cell line were randomly divided into a treated group receiving Imatinib and a control group. DWMRI scans with 14 b-values (0-1500 s/mm2) were performed before and after treatment (days 1, 3 and 7). IVIM related parameters perfusion fractions (fp) and perfusion-related diffusion coefficients (D*) and the conventional apparent diffusion coefficients (ADC) were calculated by fitting the DWMRI signal decay. The mean changes from baseline to each post-treatment time point for each measurement (ΔADC, Δfp and ΔD*) were calculated. The differences of mean changes between the two groups were tested for statistical significance. Histopathological analyses including Ki-67, CD31, TUNEL and H&E were conducted in conjunction with the MRI scans.
  
  
  RESULTS
  Increases in ADC of the treated group were higher than those of the control group after treatment, whereas statistical significances were not observed. Compared to the control group, D* in the treated group decreased significantly (ΔD*treated = -41%, -49%, and -49% with P = 0.0001, 0.0001 and 0.0001), and fp increased significantly (Δfptreated = 79%, 82% and 110%, with P = 0.001, 0.0001 and P = 0.0007) on days 1, 3 and 7 after treatment. Histopathological analyses demonstrated different tumor tissue characteristics between the treated and control groups.
  
  
  CONCLUSIONS
  IVIM measurements may serve as more sensitive imaging biomarkers than ADC when assessing GIST response to Imatinib as early as one day after treatment.
authors.affiliation: Department of Radiology, People's Hospital, Peking University, Beijing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Pan
authors.affiliation: Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital of Chicago, Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America.
authors.forename: Jie
authors.initials: J
authors.lastname: Den
authors.affiliation: People's Hospital, Peking University, Clinical Epidemiology and Medical Statistics, Beijing, China.
authors.forename: Chunfang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: GE Healthcare, Shanghai, China.
authors.forename: He
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Radiology, People's Hospital, Peking University, Beijing, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Radiology, People's Hospital, Peking University, Beijing, China.
authors.forename: Weizhen
authors.initials: W
authors.lastname: Wu
authors.affiliation: Department of Radiology, People's Hospital, Peking University, Beijing, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Hong
authors.affiliation: Department of Radiology, People's Hospital, Peking University, Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D006801:Humans; D000068877:Imatinib Mesylate / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D023041:Xenograft Model Antitumor Assays
chemical_list: D000068877:Imatinib Mesylate