Yeonjeong Park, Presenter: Nothing to Disclose

Jeong-Min Lee MD, Abstract Co-Author: Advisory Board, Bayer AG

Byung I. Choi MD, PhD, Abstract Co-Author: Research collaboration, Taewoong Medical Co, Ltd Research Consultant, Medison Co, Ltd

Han Kwang Yang MD, Abstract Co-Author: Nothing to Disclose

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) to differentiate gastric cancer from healthy gastric wall using the apparent diffusion coefficient (ADC) and parameters derived from the intravoxel incoherent motion (IVIM) theory

26 patients with pathologically confirmed gastric cancer (median 61 years; 16 male, 10 female) were enrolled in this study: there were 21 patients with advanced gastric cancer and five with early gastric cancer. Unenhanced T1WI, T2WI, dynamic imaging and DW-MRI were preoperatively performed in each patient on a 3T whole body scanner (Siemens Trio) with eight different b values ranging from 0 to 1000 s/mm2. From each DW image, four IVIM parametric maps were derived; ADC, pure molecular diffusion (Dslow), perfusion-related diffusion (Dfast), and perfusion fraction (PF). On each map, three regions of interest (ROIs) were selected within the extent of cancer and another three in normal gastric wall. The mean value of each parameter within the three ROIs in a tumor was compared with that in healthy wall by paired t-test.

All advanced gastric cancers showed higher signal intensity than that of normal gastric wall on high b-factor DWI (> b=500) and showed restricted diffusion on ADC map. Therefore, DWI provided better conspicuity (69% with excellent conspicuity) than T2WI (50%) for advanced gastric cancer. However, DW-MRI could detect only 2 out of the 5 cases with early gastric cancer (pT1b). The tumor detection rate of DWI was 85% (22 of 26) which was similar to 88% (23 of 26) for combined image set of T1- and T2-WI and dynamic imaging. In addition, DWI depicted peritoneal seeding lesions in two of the three patients with dry pertioneal seeding which were not well demonstrated on conventional MRI. All of the four IVIM parameters of gastric cancer lesions were significantly lower than those of normal gastric wall (p < 001).

DWI with multiple b-values can effectively demonstrate advanced gastric cancers with excellent lesion conspicuity, and may have a potential role for detecting peritoneal seeding. The high level of conspicuity stems from the reduction in both diffusion and perfusion, reflected in the significant decrease of the IVIM coefficients within gastric carcinomas.

DW-MRI, consolidated by the IVIM concept, is a highly useful modality for detecting advanced gastric cancer, with an excellent level of conspicuity.

Park, Y, Lee, J, Choi, B, Yang, H, Intravoxel Incoherent Motion (IVIM) Diffusion-weighted MR Imaging (DW-MRI) in the Preoperative Evaluation of Gastric Cancer: Comparison of Apparent Diffusion Coefficient and IVIM Derived Parameters.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034571.html