Original ArticlesFibrosis and Pancreatic Lesions Counterintuitive Behavior of the Diffusion Imaging–Derived Structural Diffusion Coefficient DKlau, Miriam MD*β; Gaida, Matthias M. MD†; Lemke, Andreas MSc‡; Grünberg, Katharina MD§; Simon, Dirk MSc∥; Wente, Moritz N. MD¶; Delorme, Stefan MD§; Kauczor, Hans-Ulrich MD*; Grenacher, Lars MD*; Stieltjes, Bram MD, PhD#Author Information From the Departments of *Diagnostic and Interventional Radiology, †Department of Pathology, and ‡Computer Assisted Clinical Medicine, Faculty of Medicine Mannheim, University of Heidelberg; Departments of §Radiology, and ∥Medical Physics in Radiology, German Cancer Research Center (DKFZ); ¶Department of Surgery, University of Heidelberg; and #Department of Radiology, Section Quantitative Imaging Based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany. Received for publication September 1, 2011; and accepted for publication, after revision, October 4, 2012. Conflicts of interest and sources of funding: Supported by the German Research Foundation (DFG) grant SFB Cognition-Guided Surgery (M.K. and B.S.). The authors report no conflicts of interest. Reprints: Bram Stieltjes, MD, PhD, Department of Radiology, Section Quantitative Imaging Based Disease Characterization, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 290, 69120 Heidelberg, Germany. E-mail: [email protected]. Investigative Radiology: March 2013 - Volume 48 - Issue 3 - p 129-133 doi: 10.1097/RLI.0b013e31827ac0f1 Buy Metrics Abstract Introduction Stroma reaction leading to fibrosis is the most characteristic histopathological feature of both pancreatic carcinoma and chronic pancreatitis with increased fibrosis compared with healthy pancreatic tissue and further increased fibrosis during radiochemotherapy. Recent studies using intravoxel incoherent motion–derived parameters did not show differences for structural diffusion constant D between these 2 diseases. The aim of this study was to verify the hypothesis that D correlates with the histopathological grade of fibrosis in pancreatic lesions. Materials and Methods We included 15 patients with histopathologically proven pancreatic carcinoma and 9 patients with histopathologically proven focal chronic pancreatitis. Diffusion-weighted magnetic resonance imaging was performed using 10 b values between 25 and 800 s/mm2 before surgery. We calculated the apparent diffusion coefficient and the intravoxel incoherent motion–derived parameters D and f within tumors and focal chronic pancreatitis. The resected tissue was evaluated with regard to the grade of fibrosis. Results Fourteen patients were found to have moderate fibrosis and 10 patients had severe fibrosis. The difference between the D values for the moderate and severe fibrosis was significant with mean (SD) D value of 1.02 × 10−3 (0.48 × 10−3 mm2/s) and mean (SD) D of 1.22 × 10−3 (0.76 × 10−3) mm2/s. There were no significant differences for the f and ADC values. Conclusions Contrary to our hypothesis, D rises from moderate to severe fibrosis. It seems that cellular complexes surrounded by fibrosis provide more structural limitations than does fibrosis alone. Our data suggest that D is not intuitively related to the degree of fibrosis. Compared with healthy tissue, D is reduced in moderate fibrosis but increases when severe fibrosis is present. © 2013 Lippincott Williams & Wilkins, Inc.